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BEFORE THE
FEDERAL ENERGY REGULATORY COMMISSION
APPLICATION FOR LICENSE FOR MAJOR PROJECT
SUSITNA . HYDROELECTRIC PROJECT
VOLUME 6A
EXHIBIT E
Chapter 3
FEBRUARY 1983
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.___ __ ALASKA POWER AUTHORITY __ __.
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SUSITNA HYDROELECTRIC PROJECT
VOLUME 6A
EXHIBIT E CHAPTER 3
FISH, WILDLIFE AND BOTANICAL RESOURCES
TABLE OF CONTENTS
1 -INTRODUCTION ............................................. E-3-1
1.1 -Baseline Description ............................... E-3-1
1.2-Impact Assessments ................................. E-3-1
1.3 -Mitigation Plans ................................... E-3-3
2-FISH RESOURCES OF THE SUSITNA RIVER DRAINAGE ............. E-3-7
2.1 -Overview of the Resources . . . . . . . . . . . • . . . . . . . . . . . . . . E-3-7
2.1.1 -Description of the Study Area for
Fish Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-3-7
2.1.2-Data Collection and Analysis Methods ........ E-3-7
2.1.3-Threatened and Endangered Species .......... E-3-11
2.1.4-Overview of Important Species .............. E-3-11
2.1.5 -Contribution of Commercial and
Non-Commercial Fishery ..................... E-3-11
2.2 -Species Biology and Habitat Utilization in the
Susitna Drainage ................................... E-3-15
2.2.1-Species Biology ............................ E-3-15
2.2.2-Habitat Utilization ........................ E-3-46
2.2.3-Streams of Access Road Corridor ............ E-3-68
2.2.4-Streams of the Transmission ................ E-3-70
2.3-Anticipated Impacts to Aquatic Habitat ............. E-3-71
2.301 -Anticipated Impacts to Aquatic Habitat
Associated with Watana Dam ... 0 ............. E-3-72
2.3.2 -Anticipated Impacts to Aquatic Habitat
Associated with Devil Canyon ............... E-3-124
2.3.3 -Impacts Associated with Access Roads,
Site Roads and Rai lrods .................... E-3-124
2.3.4-Impacts Associated with Access Roads,
Site Roads and Railroads ...... 0 ............ E-3-124
2.4-Mitigation Issues and Mitigation Measures ····o····· E-3-141
2.4.1 -Approach to Mitigation ........... •o ••••••••• E-3-141
2.4.2-Selection of Project Evaluation Species .... E-3-147
2.4.3-Mitigation of Construction Impacts Upon
Fish and Aquatic Habitats .................. E-3-150
2.4.4 -Mitigation of Filling and Operation
Impacts .... 0 ............................... E-3-160
2.4.5-Cumulative Effectiveness of Mitigation .... 0 E-3-175
TABLE OF CONTENTS
Page
2.5-Aquatic Studies Program ............................ E-3-179
2.5.1-Preconstruction Phase ...................... E-3-179
2.5.2-Construction Phase ......................... E-3-179
2.5.3-Filling and Operation Phase ................ E-3-180
2.6 -Monitoring Studies ................................. E-3-180
2.6.1-Construction Monitoring .................... E-3-180
2.6.2-Operational Monitoring ..................... E-3-182
2.7-Cost of Mitigation ................... : ............. E-3-185
2.8 -Agency Consultation on Fisheries Mitigation
Measures ........................................... E-3-186
2.8.1-U.S. Fish and Wildlife Service ............. E-3-189
2.8.2 -Alaska Department of Fish and Game ......... E-3-190
3-BOTANICAL RESOURCES ...................................... E-3-191
3.1 -Introduction ....................................... E-3-191
3.1.1-Regional Botanical Setting ................. E-3-192
3.1.2 -Floristics ................................. E-3-193
3.1.3 -Coostribution to Wildlife, Recreation,
Subs i stance, and Commerce .................. E-3-195
3.2 -Baseline Description ............................... E-3-196
3.2.1-Threatened or Endangered Plants ............ E-3-196
3.2.2-Plant Communities .......................... E-3-198
3.2.3 -Wetlands ................................... E-3-220
3. 3 -Impacts ............................................ E-3-224
3.3.1-Watana Development ......................... E-3-225
3.3.2-Devil Canyon Development ................... E-3-240
3.3.3 -Access ..................................... E-3-243
3.3.4-Transmission Corridors ..................... E-3-244
3.3.5 -Impacts to Wetlands ........................ E-3-245
3.3.6 ~Prioritization of Impact Issues ............ E-3-246
3.4 -Mitigation Plan .................................... E-3-250
3.4.1-Introduction ............................... E-3-250
3.4.2 -Option Analysis ............................ E-3-252
3.4.3-Mitigation Summary ......................... E-3-291
4 -WILDLIFE ................................................. E-3-294
4.1-Introduction ....................................... E-3-294
4.1.1 The Vertebrate Fauna ....................... E-3-294
4.1.2-Threatened or Endangered Species ........... E-3-295
4.1.3 -Species Contributing to Recreation,
Subsistence, and Commerce .................. E-3-295 p:----
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TABLE OF CONTENTS
4.2-Baseline ~escription .............................. .
4 • 2 • 1 -B' i g G arne .................................. .
4. 2. 2 -~urbearers ................................ .
4.2.3-Bitds ..................................... .
4.2.4-~on-Game (Small} Mammals .................. .
4.3 -Impacts ........................................... .
4.3.1-Watana Development ........................ .
4.3.2 -Devil Canyon Development .................. .
4.3.3-Access Roads and Railway .................. .
4.3.4 -Transmission Lines ........................ .
4.3.5 -Impact Summary ............................ .
/4.4 -Mitigation Plan ................................... .
{.// 4.4.1 -Impact Issues and Option Analysis ...... , .. .
REFERENCES
4.4.2 -Mitigation Plans and Monitoring
Investigations ...................•.........
4.4.3-Cost Analysis and Schedules ............... .
4.4.4 -Documentation of Agency Recommendations
E-3-296
E-3-296
E-3-354
E-3-366
E-3-388
E-3-396
E-3-396
E-3-462
E-3-476
E-3-492
E-3-499
E-3-508
E-3-508
E-3-523
E-3-544
E-3-546
-Introduction ............................................ E-3-551
-Fisheries ............................................... E-3-552
-Wildlife and Botanical Resources ........................ E-3-566
LIST OF TABLES
LIST OF FIGURES
Appendix E3A-Fish and Wildlife Mitigation Policy
Appendix E3B Environmental Guidelines Memorandum
Appendix E3C-Preliminary List of Plant Species Upper and
Middle Susitna River
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Appendix E3D-Preliminary list of Plant Species Intertie Area
Appendix E3E -Status, Habitat Use and Relative Abundance
of Bird Species in the Middle Susitna Basin
Appendix E3F-Status of Relative Abundance of Bird Species
in the Lower Susitna Basin
Appendix E3G -Scientific Names of Mammal Species
Appendix E3H-Methods Used to Determine ~bose Browse Utili-
zation and Carrying Capacity within the Middle
Sus itna Bas in
Appendix E31 -Explanation and Justification of Artifical
Nest Mitigation
Appendix E3J -Personal Communications
GLOSSARY
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LIST OF TABLES
E.3.1
E.3.2
E.3.3
E.3.4
E.3.5
E.3.6
E.3.7
E.3.8
E.3.9
E.3.10
E. 3.11
E.3.12
Mitigation Options Analysis Structure
Recommended by Susitna Hydroelectric Project,
Alaska Department of Fish and Game and
the U.S. Fish and Wildlife Service
Common and Scientific Names of Fish Species
Recorded from the Susitna Basin
Commercial Catch of Upper Cook Inlet
Salmon in Numbers of Fish by Species,
1954-1982
Commercial Catch of Lower Cook Inlet
Salmon in Number of Fish By Species,
1954-1982
Side-Scan Sonar Counts of Salmon Migrating
Past Yentna Station, and Peterson Population
Estimates and Corresponding 95% Confidence
Interv~ls of Salmon Migrating to Sunshine,
Talkeetna and Curry Stations, 1981-1982
Susitna Basin Sport Fish Harvest and Effort by
Fishery and Species -1978, 1979, 1980, 1981
Chinook Salmon Escapement Counts of Susitna
River Basin Streams from 1976 to 1982, Adult
Anadromous Investigations, Susitna Hydro
Studies, 1982
1982 Chinook Salmon Escapement Surveys of
Susitna River Basin Streams Adult Anadromous
Investigations, Susitna KYdro Studies, 1982
Preliminary Results of 1982 Smolt Trap
Catches at Talkeetna Station
Adult Salmon Migration Rates
(in miles per day)
Analysis of Sockeye Salmon Age Data by Percent
From Escapement Samples Collected at Susitna, . .
Yentna, Sunshine, Talkeetna and Curry Stations,
Adult Anadromous Investigations, Susitna Hydro
Studies, 1981
Estimated Number of Slough Spawning Sockeye,
Chum and Pink Salmon in Sloughs Between Devil
Canyon and Talkeetna, 1981 to 1982
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LIST OF TABLES
E.3.13 Mainstem Susitna River Salmon Spawning
Locations Identified in 1981-1982
E.3.14 Coho Salmon Juveniles, Percent Incident at
Habitat Location Sites on the Mainstem Susitna
River and Its Tributary Mouths Between Cook
Inlet and Devil Canyon-November 1980 to May 1981
E.3.15 Coho Salmon Juveniles, Percent Incident at
Habitat Location Sites on the Mainstem Susitna
River and Its Tributary Mouths Between Cook
Inlet and Talkeetna -June to September 1981
E.3.16 Arctic Grayling Hook and Line Total Catch
by Tributary Between the Mouth and Proposed
Impoundment Elevations (PIE) and Mouth in
the Impoundment Study Area -1981
E.3.17 Arctic Grayling Population Estimates for
the Reach of Major Tributaries in the Watana
and Devil Canyon Impoundment Areas
E.3.18 Peterson Population Estimate for Arctic Grayling
by Age Group in the Watana Impoundment.Area,
Summer 1982
E.3.19 Streams Crossed by Denali Highway
(Cantwell to Watana Access Junction)
E.3.20 Streams to be Crossed by Watana Access
Road (Denali Highway to Watana Dam)
E.3.21 Streams to be Crossed by Devil Canyon
Access Road and Transmission Line Between
Watana and Devil Canyon, and Railroad
Spur from Gold Creek to Devil Canyon
E.3.22 Waterbod1es to be Crossed by the Susitna
Transmission Line (Anchorage to Willow)
E.3.23 Waterbodies to be Crossed by the Susitna
Transmission Line (Healy to Fairbanks)
E. 3. 24 , Effects of Surfacing and Earthwork on
Physical and Chemical Characteristics of
Aquatic Habitat
E.3.25 Increase in Water Surface Elevation
During Initial Fill of Watana Reservoir
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LIST OF TABLES
E.3.26 Comparison of Average Monthly Streamflows
at Gold Creek During Initial Filling of
Watana Reservoir
E.3.27 Major Impact Issues During Filling of
Watana Reservo·ir Regarding Salmonids in
the Talkeetna-to-Devil Canyon Reach
E.3.28 Major Tributaries to be Inundated
E.3.29 Comparison of Average Monthly Streamflows
at Sunshine During Initial Filling of
Watana Reservoir
E.3.30 Comparison of Average Monthly Streamflows
at Susitna Station During Initial Filling
of Watana Reservoir
E.3.31 Major Impact Issues During Operation of
Watana Reservoir Regarding Salmonids in
the Ta 1 keetna-to-Dev·i 1 Canyon Reach
E.3.32 Comparison of Average Monthly Streamflows
at Gold Creek Station Under Operation of
Watana Dam
E.3.33 Comparison of Average Monthly Streamflows
at Sunshine Station Under Operation of
Watana Dam
E.3.34 Comparison of Average Monthly Streamflows
at Susitna Station Under Operation of
Watana Dam
E.3.35 Comparison of Average Monthly Streamflows
at Gold Creek of the Two Operational Watana
and Devil Canyon Dams
E.3.36 Comparison of Average Monthly Streamflows at
Sunshine of the Two Operational Watana and
Devil Canyon Dams
E.3.37 Comparison of Average Monthly Streamflows
at Susitna of the Two Operational Watana
and Devil Canyon Dams
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LIST OF TABLES
E.3.38 Impact Issues and Proposed Mitigation
Features for Anticipated Filling and
Operational Impacts to Aquatic Habitats
Susitna Hydroelectric Project
£.3.39 Proposed Fisheries Mitigations with Estimated
Capital and Annual Operating and Maintenance
Costs
E.3.40 Schedule for Implementing Fisheries
Mitigation Program
E.3.41 Construction Costs for Water Quality
and Fisheries Monitoring in 1982 Dollars
from 1985 to 2002
E.3.42 Alaska Department of Fish and Game Standards
for Passing Arctic Grayling to be Used on
Susitna Hydroelectric Project Stream Crossings
E.3.43 Alaska Department of Fish and Game Temporary
Stream Diversion Standards
E.3.44 Alaska Department of Fish and Game Standards
for Blasting Near an Anadromous Fish Stream
E.3.45 Cost Assumptions Used in Developing Estimated
Costs for Fisheries Mitigation
E.3.46 Estimated Square Feet of Salmon Spawning
Habitat Made Available by Mitigation
Procedures
E.3.47 Annual Operating Costs of Fisheries
Monitoring Program in 1982 Dollars
E.3.48 Vascular Plant Species in the Watana
and Gold Creek Watersheds and Downstream
Floodplain Which Are Outside Their Range
E.3.49 Candidate Endangered and Threatened Plant
Taxa Sought in the Watana and Gold Creek
Watershed Surveys with Notes on Their
Habitats and Known Localities
E.3.50 Vegetation Types (and sample location numbers)
Sampled in Watana and Gold Creek Watersheds
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LIST OF TABLES
E.3.51 Hectares and Percentage of Total Area Covered
by Vegetation Types in the Watana and Gold Creek
Watersheds
E.3.52 Hectares and Percentage of Total Area
Covered by Vegetation Types for the Area
16 km on Either Side of the Susitna River
From Gold Creek to the Maclaren River
E.3.53 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Open Conifer Vegetation Type in Watana
and Gold Creek Watersheds
E.3.54 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in Open
White Spruce Vegetation Type in Watana
and Gold Creek Watersheds
E.3.55 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Open Black Spruce Vegetation Type in
Watana and Gold Creek Watersheds
E.3.56 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Woodland Conifer Vegetation Type in Watana
and Gold Creek Watersheds
E.3.57 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in .
Closed Balsam Poplar Forest Vegetation
Type in Watana and Gold Creek Watersheds
E.3.58 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Closed Birch Deciduous Forest Vegetation
Type in Watana and Gold Creek Watersheds
E.3.59 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Closed Aspen Deciduous Vegetation Type
in Watana and Gold Creek Watersheds
E.3.60 Cover Percentages for Total Vegetation~
Vertical Strata, and Plant Species in Open
Mixed Conifer-Deciduous Forest Vegetation
Type in Watana and Gold Creek Watersheds
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LIST OF TABLES
E.3.61 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Closed Mixed Conifer-Deciduous Forest
Vegetation Type in Watana and Gold Creek
E.3.62 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in Wet
Sedge-Grass Tundra Vegetation Type in
Watana and Gold Creek Watersheds
E.3.63 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Mesic Sedge-Grass Tundra Vegetation
Type in Watana and Gold Creek Watersheds
E.3.64 Plant Species List of One Herbaceous
Alpine Tundra Stand in Watana and Gold
Creek Watersheds
E.3.65 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Closed Mat and Cushion Tundra Vegetation
Type in Watana and Gold Creek Watersheds
E.3.66 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Closed Tall Alder Vegetation Type in
Watana and Gold Creek Watersheds
E.3.67 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Open Tall Alder Vegetation Type in Watana
and Gold Creek Watersheds
E.3.68 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in
Closed Low Shrub Vegetation Type in
Watana and Gold Creek Watersheds
E.3.69 Cover Percentages for Total Vegetation,
Vertical Strata, and Plant Species in Open
Low Shrub Vegetation Type in Watana and
Gold Creek Watersheds
E.3.70 Aquatic Plant Survey, Susitna Hydroelectric
Project, August 1980
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LIST OF TABLES
E. 3. 71 Hectares and Percentage of Tota 1 Area Covered
by Vegetative Community Types in the Watana
Watershed
E.3.72 Hectares and Perc€ntage of Total Area
Covered by Vegetative Community Types
in the Gold Creek Watershed
E.3.73 Percent Cover in Early Successional Stands
on Downstream Foodpl~in of Susitna River
E.3.74 Percent Cover in Alder Stands on Downstream
Floodplain of Susitna River
E.3.75 Percent Cover in Immature Balsam Poplar Stands
on Downstream Floodplain
E.3.76 Percent Cover in Birch-Spruce Stands on
Downstream Floodplain, Summer 1981
E.3.77 Hectares and Percent of Total Area Covered By
Vegetation Types Within the Healy To Fairbanks
Study Corridor
E.3.78 Hectares and Percent of Total Area Covered by
Vegetati~n Types Within the Willow To Cook Inlet
Study Corridor
E.3.79 Areas of Different Vegetation Types To Be Crossed
by Willow-To-Healy Transmission Corridor
E.3.80 Areas of Each Vegetation Type to Be Crossed by
Watana-To-Go]d Creek Transmission Corridors and
Percent Total for Watana and Gold Creek Watersheds
E.3.81 Vegetation and Wetland Class~s Found in the Proposed
Susitna Impoundment and Borrow Areas
£.3.82 Hectares of Different Wetland Types by Project
Component
E.3.83 Hectares of Gifferent Vegetation Types to be
Affected by the Watana Facility Compared with
Total Hectares of That Type Upstream of Gold
Creek in the Susitna Watershed and in the Area
Within 16 km of the Susitna River
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LIST OF TABLES
E.3.84 Hectares of Different Vegetation Types to be
Affected by the Devil Canyon Facility Compared
With Tot a 1 Hectares of That Type in the Watana
and Gold Creek Watersheds and in the Area Within
16 km of the Susitna River
E.3.85 Areas of Each Vegetation Type to be Cleared for
Access and Percent Total for Watana and Gold
Creek Watersheds
E.3.86 Areas of Different Vegetation Types to be
Crossed by Transmission Corridors
E.3.87 Comparison Between Aerial Habitat Classifications and
Those of Viereck and· Dyrness (1980) Used to Classify
Observations of Radio-Collared Moose in the Nelchina
and Susitna River Basins of South-Central Alaska from
1977 Through Mid-August
E.3.88 Monthly Use of Habitat Types by Radio-Collared Moose
of Both Sexes and All Ages as Determined From Fixed-Wing
Aircraft from October 1976 Through Mid-August 1981 in
the Middle and Upper Susitna and Nelchina River Basins
E.3.89 Summary of Elevational Use by Approximately 200 Radio
Collared Moose (Both Sexes and All Age Classes) From
October 1976 Through Mid-August 1981 in the Middle and
Upper Susitna and Nelchina River
E.3.90 Occurrence and Mean Percent of Canopy Coverage for Species
of Ri pari an and Non-Ri pari an Vegetation and Habitat Types
Observed at Relocation Sites for 6 Male Moose Captured and
Radio-Collared Along the Susitna River South of Talkeetna,
Alaska, and Monitored During Calving, Summer, Breeding,
and Transitional Periods from March 16 to October 15, 1981
E.3.91 Occurrence and Mean Percent of Canopy Coverage for Species
of Riparian and Non-Riparian Vegetation and Habitat Types
Observed at Relocation Sites for 19 Female Moose Captured
and Radio-Collared Along the Susitna River South of
Talkeetna, Alaska, and Monitored During Calving, Summer,
Breeding, and Transitional Periods from March 16 to
October 15, 1981
E.3.92 Winter Carrying Capacity of the Watana Impoundment Zone
(Including Adjacent Project Facilities) and Susitna
Watershed Upstream of Gold Creek for Moose Based on the
Biomass of Twigs Available in Winter
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LIST OF TABLES
E.3.93 Dates Indicating Chronology of Departure From
Susitna River Wintering Areas for Male and Female
Moose Radio-Collared on the Susitna River Downstream
From Talkeetna, March 10-12, 1981
E.3.94 Minimum, Maximum and Mean Distance to the Susitna
River from Geometri ca 1 Centers of the C.a 1 vi ng
Range, Summer Range, and Breed·ing Range for Male and
Female Moose Radio-Collared in Several Locations
Along the Susitna River Between Devil Canyon and
the Delta Islands, Alaska 1980-81
E.3.95 Proximity to the Susitna River of Relocations of
9 Male and 29 Female Moose Radio-Colla red Along The
Susitna River Between Devil Canyon and the Delta
Islands, Alaska, 1980-81
E.3.96 Summary of Moose Sex and Age Composition Data
Collected Annually in Count Area 6 in Game
Management Unit 13 of Southcentral Alaska
E.3.97 Summary of Moose Sex and Age Composition Data
Collected Annually in Count Area 7 in Game
Management Unit 13 of Southcentral Alaska
E.3.98 Summary of Moose Sex and Age Composition Data
Collected Annually in Count Area 14 in Game
Management Unit 13 of Southcentral Alaska
E.3.99 Summary of Moose Census Data and Subsequent Population
Estimates for Count Areas 7 and 14 Derived from
Surveys Conducted Along the Susitna River From
November 5 through November 8, 1980
E.3.100 Density (Moose/km of River) Of Moose Observed on 10
Aerial Censuses in 4 Zones of Riparian Habitat Along
the Susitna River from Devil Canyon to Cook Inlet,
Alaska, 1981-82
E.3.101 Summary of Moose Sex and Age Composition Data
Obtained During Surveys of Riparian Communities
Along the Lower Susitna River
E.3.102 Proportion of Radio-Collared Caribou Sightings
In Each Vegetation Type
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LIST OF TABLES
E.3.103 Nelchina Caribou Herd Population Estimates
E.3.104 Reported Hunter Harvest of the Nelchina
Caribou Herd, 1972-1981
E.3.105 Compilation of Highest Yearly Counts
Completed in Watana Hills Sheep Trend
Count Area
E.3.106 Number and Age-Sex Classification of Sheep
Observed at Jay Creek Mineral Licks From
May 6 Through June 24, 1981
E.3.107 Number of Aerial Brown Bear Observations By
Month in Each of 5 Major Habitat Categories
E.3.108 Comparison of Reported Home Range Sizes of
Brown/Grizzly Bears in North America
E.3.109 Densities of Selected North American Brown
Bear Populations
L3.110 Averge Age and Sex Ratios of Brown Bear
Populations in the Middle and Upper Susitna
and Nelchina River Basins
E.3.111 Litter Sizes of Various North American
Brown Bear Populations
E.3.112 Reproductive Rates of North American Brown
Bear Populations
E.3.113 Summary of Brown Bear Harvest from Alaska's
Game Management Unit 13, 1973-1980
E.3.114 Nmber of Aerial Black Bear Observations by Month
in Each of 5 Habitat Categories
E.3.115 Summary of Reported Black Bear Harvests From
Alaska's Game Management Unit 13, 1973-1980
E.3.116 Comparisons of Food Remains in Wolf Scats Collected
At Den and Rendezvous Sites in 1980 and 1981 from
the Eastern Susitna Basin and Adjacent Areas
E.3.117 Estimate of Numbers of W,olves by Individual Pack
Inhabiting the Susitna Hydroelectric Study Area in
Spring and Fall 1980 and 1981
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LIST OF TABLES
E.3.118 Number of Sample Units Containing Indicated
Level of Beaver Activity During Summer 1982
Downstream Survey
£.3.119 1982 Aerial Counts of Beaver Structures Along
15.2 Km (9.4 Mi) of Lower Deadman Creek Immediately
Downstream from Deadman Lake, and A Marshy Section
of Upper Deadman Creek From Its Mouth at Deadman
lake 3.2 Km {2.0 Mi) Upstream From The Lake
E.3.120 Results of Surv~ys For Muskrat Pushups Upstream
From Gold Creek During Spring 1980
E. 3.121 Numbers of Furbearer Tracks Seen During Aeri a 1
Transects in the Middle Susitna Basin, November 1980
E.3.122 Tabulation of November 1980 Aerial Transect Data,
Species by Vegetation Type
E. 3.123 Number of Tracks of Otter and M,; nk Observed At
North and South Sides of 37 Susitna River Check
Points, November 10-12, 1980
E. 3.124 Results of Marten Scat Analyses by Season, Based
Upon Percent Frequency of Occurrence
E.3.125 Tracks of Red Foxes Encountered During November 1980
Aerial Transect Surveys
E.3.126 Red Fox Den Classification System
£.3.127 Location and Status of Raptor and Raven Ne$t Sites
in the Middle Susitna Basin, Alaska
E.3.127b Location of Raptor Nests in 'the Middle Susitna
Basin
E.3.128 Breeding Phenologies of Eagles, qyrfalcon, and
Common Raven in Interior Alaska
E.3.129 Data on Bald Eagle Nests Along the Susi.tna River
Between Devil Canyon and Cook Inlet
E.3.13:0-Summary of Total Numbers and Species ComposUion of
Waterbirds Seen on Lakes Surveyed in Summer, 1981 in
the Middle Susitna Basin
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LIST OF TABLES
E.3.131 Summary of Total Numbers and Species Composition of
Waterbirds Seen on Surveyed Waterbodies During
Aerial Surveys of the Upper Susitna River Basin,
Fall 1980
E.3.132 Summary of Total Numbers and Species Composition of
Waterbirds Seen on Surveyed Waterbodies During Aerial
Surveys of the Upper Susitna River Basin, Fall 1981
E.3.133 Summary of Total Numbers and Species Composition of
Waterbirds Senn on Surveyed Waterbodies During Aerial
Surveys of the Upper Susitna River Basin, Spring 1981
E.3.134 Seasonal Population Stat~stics for the More Important of
Surveyed Waterbodies of the Middle Susitna River Basin,
1980-81
E.3.135 Summary of Total Numbers and Species Composition of
Waterbirds Seen During Spring Aerial Surveys of the
Lower susitna River, 1981 and 1982
E.3.136 Number of Territories of Each Species on Each 10-
Hectare Census Plot, Upper Susitna River Basin,
Alaska, 1981
E.3.137 Number of Territories of Each Bird Species on Each 10-
Hectare Census Plot, Upper Susitna River Basin,
Alaska 1981
E.3.138 Comparison of Breeding Bird Densities, 1981 and 1982,
Middle Susitna River in Alaska
E.3.139 Habitat Descriptions of 10 Ha Avian Census Plots
E.3.140 Major Avian Habitats of the Middle Susitna Basin and
Their Most common Avian Species
E.3.141 Relative Abundance of Birds by Habitat and Vegetation
Succession Stage, Lower Susitna River Floodplain,
June 10-21, 1982. Figures Are the Number of Birds
Recorded Per 100 Minutes in Each Habitat
E.3.142 Number of Small Mammels Captured Per 100 Trap Nights
During Four Sampling Periods Between August 1980 and
August 1982, Middle Susitna River Basin
xii
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LIST OF TABLES
E.3.143 Standardized Habitat Niche Breadth Values For Ten
Small Mammal Species Sampled by Snap and Pitfall
Trapping at 43 Sites, Middle Susitna River Basin,
Fall 1981
E.3.144 Time Schedule of Anticipated Impacts to Terrestrial
Vertebrates Resulting From Susitna Hydro Project
E.3.145 Anticipated and Hypothesized Impacts to Moose
E.3.146 Loss of Cover Types Commonly Used By Moose,
In Relation To Their Availability
E.3.147 Anticipated and Hypothesized Impacts to Caribou
E.3.148 Anticipated and Hypothesized Impacts to Dall Sheep
E.3.149 Anticipated and Hypothesized Impacts to Brown Bears
E.3.150 Anticipated and Hypothesized Impacts to Black Bear
E.3.151 Anticipated and Hypothesized Impacts to Wolves
E.3.152 Anticipated and Hypothesized Impacts to Wolverine
E.3.153 Anticipated and Hypothesized Impacts to
Aquatic Furbearers {Beaver and Muskrat)
E.3.154 Number of Lakes With Muskrat Pushups in Spring 1980
Occurring Within Borrow Areas and Impoundments
E.3.155 Anticipated and Hypothesized Impacts to Semi-
Aquatic Furbearers
E.3.156 Anticipated and MYpothesized Impacts on Fox
E.3.157 Anticipated and Hypothesized Impacts to Marten,
Weasel, and Lynx
E.3.158 General Types of Impacts to Raptors
E.3.159 Anticipated and Hypothesized Impacts to Raptors
and Ravens
xiii
LIST OF TABLES
E.3.160 Number of Known Raptor or Raven Nest Sites in the
Middle Susitna River Basin, Alaska, That Would Be
Inundated by the Watana and Devil Canyon Reservoirs
or That May Be Affected by Development of Associated
Access Routes and Transmission Routes
E.3.161 Raptor and Raven Nesting Locations in the Middle
Susitna Basin, Alaska, That May Be Affected By The
Susitna Hydroelectric Project Development
E.3.162 Nest Number and Status of Raptor Nesting Locations
Which Will Be Affected by the Susitna Hydro Project
and the Source of Impacts
E.3.163 Factors That Affect the Sensitivity of Raptors to
Disturbances
E.3.164 Influence of Timing of Disturbance on the Possible
Effects on Raptors
E.3.165 Approximate Losses of Avian Habitats Studied in the
Middle Susitna Basin as a Result of the Susitna
Hydroelectric Project
E.3.166 Estimated Number of Small and Medium-Sized Birds That
Would Be Eliminated Through Habitat Destruction As a
Result of the Susitna Hydroelectric Project
E.3.167 Total Average Daily Traffic on Access Road and Denali
Highway During Peak Construction Year and Season
E.3.168 State of Alaska Temporal and Spatial Protection Criteria
For Nesting Raptors
E.3.169 Estimated Mitigation .Costs for Compensation for Moose,
Brown Bear and Black Bear Foraging Habitat Loss
E.3.170 Estimated Mitigation Costs for Aerial Photography of
Vegetation in the Downstream Floodplain
E.3.171 Estimated Mitigation Costs for Bald Eagle Habitat
Modification
E.3.172 Estimated Mitigation Costs for Design, Construction,
and Placement of 10 Nest Platforms with Artificial
Nests for Golden Eagles
xiv
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LIST OF TABLES
E.3.173 Estimated Mitigation Costs for Design, Construction,
and Placement of 10 Nest Boxes for Cavity-Nesting
Raptors
E.3.174 Estimated Mitigation Co~ts for Modification of Cliff
Locations to Provide Golden Eagle Nesting Habitat
E.3.175 Estimated Mitigation Costs for Creating New Nesting
Cliffs for Golden Eagles
E.3.176 The Success of Artificial Nesting Structures Installed
On Power Poles and Transmission Towers
E.3.177 Botanical Resources Mitigation Summary
E.3.178 Wildlife Mitigation Summary
XV
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LIST OF FIGURES
E.3.1
E.3.2
E. 3. 3
E.3.4
E.3.5
E.3.6
E. 3. 7
E. 3. 8
E. 3. 9
Option An a 1 ys is
Relationship of Field Studies and rvbnitoring
to Impact Assessment and Mitigation Planning
Susitna River Drainage Basin
Susitna River and Major Tributaries From
Mouth to Little Willow Creek
Susitna River and Major Tributaries From
Montana Creek to Devil Canyon
Susitna River and Major Tributaries from
Devil Canyon to Denali Highway
Upper Cook Inlet Commercial Salmon Managenent
Area
Population Estimates of .Adult Salmon in
Susitna River
Percentage of Salmon Migrating Past Sunshine
E.3.10 Timing of Life Stages of Salmon in the Susitna
Rivr From Talkeetna to Devil Canyon
E.3.11 Daily Sonar Counts of Sockeye Salmon At Susitna,
Yentna, Sunshine and Talkeetna Stations
E.3.12 Slough and Tributary Index Area Peak Spawning Counts
E • 3. 13 S 1 o ug h and T r i b ut a r y In d ex Ar e a Pe a k Sp awn i n g Co un t s
E.3.14 Slough and Tributary Index Area Peak Spawning Counts
E.3.15 Slough and Tributary Index Prea Peak Spawning Counts
E.3.16 Slough and Tributary Index Area Peak Spawning Counts
E.3.17 Sl ot.gh and Tributary Index Area Peak Spawning Counts
E.3.18 Daily Sonar Counts of Ch1J11 Salmon at Susitna, Yentna,
Sunshine and Ta.lkeetna Stations
E.3.19 Daily Sonar Counts of Coho Salmon at Susitna, Yentna,
Sunshine and Ta.lkeetna Stations
xvi
LIST OF FIGURES
E.3.20 Daily Sonar Counts of Pink Salmon at Susitna,
Yentna, Sunshine and Talkeetna Stations
E.3.21 Waterbodies To Be Inundated By Watana Reservoir
E.3.22 Fish Spawning Times Vs. Watana
Surface Elevation
E.3.23 Waterbodies To be Inundated By Devil Canyon
Reservoir
E.3.24 Diagram of Fish Stream Crossing
E.3.25 Rehabilitated Tsusena Creek Borrow Site
E.3.26 Berm Design to Prevent Overtopping of Sloughs
E.3.27 Slough Mouth Restructured Plan
E.3.28 Design Drawing of Lowered and Restructured Slough
E.3.29 Susitna River Fishery Mitigation Induced
Upwelling Using Tributary Water Supply
E.3.30 Susitna River Fishery Mitigation Main Stream
Spawning Bed
E.3.31 Schematic Grayling Hatchery
E.3.32 Study Area for Botanical Resources and Wildlife
E.3.33 Vegetation Mapping Areas of the Susitna
River Basin
E.3.34 Locations of Stands Sampled on Downstream
Floodplain of the Susitna River, 1981
E.3.35 Vegetation Mapping Areas for Transmission Corridors
E.3.36 The Watana and Gold Creek Watersheds With Major
Water Bodies
E.3.37 Location of Project Facilities
E.3.38 Vegetation Map of Upper Susitna River Basin
E.3.39 Vegetation Map of Susitna Project Impact Areas
xvii
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LIST OF FIGURES
E.3.40 Vegetation Map of Susitna Project Impact Areas
E.3.41 Vegetation Map of Susitna Project Impact Areas
E.3.42 Vegetation Map of Proposed Susitna Hydroelectric
Access Corridors
E.3.43 Vegetation Map of Proposed Susitna Hydroelectric
Access Corridors
E.3.44 Vegetation Map of Proposed Susitna Hydroelectric
Access Corridors
E.3.45 Wetland Map of Susitna Hydroelectric Project
Access Corridors
E.3.46 Wetland Map of Susitna Hydroelectric Project
Access Corridors
E.3.47 Wetland Map of Susitna Hydroelectric Project
Access Corridors
E.3.48 Vegetation Map of Proposed Healy-Fairbanks
Transmission Corridor
E.3.49 Vegetation Map of Proposed Healy-Fairbanks
Transmission Corridor
E.3.50 Vegetation Map of Proposed Healy-Fairbanks
Transmission Corridor
E.3.51 Vegetation Map of Proposed Willow-
Cook Inlet Transmission Corridor
E.3.52 Vegetation Map of Proposed Willow-
Cook Inlet Transmission Corridor
E.3.53 Vegetation Map of Susitna Project Impact Areas
£.3.54 Vegetation Map of Susitna Project Impact Areas
E.3.55 Vegetation Map of Susitna Project Impact Areas
E.3.56 Vegetation Map of Susitna Project Impact Areas
E.3.57 Vegetation Map of Susitna Project Impact Areas
xviii
LIST OF FIGURES
E.3.58 Vegetation Map of Susitna Project Impact Areas
E.3.59 Vegetation Map of Susitna Project Impact Areas
E.3.60 Vegetation Map of Susitna Project Impact Areas
E.3.61 Vegetation Map of Susitna Project Impact Areas
E.3.62 Vegetation Map of Susitna Project Impact Areas
E.3.63 Vegetation Map of Susitna Project Impact Areas
E.3.64 Vegetation Map of Susitna Project Impact Areas
E.3.65 Vegetation Map of Susitna Project Impact Areas
E.3.66 Wetland Map of Susitna Hydroelectric Project
Impoundment Area and Borrow Sites
E.3.67 Wetland Map of Susitna Hydroelectric Project
Impoundment Area and Borrow Sites
E.3.68 Wetland Map of Susitna Hydroelectric Project
Impoundment Area and Borrow Sites
E.3.69 Wetland Map of Susitna Hydroelectric Project
Impoundment Area and Borrow Sites
E.3.70 Wetland Map of Susitna Hydroelectric Project
Impoundment Area and Borrow Sites
E.3.71 Wetland Map of Susitna Hydroelectric Project
Impoundment Area and Borrow Sites
E.3.72 Wetland Map of Susitna Hydroelectric Project
Impoundment Area and Borrow Sites
E.3.73 Wetland Map of Susitna Hydroelectric Project
Impoundment Area and Borrow Sites
E.3.74 Vegetation Sample Locations in Susitna River
Basin, 1980
E.3.75 Locations of Lakes and Ponds Surveyed for Vascular
Aquatic Plants in August 1980
E.3.76 A Schematic Representation of the Dominant Vegetation
Associated With Many of the Lakes and Ponds of the
Susitna Basin
xix
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LIST OF FIGURES
E.3.77 Patterns of Forest Succession Following
Fire In Alaska
E.3.78 Primary Succession on the Susitna Floodplain
E.3.79 Adjustments to Road/Railroad Alignments
Index Map
E.3.80 Adjustments to Road Alignment
E.3.81 Adjustments to Road Alignment
E. 3. 82 Adjustments to Road and Rai 1 road Alignments
E.3.83 Comparison of Road Construction Techniques
E.3.84 Typical Hillside Cut of Railroad Cross Section
E.3.85 Typical Transmissi~n Right-of-Way Cross Section
E.3.86 Locations of Radio-Collared Cow Moose During
Parturition (May 15-June 15) From 1977 Through 1981
E.3.87 Locations of Radio-Collared Moose During The Rut
(September 20-0ctober 20) From 1977 Through Fall 1980
E.3.88 General Movement and Migration Patterns of Radio-
Collared Moose From October 1976 Through Mid-August 1981
E.3.89 Boundaries of Established Moose Count Areas
E.3.90 Zones Employed To Estimate Moose Densities Within
Riparian Communities Along the Susitna River
E.3.91 Dates of Mortalities of Collared and Uncollared Moose
Calves During 1977, 1978 and 1980 In The Nelchina and
Upper Susitna Basin, Alaska
£.3.92 Historical Range of the Nelchina Caribou Herd
E.3.93 Distribution of Nelchina Radio-Collared Caribou During
Calving Period, May 15 Through June 10, 1980 and 1981
E.3.94 Location of Radio-Collared Caribou In Subherds,
May 9, 1980, Through September 22, 1981
E.3.95 Seasonal Elevation Use By Caribou From Nelchina Head
XX
LIST OF FIGURES
E.3.96 Calf Survival Compared to Wolf Numbers
And Total Caribou
E.3.97 Location of Dall Sheep Study and Aerial
Survey Areas
E.3.98 Suspected Locations and Territorial Boundaries
Of Wolf Packs Inhabiting The Susitna Hydroelectric
Project Area during 1980 and 1981
E.3.99 General Location and Year of Use of Observed Wolf
Den and Rendezvous Sites Discovered in the Susitna
Hydroelectric Project Area From 1975 Through 1981
E.3.100 Observed Home Ranges of ~olverines In The Middle
Susitna Basin Based on Location of Radio-Collared
· Animals
E.3.101 Aerial Transects for Furbearers and Checkpoints
For Otter and Mink Sign
E.3.102 Locations and Classification of Fox Dens
E.3.103 Locations of 12 Bird Census Plots in the Middle
Susitna River Basin
E.3.104 Locations of Important Lakes and Lake Groups
Surveyed for Waterfowl in the Middle Susitna
Basin
E.3.105 Importance Values of Waterbodies for Migrant
Waterfowl in the Middle Susitna Basin, Upper
Tanana River Valley, and Scottie Creek Area
Fall 1980
E.3.106 Importance Values of Waterbodies for Migrant
Waterfowl in the Middle Susitna Basin, Upper
Tanana River Valley, and Scottie Creek Area
Spring 1981
E.3.107 Clustering of 42 Small Mammal Trapline Sites
Into Similar Vegetative Groupings, Based on an
Analysis of Frequency Counts of 81 Plant Taxa
In the Ground Cover
E.3.108 Abundance Patterns of Eight Small Mammal Species
Relative To Vegetation Types at 42 Sites in the
Susitna River Basin, Alaska, July 29-August 30, 1981
xxi
-
LIST OF FIGURES
E.3.109 Probable Factors Regulating Moose Populations in the
Susitna Basin and Actions That Might Affect These
Populations
E.3.110 Probable Factors Regulating Brown Bear Populations
in the Susitna Basin and Actions That Might Affect
These Populations
E.3.111 Probable Factors Regulating Black Bear Populations
in the Susitna Basin and Actions That Might Affect
These Populations
E.3.112 Probable Factors Regulating Wolf Populations in the
Susitna Basin and Actions That Might Affect These
Populations
E.3.113 Probable Factors Regulating Beaver Populations in the
Susitna Basin and Actions That Might Affect These
Populations
E.3.114 Probable Factors Regulating Marten Populations in the
Susitna Basin and Actions That Might Affect These
Populations
E.3.115 Elevations of Raptor and Raven Nests in the Vicinity
of the Watana Impoundment Area in Relation to Filling
and Operation Water Levels
E.3.116 Changes in Elevation of the Devil Canyon Reservoir
During Operation and Elevations of Raptor and Raven
Nests ·in the Proximity of the Impoundment Zone
E.3.117 Relative Amounts of Moose Browse Available Compared
With The Time Since Fire or Other Disturbance in
Interior Alaska
E.3.118 Eagle Nesting Platforms to be Provided on Transmission
towers
E.3.119 Ground Wire Gapping Designed to Protect Raptors From
Electrocution
E.3.120 Armless Configurations Designed to Protect Raptors
From Electrocutions
E.3.121 Installation of Transformer Equipment to Provide for
Raptor Perching
xxii
LIST OF FIGURES
E.3.122 Perch Guards Designed to Protect Raptors From
Electrocution
E.3.123 Elevated Perch Construction Designed to
Protect Raptors from Electrocution
xxiii ~I
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3 -FISH, WILDLIFE, AND BOTANICAL RESOURCES
1 -INTRODUCTION
This report discusses the fish, vegetation, and wildlife resources of
the area that wi 11 be affected by the proposed Susi tna Hydroelectric
Project. Each of the major subsections (2 -Fish, 3 -Botanical
Resources, and 4-Wildlife) provides a baseline description of species
and populations of the project area; an assessment of potential project
impacts on this biota (assuming no mitigation); and a mitigation plan
that explains how preliminary engineering design and construction plan-
ning have incorporated measures to avoid, minimize, or rectify poten-
tially adverse effects of the project on the biological environment.
In appropriate cases, resource management options to reduce or
compensate for adverse impacts that can not otherwise be mitigated are
discussed.
1.1-Baseline Descriptions
These sections describe the di stri buti ons and characteristics of bi o-
1 ogi cal populations and communities within the project area. The dis·-
cussions are based on a thorough review of the scientific literature
and emphasize documented studies conducted in preparation for the
Susitna Hydroelectric Project by the Alaska Department of Fish and Game
and professional consultants. They provide the most current available
information through December 1982 on fish, vegetation, a.nd wildlife of
the project area.
Di scussi ons of ani rna 1 s focus on vertebrate species: resident and anad-
romous fish, big game, furbearers, birds, and non-game (small} mammals.
The plant descriptions deal with species aggregations that occur in
recognizable patterns, such as vegetation communities and successional
stages.·
The baseline descriptions emphasize functional rel ati onshi ps among
habitat components and animal communities. Factors that regulate
species di stri buti on and abundance receive particular attention,
because knowledge of these regulating mechanisms can suggest where
populations are most sensitive to potential disturbance. For example,
water temperature and stream regimes are discussed as regulators of
fish populations, and the role of plant communities in regulating wild-
life populations is ex ami ned.
1.2 -Impact Assessments
It is expected that the di stri buti on and abundance of fish, plant, and
wildlife species in and around the area of the Susi tna Hydroelectric
Project wi 11 change as a result of project construction and operation.
E-3-1
1.2 -Impact Assessments
The impact assessments presented in this report are based, in part, on
the project description presented in Ex hi bit A, project operations des-
cribed in Exhibit B, the proposed construction schedule shown in
Exhibit C, and an analysis of similar activities associated with large
construction and hydroelectric projects in similar habitats. In addi-
tion, the Recreation Plan presented in Exhibit E, Chapter 7, has been
reviewed as a proposed project action to determine its potential
impacts on fish, vegetation, and wildlife. The impact assessments link
predicted physical changes with habitat utilization to provide a quali-
tative statement of impacts likely to result from the Susitna Hydro-
electric Project. Quantitative assessments are presented where justi-
fied by current knowledge and research techniques. Changes potentially
resulting from the project are discussed with respect to specific proj-
ect features and activities, assuming standard engineering design and
construction practice without the incorporation of mitigation measures.
Much of the discussion is based on professi anal judgment. Data collec-
tion and analysis programs currently underway wi 11 refine several of
the impact assessments as expl~ned in the text.
Although some project impacts, if not mitigated, wi 11 be adverse, other
impacts will be innocuous and some wi 11 enhance fish or wildlife pro-
ductivity. Therefore, potentially beneficial impacts are given bal-
anced treatment with those to be mitigated. Each potential effect,
together with the action responsible for it, is called an impact
issue.
The identification and prioritization of impact issues have followed
the procedures established by the Susi tna Hydroelectric Project Fish
and Wildlife Mitigation Policy (Alaska Power Authority 1982; Appendix
3.A). This policy was prepared by the Power Authority through a
Fisheries Mitigation Core Group, a Wildlife Mitigation Core Group, and
a Fish and Wildlife Mi ti gati on Review Group. The core groups, consi s-
ting of professi anal consultants and agency representatives, developed
the technical specifics of the mitigation policy. The review group,
which consists entirely of state and federal agency representatives,
evaluated draft stages of the mitigation policy and provided comments
that were incorporated through successive revisions. The review group
included representatives of the following resource agencies:
-Alaska Department ofFish and Game (ADF&G);
-Alaska Department of Natural Resources (ADNR);
-National IVJari ne Fisheries Service (NMFS);
U.S. Bureau of Land Management (USBLM);
-U.S. Environmental Protection Agency (USEPA); and
-U.S. Fish and Wildlife Service (USFWS).
In addition to procedures outlined in the Susitna Hydroelectric Project
mitigation policy, criteria for assessing the relative importance of
biological impact issues have been provided by (1) mitigation policies
of the Alaska Department of Ash and Game (1982a) and the U.S. ~ sh and
E-3-2
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1. 3 -Mi t i gat i on P l an s
Wildlife Service (1981); (2) letters and testimony by the Alaska
Department of Fish and Game (1980, 1982b, 1983), the Alaska Department
of Natural Resources (1982), the U.S. Fish and Wildlife Service {1979,
1980, 1981a, 1981b, 1982a-d, 1983), and the Susi tna Hydroelectric
Steering Committee (1981, 1982); and (3) discussions of impact issues
in workshops (ESSA/WELUT/LGL 1982) and numerous other technical meet-
ings involving Susitna project personnel and resource agency represen-
tatives.
All three mitigation policies imply that project impacts on the habi-
t at s of certain sensitive fish and wildlife species will be of greater
concern than changes in distribution and abundance of less sensitive
species. Sensitivity can be related to high human use value as well as
susceptibility to change because of project impacts. The policies and
comments also indicate that, for the Susitna Project area, vegetation
is considered more important as a component of wildlife habitat than as
a botanical resource in itself. Statewide policies and management
approaches of resource agencies suggest that concern for fish and wild-
li fe species with commercial, subsistence, and other consumptive uses
is greater than for species without such value. These species are
often large, sometimes numerous, and utilize a wide range of habitats,
as well as having high human use value. Such characteristics often
result in these species being selected for careful evaluation when
their habitats are subjected to alternative uses. By avoiding or mini-
mizing alterations to habitats utilized by these evaluation species,
the impacts to other less sensitive species that utilize similar habi-
tats can also be avoided or reduced.
The mitigation po li ci es all agree that resource vulnerability is an
important criterion for impact prioritization. Resources judged most
vulnerable to potential project impacts have therefore been given high-
est priority in impact assessment and mitigation planning. Similarly,
impact issues have been considered with regard to probability of occur-
rence. Where there is a high degree of confidence that an impact will
actually occur, it has been ranked above impacts that are predicted to
be less likely to occur. Also, the mitigation policies and agency com-
ments indicate that impacts on animal productivity and population size
through changes in habitat availability are of high concern. Behav-
ioral responses that have the potential for producing population-level
effects are also important. Adverse impacts that are longer lasting or
irreversible have priority over short-term impacts.
1.3-Mitigation Plans
Mitigation plans have been developed for identified impact issues in
accordance with the sequence of steps defined by 40 CFR 1508.20, pur-
suant to the National Environmental Policy Act (42 USC 4321 et seq.).
E-3-3
1.3 -Mi ti gati on Plans
The mitigation planning sequence includes, in priority order of imple-
mentation, the following steps:
-Avoiding the impact through project design and operation, or by not
taking a certain action;
-Mini mi zing the impact by reducing the degree or magnitude of the
action, or by changing its location;
-Rectifying the impact by repairing, rehabi li tati ng, or restoring the
affected portion of the environment;
Reducing or eliminating the impact over time by preservation, moni-
toring, and maintenance operations during the life of the action;
and
-Compensating for the impact by providing replacement or substitute
resources that would not otherwise be avail able.
This sequential strategy for mi ti gati on option analysis and i mplementa-
tion is shared by all three mitigation policies applied to the project
(Alaska Power Authority 1981, ADF&G 1982a, USFWS 1981). The relation-
ships of steps within the sequence are shown in Figure E .3.1 and fur-
ther compared in Table E.3.1.
The process by which mi ti gati on wi 11 be implemented and continually
refined throughout the life of the project is shown schematically in
Figure E.3.2. The process involves the following steps:
-Impact issue evaluation:
. Identi fi cation of the nature and extent of impacts:
Populations
Subpopulations
Habit at types
Geographical areas
Priori ti zati on of impacts:
Ecological value of affected resource
Consumptive value of affected resource
Resource vulnerability
Confidence of impact prediction
Long-term vs. short-term impacts
-Option analysis procedure:
Identification of practicable mitigation options:
Type of mitigation option
.. Sequence of implementation
E-3-4
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1.3 -Mitigation Plans
. Evaluation of mitigation options:
Effectiveness of option
.. Conflicts with project objectives
.. Residual impacts
. Documentation of option analysis:
Impact issues
.. Mi ti gati on options
.. Conflicts (if any) with project objectives
-Mi t i gat i on p 1 an i mp 1 ement at i on:
• Engineering design and construction planning:
Participate in design deve 1 opment
Participate in preconstruction field surveys and site
evaluations
Review de~gns, schedules, permit applications
Construction and operation monitoring:
Review work accompli shed
Evaluate degree of impact
Evaluate effectiveness of mitigation
Identify modi fi cations to the mi ti gati on plan
Submit regularly scheduled reports
Mitigation plan modifications:
Propose modi fi cations
Submit modifications for review
Implement and monitor approved modifications
Oat a from the baseline, impact, and monitoring studies wi 11 be used
throughout the life of the project by the mitigation core and review
groups to plan and continually ref·i ne the mitigation process in a flex-
; ble, adaptive fashion.
Mitigation measures proposed for the Susitna Hydroelectric Project may
be cl assi fi ed within two broad categories:
-Modifications to design, construction, or operation of the project;
and
-Resource management strategies.
The first type of mitigation measure is project-specific and emphasizes
the avoidance, minimization, rectification, or reduction of adverse
impacts, as prioritized by the Fish and Wildlife Mitigation Policy
established by the Power Authority (1982) and coordinating agencies
(ADF&G l982a, USFWS 1981). As shown in Figure -E.3.1, these measures
must first be implemented to keep adverse impacts to the minimum
E-3-5
1.3 -Mitigation Plans
consistent with project requirements. They involve adjusting or adding
project features during design and p 1 anni ng so that mi ti gati on becomes
a b~ lt-in component of project actions.
When impacts cannot be fully avoided or rectified, reduction or compen-
sation measures are justified. This type of mitigation can involve
management of the resource itself, rather than adjustments to the proj-
ect, and will require concurrence of resource ~anagement boards or
agencies with juri sdi cti on over 1 ands or resources within and around
the project area.
Mitigation planning for the Susitna Hydroelectric Project has empha-
sized both approaches. The prioritized sequence of options from avoid-
ance through compensation has been applied to each impact issue. If
full mitigation can be achieved at a high priority option, lower
options may not be considered. In the resulting mitigation plans,
measures to avoid, minimize, or rectify potential impacts are treated
in greatest det ai l. Specifications for f aci l i ty siting and design,
speci a 1 mi ti gati on faci li ties, construction procedures, and scheduling
of project actions to mitigate adverse effects on the biota are pre-
sented. Guidelines for these specifications are summ~rized in Appendix
3.A.
Monitoring and maintenance of mi ti gati on features to reduce impacts
over time are recognized as an integral part of the mitigation
process. The monitoring program will be developed during detailed
engineering design and construction planning and wi 11 apply to fish,
botanical resources, and wildlife.
Long-term management strategies for impact mi ti gati on are discussed as
potential options. The Power Authority is committed to evaluate and
recommend such resource management options, and is sponsoring continu-
ing research to define their need and application. Final agreement on
measures wi 11 require interagency coordination.
E-3-6
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2 -FISH RESOURCES OF THE SUSITNA RIVER DRAINAGE
2.1-Overview of the Resources
2. 1.1 ""' Description of the Study Area for Fish Resources
The study area for the Susitna Hydroelectric Project fish studies
includes the Susitna River mainstem, side channels, sloughs, and
mouths of major tributaries (Figure E.3.3). From the terminus of
Susitna Glacier in the Alaska Mountain Range to its mouth in Cook
Inlet, the Susitna River flows approximat2ly 318 miles (530 km)
and drains 19,600 square miles (50,900 km ). The mainstem and
major tributaries of the Susitna River, including the Maclaren,
Chulitna, Talkeetna and Yentna Rivers, originate in glaciers ·and
carry a heavy load of glacial flour during the ice-free months.
There are many smaller, clear water tributaries that are
perennially silt-free, except during floodflows, including Tyone
River, Oshetna River, Portage Creek, Indian River, Kroto Creek
(Deshka River) and Alexander Creek (Figures E.3.4 to E.3.6).
Streamflow is characterized by moderate to high flows between May
and September and 1 ow flows from October to April. High surrmer
discharges result from snowmelt, rainfall and glacial melt.
Winter flows are almost entirely ground water inflow (see Chapter
2, Section 2.2.3). Freezeup begins in the higher regions in
early October, and most of the river is ice free by late May.
Three study reaches have been defined for baseline data gathering
and impact analysis based.upon stream morphology, flow regime and
anticipated impacts. These study reaches are: the impoundment
from the Oshetna River (River ~ile [RM] 236) to Devil Canyon (RM
152), Devil Canyon to Ta.lkeetna (RM 98); and Ta.lkeetna to Cook
I n 1 et ( RM 0 ) •
2.1.2 -Data Collection and Analysis Methods
(a) Anadromous Adult Investigations
Methods uti 1 i zed during 1981 and 1982 to enumerate adult
salmon within the Susitna River drainage included side-scan
sonar monitoring, fishwheel monitoring, tag and recapture
estimates and ground/aerial spawning surveys.
Side-scan sonars and fi shwheel s were used to determine the
upstream migration timing of sockeye, pink, chum, and coho
salmon in the Susitna River from July through early to mid-
September 1981 and 1982 at Susitna Station (RM 26), Yentna
Station (Yentna RM 04), Sunshine Station (RM 80) and
Talkeetna Station (RM 103) (ADF&G 1982a, Figures E.3.4 and
E.3.5). The species composition of the daily catch of a
nearby fishwheel was used to apportion side scan sonar
counts. Fishwheels were also operated at Curry Station (RM
120), but without associated sonar counters.
2.1 -Overview of Resources
The side-scan sonar counts recorded at Susitna Station were
not used for defining Susitna River salmon escapements be-
cause of suspected inaccuracy of counts caused by counter
siting problems. Details of these problems are discussed in
ADF&G (1983). Yentna Station (RM 04) sonar counts were con-
sidered suitable for reporting 1981 and 1982 Yentna River
salmon escapements (ADF&G 1983).
A tag/recapture program was conducted to estimate numbers of
the five salmon species passing upstream of Sunshine,
Talkeetna and Curry Stations during 1981 and 1982 (ADF&G
1981a, 1982e). Salmon captured by fishwheels at the above
sampling sites were measured, scales were removed for aging,
then the fish were fitted with tags, color-coded for each
site and released. Personnel surveyed all known and sus-
pected salmon spawning tributaries (15) and sloughs (34)
from RM 101.4 to 148.8 of the Susitna River at weekly inter-
vals from 1 ate July through early October. All tagged and
untagged salmon were counted. Species population estimates
were then calculated from survey and fishwheel catch data at
each station.
Salmon abundance within the entirety of sloughs and selected
tributary index reaches was determined by the above surveys
during 1981 and 1982. The tributary index reaches were
within 0.5 mile (0.8 km) of the confluence with the Susitna
River.
Spawning chinook salmon were counted from helicopters during
1981 and 1982 in the Indian River (RM 128.6) and Portage
Creek (RM 148.8). Cheechako Creek (RM 152.5) and an unnamed
creek (RM 156.8) were also surveyed in 1982. Other Susitna,
Chulitna, and Talkeetna River drainage chinook salmon spawn-
ing areas were surveyed as part of an ongoing project since
1975 to determine chinook salmon escapement trends in the
Cook Inlet drainage (ADF&G 1982a). The suitability of heli-
copter surveys as a census method for chinook salmon is dis-
cussed in Neilson and Green (1981) • •
;
Sockeye, chum, pink and coho salmon spawning activity in
mainstem, side-channel, and tributary confluence locations
of the lower and middle Susitna River was evaluated by a
variety of techniques during 1981 and 1982 including: ob-
servation, electroshocking, drift gill netting, and egg
pumping (ADF&G 1982a, 1982e). Egg pumping occurred after
fish spawning activity terminated.
Adult chinook, chum, and coho salmon were fitted with inter-
nal radio transmitters at Talkeetna and Curry in 1981 and
E-3-8
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2.1 -Overview of Resources
(b)
1982. These fish were followed to evaluate directional
movements, upstream migration rates, upstream migration
extent, and spawning locations.
Stationary gi 11 nets were ope rated near De vi 1 Canyon at
RM 150.2 at five-day intervals from late July to mid-
September 1981 and 1982 to detect adult sockeye, chum, pink,
and coho salmon.
The migration timing, upstream migration extent, and pro-
bable spawning areas of eulachon in the Sustina River were
evaluated from mid-May through mid-June 1982 by a variety of
techniques. Upstream migration timing was assessed by sta-
tionary gill nets placed at selected Susitna River estuary
locations. The extent of upstream migration was determined
by dip net and el ectrofi shi ng. Eul a chon spawning habitat
·was determined directly by searching for eggs in substrate
samples and indirectly by evaluating the spawning condition
of female smelt· collected by dip net and electrofishing at
suspected spawning sites.
During 1981 and 1982 the migration timing, upstream migra-
tion extent, and spawning habitat selection of Bering cisco
in the Susitna River were investigated. A fishwheel used
for salmon investigations was maintained through late
September 1981 and 1982 to intercept cisco. Electrofishing
was used to assess the upstream migration extent and spawn-
ing habitat selection by cisco, as evidenced by spawning
condition of captured fish.
Resident and Juvenile Anadromous Fish Investigations
Fish investigations also assessed the seasonal distribution
and relative abundance of resident and juvenile anadromous
fish 1n the Susitna River downstream from Devil Canyon (RM
152). Methods include baited minnow traps, trot (i.e., set)
1 i nes, hook and 1 i ne, e 1 ect rofi shi ng, stationary and drift
gill nets, and beach sei~s. Studies commenced in November,
1980 and are continuing. Selected tributaries and tributary
confluences, sloughs, side-channel and mainstream locations
from RM 10.1 to 148.8 of the Susitna River were sampled dur-
ing the winter (November to April) and the open-water season
(May to October). Fewer sites were sampled during the win-
ter than during the open-water season because of sampling
constraints, including the short length of daylight, and ice
conditions.
Captured fish were processed
respective capture locations.
inches (200 mm) in fork length
numbered tags.
E-3-9
and returned alive to their
All resident fish exceeding 8
were tagged with individually
2.1-Overview of Resources
Lotic habitats at resident and juvenile anadromous fish
sampling sites were described at the time of sampling to
correlate seasonal fish distribution and abundance trends to
selected physical/chemical lotic habitat components. Habi-
tat variables measured included water temperature, dissolved
oxygen, conductivity, turbidity, water depth, velocity and
instream cover (ADF&G 1981c and 1982a).
Electrofishing was conducted during the 1982 open-water sea-
son along the Susitna River from Cook Inlet to Devil Canyon
(RM 152) to tag resident fish and eva 1 uate their seasona 1
distribution and movements within the Susitna River.
Individually identi fi able radio transmitters of three-to-six
months longevity were surgically implanted in adult rainbow
trout and burbot from August through early October of 1981
and 1982 at various locations along the Susitna River down-
stream from Devil Canyon (RM 152). These tags were used to
evaluate autumn and winter movements and overwintering loca-
tions. Conventional winter fish sampling techniques,
under-ice submerged gill net sets and baited tip-ups, were
used to detect non-radio-tagged burbot and rainbow trout.
A smolt trap was operated just upstream from Talkeetna at
RM 103 from mid-June through early October 1982 to measure
the out-migration of juven·ile salmonids from the reach above
Talkeetna.
Studies were conducted upstream from Dev i1 Canyon (RM 152)
to evaluate the seasonal distribution and abundance of
Arctic grayling. Eight major clear-water tributaries,
located between RM 173.9 and 226.9, were sampled monthly
from June to September during 1981 and 1982. Arctic gray-
ling exceeding 8 inches (200 mm) in fork length were tagged
with individually numbered tags. Seasonal movements and
population estimates were derived from fish recapture data.
Segments of the 1 ower one mile of the above streams were
sampled for arctic grayling during 1981, whereas the entire
reaches of six of the eight streams that would be inundated
by the Watana impoundment were sampled during 1982.
Fish were sampled by baited minnow traps, trot lines and
seine along the eight tributaries during 1981 and 1982 to
detect the presence of other resident fishes. Selected
physical/chemical lotic habitat data were collected along
these tributaries during 1981 and 1982.
E-3-10
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2.1 -Overview of Resources
2.1.3-Threatened ~hd Endangered. Sp~cies
No threatened or endangered species of fish
in Alaska. The USFWS (1982) does not list
Alaska as being threatened or endangered.
Endangered Species Act also does not 1 i st
endangered.
2.1.4-Overview of Important Species
have been identified
any fish species in
The state of Alaska
any fish species as
Fishery resources in the Susitna River comprise a major portion
of the Cook Inlet commercial salmon harvest and provide sport
fishing for residents of Anchorage and the surrounding area.
Anadromous species that form the base of commercial and non-
commercial fisheries ·include five species of Pacific salmon:
chinook, coho, chum, sockeye, and pink. Other anadromous species
include eulachon and Bering cisco.
Important resident species found in the Susitna River drainage
include arctic grayling, rainbow trout, lake trout, burbot, Dolly
Varden, and round whitefish. Scientific and common names for all
fish species identified from the Susitna .drainage are listed in
Table E.3.2.
The Susitna River is a migrational corridor, spawning area, and
juvenile rearing area for five species of salmon from its point
of discharge into Cook Inlet to Devil Canyon, where salmon are
usually prevented from moving upstream by the water velocity at
high discharge. The majority of the 1981 and 1982 Susitna River
escapement of sockeye, pink, chum, and coho salmon spawned above
the Yentna River confluence and below Curry Station. Sloughs
between Devil Canyon and Talkeetna provide spawning habitat for
pink, sockeye, and chum salmon. Juvenile chinook and coho salmon
occur throughout the river below Devil Canyon, concentrating at
slough and suitable mainstem habitat during winter and at tribu-
tary mouths during summer.
Rainbow trout and Dolly Varden were recorded at mouths of tribu-
tary streams. Rainbow trout do not occur upstream from Devil
Canyon. Arctic grayling are the dqminant species upsteam from
Devil Canyon.
2.1.5 -Contribution to Commercial and
Non-commercial Fishery
(a) Commercial
Figure E.3.7 shows the ADF&G upper Cook Inlet salmon harvest
statis.tical areas. The upper and lower Cook Inlet commer-
cial fishery harvests mixed stocks (Tables E.3.3 and E.3.4).
E-3-11
2.1-Overview of Resources
With the exception of sockeye salmon, the majority of upper
Cook Inlet Salmon production originates in the Susitna
drainage (ADF&G l982b). The long-term average annual catch
of 2.8 million fish is worth approximately $17.9 million
(ADF&G 1982b). The Susitna River is considered the most
important salmon-producing system in upper Cook Inlet; how-
ever, the quantitative contribution of the Susitna River to
the commercial fishery can only be estimated because of:
The high number of intra-drainage spawning and rearing
areas;
-The 1 ack of data on other known and suspected sal man-
producing systems in upper Cook Inlet;
-The lack of stock separation programs (except for sockeye
salmon); and
Overlap in migration timing of mixed stocks and species in
Cook Inlet harvest areas.
Therefore, the fallowing discussion of the contribution of
the Susitna River to the upper Cook Inlet fishery as influ-
enced by the above limitations is based upon:
Historical sustained harvest in upper Cook Inlet;
-Escapement data from the ADF&G Susitna River tag/recapture
studies for 1981 and 1982; and
Conversion of the 1981 · and 1982 escapement data past
Talkeetna to an estimate of catch associated with that
escapement using 1 ong-tenn average harvest to escapement
ratios presented in Friese (1975).
Further discussion of the commercial salmon harvest is con-
tained in Chapter 5. Section 3.7.l(b).
(i) Sockeye
The commercial sockeye harvest has averaged approxi-
mately 1.11 million fish annually in upper Cook
Inlet over the last 28 years (Table E.3.3). The
estimated 1981 and 1982 catches were 1.44 million
and 3.24 million, respectively. The 1982 catch was
the highest in the 29 years of record.
E-3-12
,---_--,.,
P-"·-
-
, ....
i
""" I
-
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2.1 -Overview of Resources
( i i )
( i i i )
( i v)
The estimated sockeye escapement in the reach above
Talkeetna was 4800 in 1981 and 3100 in 1982 (Table
E.3.5, Figure E.3.8). These represented 3.6 percent
and 2. 0 percent of the estimated sockeye escapement
past Sunshine Station (Figure E.3.9). These escape-
ments represent an estimated commercial catch of
14,400 in 1981 and 9300 in 1982, assuming a 3.0:1
harvest to escapement ratio (Friese 1975).
Chum
The upper Cook Inlet chum salmon catch has averaged
approximately 614,000 fish annually since 1954 (Table
E.3.3). The 1981 and 1982 estimated catches were
843,000 and 1 ,430,000, respectively. The 1982 catch
of chum salmon was also the highest for the 29 years
of record.
The 1981 and 1982 estimates of chum salmon escapement
in the reach above Ta 1 keetna were 20,800 and 49,100
(Table E.3.5., Figure E.3.8). These represented 7.9
percent and 11.4 percent of the estimated chum es-
capement past Sunshine Station (Figure E.3.9). These
escapements represent an estimated commercial catch
of 45,800 in 1981 and 108,000 in 1982, assuming a
2.2:1 harvest to escapement ratio (Friese 1975).
Coho Salmon
Since 1954, the upper Cook Inlet coho salmon commer-
cial catch has averaged approximately 230,000 fish
(Table E.3.3). The estimated 1981 and 1982 catches
were 494,000 and 777,000, respectively, with the 1982
catch the highest during the 29 years of record.
The 1981 and 1982 estimates of coho salmon escapement
in the reach above Talkeetna were 3300 and 5100
(Table E.3.5, Figure E.3.8). These represented 16.7
percent and 11.1 percent of the estimated coho es-
capement past Sunshine Station (Figure E.3.9). These
escapements represent an estimated commercia 1 catch
of 7300 in 1981 and 11,200 in 1982, assuming a 2.2:1
harvest to escapement ratio (Friese 1975).
Pink Salmon
The upper Cook Inlet annual, average, odd-year har-
vest of pink salmon since 1954 is about 124,000 with
a range of 12,500 to 554,000, while the average even-
year harvest is approximately 1,701,000 with a range
E-3-13
2.1-Overview of Resources
of 484,000 to 3,232,000 (Table E.3.3). The 1981 and
1982 catches were 128,000 and 789,000, respectively.
The 1982 catch was the third lowest even-year catch
recorded during the 29 years of record.
The estimates of pink salmon escapement in the reach
above Talkeetna were about 2300 in 1981 and 73,000 in
1982 (Table E.3.5, Figure E.3.8). These represented
4.6 percent and 16.5 percent of the pink escapement
past Sunshine Station {Figure E.3.9). These escape-
ments represented an estimated conmerci a 1 catch of
8700 in 1981 and 278,000 in 1982, assuming a 3.8.1
harvest to escapement ratio (Feiese 1975).
(v) Chinook
Since 1954, the commercial catch of Chinook salmon in
upper Cook Inlet has averaged 19,500 (Table E.3.3).
T~e upper Cook Inlet· harvests for 1981 and 1982 were
11,500 and 20,600, respectively. Since 1964, the
opening date of the commercial fishery has been June
25, and the Susitna River chinook salmon run begins
in 1 ate 1"1ay and peaks in mid-June. Thus, the major-
; ty of chi nook have already passed through the area
subject to commercial fishing. Estimates of chinook
salmon escapement in the reach above Ta.l keetna were
10,900 in 1982 (Table E.3.5, Figure E.3.8). This
represented 22.0 percent of the chi nook escapement
past Sunshine Station (Figure E.3.9).
(b) Non-Commercial Fishing
(i) Sport Fishing
Recent increases in population and tourism in Alaska
have resulted in a growing demand for recreational
fishing. Recreation a 1 fishing is now considered a
significant factor in total fisheries management,
especially in Cook Inlet where colllTlerci al and non--
commercial user conflicts have developed {Mi1ls
1980). The Susitna River and its major salmon and
resident fish-producing tributary streams provide a
multi-species sport fishery easily accessible from
Anchorage and other Cook Inlet conmunities. In 1978,
the Susitna River and its primary tributaries
accounted for over 124,000 angler days of sport fish-
ing effort, about 10 percent of the total angler days
in Alaska (Mi1ls 1980). In 1981, over 102,240 angler
E-3-14
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2. 2 -Species Biology and Habitat Uti 1 i zat ion
( i i)
days were expended in the Susitna Basin~ representing
about 7 percent of the total angler days in Alaska
{Mills 1982).
The sport fish harvests for 1978 through 1981 from
the Susitna basin~ based on mailing surveys to a
sample of licenses, are shown in Table E.3.6 {Mills
1979, 1980~ 1981~ 1982).
The figures represent the sport fishing harvest
throughout the Susitna basin and represent an area
that is larger than that which could be affected by
the proposed project (see Figures E.3.4 to E.3.6 for
locations of major tributaries listed in Table
E. 3. 6) •
The 1978 and 1981 estimated catch of arctic grayling
represents about 28 and 33 percent of the estimated
harvest in south-central Alaska and the estimated
catch of rainbow trout represented about 13 and 10
percent of the entire state harvest in 1978 and 1981,
respectively. The 1978 and 1981 Susitna harvest of
pink salmon represented about 39 and 13 percent of
the total estimated harvest for south-central Alaska;
the harvest of coho represented about 18 and 10 per-
cent; and the harvest of chinook represented about 11
and 19 percent.
Subsistence Harvest
Although salmon form an important resource for many
Susitna basin residents, subsistence fishing within
the Susitna basin is an unquantified harvest. How-
ever, the Tyonek Village subsistence salmon fishery,
approximately 30 miles (50 km} southeast of the mouth
of the Susitna River, is supported primarily by
Susitna River stocks (see Chapter 5, Section
3. 7.1[d]}.
2.2 -Species Biology and Habitat Utilization
in the Susitn~ River Drainage
2.2.1-Species Biology
(a) Salmon
(i) Chinook
A generalized periodicity chart summar1z1ng signifi-
cant chinook life stages in the Susitna River up-
stream from Talkeetna is illustrated in Figure
E.3.10.
E-3-15
2.2-Species Biology and Habitat Utilization
-Upstream Migration of Returning Adults
In the Susitna River below Talkeetna, the adult
chinook salmon migration begins in late May and
ends in early to mid-July. Historically, by July
1, 90 percent or more of the escapement have
migrated past the Susitna Station (ADF&G 1972).
Sonar counters and fishwheels installed in 1981 at
stations identified in Figures E.3.4 and E.3.5 to
monitor escapements for pink, chum, sockeye, and
coho salmon provided incidental information
regarding the timing of chinook runs. Fishwheel
catches indicate that the 1981 migration ended by
July 7 at the Yentna Station (AOF&G 1983). Initial
sonar counts made at Sunshine Station also sugges-
ted that a significant segment of the 1981 escape-
ment had migrated past this 1 ocation prior to the
June 23 sonar counter installation.
Similarly, a sizable portion of escapement had
already passed the Talkeetna site before June 23,
when the sonar counters became operational. Fish-
wheel catches and sonar counter data indicated that
the migration had passed Sunshine Station by
July 7 (ADF&G 1983). At Curry Station, the fish-
wheels clearly defined the beginning of the 1981
migration on June 16, the peak of migration on
June 23, and the end of migration on July 4.
In 1982, the chinook migration at Sunshine Station
began, reached a midpoint and ended June 18,
June 30, and July 9, respectively (ADF&G 1983). At
Talkeetna Station the 1982 chinook migration
covered the period June 11 to August 5 with over 80
percent of the run passing Talkeetna from June 21
to July 12. A similar pattern was observed at
Curry Station where 80 percent of the fishwheel
captures were recorded from June 21 to July 12
(ADF&G 1982e). Catches at Sunshine, Talkeetna and
Curry Stations peaked on June 30, July 3, and
July 1, respectively.
Radio telemetry studies during June, July, and
August of 1981 (ADF&G l98lb) indicated that the
confluence of the Talkeetna, Chulitna, and Susitna
rivers is a milling area for migrating adult
chinook salmon. The four fish tagged at the
Talkeetna site moved downstream and remained either
at the confluence or downstream from this area for
several days or weeks before moving back upstream.
E-3-16
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2.2-Species Biology and Habitat Utilization
This downstream movement was seen in 2 of the 12
fish that were radio tagged at the Curry site. Ten
of the 12 fish tagged at the Curry Station site and
three and four fish tagged at the Talkeetna site
moved upstream, 11 entering one tributary and two
into another. Of the three remaining fish, one
moved downstream and held near Chase Creek, and two
were lost because of technical difficulties with
the transmitters.
-Population Estimates
Population estimates for chi nook were calculated
from tag/recapture data in 1982. Based on these
estimates, 49,600 chinook reached Sunshine Station,
10~900 reached Talkeetna, and 11,300 reached Curry
(ADF&G 1983; Table E.3.5).
Age Composition
In 1981, four-year old individuals were dominant at
Sunshine and Curry Stations, while at Talkeetna,
six-and four-year olds were equally abundant.
There was a higher percentage of younger fish,
mainly three-year olds, at Sunshine Station than at
either the Ta 1 keetna or Curry Stations. Seven-year
old fish were relatively scarce at Sunshine and
Talkeetna, and none were identified from the Curry
Station sample.
-Spawning Locations
Surveys of chinook salmon spawning areas were per-
formed by helicopter; single-engine, fixed-wing
aircraft; and by foot during the 1981 and 1982
investigations. Chinook appear to spawn in the
tributaries rather than the mainstem of the Susitna
River. Some of the more important spawning tri bu-
tari es include Alexander Creek, Kroto Creek,
(Deshka River), Willow Creek, Clear Creek (in the
Talkeetna drainage), Chulitna River, Peters Creek,
Lake Creek, Talachulitna River, Prairie Creek,
Montana Creek, Indian River, and Portage Creek
(Tables E.3.7 and E.3.8, Figures E.3.4 to E.3.6).
During 1982, adult chinook entered Devil Canyon and
spawned at Cheechako Creek (RM 152.5) and an
unnamed creek (RM 156.8). Peak spawning ground
counts were 16 and 4 chinook at Cheechako Creek and
the unnamed creek, respectively (ADF&G 1982e).
E-3-17
2.2-Species Biology and Habitat Utilization
-Incubation and Emergence
In the Susitna River system, chinook spawn in July
and early August (ADF&G 1981b). In Alaska, each
female deposits from 4200 to 13,000 eggs, which
incubate in the gravel through winter and hatch the
following spring (Morrow 1980). The alevins gen-
erally remain in the redd until the yolk sac is
absorbed and then emerge from the gravel and become
free-swimming, feeding fry (Morrow 1980).
-Juvenile Behavior
The chi nook fry school after emerging from the
gravel but become territorial as they grow.
Aquatic insect larvae, including chironomids and
caddis flies as well as small crustaceans, are the
major food sources for juvenile chinook salmon
{ADF&G 1978). Analysis of adult chinook salmon
scales shows that most Susitna River salmon remain
in freshwater for one year before smelting (ADF&G
1981b).
Juvenile chi nook salmon were captured throughout
the study area from Alexander Creek (RM 10.1) up-
stream to Portage Creek (RM 148.8). Collection
techniques and data summaries for juvenile collec-
tions are detailed in ADF&G (1981d). Populations
varied in abundance and distribution by river habi-
tat type and seasonal period.
During winter, most juveniles were captured at
mainstem and slough sites. All juvenile chinook
salmon captured at the mainstem and slough sites
are believed to have migrated from associated
streams, since no chinook salmon spawning has been
recorded in the mainstem or sloughs. The migration
to mainstem and slough sites during late fall is
apparently the result of icing and lowered flow in
tributaries (ADF&G 198ld).
During summer, juvenile chinook were also captured
throughout the study area bel ow Devil Canyon from
Portage Creek to Alexander Creek. The reach be-
tween De vi 1 Canyon and Ta 1 keetna accounted for 34
percent of the total captures, and the remainder
were captured between Talkeetna and Cook Inlet
(ADF&G 1981b). Tributary mouths appear to provide
important rearing habitat during summer months.
E-3-18
F------,
-
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2.2-Species Biology and Habitat Utilization
Clear-water sloughs supply summer rearing habitat
and may be important year-round rearing habitat.
During the 1981 field program, two age groups of
juvenile chinook salmon, representing brood years
1979 (1+} and 1980 (0+), were identified from scale
analysis and length distribution. Age 1+ were
observed between Devil Canyon and Talkeetna at 45
percent of sites surveyed during the first two
weeks of June. Captures decreased and terminated
in July. Age 1+ were not captured after August in
the Talkeetna to Cook Inlet reach. It was con-
cluded that the decreasing numbers of age 1+
chinook salmon were a result of smol t out-migration
(ADF&G 1981d). The highest catches of juvenile
chinook in 1982 smolt trap samples from Talkeetna
Station was recorded between mid-June and mid-July,
but the trap may have been deployed after the peak
of out-migration (Table E.3.8).
Catches of age 0+ in mainstem and slough habitats
increased from late June to a high in early
September for the Devil Canyon to Talkeetna reach.
This was interpreted as an indication that juvenile
d i stri buti on expanded from tributary streams and
stream mouth sites into mainstem and slough sites
as summer progressed (ADF&G 1981d).
Interpretation of present and past surveys of the
Susitna River and its tributaries have resulted in
the following conclusions relating to abundance,
distribution, and out-migration (ADF&G 1981d) •
• Juvenile chinook salmon populations are not
static but vary in abundance and distribution by
season within the various river habitats;
• Redistribution of juvenile chinook from areas of
emergence (tributaries) to more favorable habitat
at the mouths of·tributaries and sloughs begins
as the fish reach a mobile state;
• Tributary mouths appear to provide important
milling and rearing areas for juveniles during
summer months; •
• During late fall, tributary discharge decreases
causing the juveniles to move into the mainstem
and slough habitats to overwinter; and
E-3-19
2.2-Species Biology and Habitat Utilization
• The majority of juvenile chinook spend one winter
in freshwater before migrating to the sea. Out-
migration in the reach from Devil Canyon to
Ta 1 keetna peaks prior to early June and termi-
nates by the end of July throughout the drain-
age.
(i i) Sockeye
A generalized periodicity chart summar1z1ng signifi-
cant sockeye life history stages in the Susitna River
upstream from Talkeetna is illustrated in Figure
E.3.10.
-Upstream Migration of Returning Adults
The escapement, migrational timing, and population
estimates of adult sockeye moving up the Susitna
River to spawning grounds were measured in 1981 and
1982 by side-scan sonar, fishwheel catches, and
tag/recapture studies. The five escapement moni-
toring stations were established in early June 1981
at locations identified in Figure E.3.4 to E.3.6.
Operating dates, equipment used, and methodology
are described in detail in ADF&G (198lb); results
are reported in ADF&G (1983) •
• At Susitna Station, the 1981 sockeye salmon mi-
gration extended from July 4 to July 31 (ADF&G
1983). Because July 10 and July 23, 75 percent
of the escapement passed Susitna Station. Fish-
wheel catch per hour indicated that the peak
migration occurred between July 10 and July 19.
In 1982, the migration began, reached midpoint
and ended July 18, July 25, and August 5, respec-
tively (ADF&G 1983).
At the Yentna Station, the migration began on
July 10, and the run ended by July 30. Between
July 12 and 23, 75 percent of the total fish
escapement had passed Yentna Station. Fi shwheel
catches indicated that the migration peak was
between July 13 and 15. In 1982, the majority of
the migration passed Yenta Station between July
18 and August 6 (Figure E.3.11) •
• At Sunshine Station, the 1981 migration began on
approximately July 16, and ended on August 26.
Between July 19 and 28, 75 percent of the sockeye
E-3-20
-
-
-
-
-I
2.2-Species Biology and Habitat Utilization
migrated past this location. Based upon fish-
wheel catch records, the peak of the migration
occurred between July 18 and 23. The majority of
the 1982 sockeye migration passed Sunshine
Station between July 27 and August 18 (Figure
E.3.11).
• At Talkeetna Station, the 1981 migration com-
menced on July 23 and was completed by August 26.
A majority of the total count was made between
July 23 and August 6. It appeared from fishwheel
catch data that the migratio~ peak occurred
between July 27 and August 1. The majority of
the 1982 migration passed Talkeetna Station
between July 27 and August 18 •
• At Curry Station, the 1981 migration commenced on
July 23, was over on August 22. In 1982, the
majority of the sockeye were counted between
July 27 and August 28 (ADF&G 1983).
From the sonar data, the 1981 migration chrono-
logy of sockeye salmon indicates that those fish
passing Sus itna Station en route to the Yentna
River made the 6.2-mile (10-km) trip in one day
or less. Individuals migrating past Susitna
Station toward Sunshine Station covered this
distance in 1981 in an average of 8 days (6.8
miles per day, or 11 km per day), and reached
Talkeetna Station in an average time of 13 days
( 4. 6 miles per day, or 7. 7 km per day). Tag/
recapture data indicated that the mean travel
rate between Sunshine and Talkeetna Stations and
Curry Station in 1981 was between 3.0 and 4.4
miles per day (5.0 and 7.7 km per day) (Table
E.3.10). In 1982, the mean travel rate was
between 2.7 and 3.4 miles per day (4.5 and 5.7 km
per day).
Population Estimates
Population estimates were calculated based upon
tagging operations at Sunshine, Talkeetna, and
Curry Stations and upon side-scan sonar counts at
Yentna Station. Sockeye estimates indicated that
approximately 139,000 sockeye migrated past Yentna
Station, 133,000 migrated past Sunshine, 4800 past
Talkeetna, and 2800 past Curry Station in 1981. In
1982 the values were 114,000, 151,000, 3100, and
E-3-21
2.2-Species Biology and Habitat Utilization
1300 past the same stations, respectively (Table
E. 3. 5). The 95 percent confidence 1 imits on the
Petersen population estimates and components used
to calculate them are discussed in ADF&G (1981b,
1983).
The Susitna River drainage escapement can be
approximated by the summation of Yentna River and
Sunshine Station escapement estimates. The result
is an underestimate, however, because the escape-
ment estimates do not include escapements to other
tributaries downstream from RM 77. Using these
estimates, the minimum sockeye escapement to the
Susitna River was 272,000 in 1981 and 265,000 in
1982 (ADF&G 1983).
-Age Composition
Sockeye salmon age composition analyses in 1981
indicate that a majority of the fish sampled at
each station were age 52, (i.e. five years old
with two years in freshwater). The second most
abundant age group was 4 2 followed by age 6 2 •
Five-year-old fish comprised approximately 86 per-
cent of the return at Susitna and Yentna Stations,
73 percent at Sunshine and Talkeetna Stations, and
70 percent at Curry Station (ADF&G 1981a). Further
age composition data are given in Table E.3.11.
-Spawning Locations
Surveys of sockeye spawning areas in 1981 and 1982
were conducted in the mainstem Susitna River be-
tween Devil Canyon and Cook Inlet from 1 ate July
through September using drift gill nets, electro-
shocking equipment, and egg deposition pumps.
Susitna River tributary streams and sloughs between
Devil Canyon and the Talkeetna River confluence
were surveyed on foot for spawning salmon from late
July through September. The detailed methodology
used is given in ADF&G (1981b and 1983). No main-
stem spawning was observed for sockeye salmon. In
the Devil Canyon to Talkeetna reach, adult sockeye
were observed in 12 of the 33 sloughs surveyed and
in Lower McKenzie Creek in 1981; while in 1982,
spawning sockeye were observed in 10 of 34 sloughs
and Portage Creek (Figures E. 3.12 -E. 3.17). Peak
spawning occurred during the 1 ast week of August
E-3-22
r
2.2 -Species Biology and Habitat Utilization
and the first three weeks of September. Of the
locations listed, sockeye were most numerous in
Sloughs SA, 9B, 11, and 21.
-Utilization of Spawning Habitat
The weekly counts of spawning sockeye obtained by
ADF&G in 19S1 and 19S2 for the sloughs upstream
from Talkeetna (ADF&G 19S1a and 19S3) were
converted to estimates of the total number of
spawning sockeye in each slough. The counts were
converted to estimated total numbers using the
estimating technique described in Bell (19SO),
i.e., the counts are plotted by day, the area under
the resulting curve is calculated and divided by
the estimated average stream life of the spawning
fish. The sockeye stream life was assumed to be 12
days, based on estimates derived for the
Chakachamna system on the west side of Cook Inlet
(Bechtel Civil and Minerals, Inc. 19S3). The
estimated numbers of spawning sockeye using each
s 1 ough in 19S1 and 19S2 are presented in Tab 1 e
E. 3. 12. The tot a 1 number of sockeye estimated to
have spawned in sloughs during 19S1 and 19S2 was
2315 and 1402.
The 19S1 and 19S2 total estimates for slough spawn-
; ng sockeye are S3 and lOS percent of the Peteren
population estimates of sockeye passing the Curry
fi shwhee 1 station in the respective years. These
high percentages, combined with the lack of spawn-
ing sockeye in mainstem and tributary spawning
areas, indicate that sockeye spawning is confined
to sloughs upstream from Talkeetna. Over 9S
percent of the sockeye spawning in sloughs in 19S1
and 19S2 spawned in 11 sloughs: SA, SB, SC, Moose,
B, 9, 9A, 96, 11, 17, and 21 (Figures E.3.12 to
E.3.17; Table E.3.12). If it is assumed that there
was a 1:1.3 ratio to female sex ratio in 19S1 and
1.5:1 ratio in 19S2 (ADF&G 19S3) and that sockeye
require 72 square feet of spawning habitat per redd
(Foerster 196S, Bell 19SO), then the 19S1 spawning
sockeye used 2.2 acres {0.9 ha) and 19S2 spawning
sockeye used 0.9 acres {0.4 ha) of slough spawning
habitat. ·
Scale patterns of sockeye returning to Chulitna and
Talkeetna River spawning areas and of sockeye
spawning in sloughs upstream from Talkeetna were
examined as part of the ADF&G stock separation
E-3-23
2.2-Species Biology and Habitat Utilization
program. The analysis indicated that the sockeye
spawning in sloughs upstream from Talkeetna in 1982
were not a separate stock, but were strays from
Chulitna River and Talkeetna River stocks.
Incubation and Emergence
Based upon information from other sockeye-producing
spawning areas, mature females typically produce
from 2500 to 4300 eggs (Morrow 1980). Hatching
normally occurs during the period January-March.
Fry remain in the gravel until emerging from April
through June. In most systems, fry move into lakes
or other rearing areas after emerging from the
gravel and spend 1 to 3 years in freshwater before
migrating to feeding grounds in the Pacific Ocean
(Morrow 1980). In the Devil Canyon to Talkeetna
reach, however, there are no lakes for sockeye
rearing, and sockeye fry originating in the sloughs
appear to leave this reach during the first summer
{Table E.3.9) (ADF&G 1981d, 1982f).
-Juvenile Behavior
Results of the 1982 smolt trapping program indi-
cate that age -0 sockeye leave the Devil Canyon to
Talkeetna reach in June and July (Table E.3.9).
The peak of out-migration appears to occur in the
first two weeks of July. There was a gradual
decline in catch rate from August through
September.
{iii) Coho
A generalized periodicity chart summar1z1ng signifi-
cant coho 1 ife history stages in the Susitna River
upsteam from Talkeetna is illustrated in Figure
E. 3.10.
-Upstream Migration of Returning Adults
The escapement, migrational timing, and population
estimates of adult coho salmon migrating up the
Sus itna River to spawning grounds were determined
from results of apportioned, side-scan sonar
counts, fishwheel catches, and tag/recapture esti-
mates (ADF&G 1981b and 1983).
E-3-24
-
-
-
2.2-Species Biology and Habitat Utilization
The peak of the coho salmon migration into the
Susitna River drainage occurs in mid-July and early
August, but can extend from 1 ate June into
September. Migration periods for each sampling
station are summarized below.
At the Susitna Station in 1981, the migration
began on July 23 and ended August 9. Approxi-
mately 75 percent of the fish passed this station
between July 23 and August 16. Fishwheel catches
indicated a migration peak occurring between
July 25 and July 30. During 1982, the majority
of the run passed Susitna Station between July 19
and August 9 (Figure E.3.19) •
• At the Yentna Station in 1981, the migration
began on July 22 and ended on August 17. The
major portion of the run passed this location
between July 23 and August 16. The peak of
migration occurred between July 23 and August 6.
During the 1982 migration, the majority of the
coho passed Yentna Station between July 20 and
August 24.
• At the Sunshine Station, the beginning of the
1981 migration was August 1, and the run ended on
August 3. Between August 4 and August 24, 75
percent of the migration run occurred. The peak
migration period was between August 18 and August
25. In 1982, the majority of the coho passed
Sunshine Station between August 3 and August 23
( Fi gu re E • 3. 19) •
• At the Talkeetna, the beginning of the 1981
migration was August 6, and September 1 was the
termination. The majority of coho were counted
between August 11 and September 1. The mi gra-
tional peak period occurred between August 19 and
August 30. In 1982, the coho passed Talkeetna
Station primarily between August 5 and
September 2 •
• Curry Station fishwheel catches indicated that
the 1981 coho migration began at this location on
August 5 and ended on September 4. During 1982,
the Curry fishwheels caught coho from August 2 to
September 11 (ADF&G 1982e).
E-3-25
2.2 -Species Biology and Habitat Utilization
In 1981, the average travel time for coho salmon
migrating between Susitna Station and Yentna
Station was two days, a travel rate of approximate-
ly 3.1 miles (5 km) per day. In 1981, coho had a
migration rate of 3.9 miles (6.5 km) per day from
Susitna Station to Sunshine Station and 4.0 miles
(7 km) per day between Sunshine and Talkeetna
Stations. In 1982, the mean rate between Sunshine
and Talkeetna was 5.3 miles {8.5 km) per day.
Tag/recapture of marked coho indicated that between
Talkeetna and Curry Stations the mean travel rate
in 1981 was approximately 11.3 miles (18.8 km) per
day, while in 1982 the mean rate was 10.0 miles (16
km) per day (Table E.3.10) (ADF&G 1983).
-Population Estimates
Population estimates derived from tagging and re-
capture operations at Sunshine Station, Talkeetna,
and Curry stations and sonar counts at Yentna
Station indicated that approximately 17,000 coho
migrated past Yentna Station, 19,800 migrated past
Sunshine Station, 3300 past Talkeetna Station and
1100 past Curry Station in 1981, while 34,100,
45,700, 5100, and 2400 passed the same stations in
1982 (Table E.3.5).
The Susitna River drainage estimated escapement of
coho, derived by summing the Yentna Station and
Sunshine Station estimates, was 36,000 in 1981 and
79,800 in 1982. This estimate does not include
coho migrating to tributaries downstream from RM
77, except for the Yentna River (ADF&G 1983).
-Age Composition
The majority of individuals sampled for age
analyses in 1981 were 42 from the 1977 brood
year, followed by· age 32 from the 1978 brood
year. Less than 10 percent of the 1981 coho es.:..
capement consisted of other age groups (ADF&G
1981a).
-Spawning Locations
Surveys of spawning areas were conducted in the
mainstem, sloughs, and tributaries of the Susitna
E-3-26
,....
-
-
-
....
'
2.2 -Species Biology and Habitat Utilization
River (ADF&G 1981b}. Of 12 mainstem spawning sites
identified in 1981, coho salmon were the only
species observed at 1 site, and at 2 other mainstem
sites coho and chum salmon shared the spawning
sites. In 1982, 4 of 11 mainstem spawning sites
between Devil Canyon and Talkeetna contained coho,
and all 4 were shared with chum salmon (Table
E.3.13}. Coho salmon were not observed spawning in
any sloughs during 1981. In 1982, coho were ob-
served in 3 sloughs but actually spawned in only 1,
Slough 8A (Figures E.3.12 to E.3.17, ADF&G 1983}.
Spawning coho were observed in 8 of 15 creeks sur-
veyed between Devil Canyon and T~lkeetna in 1981
and 12 of 19 creeks surveyed in 1982 (ADF&G 1981a,
1982e). The survey data indicate that the spawning
peak occurred in the second and third weeks of
September.
-Incubation and Emergence
Based upon information on coho salmon life history
in Alaska (Hartman 1971), each female deposits an
average of 3500 eggs, which incubate in the gravel
through winter. Upon emergence in March and April,
fry generally occupy areas with adequate cover,
1 ow-water velocities, and moderate water tempera-
ture for optimum growth (Gray et al. 1978; Delaney
and Wadman 1979; Watsjold and Engel 1978). Drift-
ing aquatic insect larvae are the major diet items
of juvenile coho salmon in spring; adult stages of
these insects are major feed i terns during summer
and fall (ADF&G 1978). Juvenile pink, chum, and
sockeye salmon can also be an important supple-
mental food source to age 1 or older coho salmon
(Roos 1960; Scott and Crossman 1973}.
-Juvenile Behavior
The geographical and seasonal distribution, rela-
tive abundance, age composition, and smolt migra-
tion timing of coho salmon reared in the Susitna
drainage are summarized below based on studies by
ADF&G (1981d}.
Juvenile coho salmon were captured throughout the
study area between Alexander Creek (RM 10.1) and
Slough 21 (RM 141.8) at 55 of the 99 sample sites
sampled between November 1980 and October 1981.
Collection techniques and data summaries for juve-
nile collections are detailed in ADF&G {1981d}.
E-3-27
2.2 -Species Biology and Habitat Utilization
During the winter and spring (November-May), juve-
nile coho salmon most frequently occurred at tribu-
tary mouth sites between Talkeetna and Cook Inlet,
and at mainstem and slough sites between Devil
Canyon and Talkeetna (Table E.3.13). During June-
September 1981, j uveni 1 e coho salmon occurred most
frequently at tributary mouths in the Talkeetna to
Cook Inlet reach (Table E.3.14).
During June-September 1981, juvenile coho salmon
occurred most frequently at tributary mouths in the
Talkeetna to Cook Inlet reach (Table E.3.15}.
Three age groups of juvenile coho salmon as indi-
cated by 1 ength frequency and sea 1 e ana 1 ys is were
collected at various habitat locations in the Devil
Canyon to Cook Inlet reaches of the Susitna River
from November 1980 to October 1981. These fish
represented brood years 1978 (2+}, 1979 (1+), and
1980 (0+). Distribution of 0+ fish progressively
increased from June when they were first captured,
through September. Occurrence was consistently
higher at tributary mouth locations than at main-
stem or slough locations throughout the summer.
The frequency of occurrence in tributary mouths
increased during the summer i nd i cat i ng that age 0
coho were moving out of the tributaries. The inci-
dence of 1+ coho salmon in catches of all habitat
locations between Devil Canyon and Talkeetna also
increased from 1 ate July to September. Between
Talkeetna and Cook Inlet, a similar pattern was
observed. Catch rates then decreased in late
September for 0+ and 1+ throughout the Devil Canyon
to Cook Inlet reach (ADF&G 198lb).
Age 2+ individuals were captured during the winter
sampling period, November 1980 to May 1981, but
were not captured after May in the Devil Canyon to
Talkeetna reach and after mid-June in the Talkeetna
to Cook Inlet reach. This finding indicates that
the predominate age group for smolts in the Susitna
River is age 2+ and that in the De vi 1 Canyon to
Talkeetna reach the majority of smolting took place
prior to June 1, 1981 and between Talkeetna to
Cook In 1 et by June 15. The 1982 smo lt trapping
program at Talkeetna further supports this finding.
Peak catches of juvenile coho were recorded shortly
after the trap was set in mid-June, and catches
declined rapidly thereafter (Table E.3.9). If the
peak outmigration occurred in early June, the trap-
ping program caught the end of the migration.
E-3-28
!"""
!
,....
I
-
-
-I
.....
i
-
2.2 -Species Biology and Habitat Utilization
( i v) Chum
A generalized periodicity chart summar1z1ng signifi~
cant chum 1 i fe hi story stages in the Susitna River
upstream from Talkeetna is illustrated in Figure
E.3.10.
-Upstream Migration of Returning Adults
The escapement, migrational timing, and population
estimates of adult chum salmon migrating up the
Susitna River to spawning grounds were measured by
side-scan sonar and fi shwheel catches in combi na-
tion with tag/recapture estimates (ADF&G 1983).
Apportioned sonar counts and fishwheel catches show
that the chum salmon migration began during the
second week in July and ended during early Septem-
ber. The peak migration period in the Susitna
River upstream from Talkeetna was from late July
until late August •
• At Susitna Station, the 1981 migration began on
July 10 and ended on August 25. Between July 15
and August 7, 75 percent of the escapement
occurred. Fi shwheel catches indicated that the
migration peak occurred between August 3 and 7.
In 1982, the majority of the chum migration
passed Susitna Stat ion between July 19 and
August 10.
The 1981 migration began at Yentna Station on
July 18, and ended on August 21. A majority of
the fish were counted between July 18 and August
15. Fishwheels operated at Yentna Station indi-
cated that the migration run reached its peak
July 23. In 1982, the majority of the run passed
Yentna Station between July 20 and August 18
{Figure E.3.18) •
At the Sunshine Station the 1981 migration com-
menced on July 26, and ended on approximately
August 5. Seventy-five percent of the fish were
counted between July 27 and August 24. The peak
of chum migration at Sunshine Station, as indi-
cated by fi shwhee 1 catches, occur red on
August 19. In 1982, the chum migration passed
Sunshine Station primarily between July 29 and
August 21.
E-3-29
2.2 -Species Biology and Habitat Utilization
• At Talkeetna Station, the beginning of the 1981
migration was approximately July 28, and the mi-
gration ended on September 4. In 1982, the chum
migration passed Talkeetna Station between
August 2 and August 22 (Figure E.3.18) •
• Fishwheel catches at Curry Station indicated that
the chum migration began around August 5, and the
migration terminated on September 2. In 1982,
the majority of the chum were caught between
August 3 and August 26 (ADF&G 1983).
In 1981, chum salmon averaged 4 days travel time
between Susitna Station and Yentna Station, which
corresponds to a travel rate of 1.6 miles
(2. 7 km) per day. Average travel time between
Susitna Station and Sunshine Station was 10 days,
a travel rate of 5.6 miles (9.3 km) per day. The
migration period between Susitna Station and
Talkeetna Station averaged 14 days or approxi-
mately 5.6 miles (9 .3 km) per day. Chum salmon
tagged at Sunshine Station in 1981 took between 2
and 9 days to reach Ta-lkeetna Station, with a
mean travel rate of 4.6 miles (7.7 km) per day
(Table E.3.10). Between Talkeetna Station and
Curry Station the number of travel days in 1981
ranged from 1 to 24 days with a mean travel rate
of approximately 3.8 miles (6.3 km) per day. In
1982, the mean travel rate of tagged chum was 7.4
miles (12.3 km) per day between Sunshine and
Talkeetna and 6.5 miles (10.9 km) per day between
Talkeetna and Curry (Table E.3.10) (AOF&G 1983).
-Population Estimates
Population estimates derived from tag and recapture
data at Sunshine, Talkeetna, and Curry Stations and
sonar counts at Yentna Station indicated that
approximately 19,800 chum migrated past Yentna
Station, 263,000 migrated past Sunshine, 20,800
passed Talkeetna Station and 13,100 past Curry Sta-
tion in 1981, while 27,800, 430,000, 49,100, and
29,400 passed the same stations in 1982 (Table
E.3.5).
The Susitna River drainage estimated escapement of
chum, derived by summing the Yentna Station and
Sunshine Station estimates, was 283,000 in 1981 and
458,000 in 1982. This estimate does not inc 1 ude
chum migrating to tributaries downstream from RM
77, except for the Yentna River (ADF&G 1983).
E-3-30
.J'i""'
i
-'
2.2-Species Biology and Habitat Utilization
-Age Composition
At each samp 1 i ng site, age 4 chum sa 1 mon from the
1977 brood year dominated the catch in 1981, com-
prising, on the average, 86 percent of the sample.
Second in abundance were age 5 fish, followed by
age 3 individuals (ADF&G 1981a).
-Spawning Locations
Spawning surveys conducted in the mainstem of the
Sus itna River from Devil Canyon to Cook In 1 et
revealed that 10 of 12 mainstem spawning locations
identified in 1981 were occupied by chum salmon,
while 10 of 11 mainstem spawning locations identi-
fied between De vi 1 Canyon and Ta 1 keetna in 1982
were utilized by chum salmon (Table E.3.13).
Spawning surveys conducted in sloughs and tribu-
taries between Devil Canyon and Talkeetna docu-
mented the presence of chum salmon in 20 of the 33
sloughs surveyed in 1981 and 17 of the 34 sloughs
surveyed in 1982 (Figures E.3.12 to E.3.17).
Spawning chum were also found within the survey
reaches of 8 of 15 tributaries surveyed in 1981 and
8 of 19 tributaries surveyed in 1982 between Devil
Canyon and Ta"lkeetna. The peak spawning activity
in the sloughs occurred during the 1 ast two weeks
of August and the first two weeks of September.
Based on the stream survey data, the peak spawning
period was approximately one week earlier in
streams than in slough spawning areas.
-Utilization of Spawning Habitat
The weekly counts of spawning chum salmon obtained
by ADF&G in 1981 and 1982 for the sloughs upstream
from Talkeetna (ADF&G 1981a and 1983) were conver-
ted to an e§timate of the total number of spawning
chum in each slough using the technique described
for sockeye· salmon. For ~hum, the stream life was
assumed to be 10 days, based on estimates derived
for the Chakachamna system (Bechtel Civil and
M·ineral s, Inc. 1983). The estimated numbers of
spawning chum using each slough in 1981 and 1982
are presented in Table E.3.12. The tntal number of
chum estimated to have spawned in sloughs upstream
from Talkeetna during 1981 and 1982 was 3526 and
3674.
E-3-31
2.2-Species Biology and Habitat Utilization
The 1981 and 1982 estimates of the total number of
chum spawning in sloughs upstream from Talkeetna
are 27 and 12 percent of the Petersen population
estimate for chum passing the Curry fishwheel
station. The remainder primarily spawned in tribu-
taries, with some also spawning in the mainstem
(Figures E.3.12 to E.3.17 and Table E.3.13). Over
97 percent of the chum spawning in sloughs in 1981
and 1982 spawned in 13 sloughs: 8, SA, 8B, 8C,
Moose, A', B, 9, 9A, 9B, 11, 17, and 21. If it is
assumed that the sex ratio was 1:1 (ADF&G 1983t and
that chum salmon need 81 square feet (7 .3 m ) of
spawning habitat per redd (Hale 1981), chum used
3.3 acres (1.3 ha) and the 1982 chum used 3.4 acres
(1.4 ha) of slough spawning habitat.
-Incubation and Emergence
Based on information from other chum salmon-produc-
ing areas in Alaska, females produce an average of
3000 eggs (Hartman 1971). Limited sampling of pre-
emergent chum fry conducted April 11, 1981 near
Gold Creek (RM 136.8) revealed that yolk sac ab-
sorption was 95 to 100 percent complete. Following
emergence, usually during April or May, chum fry
remain in the river for only a short period before
out-migrating. Limited beach seine sampling resul-
ted in the capture of 1650 chum fry on June·19,
1981 in Slough 11.
-Juvenile Behavior
In 1982, a smolt trap was utilized at Talkeetna to
evaluate the timing of downstream smolt migrations.
The trap was monitored from June 18 through October
12. Peak catches of chum fry were recorded during
the first week of sampling (Table E.3.9); thus, it
is possible that out-migration peaked prior to the
June 18 sampling effort.
(v) Pink
A generalized periodicity chart summar1z1ng pink
salmon life history stages in the Susitna River is
illustrated in Figure E.3.10.
-Upstream Migration of Returning Adults
Pink salmon have a 2-year 1 ife cycle that results
in two genetically distinct stocks occurring in
E-3-32
r,-----•,
-
r
.I
......
-
-/
.-
2.2-Species Biology and Habitat Utilization
each stream. The stocks are called "odd-" or
"even-year" on the basis of the year in which
adults spawn. In the Susitna drainage, the even
year runs are numerically dominant. The escapement
migrational timing and population estimates of pink
salmon migrating up the Susitna River to spawning
grounds was measured by side-scan sonar and
tag/recapture {ADF&G 1983) •
• At Susitna Station, the 1981 migration period
started around July 10 and the migration termi-
nated on August 21. Seventy-five percent of the
escapement passed this station between July 15
and August 3. Fishwheel catches indicated that
the migration peak occurred between July 21 and
August 3. In 1982, the majority of the pink sal-
mon passed Susitna Station between July 21 and
August 5 {Figure E.3.20) •
• At the Yentna Station the 1981 migration began on
approximately July 10 and ended on August 24.
The majority of the pink salmon passed this sta-
tion between July 21 and August 6. Fishwheel
catches indicated that the migration peak
occurred on July 30. The 1982 pink migration
primarily passed Yentna Station between July 23
and August 7 •
• The 1981 migration reached Sunshine Station on
approximately July 26, two weeks later than
Susitna Station, and was completed on August 14.
Seventy-five percent of the migration was counted
between July 28 and August 9. Fi shwheel catches
showed the migration peak to have occurred
August 1. The majority of the 1982 migration
passed Sunshin.e Station between July 29 and
August 3 (Figure E.3.20) •
• The 1981 migration period at Talkeetna Station
was similar to that at Sunshine Station: the
migration reached Talkeetna on July 29, and ended
on August 20. Seventy-five percent of the es-
capement passed Talkeetna Station between July 29
and August 10. Peak fi shwheel catches occurred
between August 1 and 10. In 1982, the majority
of the pink salmon passed Talkeetna Station
between August 12 and August 13 •
• At Curry Station, the 1981 pink migration began
on July 30 and terminated approximately August
E-3-33
2.2-Species Biology and Habitat Utilization
21. Between August 4 and 19, 75 percent of the
escapement passed Curry Station. In 1982, the
pink salmon run passed Curry Station between
August 2 and August 13 (ADF&G 1983).
The migrational rates based on sonar and fish-
wheel catch data indicate that pink salmon took
an average of three days to reach Yentna Station
from Susitna Station, a distance of approximately.
6.2 miles (10 km). This represents an average
travel speed of approximately 1.9 miles (3 km)
per day. Between Susitna Station and Sunshine
Station, the average travel time was 9 days with
a travel rate of 6.2 miles (10 km) per day.
Travel time between Sunshine and Talkeetna Sta-
tions averaged 2.6 miles (4.3 km) per day. Tag
and recapture data on pink salmon indicate that
travel time between Sunshine and Talkeetna Sta-
tion in 1981 ranged from 2 to 30 days. In 1981,
pink salmon averaged three days of travel time or
6.0 miles (9.9 km) per day between Talkeetna and
Curry Station (Table E.3.10). In 1982, the mean
travel time for tagged pink salmon was 7.4 miles
(12.3 km) per day between Sunshine and Talkeetna
and 10.0 miles (16.7 km) per day between
Talkeetna and Curry (Table E.3.10) (ADF&G 1983).
-Population Estimates
Population estimates derived from tag and recap-
ture data at Sunshine, Talkeetna, and Curry Sta-
tions and sonar counts at Yentna Station indicate
that approximately 36,100 pink salmon migrated
past Yentna Station, 49,500 pink salmon passed
Sunshine Station, 2,300 passed Talkeetna Station,
and 1,000 passed Curry Station in 1981, while
447,000, 443,000, 73,000, and 59,000 passed the
same stations in 1982 (Table E.3.5).
The Susitna River drainage estimated escapement
of pink salmon, derived by summing the Yentna
Station and Sunshine Station estimates, was
85,600 in 1981 and 890,000 in 1982. This esti-
mate does not include pink salmon migrating to
tributaries downstream from RM 77, except for the
Yentna River (ADF&G 1983).
-Spawnihg Locations
Spawning surveys revealed that few pink salmon
spawn in mainstem habitats. During 1981, no
E-3-34
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2.2 -Species Biology and Habitat Utilization
mainstem spawning areas were found, while in 1982
two mai nstem spawning areas were found betwe.en
Devil Canyon and Talkeetna (Table E.3.12). In
1981, 3 of the 33 surveyed sloughs contained
spawning pink salmon while in 1982, 10 of 34 sur-
veyed sloughs between Devil Canyon and Talkeetna
supported spawning pink salmon (Figures E.3.12 to
E.3.17, ADF&G 1983). Most pink salmon spawned in
tributary habitats, with 9 of the 15 tributaries
surveyed in 1981 and 14 of 19 tributaries sur-
veyed in 1982 containing spawning pink salmon
( ADF &G 1981a, 1982e) •
-Utilization of Spawning Habitat
The weekly counts of spawning pink sal man obtai ned
by ADF&G in 1981 and 1982 for the sloughs upstream
from Talkeetna (ADF&G 1981a and 1983) were conver-
ted to an estimate of the total number of spring
pink salmon in each slough using the technique
described for sockeye salmon. The stream life was
assumed to be 7 days, based on estimates derived
for the Chakachamma system (Bechtel Civil and
Minerals, Inc. 1983). The estimated numbers of
spawning pinks using each slough in 1981 and 1982
are presented in Table E.3.12. The total number of
pinks estimated to have spawned in sloughs upstream
from Talkeetna during 1981 and 1982 was 28 and
735.
The 1981 and 1982 estimates of the total number of
pink salmon spawning in sloughs upstream from
Talkeetna represent 2.8 and 1.2 percent of the
Petersen population estimate for pink salmon· pas-
sing the Curry fishwheel station. Most pink salmon
were found to spawn in tributaries (Figures E.3.12
to E.3.17).
If it is assumed that the sex ratio was 1:1 and
that pink salmon need 6.3 square feet (0.6 m2) of
spawning habit at per redd (Be 11 1980) , then the
1981 spawning pinks used 90 square feet {8.1 m2)
and th7z 1982 pinks used 2313 square feet
(208.2 m ) of slough spawning habitat.
-Incubation and Emergence
Based on general information from other pink
salmon-producing areas in Alaska, female pink
E-3-35
2.2-Species Biology and Habitat Utilization
salmon produce an average of about 2000 eggs
(Bailey 1969). Eggs hatch in mid-winter about 3 to
5 months after they are spawned, but fry remain in
the gravel until April or May. Spawning and time
of fry emergence are related to temperature regimes
of the streams (Bailey 1969). Pink salmon fry are
about 1 inch (2.5 em) long when they emerge and
migrate directly to the sea. Limited information
obtained in spring 1981 for the Susitna drainage
indicates that sac fry of pink salmon appeared on
March 23 in Slough 11 and Indian River and yolk sac
absorption for pink fry was approximately 50 per-
cent on April 11 (ADF&G 1981d).
(b) Other Anadromous Species
(i) Bering Cisco
The Bering cisco is a coregonid (i.e., whitefish)
that occurs from the Beaufort Sea to Cook Inlet.
Although Bering cisco have been collected from upper
Cook Inlet and the Kni k Arm, the species was not
known to inhabit the Susitna River drainage prior to
1980-1981 ADF&G studies. Interior and western
Alaskan populations appear to contain both anadromous
and freshwater resident forms. Susitna River Bering
cisco appear to be anadromous (ADF&G 1981e).
Bering cisco were collected in the lower Susitna
River between RM 70 and RM 98.5 in 1981 and 1982,
respectively (AOF&G 1983). In 1981, the migration
began in August at Susitna Station (RM 26) and on
September 8 at Sunshine Station (RM 80). At
Sunshine, the 1981 fishwheel catches peaked on
September 21. In 1982, the migration began on August
7 at Susitna Station and on September 4 at Sunshine
Station. The 1982 fishwheel catches peaked on
September 27.
During 1981, spawning concentrations were identified
at RM 78 -79, 76 -77.5 and 75. In 1982, spawning
was confirmed at RM 76.8 -77.6 and 81.2 (ADF&G
1983). It is suspected that spawning may occur
throughout the reach between RM 30 and RM 100 (ADF&G
1981e). Spawning substrates were composed primarily
of 1-to 3-inch (2.5-to 7.5-cm) gravel. Peak spawn-
; ng occurred during the second week of October in
both 1981 and 1982 (ADF&G 1983). Susitna River
Bering cisco appear to occupy their spawning grounds
15 to 20 days. After spawning, these fish probably
rapidly migrate downstream to sea (ADF&G 1981e).
E-3-36
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2.2-Species Biology and Habitat Utilization
( i i) Eul achon
The eul achon is an anadromous member of the smelt
family that spends most of its 1 i fe in the marine en-
vironment. Adults are believed to live at moderate
ocean depths in the vicinity of the echo-scattering
layer and in close proximity to shore. In the north-
ern portion of its range, eul a chon spawn in May and
June.
During 1982, the spawning migration appeared to be
composed of two segments: an early run that started
prior to May 16 and ended about May 31, and a late
run that started about June 1 and ended about June 10
(ADF&G 1983). The second run was approximately 4.5
times larger in numbers than the first run. Eulachon
are known to utilize the Susitna River system at
least as far upstream as RM 58 in 1981 and RM 48 in
1982 (ADF &G 1982d) •
In 1982, eulachon spawned in riffle areas and off-
shore of cut banks on unconsolidated sands and gra-
vels. Spawning occurred at water temperatures be-
tween 37.4 to 49.1°F (3.0 to 9.5°C) (ADF&G 1983).
(c) Resident Species
(i) Dolly Varden Char
Dolly Varden char are an important sport fish and are
distributed throughout Alaska where the species occu-
PY aquatic habitats ranging from coastal streams to
lakes and streams located far inland. Dolly Varden
occur in Alaska in both anadromous and freshwater
resident forms. However, indications are that in the
Susitna drainage, Dolly Varden are not anadromous.
Dolly Varden reach sexual maturity at age 4 to age 7
and normally spawn in clear-water streams during the
fall.
Two Dolly Varden were taken in the Devi 1 Canyon to
Cook Inlet reaches from November, 1980 through May
1981. From June through September 1981, the catch of
Dolly Varden increased. Catches of Dolly Varden
peaked in June and late September; largest catches
per unit effort were recorded at the mouths of tribu-
tary streams. Higher catches during 1 ate June and
July coincided with peak migration periods of pink,
chum, and sockeye salmon; higher catches during
E-3-37
2.2-Species Biology and Habitat Utilization
September can be attributed to Dolly Varden moving
into their spawning areas within clear-water tribu-
taries and the beginning of out-migration into their
wintering habitat. Sexually mature fish were found
in September and October, and Dolly Varden displaying
spawning behavior were observed on October 2 in Upper
Indian River (ADF&G 1981e).
(ii) Rainbow Trout
Rainbow trout are one of the most valued sport fishes
in North America. Susitna River sport harvest and
effort levels have steadily increased over the past
five years. The general life history is discussed by
Morrow (1980) and Scott and Crossman (1975).
Low numbers of rainbow trout were collected through-
out the winter months (November-May 1981) from RM 10
to RM 133 at seven tributary and four mai nstem 1 oca-
tions. During summer (June-September 1981), rainbow
trout were captured from RM 10 to RM 148 near Portage
Creek but not in the impoundment reach. Portage
Creek represents· one of the northernmost boundaries
of the native range for rainbow trout in North
America. The most consistent catches were associated
with tributary mouths and sloughs between Devil
Canyon and Talkeetna. Age groups 2, 4, and 5 made up
a majority of the fish collected (ADF&G 1981e).
Catches peaked in 1 ate June between Devi 1 Canyon
and Talkeetna and again during the first two weeks of
September throughout the drainage. The June peak was
probably the result of the presence and movements of
spawning fish, whi 1 e the high in September probably
reflected movement downstream into winter habitat
(ADF&G 1981e).
(iii) Arctic Grayling
The arctic grayling is also one of the most important
sport fishes of Alaska and northern Canada and con-
tributes substantially to the sport fishery of the
Susitna River and its tributaries. Grayling are gen-
erally residents of clear, cold streams and lakes
(Scott and Crossman 1973).
Silt-laden glacial systems, such as the Susitna
River, are believed to support relatively few gray-
ling; however, such systems may provide essential
migratory channels and over-wintering habitat (ADF&G
E-3-38
·-
,_
I
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2.2 -Species Biology and Habitat Utilization
1981e). The arctic grayling is characterized by Reed
(1964) as a migratory species. During spring breakup
from April to June, adults migrate from ice-covered
1 akes and 1 arge rivers into clear, gravel bottomed
tributaries to spawn (Morrow 1980). In Alaska,
arctic grayling reach sexual maturity at age 2 to 7
years and are capable of spawning several times dur-
ing their lifetime. After spawning, the adults move
from the spawning areas to spend the rest of the
summer feeding on aquatic and terrestrial insects
taken from the aquatic drift (Vascotto 1970). A
downstream migration back to overwintering areas in
large rivers and deep lakes occurs in late August to
mid-September (Pearse 1974).
Ouri ng 1980-81 ADF&G studies, grayling were captured
between Alexander Creek (RM 10. 1) and the upper
reaches of the impoundment area. Catches were 1 ow
throughout winter months, but increased sharply in
May, both below and above the impoundment area.
Below the impoundment area, catches increased during
the period May 1-15 and then declined at all habitat
1 ocat ions throughout the summer until catches again
increased at tributary mouths in September. Within
th~;! impoundment area, catches were highest in June
and July and declined towards the end of summer and
early fall (Table E.3.16).
Changes in distribution and catch of grayling are
associated with migrational movements to spawning
grounds and overwintering areas that may have been
initiated in response to surface water temperature
(ADF&G 1981e). Bel ow the impoundment area, high
catches in May are associated with migration from the
mainstem Susitna into nonglacial tributary spawning
grounds. High catches in September are probably
associated with migrational movements back to over-
wintering areas in the mainstem Susitna.
Within the impoundment area in May and June, grayling
appeared to move upstream into pool-type habitat in
tributaries where they had spawned. The movement may
be associated with increasing water temperatures
(ADF&G 1982a). As surface water temperatures began
to decrease in late summer and early fall, lower num-
bers of fish were observed in these upper stream
reaches and tagged fish were observed migrating down-
stream. Sma11-scal e ·distribution patterns and abun-
dance within upper stream reaches are determined
primarily by streamflow and channel morphology.
E-3-39
2.2-Species Biology and Habitat Utilization
Observed preferred grayling habitat characterized by
high pool/riffle ratios, large, deep pools, and mode-
rate velocities (ADF&G 1982a).
Additional di stri buti on patterns in the impoundment
reach were documented by catching, tagg·i ng and re-
leasing 2511 grayling during 1981 (ADF&G 1981f).
Many tributary fish moved into the Susitna mainstem
for overwintering. Analysis indicates that there is
a wide range of intertributary migration as well as
movement within individual tributaries.
Grayling population estimates were calculated for the
reaches of major tri but aries to be inundated by the
Devil Canyon and Watana impoundments (Table E.3.17).
The 1982 estimates were based on tag/recapture data
during July and August 1982, while the 1981 estimates
were based on results from the entire summer period.
There were insufficient tag returns from Watana Creek
in 1981 and from Tsusena and Fog creeks in 1982 to
derive estimates. The 1982 population estimate was
calculated for age groups (Table E.3.18). The total
grayling population in the impoundment zone was esti-
mated to be at least 16,000 in 1982, while the popu-
lation of grayling over 8 inches (20 em) was estima-
ted to be 9375, excluding Watana Creek in 1981 (ADF&G
198lf, 1982e). In 1982, summer density estimates
ranged from 323 grayling per mile (1.6 km) in Watana
Creek to 1835 grayling per mile (1.6 km) in Deadman
Creek for the reaches to be inundated (Table
E.3.17).
There was no evidence of spawning at any sampling
locations between Devil Canyon and Cook Inlet. In
the impoundment reach grayling fry were captured at
the Watana Creek study area in 1981, indicating
spawning in the immediate vicinity. It is thought
that adult grayling from the mainstem-Susitna below
Devil Canyon migrate into nonglacial tributaries to
spawn some time in late April or May. In the im-
poundment reach, spawning may occur from 1 ate April
through early May under ice or during mid-May spring
floods in the lower reaches of all eight tributaries
sampled. Suitable spawning habitat, i.e., proper
spawning gravel in pool regions, was observed in all
streams studied (ADF&G 1982a). Assum·ing favorable
spawning conditions exist, it is not likely that
spawning habitat significantly limits grayling in the
impoundment area (ADF&G 1982a). Availability of
E-3-40
F"--~
~-,
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I
1. -
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2.2 -Species Biology and Habitat Utilization
( i v)
(v)
summer feeding areas is probably more significant in
limiting the grayling population in this area.
Lake Trout
Near the Watana impoundment area, 1 ake trout were
collected in Sally Lake and Deadman Lake. Both lakes
support a 1 imited sport fishery. Of the two 1 akes,
only Sally Lake wi 11 be inundated by the proposed
Watana impoundment. All lake trout were captured
within 130 feet (39.4 m) of the shoreline in less
than 6 feet (1.8 m) of water. A total of 35 lake
trout were captured: 32 in Sally Lake and 3 in
Deadman Lake. All Deadman Lake fish were captured by
hook and 1 ine, while gill nets produced the highest
catches in·5ally Lake. Gill nets were not used in
Deadman Lake. Age group 5 dominated the catch.
During mid-August, both pre-and post-spawning 1 ake
trout were captured in Sally Lake.
Burbot
In Alaska, burbot are distributed in the Susitna and
Copper rivers, Bristol Bay drainages, throughout the
interior, and in the Arctic (McLean and Delaney
1978). Burbot mature between ages 3 and 6 in Alaska
and may 1 i ve a total of 15 to 20 years. Spawning
generally occurs between mid-December and April in
shall ow water over a substrate of sand or gravel.
Movements and migration of burbot are not well docu-
mented. Burbot support a 1 imited sport fishery in
the Susitna River.
During winter (November 1980 through May 1981) burbot
were caught throughout the reach between Devil Canyon
and Cook Inlet. The highest catch rates were re-
corded downstream from Talkeetna, at the mouth of
Kroto Creek and Alexander Creek. Two mainstem sites
upstream from Talkeetna, one 2 miles (3 km) below
Portage Creek (RM 146.9) and one upstream from Lane
Creek (RM 114.4) produced the highest catches of
burbot in this reach (ADF&G 1981e).
During the summer of 1981, burbot catch rates for
Talkeetna to Cook Inlet reach and in the impoundment
reach upstream of Devil Canyon ·increased as summer
progressed, reaching a maximum in September. In the
De vi 1 Canyon to Ta 1 keetna reach, catches declined
from early June until mid-July, then increased
E-3-41
2.2-Species Biology and Habitat Utilization
throughout the remainder of summer. Burbot catches
during low flows were restricted to the mainstem,
deeper sloughs, and side-channels in the Devil Canyon
to TaHeetna reach. During high flows, burbot were
captured at a greater number of locations including
shallow side channels, sloughs and tributary mouths
(ADF&G 1981e).
Age groups 4, 5 and 6 made up the majority of burbot
caught in the impoundment zone and age groups 4, 5
and 8 made up the majority of burbot caught between
Devil Canyon and Cook Inlet. Population estimates
were not made in any of the reaches ( ADF&G 1981e,
1981f).
Although no observations of spawning burbot were made
during the 1980-81 season, collection of female bur-
bot in early September with well-developed eggs and
collection of spent burbot from November to May sug-
gested that lower Susitna River burbot spawn between
November and January. Both sexually ripe and unripe
mature burbot observed from June through September
indicate that nonconsecutive spawning occurs for
Susitna River burbot. Location of spawning and rear-
ing areas in the Susitna were not documented, al-
though juvenile burbot were captured at Alexander and
Kroto creeks (ADF&G 1981e).
(vi) Round Whitefish
Round whitefish are distributed across all of arctic
and interior Al asl<a. They are normally abundant in
clear-water streams with gravel-cobble substrate but
can be found in large glacial rivers and lakes.
Whitefish mature at age 4-7, and spawning occurs in
1 ate September through October over gravel substrate
in the shallows of rivers and inshore areas of lakes
(Morrow 1980). Upstream migrations are often asso-
ciated with spawning.
Round whitefish were captured at four locations (all
below Talkeetna) during the 1980-1981 winter studies.
The fish were all capturedo as they moved upstream
during March, April, and May. The presence of white-
fish near the mouths of tributary streams in the
March to May period after none had been caught in the
same locations between November-February, indicates a
general pattern of movement into the various tribu-
taries in the spring (ADF&G 1981e).
E-3-42
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r
'
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2.2-Species Biology and Habitat Utilization
During the summer, the incidence of whitefish caught
in the Devi 1 Canyon and Cook Inlet reach was hi ghe'r
than during the winter and peaked in June and
September. The most productive sites were Anderson
Creek, Sloughs 10 and 11, and Portage Creek mouth.
The most prevalent age groups were· ages 3, 4, and 5
(AOF&G 1981e). Round whitefish were also captured
upstream of Devil Canyon during the summer. Jay and
Kosina Creeks were the most productive areas for
round whitefish in the impoundment reach. Age group
7 was encountered most frequently (ADF&G 1981f).
(vii) Humpback Whitefish
In Alaska, there is a complex of three closely
related species of whitefish: humpback whitefish,
Alaska whitefish, and lake whitefish. Because of
similar appearance and overlapping distributions, the
data col1 ected on the three species have been
reported under the general f.leadin.g of humpback white-
fish. The Alaska whitefish is not recognized by
AFS/ASIH (Robins et al. 1980).
During the 1980-'81 winter, a single humpback white-
fish was captured be 1 ow the mouth of Monta,na Creek.
During the-summer of 1981, peak catchtes ·were made in
early June and 1 ate September (ADF&G 1981e). Largest
catches per unit effort were recorded at the mouth of
Anderson Creek, the mouth of Portage Creek, and a
slough at RM 23.8. Generally, humpback whitefish
were most abundant in Ute Jalkeetna to Cook Inlet
.rea:ch.. fish collected ranged from ages 2 to 7; age 4
was the predominant age group (ADF&G 1981e).
No evidence of humpback whitefish spawning was col-
1 ected at any samp 1 i ng 1 ocat ion betwee-n nevi~ 'Canyon
and Cook Inlet in 1981. Inspections of dissected
E-3-43
I
2.2-Species Biology and Habitat Utilization
fish caught from mid-September to early October
showed well developed gonads, but fish were not ready
to spawn. Because no whitefish were caught or
observed after October 7, it was specula ted that
spawning must occur after this date (ADF&G 1981e).
(viii) Longnose Sucker
The longnose sucker, the only representative of the
sucker family found in Alaska, is ubiquitous and
occurs in most of the mainland drainages. Spawning
usually occurs in spring after ice out. Spawning
runs (i.e., movement from lakes into inlet streams or
from deep pools into shallower, gravel-bottomed
stream areas) are initiated when water temperatures
exceed soc (41°F). Longnose sucker feed almost ex-
clusively on benthic invertebrates but will occasion-
ally ingest live or dead fish eggs (Scott and Cross-
man 1973).
Long nose sucker were collected throughout the study
area from Cook Inlet to the upper reaches of the im-
poundment area. No specimens were collected during
winter sampling. During the summer of 1981, adult
suckers were captured in the impoundment zone from
May-September, generally near the confluence of main-
stem river and the tributary streams (ADF&G 1981f).
Ou ring the same period, the percentage of habitat
locations where fish were collected was relatively
high in June from Devi1 Canyon to Cook Inlet with
1 ower catches recorded during July and August. The
percentage increased again during September between
Talkeetna and Cook Inlet but not between Devil Canyon
and Talkeetna. Anderson Creek, Kroto Creek, Sunshine
Creek, and the mainstem of the Susitna River (RM
40.6) were the most productive locations. The most
prevalent ages were 4, 5 and 6.
(ix) Threespine Stickleback
Threespine stickleback generally inhabit shallow
areas in bays and estuaries and in rivers not more
than a hundred miles upstream from the coast. Win-
tering areas tend to be in deeper waters. Stickle-
back feed main1y on small crustaceans and insects.
Threespine stickleback were collected throughout the
Devil Canyon to Cook In 1 et reach of the Sus itna
River. Catches per unit effort in the Lower River
E-3-44
r-·~
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2.2-Species Biology and Habitat Utilization
were higher, overall, than those in the Devil Canyon
to Talkeetna reach. The number of habitat locations
that produced threespine stickleback was highest in
June and declined steadily to September. The higher
percentage in early summer indicated that fish had
been involved in spring spawning movement. This
activity was not observed in September {ADF&G
1982a).
(x) Cottids
(xi)
All sculpin species captured in the Susitna River
have been grouped under the general heading of cot-
tids. The slimy sculpin is the most common cottid
found in the Susitna, although there is a possibility
that three other species may be present bel ow the
impoundment area.
Between November 1980 and October 1981, cottids were
captured throughout the Devil Canyon to Cook Inlet
reach of the Susitna River (ADF&G 1981e). The catch
rate in the impoundment area from May to September
was 0.11 per trap day {AOF&G 1981f). The percentage
of sampling locations producing catches in the Lower
River attained a high in late August and a low in
late July. For the Devil Canyon to Talkeetna reach,
there was a high in early July and a low in late
September. Habitats associated with clear-water
tributaries consistently produced the highest catches
throughout the study area from Cook Inlet to above
the proposed impoundment zone (ADF&G 1981e, 1981f).
Lamprey
The arctic lamprey, one of four lamprey species that
occurs in Alaska, was observed in the Susitna River
during 1981 {ADF&G 1981e). The Pacific lamprey, an
anadromous species that has been reported to range
into the lower Susitna River {Morrow 1980), was not
observed during 1981 investigations.
Some populations of arctic 1 amprey are composed of
both anadromous and freshwater forms. It was specu-
lated that a portion (30 percent) of the Susitna pop-
ulation is anadromous based on analysis of length
frequencies {ADF&G 1981e). The anadromous form is
parasitic; hosts include adult salmon, trout, white-
fish, ciscoes, suckers, burbot, and threespine stick-
leback {Heard 1966). The freshwater forms have been
reported to be both parasitic and nonparasitic.
E-3-45
2.2 -Species Biology and Habitat Utilization
Arctic lamprey spawn during the spring in streams of
low-to-moderate flow. Eggs develop into a larval
stage, which spend one to four years burrowed into
soft substance. After an i ndefi ni te period, adults
migrate upstream to spawn.
Arctic 1 amprey were captured at 14 sampling sites
between RM 10 and Rl'¥1 101 that were surveyed from
November 1980 through September 1981. During the
winter surveys, the or.ly habitat site to produce
arctic lamprey was Rustic Wilderness, where one
1 amprey was captured. All other 1 amprey were col-
1 ected during the summer months. Lamprey were not
co11 ected in the impoundment area (ADF&G 1981e}.
The highest catch frequency was recorded during the
September 1 to 15 sampling period. All lamprey taken
during this period were collected at tributary sites
downstream from RM 50. 5. The 1 owest incidence of
capture for this species during the summer was ob-
served in the July 16-31, 1981 sampling period (ADF&G
1981e).
2.2.2-Habitat Uti1ization
The physical parameters associated with the free-flowing charac-
teristics of the Susitna River determine the quality of the
aquatic habitat available to the fishery resources. Alteration
of these physical parameters wou1 d ultimately affect associated
fish populations. The complex relationship between the aquatic
habitat and the physica1 parameters that exist is compounded by
the effects of seasonal and yearly fluctuations in physical habi-
tat components.
Most of the baseline description of the Susitna River aquatic
habitat presented below is based on reports of habitat evaluation
studies conducted by ADF&G during the 1980-81 field season (ADF&G
1981c, 1982a) and by results of continuing stud.ies during the
1981-82 season. These studies have i dent ifi ed season a 1 habitat
characteristics of selected anadromous and resident species with-
; n the study area.
Species occurrence, relative abundance, and the significance of
aquatic habitat to species and important life history stages are
discussed below for each of the three defined study reaches:
Oshetna River to DeviT Canyon., Devil Canyon to Talkeetna, and
Talkeetna to Cook Inlet.
E-3-46
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2.2-Species Biology and Habitat Utilization
The gradation of habitat types available in the Susitna River
were grouped into four classes: mainstem, side channel, slough,
and tributary mouth. Each of these habitat types encompass a
range of physical attributes rather than a set of fixed
characteristics (Trihey 1982d).
-Mainstem habitat consists of that portion of the Susitna River
that conveys streamflow at all times. Both single and multiple
channe 1 reaches are included in this category. The phys i ca 1
characteristics of mainstem habitat in the Susitna River
reflect the integration of the streamflow, sediment, and ther-
mal regimes of the upstream basin with the topography and geol-
ogy of a particular river segment. Ground water and tributary
inflow are generally minor contributors to streamflow within a
river segment, although tributaries provide more than nal f of
the flow in the river downstream from Talkeetna. Total sedi-
ment 1 oad and suspended sediment concentrations ar·e dependent
upon glacial melt and rainfall or snow melt. Stream tempera-
ture responds primarily to meteorological conditions and
directly influences intergravel water temperatures.
-Side-channel habitat consists of those portions of the Susitna
River that normally convey streamflow only during the high flow
open-water season but which become appreciably dewatered during
periods of low flow. In general, shallower depths, lower
velocities, and smaller streambed materials occur in side chan-
nels than occur in the mainstem. However, the streamflow,
sediment, and thermal regimes of side-ch-annel habitats respond
directly to mai nstem conditions. Tributary and ground water
i:nfl ow may prevent side-channel habitats from becoming com-
pletely dewatered as mainstem flows receed; however,. the pres-
ence of these inflows is not considered a necessary component
to define side-channel habitat.
-Sloughs are overflow channels that convey glacial meltwater
from the mai nstem during· moderate and high-flow periods and
that convey clear water from local runoff and ground water dur-
ing intermediate and low-flow periods. Sloughs are generally
located on the downstream side of old, well-vegetated point
bars. The-streambed elevation in a slough is notably higher at
the upstream entrance than at the mouth, and sloughs often
function like small stream systems. A portion of the channel
in each slough, which may vary in 1 ength from se.veral hundred
to several thousand feet, conveys water without the influence
af the mainstem backwater.
The physical characteristics of sl ot1gh habitat appear to depend
upon the tnteraction of four-pr-ifrcipal fa,ctors:' the cHscharge
of the mainstem Susitna River, surface runoff patterns from the
adjacent catchment area, ground water flow contributions, and
E-3-47
2.2-Species Biology and Habitat Utilization
ice processes within the mai nstem river system. These four
principal factors interact to varying degrees during different
portions of the year to provide a unique habitat type.
The amount of streamflow in the mainstem of the Susitna River
influences habitat conditions in the sloughs: (1) by causing a
backwater effect at the mouth of the slough which faci 1 itates
access into the slough and (2) by overtopping the upstream end
of the slough at high flows, thereby flushing debris and fine
sediments from the slough. Local surface runoff contributes a
greater portion of the clear-water flow to the slough than the
ground water upwelling during the ice-free period of the year.
During winter months, ground water provides nearly all of the
flow in the sloughs. The ground water upwelling in the sloughs
maintains open-water conditions in the slough during the winter
season.
Spring breakup combined with high flows in the mainstem river
also maintains the character of the slough habitat by flushing
debris and beaver dams from the sloughs, which can be barriers
to upstream migrants during periods of low flow. Mainstem
river winter ice processes also contribute to the maintenance
of ground water upwelling in the sloughs during the winter
season.
-Tributary habitat consists of the full complement of habitats
that occur in the tributary streams of the Susitna River. The
streamflow, sediment, and thermal regimes reflect the integra-
tion of the hydrology, geology and climatology of the tributary
drainage. Therefore, physical characteristics of tributary
habitat are not dependent on rna i nstem river conditions that
exist at the tributary mouth. At the mouth of most tributaries
the stage of the mainstem river causes a backwater that extends
into the tributary, and the tributary flow creates a clear-
water plume along the bank in the mainstem. This interaction
provides another type of habitat (tributary mouth habitat) that
is considered a subset of tributary habitat.
(a) Oshetna River to Devil Canyon
The impoundment reach of the Susitna River flows through a
steeply cut, degrading channel. From Devil Creek (RM 162)
to the downstream end of Devi 1 Canyon (RM 150), the river
forms one channel that lies in a deep valley with an average
gradient of 31 ft/mile (5.9 m/km). From Oshetna River
(RM 233) to Devil Creek, the river is wider and often splits
into two or more. channels with an average gradient of
approximately 13 ft/mile (2.4 m/km). Substrates throughout
the impoundment reach and mouths of tributaries generally
consist of rubb 1 e, cobb 1 e, and boulders, often embedded in
sand; gravels are present in some locations (ADF&G 1981c).
E-3-48
-
r
-
2.2-Species Biology and Habitat Utilization
Because of the inaccessibility of the Devil Creek and Devil
Canyon area and the apparent lack of suitable fisheries
habitat, the study area was limited to that section of the
Susitna River from the Oshetna River to Fog Creek (RM L77)
(ADF&G 1981c). Based upon a preliminary reconnaissance of
the upper Susitna River basin (ADF&G 1977), eight major
tributaries were selected for fisheries studies: Fog and
Tsusena creeks in the proposed Devil Canyon impoundment; and
Deadman, Watana, Kosina, Jay and Goose Creeks and the
Oshetna River in the Watana impoundment. For the purpose of
this study, the first mile of each of these streams upstream
from their confluence with the Susitna River was sampled.
To assess mainstem utilization, sampling was conducted in an
area 300 feet (90 m) upstream and downstream from a tribu-
tary•s confluence with the Susitna River.
Overall values of the physiochemical parameters measured in
the mainstem during May to September (ADF&G 1982a) include:
-Well-oxygenated water (9.0-14.1 mg/1);
-pH values near seven or slightly higher (6.8-7.9);
-Moderate conductivity values (44-248 umhosjcm);
-Water surface temperatures in the range of 1. 5-12. 6°C
(34.7-54.7°F); and
Low turbidity levels in the tributaries (0.3 to 19 NTU)
compared to the mainstem (10 to 175 NTU).
(i) Mainstem Habitat Near the
Confluence of Major Tributaries
-Species Occurrence and Relative Abundance
Although adult chinook salmon were documented for
the first time at RM 156.8 in 1982, no other anad-
romous species were reported in the mainstem
Susitna in the impoundment reach (ADF&G 1982e).
This supports the current opinion that hydraulic
characteristics of the Susitna River at Devil
Canyon act as a barrier to upstream salmon movement
during high flows (ADF&G 1982a).
Seven resident species occur in the mainstem: arc-
tic grayling, longnose sucker, humpback whitefish,
round whitefish, Dolly Varden, burbot, and s 1 i my
sculpin. The longnose sucker, round whitefish, and
E-3-49
2.2-Species Biology and Habitat Utilization
burbot were almost exclusively captured in the
mainstem near the mouths of the tributaries. Based
on tagging studies, the arctic grayling occupied
mainstem locations primarily during winter.
-Significance of Habitat
The mainstem Susitna River in the impoundment reach
provides primary overwintering habitat and mi gra-
t ion routes between tr·i butari es for arctic grayling
(ADF&G 198lf).
B urbot use the ma i nstem immediate 1 y up or down-
stream from tributaries as year-round habitat. All
burbot catches in the impoundment area were made in
the mai nstem between May and September .(ADF&'G
198lf). It is unlikely that tributaries would be
utilized during winter months because of ice condi-
tions.
Round -whitefish and l ongnose suckers also use the
mai nstem near tributary confluences as year-round
habitat. However, no specific spawning or rearing
areas were identified (ADF&G 198lf) •
. (ii) Tributaries
Species Occurrence and Relative Abundance
At least two r~sident species, arctic grayling and
cottids, occur in tributaries. Other species ·cap-
tured near the mouths of tributaries, as discussed
above under Section (i), probably also use the tri-
butaries periodically; howe~er, none were captured
in the tributaries during the field studies.
Abundance estimates for grayH ng from 1982 data
indicate that in excess of 16,.300 grayling inhabit
clear-water tributaries in the impoundment zone
during the summer {Table E.3.1T). Total catch of
cottids was 38 in 352 trap days.
-Significance of Habitat
Tributaries are primarily utilized by grayling as
spawning and rearing habitat {ADF&G 1982a). Al-
though spawning has not been ,observed in the im-
poundment ;zone, suitable spawning habitat {sandy
gravel) does exist in all of the tributaries
E-3-50.
-
-
2.2 -Species Biology and Habitat Utilization
(b)
sampled, and it is likely that spawning occurs in
the lower reaches of these tributaries. Grayling
fry were found 1 n the 1 ower reaches of Watana
Creek, indicating that spawning had occurred near-
by. Grayl·ing that have completed spawning move
upstream into areas that have pool type habitats
where they remain throughout the summer. Large,
deep streams with a high pool/riffle ratio and
moderate streamflow velocity (below 2.0 ft [0.6 m]
per sec), such as the Oshetna River and Kosi na
Creek, provide optimal habitat (ADF&G 1982a).
Devil Canyon to Talkeetna
In the reach of the Su sitna River from Devi 1 Canyon to
Talkeetna, the river channel is relatively stable and
straight with some meandering and minimal braiding. Nume-
rous islands, gravel bars, and sloughs are present. Flow
alternates between a single channel and split channels con-
figuration throughout the reach. Between Curry ('R'M 120) and
Talkeetna the approximate gradient is 8.1 feet per mile
(1.5 m/krn). Typical substrate between Curry and Talkeetna
is gravel, rubble, and cobble with small amounts of sand and
silt. Above Curry the substrate varies from silt to
bedrock~ The majority of mai nstem shoreline substrate is
rubble and cobble whereas silt and gravel are the most
common substrate in sloughs and slow water areas. Below
Curry, streambank vegetation is dense spruce/hardwood
forest. In addition to numerous smaller streams draining
the surrounding hillsides, the principal tributaries to the
Susitna River in the Devil Canyon to Talkeetna reach include
Portage Creek, Indian River; Gold Creek, Fourth of July
Creek, Lane Creek, and Whiskers Creek.
A breakdow,n of the habitat study sites in the Devil Canyon
to Talkeetna reach includes 11 slough sites, 8 mainstem or
side-channel sites, and 5 tributary sites. Ranges of
physiochemical parameters measu red• for these sites from May
to September 1981 are shown in ADF&G (1982a). Ranges given
for tributary ~ites included all of the sampling sites from
t:hat particular tributary. Overall trends for physiochemi-
~al parameters measured in this reach included:
-High dissolved oxygen (8.8-12.8 mg/1);
-Moderate conductivity readings, ( 15-222 umhos/cm);
E-3-51
2.2-Species Biology and Habitat Utilization
-pH values in the range of 6.1-7.8, slightly lower than the
impoundment reach or downstream. Tributaries such as
Whiskers Creek and Indian River had slightly lower pH
values than mainstem or slough sites;
-Turbidity levels were generally lowest at upstream
tributary sites (0.4-148 NTU). levels were also generally
1 ower in downstream tributary sites and sloughs when the
influence of the mainstem Susitna was negligible. levels
were highest in the mainstem (23-230 NTU).
( i) Ma i nstem and Side Channels
The Susitna River from Devil Canyon to Talkeetna has
both single and split channel configuration reaches.
Single channel reaches are generally stable with
non-erodible banks controlled by valley walls,
bedrock or armor layer consisting of gravel/cobbles.
The channel is either straight or meandering. In
straight channel reaches, the thalweg often meanders
across the channel. Occasional fragmentary deposits
can be found in the floodplain. Split channel
configurations are characterized by moderately stable
channels with a gravel/cobble substrate. There are
usually no more than two channels in a given reach.
Channels are separated by well established vegetated
islands. The main channel behaves much like a single
channel at low flows with the side channels flowing
only at discharges above about 20,000 cfs. Bankfull
f1ow generally corresponds to the mean annual flood
(R&M 1982c).
-Species Occurrence and Relative Abundance
• Sal man
Five species of Pacific salmon were observed in
the Susitna River between Devil Canyon and
Talkeetna. Studies indicate that adult salmon
utilize the mainstem upstream from Talkeetna from
late spring into the fall during migration and
spawning periods (ADF&G 1981b). Use periods for
adults of each species are:
Chinook--mid-June through July;
Sockeye--July 23 through mid-September;
Coho-~July 30 through September;
Chum--July 28 through mid-September; and
Pink--July 27 through August.
E-3-52
~~-,
-
-I
!
,_.
I
-
2.2-Species Biology and Habitat Utilization
Relative abundance estimates based on 1981 and
1982 escapement data and population estimates are
given in Table E.3.5 for each of the salmon
species that utilize this reach of the Susitna
River primarily as a passage way to spawning
areas.
J'uvenile salmon are also present in the mainstem
at various times of the year. Periods of use and
relative abundance are outlined below.
Chinook--During winter, juveniles were most
abundant in the mai nstem. Prior to June 1
through the end of July, age 1+ juveniles were
abundant as they were observed moving
downstream in the mainstem.
Sockeye--In 1982 sockeye juveni 1 es moved out
of the Devil Canyon to Talkeetna reach as age
0 fish, primarily during June and July (Table
E.3.9).
Coho--During winter, coho are most abundant in
the mainstem. During summer they are slightly
1 ess abundant in the mai nstem than at the
tributary mouths. In 1982, out-migration
peaked in June.
Chum--The majority of the chum juveniles
migrated downstream prior to July 1 in 1982.
Pink--Studies to date have caught few pink
juveniles in the mainstem •
• Resident Species
Resident species reported in this reach included
all of the resident fish reported in the Susitna
River drainage (Table E.3.2) except for lake
trout. Resident fish observed throughout the
year in the mainstem include burbot and longnose
sucker. Other resident species were most abun-
dant in the mai nstem primarily during the 1 ate
fall, winter, and early spring.
-Significance of Habitat
Based on existing data, the mainstem Susitna River
between Devil Canyon and Talkeetna is primarily
E-3-53
2.2-Species Biology and Habitat Utilization
used by anadromous and resident species as a
mi grat i anal corridor and overwintering area. The
significance of mainstem aquatic habitat is
discussed below for various species of commercial
and recreational importance •
• Salmon
The mainstem reach from Devil Canyon to Talkeetna
serves as a migration corridor for a relatively
small percentage· of the total Susitna River
salmon escapement (Table E.3.5, Figure E.3.9).
During migration periods, various behavioral and
distribution patterns are associated with certain
characteristics of mainstem habitat, including
water depth, velocity, channel configuration, and
1 ocati on or absence of obstructions (ADF&G
1981c).
Generally, passage of adult salmon during migra-
tion corresponds with the summer high flow sea-
son. However, passage of adult salmon on a daily
basis (measured by side-scan sonar) indicated
that salmon movements decreased during periods of
highest flows (40,000 cfs) and increased as flows
subsided following major flow events (ADF&G
1982a).
It is hypothesized that increased water velo-
cities associated with peak f1ows discouraged
passage and encouraged milling (ADF&G 1982a).
Radiotelemetry investigation and gillnetting
indicated that the confluence of the Talkeetna,
Chulitna and Susitna Rivers is a chum, pink, coho
and chi nook mi 11 ing area and that sockeye, chum,
coho, pink, and chinook mill in the mainstem one
mile below Devil Canyon.
Chum were observed spawning at 10 sites and coho
at 4 of the 11 mainstem spawning sites identified
in the Devil Canyon to Talkeetna reach during
1982. Mainstem spawning appeared to be re-
stricted by lack of suitable spawning substrate
and ground water upwelling (ADF&G 1981c, 1982a).
Juvenile chinook and coho salmon use the mainstem
for overwintering. Salmon juveniles use the
mainstem for out-migration.
E-3-54
-
2.2-Species Biology and Habitat Utilization
( i i)
• Resident Species
Resident species, other than burbot and longnose suck-
er, primarily use this mainstem area as a migration
channel to spawning, rearing, and summer feeding areas
in the tributaries. No ma1nstem spawning or rearing
areas have been located. Rainbow trout and grayling
overwinter in mainstem habitats~
Burbot and l ongnose sucker use the ma i nstem as year-
round habitat. Burbot catches during low flows were
restricted to the mainstem and deep side channels.
During high flows, bur bot were captured at a greater
number of locations, including shallow side channels.
Slough Habitat
The clear water in the sloughs originates from local sur-
face runoff and ground water upwe l1 i ng. Ground water up-
wells in the slough channels throughout the year, thus
keeping these areas relatively ice free. in the winter.
Observations indicate the Susitna River is the primary
source of the water in many of the sloughs .. Local runoff
is a primary water source in slough habitats in the
summer.
The stage in the mainstem controls the water surface
elevation of the lower portion of the sloughs by forming a
backwater that can extend some distance upstream into the
slough1/. This backwater is divided into two parts-
clear water and turbid water. The ma·instem water creates
a turbid plug at the mouth of the slough that backs up the
clear water in the slough. As the stage in the mainstem
drops, the size and character of the backwater changes.
At summer flows of approximately 8,000 to 10,000 cfs at
Gold Creek {RM 136.8), the backwater recedes. This
reduces the depth of water at the entrance to the sloughs.
In some cases, the slough mouth and the mainstem become
separated by a gravel bar.
When high mainstem flows overtop the head end of the
sloughs, the flows flush the fine sediments that accumu-
late in the lower. portion of the sloughs. As peak flows
in the mainstem subside and the stage in the mainstem
drops below the head end of the slough, discharge through
the slough drops and the water in the slough begins to
clear.
l!Appendix E.2.A provides an incremental description of mainstem
discharge influence on slough hydraulic conditions.
E-3-55
2.2-Species Biology and Habitat Utilization
Because there is much diversity in the morphology of
individual sloughs, the flows at which they are
overtopped vary considerably. In general, most side-
channel sloughs are overtopped at flows between
20,000 and 24,000 cfs. Other sloughs are overtopped
only during flood events such as spring breakup.
In the summer, when mainstem temperatures are ranging
from 8° to Ire (46.4° to 53.6°F), intergravel tem-
peratures in the sloughs range from 4° to 6°C (39.2°
to 42.8°F). Some winter temperatures measured in the
sloughs and the mainstem indicate that when mainstem
temperatures range from 0.1° to 0.5°C (32.2° to
32.9°F), intergravel temperatures ranged from
2° to 4°C (35.6° to 39.2°F) (Atkinson 1982).
-Species Occurrence and Relative Abundance
• Salmon
Adults and/or juveniles of five salmon species
have been observed in slough habitat between
Devil Canyon and Talkeetna. Results of escape-
ment and spawning surveys indicated that adult
sockeye and chum salmon were the most numerous
salmon in these sloughs during peak spawning
periods (ADF&G 1981b, 1982e). In 1981, an esti-
mated 3526 chum and 2315 sockeye spawned in
sloughs in this reach, while in 1982 an estimated
3674 chum and 1402 sockeye spawned in these habi-
tats. Pink salmon were less abundant, with an
estimated 28 and 735 spawn-ing in sloughs in 1981
and 1982. In 1982, coho were observed spawning
in one of the sloughs (8A). No chinook have been
observed spawning in the sloughs. Spawning
counts for individual sloughs are reported in
ADF&G (1981b, 1983) (Figures E.3.12 to E.3.17).
Estimates of the total number of spawning salmon
by slough are given in Table E.3.12.
Studies of species occurrence and relative abun-
dance of juvenile salmon in slough habitat indi-
cate the following information:
Compared to other habitats in this reach,
juvenile chinook salmon are abundant in all
sloughs during winter and relatively abundant
in selected clear-water sloughs during summer.
E-3-56
-
-'
-l
-
2.2-Species Biology and Habitat Utilization
Juvenile coho salmon are abundant at slough
sites during winter and less abundant but
still present at slough sites during summer.
Preliminary data indicate that chum, pink, and
sockeye fry were present in slough habitat
during part of the summer •
• Resident Species
All resident species reported in this reach of
the Susitna drainage have been observed in slough
habitat between Devil Canyon and Talkeetna except
for lake trout.
Available data indicate that most species are
present in slough habitats as well as the main-
stem throughout winter. During summer, most
adult residents are not abundant in slough habi-
tat. Those that were relatively abundant in
slough habitat during summer included burbot,
longnose sucker, and rainbow trout. Previous
studies indicated that juvenile whitefish, gray-
ling, and rainbow trout were abundant in slough
habitat during late summer {Friese 1975).
-Significance of Habitat
Slough habitat between Devil Canyon and Talkeetna
is used by various anadromous species primarily for
spawning and also for rearing and overwintering of
juveniles; it is equally important for overwinter-
ing and rearing of various resident species. The
significance of slough habitat is discussed below
for species of commercial and recreational impor-
tance •
• Salmon
Slough habitat in this reach serves as spawning
habitat for sockeye and chum salmon and less
important spawning habitat for pink salmon
{Table E.3.12 and Figures E.3.12 to E.3.17).
In 1981 and 1982, 83 and 108 percent of the sock-
eye estimated to have passed Curry Station were
estimated to have spawned in sloughs in this
reach. For the same two years, 27 and 12 percent
of the chum salmon estimat~d to have passed Curry
Station, spawned in sloughs. Factors contri bu-
ting to the salmon spawning in the sloughs in
this reach are outlined below:
E-3-57
2.2-Species Biology and Habitat Utilization
Clear-water base flows originating from
sources such as ground water upwelling, local
surface runoff, or interstitial inflow insure
maintenance flows.
The presence of ground water upwelling in the
sloughs oxygenates spawning substrate, keeps
silt from compacting the spawning gravels, and
provides a stable temperature regime that
maintains incubating embryos through the
winter.
Sloughs also serve as rearing and overwintering
habitat for juvenile chi nook and coho sa 1 man.
During summer, tributary sites appear to be more
important chinook rearing habitat, although clear
water sloughs also provide rearing habitat. Coho
juveniles appear to use sloughs and tributary
mouth sites for summer rearing. The importance
of sloughs as ju veni 1 e overwintering and summer
rearing habitat may be related to:
Ice-free clear-water conditions during winter
compared to lowered flow and icing in coho and
chinook salmon natal tributaries; and
During high summer mainstem flow, the high
stage of the mainstem acts as a hydraulic con-
trol at the slough outlet, increas·ing the
depth of water in the lower end of the slough.
These clear-water areas promote benthic pro-
duction, which improves the quality of the
rearing habitat for juvenile salmon •
• Resident Species
Slough habitat between Devil Canyon and Talkeetna
provides overwintering habitat for adult rainbow
trout, grayling, and whitefish; year-round habi-
tat for adult bu rbot and 1 ongnose sucker; and
rearing habitat during 1 ate summer months for
juvenile whitefish, grayling, and rainbow trout.
The importance of sloughs as overwintering habi-
tat is related to the same factors as discussed
above for juvenile salmon.
(iii} Tributary Habitat
The depth of water in the mouth of tributaries
between Devil Canyon and Talkeetna is sensitive to
E-3-58
,....
I
I
2.2-Species Biology and Habitat Utilization
changes in mainstem flow. At high flows, the
mainstem creates a backwater at the tributary moQth,
thus increasing the water depth. The 1 i nea 1 extent
of the backwater in the tributary depends on the
stage in the mainstem and the gradient of the
tributary. At low mainstem stages, the backwater is
eliminated, resulting in shallower water and
increased flow velocities at the mouth.
Small deltas are formed at the mouth of most of the
tributaries. As the tributary enters the mai nstem
river, the change in gradient and subsequent change
in flow velocity cause the tributary to drop trans-
ported materials if the velocity in the mainstem is
not sufficient to carry the material downstream. As
the stage in the mainstem river decreases, the tribu-
taries become perched above the river, that is, the
tributaries flow across steep deltas. Were they to
remain under low mainstem flow conditions, upstream
passage of adult salmon and resident fish would be
inhibited or eliminated. However, based on studies
computed by R&M Consultants (1982f), the tributary
flows are sufficient to cut through the deltas to
establish a channel at a new gradient.·. In 1982, the
tributaries were observed to cut throught their
deltas during the low flows ·in August. Even during
the 1 ow August flows, most of the t ri butari es had
sufficient energy to move the delta material (R&M
Consultants 1982f).
-Species Occurrence and Relative Abundance
• Salmon
Except for sockeye salmon, the salmon species
present in the Susitna drainage were observed in
tributaries within the Devil Canyon to Talkeetna
reach. Spawning counts for individual tributary
index areas are given in ADF&G (1981b, 1982e)
(Figures E.3.12 to E.3.17).
Species occurrence and relative abundance of
juvenile salmon in tributaries or at tributary
mouths varied by season and by species. Results
of studies to date are outlined below:
E-3-59
2.2-Species Biology and Habitat Utilization
Juvenile chinook salmon are most abundant at
tributary mouths during summer. Redistribu-
tion of juveniles from areas of emergence in
tributaries to more favorable rearing habitat,
including the mouths of tributaries, occurs
throughout the summer as fish become more
mobil e.
Juvenile coho were slightly more abundant at
tributary mouth sites than at mainstem sites
during summer •
• Resident Species
All resident species except for burbot, longnose
sucker, and 1 ake trout were abundant in, and at
the mouths of, clear-water tributaries during
summer months. Limited information on winter
distribution and abundance indicates that few
resident fish overwinter in the tributaries.
-Significance of Habitat
• Salmon
Tributary habitat in this reach serves as primary
spawning habitat for chinook, coho, chum, and
pink salmon (ADF&G 1981b, 1983). Important
spawning tributaries include Indian River (chi-
nook, pink, chum and coho), Portage Creek (chi-
nook, coho, pink and chum), Gash Creek (coho),
Lane Creek (chinook and pink salmon), and Fourth
of July Creek (chinook, pink and chum) (Figures
E.3.12 to E.3.17).
Tributaries in this reach also serve as rearing
and summer feeding habitat for chinook and coho.
Tributary mouths also provide important milling
and rearing areas for ju veni 1 e chi nook and coho
salmon. Occurrence of age 0+ coho was
particularly high at tributary mouth sites (ADF&G
1982a) •
• Resident Species
Between Devil Canyon and Talkeetna, tributaries
provide spawning habitat, juvenile rearing areas,
and summer feeding habitat for several resident
species including rainbow trout, arctic grayling,
E-3-60
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-
, .....
-
2.2 -Species Biology and Habitat Utilization
(c)
round whitefish, and Dolly Varden (ADF&G 1981e,
1982a). In general, these fish migrate from
mainstem or slough habitat to the clear-water
tributaries to spawn in the spring (or early fall
for Dolly Varden). Once spawning is completed,
the fish move into favorable tributary habitat
for rearing and summer feeding. As freezeup
begins, the fish migrate from the tributaries to
the mainstem or deeper pools near the mouths of
tributaries.
Cook Inlet to Talkeetna
Below Talkeetna, the Susitna River is moderately to exten-
sively braided throughout most of the reach. From the inlet
to Bell Isl~Hld (RM 10), the river is separated into two
braided channels; from Bell Island to the Yentna River (RM
27), a single meandering channel is formed. From the Yentna
River to Sheep Creek (RM 70), the river is moderately to
extensively braided, with forested islands and non forested
bars between the channels of the river. The river is re-
duced to a single channel near the Parks Highway Bridge (RM
84), and braiding becomes moderate from this point to
Talkeetna. Gradients vary considerably in this reach. From
Cook Inlet to RM 50, gradient is 1 ft/mile (0.2 m/km); from
RM 50 to 83, it is 5.9 ft/mile (1.1 m/km); and from RM 83 to
Talkeetna, the gradient is 6.9 ft/mile (1.3 m/km). Typical
substrate in the reach is si 1t and sand with' some gravel and
rubble. Major tributaries include: Alexander Creek, Yentna
River, Kroto Creek (Deshka River), Chulitna River, and the
Talkeetna River. Flows in these tributaries are consider-
able. The Chulitna and Talkeetna Rivers contribute about 57
percent of the tot a 1 flow bel ow the confluence near
Talkeetna (R&M 1982c).
Study sites located in this lower reach included 11
tributary mouth sites, 5 tr·ibutary sites, 8 slough sites,
and 5 mainstem and side..,channel sites. The ranges for
physiochemical parameters in this reach are given in ADF&G
(1982a). The data collected include the following:
-Tributaries, sloughs, and the mainstem all exhibited high
dissolved oxygen readings (7.6-12.9 mg/1).
-Conductivity was generally low in the tributaries (19-46
umhosjcm) and moderately high in mainstem and slough sites
(29-216 umhos/cm).
-pH values were in the 6.1-8.0 range, with tributaries
having the lowest pH values.
E-3-61
2.2-Species Biology and Habitat Utilization
-Turbidity was lowest in tributaries, particularly Caswell
and Montana creeks (0.3-1.9 NTU), and highest at mainstem
and slough sites (2.2-255 NTU).
(i) Mainstem and Side Channels
Braided river reaches such as the 1 ower Susitna are
characterized by two or more interconnecting channels
separated by unvegetated or sparsely vegetated gravel
bars. The active floodplain is wide and sparsely
vegetated, and contains numerous high water channels
and occasional vegetated islands. Active channels
are typically wide and shallow and carry large quan-
tities of sediment at high flows. Bars separating
the channels are usually low, gravel-surfaced, and
easily erodible. The lateral movement of channels
within the active floodplain of a braided river that
carries large quantities of bed load is expected to
be high. The channels shift either by bank erosion
or by channel diversion into what was previously a
high-water channel. Gravel deposits may partially or
fully block channels, thereby forcing flow out of the
channel to develop a new channel.
Because braided river channels are wide and shallow,
they are more sensitive to flow reductions than the
deeper channels of a split channel system, i.e., a
drop in stage could result in a substantial reduction
in the width of the river and loss of large areas of
flow along the margins of the channel.
Because the thalwegs of the side channels are usually
at higher elevations than the main channel thalweg,
they are more sensitive to fluctuating river stages.
As a result, they may be completely dewatered at low
flows. Side channels are not subject to as high a
flow velocity as the main channels, thus the
substrate is not scoured from these channels as
easily. The water quality in the side channels is
the same as that found in the mainstem.
-Species Occurrence and Relative Abundance
Salmon
Adult salmon pass through this reach of the main-
stem during spawning migration. Generally, the
migration period extends from late May into
September (specific dates are reported in Section
2.2.l[a]). The relative abundance of adult
E-3-62
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2.2-Species Biology and Habitat Utilization
salmon in this reach is high because the entire
Susitna salmon run must pass through the lower
sections of the river in order to arrive at
spawning grounds. Population estimates of the
number of salmon that migrate to various escape-
ment monitoring stations are given in Table E.3.5
and Figure E.3.8.
With the exception of sockeye salmon, the
majority of upper Cook Inlet salmon are believed
to originate in the Susitna drainage and,
therefore, must migrate through portions of the
reach of mainstem between Talkeetna and Cook
Inlet.
Juvenile chinook salmon are relatively abundant
in this reach of the mainstem during winter
months. Juvenile coho are less abundant and more
often associated with tributary mouth sites •
• Other Anadromous and Resident Species
Other anadromous species observed in this reach
include Bering cisco and eulachon. Bering cisco
are abundant in the mainstem from August to
October (ADF&G 1982a). · Eulachon were observed in
the 1 ower 48 miles of the reach in 1982, and
lower 58 in 1981 (ADF&G 1983).
All resident species found in the Susitna drain-
age except for 1 ake trout were found in this
reach or the mai nstem. Lamprey were observed in
this reach but not in other reaches of the
Susitna River (ADF&G 198le).
-Significance of Habitat
• Salmon
The portion of the reach c 1 osest to Cook In 1 et
serves as a migration corridor for the entire
Susitna River salmon run.
Salmon spawning habitat in the mai nstem or side
channels of the reach is 1 i mited and is
comparable to the spawning habitat discussed for
the Devil Canyon to Talkeetna reach. Of the six
mai nstem or side channel spawning sites i dent i-
fied in 1981, chum salmon occupied six and coho
E-3-63
2.2-Species Biology and Habitat Utilization
salmon occupied one (Table E.3.13, ADF&G 1981a}.
No mainstem or side-channel spawning was observed
for chinook or sockeye salmon. Mainstem and side
channel spawning habitat is probably restricted
because of the 1 ack of suitable spawning sub-
strate and upwelling, which are two of the key
factors determining substrate suitability for
spawning.
Mainstem habitat also provides overwintering for
chinook and coho juveniles, limited summer rear-
ing habitat, and a migrating channel for smolt
outmigration •
• Other Anadromous and Resident Species
The mainstem from Talkeenta to Cook Inlet serves
as primary overwintering habitat and as an
important migration channel. Bering cisco and
eulachon are anadromous species that use the
mainstem as a migratory channel from Cook Inlet
to their respective spawning areas. Arctic gray-
1 i ng, rainbow trout, Dolly Varden, and round
whitefish are resident fish that use the mainstem
as a migratory channel to tributary spawning
habitat and as overwintering habitat. The move-
ment from tributaries to the mainstem for over-
wintering is inferred from capture data gathered
during the fall and spring near tributary
mouths.
Mainstem habitat in this reach provides possible
spawning habitat for at 1 east three species:
Bering cisco, eul a chon and bu rbot. Although
spawning activity by Bering cisco may occur
throughout the reach between RM 30 and RM 100,
three spawning concentrations were identified
(see Section 2.2.1(b)[i]). Bering cisco spawning
substrates were composed primarily of 1-to
3-inch (2.5-to 7.5-cm) gravel.
Bur bot and 1 ongnose sucker are present in the
mainstem throughout the year and utilize the
mainstem for overwintering, spawning, and juve-
nile rearing. Habitat utilization within the
mainstem is probably similar to that previously
discussed for the reach of mainstem between Devil
Canyon to Talkeetna.
E-3-64
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2.2-Species Biology and Habitat Utilization
( i i ) Slough Habitat
During periods of low flow, the sloughs below
Talkeetna are primarily fed by tributaries and ground
water upwelling and carry clear water. At high
flows, the sloughs are essentially overflow channels
for the mai nstem, and the water in the sloughs be-
comes quite turbid as it assumes the characteristics
of the mainstem water. Slough water clears as the
mainstem stage drops and turbid water no longer
enters the upstream end. Higher velocities associ-
ated with higher flows act to flush fine sediments
from the sloughs. Backwaters are created at slough
mouths when the river stage is high, but disappear at
low flows 0
-Species Occurrence and Relative Abundance
• Salmon
Chum, sockeye, and pink salmon adults were ob-
served in sloughs in this reach of the river
(ADF&G 1981b). No estimates of relative abun-
dance were made of the salmon using th'e slough
habitat in this reach.
Juvenile salmon occurrence and relative abundance
in slough habitat is similar to that reported for
the Devil Canyon to Talkeetna reach. Chi nook
juveniles are relatively abundant in slough habi-
tat during winter and less abundant during
summer. Juvenile coho are less abundant in
slough habitat than in tributaries in this reach
throughout the year (ADF&G 198ld) •
• Resident Fish
Occurrence and relative abundance of adult resi-
dent species in this reach of slough habitat is
similar to that discussed for the Devil Canyon to
Talkeetna reach. The majority of resident spe-
cies are present, and relative abundance is
highest beginning in late summer and continuing
throughout the winter. Adult residents that are
most abundant in slough habitat during summer
include burbot, longnose sucker, and rainbow
trout (ADF&G 1981e).
E-3-65
2.2-Species Biology and Habitat Utilization
Previous studies indicated that juvenile
whitefish, grayling, and rainbow trout were
abundant in the slough during late summer (Friese
1975).
-Significance of Slough Habitat
• Salmon
Based on spawning surveys upstream from
Talkeetna, slough habitat in this reach probably
serves as spawning habitat for chum, sockeye, and
pink salmon. Factors that may contribute to the
suitability of sloughs as spawning habitat are
the same as previously discussed for the Devil
Canyon to Talkeetna reach.
Slough habitat also serves as important rearing
and overwintering habitat for juvenile chinook
and coho salmon. The importance of sloughs as
juvenile overwintering and rearing habitat may be
related to factors discussed previously for the
Devil Canyon to Talkeetna reach •
• Resident Species
The significance of slough habitat downstream
from Talkeetna to resident fish is similar to
that discussed for the reach between Devil Canyon
to Talkeetna. Slough habitat in this reach is
utilized as overwintering habitat for adult rain-
bow trout, grayling and whitefish; year-round
habitat for adult burbot and longnose sucker; and
as rearing habitat during late summer for juve-
nile whitefish, grayling and rainbow trout. The
importance of sloughs as overwintering habitat is
related to the same factors as discussed previ-
ously for juvenile salmon species in the Devil
Canyon to Talkeetna reach. No spawning sites
were observed in the sloughs of this reach (ADF&G
198le).
(iii) Tributary Habitat
-Species Occurrence and Relative Abundance
Salmon
All of the salmon species present in the Susitna
drainage were observed in tributaries down-stream
E-3-66
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2.2-Species Biology and Habitat Utilization
from Talkeetna. Results of previous studies by
ADF&G (1980a, 1980b) and the 1981-1982 surveys in
the tr'ibutari es downstream from Talkeetna i ndi-
cate that the highest level of spawning for all
salmon species ·in this reach occurs in the
tributaries.
Species occurrence and relative abundance of
juvenile salmon in the tributaries or at tribu-
tary mouths varies by season and by species.
Results of studies to date indicate:
Juvenile chinook salmon are most abundant at
tributary mouth sites during summer; tributary
sites accounted for 95 percent of a 11 ju ve-
niles captured in this reach. During winter,
juvenile chinook were less abundant in the
tributaries, but were captured near tributary
mouths.
Juvenile coho were relatively abundant at
tributary mouth sites during both summer and
winter •
• Resident Species
All resident species except for burbot, longnose
sucker, and lake trout were most abundant in and
at the mouths of clear-water tributaries during
summer. Information on winter distribution and
abundance indicates that few resident fish
overwinter in tributary habitat.
-Significance of Habitat
• Salmon
Tributary habitat serves as the primary spawning
habitat for all salmon species occurring in this
reach.
Based on escapement counts and population esti-
mates at monitoring stations along the mainstem,
tributaries in this reach provide the majority of
spawning habitat for. chinook, coho, and pink
salmon in the Susitna drainage •
E-3-67
2.2-Species Biology and Habitat Utilization
Other Susitna River investigations have revealed
that all adult salmon mill to some degree in the
mai nstem and that it is not uncommon to find
adult salmon in the mainstem well upstream from
their spawning destination (ADF&G 1974, 1975).
Tributary habitat in this reach also supports
rearing and summer feeding habitat for juvenile
chinook and Coho salmon. Sites associated with
tributary mouths appear to provide particularly
important rearing areas for juvenile chinook and
coho salmon. Occurrence of age 0+ coho was par-
ticularly high at tributary mouth sites during
summer. In addition, tributary mouth sites in
these reaches appeared to provide overwintering
habitat for juvenile coho salmon •
• Other Anadromous and Resident Species
Tributary habitat in this reach, similar to the
Devil Canyon to Talkeetna reach, apparently pro-
vides spawning habitat, juvenile rearing areas,
and summer feeding habitat for rainbow trout,
arctic grayling, round whitefish, and Dolly
Varden (ADF&G 198le). In general, these fish
migrate during spring (early fall for Dolly
Varden) from the mai nstem or slough habitat to
clear-water tributaries to spawn. Once spawning
is completed, fish move into favorable tributary
habitat for rearing and summer feeding. As
freezeup begins, fish migrate from tributaries to
the mainstem or deeper pools near the mouths of
tributaries. Habitat characteristics that in-
fluence grayling distribution and abundance with-
; n tributary habitat are discussed for the
impoundment reach in Section 2.2.1(c)(iii).
2.2.3 -Streams of Access Road Corridor
(a) Stream Crossings
The access road to the Watana and Devil Canyon damsites will
depart from the Denali Highway and proceed south to Watana
(see Plate F-32, Exhibit F). From there, the road will tra-
verse the north side of the Susitna River to the Devil
Canyon damsite. A railroad spur from Gold Creek will con-
nect to Devil Canyon. The access road corridor, including
that portion of the Denali Highway to be upgraded as part of
the project, contains at least 45 streams and rivers in both
the Nenana and Susitna River drainages (Tables E.3.19 to
E.3.21).
E-3-68
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2.2-Species Biology and Habitat Utilization
The portion of the Denali Highway between Cantwell and the
Watana Access Road crosses 10 streams in the Jack River and
Nenana River drainages (Table E.3.18). Fish species present
in Jack River or Nenana River include grayling, northern
pike, burbot, whitefish and sculpin. Of these, the tri bu-
tary streams would contain at least grayling and sculpin.
From the Denali Highway to Watana, the road will cross Lily
Creek, Seattle Creek, and Brushkana Creek, as well as
numerous unnamed streams (Table E.3.20). These streams are
tributaries of the Nenana River, which supports populations
of grayling, northern pike, whitefish, burbot, and slimy
sculpin in this reach. Tributary streams are assumed to
contain at least grayling and sculpin.·
The upper reaches of Deadman Creek will also be crossed by
the Watana acc.e.ss road. This creek is a tributary of the
Susitna River and is considered important grayling habitat~
Between the Watana and Devil Canyon dams ites, the access
road will cross Tsusena· and Devil Creeks (Table E.3.21).
The streams contain grayling and may contain cottids, white-
fish, longnose sucker and Dolly Varden.
The road will cross the Susitna River approximately 2 miles
(3 km) bel ow the Devil Canyon dams it e. Salmon and probably
grayling, whitefish, cottids and longnose sucker occur in
the vicinity of the crossing. The habitat in this reach of
the Susitna is considered relatively non-productive compared
to reaches farther downstream.
The rail road between Devil Canyon and Gold Creek will cross
Jack Long Creek and Gold Creek (Table E.3.21). Jack Long
Creek contains small numbers of pink, coho, chi nook, and
chum salmon (Figure E.3.17). Gold Creek has been documented
to contain .chinook, and a few coho, and pink salmon (Figure
E.3.16). Three unnamed tributaries of the Susitna River
will also be crossed. These most likely do not contain fish
because of their steep gradients, but they are considered
important sources of clear water to Sloughs 19 and 20, which
are salmon spawning areas (Figure £.3.16).
(b) Streams Adjacent to Access Corridors
In addition to crossing streams, the Watana access road will
parallel some streams, particularly Deadman Creek. The
fisheries resources are described in Section 2.3.1(a) above.
Devil Creek will also be paralleled by the access road while
the railroad between Devil Canyon and Gold Creek will
parallel Jack Long Creek.
E-3-69
2.2-Species Biology and Habitat Utilization
2.2.4-Streams of the Transmission Corridor
Transmission lines will be built from Watana and Devil Canyon to
Gold Creek and from there to Anchorage and Fairbanks. From
Watana to Gold Creek, the transmission line route is within 1
mile ( 1. 6 km) of the Devil Canyon access road except near the
Watana Dam. At Gold Creek the transmission lines will use the
same right-of-way as the Anchorage-Fairbanks Interti~, which
extends from Willow to Healy.
Resources of the Intertie are described in Commonwealth et al.
(1982). At least 27 major salmon streams, including Willow
Creek, Kashwitna River, Talkeetna River, Chulitna River, and
Indian River will be crossed by the intertie and, presumably, by
the additional lines to be built in the right-of-way in conjunc-
tion with the Susitna Hydroelectric Project. The streams contain
grayling, rainbow trout, Dolly Varden, and cottids in addition to
salmon.
South of Willow, the transmission line will be routed between the
Susitna River and the Parks Highway for much of its length. It
will cross Fish Creek and the Little Susitna River as well as
many unnamed streams (Table E.3.22). The Little Susitna is a
productive fish stream and contains coho, pink, chinook, chum,
and sockeye salmon, as well as rainbow trout, Dolly Varden, and
grayling. Fish Creek is known to support chinook, sockeye, pink
and coho salmon, and rainbow trout. Many of the unnamed tribu-
taries to the Susitna River most likely provide salmon spawning
habitat.
An underwater crossing wll be used to cross the Kni k Arm. The
transmission line will then proceed east and south to the
University power substation. Knik Arm serves as a migration
corridor for five species of Pacific salmon as well as other
anadromous species such as Dolly Varden, Bering cisco, eulachon,
and lamprey. The transmission line will skirt Otter Lake, which
is stocked with rainbow trout, and will cross Fossil and Ship
Creeks. Fossil Creek is not considered a fish stream. Ship
Creek supports populations of pink, chum, coho, sockeye, and
chinook salmon as well as Dolly Varden and rainbow trout, but
because of the heavy development along its reaches, it is not
considered prime fish habitat. Planned construction of a diver-
sion wier for a power plant intake will block upstream movements
of anadr~omous fish prior to construction of the transmission
line.
North of Healy, the transmisson line will cross at least 50
creeks and rivers including the Nenana and Tanana Rivers
(Table E.3.23). These are two of Alaska•s major rivers and
provide habitat for salmon, grayling, whitefish, suckers, burbot,
E-3-70
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2.3 -Anticipated Impacts to Aquatic Habitat
cottids, northern pike, and inconnu. Panguinge Creek has been
documented to contain coho salmon, Dolly Varden and grayling
(Tarbox et al. 1978). The streams in the Little Goldstream
vicinity are not considered to be important fisheries habitat
because of their step gradients. While many of the streams go
dry in the summer, some do support grayling populations near
their mouths (Table E.3.23).
2.3 -Anticipated Impacts To Aquatic Habitat
Construction and operation of the proposed Susitna Hydroelectric
Project would result in both beneficial and detrimental impacts on the
aquatic habitat and associated fishery resources in the Susitna basin.
Many of the potehti al adverse impacts can be avoided. or minimized
through design and/or operation of the project, as described in Chapter
3, Section 2.4. This section examines the potential effects of the
project as proposed in Exhibit A and addresses the impacts likely to be
sustained as a result of project construction, reservoir filling, and
operation of Watana and Devil Canyon dams. Since the project is a
staged development, impacts to the aquatic habitat are presented by
project stage, phase, and river segment. The discussions focus on
important anadromous and resident species.
In this section, the term "impact" refers to a change affected on a
fish population or on its capability to utilize aquatic habitats,
resulting from project-induced changes in the physical characteristics
of the environment. Impacts refer to changes or effects that are both
beneficial and detrimental to rish populations. The project may alter
physical characteristics of the aquatic environment that do not affect
fishery resources, and therefore, these changes are not considered to
be impacts to the resources.
The description of impacts presented below is based on all available
data through spring 1982 including a significant portion of the data
from the summer 1982 field program. The types of impacts that have
occurred at similar projects have also been considered when describing
the probable impacts this project will have on the fishery resources.
The discussion represents the present understanding of the physical
processes, habitat relationships, and likely response of fishery
resources. The quantitative estimates of impacts presented in this
section will be refined as more site-specific data becomes available
from ongoing field programs. Data collection and analysis programs
currently planned or in progress will provide the information necessary
for a more refined quantitative impact analysis and mitigation plan.
The majority of the anticipated impacts resulting from the construction
and operation of the two dam development will occur during the first
phase of the development, the Watana Dam. Additional impacts but of a
significantly lesser magnitude would be sustained as a result of the
addition of the Devil Canyon Dam. The Watana Dam will be constructed
first and will alter the character of the aquatic environment
E-3-71
2.3-Anticipated Impacts to Aquatic Habitat
downstream from RM 238, the uppermost extent of the reservoir. The
magnitude of change in aquatic habitats below the damsites decreases as
the distance from the damsites increases. Alteration of the character
of existing aquatic environment would be most notable within the
impoundment and the 53-mile (88.3 km) reach between the Devil Canyon
damsite (RM 152) and Talkeetna (RM 99). Lesser changes are anticipated
in the 99-mile (165-km) reach from Talkeetna to Cook Inlet (RM 0).
Most of the potential impacts to aquatic habitat that arise from dam
construction will be avoided through careful design and siting, and by
employing good construction practices.
2.3.1 -Anticipated Impacts to Aquatic Habitat
Associated with Watana Dam
(a) Construction of Watana Dam and Related Facilities
Potential impacts to aquatic habitat associ a ted with the
construction of Watana Dam and related facilities can be
divided into three categories:
-Effects of permanent or temporary alterations to water
bodies, i.e., dewatering, alteration of flow regime, or
alteration of channels;
-Effects on water qua 1 ity i.e., changes in temperature,
turbidity, nutrients, and other water chemistry
parameters; and
-Effects, both direct and indirect, on fish population.
Table E.3.23 summarizes a number of the individual construc-
tion activities that would occur during the construction
period.
(i) Watana Dam
The period of construction considered for the pro-
posed Watana Dam consists of those activities occur-
ring from initial site preparation to the start of
reservoir filling. The proposed dam will consist of a
fill structure constructed between RM 184 and RM 185
of the Susitna River. The fill will be approximately
0.75 mile (1.3 km) wide, 0.75 {1.3 km) mile long and
885 feet (267 m) high. Over 63 million cubic yards
(47,880,000 m3) of material will be used to con-
struct the dam.
Prior to construction of the main fi 11 structure,
access wi 11 be completed; the diversion tunnels and
cofferdams will be completed and the river diverted
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2.3 -Anticipated Impacts to Aquatic Habitat
through the tunnels; and site-clearing activities
begun. Heavy equipnent will be brought to the site,
and construction material will be stockpiled in the
project area.
The two cofferdams will surround the area of the main
dam construction. One cofferdam will be built up-
stream from the damsite and the other downstream (see
Plate F 4 in Exhibit F). The upstream cofferdam will
be approximately 800 feet (242 m) 1 ong and 450 feet
(136m) wide; the downstream cofferdam will be 400
feet ( 121 m) 1 ong and 200 feet (60 m) wide. Water
blocked by the upstream cofferdam will be diverted
into two 38-foot (11.5-m) diameter concrete-lined
tunnels about 4100 feet (1242 m) long. The
cofferdams will be constructed during a two-year
period ( 1985.;, 1987) and wi 11 remain in use until
reservoir·filling begins.
The construction of -the main dam will have a number
of effects on the river and its biota. Some effects
will be the direct result of construction activities,
while other effects will result from alteration of
the river environment during construction. Impacts
will vary in duration and overall extent, some being
temporary or localized while others will be permanent
or more'widespread. ·
-Alteration of Water Bodies
The greatest alteration of .aquatic habitat during
construction of Watana Dam will occur at the dam-
site and at the mouth of Tsusena Creek where Borrow
Area E is 1 ocated. At the construction site, the
Susitna River flows through a confined valley with
a surface width of approximately 400 feet (121m).
The river bottom is sand, gravel and boulders. The
tributaries closest to the damsite are Deadman
Creek at RM 187 and Tsusena Creek at RM 182. Bur-
bot, sculpins, and longnose sucker probably occupy
the dams ite during the open water season and gray-
ling probably overwinter here (ADF&G 1981f).
The first major phase of dam construction involves
placement of the two cofferdams, thereby permanent-
ly dewatering 0.75 mile (1.3 km) of riverbed at the
damsite. It is anticipated that fish normally
using this stretch will move into adjacent habitats
and that the effects on population size will be
minimal. The dewatered area will eventually be
E-3-73
2.3 -Anticipated Impacts to Aquatic Habitat
covered by the Watana dam; thus, the effect will be
a permanent, but a relatively minor loss of aquatic
habitat and permanent blockage of fish movements·
through this reach.
Gravel mining will be an important activity asso-
ciated with construction of the dam and related
fac·ilities. A large portion of the material for
the main dam will be excavated from the north bank
of the Susina River at the confluence of Tsusena
between RM 180 and RM 182. Prior to inundation, it
can be expected that some impacts to aquatic habi-
tat will occur, such as increased erosion, removal
of bank cover, pending, dewatering, and increased
ice buildup caused by ground water overflow. In
the construction zone, Tsusena Creek is considered
more sensitive habitat than the mai nstem of the
Sus itna River. Anticipated impacts from gravel
removal operations include increased turbidity
caused by erosion and minor instream activities,
introduction of small amounts of hydrocarbons from
equipment operating in streams and the possibility
of accidental hydrocarbon spills. These impacts
wi 11 be temporary and are not expected to 1 ast
beyond site operation. A long-term impact to
aquatic habitat is expected at the mouth of Tsusena
Creek. The volume of material to be removed will
result in a large pit that will become filled with
water. This pit will produce increased lentic
habitat in exchange for lost riparian and upland
habitat. In order to avoid impacts to the aquatic
system, borrow sites will be located, planned, and
mined in accordance with the recommendations in
Section 2.4.3(d)(ii).
During summer flood flows, the operation of the di-
version tunnels will result in increased water
levels upstream from the damsite. During winter,
the water wi 11 be ponded to an elevation of 1470
feet (445 m) affecting about 0.5 mile (0.8 km) of
river upstream from the cofferdam. During the
summer, a flood event equal to the once-in-50-year
flood will cause a water level of 1536 feet
(465 m), thus causing backwater effects for several
miles upstream. Water velocities within the
tunnels during operations will act as a barrier to
E-3-74
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2.3 -Anticipated Impacts to Aquatic Habitat
upstream fish passage. Fish residing upstream from
the tunnels may be entrained into the flow and
transported downstream from the damsite. If river
transport mechanisms move rocks and other materials
into the tunnels, or if the tunnels are not smooth,
fish may be damaged through abrasion while being
transported downstream.
Experiments with fish transport indicate that fish
are adversely affected when exposed to velocities
in excess of 9.0 ft/sec (2.7 m/sec) (Taft et al.
1975). Tunnel velocities are expected to exceed 18
ft/sec (5.4 m/sec) during much of the summer
(Chapter 2, Section 4.1.1[a]), but because rela-
tively few resident fish are expected to occupy the
mainstem area immediately upstream from the tunnels
during the summer, little impact on populations is
expected (see Section 3.3.1[e] for description of
mai nstem fish habitats in this reach). To avoid
ice problems in the diversion tunnel during the
winter, a control gate will be partially closed to
create a head pond approximately 50 feet ( 15 m)
deep. Entrance velocities into the tunnel are
expected to be in excess of 20 ft/sec (6 m/sec)
{Chapter 2, Section 4.1.1[a]). Grayling and other
resident fish move into mai nstem habitat to over-
winter, and physical conditions within the head
pond will provide substantial overwintering habi-
tat. Entrance velocities of 20 ft/sec (6 m/sec)
are expected to entrain fish that are overwintering
in the head pond ·into the tunnel, probably result-
ing in fish mortality.
High discharge velocities at the downstream end of
the tunnels will scour gravels, sands and silts
from the immediate area of the tt1nnel outlet. The
velocities will also deter fish from using the area
immediately downstream from the tunnel (Bates and
VanDer Walker 1964; Stone and Webster 1976).
-Changes in Water Quality
The primary change in water quality that is ex-
pected as a. result of Watana Dam construction is
increased turbidity. Increases in turbidity will
vary with the type and duration of construction
activity and may be of severe 1 ocal consequence,
but are not expected to produce a widespread
det rimenta 1 effect u p.on aquatic habitat in the
Sus i tna River system. Some of the first
E-3-75
2.3 -Anticipated Impacts to Aquatic Habitat
construction activities to take place will include
clearing the areas, construction of access roads,
stockpiling of construction materials and fuel,
movement of heavy equipment, and construction of
support facilities. The construction of support
facilities and the access roads are discussed
bel ow.
Removal of cover vegetation may result in a number
of effects. The removal of cover will increase the
local run-off causing erosion, increased turbidity,
and increased dissolved solids (Likens et al. 1970;
Boreman et al. 1970; and Pierce et al. 1970). The
remova 1 of bank cover may a 1 so increase the expo-
sure of fish to predators, and 1 ead to a decrease
in fish populations (Joyce, et al. 1980b). Tem-
peratures in local areas may also increase.
The movement of fill materials and the actual pro-
cess of construction of the fill dam will contri-
bute to turbidity and siltation. During the trans-
port, storage, and plac:.f.ent of the 63 million
cubic yards {47,880,000 m ) of fill material used
in constructing the dam, a small percentage will be
introduced to adjacent water bodies including the
mai nstem Su sitna River through spi 11 s and erosion.
A loss of on! percent of 63 million cubic yards
(47 ,880,000 m ) represents approximately a 25
percent increase in suspended sediment in the main-
stem of the Susitna River. Thus, although the im-
pact on the mainstem may not be severe, the impact
on local clear-water streams could be significant.
Operation of heavy equipment in streams also in-
creases siltation and turbidity. The extent of the
impact of siltation and turbidity is dependent upon
the extent of machinery operation in the stream
beds and the substrate of the streams affected.
Finer substrates tend to be most affected (Burns
1970); but effects are also dependent upon stream-
flows in the local area. If velocities are suffi-
ciently high, deposition of suspended silts stirred
up by the machinery will not occur locally and the
effects would be minor (Shaw and Maga 1943). Since
velocities can be expected to vary seasonally, the
potential for impacts will vary seasonally as well.
E-3-76
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2.3 -Antictpated Impacts to Aquatic Habitat
Impacts caused by mac hi nery-i nduced s il tat i OR and
turbidity are expected to be more temporary in
nature than those resulting from streambank clear-
; ng.
Increased turbidity generally reduces visibility
and decreases the ability of sight-feeding fish to
obtain food (Pentlow 1944; Hynes 1966), thus effec-
tively reducing feeding habitat. Most fish species
will avoid turbid areas and many salmonids avoid
spawning in turbid waters. However, increased
turbidity is anticipated to be temporary, and asso-
ciated with actual clearing or gravel removal
activities and runoff from rainfall events.
Siltation (sedimentation) is also associated with
these activities. There is a considerable amount
of literature dealing with siltation effects on
fish (Burns 1970; Shaw and Maga 1943; Ward and
Stanford 1979) particularly the effect on spawning
and incubation. A general conclusion reached by a
review of the literature (Dehoney and Mancini
1982) is that the greatest adverse impact of silta-
tion is on immobile eggs and relatively immobile
larval fish. In general, siltation can cause sig-
nificant losses of incubating eggs and fry in
redds, particularly by interfering with oxygen
exchange. Areas of ground water upwe 11 i ng flow
would tend to be a·ffected to a 1 esser extent than
other areas because silt would tend to be prevented
from settling. Only resident fish ·in the vicinity
of Watana Dam, including Dolly Varden, arctic gray-
ling, and round whitefish, may be affected by sil-
tation. Entrainment of suspended materials would
also affect other water quality parameters, such as
dissolved oxygen, trace metals, and pH (Pierce et
al. 1970), but is not expected to produce wide-
spread detrimental effects upon aquatic habitat in
the Susitna system. ·
The production of concrete for tunnel lining, spil-
ling and powerhouse construction, and grouting will
generate concrete hatching wastewater. Peters
(1978) points out that the discharge of wastewater,
if untreated, can lead to detrimental effects on
fish populations and habitat. A particular problem
with concrete wastewater is the need to adjust its
pH (10+) prior to discharge.
E-3-77
2.3 -Anticipated Impacts to Aquatic Habitat
Waterbodies can be contaminated during construction
activities by petroleum products that enter from a
variety of sources. Fuels can enter streams, lakes
and wetlands from leaks in storage tanks and pipes
and from vehicle accidents during transportation.
Poor maintenance of vehicles can also allow small
quantities of hydraulic fluid, antifreeze, and fuel
to enter water bodies.
Diesel fuel will be used and will have to be stored
in large quantities o~site. New and used lubrica-
ting o"ils will also be commonly in use. There is a
great deal of 1 iterature (USEPA 1976; AFS 1979)
describing deleterious effects caused by oil
spills. Aromatics in diesel and gasoline are par-
ticularly toxic until evaporated. Heavier oils can
coat streambeds and aquatic vegetation and inter-
fere with production of food organisms consumed by
fish (Kolpak et al. 1973). In a river as large as
the Su sitna, small spills are expected to dilute
quickly and would likely cause harm. Spills into
smaller tributaries, especially while incubating
embryos are present, could impact resident popula-
tions. In the winter, it is difficult to recover
petroleum product spills that flow under ice in
rivers. Substantial mortality could result if
toxic substances reach overwintering fish and other
organisms. However, it is likely that any adverse
impacts that may occur from an oil spill would be
short-term.
Waste oils containing trace metals require handling
as a hazardous waste under 40 CFR 261-265. Sol-
vents. while probably present in rruch smaller
quantities than petroleum products, are usually
considerably more toxic to aquatic 1 ife. Other
chemicals of concern would include antifreeze,
hydraulic oil, "grease, and paints. The factors
that will affect the severity of the impact on fish
of a spi 11 are:
• The substance spilled;
• The quantity spilled;
• Frequency of spills in that area •
• The biota present;
• The life stages present;
• The season; and
Mitigation and cleanup plans and preparedness.
E-3-78
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2.3 -Anticipated Impacts to Aquatic Habitat
-Other Effects on Fish Populations
Other effects that instream construction activities
may have on fish populations include avoidance of
the area, injury, and mortality caused by instream
use of heavy equipment. Heavy equipment crossings
can also cause damage to incubating eggs and
preemergent fry if the crossing location passes
through a spawning area.
Water will be needed for production of concrete,
processing of gravel, and dust control during con-
struction. Fish impacts may result from entrain-
ment and impingement of juvenile fish as water is
withdrawn from local water bodies. However,
because low volume pumps equipped with proper
intake screens wi 11 be used, it is expected that
the number of fish affected will be low. The
potential for dewatering fish habitat in either the
summer or winter low flow period will be minimized
by pumping from streams with relatively high flow.
Current construction plans do not require instream
blasting. Blasting is planned for areas 500 feet
( 150 m) or more from streams. A review of the
effects of blasting on aquatic life (Joyce et al.
1980a, Appendix G) indicates that effects from such
b 1 ast i ng wou 1 d probab 1 y not be 1 etha 1 (at 1 east
with charges of 1 ess than 200 kg of TNT). The
transmitted shock waves from the blasting may dis-
turb fish and perhaps temporarily displace them
from areas near blasting activity. This type of
behavior is well documented for a variety of noise
sources (Vanderwalker 1967; Latvaitis et al. 1977;
and USEPA 1976). Secondary effects of blasting
include increased turbidity and siltation caused by
loosened soils and dust (see effects described
above). The extent of such effects would be depen-
dent upon the location and amount of blasting.
(ii) Construction and Operation of
Watana Camp, Village and Airstrips
During peak construction activity for the Watana dam,
faci 1 iti es to house a maxilllJm of 4720 people are
anticipated (see Exhibit A,· Section 1.13). The
faci 1 iti es rru st be 1 ocated adjacent to the construc-
tion site to simplify transportation to and from the
E-3-79
2.3 -Anticipated Impacts to Aquatic Habitat
camps. Two campsites are proposed: the construction
camp will be located near Deadman Creek about 2 miles
from the dam, and the construction village will be
within a mile of the site. Each developnent will
occupy approximately 170 acres (68 ha). After the
dam is completed, a permanent townsite will be
developed that encircles a 25-acre (10-ha) lake.
The construction camp will contain the management
offices, hospital, recreation hall, warehouses, com-
mu ni cations center, and bache 1 or dormitories, among
other facilities. It is anticipated that the camp
will be dismantled at the end of Watana dam construc-
tion, to be utilized during the Devil Canyon Dam
project. The constn..1ction village will be made up
of 320 temporary housing units and an additional 240
lots with utilities furnished. These temporary
housing units will be used primarily for workers who
are accompanied by families and wil 1 also be removed
when construction of Watana is complete. The perman-
ent town will be built to house the families of
employees who will form the operation and maintenance
team for Watana. The town will contain a hospital, a
school, gas station, fire station, store, recreation
center, and offices, as well as residences. Con-
struction of the town will not begin until the early
1990s, s i nee it will not be needed until Watana is
operational.
A 2500-foot (758-m) temporary airstrip will be built
approximately 1 mile (1.6 km) from the damsite at the
2200-2300-foot (667-697-m) level. A permanent air-
strip will be built about 5 miles (8 km) north of the
townsite. This strip will be 6000 (1818 m) feet
1 ong.
-Alteration of Waterbodies
Alteration of waterbodies resulting from the
construction of camps and related facilities will
be confined to the immediate area of the
development. Few adverse impacts are anticipated.
Gravel or other material required for facilities
construction will be mined from Borrow Site D.
Project facilities will be located away from water-
bodies to minimize the potential of increased
sediment input to water bodies. Overburden will be
stored in areas where it will not affect water-
bodies.
E-3-80
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2.3-Anticipated Impacts to Aquatic Habitat
Operation of the camps and airstrips is not expec-
ted to result in appreciable alteration of water-
bodies. The 1 ake within the townsite may ex peri-
ence some continued erosion from unstabilized
building pads, but this is expected to be minimal.
Water will be withdrawn from Tsusena Creek 6 miles
(10 km) upstream from its confluence with the
Susitna River for domestic use in the camp and con-
struction village. An estimated 1.5 cfs will be
required to meet peak demands in both the construc-
tion camp and construction village. This repre-
sents less than one percent reduction in flow dur-
ing the open-water season, and little impact is
expected to result from decreases of this magni-
tude. A reduction of approximately 8 percent is
expected during the winter period. A flow redu c-
tion of this magnitude is not expected to adversely
affect fish populations.
-Water Quality Changes
Changes resulting from camp construction are expec-
. ted to be similar to those experienced during dam
construction but much reduced in magnitude because
of the relatively great distance of the camp from
water bodies inhabited by fish. Turbidity and sus-
pended sediment levels will increase in areas where
erosion enters water bodies from such activities as
installation of the water intake system, but such
effects will be temporary.
During camp operations, the most significant im-
pacts on water quality will result from discharge
of treated wastewater into Dea~man Creek, oily and
silty runoff from the camps, water used for dust
control, and accidental fuel spills.
Current p 1 ans ca 11 for pumping water from Tsu sen a
Creek or a series of wells to supply the camps and
town during operations. Treated sewage during dam
construction will be discharged into Deadman Creek.
This sewage system wi 11 serve both the camp and
construction village and will be used for the per-
manent town after the temporary camp and vi 11 age
are removed. The solid waste 1 andfi 11 is situated
between the village and the camp. Fuel will be
stored within the village and the construction
E-3-81
2.3 -Anticipated Impacts to Aquatic Habitat
camp. Details of fuel storage and handling will be
developed by the construction manager in accordance
with accepted procedures.
The sewage treatment plant will include a biologi-
cal 1 agoon, which wi 11 provide secondary treatment
(Chapter 2, Section 4.1.l[g]). Secondary treatment
will avoid many of the problems associated with
primary treatment, such as decreased dissolved
oxygen and increased BOD, increased metals, and
bacterial counts, although it will introduce in-
creased levels of phosphorus and nitrogen ·into
Deadman Creek (Warren 1971). Also, if the dis-
charge is treated with chemicals such as chlorine,
residual levels may have detrimental effects upon
aquatic organisms. Rainbow trout in the Sheep
River in Canada were reported to avoid areas where
chlorinated sewage effluents were discharged, and
some fish mortality resulted (Osborne et al. 1981).
Grayling, the primary species in Deadman Creek, are
considered to be very sensitive to alterations in
water quality (Carl et al. 1967). The effects of
treated discharge into Deadman Creek and thence
into the reservoir will depend upon: (1) the water
chemistry of the creek and reservoir; (2) the com-
position of the treated sewage discharge; and (3)
the dilution of the discharge within the stream.
Storm drainage and oily water runoff are expected
tp occur at both the camp and the village, but will
be more of a concern at the camp, since this is
where the vehicle maintenance areas, shops, and
related facilities wi11 be located. By providing
proper drainage facilities. ponding areas, and if
necessary. pump stations to pump contaminated water
to the treatment facility, oily and silty water
wi 11 not reach Tsusena and Deadman Creeks. The
small 1 ake within the town 1 imits will be more
susceptible than the creeks to intrusions of oily
water, storm drainage, and fuel spills.
Adverse effects may also result from oily water
runoff from dust control on construction roads and
airstrips and from accidents involving vehicles
transporting fuels. The possible frequency and
severity of such occurrences cannot be predicted at
this time. Runoff from the solid waste landfill is
not expected to adversely impact any aquatic
habitat.
E-3-82
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2.3 -Anticipated Impacts to Aquatic Habitat
(b)
-Other Effects on Fish Populations
Disruption of fish populations during camp and village
construction is expected to be limited to areas of in-
stream activity and would be similar to those that may
occur during construction of Watana dam or access road.
Operation of the camps will result in increased access
to an area previously exposed to minimal fishing pres-
sure. The areas expected to sustain the -heaviest har-
vest pressure wou 1 d be those stretches of Deadman and
Tsusena Creeks and the Susitna River that are easily
accessible from the camps and the damsite. The resident
fish popu 1 at ions are thought to be at their maximum
level~ 1.-e., they are at their carrying capacity (ADF&G
198leJ. Studies to date have indicated a relatively
high percentage of 11 0lder 11 -age group fish (up to 9
years). Sportfishing will inflict heaviest impacts upon
larger, older fish and would likely result in a change
in the age distribution of the population .(Ricker
1963).
Filling Watana Reservoir
Filling of the Watana reservoir wi 11 impact aquatic habitats
both up and downstream from the dam. -The 9. 47 -million-acre-
foot reservoir is expected to take approximately three summer
runoff periods to fill (Table E~3.25). The length of time
required to fill the watana reservoir depends on the amount of -
runoff that occurs during the filling period. If low-flow years
occur, filling will be extended for an additional spring runoff
period. Table E.3.26 presents the flows expected at Gold Creek
during reservoir filling if average flow occurs in the Susitna
River. Expected flows at Gold Creek exceed minimum target flows
proposed during reservoir fi 11 i ng in a 11 but the second year of
filling, when the target flows are provided. Winter flows
(November-April) are reduced slightly in April during the first
winter of fi 11 i ng and are unaffected from November to Apri 1 in
the second winterl/. -
Impacts to downstream fisheries are summarized in Table E.3.27.
These habitat alterations will result in changes to all trophic
levels of the aquatic community presently functioning in the
area.
liThe effects of various mainstem flows on hydrologic characteristics
of sloughs are presented in Appendix E.2.A of Chapter 2 of Exhibit E.
E-3-83
2.3 -Anticipated Impacts to Aquatic Habitat
During filling, downstream releases will be made through one
of the diversion tunnels. The tunnels are low-level
discharge structures with limited capability to control
downstream water temperatures (Chapter 2, Section
4.1.2[e][i].
(i) Watana Reservoir Inundation
Filling the Watana reservoir wi 11 inundate 38,000
acres (15,200 ha). The reservoir will flood 54 miles
(90 km) of Susitna River mainstem habitat and 28
miles ( 46.7 km) of tributary habitats that wou 1 d be
converted from 1otic to lentic systems with accom-
panying changes in hydraulic characteristics, sub-
strate, turbidity, temperature, and nutrient levels.
These habitat alterations will result in changes to
all trophic levels of the aquatic community preSently
functioning in the area. Figure E.3.21 shows the
area to be inundated by the Watana reservoir.
Reservoir filling will begin in May 1991 with the
spring runoff flows. The greatest changes in water
surface elevation and the most significant impacts
will occur during the first year (see Table E.3.25).
During May of the first year, the water surface ele-
vation of the reservoir will rise an average of
5 feet (1.5 m) per day reaching a depth of approxi-
mately 165 feet (50 m) by the end of the month (an
elevation of 1625 feet, or 492 m). Increases in
water surface elevation of 3 feet (0.9 m) and 4 feet
(1.2 m) per day are predicted in June and July,
respectively. At the end of the first year, the
reservoir will encompass an area of approximately
13,000 acres (5200 ha). It is expected to have a
surface elevation of 1875 feet (568 m) and depths of
425 feet (128.8 m).
-Mainstem Habitats
Impoundment of the Susitna River by Watana dam
will alter the physical characteristics of mainstem
habitats and consequently affect the associated
fishery resources. Burbot, 1ongnose sucker, and
whitefish generally occupy mainstem habitats year-
round. Arctic grayling use mainstem habitats for
overwintering (ADF&G 1981f). Mainstem habitats
would be eliminated by the impoundment and replaced
by a reservoir environment. The expected physical
characteristics of the reservoir are presented ·j n
Chapter 2, Section 4.1.1.
E-3-84
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2.3 -Anticipated Impacts to Aquatic Habitat
At present~ mainstem habitats are utilized by bur-
bot during the open-water season. Longnose sucker
and whitefish generally occupy mai nstem habitats
only in the vicinity of tributary mouths (ADF&G
1981f). Burbot~ longnose sucker, and whitefish are
found in glacial 1ake environments in south-central
and southwestern Alaska (Bechtel Civi1 and
Minerals~ Inc. 1981; Russell 1980). Since these
fish are associated with habitats similar to those
that will be present ·in the reservoir~ conditions
within the reservoir during fi 11 i ng are not
expected to adverse1y affect these species. Thus~
these species are expected to utilize the reservoir
habitats year-round after the reservoir is fi1led.
White.fish and burbot spawning areas may be 1ocated
in mainstem habitats near tributary mouths. These
areas will be inundated during the first year of
filling~ eliminating their present value as spawn-
ing areas. Since the habitat in the vicinity of
tributary mouths would be changing rapidly, it is
unlikely that stable spawning areas (similar to
those presently existing) would develop during
reservoir filling. The loss of spawning habitat is
expected to adversely affect bu rbot and whitefish
production in the proposed impoundment. However~
since the water surface elevation during reservoir
fi 11 i ng remains constant from November through
April~ the spawning and incubation periods for both
burbot and whitefish~ any spawning that does take
p1ace would probably be successful.
Water depth~ water quality, and food avai.l ability
are critical factors associated with overwintering
habitat (Bustard and Narver 1975; Tripp and McCart
1974; Tack 1980). The reservoir is expected to
provide adequate depth and water quality conditions
for overwintering fish. At the end of the first
year of filling, water depths would exceed 400
feet. Turbidity 1eve1s of the impoundment are
expected to be suitable for fish, although slight1y
higher than existing winter turbidity 1eve1s in the
mainstem Susitna River. Particles less than 5
microns in diameter are expected to remain in sus-
pension (Chapter 2, Section 4.1.2 [e][iii]).
Studies report fish overwinter in 1 ake habitats
with suspended g1acial flour levels similar to and
greater than those expected for the Watana reser-
voir (Russell 1980; deBrugn and McCart 1974). When
E-3-85
2.3 -Anticipated Impacts to Aquatic Habitat
filled, the reservoir wi 11 have a surface area of
approximately 38,000 acres (15,200 ha), which
greatly increases the amount of habitat having
suitable conditions for overwintering fish. The
increase in overwintering habitat may have a
beneficial impact on fish resources of the upper
Susitna basin above the Watana dam, if lack of
available overwintering habitat presently 1 imits
fish populations in the area.
Winter reservoir water temperatures may increase
the quality of overwintering habitat in the upper
Susitna Basin. Reservoir temperatures in the top
100 feet {30m) are expected to be in the range of
1 to 2°C (33.8 to 35.6°F) (Chapter 2, Section
4.1.3[e][i]). Present winter water temperatures in
mainstem habitats in the proposed impoundment area
are near ooc (32°F). These warmer water tempera-
tures may benefit fish by increasing the overwinter
survival rate. During the winter of 1981-1982,
fish apparently sought out water with warmer tem-
peratures in the lower Susitna River. Other inves-
tigators have reported that fish prefer warmer
water areas in the winter (Umeda et al. 1981).
-Tributary Habitats
Filling the Watana reservoir will inundate portions
of six tributaries (Table E.3.28): Deadman,
Watana, Kosina, Jay, and Goose Creeks and the
Oshetna River (Figure E.3.21). All of these tribu-
taries support grayling populations, and grayling
that depend on habitats inundated by the reservoir
will be displaced and may be lost.
The initiation of reservoir filling in May 1991
coincides with grayling spawning activities. In
the project area, arctic grayling spawn in the
clear water tributaries during spring breakup, and
the embryos take approximately 11 to 21 days to
develop (Morrow 1980). Most of the spawning activ-
ity appears to take place in the lower portion of
the tributaries. Spawning areas in the six streams
will be inundated in May and June of the first year
of filling. The water surface elevation is fore-
cast to increase at a rate of 5 feet (1. 5 m) per
day during the spawning period, with increases of
3 feet (0.9 m) per day during the latter part of
the incubation period.
E-3-86
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2.3 -Anticipated Impacts to Aquatic Habitat
During the grayling spawning period, streams gene-
rally carry increased sediment loads from high
spring flows and ice breakup. The sediments
carried by the stream will be deposited at their
confluence with the reservoir as a result of the
reduced stream velocities associated with backwater
conditions. The resultant sedimentation will de-
posit on the spawning bed, and embryos on the
stream bottom will likely be covered with sediment
and suffocate. Longnose sucker may spawn in tribu-
tary mouths during the spring (ADF&G 1981f), and
they are expected to experience the same effects as
grayling.
Arctic grayling depend on tributary habitats for
summer rearing areas. Grayling are not expected to
occupy reservoir habitats during the summer as they
are not found in lake habitats with turbidity
levels similar to those projected to occur in the
reservoir (Russell 1980) (see Chapter 2, Section
4.1.2[e][iii] for projected impoundment turbidity
levels}. Grayling densities in tributaries are
high, averaging 323-1835 fish per mile in 1982
(Table E.3.17), which indicates that available
summer habitats are occupied (ADF&G 1981f, 1982e).
Grayling occupying tributary habitats inundated by
the reservoir will 1 ikely be 1 ost because of 1 ost
feeding habitat. A small percentage of these gray-
1 ing are expected to remain in the reservoir near
tributary mouths.
Approximately 2. 3 miles (3. 8 km) of Deadman Creek
will be inundated by the reservoir at full pool.
Presently, a waterfall located about 1 mile
(1. 6 km) upstream from the mouth prevents upstream
fish migration. The reservoir will inundate this
barrier and allow fish passage to the upper Deadman
Creek and Deadman Lake. Since the available limit-
ing habitats in Deadman Creek are presently occu-
pied by grayling, this is not expected to cause
significant increases in the populations.
Dolly Varden will be only slightly affected by the
inundation. Dolly Varden occupy a wide range of
habitat types in south-central Alaska including
glacial lakes with a wide range of water quality
(Russell 1980). In the project area, Dolly Varden
are residents occupying tributary habitats during
E-3-87
2.3 -Anticipated Impacts to Aquatic Habitat
the open-water season and after spawning return to
the mainstem to overwinter. It is anticipated that
Dolly Varden wi 11 occupy reservoir habitat year-
round.
Dolly Varden spawn in the fall, the embryos incu-
bate through the winter, and the alevins emerge in
the late spring. Since the reservoir is not fil-
ling during the spawning and incubation period, any
spawning areas available in the fall would not be
affected before emergence.
-Lake Habitats
Sally Lake (Figure E.3.21) and several other small
lakes will be inundated by the reservoir. Sally
Lake has populations of lake trout and grayling
that appear to be stunted (ADF&G 198lf). Si nee
grayling populations are not usually associated
with glacial lakes or turbid water, the grayling
population will likely be lost. Lake trout will be
able to survive in the reservoir if an adequate
food base exists. Lake trout are found in glacial
1 akes, i ncl udi ng Chakachamna and Kontrashi bun a
Lakes {Bechtel Civil and Minerals, Inc. 1981 and
Russell 1980), with physical characteristics simi-
lar to those expected in the Watana reservoir.
(ii) Watana Dam to Talkeetna
Table E.3.26 presents a comparison of average monthly
pre-project flows and projected monthly flows at Gold
Creek during initial reservoir filling. The greatest
change to the system wi 11 occur during the summer
season. The filling phase of the Watana development
will alter streamflows, water quality, and water tem-
peratures downstream from Watana dam to Talkeetna
(Chapter 2, Section 4.1.2). The second open-water
season of filling {May 1992 through October 1992) is
scheduled for minimum releases and is thus discussed
below as maximum expected impact, unless otherwise
noted.
-Mainstem Habitats
Mainstem habitats in this reach can be divided into
two segments: from Watana Dam to RM 152 in De vi 1
Canyon and from RM 152 to Talkeetna {RM 99). High
velocities associated with natural flows through
E-3-88
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-
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2.3 -Anticipated Impacts to Aquatic Habitat
Devil Canyon normally appear to prohibit upstream
passage of fish beyond RM 152. Thus, anadromous
fish are prevented from using habitats upstream
from the canyon except during dry years when flows
are 12,000 to 15,000 cfs or less. During 1982, one
of the driest summers on record, chinook salmon
ascended to RM 156.8 but were not reported upstream
from that point.
During the open-water season (June through October)
mainstem habitats below Devil Canyon are primarily
used as a migratory corridor by adult and juvenile
fish as they move to and from spawning and rearing
areas that are located in other habitat types asso-
ciated with the river. A few isolated salmon
spawning areas have been identified in the mainstem
(ADF&G 1981b, 1982e). Some juvenile salmon rear in
this hab.itat type in low densities during most of
the open-water season. Juvenile salmon from other
rearing areas and resident fish move into mainstem
habitats for overwintering as the river clears in
late fall (ADF&G 1981d, 1981e). Several resident
species, including burbot, whitefish, and longnose
sucker, occupy mainstem habitats year-round (ADF&G
1981e). Upstream from Devil Canyon, mainstem habi-
tats are used by bur bot, sculpin, 1 ongnose sucker,
and whitefish year-round and by arctic grayling for
overwintering habitat {ADF&G 198lf) •
• Altered Flow Regime
A variety of changes will occur in mainstem
habitats as a result of the proposed Watana
reservoir-filling schedule. Flows will be sub-
stantially reduced during the spring period.
With the exception of the first year, average
monthly flows in May and June will be reduced to
approximately 6000 cfs from pre-project average
annual flows of 13,300 and 28,100 cfs, respec-
tively (Table E.3.26). Decreases of this magni-
tude will affect the physical processes in this
reach, which in turn will affect fish associated
with this habitat ty~e.
Filling flows during May and June will affect the
ice removal process in this reach. Presently,
the natural flows increase during May, causing a
mechanicaJ breakup of the ice cover, and rapidly
transport large chunks of ice and attached sedi-
ment downstream. The force to raise and fracture
E-3-89
2.3 -Anticipated Impacts to Aquatic Habitat
the ice cover is the result of rising stream
flows caused by rapid snowmelt and is common to
many Alaskan rivers. Under the filling schedule,
mechanical breakup will tend to be less severe in
the mainstem and unlikely to occur in side-
channel or slough habitats. Thus, ice scouring
and bank gouging would be reduced. The potential
for ice jams and resultant flooding would be
diminished (Chapter 2, Section 4.1.2[e][ii]).
Outmigration of salmon fry and smolts generally
occurs in June, apparently on the receding limb
of the high spring flows. Flows of 6000 cfs
would not affect downstream migrations in main-
stem habitats because sufficient depth and velo-
cities would exist to transport fry or smolts.
Predicted depths and velocities at all 65 sur-
veyed cross-sections between Devil Canyon and
Talkeetna indicate that at 6000 cfs, minimum
depths would exceed 2 feet (0.6 m) (Figure
E.2.10).
Flows of 6000 cfs would persist until the last
week of July. Chinook salmon are passing through
the system in late June and July to spawning
habitats in tributary streams. These fish hold
in mai nstem areas to mature before moving into
the tributaries (ADF&G 1981b). Many of the hold-
ing areas available at flows of 20,000 cfs would
probably not be available at 6000 cfs. however,
other suitable holding areas are expected to
exist under the low-flow conditions resulting
from filling the reservoir.
During June and July of the second and third
years of filling, flow velocities in Devil Canyon
are not expected to block all upstream fish
passage. Chinook salmon would likely be able to
pass through the canyon and utilize spawning
habitat available in tributaries upstream from
Devil Canyon and bel ow Watana Dam. Telemetry
studies located chinook salmon in the lower Devil
Canyon reach (RM 150.4 to 151.5) in late June and
early July 1982 (ADF&G 1983). In August. spawn-
ing chinook salmon were observed in the mainstem
at the mouth of Cheechako Creek (RM 152.5) and in
an unnamed creek {RM 156.8), both upstream from
the Devil Canyon damsite. High velocities
blocked migrations past RM 156.8 (ADF&G 1982d).
E-3-90
,---
r
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i"
2.3 -Anticipated Impacts to Aquatic Habitat
According to 1982 USGS provisional streamflow
data, flow levels dropped to 17,000 cfs at Gold
Creek in early July, then rose to 25,000 for the
remainder of the month. Since the telemetry
studies located chinook salmon just downstream of
Devil Canyon in late June, the salmon probably
passed through the canyon in early July when the
flows had dropped. High flows in 1981 prevented
them from migrating past RM 151.7 (AOF&G 1981b}.
With the filling flow of 6000 cfs in June and
July, the entire canyon is expected to be
passable by chinook $almon, allowing them to
enter Tsusena, Fog, and Devil Creeks (RM 178.9,
173.9, and 161.0).
Pink, chum, and coho salmon spawning areas in the
mainstem are expected to be adversely affected by
the flows proposed in the filling schedule.
These spawning areas are generally small, iso-
lated areas on the river margins or behind veloc-
ity barriers (AOF&G 1981a, 1983). Lateral areas
are more susceptible to changes in flow. The
quality of these habitats wi 11 be degraded
through reduced depth and velocity; some areas
may be completely dewatered.
Fall flows at Gold Creek drop rapidly under the
filling schedule (Table E.3.26}. Under the fil-
ling flows, the river would reach 2000 cfs in
October, whereas flows of 2000 cfs do not nor-
mally occur until November. In addition, the
entire ice formation process will be delayed 3 to
4 weeks later than normal, and the staging will
be less than normal. Thus, the stage during
filling in October would be reduced, decreasing
the wetted perimeter. Spawning areas of summer
and fall spawning fish, such as salmon and white~
fish, are expected to be adversely affected by
receding flows •
• Altered Temperature Regime
Since the diversion tunnels will function as low-
l-evel intakes, the thermal regime of the Susitna
River from Watana Dam to Talkeetna will be
altered (Chapter 2, Section 4.1.2[e][i]). Down-
stream water temperatures during the first open-
water period of reservoir filling (May through
E-3-91
2.3 -Anticipated Impacts to Aquatic Habitat
October) will be similar to pre-project tempera-
tures, with some lagging. During fall, the
reservoir will retain heat longer and will gradu-
ally cool to 4°C (39.2°F). Winter temperatures
above Devil Canyon are expected to range from 2
to 4°C (3S.6° to 39.2°F). When the water reaches
RM 160, water temperatures are expected to be
near 0°C (32°F) (pre-project levels).
Temperatures during the second open-water season
will be substantially reduced. Water released at
Watana Dam will be approximately 4°C (39.2°F).
Because of the large water volume (12,000 cfs in
August) and the high average water velocities
(3-4ft/sec or 0.9-1.2 m/sec), water temperatures
during August are expected to be in the range of
so to 6°C (41° to 42.8°F) at Talkeetna. At the
beginning of the third year of filling, the
reservoir water surface elevation is expected to
be 2083 feet {631.2 m), high enough to utilize
the multiple level intake structure (Figure
E.2.10S). This will provide sufficient control
to release water near 10°C (S0°F) during July,
August, and early September (Figure E.2.174).
Lower water temperatures during the second season
of filling may adversely affect fish populations
in the reach from Watana Dam to Talkeetna. Pro-
jected water temperatures of so to 6°C ( 41 o to
42.8°F) are well below normal water temperatures
of 10° to l2°C (S0° to S3.6°F) in August. Under
natural conditions, pink salmon have been repor-
ted to migrate at S°C (41°F) in Russia, while 7°C
( 44. 6°F) is the 1 owest reported migration tem-
perature bel OW S0°N latitude (Bell 1983). For
coho salmon, 4°C (39.2°F) is the lowest recorded
temperature at migration in northern stocks,
while 7°C (44.6°F) is the lowest temperature
below S0°N latitude. In the Columbia River, coho
movements ceased at approximately 6°C (42.8°F)
(Bell 1983). In northern areas, chinook have
been reported moving at 4°C {39.2°F), sockeye at
2.S 0 to 4°C {36.S 0 to 39.2°F), and chum at l.S°C
(34.7°F). These observations are not directly
applicable for predicting the impacts associated
with the temperature reduction during filling
since they represent natural migrating tempera-
tures. Salmon returning to the Susitna River
will begin migrating in the near-normal tempera-
ture regime in the lower river and then encounter
E-3-92
-
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r
i
2.3 -Anticipated Impacts to Aquatic Habitat
reduced temperatures at Talkeetna. These lower
temperatures are expected to increase mi 11 ing
behavior and delay the migration into the reach
upstream from Talkeetna. Portions of some
stocks, particularly pink and coho, will likely
not enter the reach and will select alternative
spawning areas. For those adults that enter the
reach, the mainstem temperatures are expected to
slow the rate of migration and retard sexual
maturity. These impacts wi 11 result in reduced
productivity in this reach during the second year
of filling. Slough and tributary temperatures
wi 11 be unaffected, so adults that reach these
normally-used spawning areas would resume natural
spawning activity.
Lower water temperatures during the second open-
water season are expected to adversely affect
resident and juvenile anadromous fish that uti-
lize mainstem and side-channel habitat. Feeding
activity~ and growth are closely carrel ated with
water temperature (Clarke et al. 1982}. Colder
water temperatures may reduce growth during the
open-water season. Juvenile salmon have been
found to avoid cooler water when possible
(Bustard and Narver 1975). Thus, fish may avoid
main stem and side-channel habitats and move to
warmer water in tributary and slough habitat.
-Side-Channel Habitats
Many of the physical changes identified for main-
stem habitats would also occur in side-channel
habitats. Since the side channels are generally
characterized by higher streambed elevations at
their upstream than the mainstem bed elevation at
that location, the forecasted changes in streamflow
are expected to cause greater effects in side-
channel habitats. During the open-water season,
side-channel habitats are used for passage by sal-
. mon and rainbow trout; for spawning by pink, chum
and coho salmon; and for summer feeding areas by
longnose sucker, burbot, and whitefish (ADF&G
198lb, 1981d, 1981e, and 1983). Little juvenile
salmon rearing has been reported in side-channel
habitats during the open-water season (ADF&G
1981e).
E-3-93
2.3 -Anticipated Impacts to Aquatic Habitat
As in mainstem habitats, the greatest changes would
occur in the spring because of the substantial flow
reductions from pre-project flows (Table E.3.26).
Many side channels that normally convey water in
May, June and the first three weeks of July may be
dewatered under filling flows.
Decreased mainstem flows would l·ikely result in
decreased depths and velocities in some side-
channel habitats and complete dewatering of others.
This is expected to alter or eliminate the availa-
bility or suitability of currently used spawning
habitat.
It is unlikely that new spawning areas will become
available in side channels under the filling flows.
Side-channel habitats with a streambed elevation at
their upstream end that is 1 ow enough to convey
water during the reservoir filling process are
expected to have substrate that is too 1 arge for
spawning. Under natural conditions these side
channels are subject to peak flows that have
removed most of the gravel substrates, 1 eavi ng the
streambed armored with large cobbles and boulders
(R & M Consultants 1982c). It is unlikely that the
substrate in these areas would change as a result
of the project. Thus, the use of these areas by
spawning fish would continue to be limited by sub-
strate.
Reduced flows in the spring may inhibit emergence
and outmigration in some side-channel spawning
areas. At times, spawning areas can be substan-
tially dewatered but the embryos can be maintained
by intergravel flow that allows development to
proceed. Normally, increased spring streamflow in
these areas pro vi des water for emergence and out-
migration. Filling flows are not expected to be
sufficient to provide streamflow in some of these
areas.
Filling flows will alter the hydraulic conditions
of the side channels that are not dewatered. Lower
discharges will decrease velocities, depths, and
wetted perimeters. This is expected to improve the
quality of these areas as rearing habitat for some
resident and juvenile anadromous fish. Juvenile
fish are generally found in association with low
E-3-94
(~---'
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r
2.3 -Anticipated Impacts to Aquatic Habitat
velocities (ADF&G 1982, ·Wilson et al. 1981; and
Environaid 1982). Burbot, longnose sucker and
whitefish are also found in waters with a low
velocity, but require greater depth.
Use of these areas by juvenile salmon may be pre-
sently limited by lack of a food source. Benthic
production is limited by ·the high summer turbid-
ities and scouring effects of suspended sediments.
Under filling flows, turbidity would be decreased
(Chapter 2, Section 4.1.2[e][iii]), allowing
greater light penetration; the scouring effect of
the greater pre-project flows would also be reduced
(Chapter 2, Section 4.1.2 [d]). Some side channels
above Talkeetna will be completely dewatered under
. the proposed filling flows, thus eliminating any
rearing or feeding habitat normally supported by .
pre-project flow levels. Benthic production from
these areas would also be lost. The increase in
production because of greater light penetration and
reduced scouring in flowing side channels is expec-
ted to be much greater than the loss expected from
dewatering some of the side channels.
Stream temperatures during filling in side-channel
habitats wi 11 be similar to mainstem habitats (see
previous section).
-Slough Habitats
Slough habitats in the Watana Dam to Talkeetna
reach have been identified as the most important
spawning areas directly influenced by the Susitna·
River. Sockeye, chum, pink, and coho salmon have
spawned in 20 of the 34 s 1 oughs found above the
confluence with the Chulitna River (see Figures
E.3.12 to E.3.17) •. Juvenile coho and chinook have
been found uti 1 i zing these areas as rearing and
overwintering habitat (ADF&G 198ld). Rainbow
trout, burbot, longnose sucker, and whitefish have
been found in these habitats at various times of
the year (ADF&G 1981e).
Sloughs in this reach of the river resemble con-
fined side channels. In general, they function as
overflow channels and convey turbid water from the
mainstem at high flows. During mainstem flows of
less than 20,000 cfs, clear water originates from
E-3-95
2.3 -Anticipated Impacts to Aquatic Habitat
surface runoff and
through the slough
(Refer to Section
Appendix E.2.A.)
ground water upwelling and flows
channel into the mainstem river.
2.2.2[c] of this chapter and
Preliminary conclusions from a study of Slough 9 indi-
cated that ground water upwelling, and in part, flow, in
this slough is related to the stage of the mainstem
Susitna R1ver (Trihey 1982d). At the slough upwelling
locations that are within the mainstem backwater, the
ground water gradient between mainstem and slough is
relatively unaffected by discharge until backwater
effects are no longer present at the upwelling location.
Hence, upwelling rates in backwater areas would remain
virtually unchanged until the area is no longer affected
by backwater. At locations where slough upwelling is
unaffected by mai nstem backwater effects, the reduced
gradient will result in reduced slough upwelling rates.
Under reservoir filling conditions, discharge will be
reduced to about 1000 cfs at Gold Creek during the
freezeup period. This will result in reduced staging
compared with pre-project ice-staging levels. Hence,
during w·inter, the mainstem slough water level differ-
ential will be reduced with a corresponding reduction in
upwelling area. Reduced upwelling would affect the
quality and quantity of both spawning and rearing habi-
tat presently available in the systeml/.
Filling flows will cause passage problems for adult
salmon moving from the mainstem and side-channel habi-
tats into slough habitats. Based on field observations
during the low flows of August 1982, Susitna streamflows
in the range of 12,000 to 14,000 cfs, combined with
extremely low surface runoff into the sloughs, hampered
or restricted the passage of adult salmon into several
s 1 oughs. The water depth at the slough entrance is a
function of the water surface elevation of the mainstem
and the discharge from the slough2/. An increment-
al analysis was performed on the effects of various dis-
charges on access of adult salmon into Slough 9. Data
obta1ned during the 1981 and 1982 field seasons indicate
that the flow from Slough 9 is quite small unless the
mainstem has overtopped the alluvial berm at its up-
stream end (Trihey 1982d). Upstream passage into Slough
9 by adult chum salmon would not appear to be restricted
when mainstem discharges were 18,000 cfs or higher.
Access becomes
l/Additional information is presented in Appendix E.2.A.
_£/This relationship is presented in Appendix E.2.A for sloughs SA, 9,
and 21.
E-3-96.
(.,' i
-
r
-
2.3 -Anticipated Impacts to Aquatic Habitat
increasingly more difficult as mainstem discharge
decreases. An acute access prob 1 em exists at
streamflows of 12,000 cfs and less (Trihey 1982d).
In general, upstream access into Slough 9 is some-
what more difficult than an average entrance condi-
tion encountered by adult salmon in the Devil
Canyon to Ta 1 keetna reach. Upstream access into
Slough 9 is easier than access to Slough 16B or 19;
but more difficult than access into Whiskers Slough
or Slough 8A. It is a reasonable index of entrance
conditions into Sloughs 20 and 21 (Trihey 1982d).
Under Watana filling conditions, only the backwater
areas would be affected. Surface runoff, which is
controlled by rainfall, and snowmelt and ground
water upwelling contribute, to the flow in the
sloughs. The flow in the slough controls the phy-
sical characteristics of the habitat upstream from
the backwater during the open-water season.
A reduct ion in mai nstem stage may degrade and
reduce spawning habitat in the sloughs. Adult
sockeye and chum appear to seek out areas with
upwelling ground water in which to spawn. If a
reduction in mainstem discharge reduces the amount
of upwelling or the area influenced by upwelling,
spawning habitat will be reduced or may be el imi-
nated. In a worst case scenario, if all upwelling
ceased such that all slough spawning was elimi-
nated, the spawning area used by approximately 3700
chum in 1982, 2300 sockeye in 1981, and 740 pink,
salmon in 1982 would be eliminated (Table E.3.12).
Losses of this magnitude would reduce the total run
size by 11,840 chum; 9200 sockeye and 3550 pink
salmon, assuming harvest in escapement ratios of
2.2:1; 3.0:1; and· 3.8:1, respectively (Friese
1975). The sockeye that spawn in the sloughs
upstream from Talkeetna, however, are considered to
be strays from Chulitna and Talkeetna River stock
(ADF&G 1983). If this is true, and this segment of
the run is not self-perpetuating, then the run size
of sockeye would not be reduced.
Since juvenile fish occupy habitats with a rela-
tively wide range of depth, decreases in the depth
of sloughs are expected to have little effect on
the utility of rearing habitat. The greatest
impact to juvenile habitat would occur if the
reduction in depth a 1 so eliminates or reduces the
utility of cover objects associated with slough
E-3-97
2.3 -Anticipated Impacts to Aquatic Habitat
habitats. In addition to object cover, young
chinook have been observed occupying the interface
between the turbid and clear-water portions of the
backwater at the mouth of the slough. Under the
proposed flow regime during reservoir filling, the
amount of this particular habitat would be reduced
by decreased backwater effects. Additional rearing
habitat, however, is expected to become avail ab 1 e
in mainstem and side-channel habitats. (These
habitats are discussed in their respective
sections.)
The reduction of mainstem flows during the spring
and the altered breakup process may affect out-
migration from slough habitats. It is thought that
changes in water levels and temperatures trigger
out-migration in young salmon. Fish were observed
to outmigrate on the receding edge of the high
flows in spring 1982. Under the filling schedule,
the high flows during the spring would be elimi-
nated. However, flow from 1 ocal runoff waul d be
unaffected, and this flow and rising water tempera-
tures should be sufficient to stimulate fry to
out-migrate from the sloughs (Thomas 1975).
Under filling flows, increased beaver activity is
expected to have an adverse effect on adult salmon
utilization of slough habitats. The elimination of
spring breakup flows will allow beaver to become
established in most sloughs. During the low flows
of August 1982, beaver dams located in Slough 8A,
inhibited use of upstream slough habitats by adult
salmon. An increase in beaver dams, however, would
increase rearing habitat for juveni 1 e chi nook and
coho.
-Tributary Habitats
Compared with other habitat types in the reach from
Watana Dam to Talkeetna, tributary habitats receive
the largest salmon escapement (Section 2.2.2(b)
[iii]) of this chapter; ADF&G 1981b and 1983).
Tributaries also provide important spawning habitat
for grayling and rainbow trout and rearing habitat
for chinook and coho salmon juveniles (ADF&G 1981d
and 1981e).
With the except ion of tributary mouths, tributary
habitats below the impoundment will not be affected
by the proposed project. Seasonal variations of
E-3-98
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-
-
2.3 -Anticipated Impacts to Aquatic Habitat
the mainstem discharge changes the hydraulic
conditions associated with the tributary mouths.
During the open-water season, the present stage in
the mainstem river causes a backwater to form at
the tributary confluences. The backwater area
provides rearing habitat for resident species and
juvenile salmon (ADF&G 1981d and 1981e) and
facilitates passage of upstream migrants into the
tributary.
lower mainstem flows during filling will reduce the
backwater effects and decrease water depths at
tributary mouths. Rearing fish are not expected to
be impacted since similar backwater areas will
reform in mainstem habitats downstream from tribu-
tary mouths.
A reduction in the stage of the mai nstem river
could cause some tributaries to become perched and
impede migration by adult salmon and resident fish
to upstream areas. As the tributary enters the
mainstem river, the change in gradient causes the
tributary water to drop transported materials.
These gravels and sand form small deltas at the
mouths of tributaries (Figure E.2.140). As the
stage in the mainstem recedes, the tributaries
become perched above the river. Since the flow in
the tributaries is not regulated, the tributaries
would continue to experience peak high flows. In
most tributaries that support fish, these high
flows will be sufficient to down cut through the
delta material to establish a channel at a new
gradient (R&M Consultants 1982f). Jack Long (RM
144.8), Sherman (RM 130.9), and Dead horse
(RM 121.0) Creeks are the only streams used by
adult salmon that may remain perched under the
proposed filling flows (R&M Consultants 1982f).
Although adult pink salmon have been documented in
Dea<:thorse and Sherman Creeks, it is quest i onab 1 e
whether winter flows that drop be 1 ow the surface
can support successful salmon production.
An incremental analysis of access into Portage
Creek and Indian River under project operational
flows indicated that access by adult salmon is not
expected to be a problem (l:.rihey 1983}. If the
tributary channels remain perched and mainstem
flows are near 8000 cfs, tributary discharge will
E-3-99
2.3 -Anticipated Impacts to Aquatic Habitat
provide sufficient depth to maintain access. Velo-
cities near the confluence of both tributaries are
also not expected to block access. It is anticipa-
ted that the t ri butari es wi 11 down cut to a new
streambed equilibrium (R&M Consultants 1982f) at a
depth approximately the same magnitude as the
difference between the water surface elevation
associated with the most prevalent summer discharge
of the mainstem.
The reduced flows through Devil Canyon will allow
chinook salmon access to tributaries upstream from .
the rapids that have historically b1ocked sa1mon
migrations (see mainstem section). Under the fi11-
ing regime, chinook salmon will have access to
Cheechako Creek ( RM 152. 5) and the unnamed tri bu-
tary at RM 156.8 {Figure E.3.6) on an annual basis.
In addition they are expected to have access to
Tsusena, Fog, and Devil Creeks at RM 178.9, 173.9,
and 161.0, respectively (Figure E.3.6). There
appears to be adequate habitat in these creeks to
allow for salmon production. Thus, the Watana
development will increase the availability of
spawning habitat in tributaries in this reach.
Future development of the Devil Canyon dam wou1d
subsequently eliminate access to these tributa-
ries.
(iii) Cook Inlet to Ta1keetna
Project effects below Ta.lkeetna are expected to be
considerably reduced in magnitude from those pre-
sented for the Watana dam to Ta 1 keetna reach. Just
upstream from Talkeetna, the Chulitna and Talkeetna
rivers join the Susitna River. These rivers contrib-
ute 39 and 18 percent, respectively, of the stream-
flow in this reach {R&M Consultants 1981c). Many
other major tributaries enter the Susitna in this
reach {Figure E. 3. 3). In order to evaluate the
streamf1 ows in this reach, two streamflow stations,
the Sunshine and Susitna stations, were established.
Tables E.3.29 and E.3.30 present a comparison of
pre-project and proposed fi 11 ing flow regimes for
these stations.
Si nee the project will have no effect on the tribu-
tary basins, project-related physical changes in the
Susitna River below Talkeetna will be of less magni-
tude than physical changes above Talkeetna. Impacts
E-3-100
~~----
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2.3 -Anticipated Impacts to Aquatic Habitat
to fish habit at s be 1 ow Ta 1 keet na are expected to be
limited since only minor changes will occur in physi-
cal characteristics of mainstem habitats. Physical
characteristics of side channels are generally more
susceptible to changes in mainstem discharge and the
proposed filling flows may affect side-channel habi-
tats.
-Mainstem Habitats
During the open-water season, mainstem habitats in
this reach of the Susitna River are used primarily
for passage and limited spawning. The reach exten-
ding from approximately RM 4.5 to RM 29 is almost
entirely eulachon spawning habitat sustaining a
spawning adult population ranging in the millions
of fish {ADF&G 1983}. In addition, spawning areas
for chum salmon and Bering cisco have been located
(ADF&G 1981b, 1982d,e and 1983}. To date, few
rearing fish have been found in this reach (ADF&G
1981d}. Resident fish including burbot, whitefish,
and longnose sucker occupy mainstem habitats during
the open-water season (ADF&G 1981e).
Little change is expected in water temperature or
turbidity in this reach. The Chulitna River car-
ries a much heavier sediment load and has approxi-
mately the same discharge. as the pre-project
Susitna River at their confluence (R&M Consultants
1981d). Under the proposed filling schedule, the
water from the Susitna River would comprise approx-
imately 14 percent of the streamflow below the con-
fluence of the Chulitna and Talkeetna rivers in
July and 25 percent in August. The influence of
the Chulitna and Talkeetna rivers would dominate
the thermal, water chemistry, and suspended sedi-
ment characteri sties of the 1 ower Susitna River
(Chapter 2, Section 4.1.2[e][iii]).
Only a small reduction in the number and magnitude
of peak flows from Talkeetna to Cook Inlet is anti-
cipated. Si nee the project controls such a small
portion of the runoff in this reach, a 1-in-2-year
flow event at Susitna Station would become a 1-in-5
or 1-in-10 year event (R&M Consultants 1982}.
Thus, high, turbid flows in the lower Susitna River
may still inhibit fish passage at times as well as
limit benthic production.
E-3-1 01
2.3 -Anticipated Impacts to Aquatic Habitat
Under the proposed fi 11 i ng schedule, average
monthly streamflow in July and August would be
reduced by a maximum of 28 and 17 percent at
Sunshine Station (Table E.3.29). Because of the
channe 1 geometry of the mai nstem, flow reductions
of this magnitude would probably not change the
utilization of mainstem habitats with regard to
salmon passage and resident fish summer activities.
The reductions in depth resulting from this
decrease in streamflow waul d not create passage
problems. Nor is it 1 i kely that summer feeding
areas waul d be e 1 imi nated. Flow reductions may
have a more significant effect on spawning habitat,
since this habitat tends to be located on the
lateral margins of the mainstem and in side channel
a rea.
Most salmon-spawning areas in the mainstem are
located in broad or braided segments that are more
sensitive to changes in flow. Small changes in
stage near the threshold value necessary to overtop
the upper end of the braided channels can poten-
tially result in large changes in the availability
of spawning areas within the braided area.
Salmon and Bering cisco spawning habitats may be
subject to greater changes, since they occur
primarily in the upper portion of this segment from
RM 75 to 81 ( ADF&G 1982a and 1983). Bering ci sea
spawned in mai nstem habitats from RM 75 to RM 81
during October 1981 (ADF&G 1982b, and 1983). Dur-
ing filling, October flows would be reduced by 9
percent the second year and by 26 percent the third
year at Sunshine Station (Table E.3.29). Reduc-
tions 1 ess than 10 percent are not expected to
impact fish as changes in depth and velocity are
small. Reductions of 26 percent may reduce Bering
cisco spawning habitat.
Eulachon spawning areas would be subject to the
least amount of change, since they occur in the
lower part of the reach, RM 4.5 to 58 (ADF&G 1982d
and 1983). Eulachon spawning areas were identified
by ADF&G during spawning surveys in May 1982 in
areas adjacent to cut banks and riffle zones or
bars with moderate velocity where the substrate
included deposits of unconsolidated sands and gra-
vels. Because of the channel geometry in the
E-3-102
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I"'"'
!
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2.3 -Anticipated Impacts to Aquatic Habitat
broad, braided floodplain of this reach, similar
habitats are e~pected to exist in this portion of
the river under the proposed fi 11 i ng schedule.
Reductions in 1 ong-tenn, average monthly stream-
flows of 12 percent (from 60,500 to 53,100 cfs) are
predicted at Susitna Station during May (Table
E.3.30). Even if some of the habitat presently
utilized is dewatered, habitat available along the
margins of the floodplain under the filling flows
will provide replacement habitat.
Winter streamflow reductions are not expected to
affect habitat utilization in the mainstem below
Ta·l keetna. Low winter flows can stress overwinter-
i ng fish and embryos and are often a 1 imit ing fac-
tor for fish populations in Alaska. In the Susitna
River, flow generally reaches its lowest level in
March. Flow reductions are not projected during
this period (Tables E.3.29 and E.3.30). Therefore,
overwintering success of fish or developing embryos
in mainstem habitats is not expected to differ from
existing conditions.
Spring breakup flows will be decreased during fill-
ing. Average monthly flows in May and June wi11 be
reduced by 26 percent at Sunshine Station and by 12
percent at Susitna Station. This reduction is not
anticipated to adversely affect outmigrating salmon
smolts in mainstem habitats; neither is it expected
to affect the spawning migration of rainbow trout
or grayling as they move to the tributaries.
-Side-Channel Habitats
Many of the effects identified for the mainstem
under the proposed filling schedule would also
pertain to side-channel habitats. Mainstem flow
generally controls the characteristics of side-
channel habitats; however, changes in stream dis-
charge can result in greater effects on side-
. channel· habitats 'than on mai nstem habitats. As in
mainstem areas, water temperature and turbidity are
expected to be similar to existing conditions below
Talkeetna.
During the open-water season, side-channel habitats
are used for passage by adult and juvenile salmon
and resident fish; for spawning by chum salmon; and
for summer feeding areas by longnose sucker, burbot
E-3-103
2.3 -Anti~ipated Impacts to Aquatic Habitat
and whitefish. Only limited rearing of juvenile
salmon has been observed in this habitat type dur-
ing the open-water season.
Reductions in streamflow during August may dewater
some salmon-spawning habitat in side channels. Six
side-channel spawning areas were identified below
Talkeetna in 1981; none were found in 1982 (Table
E.3.13). Salmon spawning activity in this habitat
type is generally located in side channels with
relatively high streambed elevations at their up-
stream end. These areas are protected from the
high scouring flows and are able to retain sub-
strates suitably sized for spawning. The high
streambed elevation also makes them susceptible to
dewatering under reduced mainstem discharge. The
lower streamflows proposed during August may reduce
the availability of spawning habitat in these
areas.
The proposed filling flow regime may affect rearing
habitat in side channels below Talkeetna. Side
channels have a gradation of streambed elevations
from high overflow channels to low, nearly contin-
uous flow channels. The effect of reduced stream-
flows on rearing habitat will depend on the stream-
bed elevation of the side channel. Some rearing
habitat for juvenile anadromous and resident fish
will be lost if side channels dewater or water
depths become too shallow. Generally, reduced
flows increase the available rearing area as young
fish prefer low velocities (ADF&G 1982a, Wilson et
al. 1980, and Environaid 1982). If side channels
with suitable streambed elevations exist in this
reach, new rearing areas should become available
where the flow reductions result in decreased velo-
cities but still maintain sufficient depth. Thus,
the potential exists for the location of the rear-
ing habitat to change, but the availability of
rearing habitat would be similar to pre-project
levels.
Rearing habitat and summer feeding areas may be
limited by the availability of food in side-channel
habitats. Suspended sediment 1 oad and peak flows
contribute to low benthic production in the Susitna
River. Since little change is expected in these
parameters below Talkeetna (R&M Consultants 1981,
1982c), the change in hydraulic characteristics is
E-3-104
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2.3-Anticipated Impacts to Aquatic Habitat
not expected to be sufficient to increase utiliza-
tion of these habitats by anadromous juveni 1 e and
resident fish as feeding areas.
-Slough Habitats
Few sloughs below the confluence of the Chulitna
River have been extensively sampled. Slough habi-
tats in this reach have been identified as rearing
and possible spawning areas (ADF&G 198lb, 1981d,
1981c). Many of these areas are influenced by
tributary streams and, to a lesser degree, by the
mainstem of the Susitna River. Chum, pink and
sockeye salmon spawn in slough habitats below the
Chulitna confluence. Juvenile coho and chi nook
salmon have been found using these areas for rear-
ing and· overwintering (ADF&G 198ld). Rainbow
trout, burbot, longnose sucker, and whitefish U$e
these habitats seasonally (ADF&G 198le).
Sloughs in the Talkeetna to Cook Inlet reach may be
generally affected in the same way as sloughs above
Talkeetna. The magnitude of predicted change in
mainstem flow is less in this reach; therefore, the
magnitude of changes to slough habitats and the
resultant impacts to fishery resources are expected
to be smaller.
-Tributary Habitats
The tributary habitats in the Talkeetna to Cook
Inlet reach of the Sus i tna River are not expected
to be significantly affected by the project. The
project would not alter any of the existing physi-
cal processes in the tributaries with the excep-
tion of the area near tributary mouths. The main-
stem creates a backwater at the mouths of the tri-
butaries, which provides habitat for rearing juve-
niles and resident fish (ADF&G 1981de).
The stage in the mai nstem controls the extent of
these backwater areas. Flow reductions under the
proposed filling schedule may alter the physical
characteristics of the tributary mouths in the
upper portion of this reach. During the open-water
season, mai nstem discharge wi 11 be reduced by 12 to
34 percent at Sunshine Station (Table E.3.29).
Reductions in flow in June (34 percent) and July
{28 percent) may reduce the areal extent of these
backwaters.
E-3-105
2.3 -Anticipated Impacts to Aquatic Habitat
Tributaries that enter the mai nstem Susitna River
in the lower portion of this reach should be mini-
mally affected, since the percent change in dis-
charge will be relatively small. Flow reductions
ranging from 13 to 8 percent are anticipated from
June through August at Susitna Station (Tab1e
E. 3. 30). Tributaries are not expected to become
perched because of these reductions in mainstem
discharge.
During the winter, tributary mouths provide impor-
tant overwintering habitat and may provide spawning
habitat for burbot. Because there will be no
reduction in mainstem discharge during the ice
covered season, winter conditions are expected to
remain the same as pre-project conditions.
(iv) Estuary
Since only minor increases in salinity are antici-
pated during reservoir fi 11 i ng, impacts to fishery
resources are not expected.
(c) Operation of Watana Dam
Operation of Watana dam will substantially alter the physi-
ca1 environment both upstream and downstream from the dam.
A summary of major downstream impacts, both beneficial and
adverse, is presented in Table E.3.31.
(i) Reservoir Habitats
The Watana reservoir wi 11 have an area of approx i-
mately 38,000 acres (15,200 ha) with depths up to 735
feet (223m). The reservoir will experience an
annual drawdown of about 95 feet (28.8 m) from 2185
feet (662 m) above mean sea level to 2090 feet
(633 m). During a dry year, such as occurred in
WY1970, the lowest operational level will be 2075
feet (629 m) occurring at the end of April (Chapter
2, Figure E.2.149). The minimum acceptable level for
operation is 2065 {626 m) feet or a total drawdown of
120 feet (36m) {Chapter 2, Figure E.2.169). Water
quality conditions expected in the reservoir are
discussed in Chapter 2, Section 4.1.2(e) and are not
expected to preclude fish utilization of the
reservoir.
E-3-106
-
-
2.3 -Anticipated Impacts to Aquatic Habitat
Habitat potential of the reservoir is considered to
be 1 imited because of 1 ow productivity. The reser-
voir will be oligotrophic because of summer turbidity
levels of 30-40 NTU, (Chapter 2, Section 4.1.3[c])
while the 95-foot (28.8-m) October to May drawdown
will inhibit development of a 1 ittoral zone. Thus,
food availability may limit fish populations in the
reservoir.
As discussed under reservoir filling (Section
2.3.1(b), limited populations of grayling burbot,
lake trout, whitefish, and Dolly Varden are expected
to ut i1 i ze the reservoir year-round. An analysis of
spawning habitats in relation to the annual drawdown
cycle was performed to evaluate the potential for
successful reproduction in the reservoir. Filling of
the Watana reservoir will usually be initiated in
May, at a minimum pool level of about 2090 feet
(633 m), and continue through August or early
September as the water surface elevation reaches its
maximum 1 evel {2185 feet [662 m] 1 n wet years) a
95-foot {28.8-m) vertical ga·in (Figure E.3.22).
Annual reservoir filling will progressively inundate
main stem and tributary habitats. Reservo·i r drawdown
will commence in October and continue through the end
of April as water levels decline to an average mini-
mum elevation of 2090 feet (633 m) above mean sea
level. Tributary and mainstem habitats of the
Susitna River and shoreline habitats in the reservoir
wi 11 be progressively dewatered during the winter
season.
Arctic grayling select spawning sites within lotic
habitats (Morrow 1980). Embryo incubation conse-
quently occurs within tributary reaches, indicated as
being above the reservoir water surface elevation in
Fiyure E.3. 22. Grayling within the Watana reservoir
will spawn in tributaries upstream from the minimum
reservoir pool iri May and June. Rising water surface
levels (Figure E.3.22) will cause sediment deposition
in spawning areas resulting in mortalities to devel-
oping embryos. (This is discussed in Section 2.3.1
[b][i].) Survival of grayling embryos is thus
expected to be low within r~aches of tributaries that
are inundated during May and June. Figure E.3.22
indicates that grayling embryos incubating below an
elevation of. 2133 feet {646 m) will be inundated
prior to hatching. Embryos spawned above 2133 feet
(646 m), a vertical rise of 30 to 35 feet (9 to
10.6 m) above the water surface elevation at the time
E-3-107
2.3 -Anticipated Impacts to Aquatic Habitat
of spawning, will not be affected. Table E.3.28
shows the length of the major tributaries that will
be inundated during the May to June period.
Lake trout, humpback whitefish, and burbot are expec-
ted to spawn within the reservoir during the fall and
winter with embryos incubating during winter and
spring (Figure E.3.22). In Alaska and British
Columbia, 1 ake trout spawn in September and October
at depths from 3 to 110 feet (0.9 to 33m); humpback
whitefish spawn in October and November within 20
feet (6 m) of the surface; and burbot spawn in
December within 20 feet (6 m) of the surface (Morrow
1980).
The decrease in water surface elevation during winter
is expected to dewater humpback whitefish and burbot
embryos {Figure E.3.22). Lake trout embryos depos-
ited above an elevation of 2120 feet {642 m) wi 11 be
dewatered while those spawned below a depth of 65
feet (19.7 m) (elevation 2120 feet [642 m]) in
September and October are expected to survive.
Dolly Varden embryos, which are deposited in tribu-
taries during the fall, will not be affected by the
drawdown cycle.
As presented in Section 2.3.1(b)(i), reservoir habi-
tats w·ill provide overwintering habitat for grayling,
lake trout, burbot, whitefish, longnose sucker, and
Dolly Varden.
(i i) Watana Dam to Talkeetna
-Mainstem Habitats
The primary impacts of Watana operation on the
mainstem habitats between Talkeetna and Watana
are,
• Altered seasonal flow regime;
• Altered temperature regime;
• Reduced sediment load downstream of the dam; and
• Altered water quality parameters •
• Open-Water Season
Open water post-project flows in the mai nstem
would be substantially reduced from pre-project
conditions. Predicted reductions in average
E-3-108
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2.3 -Anticipated Impacts of Aquatic Habitat
monthly flows at Gold Creek range from 22 to 62
percent of pre-project flows over the period of
May. through September (Table E.3.32). Secondary
impacts of reduced flow include,
•• Decreased flow velocities;
Decreased depths in many mainstem habitats;
•• A reduction in the number and magnitude of
flood events in this reach of the Susitna
River; and
Decreased sediment transport.
Because use of mainstem habitats appears to be
limited in part by high velocities, decreased
streamflow and the corresponding decrease in
velocity may improve the utility of mainstem
habitats for both resident and anadromous fish.
Prior to construction of Devil Canyon dam, chin-
ook salmon will be able to pass through the can-
yon, which is presently unpassable, and utilize
spawning habitat available in tributaries up-
stream from Devil Canyon and below Watana dam.
Operating flows are higher than filling flows
from May through July and are thus expected to
·provide greater depths than filling flows (Sec-
tion 2.3.2 (b)[ii]). Depths associated ·with
operation flows are generally not expected to
significantly decrease wetted perimeter because
of the rectangular channel configuration of
existing mainstem areas. Depths are expected to
be sufficient for fish passage.
The significant reduction in the number and mag-
nitude of flood events in this reach of the
Susitna River can have several beneficial effects
on mainstem habitats. Presently, the Susitna
River at Gold Creek carries peak flows of 75,000
to 80,000 cfs (10-year frequency). These flows
transport 1 arge amounts of sediment, scour the
riverbed, and remove most of the suitable spawn-
ing gravels. Reduction of these peak flows would
reduce these habitat disruptions. In addition,
recent studies of high streamflows of 38,500 cfs
in August 1981 (ADF&G 198lb and 1982a) indicate
that flows of this magnitude inhibit upstream
migration of adult salmon. Migration resumed
when the flows receded. Operation of the project
E-3-109
2.3-Anticipated Impacts to Aquatic Habitat
will decrease the magnitude and frequency of high
flows and associated velocities, thus reducing
disruptions in migrations.
During operation of Watana dam, approximately 80
percent of the sediment 1 oad upstream of Watana
will settle out in the reservoir and be trapped
behind the dam. Sediments 1 ess than 3 to 4-
micron in diameter (20 percent of the sediment
load) will pass through the dam and be trans-
ported downstream to Cook Inlet.
Decreased sediment load combined with post-
project flow reductions will result in decreased
open-water turbidity downstream of Watana. The
relatively clear water will scour silts and sand
from the substrate downstream from the dam and
transport them down river. Over time, this will
result in the removal of fine sediments from the
streambed. However, much of the riverbed above
Talkeetna is presently armored with large gravels
and cobbles and s i 1 ts probably wi 11 be removed
only from the surface of the streambed. De-
creased sediment load is also expected to improve
benthic production, since siltation of intersti-
tial spaces will be reduced and light penetration
will increase. At present, high flows may limit
benthic production in the mai nstem as frequent
bed movement may preclude the develop.nent of a
stable environment.
The combination of impacts discussed above are
expected to produce the following changes to
spawning and rearing habitats during the open-
water season of Watana operation.
Small, isolated spawning areas located on the
river margins behind velocity barriers may be
degraded or dewatered. The creation of new
spawning habitat be natural process appears
unlikely. Although adequate depth and veloci-
ties are likely to exist, the lack of suitable
substrate would probably limit spawning in
this type of habitat. The streambed of most
of the mai nstem channel is composed of 1 arge
cobbles and boulders (R&M Consultants 198lc).
Even though flood flows would no longer flush
gravels from this reach, the recruitment of
gravel to the river will be limited because of
E-3-11 0
r
I
I
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r
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2.3 -Anticipated Impacts to Aquatic Habitat
sediment trapping in the reservoir. Isolated
deposits of gravel will occur downstream from
tributary mouths and may provide some suitable
spawning habitat.
Rearing habitat in the mainstem is expected to
increase under post-project conditions.
Reduced velocities and turbidity will probably
benefit young fish and resident adults. Areas
providing suitable habitat will likely still
be 1 imi ted to river margins or other 1 ow-
velocity areas created by obstructions in the
channel. Increased benthic production would
also enhance rearing habitats by providing
increased avai 1 abi 1 ity of prey items. Some
fish presently use the turbidity as cover,
thus increased clarity may result in greater
predation on small fish. With increased water
clarity, additional sport fishing may be
imposed on the fish in this reach of the
River •
• Winter/Ice Season
During the winter (October through April), main-
stem habitats are used by rearing salmon and
resident fish, including rainbow trout, burbot,
whitefish, and longnose sucker. Fish move out of
the tributaries to mainstem habitats where most
overwintering occurs (ADF&G 1981d, 1981e). The
impacts of Watana operation on these mainstem
habitats include,
Increased water temperature leading to a
change in ice cover;
Increased winter flows varying from 38 percent
·in October to 650 percent in February; and
Increased turbidity.
Winter thermal characteristics of the reservoir
determine the outflow temperatures and directly
influence downstream water temperatures. The
outflow from the Watana reservoir will 1 ikely be
about 4°C (39.2°F) at the beginning of winter,
cool quickly and remain about 1° {33.8°F) to 2°C
(35.6°F) throughout the remainder of the winter
(Chapter 2, Section 4.1.3[c][i]). Temperatures
E-3-111 .
2.3 -Anticipated Impacts to Aquatic Habitat
such as these would preclude development of an
ice cover in the upper section of this reach,
thus eliminating the associated staging and
backwater effect. Ice front progression above
the confluence is expected to start in late
December or early January with the upstream edge
of the ice cover progressing to between Sherman
(RM 130) and Portage Creek (RM 149) (Chapter 2,
Section 4.1.3(c)[ii]). Assuming reservoir
outflow temperatures decrease 1 i nearly from 4 oC
(39.2°F) on October 15 to 1oC (33.8°F) on January
1, an ice cover wi 11 form at RM 149. If the
outflow temperatures are constant at 4°C
(39.2oF), an ice cover wi 11 form by RM 130
(Chapter 2, Section 4.1.3(c)[ii]). Downstream
from the upper end of the ice cover, winter water
temperatures are expected to differ little from
pre-project conditions.
Because backwater and staging effects wi 11 be
eliminated in the post-project, open-water reach,
the river in this reach is expected to have
higher velocities, less depth and less wetted
perimeter than under pre-project condition with
an ice cover (Section 2.3.1(c)[ii]). In those
areas that retain an ice cover, wetted peri meter
and depth wi 11 greatly increase in many mainstem
habit at s because of staging and increased di s-
charge, although high velocities in several steep
gradient sections may prevent the formation of an
ice cover in these areas. Staging wi 11 occur at
the ice front, and if the stage of the river is
raised sufficiently, mainstem waters will flood
side-channels and sloughs.
Turbidity is projected to increase slightly over
present winter conditions. Particles less than 3
to 4 microns will remain in suspension in the
reservoir, increasing downstream turbidity levels
(Chapter 2, Section 4.1.3(c)[iv]). This slight
increase in turbidity is not expected to adverse-
ly affect fish populations using mainstem habi-
t at s. Fi sh apparently successfully overwinter in
habitats with similar levels of turbidity in the
Kenai River, Alaska (Burger et al. 1982). In-
creased post-project winter flows, warmer water
temperatures, and altered ice processes may have
the following impacts on fish in the Talkeetna to
Watana reach.
E-3-112
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2.3 -Anticipated Impacts to Aquatic Habitat
Increased flows will provide more under-ice
overwintering habitat for juvenile anadromous
and resident fish by increasing depth and
wetted perimeter •
•• Warmer water temperatures are expected to
benefit overwintering fish by reducing mor-
talities associated with freezing. Stream
temperature and discharge wi 11 remain fairly
stable, preventing fish from becoming trapped
in unfavorable areas that freeze. During the
winter of 1981-1982, information on fish dis-
tribution suggested that fish were seeking
warmer water temperatures. Bustard and Narver
(1975) reported that juvenile coho move to
warmer water for overwintering when warmer
water is available.
If the increased surface water temperatures
cause an increase in i ntergravel water tem-
peratures (i.e., the intergravel temperature
is not controlled by upwelling ground water),
then incubating embryos will be affected.
Incubation rates of fish embryos and benthic
invertebrates are closely tied to water tem-
peratures. An increase in i ntergravel water
temperatures would likely accelerate develop-
ment and resu 1t in early emergence. Early
emergence has been related to decreased sur-
vival rates in both benthic invertebrtates and
Pacific salmon (Bailey et al. 1974). Pink
salmon would be especially vulnerable to mor-
tality related to early emergence, since they
tend to select areas directly influenced by
surface water and tend to out-migrate shortly
after emergence. Young fish may begin to
out-migrate before downstream conditions are
suitable. Temperatures below the confluence
of the Chulitna River are 1 i kely to be near
0°C (32°F). Cllt-migrants encountering these
temperatures may experience thermal shock,
which has been linked to increased mortality
(Brett and Alderdice 1958 and Brett 1952).
Chum salmon would be less susceptible to
changes in surface water temperatures as the
adu 1 ts tend to se 1 ect areas influenced by up-
well ing ground water, which is buffered from
changes in mainstem surface water. In addi-
tion, chum salmon may rear for approximately a
E-3-ll3
2.3 -Anticipated Impacts to Aquatic Habitat
month before moving downstream. Early emer-
gency should have little effect on coho sal-
mon, since they remain in freshwater habitats
for two years and have been found to seek out
wanner areas in the spring. U.S. Fish and
Wildlife is currently studying the effects of
projected water temperature changes on incuba-
tion of Susitna River sockeye and chum salmon
eggs. The four temperature regimes under
study were chosen to provide an analysis of
probable post-project temperature variations
on incubation times as compared to pre-project
mainstem and slough water temperatures.
Other than the turbidity and temperature changes
discussed above, no impacts to water quality
parameters are anticipated under winter or open-
water conditions under Watana operation. Gas
supersaturation, which is caused by water passing
over a high spillway into a deep plunge pool and
dissolving air into the water, will not be a pro-
blem at Watana. Mitigation through the use of
cone valves in the spillway design is discussed
in Section 2.4.4(d).
-Side-Channel Habitats
Many of the project-induced physical changes iden-
tified for mainstem habitats would also occur in
side-channel habitats. Reductions from pre-project
streamflow during the open-water season may dewater
some spawning habitat presently used by salmon.
The lower operational flows during the spawning
season may concentrate spawning salmon in areas
that are less likely to dewater under the higher
winter flows' and thus increase spawning success.
Side channels with lower streambed elevations are
presently subject to scouring at high flows and
many do not have substrates suitable for spawning.
Most are armored with 1 arge cobbles and boulders
that are underlain with large gravels embedded in
silt and sand.
Operational flow should result in additional rear-
ing areas becoming available in side-channel habi-
tats during the open-water season. Lower dis-
charges generally result in decreased velocities
and depths. This would likely improve the quality
of these areas as rearing habitat for some resident
and juvenile anadromous fish.
E-3-114
2.3 -Anticipated Impacts to Aquatic Habitat
Post-project water temperatures in the side-channel
areas will be similar to mainstem water tempera-
tures, since mainstem water is the controlling
factor. However, temperatures of water in 1 ateral
margins of the side channels may be slightly warmer
than mai nstem water because of shallower depths,
slower velocities, and increased water clarity.
Increased water temperatures may enhance the
quality of rearing habitat in the side-channels
(Abbad 1980; Clarke et al. 1981).
The approximate tenfold decrease in turbidity dur-
ing the open water season will likely have a bene-
ficial effect effect on food production in side-
channel habitats. More energy would be avail able
for primary production, thus increasing the food
base for other trophic levels. The post-project
flow will be carrying a lower sediment load and may
also remove many of the silts and sands presently
occupying the interstitial spaces of the substrate.
This is expected to provide more habitat for ben-
thic invertebrates.
During the late fall and winter period, mainstem
discharges at Gold Creek will increase approxi-
mately 40 to 655 percent over pre-project flows
(Table E. 3. 32). The magnitude of the increase in
flow expected to occur in side-channel habitats is
dependent on the stage in the mai nstem and the
streambed elevation of the upper end of the side-
channels. Presently, the stages in the side-
channels drop in the fall as mai nstem flows
decrease. As the river forms an ice cover, the
side-channel stages increase because of the back-
water effects caused by ice formation. During
operation of Watana dam, the flow at Gold Creek
will not drop significantly below 7700 cfs in the
fall or winter period. Wetted perimeter, depth,
and velocities are expected to increase in side-
channels during the winter months. Side channels
will be less susceptible to dewatering and freezing
under the higher post-project winter flows than at
present.
Incubation success in side-channel areas may
imp rove under post-project conditions as the eggs
will be less 1 ikely to dewater. Increased flows
are expected to a 1 so provide greater i ntergravel
flow, which would benefit incubating embryos and
alevins. The increased post-project winter flows
E-3-115
2.3 -Anticipated Impacts to Aquatic Habitat
would also increase the availability of over-
wintering habitat for juvenile anadromous and
resident fish in side-channel habitats by pro-
viding more living space and being less likely to
freeze during the winter.
-Slough Habitats
During the open-water season, impacts to slough
habitats above Talkeetna under operation of
Watana dam are not expected to substantially dif-
fer from those resulting from filling the Watana
reservoir. Streamflows during late fall, winter,
and early spring will be increased, providing a
higher stage in the mainstem. The increased
stage is expected to increase the rate and areal
extent of ground water upwelling in the sloughs
and the potential for overtopping the upstream
end of the slough causing flow through the slough
and flooding. Incubation success of salmon
embryos may be improved because of the increased
ground water flow.
Post-project winter conditions may affect incuba-
tion and overwintering in the sloughs. The in-
creased flows in conjunction with increased water
temperatures will change the ice processes in
this reach of river. Presently, as the mainstem
forms an ice cover, the stage increases because
of backwater effects. These staging effects were
measured near Gold Creek between RM 135 and RM
138 on December 12, 1980 (R&M Consultants 1982d).
The mainstem discharge was 1800 cfs. At 11:30
a.m., the stage at the leading edge of ice
corresponded to a discharge of 19,000-29,000 cfs.
By 2:00 p.m., the ice edge had advanced upstream
about 2300 feet (690 m); the under-ice stage 5900
feet (1787 m) downstream from the edge was
representative of a flow of 23,400 cfs. Under
post-project conditions, the river is expected to
form an ice cover up to RM 130 and, depending on
meterological conditions, the ice cover may
extend up to RM 149. Thus, the stage in the
river and the wetted perimeter of sloughs and
side channels would probably decrease relative to
pre-project winter conditions upstream from the
ice front. If the decrease in wetted perimeter
and water depth results in dewatering or
increased depth of freeze, eggs incubating in the
gravels could be adversely affected. Overwinter-
; ng areas may also be adversely affected by the
E-3-116
r-,
('
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,_.
I
I
....
Z.3 -Anticipated Impacts to Aquatic Habitat
(iii)
same physical processes '':ausing ·increased
mortalities for juvenile anadromous and resident
fish.
In sloughs at and downstream from the ice cover
front, the post-project mainstem flow could overtop
the head ends of the sloughs. The addition of near-
freezing mainstem water would reduce the surface
water temperatures of the sloughs and increase the
formation of ice. In some cases, considerable
icing could occur; and the value of these areas for
overwintering would be reduced.
The ice wou 1 d reduce surface water temperatures in
the sloughs well into the spring. Since the mech~
anical"breakup 1 ikely would not occur, these ice
formations in the sloughs would melt out rather
than being carried out by high flows. Ice may be
present in the sloughs until late June. The
presence of ice would reduce the surface water tem-
peratures and may alter the quality of these areas
as early nursery areas for emerging fry.
-Tributary Habitats
Tributary habitats in the Watana d~m to Talkeetna
reach would be affected similarly under both fil-
ling and operation during the open-water season.
Augmented winter flows wi 11 increase the amount of
overwintering habitat associated with tributary
mouths, since higher discharge in the mainstem will
increase the water depth and extent of backwaters
at the tributary mouths. Studies indicate that
tributary mouths are important overwintering habi-
tat (ADF&G 198ld, 1981e).
Talkeetna to Cook Inlet
Project effects in this reach of river are expected
to be considerably reduced in magnitude from those
presented for the Watana dam to Talkeetna reach
because of the influence of the Chulitna and
Talkeetna Rivers. Many of the changes identified
under the filling schedule (Section 2.3) for the
open-water season wi 11 be the same under o per at ion
flows. Winter flows will be increased.
E-3-117
2.3 -Anticipated Impacts to Aquatic Habitat
-Mainstem Habitats
During the open-water season, mainstem habitats
will be similarly affected during f"illing of the
Watana reservoir and operation of Watana dam.
Operational flows during this period are slightly
greater than filling flows in the late spring and
early fall and nearly equal to filling flows duriny
summer months (Tables E.3.29, E.3.30, E.3.33, and
E. 3. 34) 0
Bering cisco spawned in mainstem habitats during
October 1981 and 1982. Si nee 1 ittle change in
average monthly streamflow or in stream temperature
is anticipated during October, these fish are not
expected to be adversely affected by the project.
In the Susitna River, eulachon spawn mainly below
the Yentna River in mainstem habitats. Eulachon
spawning areas identified during spawning surveys
in May 1982 were located in relatively shallow
water adjacent to cut banks and in riffle cones or
bars with moderate velocities (ADF&G 1983). These
habitats would probably exist to the same extent in
this portion of the river under post-project condi-
tions as during pre-project conditions. This seg-
ment would be subjected to the 1 east amount of
change, since it is buffered by inflow from all
major tributaries below Talkeetna. Reductions in
average monthly streamflow of 10 to 26 percent at
Sunshine (pre-project flows of 27,700-64,500 cfs to
operational flows of 24,900-48,300 cfs) and 5 to 13
percent at Susitna (pre-project flows of 60,800-
132,400 cfs to operational flows of 57,900-117,400
cfs) are predicted from May through September
(Tables E.3.33 and E.3.34).
During the winter (October through April), in-
creases in average monthly discharges of 17 to 277
percent at Sunshine (pre-project flows of 2600-
13,800 cfs to operational flows of 9500-16,100 cfs)
and 18 to 114 percent at Susitna (pre-project fows
of 6300-30,400 cfs to operational flows of 13,300-
32,700 cfs) are predicted (Tables E.3.33 and
E.3.34). Water temperatures are not expected to
differ from pre-project conditions. Increases in
discharge will result in increases in wetter peri-
meter.
E-3-118
-
2.3 -Anticipated Impacts to Aquatic Habitat
The availability of overwinter-ing habitat is
expected to increase bee au se of increased water
depth and wetter perimeter. Si nee the flow wi 11
remain fairly constant, increased fish and embryo
survival may result from reduction of mortality
associated with freezing.
-Side-Channel Habitats
As discussed under the reservoir filling flow
regime, reductions in streamflow during the open-
water season may dewater or degrade some spawning
habitat presently used by salmon, as well as affect
rearing and summer feeding habitat for residents
and anadromous juveniles.
During the winter period, st reamfl ows in side-
channel habitats will be increased because of the
increased winter discharge (Tables E.3.33 and
E.3.34). These increased winter discharges are
expected to have a beneficial effect on overwinter-
ing fish and incubating embryos. Increased dis-
charge will increase depths in side-channel areas.
This will provide more living space and should pre-
vent dessication and freezing in these areas.
Increased surface flow may also result in increased
·intergravel flow, which would benefit embryo devel-
opnent and overwintering juveniles.
-Slough Habitats
Increases in winter st reamfl ows are expected to
have a beneficial effect on slough habitats. The
augmented discharge will increase the areal extent
of the backwater at the slough mouth, creating
greater water depth within the slough. The up-
stream extent of the backwater effect wi 11 depend
on the gradient of the slough. Increased water
depth may prevent a portion of the slough from
freezing and incr.ease the availability of over-
wintering habitat.
-Tributary Habitats
Tributary mouths are expected to be affected Slml-
larly under both filling and operation of Watana
dam during the open water season. llrring the win-
ter, tributary mouths provide important overwinter-
·ing habitat. The effects of higher discharge :in
2.3 -Anticipated Impacts to Aquatic Habitat
the mainstem should increase the areal extent of
the backwaters and increase the amount of
overwintering habitat associated with tributary
mouths.
(ii) Estuary Habitats
Si nee only minor changes in salinity are predicted
under project operation (Chapter 2, Section 4.1.3
[f][iii]), no impacts to fish resources in the
estuary are anticipated.
(d) Summary of Impacts Associated with Watana Dam
(i) Construction Impacts
The primary long-term aquatic impact related to con-
struction of Watana dam will be the increase in har-
vest pressure resulting from the inc rea sed access
afforded by the project roads. In the absence of
stricter harvest regulations, the increase in access
near the impoundments will cause substantial altera-
tions in resident fish population structure, with the
present population of large, long-lived grayling
being replaced by younger individuals.
There will be degradation of aquatic habitat at
stream crossings but with proper construction prac-
tices as discussed in Section 2.4.3, this impact is
not expected to noticeably affect fish populations.
Construction activities and reservoir clearing acti-
vities will cause temporary increases in siltation
and turbidity in some of the project area clear-water
streams. These impacts are not expected to extend
beyond the construction period. Simi 1 arly, a ltera-
tions in water quality and disturbance to fish popu-
lations are expected to impact fish only during the
construction period. There will be a continuous
possibility of fuel spills during the construction
period when numerous construction vehicles are pre-
sent in the project area. The possibility of acute
spills will be reduced under operation, but chronic
spills will occur for the life of the project. Acute
spills could cause locally significant impacts to
fish populations, while chronic spills will cause
gradual habitat degradation, particularly along
roadways.
E-3-120
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2.3 -Anticipated Impacts on Aquatic Habitat
The borrow site at the mouth of Tsusena Creek will
create aquatic habitat at the expense of riparian
habitat. This new aquatic habitat is expected to
provide productive feeding and overwintering habitat
for fish.
(ii) Filling Impacts
Impacts associated with the three years needed to
fill the Watana reservoir are divided into impound-
ment impacts and downstream impacts.
The primary long-term impact associated with the fil-
ling of the Watana reservoir is the loss of clear
water tributary habitat. The tributary habitat that
will be inundated currently supports a substantial
population of grayling, estimated to be at least
15,100 in 1982 {Table E.3.17). Aquatic habitats
within the reservoir are not expected to support a
significant grayling population {Section
2.3.1(b)[i]).
Between Watana dam and Talkeetna, the primary impacts
associated with filling will be a reduction in spring
and summer flows, reduction in sediments, and altered
temperature regime, particularly during the second
year of filling. Mainstem and side-channel habitats
will contain less turbid water and be-subjected to
less extreme fluctuation in water levels and flow
during the summer. These changes are expected to
provide more favorable fish habitat than now exists
in these areas. During the second year of filling,
4°C {39.2°F) water will be released at the dam; this
is expected to warm to 5° to 6°C (41° to 42.8°F) at
Talkeetna. The adult salmon migration into the
Watana dam to Talkeetna reach may be delayed, and
some of the returning adults, particularly pink and
coho salmon, may select alternative spawning areas
because of the lower summer temperatures. This
impact is expected to be confined to the second year
of filling and have no long-term impacts on popula-
tion levels. The decreased temperature is expected
to decrease the growth of resident and juvenile
anadromous fish for the one summer, but significant
impacts to the populations are not expected (see
Section 2.3.1{b)[ii]).
Slough habitats between Watana dam and Talkeetna are
expected to be the habitat type most significantly by
filling flows. In the absence of mitigation fea-
tures, filling flows are expected to cause access
E-3-121
2.3 -Anticipated Impacts to Aquatic Habitat
problems for returning adult chum and sockeye salmon.
For salmon that do gain access, the spawning area
within the sloughs may be reduced in area because of
the lower mainstem flows (see Section 2.3.1(b)[ii]).
If un-mitigated, these impacts would reduce the
number of spawning chum and sockeye salmon in the
sloughs above Talkeetna. Under a worst case scenario
in which all slough spawning is lost, the total run
to the Susitna River would be reduced by an estimated
11,840 chum; 9200 sockeye, and 3550 pink salmon based
on 1981 and 1982 escapement data (see Section
2.3.2(b)[ii] Slough Habitat). The sockeye spawning
in sloughs upstream from Talkeetna are considered to
be strays from Chulitna and Talkeetna stocks (ADF&G
1983), thus there may be no production from these
adults. If this is true, there would be no loss of
sockeye to the fishery.
Tributary habitats bel ow Watana dam and all habitats
below Talkeetna are not expected to be significantly
impacted during the fi 11 i ng of the Watana reservoir
(Section 2.3.1(b)[ii] and [iii]).
(iii) Operation Impacts
Operation impacts, as with filling, are divided into
impacts due to the impoundment and downstream
impacts.
The habitat within the reservoir is not expected to
support substantial fish populations (Section 2.3.1
(c)[i]). The annual drawdown cycle will limit spawn-
; ng habitat of grayling, 1 ake trout, bur bot, white
fish and 1 ongnose sucker. Littoral rearing habitat
is also not expected to be productive because of the
drawdown cycle and summer turbidity levels. Grayling
are expected to reside at the mouths of the tribu-
taries. Lake trout and Dolly Varden are expected to
develop reproducing populations within the reservoir.
Other species are expected to migrate into the reser-
voir from upstream habitats, primarily to overwinter,
and may residualize.
Between Watana dam and Talkeetna, the primary opera-
tional impacts will be similar to those discussed for
filling: decreased summer flows, decreased flow vari-
ability and decreased sediment load. During winter,
however, flows will increase over pre-project condi-
tions and will be accompanied by increased tempera-
ture and turbidity.
E-3-122
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2.3 -Anticipated Impacts to Aquatic Habitat
More stable summer flows and decreased turbidity are
expected to improve rearing habitat in mai nstem and
side-channel habitats. Eventually, mainstem and
side-channel spawning habitats are expected to become
available, as the less turbid water removes intersti-
tial silt from the presently cemented substrate
(Section 2.3.1(c)[ii]).
The decreased summer flows, however, will likely
cause passage problems for adult salmon entering
slough spawning habitats, as was discussed under
filling impacts. Similarly, spawning habitat within
the sloughs will likely be reduced, since the area of
ground water upwelling may be reduced with 1 ower
mainstem flows (Section 2.3.1(c) [ii]). If unmitiga-
ted, these impacts will reduce the number of chum and
sockeye salmon spawning in the sloughs upstream from
Talkeetna. The worst case scenario would be total
loss of slough spawning habitat in this reach, with a
reduction in the total run size, as discussed in the
previous section (Section 2.3.1{d)[ii]).
The increase in winter flow is expected to increase
overwintering habitat and will benefit resident and
rearing anadromous species. The reduction of flow
variability, peak flows, turbidity, and sediment load
in the mainstem during summer combined with increased
winter flow, may lead to increases in the populations
of some resident species, such as rainbow trout and
Dolly Varben, and rearing anadromous species, such as
chinook and coho salmon. The amount of increase, if
any, will depend on the extent to which these physi-
cal factors presently limit the populations.
The increased winter temperatures may increase embryo
development in mainstem and side-channel spawning
habitats and lead to early emergence of alevins.
These early emerging fry are expected to experience
increased mortality if they move downstream and
encounter 0°C (32°F) 1 water below Talkeetna. This
impact will likely affect relatively few fish, pri-
marily pink salmon, since only a small portion of the
salmon spawning upstream from Talkeetna utilize main-
stem and side-channel spawning habitats. Other sal-
mon species using these habitats exhibit behavior
patterns that reduce their vulnerability to these
impacts (Section 2.3.1(c)[ii]). Impacts are not
expected in tributary habitats upstream from
Ta ·1 keetna.
E-3-123
2.3-Anticipated Impacts to Aquatic Habitat
Downstream from Talkeetna the main impact will be an
increase in overwintering habitat in the mainstem and
side channels because of the increased winter flows
(Section 2.3.1(c)[iii]). No significant adverse
impacts are expected.
2.3.2 -Anticipated Impacts to Aquatic Habitat
Associated with Devil Canyon Dam
Impacts sustained by aquatic habitats as a result of construction
and operation of Devil Canyon dam will be similar to those occur-
ring under construction and operation of Watana dam. This sec-
tion addresses additional impacts and increased magnitude of
impacts to aquatic habitats attributable to the development of
Devil Canyon dam, assuming Watana dam is in place.
(a) Construction of Devil Canyon Dam and Related Facilities
(i) Devil Canyon Dam
Devil Canyon dam will be 1 ocated at RM 152 of the
Susitna River, approximately 32 miles (53 km) down-
stream from the Watana damsite. A concrete arch thin
dam will be built at the downstream end of Devil
Canyon and an earth/rockfi 11 saddle dam wi 11 be con-
structed at the south end of the arch dam to provide
closure of a low area at the south abutment. The
reservoir behind Devil Canyon will cover 7800 acres
(3120 ha) and will be about 32 miles (53 km) long and
not more than 0.5 mile (0.8 km) wide (Figure
E.3.23).
The concrete dam and foundation wi 11 be 646 feet
( 195 m) high and wi 11 have a crest 1 ength of 1650
feet (500 m)j An estimated 2. 7 mill ion cubic yards
(2,052,000 m ) of concrete will be needed to con-
struct the arch dam. The saddle dam wi 11 be 950 feet
(287 m) across and 245 feet (74 m) high and wi 11
require about 1.2 million cubic yards (912,000 m)
of materia 1.
As with Watana, Devil Canyon dam will have an under-
ground powerhouse, intake structure, outlet works,
main and emergency spillway. A 39-foot (11.8-m)
diameter tailrace tunnel will convey the turbine
discharge approximately 1.3 miles (2.2 km) downstream
from the arch dam.
E-3-124
r--,,
2.3-Anticipated Impacts to Aquatic Habitat
During construction of the dam, the river will be
blocked above and below the construction site by
cofferdams. The flow will be diverted into a
30-foot (9-m) diameter horseshoe tu n_nel, 1490 feet
(451 m) long, and discharged back into the river
channel. The upstream and downstream cofferdams will
be about 400 feet ( 120 m) 1 ong and 200 to 400 feet
(60 to 120 m) wide.
The adverse impacts upon aquatic habitat at the Devil
Canyon damsite are expected to be similar to those at
the Watana site but of lesser magnitude.
At the Devil Canyon damsite, the Susitna River is
confined to a canyon approximately 600 feet (180 m)
deep and 200 to 400 feet (60 to 120 m) wide at river
1 evel. The river bottom is primarily composed of
cobbles, boulders, and blocks of rock; the water is.
extremely' 'turbulent. It is expected that few fish
live in the area of the damsite (ADF&G 1981e). Some
chinook salmon migrated upstream from the Devil
Canyon damsite during the 1 ow summer flows of 1982
(ADF&G 1982e) and are expected to pass through the
canyon during the low spring flows associated with
operation of Watana dam.
-Alteration of Waterbodies
Impacts from Devil Canyon Dam construction will be
primarily restricted to the vicinity of the dam-
site. A 1100-foot (333-m) section of the Susitna
River between the cofferdams wi 11 be dewatered for
7 years during construction. Although a small pop-
ulation of Dolly Varden·and at least one sculpin
species as well as possibly other resident species
inhabit that stretch of river, it is not expected
that dewatering will have more than a minor impact
upon availability of suitable aquatic habitat. The
dam foundation wi 11 cover about 90 feet (27 m) of
river bottom. This is considered to be a minor
impact.
Construction of the arch dam and the saddle dam
will require excavation in the river channel at the
damsite. Excavation by blasting or by mechanical
means may result in the introduction of materials
into the Susitna River that would be carried down-
stream. The turbulence of the water at the site
E-3-125
2.3-Anticipated Impacts to Aquatic Habitat
would preclude sedimentation in that stretch of
river. Adverse impacts from introduction of
increased sediment are expected to be minor.
The greatest impacts during construction of the dam
are likely to be associated with gravel mining and
processing in Borrow Site G. Gravel for filter
material and for concrete aggregate will be removed
from the Susitna River and from Cheechako Creek
alluvial areas upstream from the damsite (Borrow
Site G). The effects of gravel mining on aquatic
systems have been discussed under Section 2.3.l(a).
Since the material removal sites will be inundated,
impacts at the sites will be transitory.
Changes in Water Quality
Potential impacts to water quality waul d primarily
be caused by increases of turbidity due to erosion
and through discharge of effluent from the concrete
batching process. To minimize water quality im-
pacts, a 11 process waters wi 11 be treated before
being discharged to the Susitna River. Turbidity
increases in the Susitna River are expected to be
neglible. See Section 2.3.l(a) for discussion.
-Disturbance of Fish Populations
Instream activities during material extraction near
Cheechako Creek could disrupt fish movements,
spawning, and rearing in the creek, depending upon
location, type and duration of activities. It is
unlikely that the damsite itself is located in a
stretch of the Susitna regularly inhabited by fish;
therefore, it is expected that the excavation and
blasting required at the damsite would not be dis-
ruptive to fish populations.
(ii) Construction and Operation of
Devil Canyon Camp and Village
During construction of Devil Canyon dam, housing will
be constructed for 1900 persons (Chapter 3, Section
3.3.1[d]). The construction camp and construction
village will be located between 1.7 and 3.4 miles
(2.8 and 5.6 km) southwest of the damsite. The camp
will include bachelor dormitories, cafeteria, ware-
houses, offices, hospital, and recreational build-
ings. The village will contain housing for 170 fami-
1 i es and wi 11 inc 1 ude a schoo 1 , stores, and a recrea-
tion area.
E-3-126
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2.3 -Anticipated Impacts to Aquatic Habitat
The camp will be approximately 0.5 mile (0.8 km) from
the village. Both developments will be more than 700
feet (210 m) above the Su sitna River and more than
4000 feet ( 1200 m) from the edge of the canyon.
Water, sewage, and solid waste disposal facilities
wi 11 be shared by both developments. Water wi 11 be
withdrawn from the Susitna River and effluent from a
secondary treatment system discharged into the river
bel ow the water intake. The upper reaches of Jack
Long Creek border the camp and the vi 11 age to the
south, coming to within 200 feet {60 m) of the camp.
A small unnamed creek drains a series of lakes 3000
feet {900 m) to the east of the camp and enters the
Susitna at RM 150. The creek is paralleled by the
sewage outfall 1 i ne for 1000 feet {300 m) or about 20
percent of its 1 ength. ·
Both the camps and the village are temporary develop-
ments to be removed when De vi 1 Canyon construction is
completed. Permanent personnel responsible for
operations of the Devil Canyon dam will 1 ive at the
Watana permanent town. No airstrip wi 11 be bu i 1 t;
air access wi 11 be vi a the permanent runway at
Watana.
The unnamed creek and 1 akes may support grayling.
Jack Long Creek contains pink, chi nook, chum, and
coho salmon (Figure E.3.17). Portage Creek contains
chum, pink, chinook, and coho salmon, rainbow trout,
round whitefish, and humpback whitefish. Chinook
salmon, grayling, and Dolly Varden are found in the
1 ower reaches of Cheechako Creek. Temporary impacts
resulting from camp/village operations are expected
to be limited to the area within a few miles of the
dams it e.
-Alteration of Waterbodies
No water bodies are expected to be alterated as a
result of Devil Canyon camp construction other than
those resulting from gravel mining within the
Su sitna River fl oodpl ai n at Borrow Site G. Si nee
this site will eventually be inundated, no
permanent effects of gravel mining will occur.
Camp construction is not anticipated to affect Jack
Long Creek or the unnamed stream.
E-3-127
2.3 -Anticipated Impacts to Aquatic Habitat
-Changes in Water Quality
Erosion into the Susitna River from gravel m1n1ng
at the mouth of Cheechako Creek is not expected to
result in adverse impacts to fish. Because of its
proximity to the developments, Jack Long Creek may
receive uncontrolled runoff from the camp area.
However, required drainage facilities and retention
ponds should eliminate this impact and increased
sediment 1 evel s shou 1 d not adversely affect spawn-
ing habitats in Jack Long Creek.
Water for camp use will be withdrawn from the
Susitna River, and treated effluent and wastewater
will be returned to the river. The treated efflu-
ent will not affect the waste assimilative capacity
of the Susitna and is expected to have no signifi-
cant effect on the aquatic environment (Chapter 2,
Section 3.3.1 [d]). Storm drainage and oily water
runoff from the construction camp will be collected
and treated as noted above.
The fuel storage area is located on the south side
of the construction camp about 200 feet (60 m)
above Jack Long Creek. Accidental fuel spills
could reach the creek if storage facilities failed.
It is not expected that runoff from the solid waste
disposal site and the construction village will
adversely affect any waterbodies, since both will
be collected and treated the same as the runoff
from the camp area.
-Direct Construction Activity
The camp and village at the Devil Canyon site will
house 1900 workers for several years (Chapter 2,
Section 3.3.1[d]). It is expected that, as a
result, streams and lakes in the vicinity will be
subjected to increased fishing pressure. This area
has not been heavily utilized for sport fishing in
the past.
The waterbodies most likely to be affected include
Cheechako Creek, unnamed creeks and 1 akes, Jack
Long Creek, and to a 1 esser extent, the Su sitna
River and Portage Creek. With the exception of
Portage Creek, these waterbodies are within walking
distance of the camp/village and the damsite.
E-3-128
p.--,
P""'
i
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2.3 -Anticipated Impacts to Aquatic Habitat
(b)
Portage Creek enters the Su sitna River from ·the
north about 2.5 miles (4.1 km) downstream from the
dam location on the opposite side of the Susitna
River.
Filling Dev-il Canyon Reservoir
The filling of the Devil Canyon reservoir will be done in
two stages. Upon completion of the dam to a height suffi-
cient to allow pending above the lowlevel outlet facilities,
the water level will be raised to an elevation above 1050
feet (315m) but not exceeding 1135 feet (343m). This
filling will be accomplished in approximately 4 weeks. As
soon as the power facilities and main spillway are comple-
ted (approximately one year or more), the reservoir will be
raised to 1455 feet (440 m), the normal operation elevation,
in 5 to 8 weeks. During filling of Devil Canyon, the down-
stream flows at Gold Creek will not drop below the project
operational minimum flows.
(i) Inundation of Upstream Habitats
Filling Devil Canyon reservoir would inundate approx-
imately 32 miles (53 km) of Susitna River mainstem
habitat and 11 miles ( 18 km) of tributary habitats.
These habitats would be converted from lotic to len-
tic systems with accompanying changes in hydraulic
characteristics, substrate, turbidity, temperature,
and nutrient levels (Chapter 2, Section 3.4.2[c]).
These changes are expected to result in a shift in
species composition. The area presently supports
arctic grayling, burbot, longnose sucker, whitefish,.
and Dolly Varden (ADF&G 1981f). Impacts to mainstem
habitats are expected to be similar to those presen-
ted in Section 2.3.l(b) for Watana Reservoir. The
loss of clear-water tributary habitat in Tsusena and
Fog Creeks will eliminate habitat utilized by approx-
imately 1200 grayling 1 anger than 8 inches (20 em)
(Table E.3.17). Effects on tributaries and associ-
ated fish are also expected to be similar to those
presented for the Watana Reservoir. Most of the tri-
butaries in the Devi 1 Canyon impoundment area are
c ha racteri zed by steep s 1 opes with occasion a 1 bar-
riers, such as waterfalls. Cheechako, Devil and
Tsusena Creeks, three tributaries entering the Devil
Canyon impoundment, all contain waterfalls. These
falls will not be inundated by the impoundment and
would still function as barriers to fish passage.
E-3-129
2.3 -Anticipated Impacts to Aquatic Habitat
The four tributaries that are expected to support
chi nook spawning during fi 11 i ng and o per at ion of the
Watana dam wi 11 be 1 ost as chi nook habitat after
Devil Canyon dam is in place.
(c) Operation of Devil Canyon Dam
Post-project streamflows under the operation of Devil Canyon
dam would be similar to those under the operation of Watana
dam alone. Most of the impacts to the aquatic habitat would
have occurred under the startup and operation of the Watana
dam.
Few additional impacts are expected to result from operation
of Devil Canyon during the open-water season. Changes in
streamflow are presented in Tables E.3.35, E.3.36, and
E.3.37.
(i) Reservoir Habitat
During operation of the Devil Canyon reservoir, the
water surface elevation will remain at 1455 feet
(440 m) above sea level from November through July,
except during an extreme drought. During August,
water will be released to maintain minimum downstream
flows for returning adult salmon. The water surface
elevation will normally decrease to 1405 feet (425 m)
until downstream flow requirements diminish in late
September. The water level will be returned to 1455
feet {440 m) by the end of October (Figure E.2.111).
The stable water level in Devil Canyon for most of
the year will create favorable spawning conditions
for most fish species. Arctic grayling, lake trout,
bu rbot, whitefish and 1 ongnose sucker spawning is
expected to be unaffected. Dolly Varden embryos that
are deposited in the drawdown zone of reservoir tri-
butaries during September and October may experience
a higher mortality than those deposited above the
draw-down zone. The impact to Dolly Varden popul a-
t ions in the reservoir is expected to be minor.
Productivity in the Devil Canyon reservoir is
expected to be low because of the turbidity levels
(Chapter 2, Section 3.4.2{c)(iii)), but should be
greater than the productivity in the Watana reservoir
because of the 1 ess extreme draw-down cycle. It is
expected that the Devil Canyon reservoir will develop
E-3-130
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2.3 -Anticipated Impacts to Aquatic Habitat
resident po!XJl at ions of 1 ake trout, Dolly Varden,
burbot, whitefish ~nd other species. Arctic grayling
will occur in and at the mouths of clear-water tribu-
taries.
(ii) Devil Canyon Dam to Talkeetna
-Mainstem Habitats
Flow in approximately 1.5 mile (2.5 km) of river
between the dam and the powerhouse outlet will be
eliminated. Depending on backwater effects, this
will result in a dry channel for approximately 3300
feet (1000 m) below Devil Canyon dam. The gradient
bel ow the dam is quite steep and the bed is com-
posed of coarse substrates. The area is presently
thought to provide marginal habitat for resident
fish.
As described in Section 2.3.1(c), use of mainstem
habitats may significantly change during operation
of the Watana dam. Downstream from the De vi 1
Canyon dam tailrace, however, there would likely be
little additional changes in mainstem habitat use
during the open-water season. Flow reductions in
July and August of 9 and 6 percent, as compared to
Watana alone, may slightly increase the magnitude
of effects identified under operation of Watana
dam.
Under operation of Devil Canyon dam, winter water
temperatures in the Devil Canyon to Talkeetna reach
wi 11 be increased. The ice front is expected to
form between Talkeetna (RM 99) and Sherman (RM
130}; thus, the staging and backwater affects asso-
ciated with an ice cover would not occur upstream
from RM 130 in this portion of the river (Chapter
2, Section 3.4.3[b]}. Winter temperatures in the
reach from Devi 1 Canyon to Ta 1 keetna are expected
to range from 0 to 1.5°C (32.0 to 34.JOF} during
the operation of the Watana dam. Outflow tempera-
ture from Devil Canyon dam will be 2 to 4°C (35.6
to 39.2°F), with downstream temperatures ranging
from 0 to 3°C (32 to 37.4°F). Although this is
only a slight increase over natural conditions, it
will often preclude an ice cover on most of the
river above Talkeetna. Impacts resulting from
altered ice conditions are discussed under
Operation of Watana Dam (Section 2.3.1(c)[ii]).
E-3-131
2.3 -Anticipated Impacts to Aquatic Habitat
-Side-Channel Habitats
Side-channel habitats are expected to sustain
impacts similar to those predicted for mainstem
habitats under operation of Devil Canyon dam.
Slough Habitats
The predicted streamflows during the open-water
season under operation of Devi 1 Canyon are not
expected to have significant affect on slough habi-
tats over those affects related to Watana operation
alone. The slough habitats will have had approxi-
mately nine years to adjust to the Watana opera-
tional flow r~gime during construction of the Devil
Canyon dam. Changes in flow at Gold Creek from
Watana alone to Watana and De vi 1 Canyon are 1 i sted
in Table E.3.35. During the open water season,
average monthly flows at Gold Creek will be reduced
by 16 and 13 percent in May and June, respectively;
and by 9 and 6 percent in July and August, respec-
tively. Average September flows at Gold Creek will
be 7 percent greater with the operation of both
dams and during October will be 3 percent 1 ess.
Thus, open-water season stream flow changes due to
the operation of Devil Canyon dam are not anticipa-
ted to be significant to the slough habitat. Al-
teration of the thermal regime during winter will
affect a greater number of sloughs than under op-
eration of Watana, but effects are expected to be
similar to those discussed in Section 2.3.1(c)
[ii]).
(iii) Talkeetna to Cook Inlet
No additional impacts are expected to occur in this
reach as a result of operation of Devil Canyon dam.
The physical changes to habitats downstream from
Talkeetna resulting from the operation of Watana dam
waul d 1 i kely remain the same when Devi 1 Canyon dam
commences operation." A comparison of proposed down-
stream flows for Watana dam alone and with the addi-
tion of Devil Canyon is presented for Sunshine Sta-
tion in Table E.3.36. Changes in streamflow range
from a reduction of 7 to an increase of 11 percent.
Changes in flow of this magnitude are not expected to
result in effects different from those identified
under the operation of Watana dam. The addition of
Devil Canyon is not expected to result in substantial
E-3-132
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2.3 -Anticipated Impacts to Aquatic Habitat
(d)
changes in water temperatures, water quality, or
sediment transport in this reach. Thus, the addition
of De vi 1 Canyon dam is not expected to result in
adverse effects on fishery resources associated with
habitats below Talkeetna.
(i v) Estuary
The operation of Devil Canyon dam is not expected to
impact the estuary. Physical changes occurring under
operation of Watana alone would essentially remain
the same under the operation of both dams.
Summary of Impacts Associated with
Devil Canyon Dam
(i) Construction Impacts
( i i )
As with Watana dam, the most significant long-term
impact associated with Devil Canyon dam will be the
increase in fishing pressure. Other impacts result-
ing from construction activities will be transitory
and are not expected to significantly affect fish
populations.
Reservoir Filling
Filling the Devil Canyon reservoir will inundate
portions of clear-water tributaries, two of which
( Tsusena and Fog Creeks) presently provide summer
habitat within the reaches to be inundated for
approximately 1200 grayling 1 anger than 8 inches
( 2 0 c m ) • Aq u at i c h a b i tat s i n t he res e r v o i r a re
expected to support more productive resident fish
populations than those in the Watana reservoir be-
cause of the timing and magnitude of the annual draw-
down cycle. The reservoir will be filled in approxi-
mately 5 to 8 weeks without impacting downstream
flows. Downstream impacts are not expected during
this period.
(iii) Operation Impacts
No s i gni fi cant impacts are expected upstream from
Devil Canyon dam. The reservoir is expected to
support populations of lake trout, Dolly Varden,
Arctic grayling, burbot, whitefish, and longnose
sucker.
E-3-133
2.3 -Anticipated Impacts to Aquatic Habitat
The most significant downstream impact resulting from
the addition of Devil Canyon dam will be the change
in winter water temperature, which will cause the ice
front to form between Talkeetna (RM 99) and Sherman
(RM 130) instead of between Sherman (RM 130) and
Portage Creek (RM 149} as with Watana alone. The
river stage in the open-water reach wi 11 be 1 ower
than the stage present under an ice cover. This
change will reduce available habitat in areas that
previously formed an ice cover, as was discussed for
impacts associated with Watana dam (Section
2.3.1{c)).
Additional impacts to habitats between Talkeetna and
Cook Inlet are not expected.
2.3.3 -Impacts Associated with Access
Roads, Site Roads, and Railroads
(a) Construction
{i) Construction of Watana Access
Road and Auxiliary Roads
The main access to the Watana damsite will be from
the Denali Highway (Alaska Power Authority 1982a).
The Watana access road will depart the Denali Highway
at Milepost 114 and will run 41.6 miles {69.3 km)
south to the dam-and campsites. The northern por-
tion of the route traverses high, rolling, tundra-
covered hills. The road will cross numerous small
streams such as Lily Creek, Seattle Creek, and
Brushkana Creek (Table E.3.20). The northern
streams, which are part of the Nenana River drainage,
contain grayling and probably other resident species.
The southern part of the road will cross and parallel
Deadman Creek, which also contains grayling and other
resident species.
The gravel road wi 11 have a crown width of 24 feet
{7.3 m). Before road construction is begun, a corri-
dor at least 10 feet {3 m) wide on either side of the
road itself will be cleared.
Short access roads wi 11 be needed to reach material
sites and disposal sites. The locations and align-
ments of these auxiliary access roads will be deter-
mined when material sites and disposal sites are
identified during final road design.
E-3-134
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2.3 -Anticipated Impacts to Aquatic Habitat
Access construction will also involve upgrading the
Denali Highway from Cantwell to the intersection with
the Watana access road, a distance of 21.3 miles
(35.5 km). Upgrading will include straightening road
curves, improving one bridge, and topping the road
with more gravel.
Within the project area, the Denali Highway crosses
several small drainages, side channels of the Nenana
River, Edmonds Creek, and Jack River. Jack River
contains grayling and the Nenana River in this region
supports several species of resident fish (Table
E.3.19).
Any bridge work or straightening associated with road
upgrading will have potential impacts similar to
those resulting from new construction. Extension
of culverts in places where the road is widened could
affect fish passage.
-Alteration of Waterbodies
Stream crossings can be a cause of adverse impacts.
Bridges and culverts used to cross streams
containing primarily grayling on the main
1
access
road need to be properly sized and bedded to ,ensure
fish passage. This subject is discussed furt~her in
Section 2.4.3. Other causes of adverse road
construction impacts can result from the
following:
• Clearing
Areas of dense or tall vegetation will have to be
cleared before road building begins. In some
upland areas with tundra vegetation, clearing
will be minimal. Clearing causes degradation of
habitat when:
Cleared areas by streams and lakes are not
stabilized and erode into the water body;
Cleared material is pushed into water bodies
causing blockage of fish movements, deposition
of organics on substrates, and localized
erosion; and
Clearing along streams affects cover, avail-
ability of food organisms, and temperatures in
the stream.
E-3-135
2.3 -Anticipated Impacts to Aquatic Habitat
In-Stream Activity
During road construction, it is often necessary
for heavy equipment to enter water bodies. This
can alter the substrate and can cause 1 ocal
turbidity and sedimentation problems •
• Erosion
Erosion can result from in-stream use of heavy
equipment, placement of fill with high organic
and/or fines content, 1 ack of stabi 1 i zat ion or
revegetation on fills and cuts, and inadequately
placed or sized culverts. The increased sedimen-
tation that may result can degrade downstream
habitats •
• Fill Placement
Fills that are placed within floodplains and
streams can remove habitat previously used by
fish. The severity of the impact depends upon
the type and amount of habitat covered.
Roads can block sheet flow to or across wetlands.
When a road with insufficient drainage bisects a
wetland, one side becomes ponded while the other
side dries. The change in water quantity affects
the vegetation and the nature of the wetland.
Some wetlands that are contiguous with streams
provide rearing habitat for juveni 1 e fish. If
the wetlands are dewatered, that habitat can be·
reduced or lost. Potential alterations of sheet
flow are being considered during the detailed
road design.
-Changes in Water Quality
As with dam construction, impacts on water quality
during road construction will result mainly from
erosion and petroleum product spills. Erosion may
occur as the result of excavation for placement of
drainage structures in streams, runoff from borrow
sites, or unstabilized fills, placement of material
within water bodies, and heavy equipment operating
within streams. The road wi 11 primarily affect
small, clear-water systems.
E-3-136
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2.3 -Anticipated Impacts to Aquatic Habitat
( i i)
Si nee the systems to be crossed by the road are
c 1 ear-water grayling streams, they will be among
the habitats more sensitive to increase in turbi-
d.ity and petroleum products. Chronic or 1 arge
spills into these streams during construction could
have severe effects upon the biota, either causing
mortalities or causing fish and their food orga-
nisms to avoid contaminated areas (Maynard and
Weber 1981; Weber et al. 1981). When equipment is
operated in streams or refueling of equipment takes
place within a floodplain, petroleum products are
likely to enter the water.
-Disruptions of Fish PofXJlations
Fish will tend to avoid areas where in-stream work
is being conducted, areas contaminated by petroleum
products or, depending on the circumstance, areas
experiencing excessive turbidity. Barriers to fish
movements and migrations are created when streams
are diverted, flumed; or blocked during installa-
tion of drainage structures. Fish can a 1 so be pre-
vented from moving upstream if drainage structures
are incorrectly installed. Pumping of water from
streams can adversely affect 1 ocal pofXJl at ions by
entraining juvenile fish.
During road construction, the area between the
Denali Highway and the Watana damsite will be
occupied by hundreds of workers. Although this
area has been recreationally utilized in past
years, it has never experienced such a large influx
of people. Unless controlled, this influx will
increase fishing pressure on the streams and lakes
in the area.
Construction of Devil Canyon Access
Road and Auxiliary Roads
Access to the Devi 1 Canyon damsite will be by road
north of the Su sitna River from Watana and by rail
from Gold Creek along the south side of the Susitna
River. The road wi 11 depart from the Watana road
north of the Watana townsite at 38.5, and will
parall e 1 Tsusena Creek for approximately 1. 5 miles
(2.5 km). The route then roughly follows the
2900-foot (878-m) contour west to Devil Creek. The
road turns south along Devil Creek for about 2 miles
(3 km) and proceeds southwesterly to intersect the
E-3-137
2.3 -Anticipated Impacts to Aquatic Habitat
Susitna River at approximately RM 150, where the road
crosses the Su sitna and parallels an unnamed creek
for a short distance, ending at the construction camp
and village site. The road between Watana and Devil
Canyon will be constructued in the same manner as the
segment from the Denali Highway (see Section
2.3.3[a][i]).
The Devil Canyon access road traverses high tundra
throughout most of its length. Dense shrub vegeta-
tion and trees are encountered when the road nears
the SU sitna River crossing downstream from Devil
Canyon. The road crosses numerous small streams
between Tsusena and Devil Creeks. Tsusena Creek
contains grayling and possibly cottids and whitefish.
Devil Creek may support populations of grayling,
suckers, cottids and whitefish. Between Devil Creek
and the Susitna River, there appear to be few areas
that provide habitat for fish. The road between
Watana and Devi 1 Canyon wi 11 be constructed in the
same manner as the Denali to Wat~na segment.
The railroad access will depart from existing rail-
road at Gold Creek and proceed north and east to the
construction campsite. It will remain on the south
side of the Susitna River. The railroad will cross
Gold Creek, which is known to contain chinook salmon
(ADF&G 1982a), and wi 11 cross several tributaries
that enter the Susitna River between Gold Creek and
Jack Long Creek (Table E.3.21). It is probable that
these tributaries do not contain fish, but they may
be an important source of clear water for Slough 19,
which is a spawning area for salmon (Figure E.3.16).
The railroad will then parallel Jack Long Creek for
approximately 3 miles {5 km). Jack Long Creek has
been documented to contain pink, coho, chinook, and
chum salmon. The railroad terminus and turnaround at
Devil Canyon will be adjacent to the upper reaches of
Jack Long Creek.
Alterations of Waterbodies
Impacts to aquatic habitat will result from stream
crossings and other instream activities. Flood-
plain and side-channel habitat in Devil Creek,
Tsusena Creek, and Jack Long Creek could be affec-
ted by road and railroad alignment. Stream cross-
; ngs and drainage structures are discussed in Sec-
tion 2.4.1(c). Impacts identified for the Denali
Highway to Watana segment are also applicable to
the Devil Canyon access.
E-3-138
r.-··,
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2.3 -Anticipated Impacts to Aquatic Habitat
Railroad construction between Devil Canyon and Gold
Creek would have impacts simi 1 ar to road construc-
tion: aquatic habitat will be affected by fills,
clearing, and stream crossings.
-Changes in Water Quality
It is expected that water quality will be affected
by turbidity and petroleum product spills as was
discussed for Watana access.
-Disruptions of Fish Populations
Fish populations in areas affected by the Devil
Canyon road, auxiliary roads, or the railroad will
experience disruptions similar to those. previously
described for Watana access.
{b) Use and Maintenance of Roads
(i) Use and Maintenence of Watana
Access Road and Auxiliary Roads
-Alteration of Waterbodies
Impacts on waterbodies during road operation will
occur as a result of continued maintenance
activities. Maintenance involves road grading and
replacement of material. Improper maintenance
techniques can result in gravel being pushed off
the roadway into streams and wetlands and in
increased erosion. Road maintenance will have a
greater impact on the smaller streams, such as
Deadman Creek, than on the Susitna River.
This section considers only the road section from
the Denali Highway to Watana dam; therefore,
impacts resulting from road construction will be
confined to streams along this road alignment.
-Changes in Water Quality
During continued road use, changes in water quality
can occur as a result of fuel spills and erosion
from poorly stabilized road surfaces and fill
areas. Large fuel spills would have the greatest
impact on the aquatic habitat.
E-3-139
2.3 -Anticipated Impacts to Aquatic Habitat
The Watana access road will cross numerous streams,
many of which contain grayling. In areas where the
road crosses or encroaches on a waterbody, an
accident involving transport vehicles, including
those carrying petroleum products, could occur.
The impacts associated with spills will depend upon
the season, the type and amount of substance
spilled, the size of the waterbody into which the
spill occurs, and the fish species present.
Erosion from unstable road cuts could be locally
chronic; however, these activities are not expected
to cause major impacts.
-Disturbance to Fish Populations
Fish have been known to avoid areas contaminated
with petroleum products (Maynard & Weber 1981;
Weber et al. 1981) and areas of excessive sedimen-
tation or turbidity. Chronic seepage of oil into
streams or lakes could render some areas unusable.
Fish impasses caused by either physical or velocity
barriers have been discussed under Section
2.3.3(a)(i).
The greatest source of adverse impacts upon fish
populations will be the increased access·ib·ility of
fish streams and lakes to fishing pressure via the
network of access roads. Without appropriate
management strategy, this will be a greater impact
than that resulting from operation of the camp.
As stated in Section 2.3.3(a)(i), the Watana access
road will cross Brushkana, Lily, Seattle, and Dead-
man Creeks as well as other small, unnamed streams.
These creeks are clear-water streams and many are
inhabited by grayling. Deadman Creek, in parti cu-
lar, is known for its large and abundant population
of grayling. The reach of Deadman Creek between
the falls and Deadman Lake is considered prime
grayling habitat. By subjecting this stream to
increased fishing pressure, many of the larger,
older fish will be removed from the population,
altering the age structure and possibly reducing
reproductive potential. A similar impact may occur
to other grayling streams in the area.
E-3-140
r::---,
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2.3 -Anticipated Impacts to Aquatic Habitat
(ii) Use and Maintenance of Devil Canyon
Access Road, Site Roads and Railroad
Aquatic habitat and fish po!)..llations will be influ-
enced by the existence of roads and railroads through
activities such as road traffic and road
maintenance.
-Alteration of Waterbodies
The majority of adverse impacts will have occurred
during road construction. Activities such as road
grading and replacement of drainage structures will
continue to affect stream systems.
-Changes in Water Quality
The ·impacts on water quality that may occur during
operation of the Watana access road, are also
applicable to the Devil Canyon access road and site
roads.
-Disruptions of Fish Populations
Disruptions of fish populations resulting from
operation of the Devil Canyon access road~ auxil-
iary. roads, and railroad most likely will be:
avoidance of areas of unacceptable turbidity, sedi-
mentation~ and contamination; blockages of fish
passage, and increased accessibility to lakes and
streams for fisherman.
2.3.4 -Transmission Lines Impacts
(a) Construction of Transmission Line
( i ) Watana Dam
The transmission 1 ine will be built from Watana dam
to Gold Creek along the Devil Canyon access road and
railroad spur. At Gold Creek the transmission system
will converge with the Anchorage-Fairbanks intertie~
which extends from Willow to Healy. The route south
of Wi 11 ow wi 11 extend to Point MacKenzie where a
submarine cable will cross Knik Arm. The terminus of
the southern leg will be the University substation in
Anchorage. The northern leg will extend from Healy
to Ester near Fairbanks.
E-3-141
2.3-Anticipated Impacts to Aquatic Habitat
The transmission line will consist of a series of
steel towers spaced approximately 1300 feet (393 m)
apart that support conductors. In this case, the
towers wi 11 be x-framed guyed towers that can carry
three conductors. From Watana to Gold Creek, there
will be two parallel sets of towers. At Gold Creek,
two lines will go to Anchorage and one to Fairbanks.
This will necessitate construction of one new line
parallel to the existing intertie between Willow and
Healy and one new 1 ine north of Healy and two new
1 ines south of Willow. With the addition of the
Devil Canyon dam, two more lines will be built from
Devil Canyon to Go 1 d Creek. This wi 11 resu 1 t in an
arrangement of four parallel sets of towers along
this segment of the lines.
From Watana to Devil Canyon, a 300-foot (90-m) wide
right-of-way will be designated. The Devil Canyon/
Gold Creek segment will require a 510-foot (153-m)
wide right-of-way. Within the right-of-way, trees
and shrubs within 55 feet {16.5 m) of the tower cen-
terline will be cleared as well as any other trees or
shrubs that may hamper construction or pose a threat
to the completed line. The width of a 3-line corri-
dor will be approximately 400 feet (120m) (Common-
wealth et al. 1982).
-Alteration of Waterbodies
Adverse impacts to waterbodies will result
primarily from clearing stream crossings, road
building, and other instream activities associated
with installation of the towers and conductors.
Permanent roads may be built to provide all-season
access. The effects of clearing a right-of-way,
and heavy equipnent traffic on an aquatic
environment have been previously discussed.
The transmission line can be divided into four seg-
ments: central (Watana to Gold Creek), intertie
(Willow to Healy), northern (Healy to Ester)~ and
southern (Wi 11 ow to Anchorage). In the central
section, the line will closely parallel the Watana-
Devil Canyon access road and railroad S(Xlr for ~ruch
of its length. It will cross Tsusena Creek, Jack
Long Creek and several small tributaries of the
Susitna River. The impact of constructing a trans-
mission 1i ne through this area wi 11 be similar to,
but 1 ess than, that of the access road. See Sec-
tion 2.3.3 for a description of river and streams
to be crossed in the central segment.
E-3-142
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2.3 -Anticipated Impacts to Aquatic Habitat
The Anchorage-Fairbanks Intertie is being built as
a separate project and will be completed in 1984
(Commonwealth et al. 1982). The Susitna project
will add another 1 i ne of towers within the same
right-of-way. The impacts will be similar to those
experienced during intertie construction. The
Environmental Assessment Report for the i ntert i e
(Commonwealth et al. 1982) discusses the expected
environmental effects of transmission line
construction in this segment. Fish streams that
will be crossed include the Nenana River, Talkeetna
River, Chuni la Creek, Susitna River, and the
Kashwitna River.
In the southern segment, the transmission line will
begin at the Willow substation approximately 0.5
mile (0.8 km) north of Willow Creek. Proceeding
first west then south, the 1 ine will be routed
between the Susitna River and the Nancy Lake area,
passing within 0.75 mile (1.3 km) of the Susitna
River. It will cross several Susitna River tribu-
taries, including Fish Creek at Approximate
Milepost (AMP) 18, before crossing the Little
Susitna at AMP 26. Few streams are crossed between
the Little Susitna River and Knik Arm at AMP 44.
Knik Arm, which is approximately 2.5 miles (4.1 km)
wide at that point, will be crossed by a submarine
cable. The Knik Arm switching station is located
between Sixmile Creek and Eagle River. From there
the transmission line bypasses Otter Lake, and
crosses the Alaska Railroad and Fossil Creek.
After crossing the Davis Highway it parallels the
Glenn Highway for about 2 miles (3 km). Ship Creek
is crossed at AMP 75 and the 1 i ne traverses the
Chugach Foot hi 11 s before terminating at the
University substation near the corner of Tudor and
Muldoon Roads. Table E.3.22 presents a list of
major streams to be crossed and the species that
inhabit them.
The streams and fish . species for the northern 1 eg
are listed in Table E.3.23--. The northern portion
begins at the· Healy substation and immediately
crosses the Nenana River, proceeding west to Dry
Creek at AMP 4. 75. The 1 i ne turns north at this
point and roughly parallels the Parks Highway for
the greatest part of its length. The Nenana River
is crossed again at AMP 2.75 and AMP 58.75. The
line ends at the Ester Substation (AMP 94.25).
E-3-143
2.3 -Anticipated Impacts to Aquatic Habitat
During the transmission line construction, it will
be necessary for heavy equipment such as hydroaxes
and drill rigs to cross streams. Several factors
will influence the severity of impact on the
aquatic habitat.
-Season in which construction takes place;
-Size of the stream;
-Type of habitat in the crossing area;
-Species present;
-Frequency of crossing;
-Type of crossing, i.e. temporary bridge, tempo-
rary culvert, low water crossing;
- Streambank configuration; and
-Streambed composition.
It is expected that small, confined streams will be
more susceptible to adverse impacts from transmis-
sion line construction than will larger streams.
If "all-weather" access is maintained for the
transmission line, a gravel road will be built
along its entire length and permanent stream cross-
ings installed, with attendant, long-lasting im-
pacts. The road and stream crossings will have to
be monitored to ensure that fish passage is main-
tained and aquatic habitat is not degraded. Al-
though the transmission corridor would be many
times longer than the access road previously de-
scribed, the range of possible impacts is similar.
The access points for construction of the transmis-
sion line will be decided during the detailed de-
sign. The Will ow to Healy section will probably
use access established during construction of the
Intert i e. It is 1 ike ly that access wi 11 require
crossing streams and wetlands and thus will expand
the area in which adverse impacts may occur because
of transmission line construction.
Details of the installation of the cable under
Knik Arm are to be developed during final design.
Knik Arm is primarily a migration route for anadro-
mous species that utilize the Knik and Matanuska
River drainages including all five species of
Pacific salmon, Dolly Varden, eulachon, and Bering
cisco. Benthic organisms and other resident spe-
cies are sparce because of the excessive amounts of
E-3-144
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2.3 -Anticipated Impacts to Aquatic Habitat
( i i )
glacial material on the sea floor. It is unlikely
that alteration of this area will have any effect
upon resident or anadromous species.
-Changes in Water Quality
It is expected that temporary increases in turbid-
ity and sedimentation will occur in streams sub-
jected to instream activities during construction
of the transmission line. Small, clear water sy-
stem populations will most likely be affected to a
greater extent than will large systems. The
effects are not expected to be long-term.
In addition, streams that are crossed will be ex-
posed to possible contamination by petroleum pro-
ducts due primarily by vehicle accidents.
-Di~turbant~ of Fish Populations
Avoidance reactions associated with increased tur-
bidity may occur. Fish will also avoid areas where
instream activities occur and, depending upon the
timing, migrations may be affected. Where the
transmission lines cross a stream, clearing may re-
move overhanging vegetation that provides cover for
fish.
Construction of the line will open areas to in-
creased fishing. During construction, this will
most likely be confined to workers. The effects
will be greater in the northern and central seg-
ments where access has previously been limited.
Devi 1 Canyon
With the addition of Devil Canyon dam, two additional
lines will be built from Devil Canyon to Gold Creek.
Significant new impacts are not expected with this
incremental addition.
(b) Ope~ation of the Transmission Line
( i) Watana Dam
Once the transmission line has been built, there will
be few activities associated with routine maintenance
of towers and lines that could adversely affect
aquatic habitat. However, maintenance of all-weather
roads would entail efforts similar to that for the
.access road.
E-3-145
2.3 -Anticipated Impacts to Aquatic Habitat
-Alteration of Waterbodies
Some localized habitat disruption could occur when
maintenance vehicles need to cross wetlands and
streams to repair damaged 1 ines or towers. Where
roads are not built in conjunction with trans-
mission lines, revegetation is allowed to proceed
to a certain extent around the towers. The vegeta-
tion is usually limited to grasses and shrubs and
small trees by selective clearing so that vehicles
are able to follow the cleared area associated with
the lines. Streams may need to be forded in order
to effect repairs. Depending on the season, cross-
ing location, type and frequency of vehicle traf-
fic, aquatic habitat in the immediate vicinity of
the crossing could be affected. In addition, down-
stream reaches may be affected by increased sedi-
mentation caused by erosion.
-Changes in Water Quality
Changes in water quality during maintenance of the
transmission 1 ines are 1 ikely to result from in-
creased turbidity, instream activities and fuel
contamination.
-Disturbance to Fish Populations
Instream activities associated with line repair and
maintenance could cause disruptions of fish popula-
tions in 1 imited areas. The greatest disruption
will result from the increased accessibility to
some fishing areas from the cleared transmission
corridor. Because the vegetation is kept rela-
tively low, hikers and all terrain vehicles can use
the corridors as trails. In winter, snow machines
will also be able to traverse these cleared areas.
This will resu 1 t in greater numbers of fishermen
being able to reach areas the pre vi au sly ex peri-
enced little or no fishing pressure. This effect
will be more acute in areas where the new trans-
mission route diverges from existing roads and
transmission lines, such as south of Willow and
north of Healy. The area between Healy and Willow
will have been subjected to disturbance and in-
creased pressure during construction of the
Anchorage/Fairbanks intertie. Any increased fish-
ing pressure along the intertie as a result of the
E-3-146
-
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2.4 -Mitigation Issues and Mitigating Measures
Susitna lines being added to the corridor will pro-
bably be minor. The presence of an operating cable
under Kni k Arm should cause no impacts to fish
populations.
(i i) Devi 1 Canyon
The addition of two additional lines is not expected
to result in significant incremental maintenance
impacts over the Watana-only scenario.
2.4 -Mitigation Issues and Mitigatihg Measures
2.4.1 -Approach to Mitigation
The objective of fisheries mitigation planning for the Su sitna
Hydroelectric Project is to provide habitat of sufficient quality
and quantity to maintain natural reproducing populations where
compatible with project objectives. This is consistent with the
the mitigation goals of the USFWS and the ADFG. In order to
accomplish this objective, the Power Authority will avoid, mini-
mize, or rectify impacts. In situations where it is not feasible
to mitigate the impact in this manner, the Power Authority will
provide compensation through propagation facilities. The first
preference will be through habitat improvement measures to in-
crease the productivity of the habitat or to provide additional
habitat within the Susitna Basin. As the last resort, fish pro-
pagation facilities would be proposed as compensation.
The priorities of the fisheries mitigation, as discussed in
Section 1.3, were determined by employing the hierarchical
approach to mitigation contained in the Susitna Hydroelectric
Project, USFWS and ADF&G mitigation policies. The five basic
mitigative actions, in order of priority, are:
-Avoiding impacts through design features or scheduling activi-
ties to avoid loss of resources.
-Minimizing impacts by carefully scheduling and locating opera-
tions, timing and coptrolling flow releases, and controlling
impacts through best management practices.
-Rectifying impacts by repairing disturbed areas to provide
optional fish habitat and reestablishing fish in repaired
areas.
-Reducing or eliminating impacts over time through monitoring,
maintenance, and proper training of project personnel.
E-3-147
2.4 -Mitigation Issues and Mitigating Measures
-Compensating for impacts by conducting habitat construction
activities that rehabilitate altered habitat or by managing
resources on project or nearby public lands to increase habitat
values.
Each of the fallowing impact issues is addressed in terms of
these five mitigation actions. Table E.3.38 summarizes mitiga-
tion features for major impact issues associated with operation
of the project. The proposed mitigation program and associated
costs are in Table E.3.39. The schedule for implementing this
program is in Table E.3.40.
2.4.2 -Selection of Project Evaluation Species
Selection of evaluation species is a necessary step in assessing
impacts and in developing mitigation plans. Various species and
life stages have different critical life requirements and respond
differently to habitat alterations. A change in habitat condi-
tions that benefits one species or 1 ife stage may adversely
affect another, and mitigation plans for one species may conflict
with those proposed for another. Selection of evaluation species
can provide a mechanism to resolve potential conflicts and to
focus the resources available for analysis and planning.
The evaluation species were selected after initial baseline stu-
dies and impact assessments had identified the dominant species
and potential impacts on avail able habitats throughout the year.
Mitigations were then developed that will reduce impacts on
habitat parameters that are expected to control populations.
Fishery resources of the Susitna River and activities associated
with the project proposal were reviewed. Evaluation species were
selected on the basis of the following criteria:
-High human use value;
-Dominance in the ecosystem; and
-Sensitivity to project impacts.
Species with high regional visibility and commercial, sport, sub-
sistence, or aesthetic value were given priority. Within this
category, species sensitive to project effects were highly rated.
Si nee the evaluation species play a dominant role in the eco-
system, they may serve as indicator species. By maintaining cri-
tical habitats for evaluation species, many of the potential im-
pacts on less sensitive species or species with a lower
evaluation priority will be mitigated.
E-3-148
,-.:--'
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2.4 -Mitigation Issues and Mitigating Measures
Based on the aquatic studies baseline reports, impact assess-
ments, and harvest contributions, four species of Pacific salmon
{chum, chinook, coho, and pink) were identified as evaluation
species for the Susitna River downstream from Devil Canyon.
Arctic grayling was selected as the evaluation species for the
impoundment.
Si nee the greatest changes in downstream habitats are expected ·j n
the reach between Devil Canyon and Talkeetna, fish using that
portion of the river were considered to be the most sensitive to
project effects. Because of differences in their seasonal habi-
tat requirements, not all salmon species would be equally
affected by the proposed project. Of the five species, chum and
sockeye salmon appear to be the most vulnerable in this reach,
because of their dependence on slough habitats for spawning, in-
cubation and early rearing (Sections 2.2.1 and 2.2.2). Of the
two species, chum salmon are the dominant species (Section
2. 2.1). The sockeye that spawn in the sloughs upstream from
Talkeetna, however, are considered to be strays from stocks in
the Chulitna and Talkeetna drainages (ADF&G 1983). Since these
sockeye do not appear to support a viable stock, they are not
included as an evaluation species. Chinook and coho salmon, are
less likely to be impacted by the project because most of their
critical life stages, such as spawning, incubation, rearing and
overwintering, occur in habitats that are less likely to be
altered by the project (Section 2.3.1). While some pink salmon
spawn in slough habitats in the reach between De vi 1 Canyon and
Talkeetna, the majority of these fish utilize tributary habitats.
The mitigations proposed to maintain chum salmon productivity
should allow sockeye and pink salmon to be maintained as well.
The chinook and coho salmon juveniles rear in the river for one
to two years prior to out-migration with much of the rearing
apparently occurring in clear water areas, such as in sloughs and
tributary mouths. Improved conditions in the mainstem are
expected to provide replacement habitat to mitigate for the
potential loss of rearing areas in slough habitats. Juvenile
overwintering habitats are not expected to be adversely
affected.
The greatest change to resident fish will occur in the impound-
ment zone. In the impoundment zone, arctic grayling were se-
lected as the evaluation species because of their abundance in
the area, their sensitivity to impacts during all seasons and
life stages, and their desi~ability as a sport fish.
In summary, the evaluation species and life stages selected for
the Susitna Hydroelectric Project are:
E-3-149
2.4 -Mitigation Issues and Mitigating Measures
(a) Devi 1 Canyon to Cook Inlet Reach
( i ) Chum Salmon
-Spawning adults;
-Embryos and pre-emergent
-Emergent fry;
-Returning adults; and
-Out-migrant juveniles.
( i i ) Chinook Salmon
-Rearing juveniles; and
-Returning adults.
( i i i ) Coho Salmon
-Rearing juveniles; and
-Returning adults.
( i v) Pink Salmon
-Spawning adults; and
embryos and pre-emergent
-Emergent fry;
-Returning adults; and
-Out-migrant juveniles.
(b) Impoundment Zone
(i) Arctic Grayling
-Spawning ad~ts;
Incubat·i ng embryos;
-Rearing; and
-Overwintering.
fry;
fry;
2.4.3-Mitigation of Construction Impacts
Upon Fish and Aquatic Habitats
Mitigation of construction impacts is achieved primarily by in-
corporating environmental criteria into pre-construction planning
and design, and by good construction practices. Incorporation of
environmental criteria into design activities and construction
of the Susitna dams and related facilities will avoid or minimize
impacts to aquatic habitats. A design criteria manual and a con-
struction practices manual are being prepared. The design cri-
teria manual will be available in June 1983, and the construction
practices manual wi 11 be one of the first tasks assigned to the
construction manager.
E-3-150
-
2.4 -Mitigation Issues and Mitigating Measures
The aquatic studies program will continue to make major contribu-
tions to pre-construction planning and design. Studies will be
used in siting, design, and scheduling of project facilities and
activities. For example, the final alignment of the Watana
access road will take into consideration the fish streams along
its route. The route is sited to avoid encroachment on streams,
to minimize stream crossings and impacts at required crossings,
and to minimize cut banks.
Biological information will be incorporated into the design cri-
teria and construction practi~es manuals. A high degree of com-
munication and cooperation will be maintained between environ-
mental staffs and design ~nd construction personnel in order to
facilitate integration of biological criteria into designs,
specifications, and construction practices.
Scheduling of construction activities during preconstruction
planning is another means of avoiding or minimizing adverse im-
pacts to fish and aquatic habitats. Whenever possible, activi-
ties will be scheduled to avoid known sensitive periods.
Continued monitoring of the construction facilities and activi-
ties will ensure that impacts to the aquatic environment .are
avoided or minimized. Monitoring can identify areas that may
need rehabilitation or maintenance and areas where previous miti-
gation measures are proved inadequate and remedial action must be
taken. Costs associated with construction monitoring are out-
lined in Table E.3.41.
Potential impacts are identified in Section 2.3. The following
is a discussion of the impact issues and the mitigation measures
that wi 11 be applied during and after construction. Those issues
considered to have the greatest potential for adverse impact to
the aquatic environment are discussed first. Avoidance, minimi-
zation, rectification and reduction of impacts are discussed.
There are no direct mitigation costs associated with these miti-
gations.
(a) Stream Crossings and Encroachments
(i) Impact Issue
Improperly constructed stream crossings can block
fish movements and/or increase siltation in the
stream. Roads with inadequate drainage structure can
alter run-off patterns of nearby wetlands and
streams. Encroachments on stream courses can alter
hydraulic characteristics and increase siltation of
streams, thereby affecting fish habitat.
E-3-151
2.4 -Mitigation Issues and Mitigating Measures
(ii) Mitigation
The objective of constructing stream crossings is to
maintain the natural stream configuration (Lauman
1976) and flow so that passage of fish is assured.
Maintenance of fish passage is required under AS-
16.05.840. Appropriate control measures will be
undertaken as a part of routine maintenance to insure
that beaver dams do not interfere with fish passage
needs. For the project area, the evaluation species
used in developing criteria for stream crossings is
arctic grayling (see Table E.3.42 for criteria to be
applied to stream crossings). In designing and con-
structing a crossing, consideration will be given to
the following presence or absence of fish/fish habi-
tat, location of crossing, type of crossing struc-
ture, flow regime, and method of installation.
-Presence or Absence of Fish/Fish Habitats
Streams having documented fish or fish habitat at
or upstream from the road crossing will be designed
to pass fish. Only those streams without fish or
fish habitat at, or upstream from, the road cross-
ing will be designed solely on the basis of hydro-
logic and hydraulic criteria.
-Location of Crossing
Project roads will be aligned and located to
m1n1m1ze the number of stream crossings. When
crossings are unavoidable, they will be located at
a right angle across the stream in a straight
stretch (Lauman 1976), and with narrow, stable
banks that do not require cutting or excessive
stabilization. The crossings will be located so
that important habitats, such as spawnings beds and
overwintering areas, are not disrupted.
-Type of Crossing Structure
Open-bottom arch culverts will be installed
wherever possible {Figure E.3.24). Multiplate
elliptical and oversized circular culverts can also
be ~sed to maintain the natural streambed (Joyce et
al. 1980a; Lauman 1976) and will be used when open
arch culverts are not feasible. Standard-size
circular culverts will only be used in drainages
that are not considered fish habitat.
E-3-152
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2.4 -Mitigation Issues and Mitigating Measures
Log stringer and temporary bridges will be used
where infrequent, light vehicle traffic is
expected. Their use on the Susitna Project will be
1 imited to the transmission 1 ine corridor. During
winter transmission line construction, snow and ice
bridges will be used to cross streams. These will
be removed before breakup to avoid blocking stream
flows.
-Flow Regime
Culverts will be designed to allow grayling passage
at critical times using the ADF&G velocity criteria
(Table E.3.42). Multiplate elliptical and
oversized circular culvert inverts wi 11 be set
below the streambed elevation to avoid perching and
will be armored, when necessary, to m1 mm1 ze
erosion at the outlet. Natura 1 stream substrate
will be placed on the bottom of the culverts over
their entire length.
-Methods of Installation
When culverts other than open-bottom arches are
used, streams will be diverted around the work area
until the crossing is completed. On small systems,
the stream may be flumed. Diversion or fluming
will reduce the amount of siltation downstream from
the construction area. Diversion will be
accomplished using ADF&G criteria {Table E.3.43}.
In some areas, roads and transmission li.nes must
parallel a stream or river. The alignment will be
away from the floodplain to the greatest extent
possible. Where this is not possible, the road
will be aligned to preclude channelization of the
stream.
The transmission towe'rs will be aligned so struc-
tures are out of streams and fl oodpl ai ns to the
best extent practicable. Instream activities will
be confined to installation of drainage structures
on access routes. Where practicable, construction
wi l1 be scheduled for winter months when heavy
equipment can cross frozen creeks without elaborate
constructed crossings.
E-3-153
2.4 -Mitigation Issues and Mitigating Measures
(b) Increased Fishing Pressure
(i) Impact Issue
The sport fishing pressure on the local streams and
lake will substantially increase. The access road
and transmission line will allow fishermen to reach
areas previously unexploited.
( i i ) Mitigation
During the construction phase, access to the streams
will be limited by closing roads to unauthorized
project personnel and general public. The Alaska
Board of Fisheries will be provided such information
as they require to manage the fisheries. Some water-
sheds, such as the Deadman Creek/Deadman Lake system,
will require modification of current seasons and
catch limits if current stocks are to be maintained.
These regulations may take the form of reduced sea-
sons or catch limits, imposition of maximum size
limits, or control of fishing methods. Since public
health regulations will not allow sport-caught fish
to be stored or prepared at public food service faci-
lities, the project policy will be that all fishing
be restricted to catch-and-release unless stated
otherwise by the Board of Fisheries.
(c) Erosion Control
(i) Imp~ct Issue
Sustained high levels of sediment in a system can
change the species composition and productivity of
the system (Bell 1973, Alyeska Pipeline Service
Company 1974). s·iltation can affect development of
fish eggs and benthic food organisms.
(ii) Mitigation
The primary mitigation measures that will be used to
minimize construction erosion are: (1) locating fa-
cilities away from the clear water fish streams; (2)
employing erosion control measures such as run off
control, stilling basins and revegetation; (3) sche-
duling erosion-producing activities at biologically
noncritical seasons (APSC 1974); (4) minimizing the
time necessary to complete the activity so that ero-
sion is a short-term, non-reoccurring problem; and
(5) maintaining vegetated buffer zones.
E-3-154
-
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2.4 -Mitigation Issues and Mitigating Measures
The natural vegetation is a major factor in
preventing erosion (APSC 1974). Clearing for roads,
transmission lines, and other facilities will be
confined to the minimum area and level necessary.
For transmission lines, only taller trees and shrubs
will be removed; the lower vegetation will not be
disturbed. Adjacent to streams, especially small
systems, cl ea ring wi 11 be done by hand. Cleared
material will be removed from the floodplain to
approved disposal sites, salvaged or burned onsite.
Disposal sites that contain cleared slash and sub-
standard materials (overburden) wi 11 be 1 ocated in
upland areas away from water bodies. Disposal sites
will be constructed so that neither run off during
breakup nor rainfall will wash silty material into
streams. This may entail run off control structures,
surrounding the disposal site with berms, or
channeling run off through containment ponds.
To preclude run off from carrying silt to water
bodies near construction sites, drainage control will
direct silty water into settling basins. Clarified
water wi 11 be discharged into receiving waters in
accordance with the Alaska Department of Environmen-
tal Conservation (ADEC) permit requirements
(AS-46.03.100).
Prompt grading, mulching, and revegetation of cut-
and-fill areas will be used to minimize erosion.
(d) Material Removal
(i) Impact Issue
Removal of floodplain gravel can cause erosion, sil-
tation, increased turbidity, increased ice buildup
caused by ground water overflow, fish entrapment, and
alteration of fish habitat.
(i i) Mitigation
Adverse impacts on aquatic habitats will be avoided
or minimized by application of the following guide-
lines which are more fully discussed in Joyce et al •
.. (1980a); and in Burger and Swenson (1977).
E-3-155
2.4 -Mitigation Issues and Mitigating Measures
Before floodplain material sites are used, it will be
determined that upland sources are inadequate to
supply the needed material. Floodplain sites will be
thoroughly explored to verify that they can supply
the necessary quantities. Important habitats such as
overwintering and spawning areas will be identified
and avoided.
Buffers wi 11 be retained between the sites and any
active channels except when draglining in the active
channel. Material will be stockpiled outside the
floodplain to avoid backing flow at higher stages and
the possibility of material being eroded into down-
stream reaches. Overburden will be disposed of in
upland sites or returned to the area from which it
was removed and contoured and planted.
Material washing operations will use recycled water
and will not discharge into adjacent streams.
The Tsusena Creek material site (Borrow Site E) will
be rehabilitated after mining has ceased. The goal
of rehabilitation will be to create productive aqua-
tic habitat. The site will be shaped and contoured
to enhance fish habitat, and all man-made items re-
moved from the site (Figure E.3.25). Exposed slopes
will be graded and seeded.
Rehabilitated areas will be monitored to ensure that
grading, revegetation and other mitigative measures
are effective. The Cheechako Creek and Susitna River
borrow sites will be inundated and will not require
rehabilitation beyond that needed to minimize ero-
sion.
(e) Oil and Hazardous Material Spills
(i) Impact Issue
Spi 11 s of oil and other hazardous substances into
streams are toxic to fish and their food organisms.
(ii) Mitigation
A Spill Prevention Containment and Countermeasure
Plan (SPCC) will be developed as required by EPA (40
CFR 112.7).
E-3-156
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2.4 -Mitigation Issues and Mitigating Measures
Equ i Jlllent refu e 1 i ng or repair will not be all owed in
or near floodplains without adequate provisions to
prevent the escape of petroleum products. Waste oil
will be removed from the site and be disposed of
using ADEC/USEPA-approved procedures. Fuel storage
tanks will be located away from waterbodies and
within 1 ined and bermed areas capable of containing
110 percent of the ta.nk· volume. Fuel tanks will be
metered and all outflow of fuel accounted for. All
fuel 1 i nes will be 1 ocated in aboveground or ground
surface utilidors to facilitate location of ruptured
or sheared fuel lines.
Vehicle accidents, although difficult to fully pro-
tect against, can be minimized by constructing the
roads with properly designed curves to accommodate
winter driving conditions. The roads will be ade-
quately signed, and during the winter, difficult
stretches will be regu 1 arly cleared and sanded. In
summer, dust cbntrol will be accomplished with
water.
State 1 aw requires that all s pi 11 s, no matter how
small, be reported to DEC ( 18AAC70.080). Personnel
will be assigned to monitor storage and transfer of
oil and fuel and to identify and clean up spilled oil
and other hazardous material.
All personnel employed on the project, especially
field personnel, will be trained to respond to fuel
spills in acordance with an approved oi 1 sp1ll con-
tingency plan. The plan will include a manual and
training program describing:
-Actions to take as a first line of defense in the
event of a fuel spill.
-Persons to contact in the construction organization
and in state agencies.
-Locations of sensitive habitats.
-Location of all oil spill control and cleanup
equiJlllent, the types of equiJlllent at each location
and appropriate procedures.
-Records to keep during an oil spill and cleanup
operation •
E-3-157
2.4 -Mitigation Issues and Mitigating Measures
Oi 1 spi 11 equ i Jlllent wi 11 be prepositi oned and ade-
quate to handle the 1 argest spi 11 expected. Person-
nel will be trained in the operation of the equip-
ment, and the equipment will be inventoried and
tested regJlarly to make sure it is in proper working
order in the event of an emergency (Bohme and
Brushett 1979; Lindstedt-Siva 1979).
(f) Water Removal
(i) Impact Issue
Fish fry and juveniles can be impinged on intake
screens or entrained into hoses and pumps when water
is withdrawn from water bodies for miscellaneous uses
during construction.
( i i) Mitigation
If possible, surface water withdrawal will be from
streams or lakes that do not contain fish. If water
must be withdrawn from a fish-bearing water body, the
Alaska Department of Fish and Game intake design
criteria will be used for all intakes.
The ADF&G criteria are that: (1) all intakes should
be screened; (2) openings in the screen should not
exceed 0.04 sq in; and (3} water velocity at the
screen should not exceed 0.1 ft/sec (0.03 m/sec). No
more than 20 percent of the instantaneous flow wi 11
be removed at any time.
(g) Blasting
(i) Impact Issue
Blasting in or near fish streams can rupture swim
bladders and damage incubating embryos.
(ii) Mitigation
The ADF&G has standard blasting guidelines that
establish the distance from waterbodies at which
charges can be detonated without harming fish.
Blasting will be accomplished using these guidelines
(Table E.3.44).
E-3-l 58
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2.4 -Mitigation Issues and Mitigating Measures
(h) Susitna River Diversions
(i) Impact Issue
( i i )
Fish passing downstream through the diversion tunnels
are expected to be 1 ost because of the high tunnel
velocities. During summer, relatively few fish are
present in the vicinity of the tunnel entrance.
During winter, resident fish are expected to
be entrained into the intake and passed downstream.
Mitigation
The segment of the fish population lost in the diver-
sion tunnel waul d be 1 ost subsequent to reservoir
filling, because of lost tributary habitat and the
expected low habitat value in the reservoir (see
Section 2.3.l[b]). Mitigation for these losses will
be achieved by the early initiation of grayling pro-
pagation, as discussed under Mitigation for Inunda-
tion Impacts in Section 2.4.4(c).
(i) Water Quality Changes
( i )
( i i)
Impact Issue
Discharge of camp effluents result in increased
levels of metals and nutrient loading. Concrete
batching plants release high alkaline effluents.
Mitigation
Effluents
standards
72.010).
will comply with ADEC/USEPA effluent
(AS 46.03.100; 18 AAC 70.020; 18 AAC
The concrete batchi ng effluent wi 11 be neutralized
and treated prior to discharge to avoid impacts
related to F>H and toxic substances (see Chapter 2,
Sections 3.2.1(b)[vi] and 3.3.1(b)[vi]).
(j) Clearing the Impoundment Area
(i) Statement of Issue
Ad verse impacts associ a ted with removing vegetation
along streams are: (1) accelerated erosion into the
streams; (2) altered temperature regimes; and (3)
operation of equipment in perennial or ephemeral
stream ways.
E-3-159
2.4 -Mitigation Issues and Mitigating Measures
(ii) Mitigation
Clearing will be scheduled as close to reservoir
fil.ling as is feasible. Disturbance to the vegeta-
tive mat will be avoided. Erosion control methods
wi 11 be employed wherever needed to mi n,imi ze unneces-
sary erosion to streams. To the extent practicable,
clearing will take place during the winter. Cleared
vegetation will be dried for one season and burned in
place. The construction practices manual will
specify reservoir clearing practices.
2.4.4-Mitigation of Filling and Operation Impacts
(a) Mitigation of Downstream Impacts
Associated with Flow Regime
( i) Impact Issue
As described in Ex hi bit A, the proposed project con-
sists of two stages: the first stage-Watana develop-
ment and the second stage-Devil Canyon development.
Each stage requires its own flow release schedule
during both filling and operation. The flow release
schedule is designed to provide a balance between
filling power generation and instream flow require-
ments of the evaluation species. The initial filling
of Watana reservoir will take approximately three
years using a flow release schedule, as shown in
Table E.3.26. After filling is complete, Watana dam
power plant will be operated as outlined in Table
E.3.32. Devil Canyon dam reservoir will be filled in
two segments. The first segment wi 11 take approxi-
mately four weeks and the second segment, occurring
one or more years later, will take five to eight
weeks. The operation of the two dam stage will
result in a flow regime as shown in Table E.3.35.
One criterion that influences the establishment of
the flow release schedule is the choice of the key
fish species and/or 1 i fe stage to be protected. In
the reach between Talkeetna and Devil Canyon, chum
salmon were given highest priority followed by
chinook, coho and pink salmon (Section 2.4.2).
As discussed in Section 2.3, a primary fishery con-
cern is the provision of flows between Devil Canyon
and Talkeetna that:
E-3-160
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2.4 -Mitigation Issues and Mitigating Measures
( i i)
A 11 ow adult sa 1 mon access to t ri bu ta ry spawning
areas;
Allow adult salmon access to slough spawning
habitat;
Maintain a suitable water depth on the spawning
beds throughout the spawning period,;
-Maintain flow through the spawning gravels during
the incubation and pre-emergence period; and
-Provide a flow-related stimulus to stimulate the
out-migration of fry.
Additional fisheries toncerns related to instream
flow needs of resident and juvenile anadromous fishes
include the need tc:
-Maintain overwintering and summer feeding habitat;
and
Maintain access to tributary spawning and rearing
habitat.
Measures to Avoid Impacts
Adverse impacts to fishery resources resulting from
flow alteration can be avoided or minimized through
selection of an appropriate flow regime. While
hydroelectric developnents with storage facilities
alter the natural flow regime in the river, changes
in streamflow patterns do not necessarily result in
adverse impacts to fish populations. For example, if
low flows are limiting fish populations, then supple-
menting 1 ow flow may resu 1 t in enhancement to that
population.
Three factors control water depth at the mouth of the
sloughs: (1) mainstem stage; (2) channel geometry;
and (3) flow in the slough. Of the three factors
contributing to access, the project will only affect
the stage at the mainstem. Thus, to avoid the impact
on access to slough habitats by adult salmon, the
project would have to provide mainstem stages suffi-
cient to freely pass fish into the sloughs. This can
only be accompli shed by pro vi ding the appropriate
mainstem stage at the sloughs during the spawning
season. Under the proposed flow regime, free access
to sloughs by adult salmon will be impaired and addi-
tional mitigation measures are needed to reduce these
impacts.
E-3-161
2.4 -Mitigation Issues and Mitigating Measures
(iii) Measures to Minimize Impacts
A flow release schedule will be used that llllnlmlzes
the loss of downstream habitat and maintains normal
timing of flow-related biological stimuli.
During project operation, minimum Gold Creek target
flows from October through Apri 1 will be rna i ntai ned
at 5000 cfs. From May to the 1 ast week of July, the
target flow will be increased to 6000 cfs to allow
for mainstem fish movement. During the 1 ast five
days of July, flows will be increased from 6000 cfs
to 12,000 cfs in increments of approximately 1000 cfs
per day. Flows will be maintained at 12,000 cfs from
August 1 through mid-September to coincide with the
sockeye and chum spawning season in the sloughs
upstream from Talkeetna.
-Winter Flow Regime (October-April)
The winter flow wi 11 be reduced during October of
the second and third year of Watana filling and
substantially increased during operation of both
project stages. The filling flow regime from
November 1 through April 30 is proposed to reflect
the inflow to the reservoir. Since minor impacts
are expected during filling, no mitigations are
proposed.
The increase in winter flows during operation of
Watana dam, however, are expected to cause substan-
tial increases in stage as the ice cover forms.
Stage increases of 3 to 4 feet (0. 9 to 1. 2 m) are
predicted. These increases in stage are expected
to overtop the berms at the upstream end of sloughs
and cause rna i nstem water to flow through some
sloughs. As discussed in Section 2.3.1(b)[iii],
this would 1 ead to reduced temperatures in the
incubation gravels, increased ice formation and
reduced s1 ough water temperatures in the spring.
The impacts associated with slough overtopping
during the winter will be minimized by increasing
the height of the berms at the upstream end of the
most productive s1 oughs downstream from the ice
front (Figure E. 3. 26). The ice front is expected
to form between Sherman (RM 130) and Portage (RM
149), depending on climate conditions prior to ice
formation (see Chapter 2, Sect. 3.2. ). Productive
sloughs that will be overtopped more frequently
than once every five years will be protected.
E-3-162
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2.4 -Mitigation Issues and Mitigating Measures
It is anticipated that sloughs 8, 8A, 8B, 8C,
Moose, A1, B, 9, 9A and 11 will need protective
berms. An estimate of costs associated with these
protective berms is given in Table E.3.39.
-Spring Flow Regime (May-June)
Breakup flood flows are reduced in the regulated
flow regimes. The primary species/1 ife stage that
would be . impacted dur·i ng spring flows are salmon
fry. It is hypothesized that the spring breakup
flows may induce salmon fry, particularly chum and
pink salmon, to move out of the sloughs and other
incubation gravels, and begin the process of out-
migration. The effects of spring breakup on fry
migration during the 1983 spring breakup period
will identify the timing of out-migration in rela-
tion to flow. This information will form the
basis for modifying the spring release schedule to
provide a sufficient flow-related stimulus. The
effectiveness of these releases will be evaluated
during the filling and operational monitoring
studies.
-Summe'r Flow Regime (July-September)
The five species of Pacific salmon enter the spawn-
ing areas during the summer high flow periods.
Most of the spawning in the Devil Canyon to
Talkeetna reach is confined to sloughs and tribu-
taries. Access to the slough spawning areas is
apparently provided by a combination of the high
summer flows in the Susitna River mainstem and the
summer surface inflow to the sloughs. In addition,
the useable spawning area in sloughs is at least
partly controlled by backwater levels from the
mainstem into sloughs. Upwelling ground water in
the sloughs attracts adults, maintains the perme-
ability of spawning gravels, and provides a stable
winter flow durjng the embryo incubation period.
The primary species/life stage that would be
impacted in the summer is adult chum salmon.
The proposed operational flows from August 1 to
September 15 will provide 12,000 cfs at Gold Creek
and will reduce, but not avoid impacts to spawning
salmon. It is anticipated that adult salmon will
still experience difficulty in gaining access to
the sloughs. A refinement of these mitigation
flows is being analyzed.
E-3-163
2.4 -Mitigation Issues and Mitigating Measures
The mitigation increment proposed release for
August 1 to September 15 is approximately 387,000
acre-feet. This water has been allocated to pro-
vide 12,000 cfs downstream flows during spawning
season. At present, this volume is distributed
evenly between July 25 and September 15, when adult
chum and sockeye are returning to slough spawning
areas. Alternatively, this mitigation volume can
be allocated in a series of short-term augmented
discharges of variable magnitude, frequency and
duration that minimize impacts to different species
life stages and maximize use of the available water
volume. The optimal flow regime w"ill be determined
from an analysis of the habitat requirements of the
evaluation species that is currently in progress
through the aquatic studies program. This informa-
tion will contribute to the evolution of the reser-
voir operation regimes.
Even though the use of short-duration pulsed flows
will increase ease of access into sloughs, it is
expected that impacts to spawning salmon wi 11 not
be completely avoided through flow allocation. The
flows are of sufficient magnitude, however, to
permit rectifying impacts to salmon spawning
activity.
(iv) Rectification of Impact
-Winter Flows
Since impacts are mitigated in the preceeding
section, rectifying measures are not needed.
Spring Flows
If salmon fry require a high flow at breakup in
order to stimulate out-migration, a properly timed
pulse of sufficient magnitude will be provided.
-Summer Flows
Impacts to salmon spawning areas wi 11 occur if
mitigation measures are not employed in coordina-
tion with the proposed project flows (or the alter-
native regime of short-term augmented flows). The
rectification methods selected are (1) to maintain
access to the sloughs; and (2) to ensure suitable
spawning and incubation habitat by physically
modifying the sloughs, to maximize use of reduced
E-3-164
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2.4 -Mitigation Issues and Mitigating Measures
filling and operational summer flows. The follow-
; ng habitat enhancement measures wi 11 be applied
either singly or in combination on sloughs, depend-
ing on the type of impact that limits salmon pro-
duction. These methods, especially if used in
combination with short-term augmented flows during
the spawning season, will maintain salmon produc-
tivity in the sloughs. Sloughs on which rectifying
measures will be used are sloughs 8, 8A, 88, 8C,
Moose, A1, B, 9, 98, 9A, 11, 17, and 21. These
sloughs accounted for over 97 percent of the spawn-
; ng chum and 98 percent of the spawning sockeye
using sloughs in 1981 and 1982. Estimates of costs
associated with these mitigations are provided in
Table E.3.39 •
• Acces~ Mitigation
The project flows during August may not create
sufficient backwater effects at the mouths of
some sloughs to permit free access by returning
adult salmon. Access to these sloughs wi 11 be
facilitated by restructuring the ent ranee of the
slough to convey the majority of the slough
discharge and thus provide a greater passage
depth (Figure E.3.27). The mitigation plan
provides for eight restructured slough mouths.
After the adults enter some of the sloughs, they
ascend long reaches of shallow water over a steep
gradient before entering the spawning pools. If
the ground water flow is substantially reduced,
the depth of the spawning pools is also likely to
be reduced. In order to rectify these impacts,
the streambed profile of the impacted sloughs
will be lowered to re-establish the head between
the mainstem and slough (Figure E.3.28). Lower-
ing of the slough profile will reestablish the
backwater effect at the mouth of the slough and
allow free passage through the slough and use of
the spawning areas. Lowering of the slough pro-
file will reestablish the area of ground water
upwelling that was reduced by the lower mainstem
flows. Preliminary calculations indicate a
lowering of 1.5 feet (0.5 m) will accomplish the
objectives. The mitigation plan provides for
lowering the profile of eight sloughs. Such
techniques have been successfully used in British
E-3-165
2.4 -Mitigation Issues and Mitigating Measures
Columbia to improve chum salmon spawning
et al. 1980) and are further discussed
Wood Leidal Association and D.B.
Association (1980).
(Lister
in Ken
Lister
During the lowering process, the slough will be
structured to optimize spawning habitat (Figure
E. 3. 28). If it is assumed that 50 percent of the
area in these lowered sloughs will be useable
spawning habitat, then 144,000 square feet
(12,960 m2) of spawning habitat will be made
available by this process (Table E.3.46) •
• Spawning Habitat Mitigation
If it is detennined from the ongoing aquatic
studies that the reduction of upwelling area
under operational flows will reduce available
spawning area to the extent that salmon produc-
tivity is decreased, then additional methods will
be employed to augment upwelling in the sloughs.
This will be accomplished by pi ping water down-
gradient to a series of perforated drainage pipes
to enhance the volume of upwelling in the slough
(Figure E.3.29). The mitigation plan provides
for four systems to augment upwelling. These
four upwellin~ systems will serve 48,240 square
feet (4341 m ) of spawning habitat (Table
E.3.46).
As the ongoing studies define the habitat re-
quirements of the evaluation species, hydrology
of the sloughs and as flow regimes are refined,
it will be possible to detennine mitigation mea-
sures appropriate to each of the sloughs. The
final selection and design of mitigation features
for each slough wll be derived in consultation
with NMFS, USFWS and ADF&G.
(v) Reduction of Impacts Over Time
A monitoring program will be conducted to evaluate
the effectiveness of mitigation measures (see Section
2. 6) •
(vi) Compensation for Impacts
If the flow-related impacts cannot be minimized,
rectified, or adequately reduced with the implemented
E-3-166
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2.4 -Mitigation Issues and Mitigating Measures
mitigation measures, it will be necessary to compen-
sate for the 1 ost fishery resources. The goal of
this compensation wi 11 be to produce the number of
fry expected to be lost from the impacted area. The
first priority for compensating 1 ost salmon produc-
tivity will consist of channel modifications in side-
channels and mainstem areas to increase the suita-
bility of these habitats for spawning.
The lack of suitable substrate may limit the avail-
ability of spawning habitat under project operation.
In areas with suitable hydraulic conditions, the
addition of gravels or the cleansing of gravels in
areas with suitably sized particles will provide
additional habitat needed to accommodate adults
displaced from other habitats. Such projects have
been successfully undertaken in Washington (Gerke
1974; Wilson 1976; Washington Department of Fisheries
1981) and British Columbia (Lister et al. 1980).
Estimates of costs associated with these mitigations
are provided in Table E.3.39.
-Scarifying S1de-Channels
Some of the existing side channels have substrates
suitably sized for spawning, but the particles are
cemented together by glacial silts and sands. The
heavy sediment 1 oad and peak flows that presently
exist in the Susitna River have resulted in a high
degree of compaction in the substrate. If the
sands and silts cementing the gravels together are
removed, it is expected these areas wi 11 provide
suitable spawning habitats. In some of these side
channels, a bulldozer with a scarifier will be
used, in combination with a high-flow release, to
rake the streambed, stir up the fine sediments
(Gerke 1974; Wilson 1976; Trihey 1982b; Kerr Wood
Leidal Association and D.B. Lister Association
.1980), and allow the fines to be carried away by
the streamf1ow. This enhancement will be accom-
plished during reservoir filling. During filling
and operation, there will be a reduction of the
suspended sediment load and flood peaks (Chapter 2,
Section 3.3.2 and 3.3.3), which will be beneficial
in maintaining these 'areas after cleaning. The
mitigation plan provides for scarifying four side
channels. The four scarified side channels will
provide 120,060 square feet (10,805 m2) of spawn-
ing habitat (Table E.3.46).
E-3-167
2.4 -Mitigation Issues and Mitigating Measures
-Slough Gravel Cleaning
In areas where the above technique will not work, a
mobile gravel cleaning machine will be used to re-
move silts and sands from the substrates. "Gravel
Gertie," developed by Washington State University,
may be suitable for use on slough and side-channel
substrate. "Gravel Gertie" is a mobile gravel
cleaner that uses high-velocity water jets to flush
and then collect the silts from gravels for dispo-
sal (Mih 1980). Silts and sands removed from the
gravels will be discharged into the mainstem river
or disposed of on 1 and. Habitat improvement act i _.
vities on side channels will be conducted in a
downstream sequence to reduce the chance of sedi-
mentation of fines from upstream sites impacting
downstream sites. Rehabilitation projects of this
nature have been successfully used for maintaining
chum salmon sloughs in Washington (Washington
Department of Fisheries 1981). It is anticipated
that all productive sloughs wi 11 need maintenance
cleaning on a 4-to 5-year cycle. The mitigation
plan provides for cleaning gravel in three sloughs
per year.
-Mainstem Spawning Beds
Under project operation, the peak flow events will
be significantly reduced in the reach from
Talkeetna to Devil Canyon (Chapter 2, Section
3.3.3[a]). Some side channels and areas of the
mainstem will have suitable hydraulic conditions
for spawning under project operation, but the
streambed may not have substrate of appropriate
particle size for spawning. In these areas, gravel
spawning beds wi 11 be added to create spawning
habitat (Figure E.3.30). Thus, gravels placed in
side channels and the mainstem to create suitable
spawning habitat will have a greater probability of
remaining stable under operational conditions. The
mitigation plan provides for construction of two
mai nstem spawning beds. These two beds wi 11 pro-
vide 120,015 square feet (10,800 m2) of spawning
habitat (Table E.3.46).
Cleaning and supplementing spawning gravel cannot
be implemented until reservoir filling. Material
added to the mainstem and many of the side channels
prior to the control of flow would be quickly re-
distributed during pre-project summer floods. An
E-3-168
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2.4 -Mitigation Issues and Mitigating Measures
analysis of candidate areas is being conducted to
identify suitable sites.
-Chum Salmon Hatchery
A chum salmon hatchery facility will be constructed
if the previously described, higher priority, fish
mitigation alternatives cannot be successfully
implemented. Nine potential chum sal man hatchery
sites have been identified and evaluated within the
Susitna River basin based on water quality, indi-
genous fish species, access to electricity and
roads, soil characteristics, and land ownership
status of the respective sites (Kramer, Chin and
Mayo, Inc. 1983).
A decision to implement hatchery production of sal-
mon within the Susitna basin would require defini-
tion of appropriate target species, management
goals, stock'selection, disease problems, and would
cause competition with native stocks.
(b) Mitigation of Downstream Impacts Associated
with A 1 tered Wate·r Temperature Regime
(i) Impact Issue
The creation of Watana and Devil Canyon reservoirs
will change the downstream temperature regime of the
Sus itna River. Reservoirs act as heat si nk.s, reduc-
ing the annual variability and the rate of change in
water temperatures by moderating summer and winter
temperatures and introducing a time lag. The magni-
tude of change in the thermal regime downstream de-
pends on the thermal stratification of the reservoir
and the design of the power intake and release struc-
tures.
Some seasonal stratification is expected to occur in
Watana Reservoir (Figure E.2.106). Reservoir thermal
modeling indicates that surface water temperatures
will reach 10°C (50°F) by August 1 and that the top
100 feet (30 m) of the water column will range be-
tween 8° to goc {44.4° to 48.2°F) (Chapter 2, Section
3. 3. 3( c ) [ i J ) •
The water temperatures downstream from the dam are
set in part by the elevation of the intake struc-
tures, which in turn determine the temperature of the
water drawn from the reservoir. Since growth rate in
E-3-169
2.4 -Mitigation Issues and Mitigating Measures
many aquatic organisms is temperature-dependent,
changes in the thermal regime can have profound
impacts on aquatic communities. Potential adverse
effects of higher winter temperatures include accele-
ration of incubation and early emergence of salmonid
embryos and benthic invertebrates. The impact of
lower summer temperatures includes slower growth of
invertebrates, juvenile anadromous, and resident
fish. The lag effect may cause delayed spring spawn-
ing activity. Changes in the thermal character and
its effects will decrease downstream as tributaries
contribute to the flow and as the temperature regime
approaches an equilibrium state. The impacts related
to the thermal changes are expected to be confined to
the Talkeetna to Devil Canyon reach.
(ii) Measures to Avoid Impacts
The only mitigative alternative that would completely
avoid temperature changes downstream from the project
is no project alternative. Hydroelectric project
involving reservoir storage dams will alter the
natural temperature regime.
(i i"i) Measures to Minimize Impacts
The impacts associated with alteration of the temper-
ature regime during reservoir operation will be mini-
mized by incorporating multi pl e-1 evel gates in the
power intake. Multiple level intakes have success-
fully regulated temperature of downstream releases
{Nelson et al. 1978).
The success of temperature regulation depends on the
thermal structure of the reservoir and the 1 ocation
of the intake ports. The reservoir operation model
was used in the design of the multilevel intake
structure. The cost of providing multi 1 evel intake
structure for temperature control is provided in
Table E.3.39.
The summer pre-project temperatures range from 8° to
12°C (44.4° to 53.6°F) in the Devil Canyon to
Talkeetna reach. Temperatures near this range are
projected to exist in the top 100 feet (30m) of the
reservoir (Chapter 2, Figure E.2.106). By accessing
this layer with the multiple-level intake, outlet
water temperatures will approximate existing baseline
water temperatures from the end of June to
mid-September.
E-3-170
....
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2.4 -Mitigation Issues and Mitigating Measures
(c)
During the winter months, temperatures in the main-
stem are near ace (32cF) in the De vi 1 Canyon to
Talkeetna reach. Water temperatures 1c to 4cc (33.8c
to 39.2cF) are likely to occur in the Watana reser-
voir to a depth of 1aa feet (3a em), below which tem-
peratures will be a uniform 4cc (39.2cF) (Chapter 2,
Section 3.2.3[c]). Surface water released at 4°C
(39.2cF) from Watana dam in early November are expec-
ted to reach ace (32cF) by RM 1a3, while later in the
winter, surface water released at 2°C (35.6cF) from
Watana dam in early January are expected to cool to
near ace (32°F) by RM 156, just above Devil Canyon.
Mitigation of Inundation Impacts on
Mainstem and Tributary Habitats
(i) Impact Issue
In 1981, the arctic grayling population in the im-
poundment area of both reservoirs, exclusive of
Watana Creek, was estimated to be approximately 9375
grayling greater than 8 inches (20 em) (Table
E.3.17), while in 1982 the total population was esti-
mated as at 1 east 16,3aa (ADF&G 1982e). This poj:lll a-
t ion uses the clear-water tributaries as spawning and
rearing habitat and the tributaries and Su sitna River
mainstem as overwintering habitat. A major project
impact will be the loss of grayling spawning and
rearing habitat in the inundated portion of the tri-
butaries.
(ii) Measures to Avoid Impacts
The only mitigation alternative that will avoid im-
poundment impacts for the proposed project is the no
project alternative.
(tii) Measures to Minimize Impacts
Mitigation measures that would substantially minimize
impoundment impacts to fish populations would be to
substantially lower the surface elevation of the
reservoir or to maintain surface 1 evel during the
embryo incubation period. Neither measure waul d be
feasible.
(iv) Measures to Rectify Impacts
Since the impoundment is essentially a permanent
impact, rectification measures are not feasible.
E-3-171
2.4 -Mitigation Issues and Mitigating Measures
Rectifying measures, such as providing replacement
grayling spawning habitat within the impoundment are
not considered feasible because of the timing and
magnitude of the drawdown cycle.
(v) Reduction of Impacts
Impacts cannot be reduced over time since no effec-
tive mitigation measures have been identified.
(vi) Compensation for Impacts
A propagation program will be initiated to compensate
for the loss of these grayling. In order to compen-
sate for the loss of grayling, in-kind, in-basin
replacement is planned. Compensation for loss of
aquatic habitats in the two reservoirs will be ac-
complished by:
-Funding research on grayling propagation tech-
nology;
-Hatchery propagation of grayling or other resident
species and subsequent planting of the reared fish;
-Introduction of rainbow trout into the Devil Canyon
reservoir.
Estimated costs of these mitigations are provided in
Table E.3.39.
-Grayling Propagation Technology
Artificial propagation of arctic grayling using
existing techniques is not expected to produce the
number of adults or adult-equivalents needed to
compensate for the expected 1 asses. At present,
grayling propagation in Alaska consists of strip-
ping eggs from wild adults, incubating the embryos
until hatching, then releasing the newly hatched
larvae. This technique is limited by the avail-
ability of gravid wild adults, substantial larval
mortality, and no satisfactory way of measuring
success. If the larvae are artificially reared for
two to three months until they are past the larval
stage, the early mortality can be substantially
reduced. Gray1 ing of this size, approximately 1.4
to 2 in. (3 .5 to 5 em), can be marked so that the
success of the program can be evaluated.
E-3-172
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2.4 -Mitigation Issues and Mitigating Measures
Prior to construction of Watana dam, the project
will fund research on the rearing of grayling
larvae so that the technology will be available
when the compensating grayling are needed. This
research will also provide the ADF&G with an addi-
tional fisheries management tool. The research
program caul d be conducted under the a us pi ces of
ADF&G at an existing hatchery facility and financed
by the project.
-Hatchery Propagation of Grayling
or Other Resident Species
After the demonstration of a successful technology
for grayling rearing, a grayling hatchery program
will be undertaken either by expansion of an exist-
ing facility or construction of a new facility. A
drawing for a grayling hatching and rearing facil-
ity is shown ·in Figure E.3.31.
Hatchery produced grayling will be planted in 1 akes
in the project area. The number of grayling to be
planted and number of lakes to receive grayling
will be determined based on the carrying capacity
of the selected lakes. Sufficient grayling will be
planted so that the number of catchable grayling
will be similar to that number lost. If suitable
habitat does not exist in the vicinity of the im-
poundment to support the number of lost grayling,
suitable areas outside the project area will be
selected for stocking grayling. The lakes to be
stocked will be selected in consultation with
ADF&G, USFWS, BLM, and adjacent land owners.
Preference will be given to areas near the project
area that currently support high levels of harvest
pressure.
If the grayling rearing program is not technically
feasible or if appropriate planting areas do not
exist, the alternative compensation is to provide
artificially reared rainbow trout. The technology
of rearing rainbow trout is well established and
there is a high demand for the species. An exist-
ing facility would be expanded and the trout made
available for stocking outside the project area in
consultation with ADF&G, USFWS and BLM. Costs will
be similar to those estimated for the grayling
propagation program.
E-3-173
2.4 -Mitigation Issues and Mitigating Measures
-Introduction of Rainbow Trout
into Devil Canyon Reservoir
The Devil Canyon reservoir, unlike the Watana res-
ervoir, is expected to contain habitats favorable
for fish production. The Devil Canyon reservoir
contains several tributaries that will support
rainbow trout spawning, primarily Tsusena Creek and
Fog Creek, but also Cheechako Creek and several
unnamed tributaries. At present, the natural range
of rainbow trout ends at Devil Canyon, where up-
stream movements are blocked.
It is expected that rainbow trout will make full
use of reservoir habitats by spawning and rearing
in clear-water tributaries and rearing and over-
wintering in the reservoir. Rainbow trout to be
p 1 anted in the reservoir wi 11 be acquired from
existing facilities within the state. A stocking
program wi 11 be estab 1 i shed in consultation with
ADF&G.
(d) Mitigation of Downstream Impacts
Associated with Nitrogen Supersaturation
(i) Impact Issue
Nitrogen supersaturation in outflow waters has caused
significant fish mortalities from gas bubble disease.
Water passing over a high spillway into a deep plunge
pool entrains air. Nitrogen passes into solution at
depth and a state of supersaturation exists when the
water returns to the surface causing persaturation.
The degree to which this occurs depends on the depth
of the plunge pool, height of the spillway, amount of
water being spi 11 ed, and downstream tu rbu 1 ence.
Supersaturated water is unstable and eventually will
return to equilibrium levels if exposed to the air.
However, travel time downstream during high flow
periods can be fairly short, causing supersaturation
to extend considerable distances downstream.
(ii) Measures to Avoid Impacts
Gas supersaturation will be avoided by including
fixed-cone valves in the outlet facilities. These
valves, in combination with the powerhouse flows,
will discharge all flood flows up to the 1:50-year
flood without causing supersaturation. A prototype
test of cone valves showed them to be effective in
E-3-174
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2.4 -Mitigation Issues and Mitigating Measures
( i i i )
preventing gas supersaturation (Ecological Analysis
Inc. 1982). Costs associated with providing the gas
supersaturation control structures are provided in
Table E.3.39.
Measures to Minimize Impacts
The likelihood of creating gas supersaturation down-
stream from the dam wi 11 be reduced by mi nimi zing
release through reservoir management. Releases occur
when the reservoir is full and inflow exceeds out-
flow. By holding the reservoir below full pool for
most of the year, flood control capacity would be
increased, thus decreasing the probability of spills.
The reservoir must reach maximum storage level by
September 30 to meet winter power demands. Storms do
occur in the Susitna drainage that may require re-
lease of water; however, the structures and operation
criteria have been designed to minimize releases and
spills.
2.4.5-Cumulative Effectiveness of Mitigations
{a) Construction Mitigation
Through siting and designing of project facilities, appro-
priate construction practices, and careful scheduling activ-
ities as discussed in Section 2.4.3, it will be possible to
minimize adverse impacts to aquatic habitats resulting from
project construction: The indirect impacts caused by
increased access to harvestable fish populations will be
reduced during construction by providing workers with alter-
nating recreational opportunities, by instituting a catch-
and-release policy for project workers, and by supporting
such harvest regulations as the Board of Fisheries imposes.
It is expected that impacts will not be avoided and that
increased access wi 11 have long-tenn impacts on fish popul a-
tions cau~ed by the increased harvest pressure.
Aquatic habitat will be .altered by removing gravel from the
floodplain. These impacts will be rectified by rehabilita-
tion practices discussed in Section 2.4.3.
Fuel spills and road runoff will decrease water quality in
streams down hi 11 from project roaQs. These impacts wi 11
be reduced by having a properly trained and equipped spill
response team at the construction site.
£-3-175
2.4 -Mitigation Issues and Mitigating Measures
The construction monitoring team will identify areas where
remedial actions such as repair, realignment, or redesign
are needed.
(b) Operatioh Mitigation
(i) Mitigations of Access and Impoundment Impacts
The primary program design is to mitigate residual
impacts of the access road and reservoir and to com-
pensate for these losses by artificially propagating
grayling and introducing these grayling into suitable
project and non-project area waters. As part of this
compensation, research on grayling propagation will
be funded to increase fishery management options.
The target number of grayling to be produced will be
equivalent to the number lost in the impoundment.
The target number of grayling to be produced will be
equivalent to the number lost in the impoundment.
The primary areas considered for planting are
project-area 1 akes that are capable of supporting
grayling. If grayling propagation proves not feas-
ible, rainbow trout will be substituted for planting
outside the project area.
Where feasible, access will be provided to the
stocked areas to divert harvest pressure from adja-
cent natural populations. Additional artificially
produced grayling can be introduced into project-area
streams if natural populations become depleted and
population enhancement is deemed to be desirable by
the ADF&G. If the carrying capacity of project-area
enhancement sites is exceeded by the number of gray-
ling available, the excess grayling will be made
available for planting outside the project area.
Final decisions on the distribution of residual gray-
ling will be made in cons~tation with ADF&G, USFWS,
BLM, and adjacent landowners.
Road access to the project area wi 11 result in in-
creased resource use. Angling pressure would be con-
trolled by the Board of Fisheries through harvest
regulation including catch limits, restrictive cap-
ture techniques (e.g., fly fishing only and single
hook}, and adjustments in the open season.
E-3-176
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2.4 -Mitigation Issues and Mitigating Measures
( i i ) Mitigation for Downstream Impacts
The goal of the downstream mitigation program is to
provide adequate habitat downstream from Devil Canyon
Dam that will m1n1m1ze adverse impacts on fish
resources. It is anticipated that the mitigation
program wi 11 fully maintain, and probably enhance,
salmon productivity in the Devil Canyon to Talkeetna
reach. During the development of the mitigation pro-
gram, volumetric, temporal, physical, and chemical
needs of the anadromous fish resources between Devil
Canyon and Talkeetna were evaluated. Studies and
modeling of the inter-relationships of these para-
meters will continue to refine and quantify the miti-
gation program.
Several project featiJres have been incorporated i nt.o
the desi.g.n to avoid or reduce impacts. Fixed-cone
valves will be installed in the outlet facilities to
prevent gas supersaturation. The multiple-level
power intake gates will allow water to be withdrawn
from the upper 1 evel s of the water column over the
full drawdown range. This ability to withdraw water
from the upper levels will allow control over down-
stream temperatures during periods of stratification.
The project operational flows were developed with an
intent to provide a maximum flow during the summer
that would not substantially affect the project
economics or energy production capabilities. These
operational flows will alter the physical charac-
teristics of the sloughs, thereby reducing ease of
access and available spawning area for adult salmon
and increasing embryo mortality if the sloughs de-
water or freeze after spawning is completed. Fry
that survive may not leave the sloughs if the migra-
tion stimulus, possibly a combination of a proper
temperature and flow pattern, is eliminated.
The project operational flows will allow downstream
impacts to be minimized when used in conjunction with
proposed rectifying and compensating measures. The
primary rectifying measure is to use stream enhance-
ment techniques to modify natural slough habitats to
maintain natural salmon spawning and fry production.
The slough enhancement process is composed of a
series of steps to rectify the loss of natural slough
habitat. These steps may be used singly or in combi-
nation in any particular area, depending on the con-
trolling factors in an affected slough. These steps
are:
E-3-177
2.4 -Mitigation Issues and Mitigating Measures
-Providing an upstream berm that will prevent the
river from entering the enhanced slough during
winter staging. This control maintains the in-
tegrity of the spawning gravels and reduces thermal
impacts.
-Selecting a slough that retains ground water flow
with suitable thermal characteristics under opera-
tional flow levels. The selection process is eval-
uating a number of criteria to assess the potential
for the slough to maintain sufficient ground water
flow under operational flows to maintain salmon
embryos through the winter and allow properly timed
development. Emphasis will be on sloughs that are
currently most productive.
-Providing adult salmon with access into the slough
by enhancing the backwater effect at the slough
mouth and lowering the slough profile.
-If ground water flow cannot be naturally maintai~ed
by lowering the slough profile, areas where the
ground water flow can be artificia1ly maintained
will be considered.
The extent and type of habitat enhancement depends on
natural site characteristics, such as ground water
flow rates, size of natural features, and factors
that appear to 1 imit salmon productivity in each
slough. The number of sloughs modified will depend
on the desired level of production. It is the Power
Authority 1 s intent to maintain production at histori-
cal locations and levels.
In addition to slough modification, mainstem spawning
beds will be provided as a compensation measure.
Additional mainstem and side channel spawning areas
will be provided by scarifying or cleaning compacted
gravels.
The proposed rectifying and compensating actions will
provide an estimated 432,315 square feet
{38,902 m2) of spawning habitat (Table E.3.46~.
This total is over 187,000 square feet (16,830 m )
greater than the maximum estimated spawning habitat
required by salmon spawning in sloughs upstream from
Talkeetna in 1981 and 1982. It is expected that
these mitigation features will allow salmon popula-
tions in the Devil Canyon to Talkeetna reach to in-
crease over historical levels.
E-3-178
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2.5 -Aquatic Studies Program
The aquatic studies program is an integral part of the continuing plan-
ning and design for the Susitna Hydroelectric Project. The information
presented in this document is primarily based on results of 1981 field
studies with some preliminary information from the 1982 study program.
Interpretation and analysis of the 1982 data are in progress and sup-
plemental reports containing the results of these analyses wi 11 be com-
pleted in June 1983. Continuing field data collections have been
funded through the 1982-1983 winter season. Modeling efforts have been
initiated to incorporate all project data into a quantified impact
assessment. Scopes of work for the 1984 field season are being de-
veloped. As additional information becomes available from field
studies and impact analysis, the mitigation plan will be refined and
detailed plans specifying number, location, and design of mitigation
features will be prepared. The Power Authority will provide details of
these studies and plans as they become available.
As a more refined understanding of project impacts and viable mitiga-
tion features is acquired, the emphasis of the study program will shift
towards providing the design criteria needed to implement the mitiga-
tion features. The aquatic studies will produce the information
required to prepare mitigation programs for the preconstruct ion, con-
struction, filling, and operational phases of the project and phases
into a long-term monitoring program.
2.5.1 -Preconstruction Phase
During the preconstructi on phase, the aquatic studies program
wi 11 :
-Provide supplemental information required for support of the
license application;
-Continue to define seasonal habitat relationships;
-Continue quantifying the predicted impacts; and
-Refine the proposed mitigating measures ..
The need for speci fie tasks will be translated into field pro-
grams.
2.5.2 -Construction Phase
During the planning for construction, information will be needed
to properly design site facilities and schedule construction
activities to avoid impacts to aquat~c habitats. Incorporating
environmental design criteria into design, siting, and scheduling
activities is a major feature of the construction mitigation
plan. Review of proposed actions and fadl ities will generate
E-3-179
2.6 -Monitoring Studies
the need for some additional data. These needs will be transla-
ted into an orderly field study program. Environmental design
criteria will be incorporated during the plannin9 stage in order
to avoid or minimize impacts.
2.5.3-Filling and Operation Phases
During filling and operation, monitoring studies, as discussed
below, will permit refinement of mitigation features to improve
performance.
2.6-Monitoring Studies
As discussed in Section 1.3 and the Susitna Hydroelectric Project Miti-
gation Policy Report, monitoring studies are recognized as an essential
project mitigation feature that provides for a reduction of impacts
over time. Monitoring will be conducted during project construction
and operation:
-To insure that good construction practices are being employed on the
project;
-To evaluate the effectiveness of the operation and maintenance of
mitigation features; and
-To recommend changes in construction practices or mitigation features
to further avoid, minimize, or reduce impacts.
An interagency mitigation monitoring team will be established to ensure
the proper and successful execution of the mitigation plan and to
determine its effectiveness. The organization and operation of a
monitoring team will be determined through discussions with resource
agencies leading to a memorandum of understanding.
2.6.1 -Construction Monitoring
Construction monitoring will consist of monitoring construction
activities to ensure that proper construction practices, as
detailed in the project construction practices manual, are being
followed and that project facilities are being properly main-
tained. This monitoring activity will cover all project facili-
ties, i ncl udi ng access road construction and rna i ntenance, camp
and village construction, material removal, washing operations
for dam construction, reservoir clearing, abandonment, and reha-
bilitation activities.
E-3-180
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2.6 -Monitoring Studies
As outlined in the project schedule, construction of the main
access road will begin in January 1985. From that time, until
construction of the project is complete, a team of construction
monitors will be present at the project site. On a daily basis,
the monitoring team will visit areas where construction is
occurring. Their primary responsibility will be to provide
guidance on permit compliance relative to daily activities.
Prior to constructing facilities, the environmental team will
review the final designs and means of construction with regard to
permits, license stipulations, and design and construction cri-
teria manuals. This will ensure conformance to approved prac-
tices. Once construction has begun, onsite changes in permit
stipulations may be required because of changes in construction
techniques or accidents. If a variance is required, a represen-
tative from the regulatory agencies who will be present onsite,
will have the authority to authorize field actions that were not
specified in the permits. After facilities or portions of facil-
ities have been constructed, the monitoring team will review the
designs and verify that the facility is in compliance with permit
and license stipulations.
Throughout the construction period, the implementation and execu-
tion of the monitoring program will be the responsibility of the
Power Authority but daily management will be delegated to the
design manager. The construction monitoring teams in the field
will report on a regular basis to the design manager. The
design manager, in turn, will be responsible for relaying appro-
priate information to the Power Authority. lf a variance is
requested by construction crews in the field, the construction
and design managers as well as the Power Authority will be noti-
fied.
The canst ruction monitoring crew will determine compliance with
permit or license stipulations. If a facility or activity is
found not to be in compliance with existing stipulations and if a
variance was not requested prior to implementing the acitivity, a
certificate of non-compliance will be issued and all responsible
parties will be notified.
The construction schedule and proximity of activities will dic-
tate the size and number of monitoring teams. Early in the con-
struction phase (1985-1988), the monitoring team will be small,
since activities will be limited to construction of the access
road and to the Watana dam site. Beginning in 1989 and extending
through 1991, the construction of the Anchorage to Fairbanks
transmission line will necessitate a larger crew operating over a
much larger area. By 1994, the transmission line and Watana dam
will be complete; however, construction of site facilities at
E-3-181
2.6 -Monitoring Studies
Devil Canyon will just be starting. During this interim period,
the number of monitoring teams and the extent of their coverage
will be reduced. The construction of the main dam at Devil
Canyon in 1996 will result in only a small increase in the size
of the monitoring team, since most activities will be limited to
the damsite and the access road. As indicated by the current
schedule, construction activities, including the monitoring
program, will end in 2002.
2.6.2 -Operational Monitoring
Operational monitoring will be conducted to (1) monitor salmon
population and production levels to ensure that the predicted
level of impact is not being exceeded, and (2) evaluate the
effectiveness of the project mitigation plan. Costs associated
with the operational monitoring are provided in Table E.3.47.
(a) Impact Monitoring of Salmon Populations
Salmon populations in the Devil Canyon to Talkeetna reach
will be monitored to determine if populations maintain his-
torical levels during the operation phase. Monitoring will
consist of enumerating returning adults that pass Sunshine
and Curry Stations and monitoring smelt out-migration from
the reach. Adults will be enumerated using the fishwheel
and tag/recapture program currently being used in the base-
line studies. The smelt out-migration will be evaluated
using a smol t trap program such as was conducted in the
Spring 1982 study program.
The results of these studies wi 11 be used to evaluate
changes in the population size, species composition or
changes in stream use patterns of the five Pacific salmon
species. Results of the mitigation monitoring described in
Section 2.6.2 (b) will be used to determine the cause of
changes.
{b) Mitigation Monitoring
Mitigation features to be monitored to evaluate whether any
adequate level of mitigation is being achieved include:
-Sloughs;
Mainstem and side channel salmon spawning areas;
-The resident fisb population provided by the stocking pro-
gram; and
-The fixed-cpne valves designed to avoid gas supersatura-
tion.
E-3-182
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2.6 -Monitoring Studies
The monitoring activity will include evaluating the opera-
tion and maintenance procedures to ensure that the facili-
ties are operating effectively.
If it is determined that a mitigation feature is not meeting
the intended 1 evel of effectiveness s modifications to the
migitation feature will be made to further reduce impacts.
The specific modifications will be made on a site-specific
basis in consultation with the monitoring team.
(i) Monitoring Slough Modifications
The various features incorporated for slough habitat
enhancement wi 11 be monitored to determine whether
they are meeting their intended function and are
operating properly.
Mitigation features designed to all ow adult sal man
access into the sloughs will be annually inspected
after breakup to identify and effect any needed
repairs prior to the adult return. Annual monitoring
of returning adults will identify access problems or
passage delays and appropriate corrective actions as
recommended by the monitoring team will be taken.
Modifications to sloughs designed to maintain spawn-
; ng areas will be annually inspected prior to the
spawning season to verify that the area cant a ins
suitable spawning conditions such as amount of flows
depth of waters and suitable substrate. Areas that
become overly silted will be cleaned. If flows
diminish so that spawning is no longer possible, the
monitoring team will recommend appropriate corrective
action.
The number of spawning adults returning to the
sloughs will be monitored annually to measure changes
in run size to determine if the combination of mini-
mum flow and slough modifications is maintaining
natural production. This monitoring will also serve
to determine whether the capacity of the modified
areas is ·being exceeded. Appropriate remedial
actions, as recommended by the monitoring teams will
be taken when spawning damsites are either too low or
too high.
Fry production wi 11 be monitored annually to verify
incubation success. Fry monitoring will include an
assessment of out-migration timing and success.
E-3-183
2.6-Monitoring Studies
The annual slough monitoring will include an evalua-
tion of general slough conditions including vegeta-
tive encroachment, beaver occupation, and general
condition of the spawning and rearing areas. Appro-
priate remedial actions recommended by the monitoring
team will be performed to maintain slough productiv-
ity.
Following flow regulation, representative sloughs
wi 11 be instrumented with temperature and flow
recording instruments to monitor physical character-
istics of the sloughs throughout the year. Monitor-
ing of the physical processes will be continued until
slough conditions stabilize under the regulated flow
regime. This physical processes monitoring will be
used in part to determine whether further modifica-
tions to the physical habitat must be made to main-
tain slough productivity.
Methods used to evaluate the slough mitigation fea-
tures will be consistent with methods currently being
used to assess baseline conditions of the parameters
to be monitored. Specific study programs wi 11 be
evaluated and approved by the monitoring team prior
to implementation.
(ii) Monitoring of Mainstem and
Side-Channel Spawning Areas
The mainstem and side channel spawning areas that are
provided as mitigation features will be monitored to
quantify adult salmon use of these areas. If the
areas receive the expected level of use, the beds
will be monitored and maintained on an annual basis.
Monitoring methodology will be similar to that cur-
rently used to evaluate mainstem and side-channel
spawning habitats and will include standard physical
and chemical measurements as well as biological
ana lyses.
(iii) Monitoring of Stocked Grayling
and Other Resident Fish
Areas that are stocked with grayling or other res i-
dent fish to compensate for impoundment losses will
be monitored to ensure that the stocking program is
providing a, replacement population of harvestabl e
E-3-184
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2.7 -Cost of Mitigation
fish. The monitoring program will include evalua-
tions of abundance, growth and age structure.
Restockings will be made as needed. If the initially
stocked areas will not support the desired poj)..lla-
tions, additional habitats will be evaluated for
stocking.
( i v) Monitoring of Fixed-Cone Valves
The performance of fixed-cone valves will be evalu-
ated to determine whether gas supersaturation is
being avoided. This monitoring will consist of a
one-time evaluation of gas supersaturation during a
release-to verify that the valves are operating as
designed.
2.7 -Cost of Mitigation
To develop estimates of mitigatinn cost, 1982 cost estimates were pre-
pared for each activity (Tables E3.39, E3.41, E3.45 and E3.47}. These
cost estimates were based upon unit cost information derived from
recent experience in Alaska or upon experience elsewhere and/or
earlier, and escalated to arrive at 1982 cost estimates for south-
central Alaska. Costs for the mitigation program were separated into
construction cost and average annual operating cost. For the major
mitigation activities, these costs are:
Construction Cost
Downstream Mitigation (Table E.3.39}
Impoundment Mitigation (Table E.3.39)
Dam Structure (Table E.3.39)
Water & Fisheries Quality Monitoring
(Table E.3.41)
Aquatic Studies Program (Table E.3.45)
Total Construction Cost
Average Annual Operating Costs
Fisheries Monitoring (Table E.3.47)
Maintenance of Facilities (Table E.3.45)
Total Average Annual Operating Cost
$ 6,380,000
1,315,000
80,100,000
12, 165' 100
6,000,000
$105,960,100
$ 511,400
1,064,000
$1,575,400
These costs do not include any contingency costs or owner's administra-
tive costs.
E-3-185
2.8 -Agency Consultation on Fisheries Mitigation Measures
Three agencies, USFWS, ADF&G, and Alaska Department of Natural Resour-
ces provided comments on fisheries mitigation measures.
2.8.1. -U.S. Fish and Wildlife Service
The USFWS provided formal comments on fisheries
sures on October 5, 1982, and January 14, 1983.
ments are divided into construction-related
operation-related mitigations.
(a) Construction Mitigations
mitigation mea-
The USFWS com-
mitigations and
Construction mitigations primarily concern siting, design,
and scheduling. The comments are:
-Siting and Design
The access road and transmission 1 ine between Watana and ·
Devil Canyon should use the same corridor.
The diversion tunnel should be screened to avoid entrain-
ing fish. The siting of construction and permanent vil-
1 ages and other facilities should be reviewed with the
goal of minimizing impacts.
-Schedul in~
Construction activities and reservoir clearing should
occur in the winter to minimize impacts. Work in aquatic
systems should be scheduled to avoid conflicts with sensi-
tive life history stages.
All of these comments have been addressed in Section 2.4.3.
A design criteria manual and a construction practices manual
are being prepared for the project that will detail the sit-
ing, design, and construction practices criteria that wil1
be used on the project. These manuals will be prepared in
consultation with the agencies. The manuals will include
timing and scheduling based on the identified sensitive
periods and the needs of the construction contractor.
{b) Operation Mitigations
Comments on operation mitigations were divided into those
concerning reservoir mitigations and downstream mitigations.
(i) Reservoir Mitigations
Recommendation:
ties need to be
options include
extension of
access.
Within and out-of-basin opportuni-
examined to offset losses. Possible
stream stocking, lake fertilization,
existing fisheries and increased
E-3-186
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2.8-Agency Consultation on Fisheries Mitigation Measures
Response: The mitigation plan provides for a gray-
ling hatchery and planting program that will intro-
duce grayling into waters in, or in the vicinity of,
the project to compensate for lost grayling habitat
in the reservoirs. The waters to be stocked will be
selected based on a review of water bodies in and
near the project area, in consultation with USFWS,
ADF&G, BLM, and adjacent land owners.
The project facilities and recreation plan will pro-
mote increased access and extension of existing
fisheries.
Recommendation: The viability of a reservoir fishery
needs to be evaluated.
Response: The Watana and Devil Canyon reservoirs
were evaluated in terms.of their suitability as fish
habitat. It was concluded that the drawdown cycle in
the Watana reservoir will limit fish populations and
wi 11 probably not support a quality reservoir fish-
ery. A grayling fishery, however, would develop in,
and at the mouths of, tributaries discharging into
the reservoir. For the Devil Canyon reservoir, it
was concluded that a re.servoir fishery is a viable
option because of the timing and magnitude of draw-
down cycle. The mitigation plans provide for intro-
ducing rainbow trout into the Devil Canyon reservoir,
since this species is expected to utilize both reser-
voir and tributary habitats. This introduction would
extend the range of rainbow trout past De vi 1 Canyon,
but the species would be precluded from entering the
upper basin by Watana dam.
(ii) Downstream Mitigations
Recommendation: Mitigation options for the dewatered
area between the Devil Canyon dam and its powerhouse
need to be considered.
Response: The habitat 1 ost between Devi 1 Canyon dam
and the powerhouse is typified by velocities between
9 and 16ft/sec (2.iand 4.8 m/sec), the substrate is
bedrock. The area is not expected to provide signi-
ficant fish habitat, thus the dewatering of the sec-
tion is not expected to result in substantial im-
pacts. The few chinook that migrate through the
canyon during low water years (such as 1982) wnl be
blocked by the dam. Milling areas will still be
availab1e at the powerhouse outlet. Because of these
factors, mitigation measures are not proposed.
E-3-187
2.8 -Agency Consultation on Fisheries Mitigation Measures
Recommendation: The potential to establish/expand
the salmon fishery between the Devil Canyon and
Watana damsites, in the absence of a Devil Canyon
dam, needs to be addressed.
Response: The flows downstream from Watana Dam are
expected to permit chinook salmon to ascend to
Tsusena Creek, at the base of the dam. If the Devil
Canyon dam is eventually e 1 i mi nated from the p 1 an ned
development, it would be possible to establish a
fishery in this reach. Since Devil Canyon dam is a
part of the present plan, developing these chi nook
stocks for the period between Watana development and
Devil Canyon development is not considered cost-
effective mitigation.
Recommendation: Adjustments to the Watana reservoir
filling schedule to m·inimize impacts to fish resour-
ces should be considered. Addition of a low-level
intake port should be evaluated.
Response: Lengthening the filling period would delay
impacts to grayling but would not reduce these im-
pacts. Lengthening the fi 11 i ng period wou 1 d in-
crease downstream impacts to salmon by increasing the
number of years that returning adults are exposed to
1 ower temperatures during the upstream migration.
Shortening the f·i 11 i ng period may eliminate the tem-
perature impact, but would increase impacts caused by
low flows. It may be possible to achieve a balance
of low flows combined with short-term augmented flows
during the second filling year that would minimize
temperature/flow impacts and fi 11 the reservoir on
schedu 1 e. These opt ions are being evaluated along
with the desirability of a low-level intake port.
Reconunendation: An expanded discussion of the salmon
hatchery mitigation option should be provided.
Response: The salmon hatchery mitigation option is a
low priority compensation alternative. It is antici-
pated that the proposed mitigation will maintain
salmon po~lations in the historical locations and
that a hatchery will not be needed. Nevertheless, a
hatchery siting study has been completed (Kramer,
Chin and Mayo, Inc. 1983).
Recommendation: Slough modifications to increase
fish habitat need to be demonstrated.
E-3-188
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2.8-Agency Consultation on Fisheries Mitigation Measures
Response: Investigations into the maintenance of
salmon spawning habitat in sloughs is continuing as
part of the design studies.
2.8.2 -Alaska Department of Fish and Game
The Alaska Department of Fish and Game (ADF&G) provided comments
on mitigation measures on July 27, 1982 and January 13, 1983.
The ADF&G comments related to mitigation of lost grayling habitat
and mitigation for alterations to downstream salmon habitat.
Recommendaton: Hatchery propagation of grayling in Alaska is not
well developed at present and grayling production in Alaska must
be considered experimental.
Response: It is recognized that grayling propagation is not well
developed. The mitigation plan provides for a three-year experi-
mental phase to develop grayling propagation technology that will
have utilization beyond project needs. Since ADF&G intends to
develop grayling propagation techniques and the Power Authority
has a need for such technology, a cooperative experimental effort
would be desirable.
Recommendation: In stream flows and temperatures required to
maintain present populations should be carefully evaluated to
provide a basis for further migration measures.
Response: The ongoing studies are addressing these concerns and
substantial analysis will be available on June 30, 1983. These
will be further analyzed during refinement of the mitigation
plan.
Recommendation: If onsite mitigation of fisheries impacts cannot
be accomplished, hatcheries should be considered.
Response: The salmon hatchery option is a low priority compensa-
tion alternative. It is anticipated that onsite mitigation will
be effective at maintaining production of slough and mainstem
spawning salmon. Nevertheless, a hatchery siting study has been
completed {Kramer, Chin and Mayo, Inc. 1983).
Recommendation: Results from the ADF&G study on the salmon en-
hancement potential of the upper Susitna River without the pro-
ject should be included in the discussion of mitigation options.
Response: The study had not been received by the time this
document went to press.
E-3-189
2.8-Agency Consultation on Fisheries Mitigation Measures
2.8.3-Alaska Department of Natural Resources
The Alaska Department of Natural Resources• comments of January
13, 1983, requested that downstream mitigation, other than slough
modifications, be included. The discussion of downstream
mitigation has been substantially revised to indicate more
clearly that a series of habitat enhancement techniques will be
undertaken, rather than construction of an artificial spawning
channel. Also, enhancement of mai nstem spawning habitats wi 11
provide new habitat in previously unutilized areas.
E-3-190
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3 -BOTANICAL RESOURCES
3.1 -Introduction
The object of this report is to describe the existing botanical
res au rces of the Su sitna Basin; the impacts which the Su sitna Hydro-
electric Project will produce on those resources; and mitigative
measures incorporated by the project to avoid, minimize, rectify,
reduce, or compensate for the predicted adverse impacts. As stated in
Section 1.2, the primary importance of botanical resources within the
project area is their key role as components of wildlife habitat. The
following discussions have been coordinated closely with baseline
descriptions, impact assessments, and mitigative measures presented in
Section 4 (Wildlife), and form an important basis for that section.
A diversity of plant co111111.1nities occurs within the study area desig-
nated for botanical resources and wildlife of the Susitna Hydroelectric
Project. The study area (Figures E.3.32 through E.3.35) includes the
watershed of the Susitna River upstream from Gold Creek; a corridor
extending approximately 1 mile (1.6 km) to each side of the downstream
floodplain between Gold Creek and Cook Inlet; corridors approximately 5
miles (8 km) in width encompassing the transmission routes from Healy
to Fairbanks and .. Willow to Anchorage; and the intertie transmission
corridor from Willow to Healy, with a study area varying from approxi-
mately 4 to 18 miles (6.4 to 28.8 km} in width (Conmonwealth Assoc.
1982).
In this report, the entire Susitna Basin has been subdivided into three
component drainage basins: the upper, middle, and lower basins. These
areas are delineated in Figure E.3.3, and the designations are used
consistently throughout the discussions of botanical resources and
wildlife (Exhibit E, Chapter 3, Sections 3 and 4, respectively).
However, because the watershed of the Susitna River upstream from Gold
Creek, at River Milepost (RM) 136.8 (Figure E.3.33), was distin9Jished
for study purposes from the downstream fl oodpl ai n · study corri dar
(Figure E.3.34), data were evaluated separately for these two areas in
certain cases. In these cases, the entire basin area upstream from
Gold Creek is defined as the Watana and Gold Creek watersheds, as shown
in Figure E.3.36. Data presented collectively for the Watana and Gold
Creek watersheds therefore include all of the upper basin and all of
the middle basin except that portion downstream from Gold Creek. The
latter area is represented in the downstream floodplain study
corridor.
Unless cited otherwise, the descriptions that follow are from
McKendrick et a 1. ( 1982). Vegetation types are characterized in accor-
dance with the terminology of Viereck and Dyrness (1980). Common names
of plant species appear in the text; their scientific names are shown
in Appendix ED. Species and varieties under--review by the USFWS for
official designation as endangered or threatened are referred to by
scientific nomenclature in the text.
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3 -BOTANICAL RESOURCES
3.1.1-Regional Botanical Setting
The Su sitna River system drains parts of the Alaska Range to the
north and parts of the Ta"lkeetna Mountains to the south. The
vegetation communities of the region are typical of those cover-
; ng vast areas of Alaska and northern Canada. They include
forest and shrub communities on stream floodplains; coniferous
and deciduous forests on canyon slopes adjacent to the flood-
plains; shrub communities, conifer stands, and tundra on benches
above the canyon slopes; and tundra at higher elevations (Figure
E.3.38). River action and fires contribute greatly to the
ever-changing mosaic of plant communities and successional stages
within the region.
Predominant vegetation of the lower mountains and lower slopes of
the higher mountains in the project area is alpine tundra as
classified by Viereck and Dyrness (1980). Some areas mapped as
rock have pioneering species growing in crevices, but the plants
provide negligible ground cover. These habitats are common in
mou nta·i nou s areas throughout Alaska. Permanent snowfields and
glaciers are found at higher elevations of the Susitna watershed
in the Alaska Range.
The benches bordering the middle basin portion of the Susitna
River and the area around the Mac 1 aren River are moist tundra.
This type includes herbaceous meadows as well as shrub-dominated
sites, both of which are widespread in Alaska, especially in
the Brooks Range, on the Seward Peninsula, and near the Killuck
Mountains.
Along east-west reaches of the Susitna River in the middle basin,
steep canyon slopes and some adjacent areas are covered with
closed spruce-hardwood forest (Viereck and Dyrness 1980). This
type of vegetation is most common along rivers in the
south-central and interior regions of Alaska.
Vegetation north of the Susitna River to the Denali Highway
along portions of the Seattle, Brushkana, and Deadman Creek
drainages is variously composed of mat and cushion tundra,
sedge-grass tundra, low shrub types with birch and willow
predominant, and alder-dominated tall shrub.
The southeast portion of the middle basin has extensive flat
areas covered by low shrubland and woodland conifer communities.
The flats in the lower Oshetna River and Lake Louise area are
spruce woodland (Viereck and Dyrness 1980).
Each of the transmission corridors crosses several vegetation
types. The Healy-to-Fairbanks transmission corridor includes
ridges, wet flatland, and rolling hills with areas of open
spruce, open deciduous, and mixed forest; shrublands; and wet
E-3-192
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3 -BOTANICAL RESOURCES
tundra. The Willow-to-Anchorage transmission corridor passes
through closed birch forest, mixed conifer-deciduous forest, wet
sedge-grass marshes, and open and cl a sed spruce stands. The
Willow-to-Healy intertie corridor traverses a variety of vegeta-
tion types, from closed spruce-hardwood forests in the south to
tundra and shrubland in the north.
3.1.2-Floristics
Floristics surveys were made in the Susitna Basin and intertie
corridor by McKendrick et al. ( 1982} and Commonwealth Assoc.
(1982}, respectively. These provided information on the numbers
and distribution of plant species which occur within portions of
the project area.
The following floristics data are summarized from McKendrick et
al. (1982) and Commonwealth Assoc. (1982}, where further details
may be found.
(a) General
In the region including the Watana and Gold Creek water-
sheds, the downstream floodplain, and the intertie corridor,
295 vascular plant species belonging to 151 genera and 57
families were identified (McKendrick et al. 1982} (Appendix
30). Two hundred fifty-five species were identified in the
Watana and Gold Creek watersheds, and 76 species downstream
from Gold Creek.
Plant families in the Watana and Gold Creek watersheds
having the most represented species were the Compositae
(Asteraceae), Salicaceae, Rosaceae, Gramineae (Poaceae),
Cyperaceae, and Ericaceae. Within the non-vascular flora,
11 genera of lichens (including at least 12 species) and 7
taxa of mosses were identified in these areas.
The downstream floodplain flora was predominantly. a subset
of the Watana and Gal d Creek watershed flora. Of the 76
plant species found downstream from Gold Creek, 54 also
occurred in upstream areas. Downstream sites were confined
to the floodplain, which reduced the number of habitats
reprsented and floristic variability relative to the
upstream area. Also, the larger study area and greater time
spent in sampling the Watana and Gold Creek watersheds may
in part account for the 1 arger number of s pee i es found
there.
In the intertie corridor from Willow to Healy, Commonwealth
Assoc. (1982) identified 128 species of vascular plants.
Al1 but 18 of these species were also found in the Watana
and Gold Creek watersheds by McKendrick et al. (1982)
(Appendix 30). Floristics surveys will be conducted in the
Willow-to-Cook Inlet and Healy-to-Fairbanks transmission
corridors in 1983.
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3 -BOTANICAL RESOURCES
(b) Range Extensions
McKendrick et al. (1982) found 22 vascular plant species in
the Watana and Gold Creek watersheds and 9 in the downstream
floodplain corridor which were outside their reported ranges
(see Hulten 1968) (Table £.3.48). However, the Susitna
River drainage upstream from Gold Creek is not well repre-
sented in existing plant collections, and range extensions
may be expected from any additional botanical surveys in the
area.
Two species found in the Watana and Gold Creek watersheds--
Sheldon groundsel and timber oatgrass--represent appreciable
range extensions. Sheldon groundsel had not been officially
reported in Alaska previously, except as possibly present in
the Skagway area. Timber oatgrass had been reported only in
1 ocations near upper Cook Inlet and near Skagway (Hu 1 ten
1968).
In August, McKendrick et al. (1982) found a single specimen
of Sheldon groundsel in a mesic (moderately wet) midgrass
community near upper Portage Creek. Its identity has not
yet been verified. Timber oatgrass was identified in August
in the grass portion of a mosaic of low birch and grass
communities between the Maclaren River and the Denali
Highway.
Two other plant occurrences of note were reported by
McKendrick et a 1. (1982). Rabbi ns pondweed, a submerged
rooted aquatic, was found in Watana Lake (Figure £.3.36).
There has been limited collection of this species in Alaska.
Hu lten ( 1968) reported it from Summit vi 11 age south of
Healy, and Welsh (1974) indicated that it is known from
south-central Alaska, but is evidently rare. Black spruce,
one of the most common trees found by McKendrick et al.
(1982) in the middle Susitna Basin, had been reported by
Hulten (1968) to be in areas north and south of the middle
Susitna River dra·inage, but not in the drainage. Viereck
and Little (1972), however, did include the Susitna drainage
·in their distr'ibution map of this plant.
Most other range extensions reported by McKendrick et a 1 ."
(1982) in the Watana and Gold Creek watersheds were less
noteworthy. Most were extensions to the north (more inland)
from their previous observations. For example, white
bog-orchis had previously been found only near the coast in
Alaska. Northern bog-orchis and sweet gale extensions
involved sites between areas that were previ au sly included
in their ranges. Two-flower cinquefo-il and Kane lousewort
extensions were south of their previously reported ranges.
E-3-194
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3 -BOTANICAL RESOURCES
In the downstream floodplain corridor, McKendrick et al.
(1982) found nine species outside their ranges as reported
by 1-Ulten (1968) (Table E.3.48). One of these, raspberry,
though not reported to extend into the region by Hulten
(1968), was reported by Viereck and Little (1972) to occur
there. Devil•s club showed a slight range extension
upriver. Small-fruit bu 11 rush had previously been found
only in four areas outside southeast Alaska. An unverified
specimen which appeared to be Chamisso•s arnica represented
a 1 arge extension from the Alaska Peninsula and southeast
Alaska. The presence of enchanter• s nightshade was an
extension inland from coastal regions. Sweet-scented
bedstraw and thinleaf alder were minor extensions, and
baneberry and northern blackcurrant were extensions from the
surrounding areas into the basin.
It is again emphasized that many of the range extensions
reported above were merely the result of more intensive
botanical collections by McKendrick et al. (1982) than had
been made previously and did not represent plants growing in
unexpected environments.
3.1.3-Contribution to Wildlife, Recreation,
Subsistence, and Commerce
In the Susitna watershed as elsewhere, botanical resources make
essential contributions to human activities and land uses. Vege-
tation is necessary for the regional maintenance of surface water
and ground water quality through water retention, determination
of physical and chemical soil properties, and erosion control.
Botanical resources are also essential as fish and wildlife habi-
tat components. The structure and productivity of plant communi-
ties are requisite the occurrence and abundance of wildlife
species within the project area, as discussed further ·in Section
4 (Wildlife). Wood is used by local residents for building and
heating homes. In addition, the mosaic of plant comrrunities and
successional stages provides an important aesthetic contribution
(Exhibit E, Chapter 8). Thus, botanical resources directly
support all of the limited human activities and land uses of the
project area (Exhibit E, Chapters 5, 7, and 9).
Commercial use of plant resources within the project area has
been limited to small logging operations along the Susitna River
floodplain in the lower basin (ADNR 1982b). Vegetation of the
upper and middle basins is almost entirely u..ndisturbed. Timber
sales are planned for portions of public lands within management
units of the Matanu ska-Su sitna-Beluga Cooperative Planning
Program (ADNR 1982b). Lands with highest forestry potential
within the project area are 1 ocated along nearly the entire
length of the Susitna River floodplain downstream from the
confluence with Po rage Creek. Eleven timber sa 1 es tot a 11 i ng
E-3-195
3 -BOTANICAL RESOURCES
approximately 325,100 acres (131,619 ha) within the lower basin
are planned by the Alaska Department of Natural Resources and
Matanuska-Susitna Borough; most are scheduled to begin no earlier
than 1992 (ADNR 1982b).
3.2 -Baseline Description
3.2.1-Threatened or Endangered Plants
At present, no endangered or threatened plant taxa are officially
listed for Alaska by federal or state authorities; however, 37
plant taxa are currently under review by the U.S. Fish and
Wildlife Service (1980a) for possible protection under the
Endangered Species Act of 1973. ivtlrray (1980) discusses the
habitats, distributions, and key traits of most of the Alaskan
candidate taxa. Searches for these plants were made in two
areas--the Watana and Gold Creek watersheds (Figure E.2.36)
(McKendrick et al. 1982) and the intertie transmission corridor
between Willow and Healy (CoiT1llonwealth Assoc. 1982) (Figures
E.3.35 and E.3.37.
No surveys of candidate taxa were conducted in the downstream
floodplain corridor or the transmission corridors from Healy to
Fairbanks and Willow to Anchorage. Changes in downstream water
flow caused by the project are judged unlikely to affect any
endangered species, because none of them (Table E.3.49) is nor-
mally found in association with river floodplains. Endangered
plant surveys will be conducted along the Healy-to-Fairbanks and
Willow-to-Anchorage transmission corridors in 1983.
(a) Watana and Gold Creek Watersheds
Table E.3.49 shows the plant taxa on Murray•s (1980) list
believed most likely to occur in the Susitna River drainage
and in the habitats to be affected by canst ruction of the
proposed dams and associated facilities. McKendrick et al.
( 1982) conducted ground searches for these candidate taxa
in the following areas of the Watana and Gold Creek water-
sheds: (1) alpine areas near the Susitna and West Fork
Glaciers; (2) lowlands of the upper and middle basins, in-
cluding those of the Maclaren and Tyone Rivers and their
associated ridges, terraces, and periglacial features; (3)
calcareous outcrops and promontories along the Susitna River
near Watana and Kosina Creeks; (4) potential alternative
access routes in the middle basin; and (5) borrow sites
planned for dam construction. These areas were selected
after reviewing the 1 iterature pertaining to the 1 ikely
habitats of endangered plant taxa, conferring with special-
ists in Alaska plants, and conduct-ing discussions with
project geologists to identify calcareous soils (a habitat
component of some of the species in question).
E-3-196
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3 -BOTANICAL RESOURCES
(b)
Well-drained rocky or scree slopes were searched in alpine
areas of the upper drainage basin in the steep valleys adja-
cent to the Su sitna and West Fork Glaciers. None of the
taxa under federal review was found.
Well-drained, sandy or gravelly ridges and terraces in low-
lands of the upper and middle drainage basins were searched.
Shores of lakes and ox-bow ponds, and peri-glacial features
were emphasized. A trip was made downstream as far as Devil
Canyon, and two 1 arge gravel bars within the riverbed were
surveyed. None of the taxa under federal review was found
in these lowland surveys.
Several of the taxa listed by Murray (1980) were known cal-
ciphiles (plants that normally grow on calcareous soils).
Three locations with calcareous soils were found in the
project area. One was on the northwest flank of Mt. Watana
at about 3700· ft (1128 m) elevation, another on the squth
side of the Su sitna River immediately east of its confluence
with Kosina Creek, and the third was on the north side of
the Susitna River about 4.5 m"iles (7 km) west of Watana
Creek. Calciphilic plants were found on two of these sites,
but none of those found was listed by Murray (1980).
Three sites judged by substrate characteristics potentially
to support rare plants were searched along the proposed
access route section from the Denali Highway to Watana
(Figure E.3.37). One site was a sandy blowout area on the
northwest side of Deadman Mountain; one was a series of dry
ridges (probably glacial moraines or terraces) on the south
side of Deadman Mountain; and one was an area of windblown
ridges on the east side of Deadman Mountain. No candidate
threatened or endangered taxon was found at any of these
sites, nor along any of the other proposed access corri-
dors.
Vegetation in the vicinity of borrow sites proposed for dam
construction {Figure E.3.37) was surveyed in July 1981. No
candidate threatened or endangered taxon was found.
Willow-to-Healy Intertie
The Willow-to-Healy intertie corridor {Figures E.3.35 and
E.3.37 was surveyed for the presence of Smelowskia borealis
var. vill osa, Taraxacum carneocol oratum, and Mont1 a
bostockii, all of which appear on Murray•s {1980) list
{Table E.3.49). Geologic and topographic maps were used to
identify potential habitat areas for these taxa within the
intertie corridor. None of the candidate taxa was found in
the locations surveyed (Commonwealth Assoc. 1982).
E-3-197
3 -BOTANICAL RESOURCES
(c) Summary
In summary, the Susitna River watershed upstream from Gold
Creek was surveyed at selected habitat sites for plant taxa
under consideration for threatened or endangered status.
Access routes, borrow areas, and the intertie corridor were
also surveyed for the presence of these taxa. No candidate
threatened or endangered plants were found. Further endan-
gered plant surveys will be made in the Healy-to-Fairbanks
and Willow-to-Anchorage transmission corridors in 1983.
3.2.2 -Plant Communities
(a) Methods
Vegetation of the project area was mapped at three different
scales by McKendrick et al. (1982), using photo-interpre-
tation of high-altitude (U-2) color infrared photographs and
LANDSAT imagery, followed by confirmation of vegetation
types in the field. Plant communities were classified in
accordance with Viereck and Dyrness (1980). The Watana and
Gold Creek watersheds (Figure E.3.36) were mapped at a scale
of 1:250,000 (Figure E.3.38). The middle basin (Gold Creek
to the Tyone River, RM 246.5) was further mapped at a scale
of 1:63,360, encompassing land bordering the Susitna River
to a distance of about 10 miles (16 km) and thus including
all of the construction and borrow areas associated with the
proposed Watana and Devi 1 Canyon dams, a 11 of the Watana-
to-Devi 1 Canyon and Devi 1 Canyon-to-Gal d Creek access and
transmission routes, and approximately the southern one
third of the Denali Highway-to-Watana access route and
associated borrow areas {Figures E.3.39, E.3.40, and
E .3 .41). The Healy-to-Fairbanks and Wi 11 ow-to-Anchorage
transmission corridors were also mapped at a scale of
1:63,360 (Figures E.3.48 through E.3.52). Vegetation maps
of the intertie corridor, presented at a scale of 1:250,000
in Commonwealth Assoc. ( 1982), were adapted from a map
previously prepared by the Joint Federal-State land Use
Planning Commission for Alaska (1973) and adapted
subsequently by the U.S. National Park Service (1976).
McKendrick et al. (1982) prepared vegetation maps of the
Watana and Devil Canyon impoundment, construction, and
borrow areas, and the Susitna floodplain downstream to
Talkeetna, at a scale of 1:24,000 (Figures E.3.53 through
E.3.65). Wetland vegetation types were mapped by McKendrick
et al. (1982) at a scale of 1:24,000 from the Oshetna River
to the Devil Canyon damsite, using the system of Cowardin et
al. (as adopted by the Fish and Wildlife Service {1980b).
(Figures E.3.66 through E.3.73. The wetlands maps were
based on the 1:24,000-scale vegetation maps.
E-3-198
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3 -BOTANICAL RESOURCES
Whereas the vegetation maps show definite boundaries between
vegetation types, such lines of demarcation do not exist in
the field and are imposed by the judgment of the carto-
grapher. Another consideration is that the small est feas-
ible units mappable at the 1:250,000, 1:63,360, and 1:24,000
scales are about 642 acres (260 ha), about 40 acres (16 ha),
and about 7 acres (3 ha), respectively. Therefore, vegeta-
tion types shown on the larger scale maps and tables derived
from them ar·e sometimes absent from the smaller seale
mapping and tables (McKendrick et al. 1982).
The cl assi fi cation system proposed by Viereck and Dyrness
(1980) is a hierarchical system based on the characteristics
of the vegetation itself. -It is composed of four formations
for terrestrial vegetation: forest, tundra~ shrubland, and
herbaceous vegetation; and one formation for aquatic vegeta-
tion. These formations constitute Level I of the classifi-
cation system. At the finest level of re~:olution (Level V),
units are discrete plant comnunities. Levels II, III, and
IV are intermediate in resolution. In most cases, the Level
III names were used for mapping; however, Level IV names
were used for forested areas on the 1:24,000 and
1:63,360-scale maps. A total of 19 categories were used to
map vegetation at the 1:250,000 sccle; 25 were used on the
1:63,360-scale maps; ~nd 21 were used on the 1:24,000-scale
maps.
Vegetation studies by McKendrick et al. (1982) were
conducted during the> summers of 1980 and 1981. The stuEly
area during 1980 included the Watana and Gold Creek
watersheds and the flocdplain of the Susitna River from Gold
Creek to Talkeetna. [)Jring 1981, the Jownstream floodplain
received further attention, and the Healy-to-Fairbanks and
Willow-to-Anchorage transmission corridors were mapped, in
addition to further surv~:::~'S upstream from Gold Creek. As
shown in Figure E.3.33, areas closer to or including the
proposed impoundment, dam, and ancillary facility locations
were mapped at progressively larger scales, reflecting the
relative extents of direct disturbance expected to result
from the project in these areas {McKendrick et al. 1982).
For confirmation of mapped vegetation types, high-altitude
(U-2) color photography at a scale of 1:120,000 with
overlays of delineated vegetation units was taken into the
field. More attention was given in the field to the areas
mapped at larger scales {i.e., greater resolution), but
locations throughout the entire study area were checked to
include as many reprsentative terrain types and physio-
graphic areas as feasibile. Ground-truth surveys
E-3-199
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3 -BOTANICAL RESOURCES
emphasized vegetation types which were especially difficult
to interpret from aerial photography (McKendrick et al.
1982). During field checking of the Healy-to-Fairbanks and
Willow-to-Anchorage transmission corridors, color infrared
photographs at scales of 1:63,360 and 1:120,000, black and
white 1:48, 000-sca 1 e prints, and 1: 12, 000-sca 1 e true-co 1 or
photographs were variously used (McKendrick et al. 1982).
Additional vegetation mapping of the project area utilizing
recently available real-color and color infrared aerial
photography is currently planned. This mapping has three
objectives: (1) to provide a quantifiable data base for
precise type and areal extent of moose browse within the
Watana and Gold Creek watersheds; {2) to delineate
vegetation comrrunities characteristic of wetlands (as
defined by Cowardin et al. 1979) to a level of detail that
will usefully sopport facility siting and design as well as
preparation of permit applications required by Section 404
of the Clean Water Act; and {3) to provide general mapping
of vegetation types based on improved aerial imagery as a
data base for refined impact assessment and design support.
The mapping program will provide two vegetation map
products: a detailed 1:24,000-scale map of wetland vegeta-
tion and moose browse types delineated to classification
Level IV of Viereck, Dyrness, and Batten (1982); and a
1:63,360-scale map of vegetation types delineated to classi-
fication Level III of Viereck and Dyrness {1980). The
1:24,000-scale map will cover lands in the immediate project
vicinity including all potential impact areas: the impound-
ments, damsites, borrow sites, construction camps and vil-
lages, access corridors, and the Watana-to-Gold Creek trans-
mission corridor. The 1:63,360-scale map will cover the
Watana and Gold Creek watersheds including the access
corridor to the Denali Highway.
Both vegetation maps will be field-checked following initial
photointerpretation with subsequent refinements. .The
1:24,000-scale map will provide categorized detail for moose
browse and wetland vegetation beyond the 1 imits of the
photography, based on field data. Applications of these
maps to impact assessment and mitigation planning are dis-
cussed in Sections 3.3, 3.4, and 4.4. It is expected that
prelim·inary mapping will be available by June 30, 1983.
E-3-201
3 -BOTANICAL RESOURCES
Methods used for the qualitative and quantitative character-
; zat ion of vegetation types are described in detail by
McKendrick et al. (1982). The 64 locations and associated
vegetation types surveyed in the Watana and Go 1 d Creek
watersheds during the summer of 1980 are indicated in Table
E.3.50 and Figure E.3.74.
At these locations, plant species composition and community
structure determinations were made; and data on elevation,
slope, aspect, and landform also were gathered to relate to
plant species composition.
The cover contributed by each plant species was measured
within a series of vertical layers as percent area of each
layer. The ground layer was defined to be all herbaceous
and woody species less than 1.6 feet {0.5 m) tall. The
shrub 1 ayer included woody species taller than 1. 6 feet
(0.5 m) with a diameter at breast height (dbh) less than
1 inch (2.5 em). The understory layer consisted of woody
species between 1 inch (2.5 em) and 4 inches (10.0 em) dbh.
Overstory vegetation contained species larger than 4 inches
{10.0 em) dbh. This classification approach is used here to
describe the vertical layering within plant comrrunities of
the project area.
Forest comrru niti es were defined as those with at 1 east 10
percent cover by tree species regardless of tree height.
Shrubland comrrunities had at least 25 percent cover of
erect-to-decumbent shrubs but were not 1 ocated beyond the
elevational limit of trees. Tundra stands were those com-
munities above or beyond the elevational limit of trees and
were dominated by shrub or herbaceous species.
Forests were divided into subtypes according to the dominant
trees (conifer, deciduous, or mixed). Deciduous and coni-
fer types had at least 75 percent of the tree cover provided
by either deciduous or coniferous trees, respectively.
Mixed types had smaller percentages of each. It shou 1 d be
noted that white and black spruce and common juniper were
the only coniferous species in the study area.
Each forest subtype was further classed as woodland, open,
or closed, depending on percent of tree canopy cover. The
woodland type stands contained between 10 percent and 25
percent tree cover. Open stands contained 25 to 50 percent
tree cover, and closed stands had over 50 percent tree
cover.
E-3-202 r---,
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3 -BOTANICAL RESOURCES
Shrub comrrunities were classed as open or closed by percent
cover, open indicating up to 50 percent cover. Shrub vege-
tation was also classed as tall or low, with tall shrub
d i sti ngu i shed primarily by the presence of Sitka alder fre-
quently 6 to 12 feet (2 to 4 m) in height.
Low shrub comrrunities were about 3 to 5 feet (1 to 1.5 m)
tall and were classified into three subtypes: those domi-
nated by birch, willow, and a mixture of the two. Resin and
dwarf arctic birch were the predominant birches; and willows
were typically represented by such species as diamondleaf
and feltleaf willow, both important as moose browse.
Aquatic vegetation within the Watana and Gold Creek water-
sheds was examined during August 1980. In order to obtain
site-specific information on aquatic plant species, 24 sel-
ected ponds and lakes and their adjacent uplands were sur-
veyed on foot from Devil Canyon (RM 152) to the confluence
of the Susitna and Oshetna Rivers (RM 233) (Figure E.3.75).
During the surveys, species composition, dominance, and
tot a 1 cover ( re 1 at i ve to the amount of water) were
estimated. Elevation, estimated rooting depth, and width of
surrounding wetland area were recorded. Surrounding wetland
was limited by definition to the Lacustrine-L imnetic-
Emergent Wetland-Vascular wetland class of Cowardin et al.
( 1979} ~ Many remaining ponds and 1 akes were examined by
helicopter overflights.
Quantitative descriptions of downstream floodplain plant
communities were made during the summer of 1981 at the 29
1 ocat ions shown in Figure £.3 .34. Vegetation cover by
species was measured along transects. Density of woody
species was determined by counting individual stems of
plants within specific height ranges growing inside desig-
nated measurement plots. Age, height, and diameter at
breast height (dbh) of low shrubs, tall shrubs, and trees
were measured for randomly selected plants along the tran-
sects, and the age of each measured tree or shrub was deter-
mined by counting growth rings taken from cross-sectional
cuttings or cores. Crown dominance, a measure of which
species within a stand were capturing the canopy sunlight,
was evaluated as follows: (1) open growth (not encoun-
tered), (2) dominant-received sunlight from above and the
sides, (3) codominant -received sunlight from above, but
not from the sides, (4) intermediate -plant barely reached
main canopy, (5) overtopped-plant was below general level
of canopy, (6) subordinate -below the overtopped category,
and (7) ground -the lowest level. The ground elevation of
each floodplain stand relative to river surface elevation
was measured by rod-and-level technique at two or three
E-·3-203
3 -BOTANICAL RESOURCES
different times during the summer of 1981. Time of day for
each measurement was recorded for later reference to rate of
river flow.
(b) Watana and Gold Creek Watersheds
Figure E.3.38 shows the general distribution of vegetation
in the Watana and Gold Creek watersheds, and Figures E.3.39
through E.3.41 and E.3.53 through E.3.65 provide greater
detail. Table E.3.50 and Figure E.3.74 indicate field
sampling locations and associated vegetation types
characterized for ground truth and floristics during June,
July, and August 1980 (McKendrick et al. 1982). Hectares
and percentages of total area covered by vegetation types in
the Watana and Gold Creek watersheds are shown in Table
E.3.51, based on mapping at a scale of 1:250,000 (Figure
E.3.38) (McKendrick et al. 1982). Table E3.52 shows
hectares and percentages of total area covered by vegetation
types in the 10-mil e (16-km) area on each side of the
Susitna River from Gold Creek to the Maclaren River, based
on mapping at a scale of 1:63,360 (Figures E.3.39 through
E.3.41 (McKendrick et alo 1982).
The structure and distribution of vegetation types at eleva-
tions below tundra in this area are strongly influenced by
past fires, evidenced by fire scars on the trees. Post-
fire succession for b 1 ack spruce stands typically proceeds
from the initial herbaceous and shrubby stages to young
black spruce stands to dense and finally decadent black
spruce/moss communities (Van Cleve and Viereck 1981). Post-
fire succession in white spruce stands includes the initial
herb and tree seedling stage; the shrub-tree sapling stage;
and the dense hardwood stage of aspen, birch, or a mixture
of aspen and birch. From this point the stand proceeds
through a mature hardwood-spruce seedling stage, a mixed
white spruce-hardwood stage, and finally a mature white
spruce stage (Van Cleve and Viereck 1981). Most of the
herbaceous, shrubby, deciduous, and mixed forest convrunities
identified and described below may be successional stages in
the process of transition to black or white spruce forest.
(i) Forests
Forest vegetation types were located at lower eleva-
tions and covered approximately 21 percent total area
(860,481 acres, 348,232 ha) of the Watana and Gold
Creek watersheds. The mean elevation of forest areas
sampled was 1716 feet (523 m) (range 1100 to 2600
feet, 340 to 790 m).
E-3-204
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3 -BOTANICAL RESOURCES
Forested comrrunities in this area were similar to
those described by Viereck (1975). Black spruce
generally occurred on wetter sites than white spruce,
and both spruce species occurred on colder sites than
those of deciduous or mixed forests. Black spruce
forests on poorly drained soils are discussed as
wetlands ·in Section 3.2.3. Closed forests occur on
sites warmer than those of open forests. Deciduous
and mixed forest stands in the project a rea were
considered earlier successional stages of the conifer
stands (Viereck 1970, 1975; Hettinger and Janz 1974).
-Coniferous Forest
Coniferous forests covered approximately 19 percent
total area (760,045 acres; 307,586 ha) in the
Watana and Gold Creek watersheds and consisted of
spru.c.e stands with a majority of either white or
black spruce. These forests contained a well-
developed ground layer with a high percent cover
(94 percent) (Tables E.3.53 through E.3.56). The
layering structures of white and black spruce
stands were similar, except that white spruce
stands usually had a greater overstory cover (35
percent compared to 14 percent), a reflection of
the generally larger cover area of individual
mature white spruce trees (Tables E.3.54 and
E.3.55).
As evident in Tables E.3.54 and E.3.55, open white
·spnJce and black spruce stands differed greatly
with respect to species composition and percent
cover contributed by the two spruce species within
the vertical strata. In the open white spruce
stands sampled, black spruce was absent; whereas in
the open black spruce stands, total black spruce
cover (22 percent) and white spruce cover (17 per-
cent) were nearly equal. White spruce percent
cover ( 13 percent) was greater in the overstory
layer because of the larger cover area of individ-
ual white spruce trees as compared to black spruce
(5 percent cover) which had reached the overstory.
Core sampling indicated that large white spruce
ranged from 34 to 78 years in age and large black
spruce from 77 to 171 years. Several white spruce
stands examined appeared to be recovering from past
disturbance, perhaps fire; black spruce stands
showed less signs of disturbance.
E-3-205
3 -BOTANICAL RESOURCES
Open spruce stands were usually found on riverine
slopes or terraces at elevations averaging 1600
feet (487 m) (range 1100 to 1950 feet; 340 to
590 m) and covered approximately 1 percent of the
total area. The cover contributed by the white
spruce trees was concentrated in the overstory
1 ayer (35 percent overstory, 1 percent shrub),
whereas percent cover provided by black spruce
trees was proportionately greater in the shrub
layer (5 percent overstory, 8 percent shrub)
(Tables E.3.54 and E.3.55). Canopy cover of the
ground 1 ayer in open spruce forests normally
exceeded that of the overstory. Black spruce
stands contained 1 ow shrubs, such as crowberry,
northern Labrador tea, bog blueberry, and mountain
cranberry, in the ground layer. Bluejoint was the
predominant ground 1 ayer species by cover in open
white spruce stands.
Cover of feather mosses in open stands of both
white and black spruce approximated that of the
trees. Low shrubs, such as crowberry, northern
Labrador tea, bog blueberry, and mountain cran-
berry, accounted for rruch of the woody ground layer
in open black spruce stands (Table E.3.55). Pre-
dominant herbaceous species common to both types of
open stand were twinflower and horsetails.
All woodland spruce stands surveyed by McKendrick
et al. ( 1982) were black spruce. This was the most
widespread forest type and covered approximately 12
percent of the total area of the Watana and Gold
Creek watersheds. Unlike open spruce forest,
woodland stands were composed of scattered, stunted
trees, and the overstory was almost negligible
(Table E.3.56). This vegetation type was usually
found on relatively level benches with poorly
drained soils at elevations averaging 2,046 feet
(range 1600 to 2600 feet; 490 m to 740 m). The
trees were usually too small to qualify for the
overstory layer because trunks were generally less
than 4 inches {10 em) dbh. In woodland spruce
stands, sphagnum mosses, not feather mosses, were
the most predominant cover species {62 percent
cover); other important ground layer species
included sedges, woodland horsetail, and low shrubs
similar to those found in the open spruce stands
(Table E.3.56).
E-3-206 )~\
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3 -BOTANICAL RESOURCES
Balsam poplar is the first tree to appear during
successional develoJlllent of vegetation an allurial
deposits. Balsam poplar trees provided about 75
percent cover in the overstory, but contributed
relatively small cover (5 percent) within the
understory and shrub layers of balsam polar stands
(Table E.3.57).
Closed paper birch stands occurred on steep,
usually south-facing slopes that had typically been
subjected to recent disturbance, as described by
Hettinger and Janz (1974) for northeastern Alaska.
The layer structure was similar to that of closed
balsam poplar stands--73 percent overstory cover, a
well-developed ground layer (95 percent cover), and
relatively minor cover in the shrub and understory
layers (3 and 9 percent, respectively) (Table
E.3.58). Frequently the overstory contained a few
scattered white spruce.
Trembling aspen stands were infrequently found on
the upper portions of quickly · draining, dry,
south-facing slopes. Their general structure was
similar to that of other closed deciduous stands in
that there were well-developed overstory and ground
layers (80 and 85 percent, respectively), but
poorly developed shrub and understory 1 ayers (5
percent for both) (Table E.3.59).
-Mixed Conifer-Deciduous Forest
Mixed conifer-deciduous forests covered approxi-
mately 2 percent of the total area of the Watana
and Gold Creek watersheds. This vegetation type
had mean overstory cover values intermediate
between mean cover values for spruce stands and
those for deciduous stands. This forest type was
typically dominated by white spruce and paper
birch. Elevations for mixed conifer-deciduous
forest average 1530 feet (466 m) (range 1200 to
2250 feet; 370 to 690 m), with closed stands having
a mean elevation near 1394 feet (425 m) (range 1300
to 1450 feet; 400 to 440 m), and open stands
occurring around 1581 feet (482 m) (range 1200 to
2250 feet; 370 to 690 m). • Most of the 1 arger
stands were found on slopes downstream from Tsusena
Creek (Figure E .3.36}. These were successi anal
stands which developed as spruce replaced deciduous
trees.
E-3-207
3 -BOTANICAL RESOURCES
Mixed conifer-deciduous forest had a well-developed
ground layer with predominant species including
bluejoint, bunchberry, woodland horsetail, and
knight's plume-moss (Ptilium sp.) (Tables E.3.60
and E.3.61). Overstory cover in closed mixed
stands is about 60 percent and that in open mixed
stands is approximately 38 percent. Overstory
height was sometimes up to 66 feet (20m). The dbh
of individual trees ·in these two-species
overstories ranged from 0.5 to 1.0 feet (15 to
30 em).
Cores from larger trees indicated that mature birch
in mixed stands averaged about 90 years old or
older. Rotten centers precluded accurate aging in
older birch trees. White spruce ages ranged from
50 to 204 years, with most trees older than 100
years.
Plant species composition and abundance differed
between open and closed stands of mixed conifer-
deciduous forest. The shrub 1 ayer contributed
greater cover (17 percent) in open stands than in
closed stands (4 percent) because tall blueberry
willow was more abundant there than in closed
stands (Tables E.3.60 and E.3.61).
(ii) Tundra
Tundra communities covered 24 percent (975,267 acres,
394,685 ha) of the Watana and Gold Creek watersheds
and usually occurred above the 1 imit of tree growth
(Figure E.3.38). Most of the well-vegetated commun-
ities occurred in flat to gently sloping areas.
Sparser vegetation was present on steep or rocky
terrain. Although tundra species composition was
highly variable, four distinct subtypes were identi-
fied in areas 1 arge enough to map--wet sedge-grass
tundra, mesic sedge-grass tundra, herbaceous alpine
tundra, and closed mat and cushion tundra.
Wet sedge-grass tundra cormu niti es covered a small
amount of the total area (0.3 percent) and occurred
at a mean elevation of 1926 feet (587 m) (range 1400
to 2550 feet, 430-780m) in wet, depressed areas with
poor drainage. They had almost 100 percent vegeta-
tion cover, with most species occurring in the ground
layer (Table E.3.62). Predominant herbaceous species
were water sedge, Bigelow sedge, sphagnum moss, and
bluejoint. The shrub layer, when present, contained
scattered individual willows. There was
E-3-208
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3 -BOTANICAL RESOURCES
usually a large amount of organic matter in soils of
wet sedge-grass communities, and in some cases a
thick organic layer overlaying mineral soil. Wet
sedge-grass tundra is noted as a wetland type in
Section 3.2.3.
Mesic sedge-grass tundra was the largest tundra sub-
type (11 percent cover) and occurred at a mean eleva-
tion of 4502 feet (1372 m) on well-dra.ined, rolling
uplands. The underlying soil was well-developed in
some areas, but in others the soi 1 was patchy and
interspersed with rocks. Mean Vegetation cover was
65 percent for the two 1 ocat ions surveyed {Table
E.3.63). All vegetation was in the ground layer, and
species were usually 1 ess than 1 foot (30 em) tall.
Bigelow sedge was the most common species and
accounted for almost half of the total vegetation
cover.
Two types of herbaceous alpine tundra were found in
the Watana and Gold Creek watersheds, although only
one type, herb-sedge tundra, was predominant in areas
1 arge enough to map. Herb-sedge communities covered
less than 1 percent of the total area and occurred at
elevations of about 4249 feet {1295 m) (range
unavailable), near the glaciers of the upper basin
{particularly the West Fork Glacier) on gentle,
well-drained slopes with relatively well-developed
soils. Vegetation cover in herb-sedge tundra was
nearly 100 percent. A 1 ist of the 42 species found
in one stand of herb-sedge turidra is shown in Table
E. 2. 64. Cover of each species caul d not be
determined because of the complex vegetation pattern.
The other type of herbaceous alpine community was
present in small, isolated rocky areas. Small forbs
and sometimes shrubs grew in pockets of mineral soil
imbedded between the rocks.
The fourth major type of tundra community found with-
; n the Watana and Gal d Creek watersheds was mat and
cushion tundra (total 4 percent cover), found at high
elevations (3280 feet; 1000 m) (range 2600 to 4000
feet; 302 to 1219 m) on dry, windy ridges.
Vegetation cover was about 75 percent and was usually
less than 8 to 12 inches {20 to 30 em) tall (Table
E. 3. W16). Lichens and 1 ow mat-forming shrubs were
major constituents. Soils were shallow and coarse.
Uplands within the Gold Creek watershed supported
extensive areas of a mixed vegetation type consisting
E-3-209
3 -BOTANICAL RESOURCES
of interspersed mat and cushion and sedge-grass
tundras ( 9 percent tot a 1 area) (Figure E. 3. 38).
(iii) Shrubland
Shrub 1 and vegetation types were the most prevalent
of all vegetation types and comprised almost 40
percent cover in the Watana and Gal d Creek water-
sheds. Including approximately 65 plant species,
shrublands generally occupied areas at higher
elevations than forest communities, but at lower
elevations than tundra types. Two main types were
found: tall and low shrub. Most shrublands,
particularly the low shrub, were found on extensive,
fairly level benches at mid-elevations throughout the
Watana and Gal d Creek watersheds. Less extensive
areas, usually tall shrubs, were found on steep
slopes above the river. Tall and low shrub types
were further divided by percent shrub cover into
closed and open types.
-Tall Shrub Types
Tall shrub communities covered approximately 8
percent of the total area and were dominated by
Sitka alder and were found mostly on steep slopes
above the Susitna River or sometimes above flat
benches at a mean elevation of 1880 feet (573 m)
(range 1600 to 2550 feet; 490 to 780 m) (Figure
E.3.38). Many of these stands were 7 to 13 feet (2
to 4 m) tall. Approximately 25 species were
identified in the alder stands (Table ~.3.66).
Alder stands frequently occurred as narrow strips
through other vegetation types on the slopes
adjacent to the Susitna River. Alder would also be
present in rings at a particular elevation around
mountains or in strips along tributary streams,
such as Portage Creek. Closed stands had a 1 most
complete vegetation cover, contributed primarily
by the ground layer and understory (Table E.3.66).
One open alder stand surveyed had less vegetation
cover than the closed stands (85 percent and 96
percent cover, respectively), with greatest percent
cover in the understory layer (Table E.3.67).
Bluejoint was the predominant ground layer species
in open and closed stands.
E-3-21 0
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3 -BOTANICAL RESOURCES
( i v)
( v)
-Low Shrub Types
Low shrub vegetation types were found to be common
in the Watana and Gold Creek watersheds where they
covered 32 percent of the total area. Low shrub
communities were widespread on the extensive, rela-
tively flat river benches (mean elevation: 2562
feet, 781 m) (range 2100 to 3200 feet, 640 to 980
m), where soils were frequently wet and gleyed, but
usually without standing water. Birch and wi 11 ow,
generally 3.3 to 4.9 feet (1.0 to 1.5 m) tall, were
predominant in both separate and mixed stands. The
cover percentages of ten closed and two open 1 ow
shrub stands sampled are shown in Tables E. 3. 68
and E.3.69, respectively.
Birch shrub stands were usually dominated by resin
birch 3.3 feet (1 m) tall, and contained several
other low shrub species, especially northern Labra-
dor tea. Predominant ground layer species were bog
blueberry, mosses and lichens. Willow shrub stands
were usually in wetter areas than birch shrub
stands. Diamondleaf willow was commonly predomin-
ant, forming thickets along small streams at high
elevations. Because of the wetness, these communi-
ties were usually less botanically diverse than
birch shrub stands. Water sedge, northern Labrador
tea, and bog blueberry were the predominant ground
1 ayer species.
Herbaceous Communities
Two herbaceous community types were found in the
Watana and Gal d Creek watersheds. Grasslands domi n-
ated by bl uejoi nt were present on 1 evel to sloping
areas at lower elevations a·long the Susitna River and
Portage Creek (less than 1 percent total area) (Table
E.3.52 and Figure E.3.53 through E.3.65). Herbaceous
communities were too small to map at a scale of
1:250,000 and do not appear in Table E.3.51.
Herbaceous pioneer communities (too small to map)
·were present on recently vegetated gravel and sand
bars where soils had little organic matter and often
consisted primarily of cobble. Pioneer species
included horsetails, lupines, and alpine sweetvetch.
Aquatic Vegetation
Lakes and ponds surveyed for aquatic vegetation are
shown in Figure E.3.75. Aquatic species identified
during these surveys are 1 i sted by site in Table
E-3-211
3 -BOTANICAL RESOURCES
E. 3. 70. A summary of the dominant aquatic species
and factors which may influence their locations in
and around many of the water bodies in the Watana and
Gold Creek watersheds is presented in Figure E.3.76.
Bur reed and ye 11 ow pond 1 i ly probably contributed
more to total cover than all other aquatic species
combined. Yellow pond lily, a submerged species with
large floating leaves, was particularly prominent and
formed 1 arge beds in several water bodies. It was
absent along the edges of ponds and appeared to grow
best at depths ranging from 2. 0 to 7. 0 feet (0. 6 to
2.1 m), frequently formfng a band around ponds and
lakes between the shallows and deep water. Bur reed,
in contrast, frequently dominated the shallows of the
ponds from 0.5 to 2.0 feet (0.15 to 0.60 m) in depth.
Horsetail, mare 1 s tail, and bladderwort were also
common in these shal.lows. Horsetail was common on
rocky bottoms where little other vegetation was
present. Bladderwort was prominent in shallows
having a mud bottom or a bottom of organic matter.
Along the edges of water bodies, sedges appeared to
contribute more to total cover than all other edge
species combinedo They were the prevalent species of
the pond shallows, along the pond periphery, and also
on floating mats when they are present.
Lakes and ponds with gently sloping substrates had
more aquatic plants, both submerged and emergent,
than did water bodies with steeply sloping sub-
strates; but above 3100 feet (945 m) in elevation,
there was usually sparse aquatic vegetation cover
regardless of substrate morphology. Rocky bottoms
supported less aquatic vegetation than did mud or
sand bottoms. Floating mats of vegetation were
sometimes a part of the associated emergent wetland.
These mats were dominated by sedges, sphagnum moss,
and other common bank species.
Watana Lake was unique in that it was dominated by
Robbins pondweed, a submerged rooted aquatic species
that grows in water from about 4.0 to 8.0 feet (1.2
to 2.4 m) in depth. The reason for the lack of other
vascular plants in Watana Lake and the presence of
Robbins pondweed is not understood. (See Section
3.1.2(b) for further discussion of this species.)
(vi) Unvegetated Areas
Unvegetated areas were found to cover 15 percent of
the total area (601,422 acres, 243,392 ha) of the
E-3-212
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3 -BOTANICAL RESOURCES
(vii)
Watana and Gold Creek watersheds and 6 percent of the
total area {66,665 acres, 26,979 ha) 16 km on either
side of the Susitna River from Gold Creek to the
Maclaren River. Three classes of unvegetated area -~
water, rock, and snow and ice --were identified and
mapped {Figures E.3.38, E.3.39 through E.3.41, and
E.3.53 through E. 3.65). Lakes and streams were
included ·in the water category. Lakes were generally
found along flat benches and ranged in size from
sma 11 ponds to 1 arge 1 akes such as Big Lake
(approximately 112 acres; 450 ha). Rock was bedrock
or deposited geologic materials supporting little or
no vascular vegetation. Rock occurred as
outcroppings at high elevations, as steep cliffs
along the Susitna River and tributaries, or as
unconsolidated gravel in newly deposited river bars.
These river.bars were usually first colonized by
horsetails, mountain-avens, and willows. Snow and
ice included permanent snowfields and glaciers; these
were most common at the northern end of the study
area in the Alaska Range, but some occurred near the
southern boundary in the Talkeetna Mountains.
Comparison of the Watana and Gold Creek Watersheds
Tables E.3.71 and E.3.72 provide an approximate
comparison of vegetation communities and their
relative areal extents for the Watana and Gold Creek
watersheds, respectively (Figure E.3.36). A
comparison of percent total area covered by each
vegetation type in the two areas (Tables E.3.71
and E. 3. 72) shows sever a 1 notable differences which
are apparent also from inspection of vegetation
patterns mapped at the 1:250,000 scale (Figure
E.3.38). Differences in the abundance of vegetation
types from one area to another are reflected in the
impact analyses for bot ani cal resources and wildlife
{Exhibit E, Chapter 3, Sections 3.3 and 4.3,
respectively).
Although the Watana and Gold Creek watersheds had
nearly equal percent cover by forest, conifer forest
was much more abundant in the Watana watershed (21.
percent Watana, 4 percent Gold Creek). In the Gold
Creek watershed, conifer forest types were confined
mainly to north-facing slopes and adjacent benches in
the Fog Lakes and Stephan Lake vicinities; whereas
conifer forest occurred extensively throughout
eastern, central, and northwestern areas of the
Watana watershed.
E-3-213
3 -BOTANICAL RESOURCES
By contrast, mixed forest types were far more abun-
dant in the Gold Creek watershed (0.5 percent Watana,
18 percent Gold Creek), particularly along the main-
stem Susitna River; Devi 1, Cheechako, and Portage
Creeks; and the Indian River. Percent cover by
deciduous forest was very sma 11 for both the Watana
and Gold Creek watersheds. Balsam poplar stands (too
sma 11 to map) were present in the Sus itna River
floodplain and along tributary streams. The percent
of total area covered by tundra vegetation types
within the Gold Creek watershed was nearly twice that
of the Watana watershed (22 percent Watana, 41
percent Gold Creek). This difference was mainly due
to the predominance of mixed mat and
cushion/sedge-grass tundra on the uplands to the
north and south of the Devil Canyon impoundment area,
and to the relative scarcity of this type in the
Watana watershed (6 percent Watana, 33 percent Gold
Creek).
Mesic sedge-grass tundra was more abundant in the
Watana watershed, where it occupied high-elevation,
we 11-drai ned uplands in the northeast reaches of the
Talkeetna Mountains south of the Susitna River (13
percent Watana, 0.3 percent Gold Creek).
The distribution of shrubland vegetation varied
greatly between the Watana and Gold Creek watersheds
(40 percent Watana, 28 percent Gold Creek). Tall
shrub vegetation (alder stands) was abundant on steep
slopes along the drainages of the Gold Creek water-
shed, occupying extensive areas north of the Susitna
River. Large stands of tall shrub vegetation were
much less abundant in the Watana watershed (7 percent
Watana, 18 percent Gold Creek).
Low shrub vegetation, predominantly mixed birch-
wi 11 ow shrub, was extremely abundant throughout the
southern, central, and eastern portions of the Watana
watershed and covered a greater percent of the total
area (34 percent) than any other vegetation type.
Low shrub stands in the Gal d Creek watershed were·
much more 1 ocal , as on the slopes between Tsusena
Creek and Swimming Bear Lake, and covered only 11
percent of the total area.
(c) Devil Canyon to Talkeetna
The Susitna River from Devi 1 Canyon (RM 155) to Talkeetna
(RM 103) flows through a steep canyon that opens out near
Talkeetna. Vegetation is established slowly in the flood-
E-3-214
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3 -BOTANICAL RESOURCES
plain until sufficient silts and sands are deposited by wind
and water to provide a parent material for so11 development.
Scouring by ice and water during spring breakup and fall
freeze up, and by high water during summer floods accounts
for much of the vegetation dynamics in the floodplain.
Willow and balsam poplar are common early successional
(pioneer) species on the Susi tna River fl oodpl ai n. They
become established on the most recently deposited river
bars. As the pioneer communities mature, balsam poplar
becomes dominant. The oldest, most stable areas are usually
covered with mixed conifer-deciduous (birch-spruce) forest.
(i) Early Successional Stands
Early successional communities accounted for 5 to 10
percent of vegetated land on the floodplain. They
were usually dominated by horsetai 1 and/or Drummond
mountain-avens in the ground layer and balsam poplar
and/or willow in the shrub layer. Characteristi-
cally, these communities had little total vegetation
cover and greater than 50 percent bare ground {Table
E.3.73). Plant species in these types generally had
rhizomes, or horizontal underground stems, which
could extend for many meters and were effective in
binding loose sand and silt. Avens was important in
stabilizing gravelly sites. Early successional
stands may be carrel ated with 1 ow wi 11 ow or mixed
shrub and tall shrub vegetation types.
In most stands, ba 1 sam pop 1 ar and wi 11 ow occur red at
greater densities than other woody species, but alder
had a relatively rapid growth rate and began to over-
top willow and balsam poplar within two or three
years after its establishment.
Floodplain balsam poplar and willow stands may last
up to ten years from the time of the last major dis-
turbance. Aging of these stands is difficult because
floods frequently bury several years • plant growth in
silt, and new growth is present above the silt. This
cycle may be repeated a number of times before vege-
tation succession advances to a later stage.
(ii) Mid-Successional Stands
Deposition of sands and silts that raise the eleva-
tion of sites above the level of frequent flooding is
necessary for transition of early successional vege-
tation to mid-successional stages. Mid-successional
E-3-215
3 -BOTANICAL RESOURCES
types accounted for about one-fifth of vegetated land
surveyed in the Susitna floodplain. Thinleaf alder,
or balsam poplar that had developed into tall shrubs
or immature trees, dominated these stands. Mid-
successional stands include the open ann closed tall
shrub and balsam poplar forests of Viereck and
Dyrness (1980). The alder type was the first phase
and appeared to persist from 10 to 25 years after
stabilization. Balsam poplar appeared to dominate 25
to 55 years after stabilization, but stands of this
type were much 1 ess common than the younger
alder-dominated stands. As noted earlier, alder
overtops balsam poplar during the transition from
early-to mid-successional stages. However, after
about 20 years, the balsam poplar that remains
rapidly increases in height, thereby overshadowing
the alder and developing into the immature balsam
poplar phase of the mid-successional stage.
In both alder and balsam poplar stands, there was
essentially no bare ground. As balsam poplar assumes
greater dominance, its density and that of thinleaf
alder and feltleaf willow decline from that found in
the earlier alder stands, since the balsam poplar
trees become larger; but Sitka alder, prickly rose,
and highbush cranberry increase in density {Table
E.3.74 and E.3.75).
(iii) Late Successional Stands
As the balsam poplar stands of mid-succession mature,
white spruce may appear in the canopy. Mature balsam
poplar stands probably are established by about 75
years after stabilization and live for about 30 more
years. Eventually, the large balsam poplars die,
1 eavi ng space for development of more balsam poplar
or spruce and birch, if no disturbances interrupt the
process. The corresponding vegetation types of the
late successional stands are balsam poplar forest and
mixed conifer-deciduous forest. Factors which cause
development of the birch-spruce stands or alterna-
tively promote continuation of the balsam poplar are
not understood.
Mature and decadent (gradually dying) balsam poplar
stands were found on 25 to 40 percent of the vege-
tated floodplain; mixed stands of birch and spruce
occupied 23 to 32 percent of the area. Mature and
decadent balsam poplar stands collectively averaged
90 percent total vegetation cover. Birch-spruce
E-3-216
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communities contained 12 percent cover of white
spruce in the overstory (Table E.3.76}.
Birch-spruce forest types had the greatest variation
in stand structure of the vegetation types found on
the fl oodpl ai n. There is some evidence that these
stands are self-perpetuating. Upon overmaturity, the
birch overstory tends to fall, making the spruce more
susceptible to wind-throw and thereby allowing a
shrubby paper birch-a 1 der-hi ghbush cranberry-prickly
rose community to develop. The shrub community then
progress.es to the birch-spruce forest stage.
(d) Talkeetna to Cook Inlet
Vegetation in the fl oodpl ai n downstream from Ta·l keetna had a
simi 1 ar successional sequence to that upstream from
Talkeetna. It consisted primarily of bottomland spruce-
hardwood fore.s.ts (Commonwealth Assoc. 1982). The islands
and river bars were somewhat more stable than those upstream
from Talkeetna because of the width of the floodplain, which
reduces ice jam damage and the severity of flooding. This
increase in stabi 1 i ty correspondingly increases the average
age and successional stage of the vegetation present in the
fl oodpl ai n.
Separate mapping of this area was not undertaken.
(e) Transmission Corridors
( i ) Healy to Fairbanks
The classification system used to map the Healy-to-
Fairbanks transmission corridor (Figures E.3.48
through E. 3. 50) was the same as that used for the
Watana and Gold Creek watersheds (see Viereck and
Dyrness 1980). The corridor crosses three di st i net
physi ographi cally and phytosoci ol ogi cally di sti net
sections: Healy to Nenana River, Tanana Flats
(Nenana River to Tanana River), and Tanana River to
Fairbanks. Forest types accounted for almost 78
percent of the 274,000 acres (111,000 ha) of the
corridor, with open forest types being dominant
(Table E.3.77). Open spruce covered 28 percent of
the area, open deciduous 11 percent, and open mixed
conifer-deciduous 11 percent.
The Healy-to-Nenana River section includes a dis-
sected plateau on the west side, a relatively flat
area in the middle, and the Parks Highway and Nenana
E-3-217
3 -BOTANICAL RESOURCES
River to the east. Vegetation along the ridges lead-
; ng from the plateau is predominantly open coni fer
(spruce), open mixed conifer-deciduous, and open
deciduous forest. The flat area is predominantly low
shrub with sedge-grass and open and closed coni fer
types. Most of the spruce trees are relatively
short, except along the streams.
The Tanana Flats area extends from just beyond the
Nenana River crossing to the Tanana River. This
section has a mosaic of wet vegetation types (dis-
cussed further in Section 3.2.3) which include open
spruce stands with 1 arch' 1 ow shrub' and wet sedge-
grass. The distribution of many vegetation types
appears to be a consequence of old stream meanders
and drainage patterns. Some patches of deciduous
forest occur. Dry streambeds have stringers of other
vegetation, such as low shrub, along them.
The section from the Tanana River to Fairbanks passes
through rolling hills covered predominantly with open
deciduous forest. Sma 11 areas of spruce are 1 ess
common than in the Tanana Flats section. The mixed
woodland patches in this section are generally cut-
over areas. Many of the closed spruce areas produce
very short shrub-like trees.
Most coniferous forest between the Tanana River and
Fairbanks contain only spruce; few have larch. About
half the areas in the Tanana Flats section contain
larch as well. Spruce (presumably black spruce)
occurs in 1 ow, poorly drained areas. Spruce in
better-drained locations may be either black or white
spruce. The black spruce-larch type, confined in
Alaska to the interior, is generally found only on
wet lowland sites with shallow permafrost (Viereck
and Dyrness 1980).
(ii) Willow to Cook Inlet
The Willow-Cook Inlet transmission corridor passes
through three pri nci pa 1 kinds of plant communities--
(1) closed birch and mixed conifer-deciduous forests,
(2) wet sedge-grass marshes, and (3) open and closed
spruce stands (Table E.3. 78 and Figures E.3.51 and
E.3.52).
The Willow-Cook Inlet corridor includes approximately
95,000 acres (39,000 ha) (Table E.3. 78). It passes
through relatively flat terrain that is 67 percent
E-3-218
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3 -BOTANICAL RESOURCES
forested, predominantly with coni fer-deciduous
forests. Approximately 24 percent of the area is wet
sedge-grass marsh, discussed further in Section
3.2.3.
Closed conifer-deciduous forest is the predominant
vegetation type, covering 29 percent of the total
area. These forests contain birch, white spruce, and
ba 1 sam pop 1 a r trees. B·i rch is the predominant
deciduous species. Many sites have developed either
a woodland/ shrub 1 and or woodland/ grassland aspect.
In the vicinity of Willow, localized stands of balsam
poplar are associ a ted with the active river
fl oodpl ai n.
Wet sedge-grass marsh is the second most common vege-
tation type in this area (24 percent cover). This
type has an extensive distribution and is associated
with diverse networks of ponds, 1 akes, and meandering
streams. These areas support little other vegetation
except for scattered islands of black spruce and low
shrubs on drier sites. They are discussed further in
Section 3.2.3.
White spruce, common in most of interior Alaska, is
less common in this part of the Susitna Valley. How-
ever, most closed and open spruce stands (8 and 9
percent cover, respectively) in areas dominated by
mixed conifer-deciduous forest are probably white
spruce. Spruce stands skirting wet sedge-grass or
low shrub areas may be white or black spruce or mix-
tures of the two. Most woodland spruce stands are
black spruce.
(iii) Willow to Healy
The Willow-to-Healy intertie corridor is covered by
interior forests, muskeg, shrub communities, and
tundra. White spruce and paper birch dominate the
drier forested landscapes; black spruce is primarily
located on poorly drained sites. Additionally, bal-
sam poplar and white spruce develop on the flood-
pl ai ns. Within or adjacent to these areas, about
thirty species of willow and several species of alder
occur in the understory or in thickets with little or
no overs tory.
The southern two-thirds of this corridor contain
forested areas; the northern portion consists mainly
of open woodland, shrubland, and tundra. The
E-3-219
3 -BOTANICAL RESOURCES
corridor contains fewer glaciers and ice fields than
is common in similar sized areas in the region
(Commonwealth Assoc. 1982). Upland and 1 owl and
spruce-hardwood forest together cover nearly three
quarters (71 percent) of the total area within the
Wi 11 ow-to-Healy transmission corri dar. Upland
spruce-hardwood forest stands cover 2888 acres (1169
ha) and 1 owl and spruce-hardwood forest stands cover
1503 acres (608 ha). Shrublands are the third most
predominant cover type (nearly 12 percent) and occupy
713 acres (290 ha). Vegetation types within the
intertie corridor, their areal extent, and percent
toal area covered are presented in Table E.3.79
(modified from Commonwealth Assoc. 1982).
(iv) Dams to Intertie
Vegetation types crossed by the proposed centerline
of the transmission corridor from the Watana and
Devil Canyon damsites to the intertie junction are
shown at a scale of 1:63,360 in Figures E.3.39 and
E.3.40. Nearly one-half (49 percent) of the total
area (938 acres, 380 ha) within the Watana-to-Devil
Canyon section of the transmission corridor is
shrubland. Predominant vegetation types crossed
include closed tall shrubland (128 acres; 52 ha), low
willow shrubland (218 acres, 88 ha), sedge-grass
tundra (117 acres; 47 ha), sedge-shrub tundra (119
. acres, 48 ha), and mat and cushion tundra {126 acres.
51 ha). The Devil Canyon-to-intertie section of the
transmission corridor covers a total of 325 acres
(132 ha), 277 acres (112 ha) of which is closed mixed
forest. A small amount of wet sedge-grass tundra (28
acres, 11 ha) also exists within the corridor. The
areal extent and percent total area for· coverage by
each vegetation type within the Watana-to-Devil
Canyon and Devil Canyon-to-intertie sections of the
transmission corridor are presented in Table E.3.80.
3.2.3 -Wetlands
Wetlands are lands where saturation with water is the dominant
factor determining the nature of soil development and the types
of plant and animal communities living in the soil and on its
surface. These areas are characterized by soil or substrate that
is at least periodically saturated with or covered by water
E-3-220
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3 -BOTANICAL RESOURCES
{Cowardi n et al. 1979). Because wetlands are recognized to have
important resource values, they are protected by state and
federal regulations (Alaska Office of Coastal Management 1982).
Examination of potential project impacts to wetlands, and how
such impacts can be avoided, is mandated by Executive Orders
11988, 11990, and 11991, and by Section 404 of the Clean Water
Act as amended (86 Stat. 884, USC 1344).
The classification system of Cowardin et al. (1979} recently
adopted by the USFWS (1980b) defines wetlands as having one or
more of the following characteristics: (1) at least periodical-
ly, the land supports predominately hydrophytes; (2) the sub-
strate is predominately undrained hydric soil; or (3) the sub-
strate is nonsoi 1 and is saturated with water or covered by
shall ow water' at some time during the growing season of each
year.
Section 404 of the Clean Water Act extends permit authority to
the U.S. Army Corps of Engineers (COE) for all waters of the
United States, including wetlands. The COE•s reguations (33 CRF
320-330) define "wetlands" to mean "those areas that are inun-
dated or saturated by surface or ground water at a frequency and
duration to support, and that under normal circumstances do sup-
port, a prevalence of vegetation typically adapted for life in
saturated soi 1 conditions. Wetlands generally include swamps,
marshes, bogs and similar areas."
In Exhibit E, Chapter 3, the term "wetland" is used in three
different ways. In discussions of impacts and mitigation invol-
ving wetlands in general, the term is used to denote areas at
1 east partly characterized by hydrophilic vegetation and the pre-
sence of standing water or sheet flows. In addition, wetlands
mapping of the impoundment zones, adjoining borrow and
construction areas, and access corridors by McKendrick et al.
(1982) uses wetland types defined by Cowardin et al. (1979) based
on corre 1 at ion with Viereck and 1Dyrness ( 1980) vegetation types
mapped to classification Level III (Section 3.2.2(a)). Finally,
two vegetation types characteristic of wet or poorly drained
areas, wet sedge-grass and black spruce forest, were mapped for
the Healy-to-Fairbanks and Willow-to-Anchorage transmission
corridors by TES and Acres Arne ri can Incorporated ( 1982, modified
from McKendrick et al. 1982). Only wetland types mapped as
defined by Cowardin et al. {1979} are descr·ibed in quantitative
terms or shown as fiures herein.
(a) Methods
Wetland vegetation types were mapped by McKendrick et al.
{1982) at a scale of 1:24,000 from the Oshetna River to the
Devil Canyon damsite, using the system of Cowardin et al.
{1979) (Figures E.3.66 through E.3.73). This mapping
E-3-221
3 -BOTANICAL RESOURCES
covered the impoundment areas and adjoining construction and
borrow areas. The access corridors were mapped at a scale
of 1:63,360 {Figures E.3.47 through E.3.47).
Wetland maps were produced by first correlating the vegeta-
tion types from Viereck and Dyrness (1980) with cover
designations from the wetlands classification of Cowardin et
al. (1979) (Table E.3.81). Corresponding wetlands
categories were then superimposed over the vegetation maps
of the 1:24,000 scale prepared by McKendrick et al. {1982).
The presence of steep slope and 1 i kely good drainage was
interpreted to rule out classification as wetland. Lakes,
ponds, rivers, and streams were not specifically
classified.
Because the system of Cowardin et al. (1979) requires addi-
tional data on hydric soils and periodic ambient water
conditions to characterize wetlands completely, the mapping
is liberal and indicates areas which potentially qualify as
wetlands und.er that system. Portions of these areas may
be eliminated by further considerations of soil and water
conditions. Data on soils and water will be collected in
the future during detailed construction planning and used to
refine the identification of wetland areas in accordance
with the requirements of Section 404 of the Clean Water
Act.
Aquatic vegetation of the Watana and Gold Creek watersheds
was examined during August 1982. In order to obtain site-
specific information on aquatic plant species, 24 selected
ponds and 1 akes and their adjacent uplands were surveyed on
foot, from Devi 1 Canyon (RM 152) to the confluence of the
Susitna and Oshetna Rivers {RM 233) (Figure E.3.75).
During the surveys, species composition, dominance, and
total cover (relative to the amount of water) were esti-
mated. Elevation, estimated rooting depth, and width of
surrounding wetland area were recorded. Surrounding wetland
was limited by definition to the Lacustrine-Limnetic-
Emergent Wetland-Vascular wetland class of Cowa rdi n et al.
(1979). Many remaining ponds and lakes were examined by
helicopter overflights.
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3 -BOTANICAL RESOURCES
{b) General Description
Wetlands within the Susitna project area include riparian
zones, ponds and lakes on upland plateaus. and wet tundra.
These we~l ands support waterfowl in the summer {23. 8
adults/km censused in July 1981), and are also used by
migratory birds in spring and fall. Although the density
and diversity of bird species are lower for the Susitna
project area than for many other areas of Alaska (Kessel et
al. 1982a}, seaters, terns, scaup, mallards, American
wi dgenns, swans, and other waterfowl were found during
wetland surveys (Section 4.2.3[6]).
Wetland areas in the vicinity of the project include upper
Brushkana Creek and Tsusena Creek, the area between 1 ower
Deadman Creek and Tsusena Creek, the Fog Lakes area, the
Stephan Lake area, Swimming Bear Lake, and Jack Long Creek
(Figure E.3.36). There are large number of lakes in the
extensive flats of the Watana watershed, such as those in
the Lake Louise area. Vegetation types indicating potential
wetlands within the Watana and Devil Canyon impoundment
areas and within borrow sites proposed for dam construction
are shown in Figures E. 3. 66 through E. 3. 73.
As illustrated in Table E.3.81, the wetlands classification
of Cowardin et al. (1979) may be used as a second level of
classification applied to the vegetation types previously
discussed (Section 3.2.2). Areal extent of vegetation types
in the Watana and Gold Creek watersheds are listed in Tables
'E. 3. 51 and E. 3. 52. The most common vegetation type
occurring in this area was the low shrub type {32 percent
total cover). This vegetation type corresponds to the
potential palustrine scrub-shrub wetland type of the
Cowardi n system (1979). The areal extent 1 i sted indicates
the potential areal extent of palustrine scrub-shrub wetland
type. Woodland spruce forests cover nearly 12 percent of
the Watana and Gold Creek watersheds and include a portion
of the potential palustrine forested areas. Wet sedge-grass
tundra covers less than 1 percent of the total area. Lakes
and rivers comprised a total of 21.4 percent of the entire
Watana and Gold Creek watersheds •
The areal extents of different potentia 1 wetland vegetation
types which wi 11 be affected by the Watana and Devi 1 Canyon
developments are indicated in Table E.3.82. The estimates
of total palustrine wetland areas shown in this table are
extremely liberal, because tl)e wetlands were highly
integrated with non-wetlands, and supporting soil and water
data were not used to refine the areas mapped. As described
E-3-223
3 -BOTANICAL RESOURCES
below additional wetland mapping is in progress. Therefore,
the values shown in Table E.3.82 should be considered
preliminary.
Wet sedge-gress and potential wet spruce areas occur within
the Healy-to-Fairbanks and Wi 11 ow-to-Anchorage transmission
corridor study areas. As discussed further in Section
3.4.2{c) the centerl ines will be further evaluated in the
field and adjusted to avoid wetland areas as determined by
the analysis of vegetation, soils, and water data.
Aquatic species identified in the Watana and Gold Creek
watersheds, percent cover of aquatic vegetation, and
surrounding wetland width are listed by site in Table
E.3.70. Wetland sites sampled ranged in elevation from 1700
feet to 3000 feet {518 m to 914 m). A summary of the domi-
nant aquatic species and factors which may influence their
location in and around many of the waterbodies in the Watana
and Gold Creek watersheds is presented in Figure E.3.76 (see
Section 3.2.2[b][v] Aquatic Vegetation for further discus-
sion).
Additional mapping of wetlands is being conducted (Section
3.2.2[a]); preliminary maps and estimates of wetland areal
coverage will be available in June 1983. Maps are being
prepared at a scale of 1:24,000, using low-altitude color
infrared and true-color photography taken in 1980-1982. The
herbaceous vegetation type of Viereck et al. (1982) is being
mapped to Level IV, and forest and shrub types are being
mapped to at least Level IV with wetland modifiers (modi-
fiers indicate which areas are subject to flooding). The
area being mapped includes the impoundment and dam areas,
borrow sites, construction camps and village, and access
corridors.
3. 3 -Impacts
Impacts of the Susitna Hydroelectric Project on vegetation are of two
general kinds --(1) loss of all vegetative cover; and (2) change in
the nature of vegetatative cover (i.e., alterations in plant community
types). The first kind of impact is considered adverse; while the
second kind may be considered adverse or beneficial depending upon its
effect on wildlife. The following discussions treat both kinds of
impact.
E-3-224
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3.3.1 -Watana Development
The Watana development includes areas affected by the Watana
impoundment zone, borrow sites, dam and spill way, construction
camp and airport, and permanent village. Impacts of access roads
and transmissions corridors are discussed separately.
(a) Construction
(i) Vegetation Removal
Construction of the Watana development will result in
the direct removal of vegetation within an area of
approximately 40,974 acres (16,582 ha) covering a
range of elevations from approximately 1400 to 2400
feet (430 to 7~9 m). Within the dam, spillway, and
impoundment areas, about 36,642 acres (14,329 ha) of
vegetation will be removed by construction and clear-
ing operation. Included are 26,730 acres (10,818 ha)
of forest that is composed primarily of large stands
of both woodland and open black and white spruce, as
well as some open mixed forest types. The camp,
village, airstrip, and borrow areas will remove an
additional 4300 acres (1742 ha), most of which is
shrubl and or black spruce forest. Spoil areas will
alter vegetation between 1400 and 1600 feet (430 and
488 m). All vegetation removed during construction
of the Watana dam, reservoir, and ancillary support
facilities will represent about 1 percent of the
total vegetation of the Watana and Gold Creek water-
sheds (defined in Section 3.2.2; see Figure E.3.36).
Table E.3.83 1 ists the area of each vegetation type
to be directly removed by the Watana development, and
compares each value to the total area of that vegeta-
tion type within the Watana and Gold Creek water-
sheds. Approximately one-third (34 percent) of the
open birch stands, and all 1 arge closed birch stands
in the Watana and Gold Creek watersheds will be
removed by the Watana development. The relative loss
of other types is small when compared to their avail-
ability in the basin. For example, only 3.4 percent
of forested areas, 0.1 percent of tundra types, and
0.4 percent of shrubland cover types will be directly
removed by the development.
E-3-225
3 -BOTANICAL RESOURCES
(ii) Vegetation Loss by Erosion
Erosion is a persistent problem at dam construction
sites in northern latitudes (Baxter 1977, Baxter and
Glaude 1980). Erosion following the clearing of
vegetation may be promoted by the following:
-Destabilization of till;
-Blowdown of trees near cleared areas;
-Thawing of permafrost;
-Desiccation of exposed soils; and
-Changes in drainage patterns.
Slope stability studies by Acres American {1982)
indicate that areas particularly vulnerable to vege-
tation loss through erosional effects include side
slopes of the canyon from the south abutment of the
Watana damsite (RM 184) to Vee Canyon (RM 225), along
Watana Creek ( RM 194) , and from the Watana reservoir
headwaters to the Oshetna-Goose Creek area (RM 243 -
233). Approximately 1379 acres (558 ha) above the
impoundment shoreline were shown as potentially
unstable and thus subject to vegetation loss.
(iii) Vegetation Damage by Wind and Dust
Blowdown of trees is a recognized problem in cleared
areas (Todd 1982). Near reservoirs, it is promoted
by increased winds due to a greater fetch as areas
are cleared (Baxter and Glaude 1980, Brown 1972).
Since northeasterly winds predominate in the project
area most of the year, the greatest bl owdown poten-
tial is in the woodland black spruce stands on the
south side of the Watana damsite. The shallow
rooting depth typical of black spruce 12 inches
{35 em) indicates that this vegetation type is
subject to blowdown (McKendricle 1982 pers. comm).
Wind-generated dust is expected to occur during con-
struction activities, particularly during and follow-
ing clearing of the impoundment and borrow areas.
Increased wind fetch is expected to result from
clearing. Accumulations of thick dust on vegetation
can potentially retard snov.melt (Drake 1981). The
vegetation types which will be affected by dust in
the Watana area include woodland and open black and
white spruce, mixed forest types and shrubl and. The
direct effect of dust on plants varies with plant
species and the chemical composition of dust. For
example, densities of cottongrass (Eriophorum spp.)
are likely to increase. but stiff clubmoss, sphagnum
E-3-226
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3 -BOTANICAL RESOURCES
( i v)
(v)
(vi)
(vii)
moss, and some fructicose 1 tchens may decrease in
abundance when exposed to dust {CRREL 1980). Mosses
and 1 i chens are important components of the ground
cover in open and woodland spruce and closed mat and
cushion tundra stands (see Section 3.2.2).
Effects of Altered Drainage
Local alteration of drainage patterns and surface
water regimes may result from clearing, ditching, and
other construction activities. Blocking drainage
patterns may cause waterlogging of soils, thermal and
hydraulic erosion, and shifts of surface flow to
adjacent drainages (CRREL 1980). Resulting changes
in surface water regimes will cause plant communities
to shift accordingly. The time required for these
changes to occur, and the extent of the change, will
depend on the extent of hydrologic alterations and on
plant successional dynamics (Neiland and Viereck
1977).
Effects of Change in Albedo
Cleared soils usually absorb more solar radiation
than do vegetated soils and consequently thaw sooner
in spring and deeper over the summer. Converse 1 y,
with less insulation soils freeze earlier and deeper
in the winter. Resulting changes in surface
hydrology will cause plant communities to change.
Indirect Consequences of Vegetation Removal
Methods of vegetation removal may have indirect
impacts on other vegetation. Spruce budworm disease,
which occurs in areas adjacent to the Susitna water-
shed (Hegg 1970), may be more likely to invade the
area if spruce trees are cut but not removed or
burned. Clearing may also enable other insects and
decay organisms to increase in abundance (Kimmey and
Stevenson 19~7).
Effects of Increased Fires
The increased numbers of people in the area during
the construction period may cause increased inci-
dences of fires. Fire has been a natural factor
shaping plant communities in the area, so increased
fires will cause changes in plant communities similar
to those that can already be observed there.
E-3-227
3 -BOTANICAL RESOURCES
Because successional
related fires are more
during the operations
Section 3.3.1(b).
(b) Filling and Operation
patterns following project-
likely to manifest themselves
phase, they are discussed in
The Watana facility is scheduled to begin filling in 1990.
Some construction-related impacts such as fugitive dust will
diminish, but other problems such as erosion will continue.
The most conspicuous filling and operation-related changes
in vegetation will be downstream as a result of streamflow
regulation, but less drastic changes may be caused by micro-
and mesoclimatic changes, increased fire incidence, and
increased off-road vehicle (ORV) use. In many instances,
vegetation wi 11 respond to these disturbances through char-
acteristic successional recovery patterns. The following
subsections describe filling and operation-related changes
and the successional patterns of plant communities as they
recover from development-induced change.
(i) Vegetation Succession Following Removal
On sites where vegetation has been removed, natural
plant succession will occur unless prevented by inun-
dation or facility maintenance. Successional pat-
terns expected in forests, shrublands, and tundra are
discussed below.
-Forest Areas and Shrubland
Within forest and shrubland areas, newly cleared
sites with largely intact mineral and organic soils
wi 11 rapidly revegetate with plants native to the
original community. Herbs, shrubs, and deciduous
trees wi 11 resprout, and some herbs and shrubs will
regenerate from buried seed (Nei 1 and and Viereck
1977, VanCleve and Viereck 1981, Conn and Delapp
1982a, b).
In interior Alaska, characteristic early succes-
sional herbs and shrubs are bluejoint reedgrass,
field horsetail, prickly rose, bluebell, bunch-
berry, northern bedstraw, Labrador tea, American
twinflower, goosefoot, pale corydalis, American
dragonhead, fi reweed, crazyweed, and rough
cinquefoil. Early successional trees are willow,
aspen, and poplar.
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From 6 to 25 years after clearing, will ow and/or
alder will typically dominate areas that were
originally black spruce forest or shrubland (see
reviews of forest succession by Neiland and Viereck
1977, VanCleve and Viereck 1981). McKendrick et
al. (1982) found that typical heights for willow
and alder between 3 to 6 years old were 15 inches
(60 em) and 68 inches (170 em), respectively. Soon
thereafter a tree canopy of young black spruce,
willow, and alder will develop. Dense stands of
spruce with well-developed moss and 1 ichen compo-
nents will not develop for 50 to 100 years. Mature
black spruce trees in typical 100 year old stands
usually do not exceed 45 feet (15m) in height.
-Tundra
Clearing of tundra and concurrent removal of top-
soil will, except in certain rocky alpine sites,
typically result in higher soil temperatures and,
if permafrost is present, a deeper thaw (Bliss and
Wein 1972, Hernandez 1973, Gersper and Chall inor
1975, Chapin and Shaver 1981). Either of these
conditions may lead to the development of a dif-
ferent plant community from that originally present
and possibly a very long restoration period. One
to several centuries may be required for recovery
from disturbance where the topsoil is lost (Brown
et al. 1978). But if topsoil is retained, recovery
to the same community type can be rapid. The top-
soils contain most of the available nutrients,
rhizomes, and seeds required for rapid recoloniza-
tion (see discussion by Chapin and VanCleve 1978).
Although natural successional trends of tundra are
far 1 ess predictable than for forested areas, the
following sequence is likely to occur. The first
vegetation types to reestablish in moist or wet
tundra (with the organic layer retained) are likely
to be cottongrass species and, if buried seed is
present, sedges on wet sites. Grasses may predomi-
nate on drier sites (see Chapin and Chapin 1980,
Chapin and Shaver 1981, Gartner 1982). Within 5 to
10 years after normal revegetation begins, at least
50 percent and often 100 percent of v~getation
cover recurs on sites on which the original organic
layer was retained. Native woody and herbaceous
species characteristic of adjacent areas will also
begin to invade within 10 years; likely species in
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3 -BOTANICAL RESOURCES
the project area include willows, bog blueberry,
mountain cranberry, northern Labrador tea, shrubby
cinquefoil, prickly rose, field oxytrope, lupine,
green alder, and dwarf and resin birch. Reestab-
lishment of normal densities, however, may require
several decades.
(ii) Effects of Erosion and Deposition
If the drawdown zone of the Watana impoundment is
typical of that of other northern reservoirs, it will
remain unstable until bedrock or gravel/cobble/
boulder substrates are exposed. The drawdown zone
will remain essentially unvegetated. This will
result in an unvegetated area between the elevations
of 2095 feet and 2185 feet ( 639 m and 666 m) along
the reservoir. (Range equals 90 feet [27 m] as shown
by the rule curve for Watana Reservoir, Ex hi bit B,
Figure B.53). Shoreline recession is likely, with
consequent loss of vegetation {Baxter and Glaude
1980). Except during a series of drought years,
vegetation is not expected to invade the drawdown
zone, and no effects on vegetation from ice shelving
are anticipated. Although some of the evolving
shoreline above the drawdown zone will be readily
colonized by early seral stages such as grasses and
herbaceous species, stabilization of this upper
shoreline may require 30 years or more {Newbury and
Malaher 1972).
After the reservoir is fi 11 ed, the water wi 11 warm
adjacent hillsides, causing permafrost to melt and
slides to occur. On the south side of the Watana
impoundment, the permafrost layer is 200 to 300 feet
(60 to 90 m) thick and is within 1.8°F (1°C) of
thawing. Slides and 1 and sl umpages are therefore
likely on the south side of the reservoir. If these
slides are small and the organic soil layers have not
been lost, encroachment by rhizomatous species may
enable rapid recolonization. If large slides occur,
a full cycle of forest succession on mel ted perma-
frost may ensue, 1 eading to black spruce and bog
vegetation over 100 to 200 years.
Following beach (mudflat) development, flooding of
upland areas may occasionally occur as a result of
water displacement from slumpage (Kerr 1973) and
during high flows. This occasional flooding of
adjacent areas will likely stimulate new vegetation
growth. Propagation of deltas into the reservoir at
E-3-230
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3 -BOTANICAL RESOURCES
a number of creek tributary mouths is 1 i kel y si nee
deposition wi 11 occur when fast creek currents empty
into slow-moving reservoir water. These deltas may
eventually be vegetated in the same manner as down-
stream floodplain areas (see discussion below).
(iii) Effects of Regulated Flows
A mosaic of plant communities in various stages of
floodplain succession is found in the floodplain of
the Susitna River. This diversity is the result of
processes of vegetative recession; the replacement of
an established plant community with a younger
community. Vegetative recession results from changes
in river morphology, which is controlled in the
Susitna River floodplain primarily by ice processes
and flooding events. These processes are effective
mainly during river freezeup and breakup. To a
lesser degree, vegetative recession also results from
bank erosion and deposition of bed material through-
out the open water period, but this is a minor,
localized process in the Susitna River floodplain.
Figure E.3.78 illustrates patterns of vegetation
succession.
The effects of regula ted flows on vegetation at a
particular location will vary considerably with
channel morphology and the distance downstream from
the Watana dam. Potential impacts on floodplain
vegetation will be discussed separately for the river
reaches between Watana and Devil Canyon, Devil Canyon
to Talkeetna, Talkeetna to the Yentna River, and from
there to Cook Inlet. Additional information on
channel morphology and changes in the hydrologic
regime can be found in Chapter 2, Sections 2.1 and
3.2.3.
-Watana to Devil Canyon
(RM 184 to RM 152)
This reach of the river is mostly a single channel
with steep armored banks and bedrock outcroppi ngs.
The two dominant processes presently controlling
vegetative recession are ice scouring at river
freezeup and at breakup.
During river freezeup, the steep gradient of the
river stretch restricts ice formation to the
borders of the river channel in most areas (see
Chapter 2). Growth of border ice and ice in the
center of the channel of slower reaches results in
increased stage. Buoyant forces on the border ice
E-3-231
3 -BOTANICAL RESOURCES
resulting from increased staging cause scouring of
attached vegetation as the ice fractures, rises,
and disintegrates. In addition, ice blockage in
the channel can result in ice scouring of vegeta-
tion higher on the banks and islands and can also
cause the river to overflow into side channels
where additional scouring of bed materials and
vegetation occurs.
The effects of river breakup on vegetation are
greatest when breakup occurs rapidly before exten-
sive in-place melting and deterioration (rotting)
occurs and in association with high spring flows.
Ice jamming in spring at constricted points has
effects similar to those occurring at freezeup but
can have much more dramatic 1 ocal effects due to
the typically higher discharges which occur during
breakup.
The increased temperatures of the water released
from Watana in winter will preclude the formation
of an ice cover in this reach. In addition, the
mean annual flood will be reduced by 75 percent to
12,000 cfs. These changes will result in vegeta-
tion encroachment toward the main channel, the
establishment of vegetation in overflow channels
and newly-exposed areas with adequate soils, and
the gradual succession of existing and newly-
established vegetation stands along the bank and on
islands to mature poplar and white spruce forest.
Although the rate of vegetative recession may be
reduced by as much as 90 percent, the amount of
area affected will be 1 imi ted by the steep banks
and poor substrates found throughout most of this
reach.
The open-water area in winter may promote ice fog
conditions and rime ice formation on vegetation,
particularly at the dam outflow. Buildup of rime
ice may result in loads sufficient to break twigs.
Birch trees may be particularly susceptible to this
damage because of their many small branches.
Sapling tree stands heavily damaged by ice have
been found to produce more brush, whereas ice
damage in mixed oak tree stands resulted in loss of
understory saplings and low tree branches (Wood et
al. 1975).
E-3-232
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-Devil Canyon to Talkeetna
RM 152 to RM 97)
The Susitna River in this reach comprises alter-
nately single channel and split channel configura-
tions •. The channel is armored with boulders and
cobbles and alignment has changed little since
1951. A comparison of aerial photographs taken in
1951 with those taken in 1980 showed vegetative
recession resulting from shifts in the outermost
banks of the river. The photography did not allow
an estimation of the actual areas affected. The
rate of .~egetative recession is controlled
primarily by ice processes during freezeup and
breakup, with summer flooding events having a
lesser but important effect. R&M (1982} listed
sever a 1 1 ocat ions in this reach where chan ne 1 con-
strictions cause recurrent ice jamming during
breakup. Vegetation patterns just upstream from
these locations are influenced primarily by ice
scouring during breakup, but along the majority of
this reach ice processes accompanying river freeze-
up appear to have the greatest influence on vegeta-
tive recession. The fact that the vegetation line
at a point 0.5 mi (18 km) upstream from Gold Creek
(RM 136.8) is at the same elevation as ice staging
during freezeup in fall 1980 is evidence of the
influence of ice scouring during breakup in this
reach {T. Lavender 1982 pers. comm.).
The mean annual flood at Gold Creek will be reduced
from 49,500 cfs to 12,000 cfs by the Watana
project. Ice will still form in this reach, but
the ice front at the end of winter is expected to
occur between Portage Creek (RM 149) and Curry (RM
120.5), and its formation there will be delayed by
3 to 4 weeks (see Chapter 2, Section 3.2.3).
Because air temperatures will be lower once ice
formation begins, the ice layer will progress more
rapidly than it does under pre-project conditions.
Regulated winter flows at Gold Creek will be
similar to existing conditions during filling, but
during operation will be at least five times
greater than pre-project winter flows {Chapter 2,
Section 3.2.3). This will result in a 3 to 4 foot
increase in river stage over existing conditions
when an ice cover is present in this reach. During
the early years of the operation phase, this
increased ice staging will scour existing stands of
E-2-233
3 -BOTANICAL RESOURCES
vegetation, thus causing an increase in the width
of the unvegetated channel and a decrease in the
amount of vegetation found on islands. Because
spring flood stage will be reduced considerably and
because the ice cover will no longer have a greater
tendency to melt in place, ice scouring during
breakup wi 11 no 1 anger be an important factor
causing vegetative recession in this reach. The
area affected by these post-project processes will
be directly related to winter flow releases, which
wi 11 vary between 5,000 -19,300 cfs depending on
downstream flow requirements, powe.r demand, reser-
voir operating rule curve, and attenuation of
discharge due to floodplain storage capacity.
-Talkeetna to Yentna River
(RM 97 to RM 28)
There is a dramatic change in the morphology of the
Susitna River from a split channel to a braided
channel at the confluence of the Susitna, Chulitna,
and Ta 1 keetna Rivers. The flows contributed by
each of these rivers at the confluence are 40
percent each for the Chulitna and Sus itna Rivers,
and 20 percent for the Talkeetna River.
Downstream from Talkeetna, the importance of ice
processes in vegetative recession is reduced, and
large changes in channel position and form pre-
sently occur whenever the river attains bankfull
stage. The importance of ice processes in vegeta-
tive recession in this reach is local and depends
on channel morphology.
Upstream from channel constrictions, ice processes
during freezeup and breakup may continue to play a
major role in regulating vegetative recession. If
ice processes cause greatly increased stages during
either freezeup or breakup at such a constricted
point, vegetation immediately upstream and/or along
overflow channels may be scoured by water and ice
action. This increased staging at channel con-
strictions may occur even at rel at i vel y 1 ow flows.
However, because of the localized importance of ice
processes, summer flood events may control vegeta-
tive recession as much as ice processes associated
with freezeup through their effect on the rate of
bank erosion and sediment deposition in this reach.
Where the floodplain is wide with braided channels,
there is generally a relatively small increase in
E-3-234
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stage when an ice cover is present, and ice proces-
ses have a lesser effect on vegetative recession.
In such areas, numerous islands with mature forest
stands are present.
It is imposs'ible to predict with certainty the
vegetation changes that will occur post-project in
this reach. The bankfull flood will have a post-
project recurrence interval of once every 5 to 10
years, as opposed to the present 2-year interval
(R&M 1982). In areas where such floods control the
vegetation, early-successional stands may develop
for about 5 to 10 years before being removed by the
next bankfull flood. In same of these stands,
however, silt deposition or vegetation growfh may
be rapid enough to stabilize the area against
subsequent floods. Increased winter flows with
subsequent increases in ice staging may cause other
areas to undergo regular ice scouring during
freezeup. The amount of area supporting mature
stands of vegetation will be directly influenced by
floods and the flow releases from Watana each
winter.
-Yentna River to Cook Inlet
{RM 28 to RM Q)
The Yentna River contributes about 40 percent of
the mean annual flow entering Cook inlet from the
Susitna River. Between the Yentna confluence at RM
28 and the beginning of the delta at RM 20 (Figure
E.3.3), the bankfull flows (80 percent of which are
contributed from rivers other than the Susitna 'UP-
stream from Talkeetna) are probably the dominant
factor in controlling vegetative recession. The
river begins to branch out into its delta channels
at RM 20. The water surface elevation at this
point is. approximately 30 feet (9.lm), which ·corre-
sponds to be the 30-foot (9.1-m) tides in Cook
Inlet.
Post-project changes in vegetation cannot be pre-
cisely predicted, but should be substantially
mediated by the large flow contribution from the
Yentna River and the tidal influence as far north
,as RM 20. As R&M (1982) state, 11 the dilution
effect of major and minor tributaries as well as
the balancing of changes by the Susitna River
system should mask any measurable changes that
could occur as a result of the pr'.aj•ect for several
decades ...
E-3-235
3 -BOTANICAL RESOURCES
(iv) Climatic Changes and Effects on Vegetation
Reservoirs act as a heat source or sink, warming and
cooling less rapidly than the surrounding terrestrial
substrate. These effects may delay the normal spring
warming and fall cooling of adjacent environments and
so affect the phenology and di stri but ion of nearby
vegetation. Temperature effects most 1 i kel y would
not extend beyond 2 miles (3.0 km) of the water mass.
Due to the prevailing northeasterly winds, the area
along the south shore of the reservoir would be most
likely affected. Vegetation types in this area
consist mainly of open and woodland black spruce,
open mixed forest, and a limited amount of shrubland.
Crowberry, Labrador tea, blueberry, willow, and
mountain cranberry are important components of the
shrub layers of these types and would be the species
to be affected by changes in timing of bud break or
flowering.
Spring air temperatures in the immediate vicinity of
the reservoir will be cooler on the average than at
present. The cumulative effects of a cooler spring
environment on the entire plant community are not
well understood. Phenology studies are now in pro-
gress to determine the pattern of greenup near the
proposed impoundment. Results from 1982 wi 11 be
reported in April 1983.
The Watana impoundment should act as a heat source in
fall, maintaining slightly warmer air temperatures
than normal. The probable effects of this warming on
vegetation cannot be predicted with any certainty.
For example, it is not known how local climatic
changes will affect characteristics of the growing
season.
Another thermal effect of the Watana impoundment will
be its moderation of diurnal changes such that nearby
nighttime temperatures during May and June wi 11 be
higher and daytime temperatures will be lower than
prior to development. Average fall temperatures near
a 1 ake of similar size to the Watana reservoir were
characterized by a 9.9°f (5.5°C) lower maximum and
4.0°F (2.2°C) higher minimum than temperatures away
from the lake (Baxter and Glaude 1980). The effects
of these thermal changes on the vegetation are,
again, difficult to predict in any quantitative way.
During winter, the development of extensive fog banks
near the Watana impoundment may a1 so affect
E-3-236
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(v)
vegetation. Fog banks tend to be persistent at
reservoir sites after breakup (Baxter and Glaude
1980), and can result in the deposition of copious
~uantities of hoar frost on trees and shrubs.
Buckler (1973) reported that ice crystals 2 to 3 in
(5 to 7 em) in length were found on vegetation close
to a reservoir when temperatures below -9.4°F (-23°C)
created steam fog. Such buildup of ice may result in
damage to understory or reduction in browse quality
or availability (see Section 3.3.1(b)[iii]).
Effects of Increased Human Use
During the filling and operation stages of the Watana
facilHy, project personnel and their families will
have an impact on the vegetation of the middle
Susitna bas-in. The most severe human-use impacts
will probably be associated with off-road vehicles
(ORVs) and accidental fires, assuming that no regula-
tion of project personnel is enforced to mitigate
these impacts. Similar but more extensive impacts
are expected from use by the general public and are
discussed in Section 3.3.3 Access.
-Off-Road Vehicles
The effects on vegetation of ORV use varies with
season, soi 1 moisture and depth, the presence or
absence of permafrost, vehicle weight, frequency of
use, and other factors (Chapin and Van Cleve 1978,
Sparrow et al. 1978).
The ground layer of vegetation is more susceptible
to damage by ORVs than are other 1 ayers. Vegeta-
tion is most susceptible to damage in summer. In
winter, snow and ice layers minimize damage to the
underlying vegetation and organic mat. Dry habi-
tats are relatively immune to damage by ORVs. A
few passes of light-track vehicles over relatively
dry well-drained soils may result in slight compac-
tion of the organic and/or plant layer, a net soil
temperature gain, and deeper thaw of the active
soil layer. The typical result is minor subsidence
and an influx of ground water.
Tundra and wetlands, especially sites with under-
lying permafrost, are the most vulnerable habitats.
Repetitive off-road traffic or use of heavy ve-
hicles in moist areas is likely to remove vegeta-
tion and also the underlying organic mat. This
E-3-237
3 -BOTANICAL RESOURCES
would cause soil temperature increases, deeper
thaw, subsidence to 3 feet (1m) or more, ground-
water input, and severe erosion that may last 5 to
50 years or more (Hok 1969, Rickard 1972, Lawson et
al. 1978, Chapin and Shaver 1981). Quagmires may
form as a result of ponding of surface water
(Sparrow et al. 1978), or gully formation may
result. Near the Denali Highway, Sparrow et al.
(1978) observed gullies formed after ORV use as
wide as 20 to 26 feet (6 to 8 m) and up to 10 feet
(3 m) deep, with severe side erosion and cave-ins,
as well as active transport of sediment downhill.
A similar effect was noted when firel ines were
established on Wickersham Dome, near Fairbanks
(Lotspeich 1979). The above effects will be most
severe where ground ice content is high (Bliss and
Wein 1972). Natural restoration of the organic
layer of tundra soils may require more than a cen-
tury (Chapin and Van Cleve 1978). However, some
grasses, such as bluejoint reedgrass, may be able
to invade mineral substrates rapidly (Gartner
1982).
-Fires
Although the results of tundra fires are extremely
variable, in most cases all signs of the fire have
disappeared after 6 to 8 years. Recovery can take
much 1 onger in areas with abundant 1 i chen cover
(Viereck and Schandelmeier 1980). In shrubland and
forest, a variety of successional patterns might
result from a fire, depending on fire intensity and
burning patterns, vegetation type, soil moisture
and temperature, time of year, and post-fire
weather patterns (Figure E.3.77). For example,
some willow species, while highly adapted for re-
seeding burned areas, produce seeds that are viable
for only short periods of time in the spring or
fall (Zasada and Viereck 1975, Zasada and Densmore
1977).
Trees and shrubs, including aspen, birch, willow
and alder, resprout and grow vigorously after
burns. Shallow-rooted shrubs such as cranberry are
destroyed in areas heavily burned to mineral soil;
however, burning to mineral soil is necessary for
establishment of willow seedlings (Densmore and
Zasada 1977, Densmore 1979). In the short term,
increased productivity of browse plants such as
willow, aspen, and birch is likely as a result of
the release of soil nutrients (Figure E.3.117).
Many berry producing plants also increase in den-
sity after fire (Friedman 1981).
E-3-238
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The ecological effects of fire on Alaskan vegeta-
tion have· received considerable attention during
recent years, and the accumulated knowledge allows
a degree of prediction of the effects of a given
type of fire on a specific area. (This knowledge
plus increasingly effective fire control methods
have resulted in fire being used as a land manage-
ment tool to create desired vegetation changes --
Section 3.4).
Wi 1 dfi re is a common and natura 1 phenomenon
throughout the needleleaf forests of interior
Alaska. Characteristics affected by fire in these
forests include: live biomass, dead and decaying
biomass, available nutrients, soil temperature and
soil moisture. Fire in black spruce forest greatly
reduces the overstory biomass, although standing
dead snags may persist. Burning may partially or
completely oxidize organic constituents of the
forest floor, releasing large quantities of avail-
able nutrients such as phosphorus. Soi 1 tempera-
tures become warmer through enhanced absorption of
solar radiation. Permafrost, where present,
recedes because of severa.l factors including
changes in albedo and loss of vegetative insula-
t ion. Thus the active layer significantly
increases in depth {Viereck and Schandelmeier
1980).
Fire generally causes vegetation to revert to an
earlier successional stage. The primary effect of
increased fire frequency in the coniferous commun-
ities of, the Susitna Basin will be to change the
veg.etation to earlier herb or shrub seral stages,
si gnifi cantl y increasing avail able moose browse on
those areas (Figure E.3.117).
Coniferous forests usually revert to a herbaceous
or shrub stage (Foote 1979) characterized by rapid
nutrient turnover, high productivity, and rel a-
tively high decomposition rates (Viereck and
Schandelmeier 1980).
Production of moose browse, especially wi 11 ow, is
often very high during the shrub stage. Wolff and
Zasada (1979) found th.at 3 to 7 years .after a fire
in black spruce forest, the amount of wi ll'ow browse
available to moose increa-sed 680 percent from 6.5
to 44.1 kg/ha. The Bureau of Land Management
(unpublished data) reported a 1280 percent increa-se
in wi 11 ow density from 1,800 to 23,000 stems/ha in
7 years following a fire of moderate· intensity in
white spruce.
E-3-239
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3 -BOTANICAL RESOURCES
In constrast to these potentially beneficial
effects of fire on browse and berry production,
negative impacts may also occur as a result of
vegetation removal and consequent soil insta-
bility. Fires on steep slopes result in increased
runoff due to vegetation loss, and may cause mud or
landslides. In other areas thermokarst topography
and gullies may result from fires (Viereck and
Schandelmeier 1980).
3.3.2 -Devil Canyon Development
(a) Construction
(i) Vegetation Removal
Because of the narrow, steep configuration of Devil
Canyon, vegetation losses will be substantially less
than for the Watana Dam. Approximately 5700 acres
(2305 ha) of forest and 170 acres (70 ha) of shrub-
land will be inundated or cleared (Table E.3.84). An
additional 551 acres (223 ha) will be altered or lost
as a result of the camp, village, and borrow areas.
As discussed in the previous section, natural revege-
tation of some disturbed sites will probably occur.
Typical successional sequences reviewed in Section
3.3.1(b)(i) also apply to the Devil Canyon region.
(ii) Vegetation Loss by Erosion
The most likely source of vegetation loss by erosion
at the Devil Canyon site will be rock slides along
steep banks, especially on the south side of the
reservoir. Although most rockfalls wi 11 occur at
elevations of 900 to 1300 feet (274 to 396 m} and
thus will be below the eventual fill level, some
slides may also occur above this zone. Only sporadic
concentrations of permafrost have been found in Devil
Canyon. Resulting erosional problems and vegetation
1 oss through permafrost melting should therefore be
minimal. Clearing may be a significant source of
erosion which may in turn result in further vegeta-
tion loss in adjacent unc1eared areas.
E-3-240
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3 -BOTANICAL RESOURCES
(b)
( i i i )
(iv)
(v)
(vi)
Vegetation Damage by Wind and Oust
Wind-related phenomena such as tree blowdown are less
1 i kely at the Devil Canyon site than at the Watana
site because the maximum fetch will be far less at
Devi 1 Canyon. Dust wi 11 be generated by clearing of
the Devil Canyon impoundment area, but because the
impoundment area is in a narrow valley that is more
protected from wind than the Watana impoundment area,
resulting impacts to vegetation are expected to be
relatively minor.
Effects of Altered Drainage
Excavation and construction activities w"ill impinge
on a number of small 1 akes and ponds south of the
Devil Canyon site. A total of 32 acres {13 ha) are
covered by 1 akes within 10 miles ( 16 km) of the
Susitna River at the Devil Canyon facility. Excava-
tion in these areas may result in the creation of new
aquatic or bog habitat with ensuing development of
bog vegetation (Neiland and Viereck 1977). The steep
configuration of the canyon will 1 imit other changes
in drainage patterns or water table levels. Any
downslope cuts made. during construction may, however,
promote active gully formation and associated vegeta-
tion loss. Proposed Borrow Area K (Figure E.3.37)
may affect an additional 99 acres (40 ha) of poten-
tial wetlands.
Effects of Change in Albedo
Clearing of the Devil Canyon impoundment area will
result in a warming of underlying soils prior to
filling. Since permafrost is not generally present,
impacts on adjacent vegetation will be minimal.
Indirect Consequences of Vegetation Removal
Indirect effects of different clearing methodologies
were reviewed previously for the Watana site (Section
3.3.1(a)). These effects are also applicable to the
Devil Canyon area, although the steep configuration
of the canyon may make recontouri ng and topsoi 1 re-
placement efforts less effective.
Filltng and Operation
The Devil Canyon impoundment will be filled in about two
months. No appreciable downstream effects on vegetation
should be evident during filling. Upstream from the dam,
E-3-241
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3 -BOTANICAL RESOURCES
filling will result in diminished dust in summer and perhaps
will slightly alter microclimate, especially on the windward
side of the reservoir (see Section 3.3.1(b)[iii]).
Because the drawdown zone for the Devil Canyon impoundment
will cover a range of 55 feet (17 m) during most of the year
as shown by the rule curve for Devil Canyon reservoir
(Exhibit B, Figure B. 53), the rise and fall of the water
table will probably affect vegetation only in a narrow band
adjacent to the reservoir. The con so 1 i dated, rocky char-
acter of the substratum wi 11 in most cases limit water
intrusion and soi 1 waterlogging, and few shifts toward wet
or bog vegetation are likely.
Relatively few additional impacts on vegetation are ex,pected
during operation of the Devil Canyon developm~nt. The old
large landslide at River Mile 175 (Figure E.3.3) could move
after filling, temporari~y blocking river flow and flooding
upstream areas. This could cause a loss of mid-and late-
successional vegetation in areas such as the mouths cHJ,d
floodplains of Fog and Tsusena Creeks. Howe_ver, the areal
extent of such impact cannot be reliably predicted.
Meso-and microclimatic effects on vegetation will be very
small and probably well within the range of normal varia-
tion, due to the relatively small size of the reservoir.
(i) Vegetation Succession Following Clearing
The same general vegetational succession patterns
will occur on cleared, unsubmerged lands uf the Devil
Canyon area that were described for the Watana site
(see 3.3.1(b)[i]). However, due to the steep, rocky
character of Devil Canyon a much greater mosaic of
vegetation types may develop. On some slopes, loss
of soil may result in shifts to low-lying alpine
communities dominated bymountain-avens, rather than
a gradual return to shrubland and forests.
(ii) Erosion and Deposition
Due to the geological character of the Devil Canyon
region, erosional/depositional changes affecting
vegetation will be minimal following filling of the
reservoir.
(iii) Effects of Regulated Flows
Downstream effects of the Devil Can.yon dam in the
re.ac hes downstream of Talkeetna, wtl:l .ae similar to
those discussed in Section 3.3'.I(b)(iii). The
E-3-242
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3 -BOTANICAL RESOURCES
factors cantrall i ng vegetation in the De vi 1 Canyon-
Ta"lkeetna reach, however, wi 11 change as a result of
the lack of ice formation in this reach. With Watana
only, the rate of vegetative recession will be con-
trolled primarily by increased ice staging during
freezeup and secondarily by ice scouring at breakup.
The width of the unvegetated floodplain will increase
with a corresponding decrease in the size of
vegetated islands. Once Devil Canyon is operating,
ice scouring will be completely eliminated, and
vegetation w·ill be controlled by peak flows. Since
the peak flows wi 11 have a stage that iS at 1 east 5
feet below that when ice is present, many areas will
be available for primary succession after the con-
struction of the Devil Canyon dam. Succession will
follow the pattern shown in Figure E.3.78.
3.3.3 -Access
(a) Construction
Approximately 477 acres (193 ha) of fJf'imarHy shrub and
tundra vegetation will be cleared along a 44 mi (70 km) cor-
ridor for the Oenal i Hi ghway-to-Watana access route (Table
£.3.85). The vegetation adjacent to the access road will be
subject to indirect effects including dust deposition,
erosion, leaching of nutrients in recently drained regions,
and waterlogging in areas of blocked drainage. These
effects are all discussed in more detail in Section
3.3.1(a).
When the Devil Canyon dam is built, an additional road seg-
ment wi 11 connect the Devil Canyon and Watana sites along a
37 mi (59 km) corridor north of the Susitna River (Figure
37). Construction of this road w.ill entail clearing an
additional 468 acres (189 ha) of roadway. A 12 mi (19 km)
railroad extension between Devil Canyon and Gold Creek will
be constructed on the south side of the Sus itna River,
removing an additional 72 acres (29 ha) of vegetation.
Spruce and mixed forest, tall and low shrubland, and tundra
vegetation types will all be crossed by these corridors
(Table 85).
Many of the same impacts experienced in clearing the Watana
and Devil Canyon impoundments· (Sections 3.1.l(a), and
3.3.2(a)) will occur during and fo1low]n!l. access;..related
clearing. These include erosion, dust deposition, and
drainage changes.
E-3-243
3 -BOTANICAL RESOURCES
(b) Operation
Use of the access roads wi 11 result in continued dust-and
erosion-re 1 a ted effects on vegetation bordering the access
road. In addition, access roads will facilitate increased
human disturbances, including ORV use and a higher incidence
of fire. These disturbances and their impact on vegetation
are discussed in Section 3.3.1(b).
In contrast to the access roads, the proposed rai 1 connec-
tion from Devil Canyon to Gold Creek will minimize off-road
access and fire incidence. The rail connection will pri-
marily traverse spruce and mixed deciduous type forests.
3.3.4 -Transmission Corridors
(a) Construction
Transmission corridor comprise a total of 18,040 acres
(7300 ha) and will consitute another source of vegetation
loss and/or disturbance (Tables E.3.79, E.3.80, and
E.3.86). The transmission lines from Healy to Fairbanks
cover a total of 7106 acres (2876 ha). Open black spruce
(1270 acres, 514 ha) constitutes the main vegetation type in
the right-of-way. The Wi 11 ow-to-Cook Inlet transmission
corridor (total cover 3209 acres, 1299 ha) will cross
primarily closed conifer-deciduous forest (568 acres, 229
ha). The Willow-to-Healy transmission corridor (6184 acres,
2503 ha) is composed primarily of upland (2888 acres, 1169
ha) and lowland (1503 acres, 608 ha) spruce hardwood forest
types. Shrubland (457 acres, 185 ha), tundra (390 acres,
158 ha), and forest (417 acres, 117 ha) are included in the
proposed rights-of-way for the Watana-to-Gol d Creek trans-
mission corridors (total area 1541 acres, 512 ha).
In all the above cases, the vegetation types affected repre-
sent small fractions (less than 4.2 percent) of the total
available vegetation types within the corridors. Of this
portion only a negligible fraction of the vegetation will be
totally eliminated by intermittent placement of control
stations, relay buildings, and towers. The remaining
vegetation will be_subject to selective clearing of trees
and tall shrubs There will be no clearing of low shrub or
tundra types. Thus 1 ow-lying vegetation and small shrubs
will remain largely undisturbed. Such cleared areas have
the potential of increased browse production by willow and
birch shrubs following over-story removal. Transmission
corridor construction is described in Section 3.4.2(a).
E-3-244
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3 -BOTANICAL RESOURCES
(b) Operation
After establishment of the transmission corridors, periodic
maintenance via selective clearing or trimming will be
required. Such manual clipping may stimulate leaf and twig
growth of willow and other browse species (Wolff 1978). On
the other hand, evergreen shrubs such as Labrador tea and
other woody shrubs are likely to show increased mortality if
damaged in the process of clearing (Chapin et al. 1975,
Chapin 1980, Chapin and Shaver 1981). But the potentially
most damaging aspect of operation may be increased ORV use
in the rights-of-way (see Section 3.3.1(b)(v).
3.3.5 -Impacts to Wetlands
(a) Construction
The direct removal of vegetation as a result of construction
and clearing operations relative to the Watana and Devil
Canyon developments have been quantified in Sections
3.3.1(a)(i) and 3.3.2(a)(i). The primary vegetation types
to be removed by the impoundments, dam, and spillways of the
Watana development include stands of woodland and open black
and white spruce forest as well as some open mixed forest
types. Construction of the Devil Canyon facility will
result in the direct loss of forest and shrubland. As indi-
cated in Section 3.2.3 Wetlands, wetland classifications may
also be applied as a second level of classification to many
of the above vegetation types (Table E.3.81). Table E.3.82
i 11 ustrates the areal extent of different potential wetland
vegetation types within the locations which will be affected
by the Watana and Devil Canyon developments. As indicated
previously (Seeton 3.2.3), the estimates of total palustrine
wetland areas shown in the table are extremely liberal and
all values should be considered preliminary.
Far more potential wetland areas are included within the
Watana· development (30,705 acres, 12,341 ha) than occur
within the Devil Canyon project area (4214 acres, 1706 ha)
(Table E.3.82). The proportion of the area occupied by wet-
land types also differs within the two areas. Although
potential palustrine forested areas occupy the greatest
areal extent of wetland types in the Watana faci 1 i ty ( 60
percent of total potential wetlands), this type occupies 48
percent of the potential wetlands to be affected by the
Devil Canyon facility. Because of the configuration of
Devil Canyon, riverine wetland types occupy a greater pro-
portion of the potential wetlands of the Devil Canyon facil-
ity (47 percent) than of the Watana facility (18 percent).
E-3-245
3 -BOTANICAL RESOURCES
Within the Watana development area, about 11 percent of the
potential wetland areas occur within non-impoundment borrow
sites proposed for dam and ancillary facility construction,
whereas about 98 percent of potential wetlands within the
immediate vicinity of the Devi 1 Canyon deve 1 opment occur
within the dam, spillway, and impoundment areas.
Vegetation removal as a result of construction of access
corridors, Watana dam-to-intertie transmission corridors,
and the Healy-to-Fairbanks and Willow-to-Cook Inlet trans-
mission lines has been quantified in Tables E.3.85, E.3.80,
E.3.86, respectively. As indicated in Section 3.2.3, wet-
land classifications may also be applied as a second level
of classificaton to many of the vegetation types of Viereck
and Dyrness {1980). The reader is referred to the above
tables to review impacts to potential wetlands of the access
and transmission corridors, and to Table E.3.82 for a
general review.
3.3.6 -Prioritization of Impact Issues
In this section, impacts to vegetation are prioritized in order
from most important to least important. As discussed in Section
1.2, impacts are prioritized based on resource vulnerability, the
probability of the impact occurring, and the duration of the
impact. Direct 1 osses of vegetation are judged most important
because of the certainty and the permanance of the impact. The
importance of losses of particular vegetation communities is in
proportion to the total acreage lost and in indirect proportion
to the amounts of each type present regionally.
Plant community changes are judged to be 1 ess important than
actual losses. These impacts are less predictable and of a
shorter duration than vegetation losses.
(a) Direct Loss of Vegetation
( i) Watana
Direct losses for the Watana project include 31,300
acres (12,667 ha) of vegetation for the dam, impound-
ment and spillway. An additional 4300 acres (1742
ha) have been designated for use as camp, village,
airstrip, and borrow areas. These potential losses
account for only 1 percent of all _vegetation in the
middle Susitna basin, but 3.6 percent of the vegeta-
tion present in a 20 mile (32 km) wide area spanning
the Susitna River from the mouth of the Maclaren
River to Gold Creek. More importantly, substantial
losses of certain vegetation types will be sustained
E-3-246
IIJif&iffl
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3 -BOTANICAL RESOURCES
during construction of the Watana Dam. Losses of
forested areas may total 8.3 percent of the 20 mile
(16 km) wide area. Losses of open and closed birch
forest will be particularly large, greater than 20
percent for the 20 mile (16 km) wide area. The
1 osses of these forest types wi 11 mean substantia 1
habitat losses for some wildlife, especially black
bear, moose, pine marten, beaver, raptors, small
mammals, and passerine birds.
(ii) Devil Canyon
( ji i)
Direct losses for the Devil Canyon project will
include 5871 acres (2376 ha) of forests, tundra and
shrubl and. Negligible amounts of tundra and shrub-
land {<.05 percent) will be lost, but 0.7 percent of
all forested lands in the middle basin (1.8 percent
of the 10 miles (16 km) area will be affected.
Because of the steepness of Devil Canyon, these
losses are relatively small compared to Watana and
comparatively less important for wildlife. Again,
however, appreciable quantities of closed birch
forest (18.6 percent of the 10 mile, (16 km area)
will be eliminated.
Access Roads
The Watana access road wi 11 result in a 1 oss of
approximately 568 acres {230 ha) of mixed tundra
vegetation types. Additional losses of about 494
acres (200 ha) for access roads and 78 ha (193 acres)
for rail will be utilized for access to the Devil
Canyon facility. These routes will span spruce
forests, tall and low shrubland and tundra vegetation
types. In relation to possible losses from other
aspects of the project, these direct losses are
small.
(iv) Transmission C.orridors
Of the total 18,040 acres {7300 ha) of vegetation on
rights-of..;way for transmission lines, only a small
fraction need be subject to initial clearing since
there will be no cl eari.ng of 1 ow shrub or tundra
types. Access trails for transport of personnel and
materials, plus smaller areas for placement of con-
trol stations, relay buildings, and towers, will need
to be cleared; other portions of the transmission
corridors will only require selective clearing or
top-cutting of tall shrubs and trees.
E-3-247
3 -BOTANICAL RESOURCES
(b) Indirect Loss of Vegetation
Additional losses of vegetation may occur due to erosion,
permafrost melting and subsequent 1 and slides and sl umpage,
ORV use, b 1 owdown of trees and other causes (see Section
3.3.1(a)). While some of these losses will be short-term
with typical vegetational succession ensuing, or with shifts
to new vegetation types for that area, 1 ong-term vegeta-
tional 1 osses enduring for 30 to more than 100 years may
occur on sites of continual erosion, land slumpage, or ORV
use. The amounts that will be lost because of these factors
are small compared to amounts inundated by the reservoirs.
(i) Watana
Indirect losses of vegetation are projected to be
greatest at the Watana site, where large areas on the
south side of the impoundment are underlain by 200 to
300 feet (60 to 90 m) of permafrost at near melting
temperature. Also, because of the expected 1 arge
size of the reservoir, other erosional processes such
as wind erosion, together with effects of dust, may
cause very 1 oca 1 i zed vegetation 1 oss, espec i a 11 y in
wind-exposed areas.
(ii) Devil Canyon
The smaller, steeper nature of Devil Canyon will
severely limit indirect losses of vegetation. Except
for the possibility of one massive flow near River
Mile 175, rock slides occurring above the impoundment
represent the greatest threats and these wi 11 result
in only small scale losses.
(iii) Access Roads
Some indirect loss of vegetation is expected due to
erosion caused by changes in drainage patterns and
dust deposition on the road edges. Increased utili-
zation of ORVs along access roads and road mai nten-
ance may damage adjacent areas.
(iv) Transmission Corridors
Little indirect loss is likely as a result of direct
clearing or construction, but uncontrolled ORV access
could affect vegetation on and adjacent to corridors.
Forests, shrublands, tundra and wetlands are dis-
persed along this area.
E-3-248
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3 -BOTANICAL RESOURCES
(c) Alteration of Vegetation Types
Alteration of vegetation types will be caused by succession,
changes in drainage patterns, altered river flows, and fire.
In many instances, natural succession of cleared or dis-
turbed areas not subject to inundation wi 11 result in vege-
tation type changes. For example, primary herbaceous and
weedy vegetation and secondary shrub growth may follow
clearing of sites. There may be development of fast-growing
algal species and floating vegetation in shallow areas of
the impoundment(s). Successional trends following man-
caused fires are generally predictable. These impact issues
are discussed further in the mitigation section (Section
3.4).
(i) Downstream Floodplain
The most important alteration to result from the
dam(s) will be downstream between Gold Creek and
Talkeetna, where annual spring and summer flooding
and scour by ice jams will be reduced. As a result,
some of the previously pulse-stabilized communities
will mature. The willow and balsam poplar shrub will
change to mature balsam poplar and thence to spruce.
Within the license period, the development of vegeta-
tion on newly exposed banks and islands will proceed
only to the medium and tall shrub stages.
( i i) Watana
One area of potentially important impacts is tundra
vegetation surrounding the Watana Reservoir. Distur-
bance may cause warming of the soil, melting of the
permafrost, and deepening of the active 1 ayer. In
well-drained areas, this may result in increased
growth and productivity by the existing plant com-
munity, but in waterlogged areas a shift to bog
vegetation is likely. If the organic layer is lost
during disturbance, long-term losses of vegetation
may result.
Most forest and shrub areas disturbed near the reser-
voir will recover naturally. The ensuing patterns of
vegetation a 1 succession wi 11 be acce 1 era ted if the
organic layer is retained and if root suckers or
seeds of vegetation remain.
E-3-249
3 -BOTANICAL RESOURCES
(iii) Devil Canyon
Outside the actual impoundment and dam site, very few
alterations of vegetation types are anticipated at
De vi 1 Canyon. Forest types wi 11 be subject to minor
alterations, primarily near borrow sites G and K, and
near camp and village sites. Likewise, changes in
drainage, waterlogging of soil or permafrost melting
will be highly localized because the soil is gener-
ally very rocky and well drained, with only sporadic
occurrences of permafrost. The smaller, steeper
character of Dev"il Canyon will also act to 1 imit
micro-climatic and mesoclimatic alterations.
(iv) Access Roads and Railroads
The access roads between the Devil Canyon and Watana
sites and between Watana and the Denali Highway, as
well as rail construction between Devil Canyon and
Gold Creek, will alter surface drainage patterns and
may induce dust-related alterations in vegetation at
roadsides. The effects of altered drainages have
been summarized above.
(v) Transmission Corridors
Selective clearing or top-cutting of tall vegetation
will result in local shifts in plant types from trees
to shrubs. Wet and moist tundra areas and their
peripheries will be more suscepti b 1 e to water 1 og-
ging by vehicular traffic with subsequent development
of bog species and/or black spruce in place of
cottongrass and shrub species.
3.4 -Mitigation Plan
3.4.1 -Introduction
This mitigation plan addresses the impacts to botanical resources
described in Section 3.3. Mitigation measures for each impact
issue have been developed according to the approach discussed in
Sections 1.2 and 1.3, and are prioritized as follows: avoidance,
minimization, rectification, reduction, and compensation. Miti-
gation measures are described with respect to locations, proce-
dures, and costs. Recommendations by state of Alaska and federal
agencies are reviewed, and their relationship to the mitigation
plan explained.
E-3-250
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3.4 -Mitigation Plan
The mitigation plan is organized as follows:
(a) Section 3.4.2, Option Analysis:
(b)
-The range of available mitigation options is explained for
each of the impact issues prioritized in Section 3.3.6.
-Selected mitigation measures or facilities are described
along with the reasons supporting each selection.
-The extent to which mitigation will be achieved by area
and over time is indicated where available information
allows.
-Residual impact estimates are provided.
-Implementation s~hedul es are presented commensurate with
the level of detail provided by Exhibit C, Construction
Schedule.
-Implementation costs are provided for measures or facili-
ties which are not included as project capital costs
(Section 4.4.3). Project capital costs are described in
Exhibit D.
-Mitigation measures or facilities recommended through
agency consultation are documented. Where such recommen-
dations have been incorporated in the mitigation plan, ex-
planation is provided. Cases where alternative measures
have been adopted are also explained.
-Illustrations of mitigative project design features are
presented.
Section 3.4.3, Mitigation Summary:
-Mitigation measures for botanical resources are summarized
including schedules and cost estimates for future studies
(Table E.3.177).
(c) Section 4.4.4, Agency Consultation (including wildlife):
-Mitigation recommendations provided through agency consul-
tation are summarized, along with reasons for incorpora-
tion of alternative measures where appropriate.
E-3-251
3.4 -Mitigation Plan
Environmental protection guidelines provided to project engineers
are shown in Appendix 3.B. A majority of these recommendations
have been incorporated into engineering design and construction
planning, resulting in modifications to avoid or minimize adverse
impacts to botanical resources during project construction and
operation. These measures include changes in facility siting and
layout, realignment of access roads and transmission corridors,
alterations in road design and construction, and constraints on
gravel extraction locations and procedures. Because removal of
vegetation will produce the greatest direct impact to botanical
resources of the project area, measures to m1n1m1ze the areal
extent of vegetation removal are treated in greatest detail in
the following discussions.
Rectification of adverse impacts to wetlands has also received
particular attention, especially with regard to correcting block-
age of sheet flow and siltation conditions caused by construction
of access and service roads. Rehabilitation measures to rectify
vegetation and soil loss at temporary construction sites and bor-
row areas have also been incorporated, including procedures to
conserve and replace soils and to revegetate disturbed areas.
Project planning has emphasized the reduction of adverse impacts
to wetlands and downstream riparian vegetation during construc-
tion and operation through monitoring and corrective measures to
be implemented during the license period. Measures to compensate
for impacts to vegetation reflect the importance of botanical
resources as components of wildlife habitat, and have been
designed primarily to mitigate impacts t~ wildlife through habi-
tat enhancement and replacement. Thus, the mitigation plans for
botani ca 1 resources and wildlife complement each other, and mea-
sures designed largely to reduce or compensate for loss of wild-
life habitat are discussed more fully in Section 4.4.
As the Power Authority continues to sponsor field studies to re-
fine and further quantify information obtained during the past
three years of baseline and impact research, and as engineering
design and construction planning proceed, features of this miti-
gation plan will be correspondingly refined with respect to spe-
cific locations, procedures, and costs.
3.4.2 -Option Analysis
(a) Direct Loss of Vegetation
Without mitigation, construction of all project facilities
would remove vegetation from a total of about 68,537 acres
{27,744 ha), apportioned as follows:
E-3-252
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3.4 -Mitigation Plan
acres hectares
-Dams and spillways
-Impoundments
-Camps
-Villages
-Airstrip
-Damsite borrow areas
-Access borrow areas
-Access routes
-Transmission corridors*
274
44,292
245
269
42
4,325
35
1,015
18,040
* Ground layer and soil not removed.
111
17,932
99.
109
17
1, 751
14
411
7,300
Of this cumulatt~e impact, vegetation removal resulting from
dams and spillways, impoundments, access routes, and the
Watana operational village will be permanent, accounting for
about 70 percent (45,581 acres, 18,454 ha). The remaining
30 percent (19,236 acres, 7788 ha) will allow application of
the following range of mitigation options:
-Avoidance: Vegetation·removal cannot be entirely avoided.
-Minimization: This measure is feasible by reducing clear-
ing requirements. Options include:
Minimizing facility dimensions;
• Consolidating structures;
• Siting facilities in areas of low biomass;
Siting facilities to minimize clearing of less
abundant vegetation types;
• Siting facilities to minimize clearing of vegetation
types productive as wildlife habitat components;
• Minimizing volume requirements for borrow extraction;
• Disposal of spoil within the impoundments or previously
excavated areas; and
• Designing transmission corridors to allow selective
cutting of trees and to accommodate uncleared low shrub
and tundra vegetation types within the rights-of-way.
E-3-253
3.4 -Mitigation Plan
-Rectification: Site rehabilitation measures can rectify
impacts of vegetation removal. Options include:
• Dismantling nonessential structures as soon as they are
vacated;
Storing removed organic layer and mineral soil for sub-
sequent replacement;
• Scarification and fertilization; and
• Artificial seeding.
-Reduction: Impacts of construction-related vegetation re-
moval can be reduced over time by:
• Monitoring progress of site rehabilitation to identify
locations requiring repeated application of fertilizer
and/or seed;
• Systematically identifying and rehabilitating areas
where construction activities have ceased and are no
longer required.
Coordinating rehabilitation efforts with closure or re-
moval of service roads no longer required.
-Compensation: This approach is feasible through the ac-
quisition and management of replacement lands. Options
include:
• Acquiring lands with areal coverages of vegetation types
equivalent to those lost, and protecting these lands
from future development •
• Prioritizing lost vegetation types relative to value as
wildlife habitat, and selectively changing vegetation on
acquired lands to replace or exceed lost areal coverages
of the high-priority vegetation types.
(i) Minimization
All of the minimization options summarized above will
be applied to reduce clearing requirements to the least
necessary for project construction. Dimensions of the
construction camps and villages have been kept small by
designing compact arrays of uniformly-sized, contiguous
residential modules, as shown in Exhibit F, Plates F36,
E-3-254
r-'1
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3.4 -Mitigation Plan
F37, F71, and F72. This approach has afforded signifi-
cant structural consolidation, enhanced by combining
the permanent village or townsite with the temporary
construction village at Watana (Exhibit F, Plate F36).
Structural consolidation has been achieved further by
confining the entire infrastructure of camps, villages,
temporary roads, fuel and equipment storage areas, and
other construction support facilities to the vicinity
of the damsite. At Watana, the construction camp is
sited about 2.5 miles {4 km) and the village about 1
mile (1.6 km) northeast from the emergency spillway
(Exhibit F, Plate F3). At Devil Canyon, the construc-
tion village is about 2.7 miles (4.3 km) and the con-
struction camp about 1.5 miles (2.4 km) west from the
emergency spillway, and the railhead pad (approximately
2500 by 800 feet) is about 1. 5 miles ( 2. 4 km) to the
southwest {Exhibit F, Plate F70). These siting
arrangements have been determined primarily by the
nearest available flat terrain to the damsites.
A major consolidation feature incorporated into project
design is the common corridor of the Watana-to-Go 1 d
Creek access and transmission routes {Figures E.3.37,
E.3.39, and E.3.40). Vegetation removal required for
both facilities will affect approximately similar plant
communities in approximately the same locations (com-
pare Tables E.3.80 and E.3.85, and see Figures E.3.39
and E.3.40). Consolidation of the two routes will min-
imize traffic-related vegetation removal by reducing
distances required for transport of equipment from the
nearest road to the transmission corridor. In the
stretch between Watana and Devil Canyon, the adjacent
access road will allow direct overland entry of equip-
ment across a distance ranging from about 0.1 to 0. 75
miles (up to 1.2 km). Equipment will be mounted on
flat-tread, balloon-tire vehicles to minimize soil or
ground-cover disturbance.
Further consolidation has been achieved by siting bor-
row areas which may be required for access road con-
struction immediately adjacent to the route. As shown
in Figure E.3.37, 14 borrow areas have been identified
along the access' route from the Denali Highway to Devil
Canyon. Access routing has been refined to emphasize
well-drained soils which will allow maximum use of
side-borrow techniques in level terrain and balanced
E-3-255
3.4-Mitigation Plan
cut-and-fill in sidehill cut areas (Figure E.3.83).
Therefore, the borrow areas shown in Figure E.3.37 are
not expected to be fully excavated, as they wi 11 be
used only to augment material requirements where side-
borrow or ba1 anced cut-and-fi 11 techniques cannot be
fully utilized. In general, it is expected that each
site wi 11 be excavated at most to a depth of 8 feet
(2.5 m) and will range in area from less than 10 to no
more than 20 acres (4 to 8 ha).
By minimizing gravel extraction requirements and util-
izing borrow areas which, if necessary, will be sited
immediately adjacent to the access road, the need for-
individual access roads to borrow areas has been elim-
inated, further reducing requirements for vegetation
removal.
Facility siting has emphasized areas of low biomass.
The Watana construction camp and village have been
sited in low shrub types (birch and mixed; see Table
E.3.83); these have relatively low clearing require-
ments in comparison to the open mixed forest and tall
shrub stands also in the vicinity, which have been
avoided (Figure E.3.40). At Devil Canyon, the camp and
village have been sited in comparatively well-drained,
closed, conifer-deciduous forest (Table E.3.84) to
avoid nearby low, wet areas of black spruce and wet
sedge-grass (Figure E.3.39). Hence, the Devil Canyon
ancillary facilities will remove more biomass than
facilities of equivalent area at Watana.
Minimizing clearing requirements has been a major con-
sideration in the siting of access roads, particularly
the Denali Highway-to-Watana section where completion
within the first year of construction, 1985, is re-
quired (Exhibit C, Figure C.1; Exhibit E, Chapter 10,
Section 2.3.7[b]). The Denali Highway-to-Watana route
will remove about 343 acres (139 ha) of shrubland and
about 132 acres (53 ha) of tundra types, accounting for
about 0.1 percent of total shrubland in the Watana and
Gold Creek watersheds and a 1 ower percentage of total
tundra cover (Table E.3.85). Only 0.9 acres (0.3 ha)
of open white spruce forest will be affected, and the
number of individual trees actually cut in this low-
density vegetation type will be statistically insignif-
icant on a local or regional basis.
Opposition to the Denali Hi ghway-to-Watana route has
been stated in letters from the ADF&G (1980, 1982), the
E-3-256
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' I
3.4 -Mitigation Plan
the Susitna Hydroelectric Steering Committee (1981),
and the USFWS (1982, 1983). The major wildlife concern
expressed is that habitat for caribou, moose, brown
bear, and black bear will be crossed by this access
alternative. The route has been selected because of
the scheduling requirement cited above for completion
of access to Watana during the first year of construc-
tion. This route is discussed further below and in
Section 3.4.2(b), and in the fish and wildlife impact
and mitigation discussions, Sections 2.3, 2.4, 4.3, and
4.4, respectively.
The Watana-to-Devil Canyon route also is characterized
by vegetation types of predominantly 1 ow bi amass, a 1-
though it crosses a greater variety of plant communi-
ties. Abou~ 48 percent of the route is shrubland (224
acres, 91 ha), 32 percent is tundra (151 acres, 61 ha),
and 20 percent is forest (92 acres, 37 ha) (Table
E.3.85). This routing has been recommended by the
ADF&G (1980), the Susitna Hydroelectric Steering
Committee (1981), and the USFWS (1982). The route has
been incorporated as recommended, and is discussed
further below and in Sections 3.4.2(b), 4.3, and 4.4.
The Devil Canyon-to-Gold Creek railroad route will
traverse almost entirely closed mixed forest (about 50
acres, 20 ha) and open mixed forest (about 14 acres, 6
ha) (Tab 1 e E. 3. 85). In this case, constraints imposed
by criteria for maximum 2. 5 percent grades and
10-degree horizontal curves have necessitated routing
through a heavi er-bi amass vegetation type. However,
the rail mode is itself a mitigation measure in this
respect, because clearing width (50 feet, 15m) is less
than half that required for road construction (120
feet, 37 m).
Rail access to at least Devil Canyon, and preferably
excluding a road system connecting with Alaska high-
ways, has been recommended by the Susitna Hydroelectric
Steering Commmittee (1981) and the u.s. Fish and Wild-
life Service (1982). The rail mode has been incorpor-
ated as recommended. However, a connecting road system
has also been incorporated, although through Watana and
the Denali Highway and not directly west to the Parks
Highway. This issue is discussed further in Section
3.4.2(b) •
E-3-257
3.4-Mitigation Plan
Transmission corridors traverse a variety of vegetation
types with different biomass characteristics (Tables
E.3.77-79 and E.3.86, Figures E.3.39-40 and E.3.49-52).
Their routing has been determined largely by access and
1 and ownership considerations. Because it shares a
common corridor, the Watana-to-Devil Canyon transmis-
sion route traverses low-biomass vegetation types simi-
lar to those crossed by the adjoining access road.
Clearing of vegetation of any type will be minimal
during transmission corridor construction. Mitigative
clearing techniques specifically designed to minimize-
vegetation removal by transmission corridors are
discussed below.
Impacts of vegetation removal are relatively greater if
the vegetation types removed are 1 ess abundant (have
lower total areal coverage) than other plant communi-
ties in the project area. Vegetation types with low
areal coverage within the Watana and Gold Creek water-
sheds are closed spruce forest, open and closed birch
forest, herbaceous alpine tundra, and wet sedge-grass
tundra (Table E.3.51). Within the 20-mile-wide (32 km)
area surveyed in greater detail along the Susitna River
from the Maclaren River (RM 260) to Gold Creek (RM
136.8), less abundant vegetation types are herbaceous,
closed balsam poplar forest, grassland, open and closed
birch forest, and wet sedge-grass tundra (Table
E.3.52). Herbaceous alpine tundra will not be affected
by the project (McKendrick et al. 1982). The herbac-
eous, balsam poplar, and grassland types occur primar-
ily along the downstream floodplain and tributaries of
the Susitna River (McKendrick et al. 1982) and wi 11
not require direct vegetation removal for facility con-
struction with the exception of 111 acres (45 ha) of
herbaceous floodplain pioneer vegetation to be inun-
dated by the Watana impoundment and 0.7 acres (0.3 ha)
of closed balsam poplar to be cleared for rai 1 road
construction (Tables E.3.83 and E.3.85). However,
these vegetation types will potentially be affected by
regulated flows, as discussed in Section 3.3.1(c). A
balsam poplar stand near Deadman Creek at access mile-
post 37.5 has been avoided by a one-half-mile route
realignment to protect a bald eagle nest in the stand
(Section 4.4, Figure E.3.81).
Low abundance vegetation types which will receive the
greatest cumulative impact from construction of the im-
poundments and dams, access and transmission corridors,
and all ancillary facilities will be closed spruce for-
est, open and closed birch forest, and wet sedge-grass
E-3-258
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3.4-Mitigation Plan
tundra (Tables E..3.80 a.nd E.3.83-86). A total of 252
acres (102 ha) of closed spruce forest will be tra-
versed by the transmission corridors. Based on
1:250,000-scale mapping of the project area (Table
E.3.51), as much as 32 percent of the total coverage of
closed spruce forest in the Watana and Gold Creek
watersheds (i.e., 798 acres or 323 ha) could potential-
ly be cleared during the winter of 1989-1990. However,
the application of selective clearing and other mitiga-
tive techniques involving transmission corridor con-
struction will reduce the actual number of individual
trees removed, as discussed below.
A cumulative total of 3428 acres (1388 ha) of open and
closed birch forest could be affected by construction-
related clearing between 1985 and 2002. Based on the
1:63,360-scale mapping of the 20-mile (32-km) strip
along the Susitna River for which the greatest deta.il
is available {Table E.3.52), 36 percent of the total
9440 acre·s {3822 ha) of this vegetation type could be
removed by construction. About 2250 acres (911 ha) or
24 percent of the tot a 1 coverage will be entire 1 y re-
moved by clearing of the impoundments (Tables
E.3.83-84). The remaining 1178 acres (477 ha) will be
selectively cleared as discussed further below.
The third low-abundance vegetation type to be affected
by construction, wet sedge-grass tundra, will be
crossed by access and transmission corridors (481
acres, 195 ha) (Tables E.3.80 and E.3.85-86) and inun-
dated within the impoundment areas (235 acres, 95 ha)
(Tables E.3.83-84). Borrow Area D (Figure E.3.37) will
potentially remove an additional 20 acres {8 ha) (Table
E.3.83). The siting of all pads, buildings, and other
structural facilities has entirely avoided this vegeta-
tion type. Therefore, a total of 736 acres (298 ha) of
wet sedge-grass tundra will be potentially affected by
construction between 1985 and 2002. This cumulative
impact represents about 9 percent of the tot a 1 8687
acres (3517 ha) present within the 20-mile (32-km)
strip mapped at 1:63,360 (Table E.3.52). Mitigative
measures which will minimize drainage alterations in
this wet veg'etation type are discussed in Section
3.4.2(c).
In summary, siting of pads, buildings, the Watana air-
strip, and other ancillary facilities has minimized
clearing requirements lor low-abundance vegetat1on
types. As residual impact, the impoundments and access
and transmission corridors will remove about 32 percent
E-3-259
3.4 -Mitigation Plan
of closed spruce forest in the Watana and Gal d Creek
watersheds, as well as 36 percent and 9 percent of
birch forest and wet sedge-grass tundra, respectively,
within the 20-mile (32-km) strip mapped at 1:63,360.
Construction-related impacts of vegetation removal can
be minimized further by siting facilities to avoid pro-
ductive wildlife habitat. In this sense, the affected
vegetation has less value, and thus its removal
contributes less to cumulative impact. However, this
option applies only to facilities with flexible siting
requirements. Because the dam and impoundment sites
are fixed, 1 oss of vegetation as a result of their
construction cannot be minimized, rectified, or reduced
over time, but can be offset only through compensation,
as explained later in this section.
Without mitigation, the clearing of vegetation for per-
manent facilities will reduce carrying capacity for
wildlife, as discussed in Sections 4.3 and 4.4.1; miti-
gation plans to offset this loss are presented in Sec-
tion 4.4.2. These plans include the selective siting
of access roads, transmission corridors, borrow areas,
and the Devil Canyon railhead facility to minimize re-
moval or disturbance of wildlife habitat. Siting and
route alterations for this purpose have been made
through the interaction of environmental specialists
with project engineers and are summarized in Figures
E.3.79-82.
Vegetation removal resulting from access road construc-
tion would be minimized most completely by selection of
the shortest alternative route (Access Plan 13--see
Chapter 10, Section 2.3). However, as stated above,
schedule constraints have necessitated selection of the
93-mile (149-km) Plan 18 route, which provides road
access from the Denali Highway and rail access from
Gold Creek. This route incorporates siting and design
features which will m1n1m1ze removal of wildlife
habitat. A major advantage is that moose and brown
bear habitat south of the Susitna River, particularly
near Prairie Creek, Stephan Lake, and the Fog Lakes,
will not be directly affected by vegetation removal and
other construction-related impacts. This avoidance of
productive habitat south of the Susitna River agrees
with and implements recommendations of the ADF&G
(1980, 1982), the Susitna Hydroelectric Steering
Committee (1981), and the USFWS (1982).
E-3-260
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3.4 -Mitigation Plan
As shown in Figure E.3.79, two major realignments have
been made to the 42-mi 1 e (67-km) Denali Highway-to-
Watana segment, progressively moving the route westward
from relatively flat, low terrain (2000-3500-foot
{600-1050 m) elevation) to the lower slopes of
mountainous terrain in the northern portion of the
project area {3500-4000-foot {1050-1200 m) elevation).
These realignments have provided several advantages.
First, potential drainage and siltation impacts
associated with construction in the low, wet terrain to
the east have been avoided. Second, the two earlier
route alternatives joining the Denali Highway near
Snodgrass and Butte Lakes were 1 onger and would have
crossed more streams and wet areas. For example, the
Butte Lake alternative passes within 100 yards {91 m)
of Deadman LaRe for a continuous distance of 2 miles
(3.2 km} and closely transits Deadman Creek along a
5-mile {8-km) stretch. In addition, the earlier
alternatives crossed flat terrain historically within
the range of the Nelchina caribou herd (Section 4.2).
The adjusted route follows the transition zone between
level range and mountainous terrain, leaving the
lowland area uncrossed by any potentially disturbing
structure. Third, the adjusted route now follows
relatively well-drained terrain and soil types which,
for the most part, allow construction using side-borrow
or balanced cut-and-fill techniques, rather than the
bermed construction mode required for roadbeds crossing
wet, poorly drained areas.
As discussed in greater deta·il below, side-borrow and
balanced cut-and-fill techniques provide road sections
which present less of a physical and visual barrier to
passing wildlife such as caribou and moose. Thus,
where vegetation is replaced by a physical structure,
the potential for that structure to block free passage
of big game has been reduced by selective siting which
allows preferred construction modes.
Using side-borrow and ba 1 anced cut-and-fill techniques
also reduces gravel requirements, thereby minimizing
the areal extent of vegetation removal, and confines
gravel extraction to the access corridor itself, thus
consolidating the impact. Similar terrain and soil
considerations have governed routing of the 37-mile
(59-km} Watana-to-Devil Canyon road and the 12-mile
{19-km} railroad extension, which will also rely on
balanced cut-and-fill construction to minimize removal
of wildlife and habitat.
E-3-261
3.4 -Mitigation Plan
In addition to the major realignments described above,
options for smaller route adjustments have been fully
exercised to avoid site-specific habitat loss or direct
disturbance of wildlife. These local modifications and
the features avoided are documented in Figures
E.3.80-82. Red fox den complexes and surrounding habi-
tat (characteristic of well-drained~ sloping terrain)
have been avoided by careful original routing or
changes in a 1 i gnment at MP 28, 32, 34. and 36. At MP
38, the original alignment passed through a balsam
poplar stand containing a bald eagle nest. In
compliance with provisions of the Bald Eagle Protection
Act {16 USC 668-668c), the route has been realigned to
pass 0.5 mile (0.8 km) west of the nest location. As
shown in Figures E.3.80 and E.3.81, additional route
changes have been made to avoid impacts to surrounding
palustrine vegetation, water quality, and resident fish
of Deadman and Tsusena Creeks. These realignments are
discussed from a fisheries standpoint in Section 2.4.
West of the Watana damsite, access routing has been ad-
justed to avoid potential disturbance to the fox den
complex (not shown) at Swimming Bear Lake (MP 18 of the
Watana-to-Devil Canyon route). Beaver concentrations
at MP 34 and 36 in the vicinity of the Devil Canyon
damsite have also been avoided by road realignments, as
shown in Figure E.3.82. Particular attention has been
given to the golden eagle nest on the cliff along the
north side of Devil Canyon at MP 34. 5. The access
route in this vicinity was realigned to avoid the nest
site by 0.5 mile (0.8 km) to the north (Figure
E. 3. 82).
Jack Long Creek, a productive beaver stream, occupies a
swale approximately 1700 feet (515 m) south of the
Devil Canyon construction village and campsite (Figure
E.3.82). This stream and the surrounding wet area are
vulnerable to impacts of vegetation removal associated
with construction of the camp and village, transmission
corridor, and access route. Options to minimize dis-
turbance to Jack Long Creek and resident beaver include
resiting the camp and village, selecting road instead
of rail access from Gold Creek to provide greater flex-
ibility in access routing, realigning the rail route to
the extent feasible, and aligning the transmission
corridor away from the creek.
As explained earlier in this section and shown in Fig-
ure E.3.39, the camp and village are subject to siting
E-3-262
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3.4 -Mitigation Plan
constraints imposed by the occurrence of wet sedge-
grass vegetation type in the area, and have been sited
on locally higher, drier terrain supporting closed
mixed forest. Their locations are considered to be
sufficiently flat and distant from Jack Long Creek to
prevent erosion runoff into the drainage following
vegetation removal.
Selection criteria and rationale for rail access from
Gold Creek are explained in Exhibit E, Chapter 10, Sec-
tion 2.3, and are considered sufficiently favorable to
prevent changing access from Gold Creek to road instead
of rail. Agency recommendations have consistently sup-
ported this position (SHSC 1981, USFWS 1982). There-
fore, the rail alignment has been modified to follow
the hillside south of Jack Long Creek at approximately
the 1600 to 1800 feet (500 to 550 m) contour level,
instead of the original alignment on lower ground along
the north side of the creek (Figure £.3.82). The
modified a 1 i gnment will keep the ra i 1 road extension
away from the active drainage area of Jack Long Creek.
The railhead facility at Devil Canyon will consist of a
poured concrete pad approximately 2500 feet (758 m)
long and 800 feet (242m) wide, accommodating the main
track, two sidings, and areas for equipment,
offloading, and storage. The Jack Long Creek drainage
and a beaver pond near the head of the drainage system
impose difficult constraints on the siting of this
facility. The pad was originally sited on the north
side of the creek between the streambed and the Devil
Canyon campsite. With realignment of the rail
extension to avoid impacts to the drainage, the
railhead facility has also been relocated south of the
creek on relatively flat ground at an elevation of
about 1500 feet (454 m). This siting avoids both Jack
Long Creek and the beaver pond, and removes any
necessity for the.rail extension to cross the drainage
at this point (Figure £.3.82). Crossing of the
drainage to allow access to the camp and construction
areas will be accomplished by construction of a bridge
with minimal vegetation removal. This issue is
discussed further in Section 3.4.2(c) with respect to
potential drainage alteration.
The transmission corridor has been aligned to avoid
Jack Long Creek and is not expected to produce
construction-related impacts on beaver habitat.
Access to the corridor for construction wi 11 be by
temporary bridge across Jack Long Creek from the rai 1
corridor.
E-3-263
3.4 -Mitigation Plan
In summary, potential effects of construction-related
vegetation removal on wildlife habitat have been min-
imized by routing access and transmission corridors as
much as possible away from areas where these structures
would disturb big game and fishery resources. In all
cases, specific locations of nests, dens, and beaver
activity have been entirely avoided by facility siting.
Impacts of vegetation removal during construction have
also been minimized by reducing volume requirements for
borrow extraction. The options chosen to accomp 1 ish
this are use of side-borrow and balanced cut-and-fill
techniques in access road design, and incorporation of
a flexible design speed. As explained above, applica-
tion of construction procedures depends on types of
terrain and soi 1 traversed. Siting of access routes
has therefore avoided 1 ow, wet areas and made maximum
use of well-drained, higher terrain where gravelly
soils are available as construction material. This ap-
proach has the additional advantage of avoiding po-
tential wetlands and waterbodies, thus minimizing
drainage-and siltation-related impacts to aquatic re-
sources.
The section of road from the Denali Highway to the
Watana camp (41.6 miles, 66.6 km) follows terrain and
soil types which wi 11 allow construction using
primarily side-borrow techniques. This approach
minimizes vegetation removal away from the alignment by
confining road construction activities to an
approximately 20-feet (6-m) strip along each side of
the roadbed. A typical cross-section of a road
constructed by side-borrow is shown in Figure E.3.83.
The finished road section using side-borrow
construction is such that the crown of the road is only
2 to 3 feet (less than 1m) above original ground level
compared with 5 to 6 feet (up to 2 m) for a
conventional berm-type, end-dumped section. Thus the
side-borrow approach not only minimizes vegetation
removal and consolidates disturbance, but also produces
less of a visual and physical barrier to passing
wildlife.
In side-borrow construction, the road is developed in
800 to 1000 feet (240 to 300 m) segments. Overburden
is removed, hauled to the previously constructed
segment, and deposited in the previously excavated
borrow trenches. Only at the start of construction is
overburden deposited on undisturbed vegetation, and
then only within the corridor which will be developed
subsequently. As the borrow trenches alongside the
roadbed are excavated, the borrow is used to build the
E-3-264
-
3.4 -Mitigation Plan
road. Upon completion, the removed overburden is
hauled back from its temporary storage location in
borrow trenches of the previously constructed road
segment and used to backfill the newly excavated side
trenches to provide a 4:1 to 6:1 slope which helps to
stabilize and insulate the shoulder (Figure E.3.83).
The overburden is then fertilized and seeded.
In contrast to end-dumping, side-borrow does not re-
quire the excavation of material sites away from the
alignment. As shown in Figure E.3.37, nine borrow
areas have been identified along the Denali Highway-to-
Watana segment as far as MP 32. These wi 11 be exca-
vated only on a contingency basis to support road con-
struction in cases where side-borrow material is not
available in sufficient quantities. In this event, ex-
cavati 6ri required for maximum materia 1 extraction to
develop a given segment of road will average about
8 feet (2.5 m) in depth and remove vegetation over an
area of from 10 to no more than 20 acres (up to 8 ha).
Removed overburden wi 11 be stockpi 1 ed temporari 1 y in
nearby locations selected and prepared on a site-
specific basis to minimize runoff potential (i.e.,
flat, well-drained upland locations not above streams
and with no active or intermittent drainage nearby,
with appropriate berms and/or trenches), then deposited
back in the borrow area and immediately fertilized,
scarified and seeded. Material required to support
construction of the Dena 1 i Hi ghway-to-Watana segment
south of MP 32 wi 11 be obtai ned from damsite borrow
areas D or E (Figures E.3.37 and E.3.40).
The connecting road between Watana and De vi 1 Canyon
crosses primarily low shrub and tundra vegetation types
(Table E.3.85, Figures E.3.39-40 and E.3.43-44) under-
lain by usable soils with bedrock at or near the
surface. This road segment will be constructed by
sidehill cutting emphasizing balanced cut-and-fill to
minimize ancillary material extraction. As shown in
Figure E.3.37, five potential borrow areas have been
identified along the route on a contingency basis in
the event that additional fill is needed to augment
materia 1 obtai ned from s idehill cuts. These borrow
areas, if used, will have excavated dimensions not
exceeding those described above for the Denali Highway-
to-Watana segment.
Balanced cut-and-fill construction generally is fea-
sible only where excessively deep cuts are not required
E-3-265
3.4-Mitigation Plan
to minimize grades. Routing of the Watana-to-Devil
Canyon road has followed gentle-to-moderate slopes
where deep cutting will not be required. However, in
steeper terrain such as approaches to stream crossings
and the high-level Susitna River bridge, requirements
for deep cutting have been greatly reduced by incorpor-
ating a flexible design speed which will allow steeper
grades and shorter-radius horizontal curves than a uni-
form 55 mph design speed would accommodate. In these
cases, design speed will be reduced to no less than 40
mph, minimizing the need for fill material from extran-
eous material sites. Incorporation of design speed
flexibility has also allowed the alterations in align-
ment to avoid biologically sensitive features described
above, as shorter-radius curves were required in some
cases.
In summary, impacts of construction-related vegetation
removal have been minimized by reducing val ume
requirements for borrow extraction. This has been
accomplished by:
• Access alignments which follow well-drained upland
terrain with soils suitable for use as construction
material;
Use of side-borrow and balanced cut-and-fill road and
railroad construction techniques; and
• Incorporation of a flexible road design speed to
avoid the necessity for deep sidehill cuts with ex-
cessive fill requirements.
The di spas a 1 of spoil from canst ruction and borrow ex-
cavations will create a potential for vegetation re-
moval either through direct burial or through clearing
for spoil disposal sites. Spoil will be produced
primarily from the processing of excavated rock and
gravel required for dam construction, concrete
aggregate, and support pads for buildings and temporary
service roads. The locations of proposed excavation
areas are shown in Exhibit E, Chapter 2, Figures
E.2.132-135 and E.2.187-189, and in Figures E.3.37 and
E.3.39-40; borrow areas are described in Chapter 10,
Sections 2.5.1 (Watana) and 2.5.2 (Devil Canyon).
Large vo 1 umes of spoil will be produced between 1986
and 1991. For example. about 60 mcy of material will
be required from borrow areas E and I for the outer
shell of the Watana dam. About 32 percent by volume of
pit-run· materia] from these sites is estimated to be
E-3-266
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3.4 -Mitigation Plan
silt and sand which will be removed by washing and
screening (wet processing). Therefore a total of about
88 mcy will be excavated, producing about 28 mcy of
spoil requiring disposal.
The only cost-effective way to avoid removing vegeta-
tion for disposal of the large volumes of spoil pro-
duced by dam construction will be to deposit the spoil
within the impoundment areas. However, this option
must be limited by the need to prevent fines from being
entrained by surface water flow. Thus 1 ocat ions for
spoil disposal within the impoundment areas must be
carefully selected and clearly designated in areas
which will quietly pond during filling, well away from
turbulent flows associated bed with intake structures.
Approximately 10 mcy of material will be required from
Borrow Area D for construction of the impervious core
of the Watana dam. Wet-processed spoi 1 from Borrow
Area D will be deposited on relatively flat sites
within the impoundment area away from the diversion
tunnel intakes and main intake approach channel
(Exhibit F, Plan F4). Exact locations of spoil
disposal areas within the Watana impoundment will be
determined during detailed engineering design. Prior
to the start of filling in 1991, and while the
cofferdams and diversion tunnels are operative, fines
will be sequestered by temporary construction berms.
However, protection from entrainment during diversion
and filling will be provided by locating spoil disposal
sites away from areas of turbulence or high-velocity
currents, and not solely by berms or other temporary
construction measures.
The approximately 28 mcy of spoil produced by dragline
mining and processing of materia 1 from borrow areas E
and I will be disposed of within the excavation limits.
It is expected that the mined areas .of these sites will
pond at river 1 evel (1420-1440 feet, 430-436 m) prior
to construct'ion of the Devil Canyon dam, and that a
1 arger area pool wi 11 form at reservoir level (1455
feet, 441 m) following Devil Canyon development. The
pool area will depend on act!Jal :excavation limits. A
conceptual drawing of the pool is provided in Figure
E.2.25.
During excavation of borrow areas E and I, spoil will
be deposited temporarily in the vicinity of the gravel
processing plants, generally along the northern peri-
meter of excavation at any given stage in mining. The
fines will be contained by temporary construction berms
or in temporary pits. Permanent deposition wil1 be
E-3-267
3.4 -Mitigation Plan
above the estimated 50-year flood 1 evel of about 1473
feet (442 m). During filling of the Devil Canyon
reservoir, the deposited fines will be covered with
vegetation slash and debris produced during reservoir
clearing. A more detailed description of construction
methods--including spoil disposal, siltation control,
and site rehabilitation--to be employed at borrow areas
E and I will be submitted in March 1983 as part of a
supplement to the Susitna Hydroelectric Project
Feasibility Report.
Borrow Area G will be excavated between 1995 and 2000
as a source of concrete aggregate for construction of
the Devil Canyon dam and ancillary facilities. This
borrow area is a first-level terrace site on the south
side of the Susitna River, occupying the area between
Cheechako Creek and the Devil Canyon damsite. The ter-
race elevation ranges from about 925 to 1175 feet (280
to 356m). Aggregate will be processed on the site and
spoil deposited in the vicinity of the processing
plant, which will change as excavation proceeds.
Excavation spoil from construction of the Devil Canyon
saddl edam will be hauled or transported by conveyor
belt and also deposited in Borrow Area G. Fines will
be sequestered in bermed cells within excavated
portions of the borrow area above the diversion tunnel
intake elevation of 870 feet. Spoil will not be
inundated until blockage of the diversion tunnel at the
start of reservoir filling in 2001. All of Borrow Area
G and spoil deposited therein will be entirely
inundated by the Devil Canyon reservoir and will lie
about 500 feet (151 m) below the surface elevation of
1455 feet (441 m).
Access road construction is not expected to produce
non-usable spoil requiring separate disposal sites.
Geotechnical alignment studies will be conducted during
detailed engineering design to provide data necessary
to avoid ice-rich soils. Road construction will
utilize materials which allow side-borrow and balanced
cut-and-fill techniques which generate no excess
spoil.
In summary, vegetation removal will not be required for
major spoil disposal during construction of the Susitna
Hydroelectric Project. Spoil produced during the
Watana and Devil Canyon developments will be deposited
in the impoundment areas in a manner which will avoid
entrainment during construction or operation, and
entirely inundated. This mitigation measure is in
agreement with a recommendation of the USFWS (1983).
E-3-268
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3.4 -Mitigation Plan
Access road construction is not e.xpected to produce
excess spoil.
Construction of the 42-mile (67 km) transmission
corridor from Watana to the Gold Creek switching
station will occur from 1989 through 1992 (Figures
E.3.37-40 and E.3.81-82}. This corridor will consist
of a right-of-way 300 feet (91 m) in width with two
parallel 1 i nes of towers spaced 115 feet {35 m) apart
from centerline to centerline, and with tower-to-tower
spans of 1200 to 1300 feet (364 to 394 m) (Figure
E.3.85). During this construction, the Anchorage-to-
Fairbanks transmission corridor (including the Willow-
to-Healy intertie) will be widened to accommodate an
additional single-tower right-of-way 190 feet (58 m)
wide. The alignment of the added right-of-way may
depart from the previously established corridor in
locations where constraints of land ownership,
environmental features, or aesthetics are present.
From 1999 through 2001, an 8-mile (13-km) corridor will
be built from the Devil Canyon damsite to Gold Creek
switching station. This additional corridor will con-
sist of two parallel lines of towers adjacent to the
previously constructed Watana-to-Gold Creek
configuration, requiring the right-of-way to be widened
to 510 feet {155 m) to accommodate the towers four
abreast. At that time, the Gold Creek-to-Anchorage
transmission corridor will be widened by 190 feet (58
m) to accommodate an additional line of towers. Thus,
with construction of the Watana and De vi 1 Canyon dams,
two lines of transmission towers will extend from Gold
Creek to Fairbanks, and three lines of towers from Gold
Creek to Anchorage. A more detailed description of the
transmission corridors and their selection is provided
in Chapter 10, Section 2.4.
At the start of Watana development in 1985, a 69 kv
service transmission line will be constructed along the
Denali Highway-to-Watana access road. This line will
be constructed using conventional utility poles and re-
moved in 1994 or 1995 upon commissioning of the Watana
facility. Clearing of vegetation is not anticipated
for construction or maintenance of the temporary ser-
vice line.
The areal extents of vegetation types potentially to be
affected by the Susitna project transmission corridors
are summarized in Tables E.3.79, 80, and 86. It should
be noted that these areas may change to a limited ex-
tent as alignments are refined during detailed engi-
E-3-269
3.4 -Mitigation Plan
neering design and construction planning. It is fur-
ther emphasized that these quantities do not indicate
areas of vegetation which will actually be removed by
transmission corridor construction and maintenance. In
fact, as stated i~ Sections 3.3.4(a) and 3.3.6{a)(iv),
the 18,040 acres (7300 ha) required for transmission
corridor rights-of-way will be cleared only to a lim-
ited extent, as explained in the following discussion.
The Power Authority has developed a mitigative approach
for construction and maintenance of transmission cor-
ridors in Alaska. Much of the following description is
presented in the Power Authority 1 S environmental as-
sessment report for the Anchorage-Fairbanks transmi s-
sion intertie (Commonwealth Assoc. 1982), an integral
part of the Su sitna transmission system. However,
clearing limits apply specifically to the Susitna
project.
Surveying will be required a 1 ong rights-of -way to 1 o-
cate centerlines and transmission tower positions. The
survey work will ·involve limited cutting of trees and
shrub vegetation for line-of-sight staking and distance
measuring. No roads will be established during survey-
; ng.
Clearing of rights-of-way will be done selectively,
with typical clearing limits as shown in Figure E.3.85.
The illustrated clearing 1 imits would apply to guyed
X-type towers up to 85 feet (26 m) tall on level ter-
rain. Detailed criteria for different types and
heights of towers and for differing terrain wi11 be
prepared during detailed engineering design. In gen-
eral. cleaning will be limited as follows:
-The maximum height of vegetation on the inside buffer
edge will be 10 feet {3m).
-The maximum height of vegetation on the outside buf-
fer edge will be 60 feet (18m).
- A corridor of vegetation not exceeding 10 feet (3 m)
in height will be maintained between the transmission
lines except at tower sites.
-At tower sites, transverse strips 30 feet (9 m) in
width will be cut through to adjacent lines.
-Tower-to-tower span will be 1200 to 1300 feet {364 to
394 m).
E-3-270
17"" '
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I
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3.4 -Mitigation Plan
-The area under the lines, including 5 feet (1.5 rn)
beyond the outside phases, will be clear cut to
within 6 inches (15 em) of ground level, with growth
under 24 inches {62 em) left in place.
-At tower sites and in areas occupied by access trails
(described below) or temporary construction facili-
ties, all vegetation may be cut. Grubbing of stumps
and stripping of the organic surface 1 ayer wi 11 be
required for tower erection in some cases.
The above clearing limits will apply only to vegetation
within rights-of-way. Outside rights-of-way, there
will be additional, 1 imited clearing to remove danger
trees and to allow access (described below). Danger
tre.es are trees located outside the clearing 1 imits
which are of sufficient height to come in contact with
towers, guys, or lines if the tree were to fall. Such
trees will be located, flagged, and felled by hand
tools or portable power saws, then hauled into the
right-of-way for disposal. Special permission will be
requested of landowners or land management agencies to
allow removal of danger trees.
Clearing of vegetation will be done by Hydro-axe,
v.ehicle-mounted shears, and hand-held power saws. Add-
itional equipment, including bulldozers, will be used
to stock pi 1 e slash and debris within rights-of-way
prior to burning. The stockpiled vegetation will be
allowed to dry through the summer immediately following
clearing and control-burned under constant supervision
at the end of the summer. B11rning· wHl nelp to reduce
the potential for spread of spruce budworm and other
insects.
The Power Authority intends that ground access be used
for construction and maintenance of the transmission
corridors. The use of he 1 icopters for these purposes
has been carefully con~idered, because it is recognized
that this option would reduce requirements for access-
related clearing of vegetatiion and thus serve a signif-
icant mitigative function. However, the limitations of
helicopter use include high cost, limited load-carrying
capacity, weather-related restrictions, daylight use
only (particularly during winter months), and· unaccept-
able safety risks in the vicinity of high-voltage lines
and guyed towers.
Construction and maintenance contractors will be re-
qui re.d to prepare access plans acceptable to the Power
E-3--"2:71
3.4 -Mitigation Plan
Authority and controlling agencies or landowners. Min-
imizing requirements for clearing of vegetation will be
an important criterion for the evaluation and approval
of these plans. Basic elements of access planning will
include:
-Stipulation that existing roads must be used to the
nearest point of transmission corridor access;
-Permission for contractors to build construction
trails from the nearest points on existing roads to
the rights-of-way;
-Stipulation that construction trails be established
only after thorough onsite assessment of alternative
routes and procedures to ensure minimal environmental
disturbance, including avoidance wherever feasible of
dense vegetation, stream crossings, wetland and
floodplain areas (identified with the concurrence of
the COE and USFWS), and extensive switchbacks on
steep, erosion-prone terrain; and
-Use of minimum standard trails from tower to tower
along the inside cleared portions of the rights-of-
way.
For construction of the Watana-to-Gold Creek transmis-
sion corridor during 1989-1992, the connecting road
between the two dams ites wi 11 be built as plan ned and
maintained year-round. Construction trails from the
main access road to the rights-of-way wi 11 be cleared
along approved alignments. Because use of the con-
struction trails will be limited to flat-tread or
balloon-tire vehi~les, fill placement or removal of the
organic 1 aye r will not be requ i red. From the south
bank of the Susitna River to Gold Creek switching sta-
tion, the railroad extension right-of-way will be de-
veloped as a minimum-standard (approximately 20 feet or
6 m wide) road to support transmission corridor
construction. Equipment access to Gold Creek switching
station will be provided along the intertie right-of-
way.
It is anticipated that maintenance-related clearing of
transmission corridor rights-of-way will be necessary
approximately every 10 years. During ,intervals between
periodic clearing, vegetation within the rights-of-way
will be allowed to grow without disturbance, except for
the occasional removal of danger trees as required, or
E-3-272
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3.4 -Mitigation Plan
localized clearing associated with tower and line main-
tenance or repair. It is the established policy of the
Power Authority that herbicides are not used for any
aspect of transmission corridor construction or main-
tenance.
The selective clearing of transmission rights-of-way
wi 11 result in enhanced browse production associated
with sprouting and succession. Clearing will thus aug-
ment other measures to compensate for proj ect-re 1 a ted
loss of browse, as discussed in Section 4.4.2{b). Fur-
ther benefit will be derived by goshawks, sharp-shinned
hawks, and other raptors and owls which will hunt along
the rights-of-way as discussed in Section 4.3.4(c).
These benefits must be weighed against the potentially
adverse effect of increased pub 1 i c access which
portions of the rights-of-way may provide. The issue
of increased access is discussed in Sections
3.3.1{b)(v) and 4.3.3, and below in Section 3.4.2(b).
On-ground evaluations will be made during detailed
engineering design and construction planning regarding
appropriate management procedures for specific portions
of the transmission corridors (e.g., the extent of
clearing, maintenance requirements, and potential
seeding of areas disturbed during construction). These
site assessments will be conducted in coordination with
representatives of the USFWS, the ADF&G, and the Alaska
Plant Materials Center, as recommended by the USFWS
(1983).
Access to transmission corridors has been coordinated
closely with access along roads, the railroad
extension, and already existing adjacent transmission
corridors, as recommended by the USFWS (1983), the
Susitna Hydroelectric Steering Committee (1981) and the
EPA (1981). Policies on public access during and after
construction and along the length of the corridors will
be consistent with management policies of agencies and
landowners with jurisdiction over the properties
traversed by the corridors.
E-3-273
In summary, the direct removal of vegetation as a
result of transmission corridor construction and
maintenance will be minimized through the application
of selective clearing techniques which will remove only
vegetation that might impede access, construction, or
maintenance of the transmission system. ·Vegetation
removal will be minimized further by constraints
imposed on the routing of access trails to the
rights-of-way, and especially by alignment of the
Watana-to-Devil Canyon access road and transmission
right-of-way together along a common corridor.
Herbicides will not be used. Selective clearing
repeated approximately every 10 years will enhance
browse and hunting habitat for moose and certain
raptors, respectively,·by maintaining cleared portions
of the rights-of-way in early successional stages.
The Power Authority will apply all of the minimization
measures described above to mitigate impacts of
vegetation removal during construction and operation of
the Susitna Hydroelectric Project. These measures will
begin with potential FERC licensing and scheduled
construction startup in 1985, and continue through the
50-year license period to 2035.
Minimization of vegetation removal will affect a sig-
nificant area and make an important contribution toward
mitigating the cumu~ative impact of the Susitna project
on vegetation. The precise areal extent of vegetation
cover saved from removal cannot be quantified
defensibly until detailed engineering designs and
construction plans are formulated, and even then, only
on a provisional basis. However, some examples can be
provided as follows.
Of the approximately 66,679 acres (26,995 ha) potenti-
ally subject to vegetation removal on a cumulative·
basis, about 30 percent, or 19,236 acres (7788 ha),
will allow application of the mitigation measures de-
serf bed above. Approximately 46 percent of th-e total
area covered by transmission corridors (7444 acres
[2978 ha] of the total 16,182 acres [6473 ha]) will be
left uncleared or partly cleared. In addition, use of
side-borrow and balanced cut-and-fill techniques for
construction of the access roads and railroad extension
will protect up to 280 acres ( 112 ha) of vegetated
a rea.
E-3-274
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3.4 -Mitigation Plan
(in
Using the two examples cited above, measures to
minimize vegetation remova 1 will conserve about 7724
acres {3127 ha), or up to about 40 percent of the land
area in question. If spoil produced by processing of
borrow material needed for dam construction were
deposited outside borrow area excavation limits or
outside the impoundment areas, additional vegetation
would be removed or burned. For example, deposition of
spoil from borrow areas E and I to a depth of 3 feet
(.09 m) would cover 5782 acres (2341 ha).
Although the quantities in these examples must be con-
sidered hypothetical at the present stage of design, it
is nevertheless evident that measures to minimize vege-
tation removal will have an appreciable mitigative ef-
fect on the cumulative impact of project construction
and operation.
Rectification
Certain ancillary project facilities will be required
on a temporary basis during construction and vacated
when construction has been completed. Vegetation
removal resulting from development . and use of these
facilities can be partially rectified by dismantling
the structures, rehabilitating the underlying soils,
and preparing the soils to allow reestablishment of
vegetation. These options will be followed to rectify
effects of vegetation removal during construction of
the Watana and Devil Canyon dams. ·
Lands associated with the following temporary
fa·cilities will be rehabilitated ·in accordance with the
schedules shown:
E-3-275
3.4 -Mitigation Plan
WATANA
Facility &
Vegetation Action Year Area
(acres)
Construction Camp Start Canst. 1985 78
-Birch Shrub Complete Canst. 1986 78
-Mixed Low Shrub Dismantle & Reclaim 1994 78
Dismantle & Reclaim 1995 78
Village Start Canst. 1986 86
-Birch Shrub Complete Canst. 1987 87
-Mixed Low Shrub Dismantle & Reclaim 1994 86
Construction Roads Start Canst. 1985 120
-Closed Birch
Forest Continue Con st. 1986 120
Closed Mixed
Forest Complete Con st. 1987 60
-Open Mixed
Forest Grade & Reclaim 1994 150
-Closed Tall
Shrub Grade & Reclaim 1995 150
-Mixed Low
Shrub
Contractor Work
Areas Start Const. 1985 190 r:--
-Closed Birch
Forest Continue Const. 1986 360
-Closed Mixed
Forest Complete Con st. 1987 190
-Open Mixed
Forest Dismantle & Clear 1994 740 ~--Closed Tall
Shrub Grade & Reclaim 1995 370
-Mixed Low
Shrub Grade & Reclaim 1996 370
E-3-276
E-3-277
3.4-Mitigation Plan
DEVIL CANYON {CONT.)
Facility &
Vegetation
Contractor
Work Areas -Open Black
Spruce Forest -Closed Birch
Forest
-Open Mixed
Forest
-Closed Mixed
Forest
Borrow Area K
-Open Black
Spruce Forest
-Closed Mixed
Forest
-Closed Tall
Shrub
-Lake
Action Year
Start Canst. 1994
Continue Con st. 1995
Continue Canst. 1996
Comp 1 ete Con st. 1997
Dismantle & Clear 2002
Grade & Reclaim 2003
Excavate 1995
Excavate & Reclaim 1996
Excavate & Reclaim 1997
Excavate & Reclaim 1998
Reclaim 1999
TOTAL REHABILITATED AREAS--
-Watana 1986-1996
-De vi 1 Canyon 1996-2003
-Total 1986-2003
Area
(acres)
150
150
150
30
480
480
100
100 & 100
100 & 100
65 & 100
65
2079
1130
3209
Rehabilitation of temporary faci 1 ity sites wi 11 only
partially rectify the vegetation loss resulting from
their construction. Provided soils are restored, plant
succession will proceed at various unquantifiable rates
depending on slope, aspect, elevation, soil types,
moisture and drainage conditions, and other factors.
Without restoration of mineral and organic soils,
recovery of forest and shrubl and within the project
area would require 150 years at the very minimum
(McKendrick 1982 personnel communication. Therefore it
may be assumed that some semblance of the original
pattern of lost vegetation will be restored within 150
years on 1 ands prepared for rehabilitation, but
predictions of how plant succession will proceed on
these lands over time would be difficult to justify.
E-3-278
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3.4 -Mitigation Plan
Because rehabilitation procedures for disturbed lands
in Alaska are best developed on a site-specific basis
(Brown et al. 1978), preparation of a comprehensive re-
storation "'j)Tan for the Susitna project has been desig-
nated as a task for the detailed engineering design
phase. An individual restoration plan will be devel-
oped for each area to be rehabilitated. The individual
plans will incorporate tl:le following information for
use by rehabilitation contractors and monitors:
-Plan view (drawing) of area to be rehabilitated, with
limits clearly delineated along with overburden
stockpile locations and areas of special concern
(e.g., erosion, slumping, oil saturation from equip-
ment maintenance shops, etc.);
-Aerial photographs of the area shown in the plan
view, to serve as a photo base for the following
overlays;
Overlays of original vegetation and soil types and
appropriate revegetation classes (Alaska Rural
Development Council 1977);
Overlay of areas requiring special treatment (e.g.,
seeding for erosion control, waterbars, extra top-
soil, extra fertilizer application, etc.);
Specific locations for the stockpiling of organic
overburden, with special protective measures against
drying, wind erosion, and runoff;
-Specific depths and procedures for ripping and scari-
fication during soil preparation;
-Specific quantities and types of fertilizers to be
applied; and
-Specific revegetation mixtures to be used for
seeding, with application rates (lbs/acre) and
methods (drilling or hand broadca~ting).
In general, the following procedural overview gives an
indication of the approach which will be used for site
rehabilitation, based on experience from other projects
i nvol v·i ng non-arctic interior regions of Alaska (for
example, see Pamplil'l 1979). However, specific
restoration plans will provide much greater detail, as
described above.
E-3-279
3.4 -Mitigation Plan
The 1 and surface of disturbed areas wi 11 be ripped
prior to application of topsoil, then graded to contour
and evenly covered with organic overburden and topsoil
previously stockpiled for this purpose. Fertilizer
high in phosphorus (e.g., 10-20-10 or 8-32-16, N-P-K)
will be applied at a rate sufficient to supply 85 to
110 kg of nitrogen per hectare.
Following the spreading of organic overburden, topsoil,
and fertilizer, the site surface will be scarified to a
depth of 12 inches (40 em) using a rake towed by a
mini -Rolli gon type vehicle. This procedure wi 11 mix
the organics with the underlying mineral soil, aerate
the mixture, and 1 ightly compact the surface. During
the second and third growing seasons, followup applica-
tions of fertilizer will be made at one half to
one third the original rates.
Where erosion potential or aesthetic considerations can
be demonstrated not to be involved, site rehabilitation
will emphasize application of organics and nutrients
and minimize seeding. The USFWS (1983) concurs with
this approach, which will encourage the reinvasion of
native species from the surrounding parent population.
For lightly disturbed sites with intact topsoil,
fertilization alone should be sufficient to facilitate
revegetation.
Sites with high erosion or visual impact potential will
be fertilized and seeded with fast-growing native
grasses appropriate to the climate and geography of the
Susitna Basin. To minimize erosion, all sites will be
rehabilitated by the first growing season following re-
moval of structures and equipment. Sufficient
quantities of seeds for sites requiring revegetation
will be stockpiled, and regrowth potentials of
available native strains will be tested prior to
project abandonment of distrubed sites. Choice of
plants for site rehabilitation will be made after
consultation with federal and state natural resource
agencies. This approach has been recommended by the
USFWS (1983).
In summary, recti fi cation wi 11 restore vegetation to
approximately 3209 acres (1299 ha) temporarily lost to
ancillary facilities. This represents about 5 percent
of the cumulative total land area affected by direct
loss of vegetation during project construction and op-
eration (68,537 acres, 27,339 ha).
E-3-280
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3.4 -Mitigation Plan
( i i i )
Rectification will only be partial because of the long
periods (up to 150 years) required for plant succession
to preexisting conditions. Individual restoration
plans will stipulate detailed procedures to facilitate
revegetation on specific sites. Development of these
plans is a designated task of the detailed engineering
design phase of the project.
Reduction
Options for the reduction of direct vegetation removal
over time involve monitoring project facilities and
activities to ensure the most effective use of
rehabilitation measures. During project construction
and operation, the following three tasks will be
performed on a continuing basis:
-Monitoring progress of site rehabilitation to ident-
ify locations requiring repeated or altered applica-
tion of fertilizer and/or seed;
Systematically identifying and rehabilitating areas
where construction activities have ceased and are no
longer required; and
-Coordinating rehabilitation efforts with closure and
removal of service or temporary access roads no
longer required.
These measures will be included in the comprehensive
restoration plan described above in Section
3.4.2{a)(ii) and, in fact, will help to focus and
implement that plan.
In the construction zone of a large project, disturbed
areas partially or wholly without vegetation develop
with expansion of the infrastructure of temporary
roads, residential quarters, storage yards, equipment
maintenance shops, and other ancillary facilities.
Although areal extents have been quantified with
respect to camps, service roads, contractor work areas,
borrow sites, and other facilities, these
quantifications can only estimate the actual extent of
vegetation removal, because zones of activity will
surround these sites. Foot traffic and the movement of
vehicles and equipment wi 11 tend to enlarge areas of
disturbance around centers of activity, despite the
consolidation measures described in Section
3.4.2{a)(iii).
E-3-281
3.4 -Mitigation Plan
One objective of monitoring is to maintain awareness of
disturbed areas as they enlarge or as activities
diminish, so that rehabilitation can begin as early as
feasible. Monitoring of vegetation removal during
construction will provide for the application of
rehabilitation measures in locations other than or
adjacent to the areas specifically targeted in the
individual restoration plans, and on an as-needed basis
throughout the construction period. Monitoring of
vegetation loss will also be conducted during
pre-construction field activities and throughout the
license period to detect later disturbances quring
operation and maintenance.
The monitoring program described above wi 11 be a com-
ponent of the project-wide monitoring plan to be estab-
lished formally during the detailed engineering design
and construction planning phase of the project (Section
1. 3).
(iv) Compensation
By its very nature, a large hydroelectric development
such as the Susitna project will permanently remove a
considerable area of vegetation dedicated to the dam-
sites, impoundment areas, access routes, and permanent
buildings. For the Susitna project, the cumulative
area 1 ost in this way wi 11 total about 45,581 acres
{18,454 ha), with 44,292 acres (17,932 ha) covered by
the impoundments. Actual acreages of vegetation types
which will be removed were discussed previously and
quantified in Tables E.3.83 and E.3.84.
From the preceding options analysis, it is evident that
measures for minimization, rectification, and reduction
of vegetation 1 ass wi 11 apply, at most, to about 30
percent {19,236 acres, 7788 ha) of the total area of
vegetation which will be removed by the project. Loss
of the remaining 70 percent can be mitigated only
through compensation.
Two compensation options have been considered to miti-
gate direct loss of vegetation resulting from project
constuction and subsequent operation:
-Acquiring lands with areal coverages of vegetation
types equivalent to those lost, and protecting the
lands from future development; and
E-3-282
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3.4 -Mitigation Plan
-Prioritizing lost vegetation types relative to value
as wildlife habitat, and then selectively altering
vegetation on acquired lands to replace or exceed
lost areal coverages of the high-priority vegetation
types.
The second option described above has been se 1 ected
because habitat enhancement measurs that alter
vegetation will allow compensation for loss of
high-priority vegetation types while requiring
relatively small areas of replacement land.
As indicated in the wildlife impact discussion (Section
4.3), impacts to moose, brown bear, and black bear
through habitat loss and alteration have received high
priority by project planners. Compensation for loss of
vegetation types important to these species will there-
fore be implemented through habitat enhancement mea-
sures on replacement lands in the middle basin and
downstream from Gold Creek. A detailed description of
this program is provided in Mitigation Plan 6, Section
4.4.2(b). Costs and schedules for the program are pre-
sented in Section 4.4.3.
In conjunction with the ADF&G, the USFWS, and the
University of Alaska, the Power Authority is currently
developing a habitat-based model for moose carrying
capacity based on moose bioenergetic requirements and
browse nutritional value. This program is described as
Nitigation Plan 7 in Section 4.4.2(b) and explained
further in Appendix 3.H. Vegetation studies now in
progress are providing data to support the modeling
program, as described below.
Inventories to quantify physical and nutritional char-
acteristics of moose browse vegetation were conducted
in the project area during the summer of 1982, with
data analysis continuing through early 1983. A plant
phenology study focusing on spring green-up of riparian
vegetation along the Susitna River floodplain in the
middle basin also was conducted in 1982. Early green-
up of riparian vegetation may be an important nutri-
tional source for moose and bears, especially following
severe winters. Third,, species distribution, abun-
dance, and percent cover of vegetation within a desig-
nated 6400-acre controlled burn area on Bureau of Land
M-anagement (BLM) 1 and in the Alphabet Hills (east of
the project area) were quantified in 1982. This
program is being conducted in cooperation with the
E-3-283
3.4 -Mitigation Plan
'Institute of Northern Forestry of the National Forest
Service, the ADF&G, and BLM. As described further in
Mitigation Plan 6, Section 4.4.2(b), controlled burning
is scheduled for August 1983, provided suitable weather
conditions occur. Followup studies characterizing
post-burn plant succession will be conducted in the
future to help assess the suitabi 1 ity of controlled
burning as a method for browse enhancement. It is
likely that burning woodland conifer forest will
produce a herbaceous or shrub stage (Foote 1979)
characterized by rapid nutrient turnover, high
productivity, and relatively high decomposition rates
(Viereck and Schandelmeier 1980). The resulting low
shrub stands will provide approximately a three-fold
increase in browse biomass (Table E.3.92, Figure
E.3.117).
Mapping of moose browse vegetation within the central
portion of the middle basin is currently planned. This
program, described in Section 3.2.2(a), will provide a
means for detailed quantification of browse loss inside
and browse availability outside direct impact areas,
and facilitate application of the moose modeling
program to specific features of the project area.
Integrating the mapping and modeling efforts will allow
more accurate quantification of carrying capacity loss
resulting from the project and will also provide a
means for quantifying replacement land requirements.
The identification of replacement lands for habitat en-
hancement will place highest priority on state and fed-
eral lands which can be acquired at minimal or no cost.
Alaska Department of Natural Resources (ADNR) statutes
(Title 38) set forth provisions for exchanges of state-
owned lands on an equal-value basis following
appraisal. Because state-owned lands supporting black
spruce vegetation types with high enhancement potential
are readily available in the project vicinity, it is
anticipated that exchanges of state lands with ADNR
review and concurrence may provide an avenue for
acquisition of replacement lands.
A second avenue for replacement land acquisition is
provided by Section 907 of the Alaska National Interest
Lands Conservation Act of 1980 (Pub 1 i c Law 96-487).
This provision establishes the Alaska Land Bank
Program, whereby tax ince.ntives and other benefits are
E-3-284
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3.4 -Mi ti gati on Plan
(b)
afforded private landowners who make lands available
for management of fish and wildlife in accordance with
policies of state or federal agencies.
In summary, compensation for permanent vegetation loss
wi 11 be implemented through the acquisition of replace-
ment 1 ands to be managed for browse habitat enhance-
ment. Vegetation studies and mapping are being con-
ducted to support habitat-based modeling of moose
carrying capacity. Modeling results will in turn be
used to quantify project-related loss of carrying ca-
pacity and requirements for rep 1 acement 1 and acqui si-
tion. Costs and schedules for elements of these pro-
grams are summarized in Sections 3.4.4 and 4.4.3, and
in Tables. E.3.177 and 178.
Indirect Loss of Vegetation
Vegetation loss will result from slope instability effects
during and after filling of the impoundment areas (Sections
3.3.1, 3.3.2, and '3·.3.6(b) ). As reservoir soils become sat-
urated and slopes settle to new angles of repose, slumping
and landslides wi 11 occur above and below surface levels.
Erosion and slumping wi 11 result from melting of permafrost,
particularly along the south side of the Watana impoundment
where deep permafrost occurs (Section 3.3.1[b][ii]). These
effects will be intensified in the Watana reservoir by the
yearly periodic freezing, thawing, saturation, and dessi ca-
tion of soi 1 s within the 90-foot (27-m) drawdown zone, by
hydraulic erosion, and by ice formation. Although precise
areal extents and elevation ranges of these effects cannot
be reliably quantified in advance, the following areas will
be susceptible to vegetation loss (Duncan 1983 personal com-
munication).
-The 10-mi le (16-km) reach from the headwaters of the
Watana reservoir (RM 243) to the Oshetna River-Goose Creek
area (RM 233), where cliffs of frozen silts and clays
occur. Predominant vegetation types bordering the i m-
poundment area in this reach are woodland black spruce and
birch shrub (~gure E.3.65).
-The 49-mi le (78-km) reach along the south side of the
Watana reservoir from the Oshetna River-Vee Canyon area
(RM 233-225) to the Watana damsi te (RM 184). This reach
is underlain by 200-to 300-foot deep (60-to 90-m) dis-
continuous permafrost. Predominant vegetation along the
reservoir margin is woodland and open black spruce and low
shrub types (Figures E.3.65-61).
E-3-285
3.4-Mitigation Plan
The 10-mi le (16-km) reach along the north side of the
Watana reservoir between the Watana Creek area (RM 194)
and the Wat ana damsi te (RM 184). This reach is
characterized by unconsolidated glacial outwash, much of
it in the 9-foot (27-m) drawdown zone. Predominant
vegetation types types along the northern reservoir margin
in this reach are woodland and open b 1 ack spruce, birch
shrub, and mixed low shrub (Figures E.3.62-61).
-An old landslide area on the south side of the Devi 1 Can-
yon impoundment at RM 175, about 2 miles (3.2 km) down-
stream from the mouth of Fog Creek (RM 177), and 9 miles
(14.4 km) downstream from the Watana damsite (RM 194-184).
Aerial photographs show this location as forested; and
Figures E.3.61 and 60 indicate that woodland and open
black spruce, open white spruce, and open mixed forest are
the predominant vegetation types.
It is evident that vegetation loss from slope instability,
erosion, and blowdown along the reservoir margins wi 11
produce a cumulative impact in addition to the direct losses
described in Section 3.4.2(a). However, the precise
vegetation types, locations, areal extents, and elevation
ranges which wi 11 be affected by these indirect losses
cannot be reliably quantified in advance. ~/i thout altering
fixed characteristics of the dams and reservoirs, there is
no way to avoid, minimize, rectify, or reduce these impacts.
Loss of low shrub vegetation, important for browse and berry
production, wi 11 be compensated for by the land acquisition
and habitat enhancement programs described in Sections
3.4.2(a)(iv), 4.4.2(b), and 4.4.3.
Additional indirect losses of vegetation will result from
increased human activity within the project area during con-
struction and operation (Sections 3.3.l(b)(v), 3.3.3(a) and
(b), 3.3.4(a) and (b), and 3.3.6(b). Nonessential distur-
bances to vegetation and soils by construction workers can-
not be avoided entirely, but substantial minimization will
be possible through consolidation of facilities and careful
planning of traffic patterns and service roads (Section
3.4.2( a) (i)). Particular attention wi 11 be given to infra-
structure 1 ayout during detailed engineering design and con-
struction planning, including design participation and
review by project environment a 1 speci a 1 i st s.
Thoughtful planning and implementation of an environmental
briefings program requiring the participation of all field
personnel wi 11 make an important contribution towards mini-
mi~ng unnecessary disturbances to soi 1 and vegetation dur-
ing project construction and operation (Appendix 3.B).
E-3-286
-
-
-
-
-
3.4 -Mi ti gati on Plan
Recti fi cation and reduction of vegetation losses, resulting
from activities of construction workers, wi 11 be
accomplished through the rehabilitation and monitoring
programs described in Sections 3.4.2(a)(ii) and (iii).
Increased human activity on public lands surrounding the
project (discussed also in Exhibit E, Chapter 5 -Socio-
economics .. and Chapter 7 -Recreation) could be greatly
diminished by fencing and gating access roads and transmi s-
si on corridors. However, even with these measures, access
would sti 11 be avai 1 able by off-road vehicle (ORV) or all-
terrain vehicle (ATV) from the Parks and Denali Highways and
through the use of small aircraft. Moreover, fencing along
the lengths of access routes and transmission corridors
would block free passage of big game.
During construction of the Watana and Devi 1 Canyon projects
(1985-2002), public access along the Denali Highway-to--
Watana road wi'll be restricted by use of a locked gate
supervised by security guards. Public use of the Gold
Creek-to-Devi 1 Canyon railroad extension wi 11 not be avai 1-
able. These measures will largely avoid increased impacts
to vegetation resulting from recreational users and others
attracted by the project during construction. It should
again be noted, however, that restricting access along the
Denali Hi ghway-to-Watana road wi 11 not necessarily deter or
diminish the existing pattern of access by ORV and ATV from
the Denali Highway, Parks Highway, and Gold Creek onto
public and private lands surrounding the project.
Vegetation loss and soi 1 damage from public access-related
vehicle use wi 11 occur following construction and throughout
the license period (2003-2035) and may inten~fy over time
as population growth and recreational and hunting pressures
increase (see Exhibit E, Chapter 7-Recreation). ORV and
ATV use already is occurring on lands surrounding the proj-
ect and has resulted ·in obvious soi 1 damage and vegetation
loss, as shown in Exhibit E, Chapter 8-Aesthetics, Photos
8.0.5 and 8.0.6.
Increased pub 1 i c access as an indirect consequence of the
project cannot be entirely avoided by the Power Authority
because access to lands surrounding the project is available
through ORV, ATV, and aircraft use, as noted above. The
project access route does, however, avoid areas south of the
Susitna River (Stephan Lake, Prairie Creek, Fog Lakes, as
well as the Indian River area)-which are valuable as wild-
life habitat in keeping with recommendations of the Susitna
Hydroelectric Steering Committee (1981).
E-3-287
3.4 -Mitigation Plan
Options to minimize access-related impacts during the
postconstructi on period include gating on the Denali
Hi ghway-toWatana road to restrict access, use of signs to
deter vehicle departures from the road, special regulatory
designation of the access route to discourage ORV and ATV
use, and consolidation of access-related activities through
design of the project recreation plan.
Policies governing public access to the project area during
the postconstruction years of the license period are
currently under consideration. Such policies will require
agreement among the 1 and and resource management agencies
and private landowners with jurisdiction over lands
surrounding the project. Access-related measures of the
Power Authority wi 11 conform with those policies.
A variety of regulatory options are available for reducing
human activity on public 1 ands in the project area. For
example, the ADF&G (1983) has noted that me'asures may be
taken by the Boards of Game and Fisheries and by the
Commissioner of Fish and Game to relieve hunting and fishing
pressures (see Section 4. 4.l[b]). These options inc 1 ude
entirely closing an area to hunting and fishing or creating
a special use area where motorized vehicles are prohibited
from hunting. Because hunting and fishing are the primary
reasons for use of motorized vehicles within the project
area, such measures could substantially change user
patterns.
Signs may be used to deter road users from driving their
vehicles off the access road onto surrounding terrain, pos-
sibly in conjunction with special regulatory designation.
For example, the Denali Highway is under review by the BLM
for inclusion in the National Scenic Highway System (Ward
and Wr abetz 1982 personal communication). The project
access route may also be eligible for this designation,
which would entail restrictions on off-road vehicle use and
other potentially disturbing activities i ni ti ated from the
access road. However, this measure would also attract
people to the project area.
The Susitna Hydroelectric Project Recreation Plan is pre-
sented in Ex hi bit E, Section 7. A major objective of the
Recreation Plan is to est ab li sh patterns of public access
that will minimize and localize access-related impacts
through the use of trai 1 s and designated camping area. The
Recreation Plan is consistent with fish and wildlife habitat
protection priorities established for the project. In addi-
ti on, the phased design of the Recreation Plan wi 11 ensure
E-3-288
~--~,,
I~
-
3.4-Mitigation Plan
(c)
that implementation will be gradual and based on monitoring
of fish, vegetation, and wildlife impacts as well as
recreational user needs. Implementation of each phase wi 11
be subject to interagency review and concurrence.
In summary, vegetation loss resulting from i nstabi li ty along
the margins of the impoundment areas and from increased pub-
lic access to lands surrounding the project will produce a
cumulative impact augmenting the impact of direct construc-
tion-related vegetation removal. Loss of shrubland browse
species Wi 11 be compensated for by acqui si ti on of replace-
ment lands and habitat enhancement measures, as described in
Sections 3.4.2(a)(iv) and 4.4.2(b). Vegetation loss result-
; ng from increased public access wi 11 be minimized by con-
fining access routes to areas north of the Susi tna River,
use of signs and possibly of special regulatory designation
to discourage ORV and ATV use, and by phased implementation
of the project Recreation Plan with interagency review and
concurrence. In addition, a variety of regulatory options
are av ai lab 1 e to resource management agencies to limit
access on public lands under their jurisdiction.
Alteration of Vegetation Types
Alteration of vegetation types wi 11 be caused by plant suc-
cession, changes in drainage patterns, regulated downstream
flows, and fire. Plant successional changes wi 11 occur
along the margins of the impoundment areas as a result of
the slope instability processes described in Section
3.4.2(b). Because such changes cannot be quantitatively
predicted and because they wi 11 involve an increase in pro-
ductive early-successional stages of value as browse or for-
age, special mitigative measures are not planned.
Potential changes in surface drainage patterns are of
greatest importance where wetland areas are involved. Under
Army Corps of Engineers regulations promulgated by Sections
301 and 404 of the Clean Water Act (33 USC 1344), wetlands
are defined as 11 those areas that are inundated or saturated.
by surface or ground water at a frequency and duration to
support, and that under normal circumstances do support, a
prevalence of vegetation typically adapted for life in
saturated soi 1 conditions" (33 CFR 323.2[c]).
As explained in Section 3.2.3, potential wetlands of the
impoundment borrow areas and of the access corridors were
mapped using the system of Cowardin et al. (1974), as adop-
ted by the USFWS (1980). Further mapping is being i ni ti ated
at a scale of 1:250,000 and will delineate wetland vegeta-
E-3-289
3.4-Mitigation Plan
tion types to classification Level IV of Viereck, Dyrness,
and Batten (1982). Preliminary mapping wi 11 be available in
June 1983 prior to field confirmation during June through
October 1983. It is expected that this mapping wi 11 provide
a det~ led and accurate representation of wetland vegetation
types within the project area at a scale and resolution
satisfactory for Section 404 permit evaluation by the COE in
coordination with the USFWS. Two meetings with representa-
tives of these agencies were held in December 1982 to review
and define plans for the mapping and to initiate consulta-
tion for the purpose of Section 4 permit application plann-
i ng.
It is not anticipated that the Susitna Project will produce
major impacts on wet 1 ands outside the impoundment areas.
Two locations of concern have been identified:
(1) The 14-mi le (22-km) portion of the Denali Highway-
to-Watana access route (MP 24-38) passing near the
Deadman Creek drainage (Figures E.3.80-81); and
(2) The Jack Long Creek area (Figure E.3.82).
Major impacts to wetlands in these areas wi 11 be avoided by
the routing changes and special siting and construction pro-
cedures described in Section 3.4.2( a) (i).
During detailed engineering design and construction plan-
ning, coordination with the COE and USFWS wi 11 continue so
that incorporation of proper engineering design to mitigate
for potential drainage alterations is assured. The high-
resolution wetlands mapping, along with color aerial photo-
graphs, wi 11 be an important tool in this regard. Proper
engineering design and construction planning for wetland
areas are considered to be a top-priority component of the
project civi 1 engineering program.
During detailed alignment studies for the transmission
corridors, project engineers, hydrologists, and
environmental specialists will inspect the corridors from
the air and ground and make site-specific alignment
adjustments to minimize wetland and floodplain crossings.
No fill placement will be associated with transmission
corridor construction.
As explained in SectiDn 3.3.1(b)(iii), regulated flows will
produce changes in vegetation di stri buti on and successional
patterns in the downstream floodplain. These changes wi 11
E-3-290
,.rr-::---
-
-
3.4 -Mi ti gati on Plan
be monitored during the postconstruction years of the
license period in conjunction with ongoing studies of moose,
raptors, and other wildlife by the ADF&G and the USFWS.
Downstream aerial photography of the fl oodpl ai n wi ll be
conducted at ten-year intervals beginning in 1988 to
document and facilitate analysis of floodplain configuration
and vegetation changes in coordination with hydro 1 ogy and
wildlife monitoring.
The effect of fire as a natural process in regulating
patterns of plant succession was discussed in Section
3.3.1(b) (v). Fire control wi 11 be the responsibility of
resource management agencies with juri sdi cti on over pub 1 i c
lands of the project area. The BLM wi 11 be responsible for
control measures associated with the Alphabet Hills burn
{Sections 3.4.2[a][iv] and 4.4.2[b]).· Plans and procedures
for subsequent controlled burning by the Power Authority as
a habitat-enhancement measure wi 11 be closely coordinated
with BLM.
In summary, the highest priority and greatest effort with
respect to mitigation of project-related changes in vegeta-
tion will be in regard to wetlands. Detailed engineering
design and construction planning wi 11 be coordinated with
the COE and USFWS representatives as part of the Section 404
planning process.
3.4.3 -Mitigation Summary
As discussed in Section 3.4.2, project impacts to vegeta-
tion wi 11 be important mainly from the standpoint of loss
of wildlife habitat. Therefore, mitigation plans for
botanical resources have been determined primarily to sup-
port the wildlife mitigation program. Major mitigation
plan elements described in Section 3.4.2 are:
(1) Mini mi zing facility dimensions.
{ 2) Consolidating structures.
(3) Siting facilities in areas of low biomass.
{4) Siting facilities to minimize clearing of less abun-
dant vegetation types.
(5) Siting facilities to minimize clearing of vegetation
types productive as wildlife habitat components.
{6) Minimizing volume requirements for borrow extrac-
tion.
E-3-291
3.4 -Mitigation Plan
(7) Disposal of spoil within the impoundments or
previously excavated areas.
(8) Designing transmission corridors to allow selective
cutting of trees and to accommodate uncleared low
shrub and tundra vegetation within rights-of-way.
(9) Dismantling nonessential structures as soon as they
are vacated.
(10) Development of a comprehensive site rehabilitation
p 1 an.
(11) Monitoring progress of rehabilitation to identify
locations requiring further attention.
(12) Acquisition of replacement lands for implementation
of habitat enhancement measures.
(13) Planning and development of an environmental
briefings program for all field personnel.
(14) Avoidance of the Prairie Creek, Stephan Lake, Fog
Lakes, and Indian River areas by access routing.
(15) Restriction of public access during construction by
gating the access road.
(16) Use of signs and possibly regulatory designations and
measures to discourage use of ORVs and ATVs.
(17) Phased implementation of the project Recreation Plan
with interagency review and concurrence.
(18) Siting and alignment of all facilities to avoid
wetlands to the maximum extent feasible.
(19) Agency coordination and participation in detailed
engineering design and construction planning of civi 1
engineering measures to minimize potential wetlands
impacts.
(20) High-resolution mapping of wetland vegetation within
the project area, in coordination with COE and USFWS
representatives to be conducted in 1983.
Mitigation schedules and costs are presented in Table
E.3.177. A summary of agency consultation is provided in
Section 4.4.4.
E-3-292
4 -WILDLIFE
4.1 -Introduction
Populations of many wildlife species inhabit the Susitna project study
areas, which for wildlife include the watershed of the Susitna River
upstream from Gold Creek (Figure E3.33), a corridor extending approxi-
mately 1 mile (1.6 km) to each side of the downstream flood plain
between Gold Creek and Cook Inlet (Figure E3.34), transmission corridor
study areas 5 miles (8 km) in width from Healy to Fairbanks and Willow
to Anchorage (Figure E3.35). and the intertie transmission corridor
from Willow to Healy, with a study area varying from approximately 4 to
18 miles (6.5 to 29 km) (Figures E3.35 and E3.37). While the
ecological importance of all species that are members of the Susitna
basin community is recognized, the emphasis of this report is on the
wildlife resources which can be assigned priority based on the irrela-
tive abundance, regional rarity, or their contribution to recreation,
susbistence, or commerce. Species classified as threatened or
endangered are considered particularly important.
The complexity of interactions and relationships between species in any
ecosystem necessitates a system of priorities in the development of
mitigation plans. Consequently, some species require less intensive
study then others. The content of Section 4.2, the Baseline Descrip-
tion of wildlife resources, reflects this prioritization of species.
It should be recognized that the priorities assigned are an aid in
developing a mitigation plan with compatible components--with recog-
nized tradeoffs in benefits to some species at the expense of others.
but with as little antagonism between incompatible mitigation measures
as possible.
Data on the vertebrate fauna in the Susitna basin were collected in
several independent investigations. The ADF&G and University of Alaska
reports (listed below) provided most of the data and analysis presented
in this document. Raw data and quantification to support interpreta-
tions are presented whenever these source documents have provided such
numbers. In many instances. such quantification has not been provided
and this discussion then relies on the interpretation of the investi-
gators. In such cases, a reference to the source document is given to
allow the reader access to the same information in its original form.
Data sources are as follows: moose • ADF&G (1982a and 1982b); caribou
-ADF&G (1982c); Dall sheep-ADF&G (1982d); brown bear and black bear
-ADF&G (1982e); wolf -ADF&G (1982f); wolverine -ADF&G (1982g); fur-
bearers-Gipson et al. (1982); and birds and small mammals-Kessel et
al. (1982a and 1982b). The most recent information from these continu-
ing investigations was provided by personal communications and unpub-
lished tables to allow the most up-to-date analysis for this report.
4.1.1 -The Vertebrate Fauna
Birds and mammals are the wildlife groups of interest in this
study. Kessel et al. (1982a, 1982b) encountered 135 species of
birds in the Susitna Basin upstream from Gold Creek (Appendix
3E); 82 species were found along the Susitna River floodplain
E-3-294
-
....
4.1 -Introduction
downstream from Devil Canyon in June 1982 (Appendix 3F). Sixteen
species of small mammals--shrews, rodents, and hares are known to
occur in the middle Susitna Basin (Kessel et al. 1982a). The
middle basin is that area extending outward to the watershed
boundary from the Susitna River between its confluences with the
Tyone River and the Chulitna and Talkeetna Rivers {Figure E.3.3).
Moose, caribou, Dall sheep, .brown bear, black bear, wolf, and
wolverine are big game species that occur in the project area.
Furbearers include beaver, muskrat, river otter, mink, pine mar-
ten, red fox, lynx, coyote, and short-tailed and least weasel
{Gipson et al. 1982). Scientific· names of bird and mammal
species are listed in Appendices 3.E, 3.F, and 3.G.
4.1.2 -Threatened or Endangered Species
No threatened or endangered species of wildlife has been encoun~
tered recently in the Susitna project area. White (1974) obser-
ved two peregrine falcons in 1974 along the Susitna River in the
Devil Canyon impoundment area, and one inactive nest near the
northern transmission line. Kessel et al. (1982a) observed no
peregrine falcons or other threatened or endangered species dur-
ing their 1981 and 1982 studies. The potential presence of
peregrine falcons is discussed in greater detail in Section 4.2.3
(a). With the exception of the peregrine falcon, none of the
species known to occur in the project area is rare, threatened,
or endangered in the state of Alaska.
4.1.3 -Species Contributing to Recreation,
Subsistence and Commerce
All big game species of the project area contribute to recrea-
tion, and the yearly big game harvest contributes to local and
regional subsistence (Exhibit E, Chapter 5). Furbearers contri-
bute to the commerce of fur trappers in the Susitna region. Few
birds are hunted in the project area. In theory, birds contri-
bute to nonconsumptive forms of recreation such as bird-watching,
but the area is too remote to attract many people who come sol ely
to see birds. ·
Moose, caribou, black bear, ·and brown bear are the most abundant
big game species in the project area and are given highest prio-
rity. Dall sheep, wolf, and wolverine are regionally less abun-
dant and are assigned secondary importance. Furbearers are con-
sidered less important than big game species. Beaver, marten,
and muskrat are common enough to be readily available to trappers
but have limited economic importance. Otter, mink, red fox,
coyote, lynx, and weasel are given low priority.
E-3-295
4.2 -Baseline Description
Bird and small mammal species contribute little to consumptive
use in the Susitna basin. Certain bird species, such as bald and
golden eagles (which have received national protection), trump-
eter swans and other waterfowl, can be identified as high profile
species and assigned priority on that basis. Other birds and
small mammals have historically contributed little to recreation,
subsistence, or commerce in the project area. In addition, each
group includes a large number of regionally abundant species of
which few can be assigned priority over others. These factors
preclude a detailed analysis of the biology and anticipated
impacts to individual species of small mammals and birds of the
middle and lower Susitna basin. However, behavioral characteris-
tics of these small-bodied animals, such as small movements and
home range and use of mi era-habitats, serve to justify their
treatment in groups of organisms with superficially similar
requirements that will be affected in similar ways. These biases
in treatment relative to the higher priority species are allevia-
ted somewhat by the fact that mitigation serving to preserve
habitat for larger species will also serve to protect an assem-
blage of the small birds and mammals essential to the maintenance
of a functioning wildlife community.
4.2 -Baseline Description
4. 2. 1 - B i g Game
(a) Moose
Studies of moose in the Susitna Basin have been conducted by
the Alaska Department of Fish and Game in two discrete
areas: (1) the middle and upper Susitna Basin, including
all parts of the watershed upstream from the Devil Canyon
damsite, and {2) the lower Susitna Basin, including the
major valley and floodplain of the Susitna River from Devil
Canyon downstream to the river mouth at Cook Inlet. The
river basin below Devil Canyon can be divided into 3 sec-
tions based on river morphology. Between Devil Canyon and
Talkeetna the river is then characterized by rapid flow in a
single channel less than 500 feet (150m) wide, with widely
separated islands covered with mature forest. The banks are
steep and covered with alder shrub and spruce-birch forests.
Between Talkeetna and Montana Creek the river widens 1. 2
miles (2 km) and becomes braided with many small islands in
a broad floodplain. Below Montana Creek the river is gener-
ally very broad, between 3 and 12 miles (5-19 km), with up
to 15 channels and numerous sloughs and oxbow lakes. Dis-
turbed habitats are much more abundant because of a 1 ong
hi story of settlement and other development effects. Adja-
cent shores and large islands are heavily forested.
E-3-296
....
....
-
4.2 -Baseline Description
Studies in the middle and lower Susitna basins have add-
ressed different aspects of moose ecology. The differences
in approach primarily reflect the differences in topography
and vegetation in each portion of the basin, as well as dif-
ferences in the development scenarios and potential impacts
in the two areas. Consequently, comparable information on
moose in all areas of the Susitna Basin is not always avail-
able. The following discussion of moose ecology in the
Susitna basin provides a summary of the current state of
knowledge for moose in the middle and lower portions of the
basin. Similarities and differences in various aspects of
moose ecology that may be influenced by the Watana and Devil
Canyon projects will also be discussed.
Most of the information contained in the following discus-
sion is based on studies by ADF&G (1982a,b) in the middle
and lower Susitna b_a.sins. Additional studies and communica-
tions are cited as necessary.
(i) Distribution
Moose occur throughout the Susitna River drainage·
and, because of their regional contribution to sub-
sistence, are one of the most economically important
wildlife species in the region (see Chapter 5).
Within the Susitna Basin, moose tend to be most abun-
dant in the upstream area east of and including
Tsusena and Kosina Creeks and within the main Susitna
valley downstream from Montana Creek to the river
mouth at Cook Inlet. Low numbers of moose presently
inhabit the area between Devil Canyon and Talkeetna.
-Seasonal Movements
Moose in many northern areas undergo regular sea-
sonal movements or migrations (see LeResche 1974
and Coady 1982 for a review). LeResche (1974) des-
cribed moose migrations as regular annual movements
that involve return to at 1 east one common area
each year. In some areas such as the Arctic
Coastal Plain of Alaska (Mould 1979) or northern
Minnesota (Van Ballenberghe and Peek 1971), migra-
tory movements may involve distances of only
1.2-6.2 miles (2-10 km) with little change in ele-
vation. Migrations in mountainous areas usually
involve large changes in elevation. Horizontal
differences between summer and winter ranges may be
as little as 1.2 miles (2 krn) (Knowlton 1960) or as
great as 105 miles {170 km) (Barry 1961). In in-
terior Alaska, moose spend the summer at low eleva-
tions, move to high elevations during fall and
E-3-297
4. 2 -Baseline Description
early winter, and return to lo\Er elevations during
mid-to late-winter (Bishop 1969). Migration of
moose appears to be an ad apt at ion to optimize sea-
sonal use of forage habitats (Coady 1982).
Weather conditions, particularly snow depth and
structure, are among the most important factors
associated with moose migration (Coady 1974,
LeResche 1974). Winter severity may influence the
distance moved by individuals as well as the pro-
portions of moose in a population that migrate to
different areas. For excmple, during a winter of
1 ight snow in south-central Alaska, some groups of
moose overwintered on summer ranges ..-i1ile other
groups migrated to adjacent winter range (Van
Ballenberghe 1978). During winters of deep snow,
ho\Ever, almost all of the moose migrated from the
summer ranges to low elevation winter ranges.
In the middle Susitna Basin, some groups of moose
exhibit seasonal shifts in distribution. Other
groups undergo very 1 imited seasonal movenents and
remain in low elevation riparian and forest commu-
nities year-round. ADF&G (1982a) delineated 13
subpopul at ions of moose in the middle Susitna Basin
on the basis of seasonal movenent patterns.
Over 2 700 radio 1 oc at ions obtai ned from 2 07 moose
during the period from October 1976 through August
1981 indicated that most moose in the middle
Susitna Basin moved to lower elevations during late
spring and early SlJTlmer; mean elevations of reloca-
tions for April and May were 2575 feet (785 m) and
2641 feet (805 m), respectively (ADF&G 1982a). As
SlJllmer progressed, moose moved to higher elevation:;
and commonly remained there throughout the winter
period. The highest mean elevation of 2956 feet
(901 m) occurred in December.
These seasonal trends in el ev at ion are quite d if-
ferent from seasonal patterns observed during pre-
vious studies in the middle Susitna and Nelchina
river basins. Van Ballenberghe (1978) and Ballard
and Taylor (1980) both observed that moose tended
to occupy areas at 2500-2999 feet {762-914 m) ele-
vation during the SlJllmer and moved to el ev at ions of
1798-2202 feet {548-671 m) during the winter.
ADF&G {l982a) attributed the use of higher eleva-
tions by moose during 1980 and 1981 to mild
E-3-298
-
-
-
4. 2 -Baseline Description
winters, and suggested that high winds and tempera-
ture inversions resulted in red oced snow depths at
higher el ev ati ons. Browse was consequently more
accessible in these areas than at lo\\er eleva-
tions.
Use of regional areas within the middle Susitna
Basin by moose also appears to be influenced by
slope steepness. Slopes were classified into four
broad categories: flat--0 to 10°, gentle--11 to
30°, moderate--31 to 60°, and steep--61 to 90°.
During both summer (May to August) and winter
(Novenber to April), 91 percent of moose reloca-
tions occurred on flat and gentle slopes (ADF&G
1982a). The aspect of the slope, ho\\ever, did not
appear to influence moose locations.
Detailed information on the distribution of moose
in the 1 O\\er Sus itna Basin is 1 im ited to the cur-
rent studies being sponsored by the Power Author-
ity (A[J'&G 1982b). lll1 unspecified total nUTJber of
relocations for 3 males and 3 females between
mid-April 1980 to mid-March 1981, and 7 males and
25 females between mid-March and October 1981 are
presented by ADF&G (1982b).
In general, riparian habitats are at least season-
ally important to moose in all reaches of the 1 o\\er
Susitna River. Winter ranges for moose throughout
the lower Susitna Basin are located in riparian
areas. Riparian communities are also commonly used
as calving areas by moose north of Talkeetna, as
year-round habitat for moose in the Delta Island
area, and as transition range for moose south of
Ta 1 keetna ( ADF&G 1982b) . (Moose in the area south
of Talkeetna appear to utilize seasonal ranges on
both sides of the river valley.)
-Special Us.e Areas
. Calving Areas
Parturition generally occurred bet\\een May 15 and
June 15 in the year:s 1977 to 1980. To determine
whether calving concentrations occurred in or
adjacent to the prop:>sed impoundment areas, all
observations of radio-collared cowmoose (n=37 in
1980; n=53 in 1981) in the middle Susitna Basin
E-3-299
4.2 -Baseline Description
were plotted (see Figure E.3.86) (ADF&G 1982a).
A 1 though this method includes some cows which
were not observed with ca 1 ves, it does provide
1 ocations of areas where cows probably calve.
(This error is 1 ikely small because calf mortal-
ity immediately following birth is high [Ballard
and Taylor 1980, Ballard et al. 1981a] and many
parturient cows would consequently not be
observed with calves.)
Cow moose were distributed throughout the middle
Susitna Basin, but several concentrations of
radio-collared cow moose were observed (ADF&G
1982a). These included: Coal Creek and its tri-
butaries; the Susitna River frorn the mouth of the
Tyone River downstream to a point several miles
downstream from Clarence Lake Creek; Jay Creek to
Watana Creek; the area in the vicinity of the
mouths of Deadman and Tsusena creeks; Fog Creek
to Stephan Lake; and opposite Fog Creek to Devil
Creek. Low shrub and open spruce habitats were
the most common cover types in the vicinity of
these concentrations. The importance of these
sites as traditional calving areas is not known.
Calving ranges for 36 moose were obtained in the
lower Susitna Basin (ADF&G 1982b). Within the
lower Susitna Basin, calving concentrations up-
stream from Talkeetna occurred in cover types
different from those used downstream from
Talkeetna. Six of 10 females and neither of two
males north of Talkeetna were in riparian habitat
during calving. Only 4 of 21 moose south of
Talkeetna were in riparian habitats during calv-
ing. Radio-collared females upstream from
Talkeetna generally moved to riparian or island
habitats during the calving period (ADF&G 1982b).
Cottonwood was the predominant cover type in the
vicinity of most relocations during the calving
period.
In contrast, radio-collared cow moose in the
Susitna Valley south of Talkeetna generally left
the overwintering riparian areas by late April
and did not return to these areas until well
after the calving period (ADF&G 1982b). A pos-
sible calving concentration was observed in the
vicinity of Trapper Lake, but most cow moose were
widely dispersed at varying distances from the
E-3-300
,..--.-.,
r:-----,-
r----,
-
-I
-
-I
i
-
r
I,
4.2 -Baseline Description
Susitna River (ADF&G 1982b). On average, cow
moose were 1 ocated 9.1 miles ( 14.7 km) from the
river during the calving period. However, sev-
eral females calved on the river islands and
remained there throughout the'year. Cow moose in
the area south of Talkeetna were generally ob-
served in cover types more typi ca 1 of ca 1 vi ng
habitat in other areas of Alaska (e.g., Rausch
1958; Bailey and Bangs 1980); a mosaic of spruce
and alder interspersed with muskeg bog meadows
was the most common cover type near relocations
{ADF&G 1982b). .
A common feature of ca 1 vi ng habitats in the 1 ower
Susitna Basin is their close proximity to water
(ADF&G 1982b). Although the presence of water
may be an important attribute of calving sites,
it is more .. l ikely that cow moose seek these areas
because of the availability of newly growing
herbaceous vegetation (LeResche and Davis 1973,
ADF&G 1982b). Such vegetation would provide
1 actati ng cows and newborn calves with a readily
available source of easily digestible, highly
nutritious forage {Weeks and Kirkpatrick 1976,
Fraser et al. 1980) •
• Breeding Areas
Breeding concentrations in the middle-Susitna
Basin were determined by plotting the locations
of all radio-collared cow moose (n=37 in 1980)
between September 20 and October 20 during 1977
to 1980 (see Figure E.3.87) (ADF&G 1982a). Most
cow moose occupied upland sites away from the
proposed impoundment areas {ADF&G 1982a).
Concentrations occurred in the following areas:
Coal Creek to the big bend in the Susitna River;
Clarence Lake; uplands between Watana and Jay
Creeks; Stephan Lake to Fog Lake; and the uplands
above the mouth of Tsusena Creek. Other
concentration areas away from the proposed
impoundments include northwestern Alphabet Hills,
the Maclaren River, and the area upstream from
the mouth of Valdez Creek (ADF&G 1982a).
In the lower Susitna Basin, few moose were obser-
ved in riparian habitats during the breeding
period (ADF&G 1982b). With the exception of
moose that remained in riparian communities or on
E-3-301
4.2 -Baseline Description
the river islands throughout the year, most moose
were located farther from the Susitna River dur-
ing the rut than during the calving period (ADF&G
1982b). Average distances from the river were
9.6 miles (15.5 km) and 15.4 miles (24.8 km) for
cow and bull moose, respectively. Use of spe-
cific cover types during the breeding period was
not assessed.
-River Crossings
Between October 1976 and December 1981, 33 radi a-
collared moose made a minimum of 73 crossings of
the middle Susitna River. Of 40 river crossings by
radio-collared animals during 1980-1981, all occur-
red during the months of May through November.
Distributions of the crossings were: May -20 per-
cent, June -7. 5 percent, July -12.5 percent,
August -12.5 percent, September -25 percent,
October -12.5 percent, and November -10 percent
(ADF&G 1982a).
Track surveys on March 24, 1981, provided observa-
tions )f an additional 73 crossings of the Susitna
River by moose. Based both on crossings by radio-
collared animals and on track sightings, records of
crossings of the Susitna River occurred throughout
the proposed impoundment areas. However, crossings
tended to be concentrated in severa1 major areas
along the Susitna River; these included from Goose
Creek to Clearwater Creek, Jay to Watana Creeks,
from the mouth of Deadman Creek upstream for
approximately 5 mi 1 es ( 8 km), and the mouth of Fog
Creek downstream to an area near Stephan Lake
(ADF&G 1982a).
Information on movements of radio-collared moose in
the middle Susitna Basin between October 1976 and
mid-August 1981 suggests that some of the above
crossing concentrations may be associated with
migratory movements. In general, movement patterns
of most moose approximated the drainage patterns of
creeks and tributaries of the mainstem rivers
(Figure E.3.88). Consequently, most movements in
the middle Susi tna Basin involved a north-south
movement pattern. Crossing sites for these
genera1ized movements that occur within the pro-
posed impoundment areas include the 1 ower portion
of Watana Creek, the Jay-Kosi na creeks area, and
the movement corridor along the Susitna River. No
E-3-302
....
~
I
!
-!
-
4.2 -Baseline Description
river crossings by moose have been documented in
the reach between Devi 1 Canyon and Portage Creek,
where steep canyon walls physically prevent cros-
sings.
(ii) Habitat Use
-Cover Requirements
Because moose are 1 argely dependent on woody browse
during winter and late spring, their distributions
are more closely associated with the distribution
of commonly utilized browse species than with other
environmental factors {Coady 1982). However, the
minimum requirements of moose for winter food and
cover appear to be satisfied by a great diversity
of habitat types across North America, suggesting
that moose are adaptab 1 e to a variety of condi-
tions.
Habitat use by moose is most extensive areally dur-
ing the summer and fall and is gradually restricted
during the winter (LeResche et al. 1974). Lowland
and upland climax shrub communities are heavily
utilized during summer and fall. By early winter,
moose commonly move to upland and 1 owl and seral
communities. During winters of deep snow, upland
seral communities are abandoned in favor of lowland
areas (ADF&G 1982a).
In western North America, shrub communities are the
most important winter habitats for moose (LeResche
et al. 1974). In particular, riparian willow
(Salix spp.) stands provide high quality winter
range. (However, moose highly prefer some species
of willow over others.) Maximum use of these areas
occurs during mid-to late-winter and during severe
winters. Areas of coniferous forests adjacent to
riparian communities provide bedding areas and
cover and so enhance the value of these shrublands
for moose.
Riparian communities are perhaps the most important
shrub habitats for moose {Coady 1982). Because
riparian areas are frequently disturbed by alluvial
action, they provide permanent seral habitats.
Important seral shrub habitat is also created by
fire, clear-cutting, and other disturbances that
remove climax vegetation cover (LeResche et a 1.
E-3-303
4.2 -Baseline Description
1974, Davis and Franzmann 1979). However, because
moose avoid large clear-cut areas (Hamilton and
Drysdale 1975), widescale removal of mature forest
cover can result in a reduction in moose habitat
value, despite the increase in shrub growth.
Following fire in Alaska, the optimum age of browse
growth is less than 50 years and moose utilization
of these areas usually peaks 20-25 years after
burning (LeResche et al. 1974).
Site-specific information on habitat use by moose
in the middle and lower Susitna basins was based on
aerial assessments of the dominant plant species in
the vicinity of each moose relocation (ADF&G 1982a,
1982b). Although this method of evaluating habitat
use provided some information on the apparent pref-
erence for different forest cover types, two pro-
blems were apparent.
The first problem is associated with diurnal dif-
ferences in habitat use by moose. Linkswiler
( 1982) showed that habitat use by moose in Dena 1 i
National Park was strongly associated with the time
of day. In general, it appeared that moose rested
in forested areas during the day and became active
in more open cover types during the early morning
and evening. Observations of habitat use in the
Susitna Basin consequently may not accurately
reflect the importance of some habitats to moose
for activities such as feeding or nursing, except
during the winter when habitat use is not greatly
influenced by time of day.
The second problem associ a ted with the assessment
of moose habitat use during aerial surveys is that
overstory cover types may not accurately reflect
habitat components, such as browse availability,
that strongly influence use by moose (see Section
4.3.1(a) [iii]). For example, ADF&G (1982a) indi-
cated that the middle Susitna and Nel china River
basins contain approximately 24 species of willow
(Salix spp.); yet moose commonly utilize only a few
species of willow as browse (Wolff 1976). Because
the distributions of willows and other shrubs are
not directly related to forest cover types, assess-
ments of habitat use by moose on the basis of for-
est cover types is probably misleading. Approxi-
mate equivalents for aerially assessed cover types
and Viereck and Dyrness (1980) vegetation types are
shown in Table E.3.87. Complete descriptions of
E-3-304
r--
4.2 -Baseline Description
the plant communities associated with each vegeta-
tion type appear in Tables E.3.53 to E.3.69 •
• Habitat Use in the Middle Susitna Basin
In all seasons, spruce cover types were the areas
most frequently used by 207 radio-collared moose
in the middle Susitna Basin during the period
October 1976 to August 1981, with sparse-and
medium-density, medium-height black spruce (see
Table E.3.88) comprising 40.5 percent of the
total observations (ADF&G 1982a). Assuming that
Linkswiler's (1982) results apply to the Susitna
Basin, spruce habitats likely represent bedding
or resting habitats. The combined areas of ,
conifer forest and. shrubland account for only 59
percent of the total area in the middle Susitna
Basin, but based on the aerial surveys, received
over 90 percent of the year-round use by moose.
Moose use of upland shrub habitats corresponded
closely with observed elevational movements of
moose in this part of the Susitna Basin (Table
E.3.88). Moose were rarely observed in upland
shrub habitats just prior to calving in April
when they tended to be at 1 ow e 1 eva t ions ( ADF &G
1982a). Use of the upland shrub habitat
increased during the summer and peaked in October
when 43 percent of all moose observed were in up-
land shrub habitat {AOF&G 1982a). High propor-
tions of moose observed were in upland shrub
habitat throughout the winter (ADF&G 1982a). As
discussed earlier, the high use of this cover
type during the winter is likely the result of
mild winter conditions and consequently may not
accurately represent moose habitat affinities
during more severe winters.
During calving in May, 140 (52 percent) of 271
moose in the middle Susitna Basin were observed
in sparse-to-medium-density, medium-height spruce
habitats {AOF &G 1982a). These habitats, which
generally occur near the river and its tribu-
taries, may be selected by parturient females
because of the avai 1 abi 1 ity of escape cover and
the early green-up of the vegetation {ADF&G
1982a). Habitats such as birch, alder, and dense
spruce cover types were not commonly used during
the calving period (AOF&G 1982a).
E-3-305
Habitat Use in the Lower Susitna Basin
Habitat use data in the lower Susitna Basin are
derived from relocations of 10 moose captured and
and radio-colla red in April 1980 and 29 moose
captured and collared in March 1981. Winter
relocations are available only for the 10 moose
captured in 1980. Additional data on winter
habitat use in the lower basin are being collect-
ed and will be available in June 1983 (Modafferi
1983, pers. comm.).
Habitat affinities of moose in the lower Susitna
Basin differed among the areas south of and north
of Ta 1 keetna and, in some cases, appeared to be
influenced by both the sex of the animal and the
season (E.3.89, E.3.90 and E.3.91). Because
these results are based on a relatively small
number of relocations for a small number of
moose, differrences in habitat use among male
and fema 1 e moose and among seasons may not be
significant.
Fifty-four relocations were made of the 2 rna 1 e
moose collared north of Talkeetna between mid-
March and mid-October 1981. All relocations were
in nonriparian communities and most were domina-
ted by alder, spruce and birch cover.
Eight females collared north of Talkeetna provid-
ed 217 relocations. One hundred and ninety-six
were in nonriparian communities dominated by
alder, birch, and spruce. Seventy-six percent of
the 21 riparian relocations were during the calv-
ing period. Riparian relocation sites were
dominated by balsam poplar. alder, and willow.
Five males radio-collared south of Talkeetna
provided 160 relocations, 147 in nonriparian
habitats dominated by alder, birch, and spruce.
The 13 riparian relocations were in sites domina-
ted by alder, birch, spruce, and willow (Table
E.3.90). Nineteen females south of Talkeetna
provided 512 relocations. Four hundred and nine
nonriparian relocations were dominated by alder,
birch, and spruce. One hundred and three
riparian relocations were in sites dominated by
alder. spruce, birch, and balsam poplar (Table
E.3.91).
E-3-306
F'"-•-,
-
-
4.2 -Baseline Description
-Food Habits
Moose are primarily browsers, feeding predominantly
on deciduous woody browse during winter months and
on emergent and herbaceous plants as well as leaves
and 1 eaders of shrubs and trees during the summer
(see Peek 1974 for a review). Food habits of moose
are strongly influenced by browse availability, and
thus there are some differences in the importance
of various browse species to moose in the middle
and lower portions of the Susitna Basin.
Browse utilization studies using the point-centered
quarter method were conducted at randomly selected
sites in the middle basin in 1982 (McKendrick 1982
unpublished data). Only twigs at least 19 inches
(50 em) above ground were included, since snow pre-
cluded use of twigs below that height during most
winters. The percent utilization of the most com-
mon moose browse species for all stands combined
(n=2712) were as follows: Richardson willow (9.8
percent); grayleaf willow (8.9 percent);
diamondleaf willow (8.3 percent); Sitka alder (5.3
percent); and resin birch (5.0 percent). Resin
birch is the most common browse species in the
middle basin.
A preliminary estimate of the winter carrying capa-
city for moose of the Watana impoundment zone
(including all borrow areas, camps, village, and
damsite) and the Susitna watershed upstream from
Gold Creek was calculated from browse biomass
estimates (n=678) obtained in 1982 (Table E.3.92).
A detailed description of the methods used to
determine the browse biomass and the assumptions
involved in calculating carrying capacity are
included in Appendix EH. The number of moose-days
the area can support is based on a winter food
intake value of 5.0 kg dry weight per day (Gasaway
and Coady 1974), and includes only the twigs of the
primary browse species listed above. Based on the
assumptions, ihe areas within the impoundment zone
and facilities near the damsite could support a
resident population of 301 moose for 180 winter
days. The upper and middle basins together have a
winter carrying capacity ,of 23,037 resident moose.
This estimate will be greatly improved through the
use of simulation modeling of moose energy and
protein needs (see Section 4.3.1(a) [iii]). The
summer carrying capacity of the impoundment zone
and nearby facilities (based on a daily consumption
of 11 kg dry weight) is about 5 times that
calculated for winter.
E-3-307
4.2 -Baseline Decription
Chatelain (1951) examined rumen contents of moose
obtained from kills along the Alaska railway and
from hunter kills in the lower Susitna Valley in
the Talkeetna-Houston area. Willows, paper birch,
balsam poplar, and trembling aspen constituted most
of the winter diet. Shrubs such as alder, wild
rose, and high-bush cranberry were rarely consumed.
A simi 1 ar analysis by Shepherd ( 1958) a 1 so i ndi-
cated that the winter diet of moose in the 1 ower
Susitna Valley was composed primarily of willows,
paper birch, and trembling aspen. However, because
both of these studies involved moose from nonripar-
i an habitats at some distance from the Susitna
River, they probably do not accurately reflect the
diets of moose overwintering in riparian communi-
ties and on river islands in the Susitna River. In
particular, trembling aspen is not present in
riparian communities and so would be unavailable to
moose as a winter forage.
Browse availability and utilization measurements
were obtained from a number of riparian sample
sites along the Susitna River during 1980 (ADF&G
1981). Five browse species were considered:
willows, balsam poplar, paper birch, highbush cran-
berry, and wild rose. A mean of 0.13 browse
pl antsjft2 (1.4/m2) was recorded for all
habitat types in the Susitna River valley between
Portage Creek and the Delta Islands. Browse
species were most utilized in equisetum/willow and
medium-tall poplar/willow/alder habitats and least
utilized in medium-dense climax poplar/spruce and
sparse climax birch/spruce.
Percent utilization of willow and poplar was great-
est in habitats where they occurred 1 ess frequent-
ly (ADF&G 1981). Birch was seldom found on flood-
plain habitats, but where it occurred near the
river, it was well utilized (26.9 percent). High-
bush cranberry and rose were found mostly in tall
or climax habitats but were 1 ess abundant than
willows. Utilization of highbush cranberry and
rose was also less than that of willows.
General observations indicated that alder was sel-
dom browsed by moose but in some localities a small
alder clump would be heavily browsed (ADF&G 1981).
Some islands with high quality browse were not used
by moose every winter; moose sign on some islands
indicated heavy use in the past but no use during
the winter of 1979-1980.
E-3-308
~'
-
-
-
,, .. ,.
4.2 -Baseline Description
-Home Ranges
Moose population studies in both the middle and
1 ower Susitna basins involved biotelemetry assess-
ment of local and seasonal movements and home
ranges (ADF&G 1982a, 1982b). A considerable volume
of information on home range locations, sizes, and
distance relationships to the proposed impoundments
or river channel was obtained. The following dis-
cussion of home ranges wi 11 con cent rate on the
numbers of home ranges that may be potentially
affected by the impoundments in the middle Susitna
Basin and by modification of riparian communities
in the lower Susitna Basin •
• Middle Susitna Basin
To determine the number of moose that seasonally
and annually occupy areas within or immediately
adjacent to the impoundment areas, ADF&G (1982a)
delineated a 28.7-km (17.8 mile) zone around the
impoundment area. The width of the zone was the
average length of the annual home ranges of 162
radio-collared moose in the middle Susitna Basin
for which four or more observations had been made
during 1980-1981. Based on total home range
polygons for 168 radio-colla red moose-, ADF&G
(1982a) found that 19 had home ranges that fell
outside the 28.7-km (17.8 mile) zone. Of the 149
moose with home range polygons either partially
or entirely within this zone, 79 moose had home
range polygons which were either partly or
entirely contained within an area that encom-
passed the proposed impoundments and an
arbitrarily selected 5-mile (8-km) wide zone
adjacent to the impoundment (8 km is approximate-
ly 1/3 of the average home range 1 ength). Based
on an estimate of 4500 moose for the middle
Susitna Basin, ADF&G (1982a) calculated that up
to 2402 moose may have home ranges that complete-
ly or partly overlap the proposed impoundment
a rea and the area within 5-mi 1 es ( 8-km) of the
impoundment. A number of prob 1 ems concerning
equal catchability of animals, sampling inten-
sity, and emigration/immigration of animals
probably invalidate the results of the above
analysis (ADF&G 1982a). However, it does
pro vi de an appro xi mati on of the number of moose
that could conceivably be affected by the
proposed impoundments and facilities.
E-3-309
4.2 -Baseline Description
• lower Susitna Basin
All moose for which home range data is available
in the lower basin were captured on or
immediately adjacent to the Susitna River on
April 17, 1980 or March 10-12, 1981. Riparian
habitats of the lower basin are assumed to be
winter range used in at least some years by all
of these individuals. Most individuals of both
sexes leave the riparian areas by mid-April
(Table E.3.93), the males leaving 2-3 weeks
earlier than females. ADF&G (1982b) divided the
radio-collared sample into 3 loosely defined
subpopulations, based on capture and relocation
data (Table E.3.94). All of these groups were
found at greatest distances from the Susitna
River in the summer (July 1 to August 31) and/or
breeding (September 14 to October 31) periods.
Downstream westside moose (moose radio-collared
downstream from Talkeetna and spending the
breeding season on the west side of the Susitna
River) were found farther from the river than
other groups; 4 miles (10.74 km) average for 13
females in the breeding period, and 12 miles
(31.5 km) average for 2 males in the summer
period.
Moose collared in the area upstream from
Talkeetna and on the west side of the river were
commonly relocated either within the river down-
stream from Talkeetna (i.e., river islands) or
within 1 mile (1.6 km) of the river (most of this
area would presumably be riparian communities)
(Table E.3.95) (ADF&G 1982b). In contrast, moose
on the east side of the river downstream from
Talkeetna did not commonly frequent the river or
riparian areas (ADF&G 1982b). However, because
of small samples, the above use patterns should
be considered preliminary. Biotelemetry studies
of moose in these riparian communities are
continuing so that the number of moose
potentially influenced by these changes can be
better assessed. These data will be available in
June 1983.
(iii) Population Characteristics
-Historical Population Trends
Although moose population studies specific to much
of the middle Susitna Basin were not initiated
E-3-310
-
-
-i
4.2 -Baseline Description
until the late 1970s, the Alaska Department of Fish
and Game has been conducting annual aerial censuses
in Game Management Unit (GMU) 13 since 1955 (ADF&G
1982a). Portions of GMU 13, specifically Count
Area ( CA) 6, CA 7 and CA 14, occur partly or en-
tirely within the middle Susitna Basin
(Figure E.3.89); survey data for those areas are
presented in Tables E.3.96 through E.3.98.
Historical descriptions of moose populations within
GMU 13 are provided by Rausch (1969), Bishop and
Rausch (1974), Mcilroy (1974), and Ballard and
Taylor (1980). The following discussion is based
on ADF&G (1982a).
During the 1950s, moose populations in GMU 13 in-
creased rapidly and reached high densities about
1960. After the severe winter of 1961-1962, the
population declined and continued to decline with
severe winters occurring in 1965-66, 1970-71, 1971-
72, and 1978-79. Fall cow-calf ratios, as well as
several other indices of population productivity,
declined sharply and reached a record low for the
basin in 1975. Sex and age composition data for
CA 7 and CA 14 have basically exhibited the same
patterns described for the unit. Since 1975, the
moose population appears to have increased slightly
or remained stable, even though calf survival has
remained relatively low.
-Population Estimates -Middle Susitna Basin
In order to obtain accurate estimates of moose pop-
ulation sizes in portions of the middle Susitna
Basin, ADF&G ( 1982a) intensively surveyed CA 7 and
CA 14 during November 5-8, 1980. Moose populations
in all portions of the middle basin were not sur-
veyed because of unfavorable snow conditions and
the high costs of intensively surveying such a
large area. During the aerial surveys of CA 7 and
CA 14, a total of 743 moose were observed within 26
sample areas comprising 234,240 acres (948 km2),
or an equi va 1 ent of 39 percent of the two count
a rea s comb i ned.
A moose census is conducted by first stratifying,
or partitioning, the census area into subunits
(strata) having similar moose densities. Moose
densities within strata designations are relative
values within a particular census area only. The
E-3-311
4.2 -Baseline Description
evaluation of moose densities during a stratifica-
tion flight is based on the number of moose
sighted, the density of moose tracks, vegetation
type and elevation, and prior knowledge of the
area. Each strata contains numerous sample units
(SU), which are areas of 8-20 mi2 (21-52 km2)
aligned around topographic features. A subset of
SUs from each strata are randomly selected to be
intensively surveyed, and the results are then
extrapolated to the entire census area based on the
density estimate for each strata.
Table E.3.99 summarizes the calculations utilized
to estimate the fall moose population in CAs 7 and
14 east of Jay and Kosi na Creeks during the early
winter of 1980. Of the 604,800 acres ( 244 7 km2)
census area, 35 percent was classified as low moose
density, 38 percent as medium moose density, and 27
percent as high moose density. Based upon census
data, each strati fi cation was estimated to contain
the following number of moose/acre: low -0.0045,
medium -0.0075, and high -0.0151 (1.12, 1.85, and
3. 73 moose/km2, respectively). The estimated
total fall population for CAs 7 and 14 was 1986 +
371 (90 percent confidence interval) (ADF&G 1982a)~
Because all moose would not be observed at a survey
intensity of 0.007 min/acre (1.7 minutes/km2),
portions of 10 sample areas were randomly chosen
and were resurveyed at a sampling intensity of
approximately 0.019 min/acre (4.6 minutes/km2)
in an effort to generate a sightability correction
factor. Based on comparisons of total moose counts
during both sets of surveys, it was estimated that
98 percent of the moose were observed during the
first surveys, yielding a correction factor of
1.03. The corrected population estimate for CA 7
and CA 14 was 2046 + 382 (90 percent Cl), of which
22 percent were calves (ADF&G 1982a).
ADF&G (1982a) were unable to intensively census the
portion of the middle Susitna study area west of
Delusion and Kosi na Creeks because of unfavorable
snow conditions, but an estimate of moose numbers
in this area was obtained during a short survey on
November 29, 1980. Stratification of the survey
area indicated that of the 531,200 acres (2150
km2) considered, 359,680 acres (1456 km2) were
E-3-312
r.---,
-
-
-
4.2 -Baseline Description
classified as low densityt 156,160 acres (663
km2) as medium density, and 7,680 acres (7,680
acres) as high-density moose areas. Based on this
stratificationt a crude population estimate of 1151
moose was obtained.
Similar calculations to those described above were
used to estimate the number of moose in CA 6 {ADF&G
1982a). Population estimates for this area were
derived separately because a migratory group of
moose is known to overwinter near the mouth of the
Oshetna River. During the survey on November 9,
1980, a total of 205 moose were observed. Of the
300,800 acres {1217 km2) stratified, 130,560
acres {528 km2) were classified as low-moose
density; . 132,480 acres ( 536 km2) as medi urn-moose
density; and 37,760 acres {153 km2) .as high-moose
density areas. If it is assumed that the moose
stratum densities in CAs 7 and 14 are equivalent to
those in CA 6, a rough estimate of 830 animals is
obtained. The estimated number of moose in the
middle Susitna Basin study area, excluding the far
southeastern portion of the drainage, was 4027 dur-
ing November 1980.
Because of cost constraints and unfavorable snow
conditions, no population estimates were obtained
for a number of areas in the upper Susi tna Basin
{the western Alphabet Hills, the Lake Louise flats,
and the Tyone and Sanona Creek drainages) {ADF&G
1982a).
-Population Estimates -Lower Susitna Basin
Estimates of moose density in the lower Susitna
Basin (Table E.3.100) are based on ten aerial
surveys conducted in riparian communities within
four zones along the 1 ower Susitna River {Figure
E.3.90) (ADF&G 1982b, and unpublished data).
Surveys were flown during periods of snow cover,
since moose are more easily observed at that time,
and greater numbers of moose are using the river.
An average of 267 moose was observed during 6 sur-
veys conducted during the winter of 1981-82 {range
of 82 to 309). These surveys indicate that moose
were generally most abundant along the Susitna
River during early March. Heavy snowfall in
October to December 1982 resulted in much
E-3-313
4.2 -Baseline Description
higher use of the lower river by moose. In early
December 1982, 826 moose were observed within the
survey area. During all surveys, moose densities
were consistently higher downstream from Montana
Creek than between Devil Canyon and Montana Creek.
-Population Structure
• Middle Susitna Basin
Information on the population structure of moose
in a portion of the Susitna Basin {GMU 13) is
available since 1955 (ADF&G 1982a); summaries of
a number of population ratios sue h as cow: ca 1 f
ratios and sex ratios are summarized for CA 6,
CA 7, and CA 14 in Tables E.3.96 to E.3.98. In
all three count areas, the number of males per
100 females has declined substantially since
1955. Declines in the number of calves and twin
calves per 100 females have also been observed.
These data suggest that moose productivity in the
middle Susitna Valley has declined over the past
25 years. Recent declines in productivity have
been attributed largely to brown bear predation
of young calves (Ballard and Spraker 1979;
Ballard et al. 1980, 198la). ADF&G regulates
moose harvest in 13 by limiting the legal
take to large maleSl36-in. wide neck). This
further reduces the number of males per 100
females, but is designed to protect the
productive population because of low recruitment
(due to high predation mortality) •
• Lower Susitna Basin
Information on the sex and age composition of
moose in the lower Susitna Basin was obtained
during the surveys described earlier for popul a-
tion estimates (ADF&G 1982b and unpublished
data). Because composition surveys in the lower
Susitna Basin included only information obtained
during the late fall and winter of each year,
(when males and females are more difficult to
distinguish) only sex and age composition data
from the early surveys in December 1981 and 1982
will be considered (Table E.3.101). Males tended
to be less abundant than females in both years.
Comparisons of the number of calves per 100
females in 1981 for the lower Susitna Basin
(48.4) and the middle Susitna Basin (32.2, based
on estimates from the census surveys) suggest
E-3-314
-
-
4.2 -Baseline Description
that moose populations in the lower Susitna Basin
may be slightly more productive than moose in the
middle basin •
• Mortality Factors
Moose populations in several areas of Alaska,
i ncl udi ng GMU 13 (which includes part of the
Susitna Basin) have undergone population declines
in recent years (Mcilroy 1976). A series of
severe winters during the 1970s was believed to
have resulted in these declines, and low annual
recruitment associated primarily with poor calf
survival prior to November has been suggested as
the predominant factor maintaining these
populations at low levels (Ballard et al. 1980).
Predation· of moose calves by wolf and brown bear
is believed to be the most important factor
contributing to low calf survival. Other factors
such as decreasing range quality, low bull:cow
ratios, and periodic severe winters are thought
to be less important influences on calf survival
(Mcll roy 1974).
Intensive studies of moose populations in the
Nelchina Basin were undertaken by the Alaska
Department of Fish and Game during the mid-1970s
to determine which factors were most important in
determining calf survival. Studies by. Van
Ballenberghe (1978) and Ballard and Taylor (1978)
suggested that bull :cow ratios were not a major
influence on population productivity. Several
measures of physical condition of moose also sug-
gested that moose in the Nelchina Basin were in
good physical condition and that deteriorating
range conditions were not a problem (Franzmann
and LeResche 1978). Furthermore, artificial
reductions in wo 1f populations resu]ted in no
large increases in calf survival, suggesting that
although moose were an important component of
wolves• diets, wolf predation on moose was not a
major factor in declining productivity (Ballard
and Spraker 1979). In the course of these inves-
tigations, it became apparent that brown bear
predation of young moose calves was a major
source of calf mortality (Ballard and Taylor
1978, Spraker and Ballard 1979). A recent study
of moose calf mortality in the Nelchina and upper
Susitna River basins (Ballard et al. 1980) showed
that of 136 calves radio-collared shortly after
parturition, 55 percent died of natura1 causes by
E-3-315
4.2 -Baseline Description
the following November. Brown bear predation of
moose calves accounted for 79 percent of the
natural deaths.
Mortality of newborn moose calves in the middle
Susitna Basin ·during 1980 and 1981 was high
(ADF&G 1982a). By August 1, 1980, 23 (77
percent) of the calves were missing. Rates of
1980 calf loss were compared with those observed
in 1977 and 1978 {Figure E3.91). Although causes
of moose calf mortality were not determined in
1980, the pattern of loss was quite similar to
that observed in GMU 13 during 1977 and 1978
where predation by brown bear accounted for a
high proportion of the natural calf deaths
(Ballard et al. 1981a).
Calf mortality was not directly monitored during
1981 but indices of calf production suggest that
brown bear predation may again have accounted for
a large proportion of the natural deaths (ADF&G
1982a). Of the 46 sexually mature cow moose
which could have produced calves, only 20 {43.5
percent) were observed with calves; four {20 per-
cent) produced twins. The calving rate for known
producers was 1.2 calves/cow. Of the 24 known
calves, 14 {58.3 percent) were missing by July
28. This pattern of calf loss is again quite
similar to that of 1977, 1978, and 1980 when pre-
dation by bears accounted for most of the
1 osses.
Although predation by brown bears does appear to
be the major cause of calf moose mortality during
the summer and fall periods, winter severity is
likely an important factor in determining produc-
tivity and survival. Ballard et al. {1981a)
found that snow depths from the Monahan Flats
a rea were s i gni fi cantly correlated with subse-
quent fall calf:cow ratios in CA 3 of GMU 13.
During the period from 1970 to 1978, 45 percent
of the variation in cow:calf ratios could be
attributed to snow depth. Snow may alter the
energy balance of moose by increasing metabolic
requirements for locomotion and decreasing acces-
sible energy reserves by limiting food availabil-
ity (Coady 1974). Assuming that snow depths are
an adequate index of winter severity, the strong
relationship between cow:calf ratios and snow
depths suggest that overwinter conditions and
their influence on the condition of pregnant cows
are an important factor in determining calf
E-3-316
f'--·,
.....
.....
-
-
4.2 -Baseline Description
survival, and hence, population productivity. As
discussed earlier, winters during the two years
of study of moose populations in the middle
Susitna Basin have been mild. Consequently, it
has not been possible to obtain site-specific
information on the influence of severe winter
conditions on population productivity, habitat
use, or browse utilization.
Ballard and Taylor (1980) examined mortality
rates of adult females based on the loss of
radio-tagged cows in the middle Susitna Basin
during.l976-1978. During the three-year study,
they estimated that annual adult cow mortality
averaged 6 percent.
No instances of predation of calves or adult
moose in the lower Susitna Basin were observed
during 1981 or early 1982. ADF&G (1982b) sug-
gests, however, that most predation which does
occur in the lower Susitna Basin is probably
attributable to brown bears and black bears.
Both species of bear. occur throughout the lower
Susitna Basin; whereas wolves, another major
predator of some moose populations, are rare.
-Dispersal
Limited evidence obtained during the radio-tracking
program suggest that young moose from the middle
Susitna basin may disperse into other major drain-
ages in the region (ADF&G 1982a). One male calf
was observed to move 46.5 miles (75 km) from Swim-
ming Bear Lake t.o Coal Lake. Another male calf
moved from near the mouth of Watana Creek to the
upper reaches of Windy and Clearwater Creeks north
of the Denali Highway.
Based on these 2 observations, ADF&G (1982a)
suggests that moose populations in other drainages
removed from the Susitna drainage may be partly
dependent on the immigration of Susitna moose.
Information on population sizes in the Susitna
Basin during 1980 and 1981 similarly suggest that a
portion of the increase in numbers of adult moose
may have been the result of immigration from other
areas. During 1980, 178 calves and 766 adults were
observed in CA 7. In 1981, a total of 1006 adults
were observed. Even if all of the 1980 calves had
survived (which is unlikely), the increase is 21.1
percent greater than expected. Although sampling
E-3-317
4.2 -Baseline Description
(b) Caribou
errors might account for a major portion of this
difference, immigration from adjacent areas may
partly explain this increase in adult moose.
Evidence from moose studies in areas adjacent to
the 1 ower Susitna Basin suggest that the lower
Susitna population is ~iscrete from those in
adjacent drainages. Moose-tagging studies in the
Matanuska River valley (Rausch 1971) and in the
Peter-Dutch Hi 11 s (Di dri ckson and Taylor 1978)
found that emigration from these areas to the
Susitna Basin was extremely low to nil.
Caribou in the area affected by the proposed Susitna Hydro-
electric Project are members of the Nelchina herd. This
herd, one of 22 herds in Alaska (Davis 1978), is important
to sport and subsistence hunters because of its size and
proximity to population centers in south-central Alaska.
Currently, the Nelchina herd contains about 21,000 animals
(approximately 6 percent of the total statewide caribou
population of 325,000).
Despite the great interest by hunters in harvesting Nelchina
caribou (6662 applications for 1600 permits in 1981), the
range remains relatively inaccessible. Human development is
largely limited to the peripheries and consists primarily of
the Alaska Railroad, Parks Highway, Denali Highway, Richard-
son Highway, Trans-Alaska Pipeline, and Glenn Highway.
Caribou studies for the Susitna project were conducted by
ADF&G (1982c). All data in this section not otherwise cited
were obtai ned from that source. Data from that report are
derived from 659 radio-locations of 41 individuals (an aver-
age of 16.5 locations for each individual, range 7 to 26),
which were collared for varying amounts of time between
April 1980 and September 1981. Thirty-two were caribou from
the main Nelchina herd, 3 from the upper Talkeetna River, 3
from the Chunil na Hills, and 3 from the upper Susitna -
Nenana area.
(i) Distribution and Movement Patterns
The Nel china herd occupies an area of approximately
12,800,000 acres (51,800 km2) bounded by 4 mountain
ranges: the Alaska Range to the north, the Wrangell
Mountains on the east, the Chugach Mountains to the
south, and the Talkeetna Mountains to the west
(Figure E.3.92). The Nelchina range contains a
variety of habitats, from spruce-covered lowlands to
steep, barren mountains.
E-3-318
-
-
-
.....
....
4.2 -Baseline Description
The Nelchina herd has been studied by the U.S. Fish
and Wi 1 dl i fe Service and the A 1 ask a Department of
Fish and Game since 1948. During this time, it has
remained essentially within the area outlined above;
however, with the exception of the calving area,
seasonal use of particular areas has varied.
Early records indicate that the herd wintered
(January to March) in the upper Nenana River area in
the early 1930s and in the Talkeetna Mountains in the
late 1930s (Skoog 1968). From 1950-1955, the herd
wintered from the Little Nelchina River and Glenn
Highway north through the Lake Louise Flats to the
Denali Highway. As the herd increased in size
through the later 1950s and early 1960s, its winter
range also increased in size, encompassing the upper
Nenana River area~ Monahan Flats, Talkeetna Moun-
tains, and extending east across the Richardson
Highway (Hemming 1971). The most recent studies of
radio-collared caribou in 1981 and 1982 indicate that
over 85 percent of the caribou in the herd wintered
(1) on the Lake Louise Flats and the middle portion
of the Gakona and Chistochina River drainages and (2)
in the western foothills of the Alphabet Hills, areas
distant from the proposed impoundments (K. Pitcher
1982 pers. comm.).
Si nee 1949, the first year for which records are
available, Nelchina caribou have utilized an area of
about 640,000 acres (1609 km2o in the northern
Talkeetna Mountains for calving (Skoog 1968, Hemming
1971, Bos 1974). Although the precise areas used
have varied, calving has taken place between Fog
Lakes and the Little Nel china River between about
3000 and 4500 feet elevation. The only deviations
have been during years with extremely heavy snow
accumulations when some calving took place during the
migration to the traditional calving grounds (Lentfer
1965, Skoog 1968, Bos 1973). In 1980 and 1981, calv-
ing took place between May IS and June 10 in the
drainages of Kosina Creek, Goose Creek, Black River,
and Oshetna River (Figure E.3.93) (ADF&G 1982c).
The primary migratory route in 1980 and 1981 from
winter range on the Lake Louise F~ats to the calving
grounds in the eastern Talkeetna Mountains was west-
ward across the flats from Crosswind Lake and Lake
Louise into the Ta 1 keetna Mountains on a front from
Lone Butte to Kosina Creek (ADF&G 1982c).
E-3-319
4.2 -Baseline Description
It appeared that many animals used the frozen Susitna
River between the Oshetna River and Kosina Creek as a
travel route in the spring of 1981 (ADF&G 1982c). In
the spring of 1980 one radio-collared animal, and
presumably also a small portion of the main herd,
moved south and crossed the Susitna River near the
mouth of Deadman Creek. Many animals historically
used this route to the calving grounds after winter-
ing in upper Susitna-Nenana drainages (Skoog 1968).
During spring migration and calving, there is some
segregation of sex and age groups. Although year-
lings and barren cows lag somewhat behind parturient
cows, they also move to the calving area, remaining
scattered along its periphery (Skoog 1968). Radi a-
collared Nelchina bulls were found in a wide variety
of locations mostly in transit to summer ranges dur-
ing calving in 1980 ard 1981 (ADF&G 1982c).
Historically, the female-calf segment of the Nelchina
herd has summered primarily in two areas: the eastern
Talkeetna Mountains and across the Susitna River in
the Brushkana, Butte, Deadman, Watana, Jay, and Coal
Creeks complex (Skoog 1968, Hemming 1971). In most
years between 1950 and 1973, varying proportions of
the female-calf segment (ranging from 0-100 percent)
crossed the Susitna River from the calving grounds to
the summer range on the north side of the river. The
female-calf segment of the Nelchina herd spent the
summer period (June 11 through July 31) of both 1980
and 1981 in the northern and eastern slopes of the
Talkeetna Mountains (ADF&G 1982c). Summering radio-
collared males were found in many locations in the
high country of the Nelchina Basin.
In both 1980 and 1981, autumn {August 1 through
September 31) was a time of considerable movement and
dispersal by both cows and bulls {ADF&G 1982c). Com-
pared to the obvious segregation in June and July, it
appeared that considerable mingling of the sexes
occurred. In mid-to-late August 1980, a portion of
the rna in summering concentrations moved out of the
Talkeetna Mountains onto the western portion of the
Lake Louise Flats, and in some cases, into the
Alphabet Hills. Through September, the distribution
remained relatively stable, with the main herd
divided between the northeastern Talkeetna Mountains,
the Lake Louise Flats, and the Alphabet Hills.
E-3-320
-
-I
4.2 -Baseline Description
(iii)
data. Pitcher estimated that 2500 caribou were in
the count area, based on an actual count of 2077
caribou and his subjective impressions of sightabi-
lity and area coverage.
During early May 1980, four adult fema 1 es and one
adult male were radio-collared from this subherd
(ADF&G 1982c). One of the females migrated to the
main Nelchina calving area, summered in the Talkeetna
Mountains, migrated back through the upper Susitna-
Nenana area in the fall, and rejoined the main
Nelchina herd on the Lake Louise Flats during the rut
and early winter. The other three females remained
in the upper Susitna-Nenana area throughout the study
period, producing two calves in 1980 and two in 1981.
The bull summered in the Clearwater Mountains, then
joined the main Nelchina herd during the rut on the
Lake Louise Flats.
The Chun il na Hills group appears to be a resident
subherd numbering fewer than 340 animals (ADF&G
1982c). One radio-collared bull remained in the
Chunilna Hills from April to November 1980 when it
shed its collar. Two females were collared in the
spring of 1981, both of which subsequently gave birth
to calves in the area. No overlap with radio-
collared animals from the main herd or other subherds
was noted, although one female did move across the
Talkeetna River.
Small groups of caribou, including cows and calves,
have been seen in most of the side drainages of the
upper Talkeetna River. This appears to be another
resident subherd, probably of fewer than 400 animals,
and having some spatial overlap with the main
Nelchina herd. Three caribou in this upper Talkeetna
River subherd (two adult females and one adult male)
were collared on April 18, 1980 (ADF&G 1982c). These
animals were relocated 50 times and were always found
in drainages of the upper Talkeetna River or in the
upper reaches of the nearby Chickaloon River (Figure
E.3.94. One female raised a calf in 1980, and both
raised calves in 1981. The male spent the summer of
1980 in the mountains west of the Talkeetna River.
Habitat Use
Habitat use was analyzed from aerial determination of
vegetation cover at each caribou relocation (ADF&G
1982c).
E-3-321
4.2 -Baseline Description
At one time or another during their annual movements,
Nelchina caribou probably use most of the vegetation
types in the Susitna area. However, ADF&G (1982c)
found caribou mostly in spruce forest, shrub 1 and,
herbaceous vegetation types, and bare substrate
types, with virtually no use of mixed or deciduous
forests.
Nelchina caribou show considerable variation in habi-
tat types used seasonally, and types used most by
bulls are different from types used most by cows
(Table E.3.102) (ADF&G 1982c). Bulls tend to use
spruce forests more than cows in all seasons except
autumn, whereas cow use of tundra-herbaceous types is
greater during all seasons than bull use. These
differences are 1 ikely a reflection of the tendency
of bulls to remain much longer in the forested
wintering areas and to summer at lower elevations
than cows (see Figure E.3.95). Use of shrubland is
similar for cows and bulls overall but differs
seasonally. Bulls tend to use this habitat most in·
summer and autumn, whereas cows use it most during
spring, calving, and summer (ADF&G 1982c).
As mentioned, differences between bulls and cows in
habitat use were partly related to differences in
elevation. The sexes occurred at about the same ele-
vations during autumn, the rut, and winter, but
females were consistently found at higher elevations
during spring migration, calving, and summer (Figure
E.3.95) (ADF&G 1982c).
The food habits of caribou vary seasonally with
available plant forage (Skoog 1968). In spring and
summer, grasses, sedges and the buds of willow and
birch are important, and a wide variety of forbs are
eaten as they become available. Except during years
of late snowmelt when new growth is slow to appear,
lichens are unimportant in the spring diet. In late
summer, mushrooms are an actively sought, but minor,
diet item. During autumn. browse becomes less impor-
tant but sedges and grasses remain major diet compo-
nents and lichens assume greater importance. Through
the winter the diet of Nelchina caribou consists of
about equal portions of graminoids and lichens (Skoog
1968).
(iv) Population Characteristics
The Nelchina herd was estimated to consist of about
E-3-322
-
-
!"""
I
I
""" I
I
4.2 -Baseline Description
40,000 anima 1 s when first surveyed in 1955. Subse-
quently, the herd grew to 71,000 in 1962, decreased
to about 7700 in 1973, and currently numbers about
21,000 (Table E.3.103) (ADF&G 1982c). The management
plan for the Nelchina herd (ADF&G 1976) calls for
maintenance of the herd at about 20,000 adult animals
through harvest of the annual increment.
The sex and age composition of the Nelchina herd re-
mained almost the same from fall 1980 to fall 1981.
Cows and bulls older than one year comprised 49.1
percent and 29.9 percent, respectively, of the herd
in October 1981. Calves comprised 21.1 percent or
42.9 calves per hundred fema 1 es one year and older
(ADF&G 1982c). The proportion of bulls was high com-
pared to the proportion observed in earlier years, a
finding that would be expected in a growing popul a-
tion that had previously had a low proportion of
males (Bergerud 1980).
Skoog (1968) estimated the overall pregnancy rate of
Nelchina caribou to be 72 percent for females one
year and older from 1957 to 1962. Full reproductive
potential was not realized even in the fully adult
age classes. Only 13 percent of yearling females
were pregnant compared to 61 percent of two-year-olds
and 89 percent of females three years and older. In
1980 and 1981, the proportion of calves in the post-
calving aggregations averaged about 56 calves per 100
females one year and older (ADF&G 1982c). These data
suggest that considerable calf mortality occurs
shortly after birth. K. Pitcher (1982 pers. comm.)
estimated that calf survival to 11 months was 43
percent for 1980 calves and 60 percent for 1981
calves. Survival rates for older caribou (>1 year)
were 93.5 percent for females and 87 percent for
males.
Survival rates of caribou are influenced by many fac-
tors including disease,, parasitism, weather, acci-·
dents, food availability, predation, and hunting.
Paras it ism and disease may kill a few caribou each
year in the Nelchina herd, but these are not major
mortality factors. Wet, cold weath.er during calving
can result in high levels of calf mortality which
Skoog ( 1968) believed could ultimately control cari ....
bou population levels. However, this is a factor
that is more likely to affect coastal herds and more
northerly herds than the Nelchina herd (Skoog 1968).
E-3-323
4.2 -Baseline Description
The major factors that are believed to control
caribou mortality and, ultimately, population levels,
both in Alaska and elsewhere, are food availability
and predation (including hunting). In mainland North
America, the population density of most caribou herds
appears to be much below range-carrying capacity and,
indeed, in many herds is much less than the range has
historically supported (e.g., Parker 1972, LeResche
1975, Bergerud 1980). Food availability in winter,
because of snow cover, is likely to be more critical
than availability in summer, and many early workers
speculated that declines in caribou numbers in North
America in the early 1900s were caused by winter
forage (mainly lichen) destruction by forest fires
(Scatter 1967). However, evaluations of more rigor-
ous analyses (e.g., Henshaw 1968, Kelsall and Klein
1979, Klein 1967, Roby 1980, and Bergerud 1974a) show
that starvation or even observable debi 1 itati on in
caribou during winter is rare except in populations
insulated from predators and prevented from dispers-
ing to unoccupied habitats (Scheffer 1951, Klein
1968, Leader-Williams 1980).
Skoog (1968) believed that neither overgrazing nor
fire had greatly affected the Nel china range in the
early 1960s. The herd was considerably 1 arger than
now, and food availability is unlikely to be a major
factor affecting survival in the present herd.
Several authors have presented evidence that caribou
numbers are effectively controlled by predation. For
example, Kelsall (1968), Parker (1972), Miller and
Broughton (1974), and Davis et al. (1980) all report
evidence that caribou numbers have declines as preda-
tor (mainly wolf) numbers increased, or that caribou
numbers have increased as predator numbers decreased.
Bergerud, in two reviews (1974a, 1980), demonstrates
convincingly that where capable predators (wolves,
bears, lynx) are common and hunting by man is insig-
nificant, caribou populations are effectively regu-
lated by predation.
Since the introduction of firearms to North America,
hunting has probably been the major cause of popula-
tion declines (Bergerud 1974a, Calef 1980). Calef
(1980) reported that in some herds in the Northwest
Territories, hunter kill is in excess of annual
recruitment. Doerr (1980) isolated excessive hunting
as the primary cause of population declines in the
Nelchina and Western Arcic herds in Alaska.
E-3-324
p:;,
-
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-
4.2-Ba~eline Description
(c)
Hunting and wo 1 f predation probably account for about
equal portions of the annual mortality of the present
Nelchina herd (ADF&G 1982c). Table E.3.104 shows the
1 evel of hunter harvest from 1972 to 1981. During
that time, hunter harvest in years for which herd
size data are available has varied from 1.4 percent
to 9.6 percent of the herd. Hunter harvest was about
4 percent in 1981.
Wolf predation has reportedly varied with the size of
the wolf population (ADF&G 1982c). Skoog (1968)
estimated that wolves took 1.1 -2.6 percent of the
herd from 1957 -1962. More recently ADF&G {1982f)
estimated wolf predation rates varying from 7 -10
percent ·Of the herd in 1973 to 2 - 3 percent in 1981.
There appears to be no clear relationship between
wolf and caribou population levels, apparently due to
the high harvest of wolves and, in particular, way
control measures in the early 1950 1 s, appears in
(Figure E.3.96). (Bergerud 1980).
The average natural mortality rate for caribou 1 year
and older of both sexes in 1981 was 8.1 percent. If
ADF&G ( 1982f) estimate of 2 - 3 percent mortality
applies to adults as well as calves (as they sug-
gest), then wolf predation combined with hunter har-
vest (3. 9 percent--Tab 1 e E .3 .104) account for 50-60
percent of the annual adult mortality in the Nelchina
herd.
Dall Sheep
Da 11 sheep studies were conducted in the middle Su si tna
River basin during the summer of 1980, spring and summer of
1981, and spring of 1982 (ADF&G 1982d, ADF&G unpublished
data). The purpose of these studies was to determine the
locations and seasons when sheep might be affected by proj-
ect activities. The study area includes all drainages flow-
ing into the Susitna River between Kosina Creek and Gold
Creek and all drainages west of the Su sitna River between
the Denali Highway and Kosi na Creek. Survey efforts were
confined to areas of known or suspected Dall sheep habitat
within this area (Figure E.3.97) (ADF&G 1982d). These
areas contain semi-open~ precipitous terrain, with rocky
slopes, ridges, and cliffs.
E-3-325
4.2-Baseline Description
(i) Distribution
There are three general areas in the middle Susitna
Basin that have steep rocky slopes at sufficient ele-
vation to be potential Dall sheep habitat {ADF&G
1982d). The first of these areas is north of the
Su sitna River between the proposed Devi 1 Canyon and
Watana damsites. Aerial surveys were conducted in
this area in the Portage Creek and Tsu sen a Creek
drainages (Figure E.3.97). The second potential site
for Dall sheep is in the mountains between the
Susitna and Talkeetna Rivers, extending eastward from
the Fog Lakes to Kosi na Creek. The third area is
north of the Su sitna River, to the east of Watana
Creek. This area was established as a population
trend count a rea for Oa 11 sheep by ADF &G i n 1967
(Figure E.3.97).
ADF&G (1982d unpublished data) conducted aerial sur-
veys to determine the seasonal distribution and abun-
dance of Oall sheep in the areas described above on
July 22-23, 1980; on March 13 and 25, 1981; between
May 13 and June 24, 1981; on July 28, 1981; and on
March 23. 1982. The date, locationt number, sex, and
age of sheep were recorded for all sightings (ADF&G
1982d).
A total of 72 sheep (7 legal rams, 12 lambs, and 54
unidentified) were counted in the Portage Creek and
Tsusena Creek drainages in July 1980. Four sheep
were seen north of Portage Creek, two east of Tsusena
Creek, and the other 66 were seen in the headwaters
region of Tsusena Creek. The only previous ADF&G
survey in th·i s area was a 1977 count of 91 sheep (8
legal rams, 18 lambs, 65 others). The 1977 survey
included the Jack River drainage (north of Tsusena
Creek). which was not surveyed in 1980. All of the
sightings were far from the pro~osed impoundments and
access roads.
During July 1980, only eight sheep (1 ram, 7 uniden-
tified) were observed in the Watana Mountain -Grebe
Mountain area. This area is used by sheep from a
larger Talkeetna Mountains population. Ear1ier ob-
servations in 1977 suggested that at least 34 sheep
were present on Mt. Watana. NUmerous observations of
sheep in the Terrace Creek area {a southern tributary
of Kosi na Creek) have been made, but no sheep were
observed during the 1980 survey.
E 3--326
-
-
-
-
-
-
-
4.2-Baseline Description
On March 25, 1981, a winter distribution survey was
conducted in the same area surveyed in July 1980.
Twenty-two sheep were sighted, and two groups of 3-4
tracks were seen. These data suggest that groups of
sheep from the larger Talkeetna Mountains po!).llation
are migrating into the area during winter. All sheep
observations were located on the southern extreme of
the count area, well away from the impoundment.
The Watana Hills area has been surveyed for Dall
sheep by ADF&G yearly since 1967 (ADF&G 1982d). The
data from the 1980 and 1981 surveys show the same
general patterns as previous surveys (Table E.3.105).
The 1981 count of 209 sheep was the second highest
number of sheep recorded for this a ea. The percen-
tage of lambs was similar to that of past years and
suggests that productivity and survival are remaining
constant. The small number of 1 egal rams counted
could reflect the rather high (13) sport harvest
taken from this area in 1980 (R. Tobey 1982 pers.
comm.). Although the 1981 count was relatively high,
it is suspected that the population has remained
stable or perhaps increased slightly (ADF&G 1982d).
Sheep in the Watana Hills area were surveyed in March
of 1981 and 1982. Eighty-seven sheep were sighted in
1981 and 77 in 1982, all on south-facing slopes.
Geist {1971a) suggested that south-facing slopes are
an important part of Da 11 sheep winter range. They
provide maximum exposure to winter sun and frequently
have shallower snow than slopes with different
aspects. Fewer sheep were observed than in the
summer surveys, probably because of poor observabi-
lity due to snow cover and/or movement of sheep from
the area.
(ii) Mineral Lick Use
Mineral licks are known to be ·important for Dall
sheep and are a common component of Spring ranges.
Heimer {1973) suggested that they be considered a
critical habitat requirement. The sheep in the
Watana Hi 11 s a rea have been observed frequenting a
mineral lick along the lower elevations of Jay Creek
at an elevation of about 2200 feet {671 m) • .
The Jay Creek mineral lick was overflown from May 6
through June 24, 1980; the number, sex, and age of
fhe sheep recorded are shown in Table E.3.18 (ADF&G
E-3-327
4.2 -Baseline Description
1982d). Sheep were sighted on 28 of 33 occasions (85
percent). The 1argest single group observed was 15,
representing approximate1y 7 percent of the observed
Watana Hills summer population, and approximately 17
percent of the observed winter po IXJl at ion.
Sheep were observed frequenting other locations adja-
cent to the Jay Creek mineral site (ADF&G 1982d). On
May 23 and 25, 1981, groups of 6 and 12 rams, respec-
tively, were observed scraping and eating soil on the
ridge located on the east side of Jay Creek at an
elevation of 2270 feet (692 m}, directly opposite the
main lick area (Table E.3.106). Since only rams were
observed on these 2 occasions, the observation could
represent a preferential use of certain areas by sex
or age classes. A1so, on 6 days in June, sheep of
different age classes were observed at an area
approximately 2 miles (3.2 km) upstream from the main
mineral area (Table E.3.106). This area also appears
to be mineralized.
No sheep were observed at the Jay Creek drea during
an aeria1 survey of summer distribution on July 28,
1982. However, ten ewes and yearlings were observed
actively utilizing a known mineral lick in the drain-
age of the east fork of Watana Creek, approximately
7 miles (11.3 km) north of the Jay Creek site.
The Jay Creek minera1 lick was also visited by ADF&G
biologists on May 9, 1981. Sheep usage of the area
ranged from the Jay Creek streambed 2000 feet (610
m), to the top of the b 1u ff 2450 feet (747 m), and
for an undetermined distance away from the b 1 u ff.
Signs of heavy moose utilization were evident as
we1l.
{d) Brown Bear
Most of the site-specific information for brown bears in the
Susitna Basin was obtained from recent studies by ADF&G
(1982e). Additional site-specific information was obtained
from studies in the upper Susitna and Nelchina River basins
during 1979 (Miller and Ballard 1980, Spraker et al. 1981).
( i) Distribution
Brown bears or grizzly bears (the former term wi11 be
used throughout this report) are widely distributed
and abundant in most parts of Alaska. Brown bears
E-3-328
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4.2-Baseline Description
appear best adapted to relatively open, undisturbed
areas with good cover and an abundance of perennial
succulent herbs and/or fruit-bearing shrubs (Mealy et
al. 1981). The omnivorous food habits of brown
bears as well as their nongregarious social structure
and high degree of mobility allow them to utilize
resources in a large number of habitats throughout an
expansive area (Knight 1980). Brown bears appear to
be able to adapt to a variety of man-caused
disturbances in their habitat. However, experience
has amply demonstrated that brown bear abundance is
usually incompatible with human presence; human-bear
interactions commonly have resulted in the
extermination of brown bears from sett 1 ed areas
through intensive hunting, trapping, and/or poisoning
programs.
Brown bear research in the middle Susitna and
Nelchina River basins has been ongoing since 1978
{Ballard et al. 1980, Spraker et al. 1981). Most
studies were initially concerned with the effects of
brown bear predation on moose, but more recent
studies have concentrated on all aspects of brown
bear ecology (ADF&G 1982e). No site-specific infor-
mation is available on brown bear in the lower
Susitna Basin. Within the middle Susitna Basin,
brown bears generally are most abundant in open
tundra habitats during most of the late spring and
early fall periods. Many brown bears appear to
utilize lower elevation spruce habitats during the
early spring. Current information suggests that
brown bears in the middle Susitna Basin are abundant
and that populations are young and productive.
-Seasonal Movements
The brown bear's omnivorous feeding habits, social
structure, behavioral interactions, and winter den-
ni ng requirements necessitate extensive movements
throughout large areas (Craighead and Mitchell
1982). It appears that the utilization patterns of
1 arge geographic areas by brown bears is 1 argely
dependent on the spatial and temporal availability
of food. Information from a number of areas in
Canada and the United States suggests that brown
bears establish traditional movements to exploit
dependable sources of food. Often these food
sources are only seasonally available for short
periods of time. Extensive traditional movements
are common in many populations of brown bear
(Pearson 1976, Reynolds 1979, Craighead 1980).
E-3-329
4.2-Baseline Description
Based on 530 relocations of radio-collared brown
bears in the middle Susitna Basin during 1980
(n=15) and 1981 (n=18), ADF&G (1982e) documented
regular seasonal movements of brown bears that
appeared to be associated with regional and eleva-
tional differences in food availability. Movements
of brown bears from the middle Su sitna Basin to
P ra i ri e Creek during Ju 1 y and August were perhaps
the most notable regional movements observed during
the study. These regu 1 ar seasonal movements of
brown bears appeared to be associ a ted with high
concentrations of spawning king salmon in Prai'rie
Creek during this time of year.
Although bad flying conditions in 1981 prevented
complete documentation of the number of brown bears
that move the middle Susitna Basin to Prairie
Creek, 3 of 11 (27 percent) of the radio-call ared
bears were found in the Prairie Creek area sometime
between July and December in 1980 (exact dates not
given), and 2 of these same i ndi vidual s (of 18
collared bears, 11 percent) were found there some-
time between July and December 1981 (ADF&G 1982e).
Local residents report that large concentrations of
brown bears occur in the area during king salmon
runs in July and August. Although a large number
of animals may utilize this food source, it is not
clear whether brown bears are dependent on the
supply of salmon. For example, moderately dense
brown bear populations exist in the adjacent
Nelchina Basin without access to salmon (Miller and
Ballard 1982). As suggested by ADF&G (1982e),
Prairie Creek salmon may be an important buffer
when other food sources such as berry crops are
less available, and this additional food source
results in a higher carrying capacity of the middle
basin for brown bears. All of the radio-collared
brown bears that moved to the Prairie Creek area
had portions of their home ranges north of the
Susitna River, and therefore had to cross the river
en route to or from Prairie Creek.
Movements of brown bear in the early spring also
appeared to be related to el~vation and the avail-
ability of new plant growth (ADF&G 1982e). With
the exception of sows with cubs, it appeared that
most brown bear moved to lower elevations on or
near the Susitna River following emergence from
overwintering dens. This was attributed to the
relatively earlier melt-off of snow~ particularly
on south-facing slopes. and the subsequent
availability of overwintered berries and new plant
E-3-330
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4.2-Baseline Description
growth. Carcasses of wi nter-k i 11 ed u ngu 1 ates and
new-born calves in these areas also would provide
food for brown bears. Radio 1 ocat ions of brown
bears in the middle Susitna Basin during the
springs of 1980 and 1981 indicated that, excluding
sows with newborn cubs {which rema·ined at higher
elevations), 62 percent and 52 percent of the
radio-collared animals, respectively, moved to
areas on or adjacent to the Su sitna River (ADF&G
1982e). S. Miller (1982 pers. comm.) feels that
these figures are minirrum estimates, since spring
use of the impoundment zone by other bears may have
been missed because of infrequent monitoring.
However, since it was impossible to capture a
random sample of bears within the basin, these
figures most 1 ikely over-estimate use of the area
by the basin-wide population. Females with newborn
cubs remained at high elevations throughout the
year. Brown bears were at the lowest mean eleva-
tions during June to August {ADF&G 1982e).
Although some of the regional and elevational move-
ments of brown bears in the middle Susitna Basin
may be related to forage availability, these move-
ments may also be associated with brown bear preda-
tion of moose and caribou calves. Directional
movements by four radio-collared brown bears to and
from the calving grounds of the Nelchina caribou
herd suggest that brown bears may move to calving
areas primarily because of the availability of
calves (ADF&G 1982e).
-Denning
Brown bear dens in the middle Susitna Basin were on
moderately sloping southern exposures, and were
generally dug in gravelly soils either in tussock
or shrub habitats {ADF&G 1982e). (Use of vegeta-
tion types for denning is discussed below.) None
of the bears in this study reused den sites. Brown
bear den sites ranged in elevation from 2330-5151
feet {710-1570 ·m) with an average elevation of
4180 feet (1274 m).
Radio-collared brown bears in-the middle Susitna
Basin entered dens in early October 1980 and in
late September-early October 1981. !llring the
spring of 1981, most bears emerged from their dens
in late April-early May (ADF&G 1982e).
E-3-331
4.2-Baseline Description
(ii) Habitat Use
Brown bears in other areas of Alaska and northern
Canada utilize a wide range of vegetation corruruni-
ties. Habitat affinities of brown bear in the middle
Su sitna Basin were based on the predominant vegeta-
tion types in the vicinity of each relocation of the
radio-collared bears as determined from aerial obser-
vations. Brown bear use of spruce vegetation types,
which are concentrated around and in the proposed
impoundments, was highest in May and June (Table
E.3.107) (ADF&G 1982e). Bears tended to move to
shrublands at higher elevations later in the summer
{58 percent of the observations in September were in
shrubland, whereas only 28 percent of the May sight-
ings were in this type) (ADF&G 1982e).
Comparisons of the use of vegetation types by brown
bears during the spring and the remaining portion of
the year indicated that brown bears used spruce for-
ests significantly more often during the spring than
during other times of the year (ADF&G 1982e). As
discussed earlier, sows with newborn cubs fended to
remain at higher elevations; of 68 observations of
sows with cubs, only 1 occurred in spruce habitat.
Shrublands were most commonly used by sows with cubs
(49 percent of the observations) followed by 11 0ther 11
habitats (35 percent), tundra {10 percent), and
riparian communities {4 percent).
-Food Habits
Studies of the feeding habits of brown bears indi-
cate that the species is omnivorous, feeding on a
wide range of plants and animals. Although plant
material may commonly comprise a major portion of
the diet, it appears that brown bears prefer high-
protein animal food (Craighead and Mitchell 1982).
From dietary studies of brown bears in interior
Yukon {Pearson 1976) and in Yellowstone National
Park (Craighead and Sumner 1980), it appears that
brown bears most commonly utilize graminoids and
forbs during the spring and early summer. As
berries and fruits become more available, these
also are incorporated into the diet. Brown bears
will eat carrion, if available, and may also kill
ungulates or other large marrunals. Small rodents
such as ground squirrels are most often consumed
during the 1 ate summer.
E-3-332
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4.2 -Baseline Description
As discussed earlier, brown bear are attracted to
both natural and artificial food sources, particu-
larly if food is abu-ndant and read"ily available.
Some brown bear po~l at ions traditionally form
aggregations to feed on salmon during the major
fish runs (Stornorov and Stokes 1972).
Information on the di~ts of brown bear in the
middle Susitna Basin is limited. Overwintering
berries and new green shoots of grasses and forbs
are consumed during the early spring. Winter-
killed ungulates as well as moose and caribou
calves also are eaten. King salmon likely comprise
much of the diet of bears moving to Prairie Creek
during the salmon run in July and August. Berries
such as Vaccinium spp. are 1 ikely consumed thr.ough-
out· the 1 ate summer and fa 11 period.
One of the most notable results of the brown bear
studies in the middle Susitna Basin is recognition
of the importance of brown bear predation to moose
recruitment. Ballard et al. (1981a) found that of
123 radio-tagged moose calves, 55 percent had died
of natural causes by November (following their
birth) and that 79 percent of all natural mortali-
ties were caused by brown bear predation. Reloca-
tions of 23 radio-collared brown bears that were
intensively monitored (twice per day) during the
spring of 1978, showed that 14 of the 23 bears
reg.1l arly relocated were observed at 1 east once on
a moose calf kill (Ballard et al. 1981a, Spraker et
al. 1981). During the latter study, a total of 37
calf moose, 28 adult moose, 4 unidentified moose, 3
caribou, and 6 other species of mammals were killed
by brown bears, yielding a total of 1 kill/5.6 ob-
servation days {1 moose/6.3 observation days). The
lower kill rate of 1 kill/10.2 days given by ADF&G
(1982e) is probably an underestimate because of
less frequent monitoring of radio-collared animals
(compared to Ballard et al. 1981a) and is based on
only 3 moose calves, 2 adult moose, and 3 unidenti-
fied prey species. Although the full importance of
this highly preferred food source to brown bear is
not known, Craighead and Mitchell (1982) found
spring weight gains only in brown bear able to
secure ungulate calves or similar high protein
diets.
-Home Range
The average home range size of male brown bears in
the middle Susitna Basin is 195,200 {790 km2,
E-3-333
4.2-Baseline Descr}ption
n==14); for females it is 78,090 acres (316 km2,
n=19) (ADF&G 1982e).
Comparisons of the home range sizes of brown bears
in the middle Susitna Basin with brown bears in
other areas indicate that bears in the Susitna
Basin have relatively large home ranges (Table
E.3.108) {ADF&G 1982e). Only home ranges of bears
from northwestern Alaska (a relatively unproductive
population) were larger. On the basis of this in-
formation, ADF&G (1982e) suggested that home range
size and brown bear densities are inversely related
and that both are a function of the distribution
and abundance of food resources. The 1 arge home
ranges of brown bears in the Susitna Basin. there-
fore, may reflect relatively low productivity of
food items that are important to brown bears and/or
a patc'·,y distribution of important food items.
As discussed previously for moose. home range
analyses are useful in assessing the number of ani-
mals that may be affected by the proposed impound-
ments. ADF&G (1982e) examined the relationships
between the home ranges of radio-colla red brown
bear during 1980-1981 and three arbitrarily chosen
areas that included: (1) the proposed impoundment,
(2) a 1 mile (1.6 km) zone around the proposed
impoundments, and (3) a zone occupying areas 1 to 5
miles ( 1.6 to 8 km) from the proposed impound-
ments.
The mean ,overlap of the home ranges of 19 brown
bears with the impoundment was 5 percent (range of
0-25 percent), for the 1-mile (1.6 km) zone it was
15 percent {0-48 percent), and for the 5-mi l e (8
km) zone it was 52 percent (0-100 percent) (ADF&G
1982e). These figures under-represent the actual
use by brown bears of the area in and adjacent to
the impoundment area because the home range figures
used in calculating the percent overlap are the
total annual home ranges. Seasonal use by brown
bears, particularly during the spring. is more
intensive.
Analyses of the proximity of relocations to the
proposed impoundments similarly show that radio-
collared brown bears selectively use areas that are
close to the Susitna River~ particularly during the
spring period. Comparisons of the number of bear
relocations in the impoundment areas, as well as in
the two "impact" zones discussed earlier, indicate
that use in the actual impoundment area was greater
E-3-334
p-,;--
-
4.2-Baseline Description
than expected during a 11 periods (a 1 most 4 times
greater during the spring) and that use of the
outermost zone (1 to 5 miles, 1.6 to 8 km), was
less than expected (ADF&G 1982e). However, these
analyses probably overestimate use of the impound-
ment zone by the middle basin population because of
sampling bias.
(iii) Pop .. llation Characteristics
-Pof.!Jlation Size
Brown bear population estimates are extremely dif-
ficult and expensive to obtain because of the
wide-ranging behavior of most individuals and their
use of some habitats where sightabi 1 ity is poor.
Miller and Ballard (1980) used a Lincoln Index to
calculate a rough density estimate of 1 bear/10,112
to 15,296 acres (1 bear/41-62 km2) in the Susitna
River headwaters during 1979. This estimate sug-
gests that brown bear densities are intermediate
between densities in southern and coastal Alaska
and the Brooks Range (Table E.3.109). Based on an
estimate of 1 bear/10,112 acres (1 bear/41 km2),
the brown bear study area (an area of 2,093,678
acres [8473 kin2]) that includes the middle basin
(see ADF&G 1982e) would have a population of
approximately 206, brown bears. It was the opinion
of ADF&G ( 1982e) that brown bear densities in this
area were likely to be higher than this estimate.
-Population Structure
Information on the sex and age structure of the
brown bear population in the middle Susitna Basin
was available from GMU 13 harvest data during 1970
to 1980, the 1979 study of brown bears in the
middle Susitna and Nelchina river basins (Miller
and Ballard 19,80), and from capture data from the
recent brown bear study (ADF&G 1982e) (Table
E.3.110.
The age composition of brown bears captured in the
middle Susitna Basin duri[lg 1980-1981 was 19.6 per-
cent cubs, 11.8 percent yearlings, 12.1 percent
two-year olds, 15.7 percent three-and four-year
olds, and 39.2 percent adults. The moderately high
percentages of young animals in the Susitna brown
bear population suggest that the population is
young and productive.
E-3-335
4.2-Baseline Description
-Productivity
The mean litter size for brown bears in the middle
Susitna Basin was 2.3 (range of 1 to 3), based on
nine 1 itters of newborn cubs observed with radio-
collared females since 1978 (ADF&G 1982e). The
mean litter size for the basin is comparable to
those in highly productive brown bear populations
on Kodiak Island and on the Alaska Peninsula, and
is higher than litter sizes in the relatively un-
productive Brooks Range brown bears (Table
E.3.111).
Of 10 cubs in 5 known · 1 itters produced in the
middle Susitna Basin during 1981, 3 {in 3 litters)
were lost during the summer of 1981 (ADF&G 1982e).
One of these losses may have been capture-related.
Tait (1980) has suggested that abandonment of
1 itters of s·ingle cubs may be an adaptive strategy
for brown bears. Physical evidence (1 actation)
suggests that another bear may have had a litter in
1981, but cubs were never observed; they may have
been lost prior to the recapture of this bear
during summer 1981. In 1979, studies showed that
two cubs in a litter of 3 were lost as were 2 year-
1 ings or cubs in a another 1 itter of 3. No other
losses from yearling or 2-year-old litters were
observed, suggest·ing that offspring mortality is
concentrated on cub classes. Causes of cub losses
were not determined, but predation by male brown
bears was considered most probable (ADF&G 1982e).
Comparisons of the reproductive rates of brown
bears in the middle Susitna and Nelchina basins
with reproductive rates of other brown bear popula-
tions indicate that the Susitna-Nelchina Basins
support some of the most productive brown bear
populations in Alaska (Table E.3.112).
-Dispersal
ADF&G (1982e) believed that dispersal of sub-adult
brown bears, both to and from the study area, was
probably common. Several instances of dispersal by
radio-collared brown bears were recorded. One
male, originally tagged as a 2-year-ol d ·in 1978 on
the Susitna River north of the Denali Highway, was
recaptured and radio-collared near Clarence Creek
on the Su sitna River. Another 2-year-old male was
E-3-336
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4.2-Baseline Description
(e)
captured near Deadman Creek during the sprinQ of
1981 and mvoed downstream (54.9 miles, 88.5 km) to
the vicinity of Moose Creek. During the fall, the
same animal moved back to the vicinity of Sherman
and Curry. The importance of dispersal in
maintaining brown bear population levels in the
Susitna River basin and in adjacent river drainages
i s not known.
-Sport Harvest
ADF&G harvest data for brown bear in GMU 13 are
presented in Table E.3.113 (ADF&G 1982e). From
1973-1980, harvests averaged 64/year (44-84). The
mean age of brown bears taken during the period
1973-1980 was 6.5 years (6.3 for males and 6.8 for
females)-This relatively young age suggests that
many GMU 13 hunters are not selecting large trophy
bears. Of 656 bears that have been harvested and
aged in GMU 13 during the period 1970-1980, 10
percent were yearlings, 29 percent were 2-years-old
or less, 41 percent were 3-years-old or less, and
52 percent were 4-years-old or less (ADF&G 1982e).
In recent years, sport hunters have applied pres-
sure to extend brown bear seasons and bag limits in
GMU 13. This pressure has largely resulted from
research showing that brown bears are a major pre-
dator on moose calves (Ballard et al. 1980, 1981a).
In addition, Miller and Ballard {1980) suggest that
there may be a harvestable surplus of brown bears
in GMU 13.
Black Bear
All site-specific information on black bear populations in
the Su sitna Basin was obtai ned from the recent study by
ADF&G (1982e) during 1980-1982. Most of the data for 1981-
82 was for the middle Susitna Basin (upstream from the Devil
Canyon damsite), but the studies now underw(ly are also
focusing on bears downstream from Devil Canyon.
( i) Distribution
Black bears are the most common and widely distribu-
ted of the three bear species in North America. They
occur in most areas of Alaska as far north as the
Brooks Range. Black bears are highly adaptable and
are able to utilize a wide variety of habitats. Like
brown bears, they are omnivores and their ranges and
diet respond to regional and temporal changes in food
availability. Prime black bear habitat can be
E-3-337
4.2-Baseline Description
generally characterized by relatively inaccessible
forested terrain, thick understory vegetation, and
abundant sources of plant foods such as succulent
herbs and forbs, berries, and fruits (Pelton 1982).
Black bears appear to be moderately abundant in the
middle Susitna Basin. However, because of the limi-
ted distribution of suitable habitats, black bears
generally occur only in a narrow fringe of forested
habitat along the Susitna River.
-Seasonal Movements
Based on relocations of 53 radio-tagged black bears
during 1980-81, ADF&G (1982e) described the prob-
able seasonal movements of black bears in the
middle Susitna Basin as follows. In years of nor-
mal or abundant berry crops, many bears move in
late summer, to somewhat higher country adjacent to
the spruce habitats along the river, returning to
their spring and early summer home ranges near the
river to den. Most of these late summer movements
are upstream (east) and in a northerly direction
(ADF&G 1982e). In years of subnormal berry crops,
most individuals make more extensive movements,
moving 1 ong distances upstream or downstream in
search of acceptable foraging areas or areas where
salmon are available. These movements occur
primarily along the main Susitna River, indicating
that it is a main transportation corridor& Most
individuals making these extensive movements return
to their former home ranges, but some do not. In
late summer and fall, particularly during poor
berry years, these extensive movements of black
bears may bring them in close contact with brown
bears, possibly resulting in increased mortality of
black bears through inter-specific predation (ADF&G
1982e).
Females with newborn cubs are exceptions to this
general pattern of seasonal movements. Fema1 es
with cubs make less extensive movements than other
bears regardless of the berry crop.
-Denning
Distributions of den sites of black bears in the
Susitna Basin indicate that dens occur most common-
ly in steep terrain along the main Susitna River
and its tributaries (ADF&G 1982e). However, the
band of acceptable denning habitat appears to
E-3-338
.....
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-
4.2-Baseline Description
( i i)
become narrower and more confined in upstream areas
where dens are restricted to the immediate vicinity
of the Su sitn River.
Black bear dens in the Susitna basin were generally
located on moderately sloping hillsides; the mean
slope of 15 dens located during 1980-1981 was 36°
(range of 18°-53°). Half of the dens were located
on south-facing slopes, and the remainder were on
east-to north-facing slopes.
Black bears in the middle Susitna Basin generally
denned at elevations between 1499 feet (457 m) and
2500 feet (762 m). The average elevation of 16
dens between Tsu sen a Creek and Devil Canyon was
2178 feet (664 m) (range 1400-4340 feet,
427-1323 m). The average elevation of 13 dens in
the vicinity of the proposed Watana impoundment was
2179 feet (664 m) (range 1801-2749 feet,
549-838 m). Two black bears denned downstream from
the Devil Canyon site during 1981.
Of the 14 dens located during 1980-1981, 8 were in
natural cavities and 6 were excavated. All of the
dens in natural cavities and 1 of the excavated
dens had been used prior to the winter of 1980-
1981, and 4 of the dens were used again by radio-
collared bears during the winter of 1981-1982. In
contrast, b 1 ack bears on the Kenai Peni nsu 1 a were
rarely found to reuse dens during successive years
(Schwartz and Franzmann 1981). ADF&G (1982e)
suggest that the relatively high reuse of dens by
black bears in the Susitna Basin may indicate a
scarcity of acceptable den sites and/or habituation
to specific sites •.
Radio-collared black bears in the middle Susitna
Basin entered dens in mid-September to mid-October
1980 and exited dens in early April to mid-May
1981. During. the fall of 1981, black bears entered
dens about 2 weeks 2arlier than in the fall 1980,
probably as a result of the 1981 berry crop failure
(ADF&G 1982e).
Habitat Use
Habitat use by black bears in the middle Susitna
Basin appears to be similar to general use patterns
reported elsewhere in North America, where black
bears most commonly inhabit forested areas with dense
E-3-339
4.2-Baseline Description
understory vegetation (Jonkel and Cowan 1971, Fuller
and Keith 1980). Of 908 aerial observations of 53
bears in the Susitna Basin, black bears were most
often located in shrubland (42.7 percent of observa-
tions) and spruce (39.4 percent) habitats (Table
E.3.114) (ADF&G 1982e). Use of spruce habitats
remained high throughout the year but was IT1Jch less
prevalent during the summer months. IA.tring August,
black bears were often present in shrubland habitats
adjacent to the spruce forests. This use of shrub-
1 and areas was thought to be related to seasonal
increases in the avail abi 1 ity of ripening berries
(ADF&G 1982e). Use of spruce habitats appeared to
differ among male and female bears; of 126 locations
of female bears during the summer period, 43 percent
occurred in spruce habitats, whereas of 125 locations
of males, only 30 percent occurred in spruce
habitats.
An examination of habitat use by black bears within
the proposed impoundment area for the Watana dam
showed that deciduous forests and shrubl ands were
used significantly more often than expected. Other
habitat types were used approximately in proportion
to their availability. In the deciduous forest cover
type, closed birch and open birch forests accounted
for all of the locations. Similar habitat associa-
tions were observed in black bear poJXJlations in
northern Alberta (Fuller and Keith 1980).
-Food Habits
Throughout their range in North America, black
bears consume primarily grasses and forbs during
the spring, soft mast (fruits and berries) of trees
and shrubs-during the summer, and a mixture of hard
and soft mast during the fall. Only a small por-
tion of black bear diets typically consist of ani-
mal matter and then primarily in the form of
insects or carrion. Spring is generally a period
of food scarcity and bears may often subsist on
remaining fat reserves (Rogers 1976). Preferred
high-quality foods of black bears are generally
more abundant during the summer, and animals
develop most of their fat reserves during this
period.
Little site-specific information is available on
the food habits of black bears in the Susitna
Basin. As discussed earlier, berry crops are an
E-3-340
-
4.2-Baseline ~escription
important component of the 1 ate summer diet, and
movement of black bears into shrubland habitat is
thought to be related to the availability of
berries in these areas. Although plant foods may
constitute the staple diet during most of the year,
black bears may also prey on moose calves during
the spring (ADF&G 1982e). Black bear predation on
moose calves is prevalent on the Kenai Pennisula,
where 70 percent of the known predator-caused
deaths were attributed to black bears (Franzmann et
a 1. 1980). Ill ring intensive radio-monitoring of
black bears during May 22-June 22, 1981, one male
bear was observed on one calf moose kill and one
adult caribou kill. Later in July, the same bear
was observed on a kill of a radio-collared adult
moose. It is not known if the bear had ki 11 ed
these animals or if it was scavenging kills of
another predator.
-Home Range
During 1980, the·mean home range size of 20 black
bears in the middle Su sitna Basin was 7616 acres
{31 km2), 3968 acres (16 km2) for 10 females
and 11,392 acres {46 km2) for 10 males. lllring
1981, however, the average home range size was
53,888 acres {218 km2): 49,408 acres {200 km2)
for 11 females and 57,792 acres (234 km2)for 12
males. Although the large increase in home range
size between years may be partly related to the
greater number of observations of bears during
1981, ADF&G ( 1982e) suggests that the 1 arger home
ranges may reflect the relatively poor berry crop
during 1981 and the subsequent need for black bears
to move greater distances to find suitable foraging
areas. The observation of black bears north of the
Denali Highway (a rare occurrence) during 1981
supports the suggestion that black bears made
atypically long movements during the summer of 1981
(ADF&G 1982e). Comparisons of home range sizes of
black bears on the Kenai Peninsula (4096 acres
[16.7 km2] for females and 24,192 acres [98 km2
for males) (Schwartz and Franzmann 1981) with those
of b 1 ack bears in the Su sitna area suggest that
home ranges of black bears in the middle basin are
1 arge.
E-3-341
4.2-Baseline Description
The proximity of black bear home ranges to the pro-
posed impoundments suggest that black bear di stri-
butions are closely associated with lower elevation
habitats along the Susitna River. ADF&G (1982e)
delineated two arbitrarily chosen zones around the
proposed impoundment areas (one included all areas
within 1 mile (1.6 km) of the impoundments and the
other included all areas 1-5 miles (1.6-8.0 km)
from the impoundments) to assess the potentia 1
effects of the impoundments and associated develop-
ment on black bear populations. The mean overlap
of 27 black bear home ranges with the impoundment
areas was 14 percent (0-45 percent). Overlap in
the two adjacent zones was 50 percent {0-100 per-
cent) and 122 percent (56-195 percent) for the 1
mile {1.6 km) and the 1-5 mile {1.6-8.0 km) zones,
respectively.
(iii) Population Characteristics
-Population Size
ADF&G (unpublished data) attempted a black bear
census in August 1982 using radio-collared bears
and the Lincoln Index method. The study area in-
cluded all black bear habitat in the middle basin
east of High Lake; areas west of High Lake were not
included because thick vegetation hindered sight-
ability. During the survey flights, 38 black bears
were sighted of which 9 were marked. The popul a-
t ion was known to contain at least 21 marked bears,
and thus an estimate of 90 bears (95 percent CI =
50-170) was derived. S. Miller (1982 pers. comm.)
felt that this estimate was too low, and the tech-
nique will be repeated in spring of 1983.
Productivity
Black bear populations in the middle Susitna
Basin appear to be productive and healthy (ADF&G
1982e). This suggests that habitat is adequate,
even if limited in extent.
Eight 1 itters with a total of 16 cubs were ob-
served with radio-collared females during 1980
and 1981 (ADF&G 1982e). Five of these 1 itters
wer:: not observed u nt i 1 June -August and may
have experienced some losses by this time. Be-
cause of this bias, the observed litter size of
2.0 cubs/litter may be a slight underestimate.
The observed litter size for 7 litters of
yearling black bears was 1.9.
E-3-342
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4.2-Baseline Description
Litter sizes in the Su sitna Basin appear to be
similar to those reported· for 1 itters in other
parts of North America. The mean litter size for
black bears on the Kenai Peninsula was 1.9 cubs/
litter, based on radio-collared animals (Schwartz
and Franzmann 1981). Erickson and Nellor {1964)
reported an average litter size of 2.15 for black
bears in Michigan and 2.0 for Alaska (the exact
locale was not identified). Jonkel and Cowan
(1971) documented 1 itter sizes of 1.5-1.8 cubs/
litter for a relatively unproductive black bear
population in Montana over a several-year
period.
Although cub production appears to be quite high
in the SUsitna. Basin, cub loss also is high •
Based on only 4 litters that were observed prior
to June 1981, 4 of 9 ( 44 percent) cubs were 1 ost.
No losses of ~ubs from litters were observed on
the Kenai Peninsula (Schwartz and Franzmann
1981). The high rates of cub loss in the Susitna
Basin are believed to be related to the vulner-
ability of cubs to predation by brown bears and
to the relatively high black bear densities (and
intra-specific competition for suitable habi-
tats) {ADF&G 1982e).
ADF&G (1982e) suggests, on the basis of available
productivity indices, that the Su sitna
poPJlations are not as productive as black bear
populations on the Kenai Peninsula. This was
based primarily on the older age of reproductive
maturity in the Susitna Basin and the high rate
of cub loss.
-Dispersal
Dispersal of black bears from the middle SUsitna
Basin may contribute to bear poj)Jlations in adja-
cent areas. Dispersal of bears into the Susitna
Basin appears less likely, however, because of the
apparently saturated· nature of black bear habitat
along the SU sitna River (ADF&G 1982e). Several
instances of dispersal from the study area have
been ~ocumented. One sub-adult male was captured
at Clark Creek and was later shot near Hurricane on
the Parks Highway. A 4-year old male was captured
north of the Susitna River and was later shot in an
area 44 miles {72 km) to the south. Three adult
black bears moved downstream from the middle
E-3-343
4.2-Baseline Description
(f) Wolf
Susitna Valley to areas downstream from the Devil
Canyon damsite. Two of these bears denned in the
downstream areas.
-Sport Harvest
Based on Alaska Department of Fish and Game records
for the 1973-1980 period, black bear harvests for
GMU 13 averaged 66/year (range 45-85) during a 365
day season with a bag 1 imit of 3 bears (cubs and
females with cubs excluded from legal bag limit)
(Table E .3.115) (ADF&G 1982e). Males constituted
74 percent of spring harvests and 65 percent of
fall harvests. Most of the harvest (74 percent)
occurred in the fall season when bears were taken
incidental to moose or caribou hunts.
The current harvest is well below the sustainable
harvest level. At present, it appears that few
hunters sufficiently prize black bear meat or pelts
from GMU 13 to charter an aircraft to hunt away
from the road system; only 35 percent of the
hunters taking black bear during 1973-1980 recorded
aircraft as their primary means of transportation
(Table E.3.115). However, it is probable that the
increasingly restrictive seasons and conditions for
moose and caribou hunting in GMU 13 will result in
increased black bear hunting in this area, espe-
cially as more hunters become aware of the exi s-
tence of substantial black bear pop..~lations in the
unit.
Recorded black bear harvests in the Susitna study
area during 1973-1980 averaged 8/year (a range of
1-15). In general, black bear harvests have been
increasing in recent years with the largest recor-
ded annual take occurring in 1980. The largest
harvests have occurred in the downstream region of
the Susitna River between the Indian and Talkeetna
rivers, the only portion of the study area current-
ly accessible by river boat or highway vehicle.
Wolves in GMU 13 have been the focus of many studies and a
subject of controversy for over 30 years (Ba 11 ard 1981).
The history of GMU 13 wolves between 1957-1968 is summarized
by Rausch (1969). From 1948-1953, poisoning and aerial
shooting by the federal government reduced wolf pop.~l at ions
to low levels. By 1953, only 12 wolves were estimated to
E-3-344
r-o--
4.2-Baseline Description
remain in the basin. The pop.~lation expanded to a peak
number of 400-450 by 1965 after federal predator control
efforts were curtailed (Rausch 1969). Moose pop.~lations
declined to low levels in the area, stimulating a series of
predator-prey interaction investigations beginning in 1975
(Stephenson 1978, Ballard and Spraker 1979, Ballard and
Taylor 1980, Ballard et al. 1980). Wolf control efforts
were renewed in 1976-1978, but by 1980, the wolf pop.~lation
had returned to pre-control levels (Ballard 1981). Recent
data on wolf distribution, habitat use, pop.~lation charac-
teristics, and detailed histories of individual wolves and
their packs are provided by ADF&G (1982f).
(i) Distribution
At least.19 wolf packs were known or suspected to be
utilizing the SUsitna Basin in 1980-1981 (Figure
E.3.98). At 1 east 6 and possibly 7 of these packs
occur adjacent to the Susitna impoundment.
Individual wolf packs have established territories
which, as indicated in Figure E.3.98, overlap little
with adjacent packs (ADF&G 1982f). However, because
of the large harvest of wolves in this area, packs
are periodically eliminated, and areas with no wolves
exist for varying periods of time until new packs are
formed by animals dispersing from adjacent areas.
ADF&G ( 1982f) provided detailed hi stories of pack
formation, membership changes, and disintegration for
. 6 packs, beginning as early as 1977. These data
indicate that pack territories appear to be more
stable than membership (i.e., that a pack is defined
by the area it defends rather than its size or
individual members). This may be the direct result
of the destab·ilizing influence of extended heavy
hunting and trapping and the removal of key indivi-
duals from pack structure.
Dur·ing the summer, activities of packs conta·ining
breeding adults are centered on den and rendezvous
sites, the latter being above-ground sites where the
pups play and are fed from the time they are about 2
months old. Figure E.3.99 shows the locations of
known dens and rendezvous sites in the Susitna Basin.
Dens are generally but not always roughly centered
within a pack • s territory, and each is frequently
used for more than 1 year. Average distance between
35 dens in the Su sitna and adjacent areas was com-
puted to be 28.1 miles (45.3 km) (ADF&G 1982f), a
distance that compares well with 24.9 miles (40.2 km)
observed in the Brooks Range of Alaska (Stephenson
and Johnson 1973).
E-3-345
4.2-Baseline Description
(ii) Habitat Use
Habitat types used by wolves vary widely (Paradiso
and Nowak 1982) and in any particular area are
probably determined largely by the habitat of their
major prey. In the Susitna Basin~ detailed data on
habitat use were collected for the Watana pack
between April 1980 and November 1981. This pack used
a wide variety of habitats but was most frequently
encountered in shrub and spruce habitat types (ADF&G
1982f).
Wolf dens in the Susitna area are mostly old red fox
dens taken over and dug out by wo1ves. The majority
are located on slightly elevated sandy areas provid-
ing good drainage. Entrance holes face predominantly
south or east. Both dens and rendezvous sites have
been found in a variety of habitats. Over story trees
or shrubs at den sites include spruce, aspen, balsam
poplar, paper birch, and willow in densities ranging
from 90 percent cover to very sparse (ADF&G 1982f).
-Food Habits
Food habits of wolves in the Su sitna area were
studied by both direct observation of kills and
analysis of scats collected at den and rendezvous
sites (ADF&G 1982f). The former method covers all
seasons, whereas the 1 atter provides only summer
food habits.
During 1980 and 1981~ 6 radio-call ared wolf packs
were observed on 83 kills. Moose comprised 57
percent of the kills, whereas caribou comprised 33
percent. Other prey. such as snowshoe hare,
beaver, muskrat. and other small mammals made up
the remaining percentage of kills. Calves accoun-
ted for 51 percent of the moose kills, and com-
prised 7 percent of kills of caribou.
Tab1e E.3.116 summarizes wolf summer food habits as
determined from analyses of scats collected at den
and rendezvous sites during 1980 and 1981. Moose
of all ages were the most important summer food
items during both years of study. However, ADF&G
(1982f) suspected that the importance of calf moose
was probably overemphasized by these data.
E-3-346
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r
i
4.2 -Baseline Description
Predation rates in the Su sitna area have been
estimated to average one kill per pack every 5 days
(ADF&G 1982f). Rates vary somewhat with pack size
(Ballard et al. 1981b) but do not appear to vary
seasonally (ADF&G 1982f) as has been suggested for
some areas (Peterson 1980).
Studies of wolf food habits in the eastern Susitna
Basin and adjacent areas since 1975 have suggested
that moose are the single most important food item
(Ballard et al. 1981b). Adult moose are taken se-
lectively from August through December~ while short
and long yearling moose (moose that are a few
months younger or older than 1 year) comprise a
disproportionate number of January to July kills.
Wolves take relatively healthy moose in winter.
Ballard et ·al. (1981b) found that during severe
winters all ages of adult moose were taken in pro-
portion to their representation in the population~
but in average and mild winters disproportionate
numbers of older adults were taken •
Caribou have comprised between 4 and 30 percent of
wolf kills from 1975 to 1981. Excluding 1978, when
the main body of the Nelchina caribou herd wintered
in the Wrangell Mountains and thus was largely un-
available during winter, the importance of caribou
in the diet of Susitna Basin wolves appears to have
increased. (Wolf diets averaged 18 percent caribou
for 1975 through 1977 in comparison to 26 percent
caribou for 1979 through 1981). Some of the annual
difference in percentage of occurrence of caribou
c·oul d be att ri bu ted to the difference in the 1 oca-
tions of wolf packs studied during these time per-
iod-s in relation to distribution of caribou. Cari-
bou distribution, however, is probably related to
herd size (Skoog 1968). The Nelchina herd reached
a record low of approximately 7500 in 1972. Since
that time, the population has increased to over
20,000. It is suspected that the increase in the
caribou population generally has made caribou more
available to wolves throughout the eastern Susitna
Basin and adjacent areas. If true~ this pattern
would suggest that if the herd grows even larger,
caribou wi 11 become more important as wo 1 f prey.
Assuming wolf poJXJlations in this -area increase
slightly or remain stable, a larger caribou popula-
tion may have some positive benefits for moose, in
that a larger percentage of the wolf kills may com-
prise caribou~ relieving the moose poJXJlation of
some predation mortality.
E-3-347
4.2-Baseline Description
-Home Range
Each of the six wolf packs studied by ADF&G {1982f}
in the Susitna Basin maintained the same home range
during the period that the pack existed as a stable
unit. Wolf packs in this area occasionally defend
their territories against other wolves, although
i ntru si ons into territories often occur when the
home pack is not using that portion of the area.
Observed pack home ranges varied in size from
232,960 acres {943 km2) to 621,440 acres {2514
km2) and averaged 348,800 acres {1412 km2).
(iii) PoPJ 1 at ion Characteristics
Wolves in the Susitna Basin are heavily hunted and
were also subject to an intensive control effort by
the Alaska Department of Fish and Game from 1975 to
1978. This control was an attempt to mani PJ 1 ate
moose numbers experimentally by reducing predation.
Whether the wolf pop..tlation was at a low level in
1980-1981, when detailed studies related to the
Susitna project began, is unknown. The pop..~lation in
the Susitna Basin in 1980-1981 ranged from about 40
in spring after the hunting/ trapping season to about
75 in fall when the pups join the hunting adults
(Table E.3.117}.
Although there has been ITllCh speculation, there is
1 ittl e agreement on the factors that control _wolf
populations. Van Ballenberghe et al. {1975} believed
that pack density, prey abundance, and degree of
exploitation varied so ITI.lCh among pop..~lations that
the combination of factors controlling one population
might be quite different from those controlling
another. In the Susitna Basin human exploitation is
quite clearly the most important factor. The is no
bag l·imit on harvest of wolves in GMU 13 and season
is open from August 10 to April 30. In 1981 and
1982, almost half the fall population was removed
through legal and illegal winter hunting. Including
wolves taken during the wolf control program from
1975 to 1978, the average yearly harvest from the
Su sitna Basin and areas immediately adjacent (Game
Management Units 13A, 13B, and 13E) averaged 38 and
ranged from 26 to 68. Additional large numbers of
wolves were taken illegally in each year (ADF&G
1982f).
E-3-348
-
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4.2 -Baseline Description
{g)
Although there are few specific data, the maintenance
of these high levels of harvest suggest high produc-
tivity in the pop.tlation. ADF&G {1982f) does not
report average litter size for the packs they
studied, but their remarks suggest that 6-8 pups were
produced yearly by each pack. High productivity,
both in terms of proportion of adult females that
whelp and litter size, has been demonstrated in other
expl cited pop..~l at ions both in Alaska and elsewhere
{Rausch 1967, Van Ballenberghe et al. 1975).
The large numbers of PJPS produced each year results
in a large pop..~lation of young wolves likely to dis-
perse to other areas. ADF&G {1982f) gives numerous
examples of radio-collared wolves that moved from one
pack to ano:ther within the basin; wolves that esta-
blished new packs in vacant areas; and wolves that
left the basin entirely. Dispersal of individuals is
often preceded by forays away from the pack home
range and may be precipitated by death of most of the
other pack members through sport hunting or packing.
Wolverine
The wolverine remains one of the most poorly known of the
larger carnivores, and few scientists have attempted to
study wolverines in their natural habitat. Van Zyll de Jong
{1975) states that the reason for this is that the species
is uncommon, highly mobile, and restricted to the more
remote and inaccessible parts of the country. Most
wolverine studies in North America have reported on the
species' breeding biology and other information obta·ined
from carcasses {reviewed by Rausch and Pearson 1972).
Recent advances in radio-telemetry have resulted in studies
of wolverine movements, habitat use, and home ranges in
northwestern Montana {Hornocker and Hash 1981), northwestern
Alaska {Magoun 1982), and in the middle Susitna Basin {ADF&G
1982g).
(i) Distribution and Habitat Use
Wolverines occur throughout the Su sitna Basin and
appear to show little preference for specific habitat
types {Figure E.3.100). The lack of use of specific
habitats is most 1 ikely related to the scavenging
lifestyle of this species which dictates seasonally
long movements, a relatively large home range, and a
E-3-349
4.2-Baseline Description
solitary existence (Hornocker and Hash 1981). Van
Zyll de Jong ( 1975) states that 11 the wolverine • s
niche explains the relative rareness of the species
in the comrru nity compared to the efficient hunters
among carnivores that act as providers [of carrion],
and it implies a direct relationship between the bio-
mass and turnover of large herbivore pop.Jlations and
the abundance and distribution of wolverines." The
wolverine's propensity for wandering far and wide~
which increases its chances of finding widely scat-
tered and immobile food, and its well-developed
food-caching behavior are probably also adaptations
to the scavenger role (Hornocker and Hash 1981).
Food availability appears to be the primary factor
determining movements and home range sizes of wolve-
rines (Hornocker and Hash 1981; ADF&G 1982g). Breed-
; ng activity also influences the seasonal movements
of males, and to a lesser extent~ of females (Hor-
nocker and Hash 1981; Magoun 1982). Temperature may
a 1 so influence movements; Hornocker and Hash ( 1981)
reported that, during the summer, wolverines of both
sexes moved to higher, cooler elevations and traveled
less during daylight hours. In the Susitna Basin,
ADF&G (1982g) reported that changes in wolverine dis-
tribution occurred throughout the year and that food
availability probably influenced these shifts. They
noted a pronounced movement in spring. summer, and
fall to higher elevations where arctic ground squir-
rels, marmots, and ground-nesting birds were abun-
dant. Food is most available in the spring and
summer, and wolverines consume a wide variety of food
at that time (see Wilson 1982). Krott (1959) found
carrion, small mammals~ insects and insect larvae,
eggs, and berries in the summer diet. Magoun (1982)
found microtines, ground squirrels, marmots, and
caribou in the spring and summer diets of wolverine
in northwestern Alaska.
Movements to lower elevations during winter are appa-
rently associated with the increased importance of
carrion in the diet during the winter months. During
winters of moderate-to-deep snow depths, the 1 ower
elevations along the Susitna River support high den-
sities of moose (ADF&G 1982a). Also, fewer birds and
small mammals are available at higher elevations dur-
ing the winter months (Kessel et al. 1982a). Winter
ground tracking indicated that wolverines were prey-
ing upon microtines, red squirrels, ground squirrels~
and spruce grouse in addition to carrion (ADF&G
1982g). Both red squirrels and spruce grouse are
E-3-350
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4.2 -Baseline Description
restricted to forested areas, and other small mammals
are also most abundant in coniferous and deciduous
forests.
The degree of territorialism exhibited by wolverines
in an area appears to be related to the turnover rate
of the wolverine population. Magoun (1982) found
that female wolverines in an essentially unharvested
population occupied exclusive home ranges that were
overlapped by those of males. She did not have
enough data to determine whether adu 1t male home
ranges overlapped. Hornocker and Hash (1981) stated
that wo 1 veri ne home ranges in northwestern Montana
overlapped between individuals of the same and oppo-
site sex and claimed that territorial defense was
essentially nonexistent. However, they were unable
to establish the 'residency status of individuals in
their population. Magoun ( 1982) reported that fe-
males with overlapping home ranges might be mother/
daughter combinations, and that young males which
have not yet dispersed might be overlapped by resi-
dent adult males. The data obtained on wolverines in
the Susitna Bas·in indicate that, except for some
overlap between adults and juveniles, individuals of
the same sex occupy mutually exclusive home ranges.
The overlap of ranges shown in Figure E.3.100 is
caused mostly by the mortality of some of these
animals during the studies. Hornocker and Hash
( 1981) suggested that trapping mortality in their
study area, while not excessive enough to reduce
population size, may have contributed to behavioral
instability within the population causing a breakdown
in the territorial system. They po·i nted out that
unexploited mountain lion populations showed a highly
refined system of territoriality, whereas exploited
populations were not territorial at all. Exclusive
use of home ranges by same-sex adult wolverines in
the Susitna Basin and northwestern Alaska may~ there-
fore, be a reflection of relatively low trapping
mortality.
(ii) Population Characteristics
The home range data obtai ned from the Su sitna Basin
study and from other studies can· be used to estimate
the number of wo 1 veri nes present in the upper and
middle basins. Home range sizes of male wolverines
will be used in these ca 1 cu 1 ati ons, s i nee more data
are available for males than for females. The
average home range size for 5 adult males located at
least 5 times was 101,760 acres {413 km2), ranging
from 34,560 to 154,880 acres (141 km2 to
E-3-351
4.2-Baseline Description
628 km2). These ranges were smaller than those
reported for males by Magoun (1982) (mean = 172,800
acres [700 km2]), but similar to the 104,320 acres
(422 km2) value found by Hornocker and Hash
(1981).
If we assume that wolverines in the 4,032,640 acre
(16,319 km2) middle and upper basins use all
habitat types (including rivers, lakes, rock and
ice), and further assume that adult male home ranges
are rrutually exclusive and contiguous, we arrive at
an estimate of 40 adult males in the middle and upper
basins. Reported sex ratios of wolverine kits taken
from dens and of fetuses do not differ from a 1: 1
ratio (Pulliainen 1968; Rausch and Pearson 1972);
therefore, an estimated 40 adult females also occur
in the area. According to Rausch and Pearson (1972),
the effective reproduction of wolverines is 2 kits/
1 itter. Hornocker and Hash ( 1981) believed that no
more than half of the females on their study area
were reproductively active in each of the five years
of their study, and only 53 percent of mature females
trapped in the Susitna basin were reproductively
active (ADF&G 1982g). About 40 kits are therefore
added to the basin's pop.Jlation each year, resulting
in a total summer estimate of 120 wolverines in the
basin. This converts to a density of 1 wolverine/
33,920 acres (1/136 km2). This compares with other
density estimates of 1/233 km2 in northwestern
Alaska (calculated from Magoun 1982); 1/65 km2 in
northwestern Montana (Hornocker and Hash 1981); 1/207
km2 in British Columbia (Quick 1953), and 1/200
km2 to 1/500 km2 in Scandinavia (Kratt 1959).
There are probably fewer than 120 wolverines in the
middle and upper basins, since it is unlikely that
wolverines use all areas; and emigration, immigra-
tion, and trapping and natural mortality probably
result in a smalle·r population size. Some juveniles
a 1 so occupy home ranges that do not overlap com-
pletely with those of adults.
Trapping is probably the main cause of mortality
among wolverines in the·susitna Basin. A total of 27
wolverines was harvested from this ar.ea during 1979-
1981; 20 during 1979-1980 and 7 during 1980-1981.
The low take during 1980-1981 was probably the result
of poor weather and snow conditions. Most trapping
occurs in the accessible periphery of the area.
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4.2-Baseline Description
(h) Be 1 u kha Wha 1 e
The belukha whale is a widespread arctic and subarctic cir-
cumpolar species that inhabits coasta 1 waters. In Alaskan
waters, two discrete stocks, a Cook Inlet-northern Gulf of
Alaska stock and a general Bering-Chukchi-Beaufort stock,
have been i dent i fi ed based on migration patterns, summer
concentration areas, and morphological differentiation
(Sergeant and Brodie 1969, Murray and Fay 1979, Gurevich
1980). No evidence exists to indicate interchange between
the Cook Inlet stock and the Bering Sea stock, and isolation
has been suggested based on morphological differentiation.
( i ) Distribution and Habitat Use
In winter, belukhas may be found in some of the ice-
free bays in southern Cook Inlet. Some individuals
apparently range across the northern Gulf of Alaska;
sightings of belukhas have been reported from
Shelikof Strait, Kodiak Island, and Yakutat Bay
(Fiscus et al. 1976; Calkins and Pitcher 1978;
Harrison and Hall 1978; Calkins 1979; and ADF&G
unp.Jblished data).
Be lu khas aggregate in groups of two to severa 1 hun-
dred individuals in spring and summer seasons. These
concentrations have been attributed to exploitation
of locally concentrated foods, such as anadromous
fish (Tarasevich 1960, Sergeant 1962). Belukha con-
centrations are also apparently associated with poly-
~amous breeding in April and May, with calving
{reported to occur in May through August in brackish
lagoons) and with the subsequent nursing of neonates
(Seaman and Burns 1981).
Most of the Cook Inlet pop.Jlation moves into upper
Cook Inlet in spring and remains there through rruch
of the summer. In spring and summer, concentrations
develop near mouths of streams and rivers in the
northern inlet. The largest concentrations occur
annually between the mouths of the Susitna and Beluga
rivers, sometimes ascending the rivers for several
miles. Various species of smelt and salmon, both
out-migrating smelt and returning adults, are the
most likely attractants in Cook Inlet rivers. There
has also been speculation that the mouth of the
Susitna River is a calving and nursing area for
belukhas.
E-3-353
4.2-Baseline Description
Aerial surveys were flown by ADF&G (unpublished data)
in upper Cook Inlet between May 17 and August 27,
1982, to identify the timing and magnitude of belukha
concentrations. Belukhas were concentrated in the
inlet south of the Su sitna River mouth from the date
of the first survey through 1 ate June or early July,
with a peak number of 300 animals counted on June 11.
As explained below, these counts may be one third to
one half the actual numbers present. By July 8, the
concentrations appeared to have broken up and only 7
whales were sighted in the Susitna to Beluga River
area.
No calves were sighted during these surveys, but
ADF&G attributed this to the low visibility in the
turbid waters of the upper inlet and indicates that
calves were likely to have been present when surveys
began on May 17.
(ii) Population Characteristics
Population estimates of the Cook Inlet stock from the
mid-1960s indicate 300-1000 belukhas in Cook Inlet,
with an estimate of 500 animals (Klinkhart 1966) most
accepted. More recent surveys support this estimate
(Calkins 1979; Calkins, unpublished data). ADF&G
(unpublished data) reported 300 belukhas from direct
counts ·in upper Cook Inlet on June 11, 1982, and
indicated that, because the turbid water obscured the
observers' vision, 2 to 3 times that many may have
been present but could not be observed.
4.2.2 -Furbearers
(a) Beaver
(i) Distribution and Habitat Use
Beavers are common and widely distributed throughout
much of North America. They occur throughout the
Su sitna River drainage, from Cook Inlet upstream
along the river, its tributaries, and ponds to eleva-
tions above 3281 feet (1000 m) (Gipson et al. 1982).
They are herbivorous and eat herbaceous and aquatic
vegetation as well as the bark, twigs, and stems of
trees and shrubs.
The Susitna River from Devil Canyon to the Delta
Islands was surveyed for beaver sign in the summer of
1980 by Gipson et al. ( 1982). Use of the river by
beavers increased progressively downstream from Devil
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4.2-Baseline Description
Canyon (Gipson et al. 1982). An overflight of the
river in the summer of 1981 and intensive surveys in
1982 confirmed this observation (Table E.3.118). No
beaver 1 odges, food caches, or dens were observed
within the active floodplain between the Tyone River
and Devil Canyon, but they do occur on some tribu-
taries and lakes in the middle bas·in. In summer
1982, Gipson et al. (un~XJblished data) surveyed the
river downstream from Devil Canyon using a river
boat, helicopter, and ground surveys to determine
beaver habitat preferences, lodge construction mater-
ials, and forage plants. Preferred food sources were
willow (particularly feltleaf willow), balsam poplar,
and paper birch. Alder was the primary material for
lodge construction but was rarely found eaten
(peeled). Peeled birch, poplar, and willow were also
used for construction.
The Su sitna River between the Deshka River and Por-
tage Creek was divided. into three sections on the
basis of river morphology and vegetation characteris-
tics: upper section from Talkeetna to Portage Creek,
middle section from Goose Creek to the Talkeetna
River, and lower section from the Deshka River to
Goose Creek. Each section was divided into linear
miles of floodplain parallel to the main channel, and
each samp 1 e unit was one of the mi 1 e sections from
the thalweg (the deepest part of the channel) to the
active floodpla·in boundary on one side. Beaver habi-
tat was classified into four categories for analysis
as described below. Although described in terms of
water type, habitat also included bank characteri s-
ties, water sources, and tree and shrub vegetation.
-Main Channel: Consisted of the major river thalweg
and assoc1ated land masses. Channels were charac-
terized by rocky and eroding banks with high velo-
city and high volume flows.
-Side Channel: Consisted of channels which split
off the main thalweg, yet carried large volumes of
water. Representative channels showed rocky banks
and silty flow with generally high velocity. Sub-
stantial amounts of erosion were often associated
with side channels.
-Sloughs: Lower volume and slower flow charac-
terized these channels. Silty banks with estab-
1 i shed vegetation were characteristic along with
reduced erosion. The water source was
E-3-355
4.2-Baseline Description
predominantly the Susitna with some clear-water
mixes. A number of sloughs may exist only at
normal or high water levels.
-Clear water: This habitat consisted of creeks,
river runoff, and seeps which were of non-Susitna
or filtered clear water. Slow to moderate flow,
s i 1 ty banks, and estab 1 i shed vegetation were
characteristic.
In all sections of the river, beaver were found to
prefer slow-moving side channels or sloughs, as well
as mouths of tributaries (see Table E.3.118). Such
sites increase progressively downstream as the river
channel becomes more braided. Beaver in the middle
and lower sections are reported by residents to use
bank lodges which have an underwater entrance and an
air vent under a large tree. If this is the case,
the "high activity" values in Table E.3.118 for these
sections are low, since there is no. detectable sign
for these types of dens that would have been
recorded.
Slough and Sadlier (1977) identified the major compo-
nents important to beavers as water depth, stability,
and flow rate and distance to suitable food species.
They found that the variables which correlated best
with beaver pojJJlation densities were low flow, low
gradient (low erosion potential), and banks contain-
ing a high percentage of food speci,es. Results of
the 1982 survey agree with their work as well as the
findings of Boyce (1974) and Hakala (1952), who
reported that beavers in Alaska favor lakes or slow-
moving streams bordered by subclimax stages of shrub
and mixed conifer-deciduous forests. The results
a 1 so agree with a study by Retzer ( 1955) who found
that beavers avoid large rivers· with narrow valleys
and high velocity flows.
(ii) Pop.Jlation Characteristics
Aerial surveys of food caches in the fall have been
shown to be an accurate method of determining the
number of active beaver colonies in an area (Hay
1958, Machida 1982). An aerial cache survey conduc-
ted by Gipson et al. (unjJJblished data) in 1982
revealed 14 beaver food caches in the active flood-
plain of the Susitna River between Portage Creek and
Talkeetna (0.26/mile [0.16 caches/km]). Each cache
is estimated to support five beavers (Boyce 1974), so
the population of that stretch of the river is
E-3-356
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4.2 -Baseline Description
{b)
estimated at 70 beavers. This is a low pop.~lation
density compared to a range of 0.56 -0.65/mile
{0.35-0.40 colonies/km) found elsewhere in Alaska
(Boyce 1974), but was expected to be 1 ow because of
the scarcity of side channels and sloughs with slow-
moving water along this reach of the river. Beaver
densities would be 111.1ch higher if beavers in nearby
ponds and tributaries were included, but these areas
are unlikely to be affected by the project and there-
fore were not sampled. Pop.~lation estimates were not
possible for the river south of Ta 1 keetna, because
high water levels had obscured or destroyed many of
the existing caches.
The 1982 survey also included Deadman Creek because
of its proximity to the proposed access road. The
density of beavers was 0.85/mile (0.53 active
lodges/km) along the middle portion of Deadman Creek
and was even higher in a marshy section of upper
Deadman Creek (Table E.3.119). An estimated 65
beavers currently occupy this creek.
Beaver pop.~l at ions are productive and can withstand
moderate trapping pressure. First breeding occurs at
age 2 or 3, and annual litters average 3 to 4 young
thereafter (Hill 1982). Young beavers disperse dur-
ing the summer of their third year, sometimes travel-
ing as far as 124 miles (200 km) to set up new lodges
(Hill 1982). Trapping for beaver has historically
been common along the Susit~a River below Devil
Canyon, along major tributaries, and arQund larger
lakes like Stephan Lake (Gipson et al. 1982).
Beavers in alpine areas have seldom been trapped be-
cause of the effort involved. These pop.~lations are
vu 1 nerab 1 e to en vi ronmenta 1 alteration and/ or over-
trapping because of their dependence on small,
isolated riparian habitats (Gipson et al. 1982).
rtlskrat
Muskrats are common and widely distributed throughout most
of North America. They occur throughout the Susitna River
drainage from Cook Inlet upstream along the river, its tri-
butaries, and ponds to elevations above 3281 feet (1000 m).
Muskrats are primarily herbivorous, with a diet that
includes pondweed and swamp horsetail (Perry 1982).
The middle Su sitna Basin was surveyed for 111.1 skrat sign in
the early spring of 1980 by Gipson et al. (1982). All lakes
within 3 miles (4.8 km) of the Susitna River were surveyed
by helicopter, from the confluence with the Osh~tna River to
E-3-357
4.2-Baseline Description
Gold Creek. MJskrat pushups were observed on 27 (26 per-
cent) of the 103 lakes surveyed (Table E.3.120). Most of
the 1 akes and ponds with rru skrat sign were above the river
valley, between 870 and 2840 feet (265 and 865 m) in eleva-
tion. Pop.1lations of rruskrats were also noted along slow-
flowing sections of larger creeks, particularly where lakes
drain into streams (Gipson et al. 1982).
A downstream survey of rruskrat use of Susitna River habitats
conducted by riverboat in the summer of 1980 indicated that
rru skrat numbers increase with distance from Devil Canyon
(Gipson et al. 1982). Suitable slow-water habitat in
sloughs and side channels increases in availability down-
stream from Ta 1 keetna. No sign of muskrat was noted on the
river between Devil Canyon and Talkeetna. Between Talkeetna
and Montana Creek, sign of muskrat was 1 imited to sloughs
and marshy areas near the mouths of feeder streams. Muskrat
sign was more commonly observed downstream from Montana
Creek where numerous side channels and sloughs occur (Gipson
et al. 1982).
Trapping for muskrats has historically been common along the
Susitna downstream from Devil Canyon, along major tributa-
ries, including Indian River and Portage Creek, and around
larger lakes, such as Stephan Lake. Muskrats in alpine
streams and 1 akes have seldom been trapped because of the
effort i nvo 1 ved.
(c) River Otter
Information concerning the distribution and abundance of
river otters in the middle Susitna Basin was obtained during
autumn aerial and winter ground surveys by Gipson et al.
(1982) (see Tables E.3.121, E.3.122 and E.3.123, and Figure
E.3.101). These data indicate that otters are common along
the Susitna, its tributaries to 3937 feet (1200 m) eleva-
tion, and around large lakes. This distribution is probably
related to the distribution of prey of otters, which
includes primarily fish and crustaceans (Ryder 1955, Knudson
and Hale 1968, Toweill 1974, Gilbert and Nancekivell 1982).
In November 1980, an unusual concentration of otter tracks
was found on the river ice within the proposed impoundment
areas (Gipson et al. 1982). The significance of this track
concentration is unclear, but it may represent upriver or
downriver movements of otters prior to freezeup. It is also
possible that the otters were concentrating along the river
to feed on grayling, which were migrating out of the tribu-
taries to overwinter in the Susitna.
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4.2-Baseline Description
(d)
(e)
Some otter trails were also observed in cross-country
travel, away from bodies of water. Such tracks have been
noted in other areas of south-central Alaska and may
represent dispersing sub-adults (Gipson et al. 1982). Local
trappers seldom take river otters because they are
relatively difficult to trap, and the pelt values have
usually not been high enough to justify the effort.
Mink
Mink are locally abundant in the middle basin along the
river, its major tributaries to 3937 feet elevation
( 1200 m), and a 1 ong 1 akeshores. Track counts from both air
and ground in fall 1980 (Tables E.3.121 and E.3.122) suggest
that mink are more abundant in the upper ~eaches (east of
Kosina Creek) of the Watana impoundment area than they are
elsewhere (Gipson et al. 1982). Two mink were radio-
collared in 1980, but no data wer~ obtained because one
animal slipped its collar and the other•s radio failed.
Food habits of mink vary among areas, depending on prey
availability. Small mammals and fish usually form the
majority of the diet, but crustaceans and birds may also be
eaten (Errington 1954, Wilson 1954, Korschgen 1958).
Muskrats may form a major portion of the diet where they are
available (Hamilton 1940, Sealander 1943).
Marten
Pine marten are common nocturnal mustelids found in spruce
forests throughout interior A 1 aska. Information presented
here is provided by Gipson et al. (1982) from 3 types of
data: (1) radio-telemetry studies of home range, habitat
use and activity patterns of 14 individuals from fall 1980
to fall 1981; (2) snow-tracking data on habitat use; (3)
analysis of food habits from scats; and (4) aerial
snow-track survey data on habitat use and relative density.
(i) Distribution
Aerial surveys of the Susitna River flown in November
1980 indicated that marten were present at 1 east as
far downstream as Portage Creek and as far upstream
as the Tyone River (Table E.3.121) (Gipson et al.
1982). They are locally abundant in the vicinity of
the proposed Devil Canyon and Watana impoundments.
E-3-359
Gipson et al. (1982) found that home ranges of
adult male marten were mutually exclusive but
overlapped those of other sex/age classes. Average
home ranges of 10 radio-collared adult males were
1,734 acres (7.02 km2). Female home ranges
averaged 915 acres (3.71 km2) (n=3), excluding
one animal with an unusually shaped home range.
BetY.een spring and autumn 1981, some marten home
ranges appeared to shift location and vary in size
periodically. Marten rarely swim across rivers or
large creeks, which often form partial home range
boundaries in the study area.
Home range sizes in the Sus i tna area are midway
between the figure of 3,136 acres (12. 8 km2) for
4 marten in Minnesota (Mech and Rogers 1977) and
1,024 acres (4.1 km2) for 5 marten in the Yukon
Territory (Archibald 1980). Differences in home
range sizes in different areas and seasons are
attr·ibutable to variability of food resources
(Lensink et al. 1955, Soutiere 1978).
An estimated density of 0. 0034 marten per acre
(0.847/krn2) was calculated from radiotelemetry
data on 10 adult male marten along the Susitna
River between Deadman and Watana Creeks (S. Buskirk
1982 pers. comm.). This estimate assumes a 1:1 sex
ratio, with male and female territories overlapping
and 65 percent juveniles in the population (a
figure derived from trapper harvest data in the
Yukon Territory by Archibald 1980).
Information from former and present trappers
indicates that marten continue to be economically
the most important furbearer in the vicinity of the
impoundment zones (Gipson et al. 1982).
(iii) Habitat Use
Track counts from a November 1980 aerial survey
indicate that marten are most numerous in coniferous
and mixed forest and woodland and habitats below
1,000 m (3,281 feet) elevation (Table E.3.121)
(Gipson et al. 1982). The highest track counts
occurred between Devil Creek and Vee Canyon (Table
E. 3. 121) .
E-3-360
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(f)
Marten resting sites were located below ground in
late autumn, winter, and early spring. In summer,
when soi 1 temperatures are 1 ower than air
temperatures, marten rest above ground. Summer
resting sites could not be characterized because of
the escape response of marten above ground.
Thirty-one of 37 wi~tter resting sites (83 percent)
were in red squirrel middens or nests. All were in
forest or woodland vegetation types.
-Food Habits
The diet of marten shows some seasonal variation,
but microtine rodents are the primary prey at all
times of the year in interior Alaska (Lensink et
al. 1955). Microtines had an 88.8 percent frequen-
cy of o·ccu rrence in scats from the middle Su sitna
Basin (S. Buskirk 1982 pers. corrvn.) (Table
E.3.124). Plant foods, such as bog blueberries,
crowberries, mountain cranberries, and rose hips,
are consumed most frequently in autumn, and atta·i n
an average frequency of occurrence of 23.3 percent.
Bird remains were present in 9. 6 percent of scats,
most frequently in winter, and squirrels occurred
in 6.8 percent, most frequently in spring.
Red Fox
Red foxes and their sign have been observed throughout the
middle Su sitna Basin, including the proposed Devi 1 Canyon
and Watana impoundments. During 1980 and 1981, Gipson et
a1. ( 1982) emp1 oyed radio-tracking, snow-tracking, and
aerial snow-tracking to determine fox distribution, abun-
dance, and habitat use. Food habits were studied from scat
ana1ysis, stomach content analysis, and examination of food
remains at dens and on fox trails. Aerial surveys were
conducted to locate fox dens, and dens were surveyed
periodical1y throughout summer to determine use.
(i) Habitat Use
Foxes in the midd1e Susitna Basin appear to prefer
relatively high elevation areas near or above the
timberline (Gipson et al. 1982). Black spruce flats
upstream from Vee Canyon are also common1y·used.
Some foxes use low elevation tributary deltas during
autumn, then shift to a1pine zones as snow depth and
volume of water flowing over the ice increase. Other
foxes remain above timber1ine year round. Trails in
snow indicated that foxes common1y foraged in winter
in areas above tirnber1ine frequented by large flocks
of ptarmigan.
E-3-361
4.2_-Baseline Description
In aerial transects of furbearer tracks in fall 1980,
almost twice as many tracks (151 vs. 79) were located
south of the river as opposed to the north (Table
E.3.125). This is in contrast to the greater number
of active dens found on the north side. However, at
the upper reaches of the proposed impoundment, fox
density was observed to increase markedly and
transects 1-11 (see Figure E.3.101 and Table E.3.125)
had almost even numbers of tracks on the north and
south sides (67 on the north and 51 on the south).
All of the north side-south side discrepancy is
accounted for in transects 12-14. The south side of
the river above Vee Canyon changes from mountainous
terrain to open, marshy flats which Gipson et al.
(1982) say characterize good fox habitat.
Gipson et al. ( 1982) report that searches along the
Susitna River and lower elevations of tributaries in
1 ate winter and early spring 1980 produced no evi-
dence of foxes in these areas. Tracks and other
signs were noted on river banks in the following late
fall and early winter.
-Denning Habitats
Nineteen fox dens were located in the middle basin
during baseline studies in 1981 (Figure E.3.102)
(Gipson et al. 1982). Sixteen dens were located
north of the Sus i tna River with several dens con-
centrated in the upper Watana Creek and upper Dead-
man Creek drainages. Gipson et al. ( 1982) report
that several undiscovered dens are likely to exist
on the south side of the river, but the aspect,
physiography, and vegetation appear more favorable
for denning and hunting on the north side.
Dens are typically situated on an aspect facing
south and/or west, and on well-drained prominences
up to 16 feet (5 m) above surrounding areas. Dens
are also characterized by proximity to a lake of
over 10 acres (4 ha) or a creek. Dens were found
between 3280 and 3940 feet (1000 and 1200 m)
elevation in areas of rolling hills adjacent to
mountains. All active dens located were in or near
areas of medium-to-high ground squirrel density.
E-3-362
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4.2-Baseline Description
Foxes in this study area remained at den sites into
October, nuch 1 ater than in other areas of Alaska
(see Gipson et al. 1982) or elsewhere {Sheldon
1950, Storm 1972). Foxes in the Su sitna project.
area appear to use den sites throughout the winter,
as evidenced by clearing of snow from at least one
entrance of most dens visited by observers during
winter months.
-Food Habits
Principal foods of foxes in the middle Susitna
Basin were determined by Gipson et al. (1982)
through direct observation of foxes, identification
of remains at dens and on trails, scat analysis,
and stomach analysis of foxes taken by trappers.
In spring and summer, diets include arctic ground
squirrels, red-backed voles, and singing voles.
Ptarmigan are taken throughout the year and are
major components of the diet in winter. Muskrats
are taken where available and may be relatively
important tQ foxes in the vicinity of large lakes
such as Stephan Lake, Clarence Lake, and Deadman
Lake. Dispersing young muskrats and muskrats at
pushups are especially vulnerable to predation by
foxes.
Carrion is also identified as important by Gipson
et al. {1982) based on the observations of foxes
feeding on a carcass of moose and another of
caribou near Watana Camp and on a sheep carcass on
the east fork of Watana Creek.
Snowshoe hare are presently scarce in the Su sitna
study area and are, therefore, unimportant in the
diet of foxes there. The scarcity of hares may be
responsible in part for the relatively low number
of foxes in the area, as well as the seasonal
shifts by -foxes to higher elevations where
ptarmigan are available.
-Home Range
Summer home ranges vari ~d from 4544-8064 acres
{ 18.3 to 32.7 km2) in the Su sitna study area with
little difference in home range size between males
and females {Gipson et al. 1982). The larger size
E-3-363
4.2 -Baseline Description
of home ranges in the Su sitna study area compared
with studies in midwestern states was attributed by
Gipson et al. (1982) to the greater availability of
food in the midwest.
(ii) Population Characteristics
(g) Lynx
Six of 19 dens found in a 432,640 acres ( 1751 km2)
area in the middle basin in summer 1981 were active
(Gipson et al. 1982). Dens were classified according
to size and use as described in Table E.3.126;
locations are mapped on Figure E.3.102. A seventh
den was probably also active, giving a density of one
family per 61,440-72,320 acres (250-292 km2) (a
family usually consists of 4-6 foxes). Gipson et al.
( 1982) report that the most reasonable estimate of
density is one family per 20,480 acres {83 km2)
based on the assumption that at 1 east one third of
active dens were found in 1981.
Transect data demonstrate a marked increased in
number of fox tracks encountered as one progresses
upstream from Devil Canyon to the Tyone River. Fur
harvest reports of the Alaska Department of Fish and
Game indicate that 983 red fox pelts were exported
from GMU 13 between 1976 and 1981. Four dealer loca-
tions account for 92 percent of the basin harvest:
Cantwell, Gakona, Copper Center, and Glenallen.
Cantwell, which lies closest to the study area, com-
prised 11 percent of the total 5-year GMU 13 export.
Gipson et al. (1982) indicate that interviews with
furdealers and trappers identify the upper Copper
River-Solo Hills-Maclaren River area and the Crossman
Lake area west of Paxson as the source of most foxes
taken. Dean Wilson (personnel communication cited by
Gipson et al. 1982) indicated that most of the furs
he buys are taken in open, marshy country and that
prime fox habitat decreases from the Maclaren River
to the Tyone-Oshetna-Su sitna areas as flat open
plains rise to mountainous alpine terrain. Gipson et
al. ( 1982) conclude that the Susitna project study
area supports a low-density fox pOJXJlation relative
to other areas in Alaska.
The distribution of lynx in the middle basin is very limited
at present. Tracks and scats have been found in several
areas including the mouth of Goose Creek {probable lynx
E-3-364
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.....
'
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4.2-Baseline Description
(h)
tracks seen from the air on November 19, 1980, and a dense
concentration of scats and tracks found on October 22,
1981); the mouth of Jay Creek {tracks seen on October 30,
1981); and at ong Goose Creek, 1 mi 1 e (1. 6 k.m) from the mouth
(tracks seen on November 3, 1981)(Gi pson et al. 1982).
However, considering the amount of effort involved in aerial
and ground fu rbea rer surveys, these t rae k records i nd i cate
that few lynx occur in the middle basin.
In the past, lynx were apparently fairly numerous in the
canyon country of the Susitna River, being found primarily
in the forests along the river (H. McMahan, pers. comm.
cited by Gipson et al. 1982). Trappers in the vicinity of
the impoundments reported no sightings of lynx or their
tracks, and reports from trappers in the Gold Creek area
suggest that lynx have been uncommon there in recent years
as well (Gipson et al. 1982).
Lynx population levels fluctuate in response to availability
of snowshoe hares (Keith 1963), which were uncommon in the
Susitna Basin in 1981 (Kessel et al. 1982a). Gipson et al.
{1982) reported that historically, the frequency of natural
forest fires increased from Portage Creek to the Tyone
River, and speculated that snowshoe hare (and lynx) numbers
may have been higher in the past. However, Kessel et al.
{ 1982a) note that no fires have occurred in the Su sitna
Basin in the recent past, and they report that hare numbers
appear to be chronically low in the Susitna area. If fire
or other habitat change leading to an increase in snowshoe
hares occurs, lynx populations will likely also increase •
However, for the present, lynx are uncommon in the area.
Coyote
The distribution of the few coyotes occurring in the middle
basin is generally 1 imited to those areas downstream from
De vi 1 Creek. No coyotes or their tracks were observed by
Gipson et al. (1982) during baseline studies in the Susitna
area, although several sightings of coyotes in fall 1980
were reported to them. Other sightings of coyotes, or their
tracks, have also been reported in the Gold Creek and Canyon
areas (H. Larsen 1981 pers. comm.; R. Roull ier 1981, pers.
comm. cited by Gipson et al. 1982). Coyotes have not been
seen or taken by trappers upstream from Devil Creek. The
distribution and abundance of coyotes in the Susitna area is
probably 1 imited by wolves rather than by habitat, food
availability, or trapping pressure. Wolves are usually
aggressive toward coyotes within their home range (R.
Peterson and J. Woolington 1982 pers. comm.).
E-3-365
4.2-Baseline Description
(i) Short-tailed Weasel
Short-tailed weasels are locaily abundant in the middle
basin, and their tracks have been observed in a variety of
habitat types at elevations ranging from the banks of the
Susitna River to over 4290 feet (1500 m). Transect surveys
conducted in November 1980 yielded 746 short-tailed weasel
tracks, 328 (44 percent) of which were counted on a single
transect near the Tyone River (Table E.3.121). Most of the
tracks (489 or 66 percent) were observed in woodland white
or black spruce vegetation types; an additional 190 (25
percent) were counted in medium shrub types (Gipson et al.
1982). It appears that short-ta i 1 ed weasels can meet their
food and cover needs in a variety of habitat types. Short-
tailed weasels have been taken both deliberately and
incidentally by trappers on upper Tsusena Creek, in the Fog
Lakes area, and elsewhere in the study area; but they are
not a species of major economic importance.
(j) Least Weasel
Least weasels occur at least sparsely throughout the middle
basin and may be locally abundant. However, their small
size and secretive behavior makes confirmation of their pre-
sence difficult. Several sets of tracks believed to be
those of least weasels were seen in March 1980 along lower
Watana Creek. The carcass of one least weasel, taken by a
trapper at Fog Lakes, was obtained in February 1981, and a
1 ive 1 east weasel was observed near the southeast edge of
proposed Borrow Site A on October 25, 1981 {Gipson et al.
1982). The pelts of least weasels have practically no com-
mercial value (Svendsen 1982), and, thus, information from
trapping returns is rarely available to supplement direct
observations.
4.2.3 -Birds
Little was known about the birds of the middle Susitna Basin
prior to initiation of baseline studies for the Susitna
Hydroelectric Project. Baseline data on breeding birds of the
middle basin presented here are primarily those collected and
provided by Kessel et al (1982a, Personal comrrunication, and
unp..rblished data), University of Alaska Museum. Data presented
are from 3 sources: (1) 12-25 acres {10 ha) bird census plots,
(2) ground and aerial census of waterbodies, (3) helicopter
surveys and ground reconnaissance of raptor nesting habitats~ and
(4) additional data on species presence and phenology and habitat
use were obtai ned from casual observations of investigators and
observations solicited from others working in the region (Kessel
et al. 1982a, 1982). These data have been 1 iberally drawn upon
E-3-366
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~·
....
4.2 -Baseline Description
to provide ITllch of the following text. However, additional
information has been incorporated wherever appropriate.
Locations of census plots are shown in Figure E.3.103. Sites
were selected in relatively uniform patches of vegetation that
represented each of the major woody avian habitats present in the
region (Kessel 1979). The alpine tundra plot was selected to
include several of the widespread avi~n habitats of higher
elevations. Each plot was censused 8 times between May 20 and
July 3, 1981 (and 8 times between May 24 and July 2, 1982).
Methods were modified from the territory census method
(International Bird Census Committee 1970).
Locations of censused waterbodies are shown in Figure E.3.104.
Ground censuses of 28 waterbod i es were conducted between Ju 1 y 8
and 29, 1981. Each waterbody was censused once by observers
walking the shoreline or canoeing the edges, or by both methods
siiTllltaneously. Aer·ial surveys to monitor use of waterbodies
during migration were conducted by helicopter between September 7
and October 4, 1980; May 3-26, 1981; and September 15 to October
23, 1981. The number of waterbodies surveyed varied each survey;
the average was 34. Flights were made at approximately 50 mph
{80 km/h) and between 100 and 250 feet (30 and 75 m) altitude.
When flocks were encountered, the helicopter circled widely and
slowly for an accurate count and identification. On lakes, the
helicopter followed the shorel·ine for the survey;. a single pass
was made over smaller waterbodies. Large lakes were surveyed in
sections.
Raptor surveys were designed specifically for cliff-nesters
(especially golden eagles, gyrfalcons and peregrine falcons) and
large tree-nesters (especially bald eagles). Information on
other species was obtained incidental to these surveys and during
ground-based plot surveys and waterbody surveys.
Raptor surveys were conducted in the middle basin by helicopter
on July 6, 1980 and May 16 and 17, 1981 (Kessel et al. 1982a).
All cliff nesting habitat and stands of large white spruce and
cottonwood within approximately 3 mi 1 es {5 km) of the Su sitna·
River and its tributaries from Portage Creek (1980) and the
Indian ·River {1981) to· the mouth of the Tyone River were
surveyed. The proposed access routes were surveyed on July 3 and
5, 1981. ~ring surveys, the helicopter moved slowly past cliff
faces at approximately 30-40 m distance until the face was
considered adequately scanned. In 1980 and 1981, active nests
were visited from the ground between May 20 and July 13, 1981.
In addition, all potential appearing peregrine falcon nesting
habitat (e.g., especially partially vegetated cliffs) was
examined by helicopter and on foot in June 1981 •
E-3-367
4.2 -Baseline Description
A total of 135 species of birds were recorded in the middle
basin. Their relative abundances (see Appendix 3.E) were largely
a function of habitat availab·ility. The most abundant species
in the project , area are common redpoll, savannah sparrow,
whitecrowned sparrow, Lapland longspur, and tree sparrow.
Of the 135 species, 15 are ranked as rare in the middle and upper
basin on the basis of current information: 4 raptors (osprey,
American kestrel, snowy owl, boreal owl); 3 species of ducks
(gadwall, blue-winged teal, ring-necked duck); 4 shorebirds {up-
land sandpiper, turnstone spp., surfbird, sanderling); 3 small
land birds {black-backed three-toed woodpecker, western wood
pewee, yellow warbler); and ruffed grouse. Most of these species
were rare because they were either at the periphery of their
geographic ranges or were limited by a lack of appropriate
habitat. All 15 species are represented by larger pollJlations in
other portions of Alaska.
Baseline data on distribution, abundance, and habitat use of bird
populations in the lower Susitna floodplain were collected by the
University of Alaska Museum (Kessel et al. 1982b). Three types
of a vi an surveys were conducted between De vi 1 Canyon and Cook
Inlet: (I) spring aerial surveys of waterbirds in 1981 and 1982;
(2) a ground survey of all bird species in early summer 1982; and
(3) an aerial survey for bald eagle nests in summer 1982.
Spring aerial surveys were made on May 7, 1981, and May 10, 21,
and 28, 1982. Flights were made with 2 observers and a pilot by
fixed-wing airplane or helicopter at an altitude of 100-200 feet
(30-60 m) between 60-100 mph (95-160 km/h r). Flight patterns
varied with river morphology to obtain the most complete count
possible. In wider, braided sections, and in the delta, an $-
pattern between the outermost banks was followed. Where the main
channel was split, each portion of the channel was surveyed
separately. Single, u nbrai ded channels were surveyed with a
direct flight pattern.
The ground survey was conducted between Curry and the river mouth
from June 10-21, 1982. Extensive, uniform patches of each of the
major terrestrial habitats, as sighted from the river, were sur-
veyed each morning on foot.
Surveys for nesting bald eagles were conducted in the 1 ower
Susitna River floodplain in April 1980 by the US Fish and
Wildlife Service, in late June 1981 byTES and on July I, 1982 by
the University of Alaska M.Jseum (Kessel et al. 1982b). Three
observers and a pilot flew an S-pattern searching for
mature/decadent cottonwood forests, which is favored bald eagle
nesting habitat along the lower river. Nesting habitat was
E-3-368
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....
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4.2-Baseline Description
thoroughly searched from the air and an attempt was made to
locate all previously recorded nests. Additional nests were
1 ocated during waterbird and ground surveys •
At 1 east 82 bird species were recorded a 1 ong the 1 ower Su sitna
floodplain in June 1982 (see Appendix 3.F).
(a) Raptors and Raven
Definitions for raptor "nesting locations" and "nest sites"
are given in Appendix 3.I.
A total of 10 raptor species were recorded upstream from
Devil Canyon. Kessel et al. (1982a) recorded 10 raptor
species upstream from Devil Canyon. Five of these species
(six including the common raven, a functional raptor that
often provides nests for some rapt or species) are known to
nest in the area, and at least two additional species
probably breed there (Appendix 3.E). The presence of Broad
Pass to the west and a pass to the east containing the
Richardson Highway, both commonly used by a variety of
migrating raptors (H. Springer, pers. comm., D. Roseneau
1982 pers. comm.), and the absence of comparable passes in
the immediate project area suggest that any migratory move-
ments of raptors in the project area would 1 ikely be com-
prised primarily of local breeders.
A total of 53 raptor/raven nesting locations have been
reported from the middle basin (White 1974; Kessel et al.
1982a; B. Kessel 1982 pers. comm.; see Table E.3.127). At
least two of these locations {GE-6 and GE-12) do not appear
to exist and probably represent two of the remaining 51
locations (see Table E.3.127). Active nesting locations in
1980 included 6 golden eagle, 4 bald eagle, 1 common raven,
and 1 nesting location of an unidentified species (probably
gyrfalcon). Active nesting locations in 1981 included 6
golden eagle, 5 bald eagle, 1 gyrfalcon, 2 goshawk {dis-
covered during ground-based plot search), and 4 common
raven. One additional active golden eagle nesting location
was discovered during the course of other work in 1982.
Nesting locations that were not active in 1980 and 1981 pre-
sumably functioned either as alternates or, in some cases,
may be used by additional pairs in years when pop.llation
levels may be 'higher. Table E.3.128 shows the general
breeding phendogy of golden eagles, bald eagles, gyrfalcons
and ravens in Alaska. These schedules are applicable to the
middle basin.
In 1974, White (1974) found 14 active nesting locations
within the same area of the middle Susitna Basin:
E-3-369
4.2 -Baseline Description
2 gyrfalcon, 3 bald eagle, 9 common raven. He also reported
a single gyrfalcon at one additional known nesting location
(GYR-I; see Tble E.3.127) and observed 2 single peregrine
falcons that did not apear to be nesting [see Section
4.2.3(a)(iv)]. White (1974) also reported an addition 13
inactive nesting 1 ocat ions, ascribing 7 to ravens, 3 to
golden eagles, 2 to bald eagles, and 1 to goshawks. The
apparent change in number of pairs of golden eagles and
ravens present in th middle basin between 1974 and 1980 -
1981 may be the result of a combination of several factors,
including differences between observers and survey
intensity, and natural variations in breeding poPJlation
levels as a result of spring nesting conditions or changes
in prey availability and vulnerability (Kessel et al. 1982a,
D. Roseneau 1982 pers. comm.).
No s pee i fi c data on migratory movements of raptors were
collected in the middle basin. However, the presence of
Bread Pass to the west and the Richard son Highway pass to
the east, both commonly used by a variety of migrating rap-
tors and other birds (B. Kessel 1982 pers. comm., H.
Springer 1982 pers. comm., D. Roseneau 1982 pers. comm.).
and the absence of comparable passes in the immediate pro-
ject area, suggest that migratory movements of raptors in
the project area would likely be comprised of local
breeders.
Distribution, abundance, and food habits are discussed beJow
for each species. Although no data were collected on food
habits of raptors in the Susitna Basin, they are unlikely to
differ greatly from raptors in similar situations in other
parts of the state.
(i) Golden Eagle
Estimates of breeding populations of golden eagles in
south-central Alaska, including the Alaska Range, are
not available. However, this raptor nests at low
densities throughout most of the state, including the
arctic slope, and nesting occurs almost exclusively
on cliffs (Roseneau et al. 1981). Golden eagles
regularly build and maintain a number of sillllltaneous
nests, often at locations several kilometres apart,
which are used as alternates in different years
(Brown and Amadon 1968, McGahn 1970~ Roseneau et al.
1981).
The abundance of golden eagles in the central Alaska
range is 1 i kely to be 1 ower than that found in the
E-3-370
....
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4.2-Baseline Description
middle Susitna basin. In most of the Alaska Range,
cliff-nesting locations for raptors tend to be widely
dispersed (Bente 1981, P. Bente 1982 pers. comm., D.
Roseneau 1982 pers. comm.). However, if nesting
cliffs are available, pairs of golden eagles may nest
relatively close to one another. Murie (1944) found
golden eagles nesting as close as 1.0 and 1.5 miles
(1.6 and 2.4 km} apart in Denali National Park in
1941 and 1939, respectively.
The abundance of active golden eagle nesting 1 oca-
t ions present in the middle basin in 1980 and 1981
(one pair per 9.18 miles [14.8 km] of river) (Kessel
et al. 1982a) was similar to that found along the
Brooks Range portion of the Dalton Highway in 1979
(one active nest per 9.73 miles [15.7 km]) (Roseneau
and Bente 1979). The latter abundance appears to be
one of the highest reported in Alaska. White et al.
(1977) suggested that local populations of golden
eagles may increase during years of high snowshoe
hare populations; however, hares are relatively
scarce in the middle basin in 1980 and 1981 (Kessel
et al. 1982a). Murie (1944} noted that arctic
ground squirrels were a major prey of golden eagles
in Denali National Park in 1939-1941, and these
rodents were abundant in the middle basin area during
the study.
Golden eagles are opportunistic hunters. Diets vary
from region to region according to prey availability
and vulnerability. When available, mammals are an
important component of their diet (up to 70-90 per-
cent by weight), but birds and carrion are also often
important. Nonbreed·ing of golden eagles occurs in
some years, and there is some evidence to suggest
that prey avai 1 ab·il ity may influence breeding success
(Brown and Amadon 1968}.
In Alaska, there are few published reports of prey
items found at golden eagle nests. Conmon items
have included ground squirrels, marmots, snowshoe
hares, ptarmigan, ducks, and other waterfowl (D.
Ro seneau 1982 pers. comm.)
Occasionally, both arctic and red foxes are taken.
One pair on the Seward Peninsula took as many as 5 -
6 red foxes during the summer, and the fledgling from
that nest attacked a red fox about 2 weeks after
1 eavi ng the nest (D. Roseneau 1982 pers. comm.).
E-3-371
4.2 -Baseline Description
Pairs nesting along sea coasts also take a variety of
seabirds (both alive and as carrion), including young
gulls and rrurres (D. Roseneau 1982 pers. corrvn.).
Carrion, often in the form of large game animals, may
be particularly important during the early spring and
the fall. Carrion also appears to be very important
to sub-adu 1t golden eagles. Large numbers of sub-
adu 1 ts frequent the ca 1 vi ng and post-ea 1 vi ng grounds
of caribou herds. Up to six sub-adults have been
found feeding at one time on wolf-killed and bear-
killed caribou, and sub-adults occasionally kill
caribou calves (Roseneau and Curabole 1976, Roseneau
et al. 1981).
(ii) Bald Eagle
In Alaska, the majority of bald eagles nest coastally
in southeast, southcentral and southwest Alaska;
these POPllations may exceed several thousand pairs.
North and west of the Alaska Range, numbers decline
markedly and most nesting is associated with wetlands
in portion of the Yukon (including the Tanaa) and
Kuskokwim River drainages (see Roseneau et al. 1981).
In total, surveys for nesting bald eagles in the
lower Susitna floodplain discovered 38 nest sites,
some of which undoubtedly represent a 1 tern ate nest
sites or alternate nesting locations (see Table
E .3.129). In 1982, the year for which data are the
most complete, only 14 of the 24 nest sites reported
in 1980-81 were relocated, but 14 new nest sites were
found. A few nesting locations and nest sites found
in 1980 and 1981 may no longer exist as a result of
blowdown, bank erosion or beaver activity (see
Roseneau and Bente 1981). Of the 28 total known nest
sites reported in 1982, 17 were active and 11 were
inactive. Similar proportions of active versus inac-
tive nesting locations and nest sites have been found
along the Tanana River (Roseneau and Bente 1981).
The amount arrd suitability of bald eagle nesting
habitat and the number of nesting bald eagles in-
creased markedly downstream from Indian River (see
Table E.3.129). Most of the bald eagle nesting loca-
tions were concentrated in three sections of the
floodplain: (1) between Talkeetna and the Parks
Highway Bridge; (2) between Kashwitna Lake and the
mouth of the Yentna River; and (3) from Bell Island
to the mouth of the Susitna River (Kessel et al.
1982b). The number of bald eagle nests and nesting
pairs per river mile along the lower Susitna River
floodplain is comparable to that found on the Tanana
River (D. Roseneau 1982 pers. comm.).
E-3-372
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4.2 -Baseline Description
(iii)
Bald eagles are opportunistic in their feeding
habits, and diets vary from region to region
according to the availabiltiy and vulnerability of
prey species. Although they take a variety of live
prey, bald eagles often rely heavily on local sources
of carrion, may be attracted to dumps, and may pirate
prey from other raptors, particularly osprey (Brown
and Amadon 1968}. Fish and birds are both important
components of their diet.
In Alaska, bald eagles often rely on dead or dying
salmon when they are available, and take a variety of
other species of fish in shallow water or as carrion
a 1 ong shore 1 i nes. Waterfowl and seabirds (a 1 c ids,
anatids and larids) also figure prominently in their
diet, particularly in some coastal regions (e.g., the
Aleutian Islands). Ritchie (1982) found fish and
a vi an prey to have nearly equa 1 frequency of occur-
rence (43.8 and 43.7 percent, respectively) in re-
mains at nests along the Tanana River, Alaska, where-
as mammal remains occurred in 12.6 percent of nests.
Remains of An as spp. (mostly mallard) canst ituted 17
of 28 occurrences of avian prey. Dead, dying, or
injured birds are often taken from the water surface,
but eagles are also quite capable of surprising and
taking uninjured waterfowl and seabirds from the
water surface or in the air. Even geese may be occa-
sionally taken in flight (Brown and Amadon 1968), and
sandhi 11 cranes and swans have also been taken (D.
Herter 1982 pers. comm. and A. Springer 1982 pers.
comm.).
Diets of bald eagles nesting along the Susitna River
are probably similar to diets of eagles nesting along
the Tanana River. Salmon are undoubtedly important
to many pairs in late summer and fall. Earlier in
the year, other fish species (particularly whitefish,
suckers and grayling) and waterbirds (especially
waterfowl) constitute the bulk of their diet. Snow-
shoe hares and JTU skrats may also be taken on occa-
sion.
Gyrfalcon
Gyrfalcons are not abundant in southcentral and cen-
tral Alaska, but they relJll arly nest throughout the
Alaska Range. Cade (1960) estimated the total Alaska
population at only about 200-300 pairs. Roseneau et
a 1. ( 1981) considered that · estimate too 1 ow, but
doubted that the population exceeded 500 pairs.
E-3-373
4.2-Baseline Description
Numbers of nesting gyrfalcons may vary considerably
between years (Cade 1960, Roseneau 1972, Swartz et
al. 1975) but variation may be less over larger
regions (Roseneau 1972). The majority of the Alaskan
population is found in northern and western Alaska
(Roseneau 1972, Roseneau et al. 1981), and gyrfalcons
there tend to exhibit relatively 1 ow site fidelity
from year to year (Cade 1960 and Roseneau 1972).
However, in the Alaska Range, where suitable nesting
cliffs are fewer more widely dispersed, most sites
appear to be used more regularly (Bente 1981).
Gyrfalcons are year-around residents of the arctic
and subarctic and are also opportunistic hunters.
During the summer their diets vary according to prey
ava i 1 abi 1 ity and vu 1 nerabi 1 ity (Roseneau 1972), but
they typically rely on only a few principal prey
species for the bu 1 k of their food. ·
The principal summer prey species include ptarmigan
(often 70-90 percent by weight of their diet), arctic
ground squirrels, and, in some regions, long-tailed
jaegers (White and Cade 1971; Roseneau 1972). Migra-
tory birds typically constitute no more than 15-20
percent by weight of their summer diet. In some
regions of interior Alaska (e.g., the Alaska Range),
ground squ i rre 1 s surpass ptarmigan in importance
(Cade 1960 and Roseneau 1972). In the winter, gyr-
falcons are almost solely dependent on ptarmigan
(Platt 1976 and Walker 1977), although in some high
arctic regions, arctic hares are also important
winter prey. The year-round reliance on ptarmigan
and the high utilization of small mammals in the
summer are important factors that have helped gyr-
falcons to avoid serious biocide contamination and
thus maintain healthy, non-endangered populations in
the arctic.
Despite the reliance on a few principal prey species,
gyrfalcons are capable of shifting to other food
sources during the breeding season if the availabil-
ity of a few prey species changes dramatically-.-pro-
vided that other prey species are present (White and
Cade 1971; Roseneau 1972). It has also been sug-
gested that gyrfalcons may not !}reed in some years
when prey availability is low.
E-3-374
r--
( i v)
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Peregrine Falcon
Per eg r i n e f a 1 cons are d i s t r i b ut ed wo r 1 d wi d e .
Peregrines are specialists in avian prey and prey
weights range from 50 g or less to over 600 g. In
Alaska, the 2 endangered races, Falco ,peregrinus
anatum and F .p.sundrius, rely on a broad prey base
cons1 sting of a variety of shorebirds, waterfowl,
passerines and occassional small mammals ( Cade 1960,
Roseneau et al. 1981). 'In contrast to gyrfalcons,
peregrines are diverse in their feeding habits,
concentrating more on categories of prey, such as
shorebirds, than on individual species. Their high
use of migratory prey . (especially shorebirds) on
northern breeding grounds and on wintering grounds as
far south as 30°S in South Anerica has contributed to
their endangered status as a result of biocide
contamination. Recently, pollutant residues
(biocides) have tended to decline in peregrine tissue
(A. Springer, unpublished data). Since the late
1970's, in most of Al ask and in some other parts of
North Jlmerica, nllllbers andproductivity of both
endangered races have increased (USFWS unpublished
data) .
There were no confirmed sightings of peregrine fal-
cons in the middle Susitna BAsin during 1980, 1981,
or 1982, despite the substantial nllllber of man-hours
spent on ornithological field work and on raptor
surveys {Kessel et al. 1982a; B. Kessel 1982 pers.
comm.). White (1974) saw tWJ individual peregrines
during a June 10-15, 1974, survey; however, he found
no sign of nesting. One of the birds was a 11 Single
adult male ... roosting on a cliff about 4 miles up-
river from the Devil Canyon Dam axis," and the other
was "a sub-adult ... about 15 miles upriver from the
Devil Canyon Dam axis.11 .White (1974) stated that the
Yenta-Chul itna-Susitna-Matanuska drainage basin
"seemingly represents a hiatus in the breeding range
of breeding peregrines ... ," and Roseneau et al.
{1981) stated that "the Susitna and Copper riv:Drs
both provide ... very few ... potential nesting areas for
peregrines .11
The Susitna River drainage does not provide habitat
typical of or comparable to any important areas of
peregrine nesting habitat in the boreal zone of
Alaska {e.g., upper Porcupine, upper Yukon-Charley,
E-3-375
~.2 -Baseline Description
middle Yukon, lower Yukon, upper Tanana and Kuskokwim
river drainages). Key elements of the exisitng
habitat in the Susitna River drainage, in addition to
the surveys conducted for them, provide reasonable
evidence that peregrines do not presently nest in the
project area and that biologically significant
numbers of them are unlikely to occur there naturally
in the future with or without project developnent.
(v) Other Raptors
No breeding records for owls were reported in the
middle basin by Kessel et al. (1982a). Three of the
five species of owls (great horned owl, hawk owl, and
boreal owl) that have been recorded in the middle
basin are year-round residents and probable breeders
in mixed and coniferous forests (Appendix 3.E). The
short-eared owl occupies open habitats in small
numbers in summer, and a few may breed in the region.
Snowy owls, occasional migrants, are rare in the
middle basin.
Only single records of two species of owls (great
horned owl short-eared owl) were obtained along the
1 ower Su sitna River during the spring surveys
(Appendix 3.F). Great horned owls are 1 ikely resi-
dents and breeders, especially in mature cottonwood
stands along the river and sloughs.
Suitable nesting habitat for goshawks and great-
horned owls consists primarily of occasional mature
paper birch and paper birch-white spruce stands,
which are most convnonly found downstream from Devil
Canyon (D. Roseneau 1982 pers. comm.). Some nesting
habitat for other tree-nesting species (e.g.,
red-tailed hawks, American kestrels, sharp-shinned
hawks, boreal owls, and hawk owls) and ground-nesting
species (e.g., merlins, northern harriers, and
short-eared owls) also occurs in the Su sitna Basin,
but no concentrated areas of nesting habitat are
known or expected to occur.
The diet of owls and smaller raptors consists mainly
of small rodents and small birds. Northern harriers
feed on either small rodents or small birds in open
terrain. American kestrels feed primarily on in-
sects, small mammals, and occasionally small birds.
Owls (great-horned owl, short-eared owl, hawk owl),
and boreal owl) are generally specialists on small
E-3-376
"--,
-
-
-
1""'1
I
r
I
-
-
4.2-Baseline Description
manvnal prey, though great-horned owls may also take
birds. Sharp-shinned hawks and merlins are
specialists on small avian prey. Goshawks and
red-tailed hawks rely on a combination of small
mammal and avian prey.
(b) Waterfowl and Other large Waterbirds
The middle basin and the lower Susitna River floodplain
above the delta do not support large concentrations of
waterfowl or other waterbirds during either migration or the
breeding season (Kessel et al. 1982a, 1982b). Although low,
a vi an use of discrete waterbod i es and waterbody groups in
the middle basin varied considerably. An analysis of the
relative importance of discrete wetland areas is included to
identify potentially important areas.
The species composition of waterfowl in the middle basin
showed some differences from that of central Alaska as a
whole, in part reflecting the subalpine nature of rruch of
the study area (Kessel et al. 1982a). Oldsquaw and black
seater were the most productive of the waterfowl in 1981
(Table E.3.130). Both species are primarily tundra nesters,
and the Alaska Range is the only inland nesting location
known for the black seater in Alaska (Gabrielson and lincoln
1959). The pintail, one of the most numerous ducks ·in
central Alaska, occurred in relatively small numbers in the
study area, in spite of the fact that both 1980 and 1981
were high population years for pintails in Alaska because of
severe drought in the Canadian prairie provinces (King and
Conant 1980, Conant and King 1981).
(i) Migration-Middle Basin
The middle Susitna Basin, which is on a high plateau
between the Alaska Range and the Talkeetna Mountains,
does not appear to be a major migration route for
waterbirds {_~antra U. S. Corps of Engineers 1977)
(Kessel et al. 1982a). A relatively small number of
individuals were seen during three surveys in spring
1981 and six and five surveys in fall 1980 and 1981,
respectively (Tables E.3.131, E.3.132 and E.3.133).
Scaup, including both 1 esser and greater scaup, were
the most numerous species group during ·both spring
and fall. Relatively large numbers of mallards and
American wigeon a 1 so moved through during both sea-
sons. Pintail s were common during spring migration
but uncommon in fall. Few geese or cranes were seen
at either season (Kessel et al. 1982a).
E-3-377
4.2-Baseline Description
The middle Susitna Basin was less important to
migratory waterfowl in spring than fall (Kessel et
al. 1982a). Because ice breakup does not regularly
occur until mid-May on many lakes in the middle basin
little open water was available to early migrating
waterbirds, such as the dabbling ducks and common
goldeneye. Early migrants used the Susitna River
itself and the thawed edges of 1 akes. Use of the
middle basin•s water bodies increased toward the end
of May, concurrent with the availability of more open
water and the influx of the later arriving loons,
grebes, scaup, oldsquaw, seaters, and mergansers
(Kessel et al. 1982a).
The pattern of fall movement in the middle basin was
similar to that known for the rest of central Alaska
(Kessel et al. 1982a}. Peak numbers of American
wigeon, pintail, and green-winged teal occured during
the first half of September; loons, grebes, and scaup
during the second and third weeks of September; and
mallards, seaters, buffleheads, and goldeneyes, from
the 1 ast third of September to mid-October. Trum-
peter and whistling swan migration occured between
the 1 ast week of September and the end of October
(Kessel et al. 1982a}.
(ii) Summer Use of Waterbodies-Middle Basin
The wetlands of the middle basin supported relatively
few waterbirds during the summer. An average density
of only 0.09 adult loons, grebes, ducks, gulls, and
terns/acre of wetlands {22.5/km2) and 0.01 broods/
acre of wetlands (2.9/km2) were found on 28 inten-
sively surveyed water bodies in summer 1981 (Table
E.3.130). By comparison, a census of 13 waterbodies
in the upper Tanana River valley, similar in size
class distribution to those surveyed in the middle
basin, had average densities of 0.74 adult loons,
grebes, ducks, gulls, and terns/acre of wet-lands
(183.0/km2) in 1977 and 0.45 adults/acre
{110.5/km2) in 1979 (Spindler et al. 1981 cited by
Kessel et al. 1982a). Even when gulls and terns are
excluded, the density of broods in the Tanana River
Valley was markedly higher, at 0.03/acre {6.2/km2)
than in the middle Susitna basin. Productivity in
the eastern portion of the upper Tanana River valley
study area in 1979 was 30-40 percent lower than his-
torical levels typical of Minto lakes, Tetlin Lakes,
and portions of the Yukon Flats are considered
E-3-378
-
-(
-
-
-
4.2 -Baseline Description
among the most productive wetlands in Alaska {J. G.
King, U.s. Fish and Wildlife Service, Perssonal
communications cited by Kessel et al. 1982a). Thus,
the waterbodies of the middle basin appear to support
a relatively impoverished popJlation of waterfowl
during the summer (Kessel et al. 1982a).
As discussed earlier, the species composition of
waterfowl reflects the su ba 1 pine nature of the study
area with oldsquaw and black scoter {tundra nesters)
being the most productive s pee i es. Trumpter swans
also breed commonly on the eastern end of the study
area, from the vicinity of Oshetna River to at least
the Maclaren River. On an informal flight over ponds
of this area on August 4, 1981, Kessel et al. (1982a)
recorded 19 observations of trumpeter swans. Forty
adult birds were seen, including 9 pairs with broods
(28 cygnets). This are.a is on the western edge of
habitat used by the Tal.keetna Basin trumpeter swan
pop.J.lation which has more than doubled in the past 5
years (King and Conant 1981).
{iii) Relative Importan{:e of WaterBodies-Middle Basin
Kessel et al. (1982a) calculated relative importance
values (I.V.) for each lake surveyed, which combined
3 commonly used measures of habitat quality: number
of birds, density, and species richness. The I.V.
values are an index to the relative importance of
each waterbody included in a particular computation
of the index, and are patterned on concepts presented
by Curtis and Mcintosh {1951). The I.V. for each
waterbody was calculated each season as the sum of 3
ratios: {1) the mean number of birds per census for
the water body divided by the sum of the means per
census for all waterbodies censused; (2) the mean
density of birds per census on the waterbody divided
by the sum of the means per census for a 11 water-
bodies censused; and (3) the mean number of species
per census for the waterbody divided by the sum of
means on all waterbodies. Figures E.3.105 and
E.3.106 compare relative I.V. ratings for all lakes
surveyed in fall 1980 and spring 1981 respectively.
Seasonal pop.1lation statistics are listed in Table
E.3.134 for the lakes that had the highest scores.
The following discussions of individual waterbodies
are based on Kessel et al. {1982a).
E-3-379
4.2-Baseline Description
Stephan and MJ rder Lakes were among the top three
waterbodies in I.V. for all seasons. Stephan Lake
received twice as much use in fall as in spring~ and
supported high numbers of species and number of
birds. trltrder Lake consistently supported high
densities. These lakes assumed additional importance
in early spring and 1 ate fall because of ice
conditions. trltrder Lake~ which reportedly has some
open water all winter~ provided some of the first
open water for early spring migrants~ as did the
inlet of Stephan Lake; green-winged teal~ mallards~
and pintails were using this open water on May 3~
1981. Likewise, these lakes provided the last open
water in fall and were used by the late migrants.
Swans used these lakes during October, as other lakes
in the region became ice-covered. Between 9 and 11
trumpeter swans frequented M..lrder Lake between
October 10-18, 1981 (J. Ireland 1982 Personal
communication cited by Kessel et al. 1982a); 11 to 22
unidentified swans were on Stephan Lake from October
9-23~ 1981; and 120 swans were there on October 10~
1980.
WB 131~ near the mouth of the Maclaren River, consis-
tently supported high levels of waterfowl abundance,
density, and species richness. Its I.V. in spring
was 1 essened by the fact that it was sti 11 frozen
during the first two spring surveys. Because it was
far from the proposed construction sites, it was not
censused for breeding birds, but a flight over the
lake on August 4, 1981, revealed a flock of some 100
molting ducks, mostly scaup, as well as a pair of
trumpeter swans. This and WB 134 were the only duck-
molting lakes found in the basin. A flock of 22 to
42 trumpeter swans congregated to feed on this 1 ake
throughout the first half of September 1980.
WB 140, east of the Oshetna River, had the highest
I.V. of 28 waterbodies censused during the breeding
season. Not only did it have a high species richness
(11 species), but it also supported a large number of
birds and had an above-average density. It was also
of above-average importance during migration, even
though it thawed later and froze earlier than most
other lakes.
Clarence Lake had the fourth highest I. V. during
spring and fall migration, but ws less important
during the summer. It had a relatively high species
E-3-380
,,
~---
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-
4.2 -.Baseline Description
richness during all seasons, being used by both
diving and dabbling ducks during migration, but
primarily by divers in summer.
Watana lake was used in fall, especially in 1980, by
migrant scaup, go 1 deneyes, and mergansers during the
last half of September. Otherwise, it was of little
importance to birds.
Pistol lake in the 1 ower Deadman Creek area had a
relatively high I.V. in spring because of the number
and diversity of birds it contained after it began to
thaw toward the end of the first week of May. How-
ever, this relatively large lake was only of average
importance during summer, and was little used in
fall.
The southernmost Fog Lake supported high 1 evel s of
abundance and species richness during all seasons.
It received 1 ess use in spring than during other
seasons, probably because ice cover was still exten-
sive as 1 ate as May 17, 1981. On this date, ducks
were heavily concentrated in the open water at the
inlet end of the lake. This lake and WB 140 had the.
highest species richness (11 species) during summer.
WB 032, a small 1 ake at the west end of the Fog
lakes, supported a high density of birds in summer
and showed high productivity (at 1 east 4 broods of
horned grebe and 2 of American wigeon seen on July
28, 1981). It was not monitored during migration.
Swimming Bear Lake, an alpine lake, received its pri-
mary use during summer. After it thawed in 1 ate May,
it was occupied by at least 5 species of waterbirds
(scaup, oldsquaw, scoter, mew gull, and arctic tern),
3 of which were observed with broods on July 29,
1981. Flocks of scaup and white-winged seaters were
seen on the lake during the last half of September
1981.
None of the waterbod i es in the middle basin had
importance values as high as those calculated for
some of the better wetland sites of eastern interior
Alaska from data obtained during fall 1980 by Ritchie
and Hawkings {1981} (Figure E.3.106) and during
spring 1980 by Ritchie (1980) (Figure E.3.105).
E-3-381
4.2-Baseline Description
(iv) Lower Basin
The lower Susitna River above the delta appears to be
little used by waterbirds. Few birds were seen dur-
ing spring aerial surveys in either 1981 or 1982
{Table E.3.135), or during the June 1982 ground sur-
veys (see Appendix EF). Few birds have also been
seen on US Fish and Wildlife surveys (see King and
Conant 1981). Overall, swans, white-fronted goose,
scaup spp., common merganser and merganser spp. were
the most abundant species seen. NUmbers were highest
in the 1 ast 37 km of the river between the mouth of
Yentna River and Cook Inlet.
Ice on the lower river apparently broke a week or
more 1 ater in 1982 than in 1981. During the May 7,
1981, survey, the river above Talkeetna was breaking
up and carrying a heavy load of ice chunks; whereas
on May 10, 1982, this section of river was still
almost entirely frozen. Since spring migration of
dabbling ducks in central Alaska was only 2 to 3 days
later in 1982 than in 1981 (Kessel, unpublished
data), the main spring movement had passed through
the Susitna region in 1982 before water became avail-
able in the river above Talkeetna.
In addition to early season ice above Talkeetna, the
main reasons for the 1 ow use of the 1 ower river
appear to be its rapid flow and heavy silt load
(Kessel et al. 1982b). These factors limit the deve-
lorment of aquatic plants and associated inverte-
brates, the main diet of most waterbirds, and make
food invisible, except at shallow edges or in sloughs
(Kessel et al. 1982b). Corroborating this assumption
is the fact that the most numerous ducks on the river
were fish-eating mergansers (Kessel et al. 1982b}.
(c) Other Birds
(i} Shorebirds and Larids
Seven of the 19 species of shorebirds that occur in
the middle basin are transients that occur only dur-
ing migration (Appendix 3.E). An additional six
species nest in alpine tundra habitats that will be
little affected by the Susitna development. The six
species that will be most affected (semipalmated
plover, common snipe, spotted sandpiper, solitary
sandpiper, and greater yellowlegs) nest on alluvial
bars along the river edge or in lower elevation wood-
lands and meadows. No shorebirds overwinter in the
Su sitna region.
E-3-382
r:;.---,
-i
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( i i)
-
-
Five species of larids occurred in the middle basin
in 1980 and 1981 (Appendix 3.E) (Kessel et al.
1982a). Two are confirmed breeders in the area: mew
gull and Bonaparte•s gull. Mew gulls were the only
common larid species in the middle basin (Kessel et
al. 1982a), breeding around 1 akes and rivers. Arctic
terns and long-tailed j aeg ers were fairly common and
undoubtedly bred in the area (Kessel et al. 1982a).
Herring gulls were uncommon summer visitors (Kessel
et al . 1982a) .
Seven species of shorebirds were seen along the lower
Susitna River during a June ground survey in 1982 by
Kessel et al. (1982b) (Appendix 3.F). Spotted sand-
pipers were common breeders along shores of the main
river as well as along its sloughs and feeder creeks;
solitary sandpipers were also fairly common along the
river. Sernipalmated plovers were uncommon breeders
on alluvia, and greater yellowlegs were uncommon
probable breeders along the river. Winnowing common
snipe were recorded at numerous locations. Only one
migrant whirnbrel was observed on an alluvial island
bel ow Talkeetna, and tl'tQ female northern phalaropes
were also seen on the river.
Six species of 1 arids were recorded in the spring
1982 survey downstrean from Talkeetna (Kessel et al.
1982b). Herring gulls were most common with at least
7 breed·ing colonies in the lower basin; the largest
colony containing approximately 1300 birds (Kessel et
al. 1982b). Arctic terns and mew gulls were fairly
common breeders on river bars in isolated pairs and
small groups. Bonaparte• s gulls were fairly common
and probable nesters in spruce woodlands adjacent to
the river. Parasitic jaegers and black-legged kitti-
wakes were also recorded in the 1 ower reaches of the
river. Neither species breeds in the area (parasitic
j aegers breed in northv.est and northern coastal
Alaska, and the nearest black-legged kittiwake breed-
ing colony is located at Chisik Island in Lower Cook
In 1 et) •
Grouse and Ptarmigan
Spruce grouse are year-round residents of mixed and
coniferous forests in the middle Susitna Basin.
Their status was given as fairly common by Kessel et
a 1 . ( 1982a) W"lo reported a maximum density of 1. 0
territor ies/10 h a in white spruce-paper birch forest
in 1981 (Table £.3.136). Ruffed grouse were reported
as a rare vis it ant by Kessel et al (1982a) . Willow,
rock, and white-tailed ptarmigan were all recorded as
E-3-383
4.2-Baseline Description
breeders in the middle basin. Willow ptarmigan were
common in low shrub thickets and attained a maxirrum
breeding density of 0.5 territories/10 ha in
dwarf-low birch shrub (Table E.3.136) (Kessel et al.
1982a). Rock ptarmigan are also common in dwarf and
low shrub at high elevations and in blockfields and
also attained maxirrum breeding densities in dwarf-low
birch shrub (Table E.3.136) (Kessel et al. 1982a).
White-tailed ptarmigan were uncommon in dwarf shrub
mat and blockfields, and are found at generally
higher elevations than other ptarmigan, although
attitudinal ranges may overlap considerably with rock
ptarmigan (Kessel et al. 1982a).
Grouse and ptarmigan were not recorded along the
1 ower Su sitna River (Kessel et al. 1982b). However,
spruce grouse are 1 ikely residents of adjacent forest
habitats, and a few willow ptarmigan may migrate to
riparian habitats in some winters.
(iv) Woodpeckers and Passerines
In terms of numbers, woodpeckers and passeri nes com-
prise by far the greatest proportion of the birds in-
habiting the middle Su sitna Basin. Fifty-seven spe-
cies have been recorded, and nine (possibly 10) of
these are year-round residents (Appendix 3.E) All of
the woodpeckers and a large proportion of the passer-
ines are forest species, but passerines are found in
all vegetated habitats, from closed forest through
shrublands to alpine tundra. Breeding densities in
1981 and 1982 of these terrestrial species are given
in Tables E.3.136 and E.3.137, and are discussed in
more detail below.
The four species of swallow and the dipper are close-
ly associate with aquatic habitats, and they were not
adequately represented in censuses of terrestrial
habitats. Bank swallows _and cliff swallows nest
colonially, the former in cutbanks and the latter in
areas of cliffs and in abandoned cabins. Tree swal-
lows and violet-green swallows are not colonial and
nest in a variety of habitats. Swallows capture food
while flying over open expanses and often over lakes
and rivers, if they are present. The dipper is a
bird of clear, fast flowing streams. It forages
year-round in shallow sections of streams and hests
along streambanks and under bridges. Dippers are
uncoJ1111on in the middle basin, but a few birds occur
in each of the major creeks that drain into the
Susitna River as well as along the middle and upper
Susitna itself (B. Kessel 1982 pers. comm.).
E-3-384
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·~
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-
....
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4.2-Baseline Description
( v)
Thirty-nine species of woodpeckers and passerines
were recorded along the lower Susitna River during
the spring surveys. Six (possibly seven) are year-
round residents (Appendix 3.F). Relative abundance
of some species are discussed below.
Middle Basin Bird Communities
Breeding populations of terrestrial birds in the mid-
dle basin were studied in 1981 (Kessel et al. 1982a)
and in 1982 (Kessel, unpublished tables) by means of
plot censuses. The number of territories of each
species on the census plots in the two years is shown
in Table E.3.136 and E.3.137. Breeding bird densi-
ties in 1981 and 1982 are compared in Table E.3.138.
Table E.3.139 lists the avian habitats (as described
by Kessel 1979) represented in the 10 ha census plots
and their approximate equivalents in Viereck and
Dyrness (1980) vegetation types. Kessel et al.
(1982a) caution against the use of Viereck and
Dyrness types as avian habitat types because of: {1)
a failure to differentiate between habitats of medium
and tall shrub avian conurunities; and (2) a failure
to restrict coniferous and deciduous forest types to
exclusively (~90 percent) coniferous or deciduous
canopy coverage.
Density of breeding birds were substantially lower
in most habitats in 1981 and 1982 {Table E.3.138).
Kessel (1983 pers. comm.) believes that the 1981
densities were probably closer to normal and that
1982 densities were abnormally low, probably the low-
est since 1964. The low 1982 densities are attri-
buted by Kessel (1983 pers. comm.) to extremely late
environmental conditions relative to spring arrival
dates of migrants in 1982. At the suggestion of the
investigators (B. Kessel 1983 pers. comm.) the 1981
data is used ·in all analyses rather than a simple
average of the 2 years.
Generally, the forest and woodland habitats supported
higher densities of birds than the shrub comnunities.
Highest densities found in forests were at a cotton-
wood forest plot near Sherman, which supported 1. 7
bird territories/acre (60.9/10 ha). The lowest den-
sities in forest habitats were in the white spruce
forest plot at the mouth of Kosina Creek {0.6 terri-
tories/ acre [ 15.7 territories/ 10 ha]). Of the shrub
habitats, low-medium willow shrub had the highest
E-3-385
4.2-Baseline Description
densities (1.8 territories/acre [45.4 territories/10
ha]) and alpine tundra the lowest (0.2 territories/
acre [4.8 territories/10 ha]). Although alpine
tundra had the lowest bird usage, these types
supported some bird species generally not found in
other habitats, such as white-tailed ptarmigan,
horned lark, wheatear, water pipit, gray-crowned rosy
finch, and snow bunting.
Bird densities in habitats of the middle basin are
sim"il ar to those in the upper Tanana River Valley
(Spindler and Kessel 1980). In both regions, coni-
ferous forests were low-density habitats relative to
other forest types. Deciduous and mixed forests, and
shrubby woodlands in both regions supported inter-
mediate densities, and low shrub habitat support low
densities. Such differences in occupancy levels are
affected by a number of factors, inc 1 u ding in
Interior Alaska, habitat structural complexity and
primary productivity (Spindler and Kessel 1980).
Tall shrub habitats in interior Alaska support the
highest avian densities (Spindler and Kessel 1980).
Kessel et al. (1982a) attributed the lower densities
in their Susitna tall alder shrub study plot to
species composition of the shrub comrrunity. They
contrasted the average to above-average productivity
(Spindler and Kessel 1980) of the willow, thinleaf
alder (Alnus tenuifolia) and balsam poplar which
dominated the Tanana valley tall shrub plot with the
relatively low productivity of American green alder
(Alnus crispa) (Spindler and Kessel 1980) which domi-
nated in the middle Susitna Basin plot.
Kessel et al. (1982a) calculated Shannon-Weaver
diversity indices (H') for each census plot (Table
E.3.138). Diversity values are sometimes used as
indicators of habitat quality. Values of H • ranged
from 0.91 for the dwarf-low birch shrub plot in 1982
to 2.55 in the closed balsam poplar forest plot in
1981. With the exceptions of the white spruce forest
plot in both. years and white spruce woodland in 1982,
all plots in forest habitats obtained indices >2.0.
The tall alder shrub plot diversity index values were
2.05 in 1981 and 2.02 in 1982, while values in all
other shrub and tundra habitats were all <2.0. The 3
greatest diversity values in both years were obtained
in the balsam poplar forest, white spruce-paper birch
forest, and black spruce woodland plots (Table
E .3.138). The 1982 values on these more diverse
plots were substantially lower than 1981 index
values, the result of both reduced densities and
E-3-386
r----
F-..-,_
-
-
-
-
-
-
-
4.2 -Baseline Description
reduced numbers of species. Habitats obtaining high
values of H' are characterized by 1 arge numbers of
species and large numbers of individuals of each
species.
Each avian habitat type (as defined by Kessel 1979)
in the middle basin supports a moderately distinct
bird species association, as indicated in Table
E .3. 140.
(vi) Lower Susitna River Floodplain Bird Communities
Information on the relative abundance and habitat use
of terrestrial birds in the 1 ower Su sitna River
floodplain was obtained during a ground survey con-
ducted in June 1982 by the University of Alaska
Museum (Kessel et al. 1982b). Abundance was deter-
mined by counts of singing birds in each habitat
type. Total time spent in each of 10 habitats varied
between 30 and 352 minutes; data are presented as
birds per 100 minutes of survey in Table E.3.141.
Generally, following ecological tenets, both
abundance and species richness increased
progressively from the early to late vegetation
successional stages (Table E.3.141) (Kessel et al.
1982b).
Species composition of the early successional stages
was dominated by waterbirds, such as plovers, sand-
pipers, gulls, and terns. The only regular land bird
was the white-crowned sparrow, which was common in
medium-height shrub at the late stages of early suc-
cession (Kessel et al. 1982b).
Species composition and abundance in the tall shrub
and forest habitats of the lower Susitna River flood-
plain followed known patterns of habitat selection in
central Alaska, except in the cottonwood forests.
Several bird species normally associated with tall
shrub comrrunities (i.e., gray-cheeked thrush, black-
poll warbler, northern water-thrush and fox sparrow)
were found to select nesting territories within
riparian cottonwood forests, probably because these
forests have a well-developed, tall shrub understory
(Kessel et al. 1982b).
A profound effect of silt ground cover on avian abun-
dance was also noted along the lower floodplain.
Forest and tall shrub stands with a heavy ground
E-3-387
4.2-Baseline Description
cover of recently deposited silt were essentially
devoid of birdlife. Earlier studies (Spindler and
Kessel 1980; Kessel et al., unpublished data) have
suggested that there is 1 ittle preference by most
terrestrial birds for specific taxa of plant ground
cover, but apparently some kind of vegetative cover
is necessary--undoubtedly because of its role in
providing food resources (Kessel et al. 1982b).
4e2.4-Non-Game (Small) Mammals
Non-game (small) mammals of the project area include shrews,
voles, lemmings, red squirrels, ground squirrels, marmots, pikas,
snowshoe hares, and porcupines. Small mammals, by the nature of
their size and visibility, are not high profile species. How-
ever, they are important ecological components of most northern
ecosystems. Small rodents have been shown to be important in
nutrient cycling; soil aeration; dispersal of seeds, mycorhizae
and spores; control of insect pests; and as the primary or
secondary prey of many carnivores (Grodzinski and Wunder 1975).
Kessel et al.'s (1982a) studies of small mammals were restricted
to an area ranging 9e3 miles (15 km) to either side of the
Susitna River, extending from the Maclaren River on the east to
near Sherman on the west (approximately 6.2 miles (10 km) south
of Gold Creek). Within this area, 49 trapl ine transects were
established and operated in the falls of 1980-1982 and spring of
1981. Sites for the transects were se 1 ected to represent as
broad a spectrum as possible of the various vegetation types in
the region. Details on sampling techniques are provided in
Kessel et al. (1982a). Information on small mammals was also
obtained by opportunistic observationse
(a) Species Composition and Relative Abundance
During the study period, 16 species of small mammals were
trapped and/or observed in the middle basin (Appendix 3.G)
(Kessel et al. 1982a). In addition, there was evidence of
two other species occurring in the region: bats (two
separate sighti ngs of what were probably the 1 ittl e brown
bat) and water shrews (tracks of a small mammal between ice
openings on Watana Creek). The distribution of small mam-
mals documented in the middle basin is similar to known dis-
tributions in the literature. However, the occurrence of
arctic shrews in the study area constitutes a minor range
extension; the closest previous record was from Denali
National Park (Murie 1962).
The one s-pring and three fall trapline surveys involved a
total of 23,061 trap nights of effort (Table E.3.142).
E-3-388
~---
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4.2-Baseline Description
Totals of 950, 138, 2190, and 447 small mammal specimens
were captured during the fall of 1980, spring of 1981, fall
of 1981, and fall of 1982, respectively. A total of 1977
microtine rodents (6 species) and 1748 shrews (4 species)
was captured. Northern red-backed vales and masked shrews
were the two most abundant species of small mammals,
constituting 74 percent of the total captures. A total of
1458 northern red-backed vales and 1289 masked shrews was
captured during the 1980-82 studies. Other shrews captured
were arctic shrews (303 specimens), dusky shrews (146), and
pygmy shrews {10). Captures of microtines included 224
tundra voles, 103 meadow voles, 148 singing voles, 29 brown
lemmings, and 15 northern bog lemmings (Table E.3.142).
Capture results illustrate the large po!)Jlation fluctuations
that can be observed within and between years (Table
E.3.142). The fall 1980, spring 1981, and fall 1981
sequence demonstrates the typical annual cycle of most
short-lived irultiparous small mammals. In such species,
summer reproduction results in high po!)Jlation levels by
fall, and winter attrition reduces the po!)Jlation to animals
born late in the previous summer or fall. Superimposed on
this annual cycle are yearly fluctuations in abundance
demonstrated by the fall data for the 3 successive years.
The most common microtines, northern red-backed voles,
meadow voles and tundra voles, were most abundant in fall
1981, as was the most common shrew,the masked shrew. All of
these species exhibited very low fall po!)Jlations in 1982.
Fall 1982 capture rates were low for all species except
singing voles, brown lemmings, and bog lemmings, throughout
the study period. Northern red-backed voles were the most
frequently captured microtine in all periods. Masked shrews
were the most frequently captured shrew in all periods, in
spite of their dramatic .decline in abundance in 1982.
Six other species of small mammals were not trapped but were
observed in the study area by Kessel et al. (1982a): arctic
ground squirrel, hoary marmot, collared pika, red squirrel,
porcupine, and snowshoe hare. Although no quantitative
estimates of abundance were obtained for these species,
limited information on distribution was collected and is
reported below from Kessel et al. (1982a).
The arctic ground squirrel is a common and ecologically
important mammal of the region. The 1 argest numbers were
observed on the drier slopes, knolls, and ridges above tree-
line; only small numbers were observed at lower elevations.
General observations indicate that the Susitna study area
supports a relatively high and stable popjlation of ground
E-3-389
4.2-Baseline Description
squirrels, probably comparable to densities reported else-
where in the state (Kessel et al. 1982a). For example, ·in
the Talkeetna Mountains to the south, Hock and Cottini
(1966) removed 27 squirrels in one day from 0.12/acres
(0.05 ha) (22 squirrels/acre, 54/ha) with little apparent
decrease in numbers; the squirrel poJl,llation in this area
remained high throughout 4 years of study. In the eastern
Brooks Range, Bee and Hall (1956) counted 175 ground
squirrels along a 0.62 miles (1-km) ridge, and 70 squirrels
on approximately 3.7 acres (1.5 ha) of hillside (nearly 19
squirrels/acre, 47/ha).
Hoary marmots were locally common residents of the alpine
zone. Scattered colonies were found above treeline. None
were seen within the proposed impoundment areas. Collared
pika is another locally common alpine species, found on
talus slopes at higher elevations. No pikas were seen below
treeline. Densities of pikas in Denali National Park during
1962 varied from 2/acre (5/ha) in large rock s1 ides. to 10
acre (25 ha) on small, isolated rock pi 1 es (Broad books
1965).
Red squirrels, porcupines, and snowshoe hares were generally
confined to the forested areas of the basin. Red squirrels
were present in coniferous forests throughout the area, but
were most numerous in the mature spruce stands that occur
along the larger creeks such as Watana and Tsusena Creeks.
Porcupines are uncommon in the study area; a few individuals
were sighted during the summer of 1980, and 3 to 4 sets of
tracks were seen during the winter of 1980.
Snowshoe hares, a major source of food for predators over
much of central Alaska, were generally restricted to areas
east of Watana Creek. Localized 11 pockets 11 occurred
primarily in the vicinities of Jay Creek, Goose Creek, and
the lower Oshetna River. Snowshoe hare populations undergo
8-to 12-year cycles of abundance (Keith and Windberg 1978);
peak densities may be as high as 15.6 hares/acre (38.6/ha)
whereas densities may drop to as low as 0.05 hares/acre
(0.12/ha) during pop.llation lows (Green and Evans 1940).
Long-term information in overall hare abundance, provided by
several local residents, indicated that the recent low
number of hares is a chronic situation and not just a low
phase of the population cycle.
(b) Habitat Use
The following analysis of habitat use draws heavily from
Kessel et al. (1982a).
E-3-390
-
-
-
-
-
-
4.2-Baseline Description
(i) Shrews and Voles
Forty-two trapping sites were organized by Kessel et
al. (1982a) into floristically similar groups using a
cluster analysis of frequency counts of 81 plant taxa·
from the vicinity of the sample sites (Figure
E.3.107). The clustered subgroups roughly correspond
to the following vegetation types from Viereck and
Dyrness (1980}: sedge-grass and shrub tundra, sedge~
grass and low willow shrub, herbaceous-mixed low
shrub meadow, open white spruce forest, woodland
spruce, black spruce bog (some low birch shrub sites
were ·included in this group), paper birch-white
spruce forest, cottonwood forest, tall alder shrub,
and tall grass meadow. The number of captures of
each small mammal species relative to these vegeta-
tion types is shown ·in Figure E.3.108.
Shrews and red-backed voles in the middle basin dis-
played a relatively broad and uniform di stri but ion
pattern across habitats (Figure E.3.108). Masked
shrews, the numerically dominant shrew species,
occurred at all trapping sites. They were most
numerous in deciduous forest (particularly cotton-
wood), grassland, and tall shrub sites. Arctic
shrews occurred at 29 trapl ine sites, with peaks of
abundance on the drier, nonforested sites, particu-
larly grassland (at low elevations) and low shrub
(above treeline). Dusky shrews were thinly distri-
buted across the vegetation types of .the study area.
Although dusky shrews were captured at 23 sites, no
particular preferences were apparent; however, none
were captured in the wettest sites. The capture of
three pygmy shrews in cottonwood forest, one in white
spruce forest, and one ·in grassland during fall 1981
and the capture of five specimens in open spruce
forest and one in cottonwood forest during fall 1980
suggest a restriction of this species to forest
habitats. Northern red-backed voles, the dominant
microtine of the region, occurred on all but five
trapl ine sites. Northern red-backed voles were
moderately to very abundant in most forest and shrub
types. The greatest numbers were recorded in open
and woodland spruce and cottonwood forest sites. In
contrast, herbaceous meadows, particularly wet
meadows and paper birch forest, supported low numbers
of this species.
In contrast to the more general habitat occupancy
patterns of most shrews and red-backed voles, the 3
E-3-391
4.2-Baseline Description
Microtus species displayed stronger habitat specifi-
city, as evidenced by their general restriction to
open, nonforested sites (Figure E.3.108). Singing
voles were captured on only 10 trapl ine transects.
They were most abundant in open, 1 ow wi 11 ow-birch
shrub on relatively dry soils but were also found in
herbaceous tundra and mat and cushion tundra above
treeline. Tundra voles and meadow voles occurred
primarily in sedge and grass-forb meadows and bogs.
Tundra voles were captured on 22 sites (primarily
grass-forb,. but also sedge-grass), compared to 10
sites for meadow voles (primarily wet sedge-grass).
Small numbers of brown 1 ellllli ngs were captured on 11
sites at or above treeline, usually in wet herbaceous
and low shrub situations. Two bog lemmings were
taken at lower elevations in mesic sedge-grass/low
shrub meadow, one in grass meadow and one near a
seepage in white spruce forest.
To summarize the diffe'rences in habitat use among the
various species of small mammals, a standardized
habitat niche breadth measure was calculated for each
species captured dur·ing fall 1981 (Table E.3.143).
The ubiquitous masked shrews and red-backed voles had
the broadest habitat niche breadth, followed closely
by dusky shrews and arctic shrews. Microtus species,
particularly singing voles, had the narrowest habitat
niche breadths, along with the rare or uncommon pygmy
shrews, bog lemmings, and brown lemmings.
Small mammal community structures, especially as they
relate to species dominance and habitat breadth, are
highly correlated with pop.~lation levels and species
interactions. Because most northern microtine pop..~
lations undergo extreme fluctuations in density
(Krebs and Myers 1974), strict ecological boundaries
are difficult to delineate. A small mammal pop.~la
tion sampled during the peak phase of a pop.~lation
cycle may occupy a greater range of habitats than
during a pop.llation low. Interspecific competition
for space may a'l so vary with density. For example,
Kessel et al. {1982a) found that open herbaceous-
dominant habitats left vacant by declining Microtus
pop..~lations were quickly colonized and dominated by
the northern red-backed vole, suggesting that
Microtus species were able to exclude northern red-
backed voles from some habitats.
E-3-392
(<-'''·-,
r .
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4.2-Baseline Description
( i i)
Northern bog 1 emmi ngs and brown 1 emmi ngs were
uncommon members of the small mammal community in the
Susitna Basin. Bog lemmings are generally uncommon
throughout their range, and little is known of their
ecological requirements (Banfield 1974, West 1979,
MacDonald 1980). In other areas of the state, small
numbers have been taken primarily in shrub bogs and
marshes (Osgood 1900, Dice 1921, West 1979, MacDonald
1980)--not unlike the few sites where they occurred
during this study. Their diet is apparently restric-
ted to sedges, grasses, some forbs (Cowan and Guiguet
1956), and mosses (West 1979).
Although the high country of the middle basin has an
apparent abundance of suitable brown lemming habitat,
only small, scattered numbers were captured during
the 1980-81 study. However, they have been found in
fairly 1 arge numbers in other montane areas of cen-
tral Alaska (R. L. Rausch, Personal comrrunication
cited by Kessel et al. 1982a). The 1 ow numbers in
the Susitna area may be caused by a failure to sample
the right habitats, or, more likely, to sampling
during a period of low pollJlation levels. Brown
lemmings are usually associated with wet sedge-grass
tundra above treeline, but also are found locally at
lower elevations in spruce bogs and wet meadows
(Buckley and Libby 1957 and Banfield 1974). This
species is almost completely dependent on a diet of
sedges and grasses (Guthrie 1968), although mosses
may be important at times (West 1979).
Other Species
Arctic ground squirrels inhabit herbaceous tundra and
open shrub habitats above treeline (Kessel et al.
1982a). At lower elevations they also colonize
riverbanks, 1 akeshores, moraines, eskers, road si d-
ings, and other disturbed sites with subclimax vege-
tation (Guthrie 1968, Banfield 1974, Kessel et al.
1982a). Kessel et al.•s (1982a) observations corrob-
orate Bee and Hall 1 s (1956) conclusion for the Brooks
Range that the optimum conditions for ground squirrel
colonies are:
Loose permafrost-free soils on well-drained
slopes;
-Vantage points from which the surrounding terrain
can be observed; and
-Bare soil surrounded by vegetation in an early
xerosere stage of succession.
E-3-393
4.2-Baseline Description
Carl (1962) found that ground squirrels avoided sites
where tall vegetation (greater than 8 inches [>20
em]) impaired vision. The effects of squirrel acti-
vity--e.g., burrowing, mound building, feeding, feces
deposition--within areas of established colonies tend
to maintain vegetation at an early successional stage
(Carl 1962 and Youngman 1975).
During the snow-free months, ground squirrels provide
an abundant, reliable food source for a number of
mammal ian and avian predators (Carl 1962, Murie 1962,
Bente 1981, Olendorff 1976). At High Lake in 1981
the first ground squirrel emerged from hibernation
the third week of April; the latest date in 1981 on
which ground squirrels were seen was October 4 (E.
Powell, Personal com1111nication cited by Kessel et al.
1982a). These emergence and entrance dates are
essentially the same as those reported by Hock (1960)
and Hock and Cottini {1966) in the TaHeetna Moun-
tains near Anchorage, and by Carl {1962) at Ogotoruk
Creek, northwestern Alaska.
Hoary marmots and pikas are generally restricted to
tundra/talus habitats at high elevations (Hoffman et
a 1 • 1979 and Kesse 1 et a 1 • 1982a) • Both are ecotone
species: their homes and shelters are in one habitat
(rocks of various size and shape) and their food in
another (herbaceous tundra types) (Broadbooks 1965).
Hock and Cottini (1966) suggested that a portion of
their marmot population underwent seasonal shifts in
altitude, moving down from· high rocky slopes in fall
to sites having better conditions for winter denning
and having an available food supply in early spring.
An opposite seasonal movement apparently occurs in
some Montana hoary marmot colonies (Barash 1974).
The only suggestion of fall movement in the middle
basin was the observation of several marmot trails
and a single marmot traversing the 3500-foot-hi gh
{1067-m-high valley near Swimming Bear Lake (WB 150)
in about 3 inches (8 em) of snow on October 10, 1980
(T. Hobgood, Personal com1111nication cited by Kessel
et al. 1982a). Marmots hibernate longer than ground
squirrels; in the Talkeetna Mountains near Anchorage,
marmots emerge from hibernation during the first
third of May and begin entering hibernacula in early
September (Hock and Cottini 1966). Pikas are active
throughout the year (Sheldon 1930, Broadbooks 1965,
Hock and Cott in i 1966) and store 1 arge quantities of
dried plant material in late summer for use during
the winter months.
E-3-394
r· -,
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r-
i
....
4.2-Baseline Description
The arboreal red squirrel occupies a variety of
forest habitats, but prefers mature coniferous forest
(Cowan and Guiguet 1956). White spruce forest is
generally considered the optimal habitat in interior
Alaska (Nadler 1973). Red squirrels feed primarily
on the seeds of spruce, particularly white spruce,
but supplement their diet with fungi, fruits, and
even the buds of spruce and aspen (Smith 1967 and
Nadler 1973). They store large quantities of spruce
cones and mushrooms in middens for winter use (Murie
1927 and Streubel 1968). Buskirk (Personal comiTUni-
cat ion cited by Kessel et al. 1982a) noted that red
squirrel middens in the middle basin in fall 1981
appeared to be composed only of mushrooms and spruce
buds. A massive cone crop failure caused by an area-
wide epidemic of white spruce needle rust (Chrysomyxa
ledicola) during 1980 (J. H. McBeath, Personal comrru-
nication cited by Kessel et al. 1982a) may explain
why squirrels were storing such low-quality food as
spruce buds (Smith 1967). Smith ( 1967) reported a
67-percent drop in a red squirrel pop..~lation follow-
; ng the second year of a two-year cone crop failure
in white spruce forest and suggested that the
squirrels had emigrated into surrounding black spruce
stands. Repeated cone crop failures cou 1 d have
similar effects on red squirrels in the middle basin
(Kessel et al. 1982a).
In interior Alaska, Wolff (1977) found that snowshoe
hare habitat preference depended on pop..11 at ion den-
sity; during pop..~lation lows, hares were restricted
to dense black spruce forest and willow-alder
thickets, but during highs they used a wider variety
of vegetation types, including recently burned areas
with minimal cover. He concluded that a patchy
environment of recently burned sites with inclusions
of unburned spruce was the preferred hare habitat.
The chronic scarcity of snowshoe hares in the middle
basin is probably related to a scarcity of suitable
habitat (Kessel et al. 1982a). Recent burns and
riparian shrub thickets are noticeably absent from
this area (Kessel et al. 1982a).
E-3-395
4.3 Impacts
Five classes of impacts to terrestrial vertebrates are anticipated to
result from the Sus itna Hydroelectric Project: ( 1) permanent habitat
loss, including flooding of habitat and covering with gravel pads or
roads; (2) temporary habitat loss and habitat alteration resulting from
reclaimed and revegetated areas such as borrow areas, temporary rights
of way, transmission corridors, and from alteration of climate and
hydrology; (3) barriers, impediments, and hazards to movement; (4)
disturbance associated with project construction and operation; and (5)
increased human access not directly related to project activities. The
acceleration of secondary development in the basin is an indirect
impact which can be neither predicted nor controlled by the Alaska
Power Authority and is therefore excluded from this discussion.
Specific impact issues associated with each class of impact are
enumerated in separate tables and discussed in the following sections
for each big game and furbearer species.
Permanent loss of specific vegetation types is shown in Tables E.3.82
and E.3.83 for the Watana and Devil Canyon facilities. Approximate
time schedule and areas affected are shown in Table E.3.144 for perma-
nent habitat loss, temporary habitat loss, and habitat alteration.
Habitats a 1 tered by the t ransmi ss ion corridor and access roads are
described in Tables E.3.84, E.3.85, and E.3.86. Impacts resulting from
increased human access have already begun and wi 11 continue throughout
the life of the project.
4.3.1 -Watana Development
(a) Moose
Moose are common in the Susitna River valley and are one of
the most important wildlife species that will be affected by
the Watana project. Activities associated with the con-
struction of the Watana project will affect moose mostly in
areas adjacent to and within the dam and impoundment area.
Activities associated with the filling and operational pha-
ses will affect moose in both the middle and lower Susitna
basins. The construction and operation of the Devil Canyon
dam, access routes to the development sites, and transmi s-
sion lines also will affect moose in the Sustina Basin; im-
pacts resulting from these activities are discussed in
Section 4.3.2, 4.3.3 and 4.3.4. Although the Watana project
may benefit moose in some areas of the Susitna Basin,
detrimental effects of the project wi 11 likely result in a
decline in the number of moose and altered distributions of
this species throughout the basin. Because both migratory
and resident populations of moose utilize areas in the
immediate vicinity of the proposed impoundment area (ADF&G
1982a), impacts associ a ted with each phase of the project
could influence moose populations in other drainages removed
from the Susitna Basin.
E-3-396
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.....
....
I
-i
4.3 -Impacts -Watana Moose
In this discussion, impacts of the Susitna project on moose
will be assessed by estimating the extent (temporal and
spatial) to which carrying capacity for moose is reduced
within the basin, and by the effect on population regulatory
mechanisms (Figure E.3.109). The effects of developments
that reduce carrying capacity or productivity of moose popu-
lations for more than 10 years will be considered as severe
impacts. Moderate impacts may affect either a large propor-
tion of the moose population for a short period {less than
5 years) or a smaller proportion of the population for long
periods. Minor impacts will include very short term {less
than 1 year) effects. A summary of anticipated and hypo-
thesized impacts to moose appears in Table E.3.145.
The direct impacts that wi 11 niost severely affect moose pop-
ulations in the middle Susitna Basin are, in order of de-
creasing severity: permanent 1 oss of habitat, b 1 ockage of
seasonal migration routes, disturbance by machines and
humans, hazards associated with the drawdown zone, and
alteration of habitat. Moose in the lower basin will be
affected mostly by alteration of habitat. The major indi-
rect ~mpact of the Watana development will be the provision
of access to a previously remote area and a substantial
increase in hunting pressure with subsequent increases in
moose mort a 1 i ty.
ADF&G {1982a) estimated that about 2400 moose would have
home ranges that overlap a S-mile (8-km) zone surrounding
the impoundment area. The distance of 5 miles ( 8 km) was
derived by AOF&G (1982a) as 1/3 of the average moose home
range length and assumed that moose within this distance
would experience severe impacts. This estimate of 2400
moose was based on 162 radio-collared moose from an esti-
mated regional population of 4500 (total estimate for the
upper and middle Susitna basins). This estimate (2400 moose
severely affected) is biased by nonrandom sampling and is
undoubtedly high (see ADF&G 1982a for a discussion). How-
ever, it does provide a rough estimate of the number of
moose that may be affected by the project in the middle
basin without mitigation. The winter carrying capacity of
the impoundment zone, and areas lost to adjacent project
facilities was estimated to be 300 resident moose for 180
days (see Section 4.2.1[a]). This value is being refined to
account for movements of moose into and out of the area, and
to better estimate moose food requirements using simulation
modeling of moose bioenergetics.
The eventual fate of the moose having home ranges that over-
1 ap the 5 miles ( 8-km) zone around the Watana and Devil
Canyon projects is unknown; some would successfully disperse
to other parts of the Susitna basin or to adjacent drain-
ages; some would adapt to disturbances and remain in the
immediate vicinity of the impoundment until filling; and
£-3-397
4.3 -Impacts -Watana Moose
some would die as an indirect or direct result of the devel-
opment. Ongoing studies wi 11 greatly refine this assess-
ment.
(i) Construction
Construction of the Watana dam wi 11 involve intense
construction activities at the actual damsite,
estab 1 i shment of temporary camps and a permanent
townsite, remova 1 of forest cover in most parts of
the impoundment, and the excavation and transporta-
tion of borrow material. The major impacts on moose
during construction will be habitat loss or altera-
tion, disturbance, interference with seasonal move-
ments, and mortality associated with construction
activities and hunting.
-Habitat Loss
Clearing of the impoundment area, townsite, local
transportation corridors, and operation a 1 areas
will result in the permanent loss of some high
quality habitat for moose in the middle Susitna
Basin. (High quality habitats are those areas
supporting relatively high browse production and
having snow depths less than the regional average,
are~s where spring snowmelt occurs earliest, and/or
areas used for calving.) Campsites. borrow pits,
and construction access roads will temporarily ali-
enate smaller areas of habitat from moose use
(Tables E.3.143 and 144). There is no question
that moose will be affected by this loss of
habitat: browse availability will be reduced;
winter range, calving areas, and breeding areas
will be lost; movements may be altered as a result
of behavioral or physical barriers; animals will be
more vulnerable to predation and hunting (as a
result of the 1 oss of cover); and repeated human
and mechanical disturbances may preclude use of
some areas by moose. Accidental fires may also
temporarily eliminate moose habitat, although in
the long term would provide additiona1 areas of
high quality browse to moose.
Clearing of the impoundment area will remove a wide
range of riparian. deciduous forest, coniferous
forest, and muskeg communities which are important
to moose during all or part of the year. Although
moose may feed on the 1 eaves of felled deciduous
trees and some areas may develop sparse succes-
sional growth prior to flooding, inundation will
E-3-398
-
-
....
....
-
-
....
4.3 -Impacts -Watana Moose
eventually permanently destroy these habitats. The
distribution and occurrence of major plant communi~
ties in the Watana watershed are discussed in
Section 3.2.1. The regional availability of forest
cover types and their seasona 1 use by moose are
shown in Table E.3.146 •
• Winter Use
There is a genera 1 consensus that moose popul a-
tions in North America are ultimately limited by
the availability and quality of winter range
(Coady 1982}. High quality winter range of moose
is characterized by (1) abundant trees and shrubs
that are most preferred by moose as winter
browse; (2) consistently low snow depths in rela-
tion to surrounding areas, and (3} good inter-
spersion of young seral growth (for foraging) and
older aged forest stands (for cover) (LeResche et
al. 1974, Peek 1974}. The nutritional quality of
browse (e.g., amounts of crude protein, fats, and
carbohydrates; digestibility; total calories)
also is important in determining the quality of
winter range {01 demeyer 1974). Other factors
such as predation, hunting mortality, disease,
and weather may reduce moose populations bel ow
the carrying capacity of the range {Figure
E.3.109}.
Although the quality and quantity of winter range
are likely the limiting determinant for carrying
capacity of moose, they are critical to moose
survival only during severe winters. Winter
severity, particularly snow depth, strongly
influences the use of winter browse by moose
{Coady 1974, LeResche et al. 1974). During mild
winters, when snow depths are low throughout much
of the range, few moose may utilize critical
winter ranges. During severe winters, however,
deep snows may force high numbers of moose to
overwinter in limited areas. The limiting effect
of critical winter range may thus be evident only
during periods of severe winter conditions •
Although not observed during current moose
studies in the middle Susitna Basin (ADF&G
1982a}, earlier studies of moose in the basin
(USFWSF 1975, Ballard and Taylor 1980) suggest
that during severe winters with heavy snowfall,
moose move from upland shrublands to mixed spruce
deciduous woodlands at lower elevations. The
E-3-399
4.3 -Impacts -Watana Moose
Watana impoundment area includes several large
areas of river valley bottomland that are proba-
bly critical to survival of some moose during
severe winters. Mild winters with limited snow
cover during 1980 and 1981 are thought to have
resulted in the use of upland areas by moose in
the Susitna Basin and their absence from 1 ower
elevation sites. A census of the Watana impound-
ment on March 25, 1982 (a time when most moose
that used the impoundment area in that year would
be found there) determined that 260 moose were
present in the Watana impoundment area (ADF&G
unpublished data).
Because low elevation riparian shrub, deciduous
forest, coniferous forest, and muskeg habitats
will not be available in areas adjacent to the
impoundment, the removal of these habitats by
initial clearing activities and later flooding
will deprive moose of a large area of high quali-
ty winter range. Assuming that bottomland browse
resources throughout the middle Susitna Basin are
fully utilized by moose in severe winters, clear-
; ng and flooding of the impoundment wi 11 force
moose to depend on and likely over-utilize the
remaining winter range. Moose which never use
the impoundment area will also be affected by
over-utilization of these adjacent areas. In-
creased mortality would be expected caused by
starvation and increased predation, whereas
natality may decrease because of the poor
physical condition of moose •
• Spring Use
During recent moose studies (ADF&G 1982a), many
(no numbers available) of the radio-tagged ani-
mals moved to lower elevation habitats adjacent
to the Susitna River during late spring. It is
believed that these movements are related to the
earlier snowmelt and emergence of new plant
growth in low elevation sites (ADF&G 1982a).
Because moose typically have a negative energy
balance during winter and are in poor physiolo-
gical condition by late spring (Gasaway and Coady
1974), the availability of new plant growth may
be critical to survival. During the spring,
parturient cow moose commonly use low elevation
sites along the middle Susitna valley, presumably
to calve (no numbers given in ADF&G 1982a). The
E-3-400
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4.3 -Impacts -Watana Moose
availability of new plant growth and suitable
shrub cover in these low elevation sites .is
thought to be important to the survi va 1 of both
the cow and her calf. Bull moose and cow moose
without calves also utilize the low elevation
habitats during the spring (ADF&G 1982a).
Clearing and flooding of bottomland areas would
reduce availability of lower elevation sites
where spring snowmelt and plant emergence appears
to be more rapid. Because micro-climatic
changes resulting from the impoundment are sug-
gested to delay spring green-up by 5-15 days
(McKendrick et al. 1982) and because habitats
which will remain available around the impound-.
ment area are at higher elevations, moose may be
deprived of a large area of early spring habitat.
This impact would be most severe following
winters with deep snowfalls when moose may be
highly dependent on the availability of these
spring foraging areas.
ADF&G (1982a) suggest that concentrations of
calving moose occur in the impoundment area and
that these may represent traditional calving
sites (no unequivocal data are provided, see
ADF&G 1982a). Although it has not been shown
that moose use traditional calving areas (as do
several other species of ungulates), studies by
Markgren (1969) and Stringham {1974) suggest that
a calving location may be used repeatedly by an
individual cow. Predation moose calves by brown
bears is a major mortality factor of moose during
the spring and summer (Ballard et al. 1980), and
displacement of parturient cow moose from their
habitual calving areas by clearing activity may
increase the vul nerabi 1 ity of their calves to
predation •
• Summer and Fall Use
Because most moose in the middle Susitna Basin
commonly move to upland shrub habitats during
summer and fall, 1 oss of bottomland communities
will not have serious effects on summer and fall
habitat use. However, some sedentary (or non-
migratory) moose remain in the valley bottoms
throughout the year· and these individuals would
be displaced from their summer and fall range.
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4.3 -Impacts -Watana Moose
-Disturbance
During construction of the Watana dam and clearing
of the impoundment area, human and mechanical dis-
turbance will likely limit the use of several
development areas by moose and could result in
alterations in feeding behavior. Because undis-
turbed ungulates spend much of their active period
searching for and consuming food (Hudson 1977),
disruption of daily activities can reduce feeding
activity to the point where an i nd i vi dua 1 derives
less energy from the resources consumed than it
expends (Geist 1975). Ungulate energy balances are
most delicate during the winter (Dorrance et al.
1975, Moen 1976). Therefore, disturbances are
likely to have the most severe impacts on ungulates
during this season. An assessment of the effects
of disturbances on the energy ba 1 ance of moose in
the middle Susitna Basin and subsequent effects on
productivity is not possible on the basis of
current information, but will become feasible using
the modeling approach being developed (see Section
4.3.1(a)(iii).
Although repeated human and mechanical disturbances
could result in an alteration of activity budgets
with consequent impacts on growth, survival, and
production, a more serious immediate impact is the
alienation of some portions of the range as a
result of possible avoidance of human activity
areas. Prolonged avoidance would result in an
effective loss of habitat, and animals may concen-
trate in limited areas of prime range or subsist on
marginal range. Either scenario could result in
over-browsing and a reduction in carrying capacity
with eventual population declines (Sopuck et al.
1979).
Moose appear to be more tolerant of disturbances
than most ungulates (Tracy 1977), particularly if
disturbances are predictable, neutral stimuli such
as moving vehicles (Kucera 1976, Schultz and Bailey
1978). Cow-calf pairs generally respond to dis-
turbance more strongly than bulls and cows without
calves (Tracy 1977). If moose are not directly
approached by humans or machines, they appear to
tolerate even moderate and high activity levels.
For example, repeated aerial surveys of moose in
the vicinity of the Revelstoke Hydroeletric Project
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4.3 -Impacts -Watana Moose
in British Columbia over a five-year period that
spanned preconstruction and construction phases
indicated that moose numbers had not changed
despite frequent blasting and heavy industrial
activity {R. Bonar 1982 Personal Communication).
Observations of moose, including cows and calves,
in close proximity to active oil sands extraction
plants in northern Alberta despite frequent
mechanical disturbances and blasting, support this
observation {J. Green 1982 Personal Communication).
However, toleration of such activities by moose
appears to occur only in the absence of high levels
of human harassment and hunting. Moose can be
expected to avoid human activity areas if harass-
ment and/or hunting commonly occur.
Assuming that the Watana dam construction site and
associated facilities are restricted to as small an
area as possible and that hunting from project
facilities and harassment is prohibited, moose
would probably continue to utilize forested areas
near these sites. (Hunting has been prohibited
within a 10-mile corridor containing the
Trans-Alaska pipeline and can be regulated by the
Alaska Board of Game. Harassment is prohibited by
state law and can be minimized by adequate enforce-
ment.) If hunting from project facilities and
access routes is permitted, moose will avoid the
major activity centers, resulting in an additional
1 ass of habitat beyond that associ a ted with only
the impoundment and discrete construction areas.
Because the clearing of the impoundment wi 11 in-
volve noisy and unpredictable disturbances, moose
will probably avoid the areas of active clearing.
This and additional loss of habitat resulting from
a lack of cover in cleared sites will gradually
increase the intensity of use of browse in areas
outside the impoundment area during the
three-to-four-year clearing program. The concen-
tration of moose in these areas will increase
i ntraspeci fi c competition for food and space. If
the populations in these adjacent areas are at or
near carrying capacity, mor.tality of moose as a
result of starvation and predation may increase,
natality may decrease, and carrying capacity and
population productivity will gradually decline.
Aircraft enroute to or from the Watana airstrip may
cause minor disturbances to moose. In genera 1,
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4.3 -Impacts -Watana Moose
most aircraft are expected to maintain high alti-
tudes except during landing and take-off, and will
not be a major disturbance stimulus. Frequent,
low-altitude flights by fixed-wing aircraft or
helicopters may elicit panic responses in moose.
Because the intensity of reactions to aircraft by
ungulates is influenced by such factors as the time
of year; distance of the aircraft from the animals;
group size; sex and age composition; type of air-
craft; activity of the animals; and the type of
terrain (Sopuck et al. 1979), it is difficult to
generalize potential impacts on moose of repeated
aircraft disturbance. The use of wooded areas on
or in the immediate vicinity of several interna-
tional airports .in Canada suggests that if moose
are not harassed, they will habituate even to
frequent low altitude overflights (Green 1981).
-Interference With Seasonal Movements
Clearing of the impoundment area will not physical-
ly obstruct river crossings or seasonal movements
but may interfere with these movements through
avoidance of active clearing operations or the ex-
pansive clear-cut areas. Increased visual exposure
to predators and hunters may inhibit moose from
crossing these cleared areas. Several studies have
documented avoidance of large clear-cut areas by
moose (Hamilton and Drysdale 1975, Parker and
Morton 1978, Tomm 1978); in general, moose appear
reluctant to enter areas where they would be far
(i.e., more than (163-218 yards) 150-200 m from
forest cover. Following filling, the Watana
impoundment wi 11 constitute a greater obstacle to
seasonal movements of moose than did the river. A
more detailed discussion of the effects of the
Watana development on seasonal movements is
discussed below under Filling and Operation.
-Mort a 1 ity
An unpredictable number of moose may be killed as a
result of collisions with vehicles or other acci-
dents associated with construction activities.
Mortality to predators may also increase if
impoundment clearing facilitates hunting by wolves.
The effect, of these mort a 1 it i es on moose popul a-
tions is likely to be minor. The most serious
mortality factor associated with the construction
of the Watana dam wi 11 be the increase in hunting
associated with the influx of people into a previ-
ously remote area. Effects of increased hunting on
moose are described more fully in Section 4.3.3(a).
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4.3 -Impacts -Wata~a Moose
(ii) Filling and Operation
During the filling and operation phases of the watana
development, the major impacts to moose will be per-
manent loss of habitat, alteration of habitats
upstream and downstream from the damsite, blockage of
movements, disturbance, and increased accidents and
hunting mortality.
-Permanent Loss of Habitat
As flooding of the impoundment area proceeds, a
variety of bottomland and low elevation habitats
along the Susitna River will be permanently lost.
As discussed above for the construction phase of
the project, clearing of the impoundment area will
have already resulted in a substantial reduction of
the value of these areas to moose. By the time
these areas are flooded, few or no moose may be
utilizing these areas. However, the impoundment
will permanently alienate the area from moose use.
The consequences of the loss of these low elevation
areas have been discussed in the previous section.
As a result of the habitat loss, moose will be
forced into adjacent areas. Although it is not
possible to predict the distances moose will dis-
perse from the impoundment area, it is clear that
densities in adjacent areas will increase during
the clearing and filling of the impoundment.
Hunting guides in the vicinity of the W.A.C.
Bennett dam in northern British Columbia reported
an increased harvest of moose in areas near the
impoundment for a few years following flooding (K.
Child 1982 Personal Comrrunication). Increased
moose densities could result in a decline in habi-
tat quality in adjacent areas. If overutilization
of food resources, particularly winter browse
(generally conceded to be a major 1 imiting factor
in moose po!)Jlations) occurs, increased mortality
and decreased productivity can be anticipated.
During the operation of the Watana dam, a maxirrum
drawdown of 95 feet (29 m) will create an unvege-
tated shoreline zone that, in the Watana Creek
area, may be over 0.67 miles (1 km) wide. The
impoundment level will be at its highest in August
and September, and will generally decline between
E-3-405
4.3 -Impacts -l~atana Moose
October and August. Although a few herbs and forbs
may become established during early summer~ most of
the area wi 11 remain a bare rrud slope. Fine mate-
rial will gradually move downslope so that much of
the upper drawdown zone will eventually be composed
of coarser material. Except during crossings of
the reservoir~ it is unlikely that moose will uti-
1 ize the drawdown area. Hazards of the drawdown
area to moose movements are discussed below.
-Alteration of Habitats
The Watana Project will result in the alteration of
plant comrrunities in both the upstream and down-
stream Susitna Basins {Section 3.3). These altera-
tions will affect moose use of existing habitats
and may have some effects on the long-term produc-
tivity of populations •
• Upper Susitna Basin
Based on analyses of home ranges and seasonal
movements (ADF&G 1982a), radio-collared moose
commonly utilize lower elevation habitats in
close proximity to the future impoundments.
Vegetation in the areas immediately adjacent to
the impoundment may be altered as a result of
several mechanisms such as minor changes in
seasonal temperatures, wind direction and speed,
and ice fog preventing direct sunlight from
reaching the ground (see Section 3.3).
If the proposed reservoirs decrease either spring
daytime temperatures (Baxter and Glaude 1980) or
insolation, the spring green-up period may be
delayed. This phenomenon is complicated by the
fact that some plants use photoperiod rather than
temperature to trigger early spring growth (see
Section 3.3.1). If snow depths along the im-
poundment shoreline increase, plant green-up may
be delayed. Some parturient cow moose, as well
as male and young moose, were apparently observed
to move to lower elevation areas of the Susitna
River during the early spring~ presumably to
utilize the early emerging vegetation (ADF&G
1982a, no actual numbers available). Assuming
that the timing of the spring green-up is
important to the condition of parturient cows and
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4.3 -Impacts -Watana Moose
the survival of their calves, any delay in green-
up may reduce the survival of the calves. If
moose are forced to utilize higher elevation
areas where green-up is 1 ater (in comparison to
low elevation sites), a reservoir-'mediated delay
in green-up would further aggravate problems of
nutritional stress during the spring period.
Erosion of the impoundment shore will likely
occur during the period of maxirrum fill until the
new banks become stabilized. In particular,
permafrost slumping along the south shore of the
impoundment may eliminate large areas of habitat
along the shore, although most of the unstable
areas are steep slopes of 1 ittl e value as moose
habitat. Areas of successi anal vegetation,
favorable to moose, may develop on some of the
resulting more gently sloping areas along the
shores of the reservoir •
• Lower Susitna Basin
Changes in the flow regime will alter the avail-
ab·il ity and local distribution of important moose
habitat in the lower Susitna Basin. The extent
of vegetation changes will vary considerably
along the lower reaches of the Susitna River
because of the diluting effect of tributaries as
well as changing channel morphology (see Section
3.3.1). Differences between pre-and post-
project flow regimes wi 11 be greatest upstream
from Talkeetna; change in the frequency and dura-
tion of flooding, ice scouring events, and
shifting of bed materials will be less noticeable
as one progresses downstream.
The alteration of moose habitat in the reach
between Watana and Talkeetna can be better pre-
dicted than for areas further downstream. Be-
tween Watana· and Devil Canyon, the river is con-
tained by bedrock outcrops and steep canyon
sides; early successional vegetation favored by
moose occurs mostly on islands and along a narrow
band adjacent to the rna in channe 1 • The 1 ower
summer flows and lack of ice scouring will result
in the colonization of a narrow band by new vege-
tation and the succession of some areas now
subject to vegetative recession to climax forest.
Although moose habitat will be improved for 10 -
20 years, the lack of flooding and ice scouring
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4.3 -Impacts -Watana Moose
events wi 11 eventu a 11 y result in the dec rea sed
availability of good moose habitat along this
river reach.
In addition, preferred moose browse may become
unavailable in winter because of blockage of
movements by open water areas, and heavy frosting
of vegetation along this open water reach. The
icing effect is likely to be heaviest within the
steep canyon as it is downstream from the Peace
Canyon dam in British Columbia (where the climate
and topography is similar) {Movold 1982 Personal
Communication). In most areas, icing is unlikely
to reduce brouse availability, but it will
increase the energy requirements of moose which
consume large quantities of ice.
During o per at ion, the a rea in the De vi 1 Canyon-
Talkeetna reach supporting early successional
plant cormunities will be regulated by flow dis-
charge from Watana at freezeup (see Section
3. 3. 1}. Higher post-project winter flows wi 11
initially cause a widening of the unvegetated
floodplain, including a decrease in the size of
islands. If flows at freezeu p are kept constant
each year, little browse would be available to
moose at any time of the year. However, flows at
breakup are varied to meet energy demand or a
reservoir level rule curve, the early succes-
sional stands will appear as plants colonize the
scoured areas above the winter ice stage.
Female moose in the area north of Talkeetna
appeared to move to and use riparian habitats and
river islands during the calving period (ADF&G
1982b). Islands appeared to be particularly good
calving areas, perhaps as a result of lower
numbers of predators {Stringham 1974). Stable
winter flow release will cause a decrease in the
amount of early-successional vegetation in this
reach, thereby degrading calving habitat. Most
river islands will decrease in size, thus provi-
ding fewer areas for calving. If any islands
become connected to the river banks, their value
as calving areas will be further decreased.
The effects of the project on the quantity and
quality of moose browse downstream from Talkeetna
will be less than those between Devil Canyon and
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4.3 -Impacts -Watana Moose
Talkeetna, but because the number of moose using
th~ river increases as one moves downstream, smal
sma 11 effects on vegetation cou 1 d resu 1t in re 1 a-
tively greater effects on moose. In winters of
deep snowfall (such as in 1982-83), the amount of
browse available above the snow surface probably
1 imi ts the moose pol)ll at ion, and in these
winters, a decrease inavailability of brouse can
be translated to a proportional change in the
moose pol)ll at ion supported along the river. In
most winters, however, the amount of riparian
vegetation does not limit the pol)llation (Section
4.2.1[a]), and changes in browse availabiity
would be less important.
As discussed in Section 3.3.1(a), the area colo-
nized by early-and mid-successional vegetation
will vary considerably during the license period
depending on the timing of peak floods of the
various tributaries and river stage at freezeup.
Additional research is ·in progress to improve the
ability to predict future trends in the quantity
and quality of moose browse based on an under-
standing of bank erosion processes, the
importance of ice scouring in vegetative reces-
sion, and colonization rates on different
substrate types •
-Blockage of Movements
Studies of seasona 1 movements of moose in the
middle basin have identified several sites along
the river where moose crossings tended to be con-
centrated (ADF&G 1982a). Depending on the time of
year, moose attempting to cross the impoundment
would encounter open water or uncertain ice condi-
tions. Drifted snow near the southeast end of the
impoundment cou 1 d physically prevent moose from
crossing the impoundment at that location. Because
all of the recorded moose crossings of the Susitna
River during 1980-81 occurred during May to
November, moose wi 11 most commonly encounter open-
water conditions. In addition, these animals would
have to descend over mud flats or ice blocks within
the drawdown area. Percentage slopes of the draw-
down area in the Watana impoundment will range from
less than 5 percent to as high as 115 percent
(Hanscom and Osterkamp 1980). As a result of both
the physical and visual barrier effects of the
impoundment, it is likely that some moose movements
will be blocked by the impoundment.
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4.3 -Impacts -Watana Moose
Moose in British Columbia apparently do not seem to
cross the open river area bel ow dams in winter
(Harper 1982 Personal Comrrunication). The stretch
of open river between Watana and Devil Canyon
during winter will interfere with moose crossings
during that season.
Moose in Alaska are adapted to and are dependent on
seral habitats in at least a portion of their sea-
sonal range (LeResche et al. 1974). With the
exception of riparian zones, which are seral commu-
nities with predictable locations, most
successional comrrunities are products of random
events such as forest fires, slides, or storms. To
utilize new successional areas, moose must maintain
some degree of flexibility in their seasonal and
regional movement patterns. It is probable then
that surviving moose in the vicinity of the
impoundment will alter seasonal movements and cros-
sings to maximize use of the remaining browse and
forage supplies.
Blockage of seasonal movements, particularly to
winter ranges or to calving areas, could severely
affect moose poJX.tlations if no alternative ranges
are available. Moose distributions during 1980
suggested that relatively high concentrations of
moose overwintered on both sides of the proposed
impoundment. Locations of moose during the calving
period similarly suggested that although moose were
located more often to the north of the impoundment,
animals probably calved on both sides of the
impoundment. Relocations of moose during 1981-82
suggest that, although some moose cross the Susitna
River to winter or calve, suitable habitat for
calving and wintering are available on both sides
of the valley. However, there is one report that
moose have been known to starve to death in a tra-
ditional foraging area, even though adequate
habitat was present nearby (W. Ballard 1982
Personal Communication).
Additional information on the availability of cri-
tical winter range and calving habitats following
flooding is being obtained to more accurately
assess the impacts of interference with seasonal
movements.
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4.3 -Impacts -Watana Moose
-Disturbance
Mechanical and human disturbance should decline in
the impoundment and construction areas once the
Watana dam is operational. Public access will
continue to increase levels of disturbance, though
at a level lower than during construction.
Helicopter and boat trips to the Jay Creek mineral
lick by project personnel and recreationists would
have an insignificant effect on moose. If animals
are not directly harassed, disturbances during the
filling and operation stages, with the exception of
hunting, will at most have a slight effect on moose
distributions.
-Mortality
During the filling and operational phases of the
Watana project, hunting mortality of moose may be
much greater than current 1 evel s. Construction
workers may hunt, and improved access wi 11 permit
hunters to reach many more areas within the Susitna
Basin. Hunting pressure will likely increase
rapidly during the first five to ten years of the
project, and increased harvest of moose is ex-
pected. Hunting will prevent over-brousing of
remaining range by removing displaced animals
(assuming adjacent areas would be over-utilized as
a result of moose dispersal from the impoundment
a rea).
Mortality of moose may result from animals being
injured on ice shelves, falling through the ice
after the water 1 evel has been drawn down (Harper
1982 Personal Communication), or from animals
becoming mired in the drawdown area. Moose have
also become trapped and drowned in floating debris
within impoundments (Child 1982 Personal Communica-
tion). Floating ice during breakup may cause
similar increases in crossing mortality. The
number of moose accidentally killed each year as a
result of the impoundment hazards, based on experi-
ence from impoundments in British Columbia (Bonar,
Harper, Childs 1982 Personal Communication) is
unlikely to exceed one percent of the moose popula-
tion occurring within five miles of the impound-
ment. However, highway and railroad kills
associated with the project may be substantial (see
Section 4.3.3[a]).
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4.3 -Impacts -Watana Moose
The impoundment will also affect predation rates on
moose. The ratio of brown bear to moose may
increase in the early years of filling and
operation. Bears may also kill more moose to
compensate for the loss of vegetation in spring.
The drawdown zone and ice conditions may facilitate
hunting of moose by wolves. If a severe winter
occurs during or just after filling, the moose
population may suffer high winter mortality,
reducing its ability to sustain high levels of
predation. These factors could allow predation to
drive the moose population to low levels, with slow
recovery because of sustained predation levels.
(iii) Quantification of Project Effects
The loss or alteration of moose habitat in the middle
basin during both winter and summer has been identi-
fied as the major impact of the project on moose.
The population-based studies conducted to date indi-
cate the magnitude of use of areas by the existing
populations during the study, but do not allow a
quantitative assessment of the potential of the
habitat to support moose under varying environmental
conditions. To estimate moose carrying capacity in
the Susitna project area, a moose bioenergetics model
is being developed. This habitat-based assessment,
in combination with the population-based assessment
currently underway, should provide a strong basis for
impact prediction and mitigation planning.
Carrying capacity models based upon the nutrient
requirements of the anima 1 and the capacity of the
range to supply these necessary nutrients have
recently been developed (Moen 1973, Wallmo et al.
1977, Mautz 1978). The nutritional interfaces
between the anima 1 and range are forage selection,
ingestion, and digestion. Forage quality can be
assessed by measuring ava i 1 ab 1 e nitrogen and energy.
Other nutritional entities are requisite to the
health of wild ungulates, but they are seldom the
limiting factor.· A simulation model of ruminant
energy and nitrogen balance developed by D. M. Swift
(1983) and Swift et al. (1981) has been adapted to
moose (Regelin et al. 1981) Schwartz and Franzmann
1981b). This model predicts rates of daily forage
intake and changes in body weight and composition of
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4.3 -Impacts -Watana Moose
an individual moose based upon the composition and
quality of ingested forage. The basic research
necessary to adapt the model to moose was conducted
at the Moose Research Center near Soldotna, Alaska,
during the past five years. Required information to
adapt the model to moose included moose energy and
protein requirements, digestive capacity, rumen turn-
over time, rate of passage, and partitioning of
energy from gross energy intake to net energy avail-
able for production (Regelin 1982 Personal
Communication).
The model estimates daily energy and nitrogen re-
quirements for non-reproducing moose. Based on daily
diet digestibility and nitrogen concentration, the
model predicts total voluntary intake; rates of di-
gestion and passage; partitioning of energy and
nitrogen to maintenance, growth and fattening;
changes in 1 ean body mass and adipose reserves; and
returns of energy and nitrogen to the ecosystem
(Swift et al. 1983). Specific information on the
range nutrient supply must be col 1 ected from each
area where carrying capacity is to be predicted. The
data needs are the amount of available forage, quali-
ty of the forage, and food habits of moose. The data
are first used in the ruminant sub-model to predict
daily intake rates. A separate model then estimates
the potential carrying capacity of the area. The
total amount of digestible energy and crude protein
available to moose is calculated. The carrying capa-
city is determined by dividing the daily requirements
for digestible energy and crude protein into the
total amount available. Separate estimates are made,
based upon crude protein and digestible energy.
Carrying capacity can be expressed as the number of
moose days of use or the number of moose~ and can be
predicted for summer or winter periods.
The ruminant sub-model has been adapted to moose and
produces realistic outputs; however, the model has
not been validated under field conditions. There are
currently plans to validate the model using moose
within four 1-mi 2 pens at the Kenai Moose Range.
Potential carrying capacity will be predicted in each
enclosure, and each wi 11 be stocked with moose at
different densities. The moose will be weighed peri-
odically to determine if the sub-model correctly pre-
dicts changes in body weight.
Specific data needed to quantify the carrying capaci-
ty of moose within the middle basin are listed below
(Regelin 1982 Personal Communication):
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4.3 -Impacts -Watana Caribou
(b) Caribou
-Detailed vegetation maps of the Watana impoundment
area and middle basin. The areal extent of each
vegetation type must be calculated and the spatial
distribution of each type must be determined.
-Standing crop bi amass of moose forage within each
vegetation type must be determined through appro-
priate sampling methods.
-Food habits of moose during October, February, May,
and July need to be determined. Fresh fecal
pellets should be collected at each season and
analyzed by the microhistological technique to
determine food habits.
-Seasonal nutritional quality of moose forage needs
to be measured. Important forage species ( 4-6
species) should be collected during October,
February, May and July. Only plant parts eaten
should be collected from several locations within
the area. Samples should be ground in a Wiley mill
and analyzed for N content and in vitro digestibil-
ity. Moose rumen fluid should be utilized in the
in vitro digestion process.
Nonhabitat related impacts such as increased preda-
tion or crossing mortality will also be assessed
through the use of simulation modeling. Various
levels of predation or other mortality will be input
to the model now being developed to assess the
resulting long-term effect on the population. Pre-
1 imi nary outputs from these ana lyses wi 11 be
available in 1983, but the combined effects of habi-
tat 1 ass and alteration and various direct mortality
factors will not be available until 1986.
Anticipated and hypothesized impacts to caribou are summa-
rized in Table E.3.147. Alaska's Nelchina caribou herd is
an invaluable wildlife resource and may be subject to
serious impacts as a result of the Watana project. In
particular, concerns have focused on the position of the
impoundment in a migratory corridor. Direct impacts here
treated include blockage of migratory routes, hazards
associated with impoundment crossings. disturbance, and loss
of habitat. Increased access will be a major indirect
impact.
E-3-414
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4.3 -Impacts -Watana Caribou
(i) Construction
Construction activities in the immediate vicinity of
the Watana dam are unlikely to greatly affect caribou
of the Nelchina herd.
The construction site will remove much 1 ess than one
percent of infrequently used habitat. Although some
caribou may ;encounter and avoid areas of intensive
human activity, this should not result in any popula-
tion effects. Proposed borrow sites also cover less
than one tenth of one percent of caribou habitat and
are temporary facilities. Borrow sites A, 0, and F
are more likely to be frequented by caribou than are
the other potential borrow sites. Most use of these
areas is attributable to summer use by bulls, and it
is unlikely that the cow/calf segment of the main
Nelchina herd will come close to the borrow sites
during annual movements. Although. bull caribou
appear to be less sensitive to human activity and
disturbance than other portions of the herd, they may
still avoid the areas during active mining to a limi-
ted extent. As a result, the borrow sites will re-
present an inconsequential loss of summer bull habi-
tat. Caribou may avoid the construction camps and
permanent vi 11 ages, but again these areas remove a
relatively small area of infrequently used habitat.
Aircraft traffic will increase considerably in the
middle basin as a result of the project. The degree
of response of caribou to aircraft disturbance
depends on many factors, including: aircraft type,
altitude and horizontal distance from the animals,
season, group size and composition, previous
activity, herd experience and habitat type. There is
some evidence that aircraft disturbance could result
directly in the death of young animals (DeVos 1960,
Miller and Broughton 1973). However, no unequivocal
evidence of this for wild animals is available, and
except for intentional harassment of animals by air-
craft or low-altitude flights causing groups of
animals to stampede, the main concern of aircraft
harassment is related to its energetic effects.
Caribou and other large mammals often react to a
low-flying aircraft by running. The energetic cost
of running in caribou can be 8 to 20 times the basal
metabolism (Geist 1975), and there is some evidence
that the energy costs to animals that show no overt
response at all to disturbance are nevertheless
increased (e.g., MacArthur et al. 1979).
E-3-415
4.3 -Impacts -Watana Caribou
Most studies have found that fixed-wing aircraft are
less disturbing than helicopters, other factors being
equal (Klein 1974, McCourt et al. 1974, Surrendi and
DeBock 1976, Fischer et al. 1977, Miller and Gunn
1979), although horizontal and vertical (altitude)
distances have not always been distinguished. Shank
(1979) generalized results of all these studies and
suggested that response levels decreased rapidly with
increasing distance from the aircraft up to distances
of about 250 feet (80 m). Beyond 250 feet (80 m),
response levels decreased more slowly, and there was
great variability in the level of response at parti-
cular altitudes. The results of both Fischer et al.
(1977) and Miller and Gunn (1979} suggest that re-
sponse levels decrease with increasing horizontal
distance in a much more regular manner than the de-
crease in response with decreasing vertical distance.
From the various studies that have beeri conducted on
large mammals, and by extrapolating from the domestic
reindeer literature (Zhigunov 1968, Klein 1971), it
is evident that very high levels of disturbance from
1 ow-flying aircr-aft could affect the productivity of
caribou; however, if pilots maintain an altitude of
at least 1000 feet {300 m) above sound level whenever
possible 2000 feet {600 m) agl over the calving
grounds during April-July), there is little evidence
to suggest that caribou would be seriously affected
by aircraft associ a ted with project construction and
operation.
(ii} Filling and Operation
the area to be flooded by both the Watana and Devi 1
Canyon impoundments represents much less than one
percent of the Nelchina herd•s range (ADF&G 1982c).
Skoog (1968) considered the middle Susitna bottomland
to be low quality grazing habitat, but noted its
importance to migrating animals at several times of
the year. The loss of caribou habitat as a result of
inundation wi 11, therefore, not be of major conse-
quence to the herd, and by itself should not cause
any change in herd size, productivity, or distribu-
tion patterns.
Information co 11 ected on the movements of the
Nelchina caribou herd since 1947 indicate that the
proposed Watana impoundment would intersect a major
caribou migration route. This has led to concerns
that the impoundment and other project faciliti~s
might serve as barriers to caribou movements, cause a
decrease in use of portions of the range, increase
the mortality rate, and tend to isolate one or more
E-3-416
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4. 3 -Impacts -Watana Caribou
subherds having separate calving grounds. Many
secondary impacts, whose probability would be even
more difficult to predict, would follow, including
increases in predator po pul at ions which would further
increase mortality, decreases in the birth rate and
in calf survival, and decreased potential carrying
capacity because of alienation from use of some por-
t ions of the range.
Hov..ev er, 1 arge movffilents of caribou across either of
the proposed impoundment areas have been reported
only once si nee 1973 ( skoog 1968, ADF&G 1982c).
Hemming (1971) reported that, as the herd increased
in size between 1947 and 1962, shifts in range use
and seasonal splitting both increased in frequency,
and the herd expanded its range. Conversely, as
numbers decreased after 1962, the area occupied by
the herd contracted toward the traditional cal·.;ing
area in the Talkeetna MJuntains.
It thus appears that there is a c 1 ose rel at ionshi p
between herd size and the potential for adverse
impacts caused by the Su sitna Hyd roel ect ric Project.
As the herd increases, large movffilents of caribou
across the Watana impoundment and Oenal i to Watana
access road will likely recur. However, major move-
ments across these facilities are not expected under
the current Nelchina caribou managffilent plan (ADF&G
1976), which includes a managffilent guideline to har-
vest the annual increment after the herd reaches
20,000 adult caribou. Herd mov6llents. during the
construction phase are not likely to differ greatly
from those observed during the past five years, since
herd size is not likely to exceed 30,000 caribou
before 1990.
It is not possible to determine to what extent, if
any, portions of the historically used range would
become alienated from regular use by the impoundment.
It is possible that isolated subherds with separate
calving grounds would regularly utilize those por-
tions of the range. It is also possible that no
decrease in use will be detected (although mortali-
ties related to impoundment crossing will occur). If
portions of the range are alienated from regular use,
the project wi 11 result in a decrease in the ability
of the range to support population levels M'Jich have
occurred in the past. Although current managanent
plans call for maintenance of the herd at 20,000
E-3-416A
4.3 -Impacts -Watana Caribou
adults, the option to allow a substantial increase
may be foreclosed by development. Again, it is not
possible to determine the value of this hypothetical
upper limit at the present time or how much it may be
reduced by the project.
Even at current herd size, the Watana reservoir will
interfere with the migration of caribou between por-
tions of the herd's range and may increase mortality
during migration as a result of hazards created by
the impoundment. Although the large movements of
caribou recorded in the past across the proposed
Watana impoundment area have not occurred in recent
years, the area is still used by many caribou as a
travel route. Nine crossings of the prop:Jsed
impoundment by six radio-collared caribou were
documented during studies in 1980 and 1981, and other
caribou apparently walked along the river ice between
the Tyone and Oshetna Rivers area to Kosina Creek and
Watana Lake, where they then moved into the Talkeetna
Mountain foothills.
Crossings of the impoundment in 1980 and 1981
occurred most 1 y between April 10 and May 31, and
between August 1 and September 30 (ADF&G 1982c).
About 10 percent of the main herd crossed the river
during Q:tober 1982 (Pitcher 1982 Personal Communica-
tion) . The annual drawd own of the reservoir in
winter will result in the impoundment being at its
lowest level at the time of the spring migration, in
late April and early May. At this low point, the
impoundment will average approximately 95 feet (29m)
1 ower than when it is full in October. The gradual
winter drav.down will result in the formation of ice
blocks grounded on the shore. Where the slopes of
the shoreline are gradual, such as along the Watana
Creek drainage, the blocks will be wide and flat and
more easily traversed. Where the banks are steeper,
the ice will be fractured into smaller blocks and
pile up as ice moves up from below and slides down
from above; these areas may be more d iffi cult for
caribou to cross. It is possible that some caribou
may be killed or seriously injured when crossing.
During the ice-covered reservoir period, the prevail-
ing northeast winds will tend to sweep the reservoir
clear of snow or at least will maintain a smooth,
flat surface. Drifting snow is thus expected to
accunul ate near the southwest end of the reservoir.
E-3-4168
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4.3 -Impacts -Watana Oall Sheep
(c)
proceeding to the least likely reaction (Banfield
1982 Personal Communication; Roseneau 1982 Personal
Communication). In any particular year, all four
responses will likely be exhibited by varying propor-
tions of the herd.
-The caribou wi 11 manage to cross the impoundment
safely in the Watana and Kosina creek areas.
-The caribou will travel eastward and cross the
Susitna River in the vicinity of the Oshetna and
Tyone rivers on ice-covered flats.
The caribou will make hazardous crossings with
increased mortality.
-The caribou wi 11 refuse to cross the impoundment
and reverse direction.
The Watana impoundment should not cause any substan-
tial caribou mortality during the summer and fall
open-water period, but it may greatly influence the
movements of some caribou during that time. Caribou
are excellent swimmers, but large lakes and swift
rivers can change the direction or timing of move-
ments. Skoog (1968) reported that ,.even though
caribou are excellent swimmers and generally take
readily to the water, frequently I have noted how a
movement wi 11 change direction upon encountering a
large lake or river and will parallel the waterway
rather than cross it ... Banfield and Jakimchuk (1980)
ADF&G 1982c) state that 11 Caribou prefer to avoid open
water, 11 and that 1 arge 1 akes are often crossed at
narrow points or where islands provide interim
stopping points. It thus seems likely that caribou
approaching the reservoir in the Watana Creek vi ci-
nity, for example, might parallel the shore to an
area where the impoundment is narrower.
Oall Sheep
Anticipated and hytopthesized impacts to Oall sheep are
summarized in Table E.3.148. The most serious impacts to
Dall sheep include disturbance and harassment and the inun-
dation of portions of a mineral lick. Disturbance of sheep
at the lick is a major potential impact.
(i) Construction
E-3-417
4.3 -Impacts -Watana Dall Sheep
The three Dall sheep populations identified in the
Susitna Basin are most likely to be affected by the
project through disturbance (i.e., aircraft traffic,
construction noise, presence of workers), habitat
1 ass, and increased access by hunters. Each of the
populations will be affected to a different degree as
a result of their distribution in relation to project
facilities.
The Mount Watana population does not usually occur
near the impoundments, access roads, or borrow areas
at any time of the year, and is likely to be affected
only by lo·w-flying aircraft crossing between the
Susitna and Talkeetna river drainages. Disturbance
from low-flying aircraft is also of concern with the
Portage-Tsusena Creek population. The Watana Hi 11 s
population will be most affected by the project
because of the partial inundation of a major mineral
lick on Jay Creek used by this population. As will
be discussed, the frequent disturbance of sheep at
the lick by project personnel and recreationists is
expected to be a more immediate and serious impact
than will the eventual partial inundation of the
1 i ck.
The impact of intensified human activity on Dall
sheep populations is not completely understood, but
some general predictions can be made. If an animal
is excessively aroused, as from human disturbance,
the added cost of excitement or activity may inter-
fere with health, growth, and reproductive fitness
(Geist 1975). Ewes with lambs are particularly
sensitive to disturbances {Smith 1954, Jones et al.
1963). Recent studies of free-rangin9 ungulates have
fauna that the heart rate of an 1ndividual is a
sensitive indicator of arousal, the first stage of an
alarm reaction to stress (Ward et al. 1976; MacArthur
et al. 1979, 1982). These and other investigators
have demonstrated consistent heart rate responses to
disturbing visual or auditory stimuli, often in the
absence of overt behavioral reactions. MacArthur et
a 1. ( 1982) reported on the heart rate response of an
unhunted population of mountain sheep (Ovis
canadensis) to aircraft and vehicle traffic. ~
heart rate responses were associated with helicopter
or fixed-wing aircraft at distances exceeding 1300
feet (400 m) from sheep. They found that direct
overflights at 100-275 feet (90-250 m) by helicopters
caused sheep to run for 2-15 seconds and elicited a
E-3-418
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4. 3 -Impacts -Watana Da 11 Sheep
2-3.5 x increase in heart rate. In Alaska, six
studies have included observations on the response of
Dall sheep to aircraft disturbances (Andersen 1971,
Linderman 1972, Nichols 1972, Price 1972, Lenarz
1974, and Summerfield 1974), although only one of
these (Lenarz 1974) presented quantitative data.
Helicopters usually evoked a greater response from
sheep than did fixed-wing aircraft. This is possibly
because helicopters fly slower and closer to the
sheep and are generally more noisiest (especially
"rotor popping") (Andersen 1971, Linderman 1972,
Price 1972). No studies have been conducted to
determine the responses of mountain sheep to aircraft
flying at different altitudes, as have been conducted
with caribou and muskoxen. The reaction of Dall
sheep to low-flying aircraft is highly variable
(Linderman 1972 and Price 1972), although Linderman
found that sheep always reacted nervously and assumed
the alarm posture {Geist 1971b) until the disturbance
had passed. Lenarz (1974) found that 11 ewes 11
{including young rams not discernible from females)
reacted more strongly to helicopters than did rams.
Andersen {1971) and Price {1972) found that sheep
were more easily disturbed by aircraft when congre-
gated at mineral licks, which are usually located
lower on slopes away from escape cover.
The Watana Hills sheep population will be most
affected by the project because of the 1 ocat ion of a
major mineral lick on Jay Creek. The area used by
sheep is a steep bluff extending from the creek
bottom at 200 feet ( 610 m) to the rim at 2450 feet
( 74 7 m). A ridge on the east side of the creek
2252 feet {692 m) elevation) is also used. Approxi-
mately 42 percent of the 1 i ck surface area wi 11 be
inundated each year when the Watana impoundment is at
its maximum 1 evel 2190 feet ( 668 m) ( 668 m). How-
ever, during the months of maximum lick use {May and
June), the reservoir level will be approximately
2093 feet {636 m) (May 1) and 2100 feet {638 m) (June
1), and thus only about 22 percent of the lick will
be under water. Sheep appear to use the 1 ower ha 1 f
of the lick more frequently than the upper half
(ADF&G 1982d, no quantitative data provided) and,
therefore, these percentages may underestimate the
amount of soil that will be inundated. Most licks
are created and/or maintained by water action along
creeks or lakes, and it is unlikely that sheep will
discontinue use of the lick because of partial
E-3-419
4.3 -Impacts -Watana
inundation. Erosion caused by the reservoir may
enhance the lick by exposing new soil, but may also
1 each important ions from the soil. Of greater
immediate consequence than the decrease in surface
area of the 1 ick is the disturbance of sheep using
the lick. Frequent visits to the lick (mostly with
helicopters) by researchers, other project personnel ,
and visitors touring the project area have undoubt-
edly affected the sheep using the lick. The lick is
far removed from adequate escape habitat, and these
frequent helicopter trips into Jay Creek for purposes
of viewing the lick could result in its abandonment
if continued. Recreat i oni sts accessing the area by
boat after the impoundment has filled could have a
similar effect.
The consequences to the Watana Hills sheep population
if the Jay Creek lick is abandoned for any reason are
unclear. Several other mineral licks have been iden-
tified within the range of this population, but
because sheep have a demonstrated high fidelity to
specific licks, it is uncertain whether these alter-
native licks would replace Jay Creek. Many research-
ers have conducted chemical analyses of mineral lick
soils in an attempt to explain why sheep visit licks,
but the results have been conflicting or incon-
clusive. Contamination of samples from urine, feces,
and/or muddy water have been cited as potential
sources of error in these analyses. Many studies
have found that sodium is relatively abundant in lick
soils and is selectively sought by ungulates (see
Stocks tad et al. 1953 and Tankersley 1981). Plants
other than halophytic species absorb only a small
percentage of the sodium present in the soil, and it
is therefore possible that forage species are unable
to supply the quantity of sodium needed by big game
(Stockstad et al. 1953). Heimer (1973) found that
soil samples from high use sites within a mineral
lick contained large quantities of clay minerals
called zeolites which contain biologically available
cations of sodium, potassium, calcium, and
magnesium.
(d) Brown Bear
Anticipated and hypothesized impacts to brown bears are
summarized in Table E.3.149. Probable factors regulating
brown bear populations in the Susitna Basin and actions that
might affect populations are illustrated in Figure E.3.110.
E-3-420
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4. 3 -Impacts -Watana
Brown bear-human conflicts are a major concern of develop-
ment project planners in the north and are treated in this
section. Other impacts include spring habitat loss, dis-
turbance, and impediments to movement. Indirect impacts
associated with increased access are likely. to be serious.
(i) Construction
The two major impacts of the project on brown bears
during the construction phase will be the loss of
spring feeding areas during and after clearing, and
direct mortality of bears resulting from bear/human
conflicts at camps, construction sites, and bear con-
centration areas. Unregulated hunting by construc-
tion workers would also have a major impact on brown
bears during this period.
Several food sources have been identified that appear
to be season a 11 y important to brown bears in the
Susitna Basin. These include spawning salmon in July
and August at Prairie Creek, early spring herbaceous
growth and overwintering· berries along the lower
slopes near the river bottom, widely scattered berry
patches on the benches above the river, carrion and
moose calves near the river and its tributaries, and
vegetation along tributaries such as Deadman Creek.
Some bears may avoid areas of intensive human activi-
ty, thus affecting their movements between these
widely scattered food sources. However, because
brown bears range widely and frequent open habitats,
it is unlikely that the intensive human activities
near the damsite and borrow sites, or the presence of
a cleared impoundment area in the last year or two of
the construction phase, would prevent bears from
reaching food sources outside the intensively used
construction area.
The greatest impact on food sources during the first
few years of the construction period will occur near
the damsite, where facilities and human activities
will be concentrated. A much greater reduction in
spring food availability will occur during and after
impoundment clearing. The availability of early
spring foods to brown bears will be reduced both as a
result of direct habitat removal near the construc-
tion sites, and by alterations of bear movements
along the river. Because the food requirements of
brown bears are so poorly understood, it is not
possible to equate losses in food supplies to losses
E-3-421
4.3 -Impacts -Watana
in number of bears. It is thought that the riparian
areas are most important to bears in early spring,
just after they emerge from dens. SnoWT~el t occurs
sooner in these areas (particularly on south-facing
slopes), making overwintering berries and green
growth available to bears when they have low energy
reserves. Moose calving is also concentrated in
riparian areas, and brown bears have been shown to be
effective predators of both adult and young moose
(Ballard et al. 1980).
The loss of early spring feeding areas near the con-
struction site wi 11 probably not affect the popul a-
tion size or productivity of brown bears during the
short construction period. Reservoir clearing acti-
vities will cause a reduction in carry·ing capacity,
but it is doubtful that this alone would cause
measurable population effects in the one or two years
of the construction phase when clearing occurs.
Brown bears eat sparingly for several weeks after
emerging from dens during a transition stage from
hibernation to normal activity (Craighead and
Mitchell 1982). As food becomes increasingly
available, the bears• food consumption increases.
Craighead and Mitchell {1982) reported that bears in
Yellowstone Park during April and May continued to
utilize body fat stored the previous fall, and that
weight gains were not noticeable until late July and
August. Berry production appears to be highest on
the benches above the river (above the impoundment
level) where snowmelt occurs 1-3 weeks later than on
the south-facing slopes bel ow 2200 feet. If bears
are able to subsist on fat reserves for these few
weeks, a more abundant food supply w"il 1 become avail-
able.
Craighead and Mitchell (1982) also reported that
although brown bears feeding primarily on green vege-
tation in spring failed to gain weight, those secur-
ing high-protein food such as carcasses, the young of
big game species; or garbage maintained or increased
their weight. This suggests that a decrease in ungu-
late populations may have as great an affect on bear
condition in the spring as would a decrease in the
availability of green vegetation. If project person-
nel are not allowed to hunt, the effects of the pro-
ject on moose during the construction phase are
expected to be mostly distributional (as opposed to
changes in population size), and no changes in
E-3-422
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4.3 -Impacts -Watana
caribou numbers are expected. Thus, it is unlikely
that noticeable changes in the number of brown bears
as a result of altered spring food availability will
occur during the construction period. During the
filling and operation phases, however, the 1 oss of
spring feeding areas will have a major impact on
brown bears.
Brown bears have one of the lowest reproductive rates
of any land mammal in North Jlrnerica (Bunnell and Tait
1978). This, coupled with the low densities of brown
bears in most parts of their range, makes the impact
of sustained high levels of mortality particularly
severe (Craighead et al. 1974). Typically, causes of
direct bear mortalities during construction of pro-
jects in their range include killings in 11 defense of
life and property", control kills of nuisance animals
by appointed agency or project personnel (Cole 1971);
accidental deaths of bears during attempts to fright-
en or t~ap and transplant animals; and increased.
hunting and poaching pressure resulting from improved
access and higher numbers of people (Rogers et al.
1976, Nagy and Russell 1978, JFWAT files). Acciden-
tal deaths of bears from blasting or destruction of
dens also occur but are less common (JFWAT files).
Human activities related to the Trans-Alaska pipeline
project (TAPS) resulted in a minimum of 11 brown bear
and 30 black bear deaths (JFWAT files). One of the
most serious prob 1 ems encountered during TAPS con-
struction resulted from the attraction of bears to
areas of human activity. Bears quickly discover and
utilize jmproperly handled food and garbage at camps,
worksites, or dumps (Barnes and Bray 1967, Craighead
and Craighead 1972a, Meagher and Phillips 1980). The
effects of bears• concentrating at artificial food
sources such as dumps are not clearly understood, but
there is some evidence that higher cub mortality from
predation by adults and higher disease and parasite
loads may result when bears are concentrated (Cole
1971). Brown bears from hunted populations such as
that in the Susitna Basin are less likely to be
attracted to camps and dumps than are those in
unhunted populations, but some brown bears can still
be expected to frequent these areas.
Human activity in bear habitat poses problems for
people and thus for bears. Fatal attacks by bears
occasionally occur when artificial food sources
E-3-423
4.3 -Impacts -Watana
attract habituated bears to sites of human activity
(Craighead and Craighead 1972a, Hamer 1974, Herrero
1976). Females with cubs, very old bears, and habit-
uated bears pose the most serious threats {McArthur
1969}. Besides serious maulings, minor injuries such
as bites and scratches frequently result from at-
tempts to feed bears (Eager and Pelton 1980).
Extremely serious bear /human conflicts occurred
during the TAPS project {JFWAT files).
There are several specific areas and seasons where
human/bear conflicts might occur. Areas where bears
congregate to feed on salmon in late summer are like-
ly to be attractive to project personnel as fishing
sites. Brown bears tend to concentrate near the
river to feed on vegetation during early spring, soon
after emerging from dens; thus, bear/human encounters
near the construction site and borrow sites may be
frequent at that time. The proposed camp is likely
to be frequented by bears if proper food storage and
disposal methods are not implemented. Also, the camp
is located in prime berry habitat used by bears in
late summer and early fall. The ongoing bear studies
will provide the information needed to further iden-
tify such bear concentration areas.
Bears are reported as one of the large mammals more
sensitive to aircraft disturbance (Klein 1974,
McCourt et al. 1974). The reactions of bears to air-
craft have been recorded in several studies (Quimby
1974, Ruttan 1974, Harding 1976); there is much
individual variation in their reactions, probably
related in part to previous experience (Linderman
1974, Pearson 1975, Harding and Nagy 1977}. Bears
seem to react more strongly to helicopters than to
fixed-wing aircraft (Quimby 1974, Harding and Nagy
1977}. Low-flying aircraft near feeding sites could
affect the productivity of brown bears if disturbance
is frequent enough.
The impacts of the project on brown bears downstream
from the Watana dam will be 1 imited mostly to air-
craft disturbance and increased hunting, since down-
stream flows will not be-altered until the filling
phase. No measurable changes in the number of moose
or other important prey species are expected,
although there may be some noticeable shifts in th.e
distribution of prey species away from the construc-
tion sites. Fish and mammal populations downstream
E-3-424
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4.3 -Impacts -Watana
( i i)
from the Devil Canyon site would be affected primari-
ly by increased fishing and hunting pressure, and no
impact on brown bears should result given the current
hunting and fishing regulations.
Filling and Operation
The loss of habitat as a result of the impoundment
clearing and filling and the partial avoidance of
project facilities will have the greatest impact on
brown bears during the filling and operation phases.
Indirect effects of decreased moose populations and
increased hunting by people will also have measurable
effects on brown bears. There is also some potential
for the impoundment to interfere with bear movements,
particularly during the spring.
The impoundment will affect the brown bear population
primari 1 y through decreased avai 1 ability of moose,
berries and green vegetation. Although the loss of
early spring feeding areas near the dam site during
the construction period is not likely to measurably
affect the population, the loss resulting from
impoundment of the river will decrease carrying capa-
city. Brown bears must bui 1 d up 1 arge fat reserves
during the six-month period that they are out of dens
to sustain them through the winter and early spring.
Following the 1981 berry crop failure, Miller (1982
Personal communication) reported that two of the four
females expected to have cubs in 1982 did not,
suggesting that the poor nutritional condition of
females in the fall may have caused a 1 ower produc-
tivity the following year. Pelton (1982) reported
for black bears that years of poor berry or acorn
production can result in delayed first estrus,
decreased litter sizes, and increased incidence of
barren females. In addition, overwintering berries
appear to be a particularly important spring food for
some bears. Yearlings, which emerge from dens in
poor condition and suffer higher rates of mortality
than other age classes, may be particularly sensitive
to loss of overwintering berries as a spring food
source. The permanent loss of habitat and early
spring foods in the impoundment area wi 11 therefore
cause a decrease in the carrying capacity of the
project area for brown bears. The decrease in the
number of moose availabl~ to bears, in combination
with the loss of berries and other vegetation and any
alteration of plant phenology in the impoundment
E-3-425
4.3 -Impacts -Watana
zone, will cause an even greater reduction in the
carrying capacity of the area.
The impoundment is not expected to be an absolute
barrier to brown bear movements, except possibly dur-
ing the spring. Some interference with movements
between food sources will occur, but the number of
bears affected and the consequnces in terms of pro-
ductivity or survival cannot be predicted. Brown
bears usually emerge from dens in Apri 1, and most
have entered new dens by the end of October. Thus,
the reservoir wi 11 be ice-free during most of the
time bears are out of their dens. Brown bears com-
monly swim long distances in the ocean to offshore
islands (Miller and Ballard 1982, Roseneau 1982
Personal communication), and the open water in the
reservoir should not physically obstruct crossings.
The ice on the reservoir is expected to begin melting
in early March, and the reservoir should be ice-free
by late May to early June (Bredthauer and Drage
1982). During April and May, bears attempting to
cross the reservoir will be confronted with ice
shelves and blocks, wide mudflats, and thin and
broken ice conditions. There will also be open-water
conditions near the intake structures and downstream
from the dam. It is not known whether one or more of
these factors might deter bear crossings, but these
spring conditions would be more likely to affect
movements than would the open water 1 ater in the
summer.
Indirect impacts on brown bears downstream from
Watana wi 11 result from reduced populations of moose
and salmon and from increased hunting along the
transmission corridor. Moose and salmon studies are
being conducted along the 1 ower river in an attempt
to quantify project impacts. The carrying capacity
of the areas adjacent to the river will decrease if
salmon and moose populations are substantially
reduced.
Hunting pressure on brown bears wi 11 probably
increase in the upper Susitna basin because of the
improved access afforded by the reservoir and access
road. Also, many of the workers who helped to con-
struct the dam may return to the area to hunt. This
increased hunting pressure will likely result in
lower bear densities and a younger age structure in
the brown bear population (ADF&G 1982e).
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4.3 -Impacts -Watana
(e) Black Bears
Anticipated and hypothesized impacts to black bears are
summarized in Table E.3.150. A large proportion of the
acceptable black bear habitat in the middle basin will be
eliminated. Disturbance will also be a serious impact, as
will black bear/human conflicts.
( i) Construction
The 1 ong-term impact of the Watana development on
black bears will be much greater than that for brown
bears, si nee the impoundment and other project faci-
lities will remove a large proportion of acceptable
black bear habitat in the Watana area. However,
habitat 1 oss may not be the most serious impact on
black bears during the first few years of the con-
struction period, when attraction to artificial food
sources, disturbance of bears at denning and feeding
sites, and increased levels of hunting are more like-
ly to have serious effects (see Figure E.3.111).
Black bears in the vicinity of the proposed Watana
impoundment are restricted to a band of conifer
forest adjacent to the river. Between Watana Creek
and the Tyone Rivers, this band of forest becomes
increasingly constricted. The construction site,
borrow sites, camp, airport, and other facilities
will remove a large proportion of the black bear
habitat, thus concentrating the bears into the limit-
ed remaining areas. Black bears are more likely to
frequent the camp and construction sites than are
brown bears, and this will cause problems for both
people and bears {see 4.3.1[d]). Deliberate feeding
of bears by project personnel at construction sites
will intensify the problem.
Borrow sites D and F are located in the tablelands
and are used by black bears foraging for berries in
late summer {ADF&G 1982e). Bears will be affected
both by the direct removal of this rich food source
and by a greater 1 i kel ihood of contact with humans,
which could lead to some bear mortalities. The other
borrow sites are in forested areas used by black
bears throughout the year, and the mining of con-
struction materials from these sites will cause a
reduction in the availability of denning sites and
feeding areas.
E-3-427
4.3 -Impacts -Watana
Black bears in the Susitna Basin typically den at
elevations bel ow 3,000 feet, and 9 of the 13 known
black bear den sites in the Watana impoundment area
will eventually be flooded. Assuming that other dens
occur above or below the impoundment level in the
same ratio, 69 percent of the black bear denning
habitat in the Watana impoundment vicinity will be
lost. Since dens are concentrated near the river
where human activity will be greatest, there is also
the potential for disturbance to cause den
abandonment or to make some denning areas
unacceptable. Many of the dens sites were reused by
the same or a different bear, which may indicate a
scarcity of acceptable sites. Human activity on the
ground and 1 ow-flying aircraft can both cause den
abandonment. As discussed for brown bear, den
abandonment in winter when the ground is frozen may
result in a bear's death.
Because black bears will be concentrated near the
river and may have increased movements while search-
ing for food, any increase in hunting pressure during
the construction period could have a substantial
effect on the population. If black bears do increase
their movements away from forested areas, as they do
during berry crop failures (ADF&G 1982e), there is
also a potential for increased mortality caused by
encounters with brown bears.
(ii) Filling and Operation
Black bears will be affected in several ways during
the clearing of the impoundment area and initial fil-
ling period. The loss of feeding areas, disturbance
at den sites, and increased contacts with people will
all result in severe habitat degradation within and
adjacent to the impoundment area. Bears occurring in
the impoundment area will likely increase their move-
ments away from the river, thus increasing contacts
with brown bears and hunters. There is little like-
lihood of bears being drowned while in their dens
during reservoir filling, since winter flows into the
reservoir wi 11 be very 1 ow, and most of this flow
will be released downstream.
After filling, it is unlikely that a viable resident
black bear population will exist upstream from Watana
Creek. Transient bears may use areas adjacent to the
E-3-428
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4.3 -Impacts -Watana
(f) Wolf
impoundment~ and a few bears may reside there year-
round. However, the lack of denning areas and ade-
quate forest stands near the remaining food supplies
will severely limit the resident population. These
bears will also be quite susceptible to hunting along
the reservoir margin. Many bears residing downstream
from Tsusena Creek made movements in 1980-82 upstream
to feed on berries, and the road and other permanent
facilities may interfere with these movements. Other
1 ong-term impacts are 1 i kely to be similar to those
for brown bears (see 4.3.1(d)). Black bears, like
brown bears, are able to swim long distances, and the
open water in the impoundment should not be an abso-
1 ute barrier to their movements. Some effects on
bear movements, however, can be expected. Since
black bears. in the Watana watershed wi 11 be subject
to serious habitat loss, the cumulative impacts to
vegettion and prey populations are likely to be of
greater importance than for brown bear.
Downstream effects of the Watana development on black
bears are 1 i kely to be much 1 ess severe. Impacts on
salmon spawning areas, aircraft disturbance, and
increased hunting wi 11 probably have the greatest
effect on the population. The expected successional
changes in vegetation are not likely to have a
noticeable effect on the population, nor will any
open water areas during winter, since bears will be
in dens at that time. The importance of salmon to
downstream bears is unknown, but several bears from
the middle basin moved downstream to feed on salmon
during a berry crop fai 1 ure, and bears are commonly
seen along spawning sloughs. in late summer (ADF&G
1982e). Twenty percent of the salmon radio-tagged
during studies downstream were eaten by ·bears
(Miller 1982 Personal communication). However, bear
scats found along salmon streams comprise mostly
berries. and thus the importance of salmon to these
bears is uncertain. Bear studies downstream from
Devil Canyon will be intensified in 1983, and conse-
quently, the food habits of downstream bears wi 11 be
better defined at that time.
Anticipated and hypothesi zed impacts to wo 1 ves are summa-
rized in Table E.3.151. Wolves may be affected by construc-
tion and operation of the Watana development by some loss of
den and rendezvous sites, by disturbance, by increased
E-3-429
4.3 -Impacts -Watana
hunting (see Section 4.3.5}, and indirectly, by loss of food
sources. The Watana pack in particular may be seriously
affected by the loss of habitat for the major prey species -
moose, within their territory.
No known dens or rendezvous sites wi 11 be flooded or de-
stroyed by the present construction zone plans. Some den
and rendezvous sites that have not been located may be
destroyed, but because potential sites are relatively
abundant in the Susitna Basin (ADF&G 1982f). this would not
have a serious effect on wolf populations.
Under most circumstances, wolves readily habituate to man-
made disturbance (Van Ballenberghe et al. 1975, Milke 1977).
The major exceptions to this are disturbances at den sites
in spring. During Susitna baseline studies (ADF&G 1982f},
human disturbance at three den sites caused early abandon-
ment of all three, the adults moving the pups to new 1 oca-
tions. In these cases. the pups were probably a month old
and no pup mortality was noted. ADF&G (1982f) speculated
that younger pups might be more likely to die if moved from
the whelping den prematurely. Abandonment of dens after
disturbance has also been noted in other areas of Alaska and
in Canada (Carbyn 1974. Chapman 1977). Aside from disturb-
ance at dens, disturbance alone is unlikely to cause notice-
able changes 1n the distribution of wolves or home range use
of individual packs.
A serious impact of increased interactions between humans
and cani ds (wolves and foxes) is the threat of exposure to
rabies. That wolves (and bears and foxes) do habituate to
the presence of humans was demonstrated by problems encoun-
tered during the construct ion of the Trans-Alaska P·i pel i ne
(Milke 1977}. Wolves were fed deliberately and were allowed
to scavenge on unburned garbage at construction sites and
camps. As a result, many animals became severe nuisances
and were killed. In addition, instances of workers being
bitten and requiring hospitalization and occasionally rabies
vaccine occurred.
Loss of food sources through development impacts on prey
species will be another impact of the Watana development on
wolves. Wolves in the middle Susitna Basin prey primarily
on moose and to a lesser extent on caribou. Caribou popula-
tion levels are not likely to be seriously affected by the
Watana development, but moose populations will be reduced.
The extent to which this reduction actually affects wolves
depends on the extent to which wolf populations are limited
by food availability rather than by human exploitation, and
E-3-430
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4.3 -Impacts -Watana
on the distribution of the reduction in prey availability
relative to territories of individual packs.
Van Ballenberghe et al. (1975) reviewed the available liter-
ature on factors controlling wolf populations. They
believed that while social factors such as territoriality
and stress were the ultimate factors controlling population
1 evel s, an abundant food source 1 owe red the threshold for
action of social factors. They suggest that food is the
main factor permitting the development of dense wolf popu-
lations (Figure E.3.112).
There are few data to indicate wolf population trends in
relation to population trends of moose and caribou in the
Susitna Basin. However, the consistently high harvest of
wolves through the 1970s (Section 4. 2.1[f]) suggests that
the low caribou population and declining moose population in
the early 1970s (Section 4.2.1 (a) and (b)) did not cause a
substantial reduction in wolf numbers.
Wolf population levels are currently controlled by exploita-
tion rates. Close to half the middle basin wolf population
is removed each year by legal and illegal hunting (Section
4.2.1 [f]). In the l-Ikely event that this situation con-
tinues, the reduction in the moose population as a result of
the project should have 1 ittl e effect on the regi anal wolf
population. Only if the harvest level is greatly reduced
through better enforcement and/or altered management prac-
tices, will the density of moose and caribou become the
major factor controlling the wolf population.
On the other hand, the Watana pack will be seriously affect-
ed by inundation. As a result of habitat loss, reductions
in the moose population, and disturbance near den and
rendezvous sites, it can be assumed that this pack of up to
14 wolves will be eliminated. If prey densities become the
major factor cantrall ing wolf populations, reduced moose
numbers and altered caribou movements would affect the
potential carrying capacity of the area and cause measurable
changes in the productivity and territory size of as many as
10 other packs. Several wolf packs will also experience
positive impacts because of improved hunting conditions
along the impoundment shoreline, lower brown bear numbers,
and altered distributions of moose and caribou.
Displacement of prey animals from the reservoir area may
result in a temporary increase in wolf density in adjacent
areas. However, the 1 ass of habitat from the impoundment
may cause adjustment of territory boundaries with
E-3-431
4.3 -Impacts -Watana
neighboring. packs, and a decrease in both wolf and moose
density from temporarily higher levels would ensue.
(g) Wolverine
Anticipated and hypothesized impacts to wolverine are summa-
rized in Table E.3.152. The Susitna Hydroelectric Project
will have both positive and negative effects on the wolver-
ine population in the middle basin. Wolverines will be most
affected by changes in winter food availability and by high-
er trapping mortality resulting from improved access and a
larger human population in the area. Other factors such as
a 1 ocal i zed avoidance of camps and roads, disturbance from
aircraft and construction activities, and habitat loss
caused by the impoundments and other project facilities are
not likely to greatly affect the number or productivity of
wolverines in the Susitna Basin. Loss of den sites is not
likely to be a problem since wolverines den in a variety of
habitats, generally on the surface of the ground under snow.
Downstream from Devi 1 Canyon, wo 1 veri nes are 1 i kely to be
measurably affected only by any increase in trapping pres-
sure resulting from the project. Each of these factors will
be discussed in greater detail in the following sections.
The area in northwestern Montana studied by Hornocker and
Hash ( 1981) contained a 1 arge reservoir 32.2 mi 1 es ( 48 km)
long and up to 4.4 miles (6.5 km) wide, and thus some data
are available on wolverine movements and ranges in relation
to a large impoundment. They reported that 11 the size and
shape of ranges were not affected by rivers, reservoirs,
highways or major mountain ranges." Magoun (1982) stated
that, although topographic features were not physical bar-
riers to wolverine movements, they did appear to influence
the shape of home ranges to some extent. Rivers, ridges,
drainage divides, and well-defined breaks in habitat types
often coincided with home range boundaries in her study
area. Male home ranges appeared to be less affected by
topographical features than did female ranges. Some home
range boundaries in the middle Susitna Basin coincide with
topographical features {see Figure E.3.98), but no clear
relationship between the major features and most home range
boundaries is evident. It is possible that the Watana
impoundment might serve to' separate home ranges once it is
in operation.
Based on the estimate of about one wolverine per 40,320
acres {163 km2) derived in Section 4.2.l{g), the direct
loss of over 50,900 acres (206 km2) caused by the impound-
ments, access roads, camps, and other project features would
E-3-432
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4.3 -Impacts -Watana
(h)
lower the carrying capacity by about two wolverines. How-
ever, winter food supplies are usually greater at the lower
elevations most affected by the project facilities. Changes
in the ava i 1 abi 1 ity of winter food may affect wo 1 veri ne
movements, densities, and productivity; and therefore, it is
important to consider these changes in some detail.
The Watana impoundment will cause a decrease in winter food
availability. Because a relatively high proportion of the
forested area will be inundated, there will be a substantial
decrease in the availability of small mammals and grouse
used by a few wolverines during winter. The size of the
moose population in the vicinity of the Watana impoundment
will decrease during the license period, but there may be an
increase in the number of ungulate carcasses available to
wolverine. Some mortality of both moose and caribou is
expected from floating debris, thin ice conditions, and
large mud flats in the drawdown zone; and predation by
wolves and brown bears may increase along the shores of the
impoundment. Higher winter mortality of moose near the
impoundment is also expected during winters of moderate to
deep snow. It is not clear whether the more rapid turnover
of the moose population in the middle basin will offset the
lower density of moose and small mammals. The effects of
improved access from the roads and impoundment on wolverine,
including increased trapping mortality and human presence,
is discussed in Section 4.3.3(g).
Belukha Whale
The majority of the Cook Inlet population of belukha whales
appears to concentrate near the mouth of the Susitna River
during the calving period. Studies were undertaken in 1982
to address the concern that project-related changes in water
temperatures or anadromous fish runs at this critical period
might interfere with calving success. For example, Seargent
(1973, cited in ADF&G, unpublished report on 1982 Phase 1
Report) attributed the elimination of calving by belukhas in
the St. Lawrence River to hydroelectric development on the
Manicougan and Outardes rivers and subsequent alterations in
water temperatures.
Although water temperatures released from the dams wi 11 be
0-7°F (0-4°C} warmer than natural temperatures, the dilution
effect of other rivers and temperature exchange of the river
with the air and ground wi Tl result in no post-project
difference in water temperatures at the mouth of the river
during May and June. Only 7,650 cfs of the 55,930 cfs post-
project inflow into Cook Inlet in May will be from the
E-3-433
4.3 -Impacts -Watana
Susitna River (both dams operating). In June, only 8,150 of
105,702 cfs will be contributed by the Susitna. Thus, the
dilution factor of other water sources and 151 river miles
of temperature exchange with the environment will result in
similar pre-and post-project water temperatures at the
mouth of the river during calving.
Belukhas are thought to feed on the large runs of anadromous
eul achon (a major run occurred between June 1-9, 1982) and
on adult and out-migrating salmon. Eulachon are thought to
spawn in the lower mainstem and in the lower tributaries of
the river (McPhail and Lindsey 1970:198}, and the project
should have no effect on the number of eul achons avai 1 ab 1 e
to belukhas. However, eulachon investigations are currently
being conducted in the Susitna River to verify this predic-
tion. If all salmon spawning habitat in the sloughs up-
stream from Talkeetna were lost, about 5-8 percent of the
salmon available to belukhas would be unavailable. Given
this small potential decrease in food supply, the necessity
of applying a correction factor of 2 or 3 times the number
of belukhas counted during surveys (because of silty waters
and submerged whales), and the fact that it cannot even be
determined whether calves are present during surveys, it is
extremely unlikely that any measurable decrease in the
belukha population would occur as a result of the project.
(i) Beaver
The beaver population along the Susitna River is likely to
increase during the license period as a result of the Watana
development. Beneficial effects will occur mostly down-
stream from the dam as a result of regulated flows. Antici-
pated impacts to beaver are summarized in Table E.3.153.
(i) Construction
No active beaver lodges have been located during
surveys of the impoundment area, borrow sites, camp
sites, airport location, or damsite (Gipson et al.
1982), and, therefore, beaver should not be affected
by construction and clearing activities at these
sites.
(ii) Filling and Operation
No beavers are known to reside in the impoundment
area, and therefore, the flooding of this area will
not affect this furbearer species. The reservoir
will be of 1 ittl e value to beavers after fi 11 i ng
E-3-434
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4.3 -Impacts -Watana
because of the annual drawdown. A few beavers, how-
ever, may persist in using the reservoir area. Each
year for the past 12 years, beavers have attempted to
build 1 odges and food caches on Williston Lake in
British Columbia, which has an annual drawdown of
about 50 ft (15 m) (Bonar 1982 Personal communica-
tion). One innovative colony there has built its
lodge on a raft of floating logs, which moves up and
down with the water level; whereas another colony has
a series of burrows extending down to the minimum
d rawdown 1 eve 1 •
During filling, the river is to be passed directly
through the dam during the winter months, and thus,
the only effect of tt"\e dam on downstream flows wi 11
be during summer. During the operation phase, -down-
stream flows will be higher than present in the
winter, but lower in summer.
No beavers currently occur in the river reach between
Watana and Devil Canyon, and the estimated 70 beavers
between Devil Canyon and Talkeetna were found mostly
in side channels, sloughs, and clearwater areas
(Section 4.2.2[a]). Although swift currents in the
main channel probably contribute to these low densi-
ties, the greatly fluctuating water levels, ice
scouring events, and 1 ow abundance of early succes-
sional vegetation are probably the major limiting
factors (Figure E.3.113). Another limiting factor is
the depth of water beneath the ice in winter.
Beavers require at least 1.5 ft (0.5 m) of open water
under the ice for access to food caches and lodge
entrances (Scott 1940, Hakala 1952). Since winter
water depths are now much less than those in summer,
the winter flows determine which areas are suitable
for year-round occupation by beavers.
Any site currently occupied by beavers should still
be available post-project, since winter flows will be
higher than at present. In addition, many areas now
subject to freeze-out will also be available for
colonization by beaver. The increased availability
of early-successional vegetation, reduced ice-scour-
i ng, 1 ack of an ice cover in the Watana-Devil Canyon
reach, more stable year-round flows, and lack of
floods which destroy food caches and . other beaver
structures wi 11 a 11 result in improved downstream
habitat for beaver. Beaver habitat south of
Talkeetna may a 1 so be enhanced as a result of the
E-3-435
4.3 -Impacts -Watana
increased occurrence of favored food plants, but the
more unstable water levels resulting from increased
contributions from other rivers and tributaries will
dampen this effect.
(j) Muskrat
If construction camp personnel and their families are
allowed to trap in the area, beaver populations will
be affected both along the Susitna River itself and
in the lakes and creeks on either side of the river.
Anticipated impacts on muskrat are summarized in Table
E.3.153. Muskrats will be affected primarily as a result of
improved access for trappers. Some habitat 1 oss within the
borrow sites and impoundment zone will also occur; however,
muskrats may benefit from additional beaver ponds downstream
from the project (Section 4.3.1[1]). With the exception of
trapping mortality, the net impact on the muskrat population
should be negligible.
Of the 103 1 akes surveyed for muskrat sign in spring 1980,
17 occurred within borrow sites D or E or the impoundment
zone (Table E.3.154); only 5 of these lakes had muskrat
pushups (Gipson et al. 1982). A total of 13 pushups were
observed on these 5 1 akes, but the number of musk rats this
represents is unknown (pushups are temporary structures, and
one muskrat can create many of these during a winter). A
1 ikely estimate ot the number of muskrat to be lost as a
result of this habitat 1 oss is 5 to 10 anima 1 s. Improved
downstream habitat will compensate for this loss.
Muskrats are extremely susceptible to water level fluctua-
tions (Bellrose and Brown 1941), and usually find braided
rivers poor habitat because of 1 ack of forage and burrow
sites (Brooks and Dodge i981). As such, there is 1 ittle
potential muskrat habitat in the active floodplain down-
stream from the Watana damsite. Many muskrat probably
occupy beaver colony sites (Curatolo et al. 1981) along the
Susitna River that are outside the active floodplain. Below
Montana Creek good muskrat habitat occurs in old channels
now functioning as clear-water seeps which will not be
affected by the project (Bredthauer and Drage 1982).
If construction camp personnel and their families are
allowed to trap in the area, muskrat populations throughout
the lakes lying on either side of the Susitna River could be
seriously affected. Gipson et al. (1982) found muskrat sign
in these lakes and noted their vulnerability to trapping.
E-3-436
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4.3 -Im~acts -Watana
(k) Mink and Otter
(i} Upstream Effects
Anticipated and hypothesized impacts to mink and
otter are summarized in Table E.3.155. Because mink
and otter are moderately abundant in the middle
Susitna Basin (see Section 4.2.2 [c,d]) and are
dependent on aquatic and semi-aquatic habitats along
the Susitna River and its tributaries, construction
and operation of the Watana dam may have substantial
impacts on these species. The most important effects
include loss of habitat, reduction of food supplies,
increased disturbance, and barriers to movement.
Clearing and flooding of the impoundment will elimi-
nate a substantial proportion of good quality otter
and mink habitat. High quality habitat for these
semi-aquatic furbearers is generally characterized by
moderate-to-sl ow-flowing streams and rivers with
well-wooded banks. Ponds with abundant food, deep
and stable water conditions, and an irregular shore-
1 i ne also appear to be good habitats (Hodgdon and
Hunt 1953, Knudsen 1962, Barber et al. 1975).
Because the impoundment will result in a 1 arge draw-
down zone, it is unl"ikely that the reservoir will be
heavily utilized by mink or otter. Small declines in
water levels (e.g., less than 3.3 feet [1 m]} may
actually benefit mink during the winter by creating
air spaces under the ice that would allow them to
hunt more easily (Errington 1943, Harbo 1958}. How-
ever, the large drawdown area of the Watana dam will
probably be detrimental to otter and mink; it will
isolate their bank dens from the reservoir during the
winter and will probably reduce prey availability.
The extent to which otter and mink habitat will be
reduced and the effects on local populations are
difficult to assess. The impoundment will flood
approximately '53 miles (85 km} of the mainstream
Susitna River. In addition, portions of a number of
tributaries will be inundated by the impoundment;
these include Deadman Creek (2.3 miles of stream will
be inundated at maximum fill [3.7 km]), Kosina Creek
(4.2 miles, 6.8 km), Jay Creek (3.2 miles, 5 km),.
Goose Creek {1.2 miles, 1.9 km), and the Oshetna
River (2.0 miles, 3.2 km). The lower reach of
Tsusena Creek wi 11 be disturbed by gravel removal.
E-3-437
4.3 -Impacts -Watana
It is not known what these losses represent in terms
of a proportionate reduction of available mink and
otter habitat.
Clearing and flooding of the impoundment area will
reduce prey availability for otter and mink. Clear-
ing of forest cover will reduce the availability of
some mink prey such as sma 11 mammals and waterfowl.
Effects of erosion and consequent siltation, as well
as effects of dust that are associated with clearing
may also reduce the availability of fish and crus-
taceans. Flooding of the reservoir will probably
result in further reductions in prey availability;
crustacean distributions and productivity will
probably be altered by the drawdown zone; and the
species composition, abundance, and distr·ibution of
fish will change. In addition, because the reservoir
will greatly expand the amount of aquatic habitat,
fish wi 11 be 1 ess concentrated than they are at
present and more di ffi cult for otters and mink to
capture. The net result of these changes, in addi-
tion to the change of shoreline habitats, will be an
avoidance of the reservoirs by mink and otter. The
effects on productivity associated with these dietary
changes are unknown.
Clearing of the reservoir site and construction
activities, particularly in close proximity to
streams and rivers, may disturb mink and otter and
may result in interference with daily activities or,
in extreme cases, an avoidance of the area. Densi-
ties of the European otter {Lutra lutra), a species
closely related to river otter, along the River Terre
in England appear to be inversely related to the
amount of human disturbance (recreational fisherman)
and the amount of clearing of woodland cover along
the river banks {l¥1acDonald et al. 1978). Because
recreational use of the upper reaches of streams
along the north side of the impoundment will probably
increase during construction and operation, and
because the upper reaches of these streams may repre-
sent a moderate proportion of the remaining high
quality habitat for semi-aquatic furbearers, disturb-
ance effects on mink and otter could be important.
(ii) Downstream Effects
Alteration of the river hydrology and vegetation
communities as a result of the Watana dam has already
E-3-438
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( 1 )
been discuss.ed (Section 3.3.1). Both of these fur-
bea~ers commonly concentrate in open water stretches
of rivers and streams in winter (Barber et al. 1975),
and therefore, the reach of permanently open water
downstream from the Watana dam may benefit sma 11
numbers of mink and otter. Major impacts on these
species are not expected downstream from the dam.
Coyote and Red Fox
Coyotes occur in the Watana development area, but they are
so uncommon that development activities are unlikely to have
a quantifiable effect on them.
Coyotes do not appear to avoid areas of human activity; how-
ever, no studies have specifically evaluated the effects of
human disturbance on this species. Ferris et al. (1978)
demonstrated a s i gni fi cant preference of coyotes (based on
winter track count surveys) for an area within 656 feet
(200m) of a section of an interstate highway in Maine
relative to an area 656-1312 feet (200-400 m) from the high-
way. Track surveys also indicated that coyotes occasionally
used the right-of-way as a hunting or travel route. Penner
(1976) similarly concluded that coyotes preferred large
cleared areas and avoided undisturbed habitats within an oil
sands development area in northwestern Alberta.
Coyotes are likely to exhibit a significant increase in
population level in the development area only if wolves are
e1 imi nated. Wolves wi 11 exclude coyotes from their ranges
through physical aggression when encountered. Only when
wolf numbers are extremely low and packs are eliminated will
resident wolves allow expansion of coyotes into their terri-
tories. If wolves are locally exterminated and excluded
from portions of their territories near the development,
coyotes may colonize localized areas in low numbers.
Anticipated impacts on red foxes are summarized in Table
E.3.156. The major impact on red foxes will probably result
from trapping by construction workers and killing of
nuisance animals at camps and construction sites. Habitat
loss from flooding of the impoundment will not have a great
impact on foxes, since most individuals apparently utilize
areas above the high water line of the impoundment (2140 ft,
666 m elevation) during winter seasons when food availabil-
ity is most 1 imited, and areas to the east of the impound-
ment on the Lake Louise flats. Fox dens typically occur at
elevations of 3280-3937 feet (1000 m to 1200 m) and no foxes
or fox sign were found along the Susitna River or the lower
E-3-439
4.3 -Impacts -Watana
reaches of its tributaries in late winter or spring during
baseline studies (Gipson et al. 1982). Foxes did occur
along the Susitna at other seasons. An abundance of arian
and small mammal prey would be available for foxes during
summer and fa 11 , and 1 oss of habitat a 1 ong the river would
probably have negltgible or minor effects.
Red fox similarly do not appear to avoid areas of frequent
human activity. Observations of red fox and the location of
den sites in relation to the main road in Denali National
Park showed that red foxes did not avoid areas of frequent
human use and that in some cases would habituate to human
disturbances (Tracy 1977). Red foxes in Gatineau Park,
Quebec, appeared to commonly use areas in the immediate
vicinity of human disturbance and showed little avoidance of
areas frequented by snowmobilers {Neumann and Merriam
1972).
Foxes away from den sites habituate to human activity so
readily that they can become a nuisance at construction and
campsites if they are fed or allowed to feed on garbage
(Mi 1 ke 1977). The presence of scavenging foxes frequently
leads to workers being bitten and occasionally needing
hospitalization for rabies vaccine (Milke 1977). It also
often leads to the destruction of the foxes.
Although the fox population in the Susitna Basin is small
{Section 4.2.2[f]), it is apparently a source of juveniles
that disperse to adjacent areas (Gipson et a 1. 1982). An
increased take of foxes from currently low levels is expec-
ted because of improved access and residency of construction
personnel and may eliminate this source of dispersing indi-
viduals.
(m) Other Furbearers
This group includes species that occur primarily in forested
habitats--marten, lynx, short-tailed weasel and least
weasel. Anticipated impacts are summarized in Table
E.3.157. Impacts on marten are discussed in greatest
detail. As mentioned previously {Section 4.2.2[c]), marten
have historically been and continue to be economically the
most important furbearer in the vicinity of the impoundment
zones. Lynx are very uncommon in the middle Susitna Basin.
Weasels are probably quite common, but there is little
specific information on their abundance and distribution in
the basin.
E-3-440
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4~3 -Impacts -Watana
All of these species wi 11 suffer primarily as a result of
the loss of forested habitats to the impoundment, borrow
sites, and other project facilities. Probable factors
regulating marten populations in the Susitna Basin and
actions that might affect populations are illustrated in
Figure E.3.114. Gipson et al. (1982) have estimated the
number of marten in the winter population directly impacted
by loss of habitat in the Watana and Devil Canyon develop-
ments through a model based on the following data and
assumptions:
-Adult male marten home ranges are mutually exclusive and
adjoin one another so that all marten habitat in the
impounded area is inhabited (trapping likely affects this
assumption);
-Marten habitat is defined as forest, and marten are
restricted to this habitat type;
-A 1:1 sex ratio exists in all age classes of the popula-
tion;
-65 percent of the population are juveniles (less than 1
year old) (R. Archibald 1982, Personal communication,
cited by Gipson et al. 1982), and juveniles appear in the
harvest in proportion to their number in the population;
and
-The mean home range size of male marten is 1685 acres
(682 ha) (Gipson et al. 1982).
This model gives an estimated density for all age/sex groups
of 0.0034 marten per acre {0.0085 per ha). Using a figure
of 11,798 ha of forest habitat 1 ost to impoundment areas,
borrow sites, construction sites, and camps, habitat sup-
porting 100 marten (3.4 percent of the Susitna watershed
upstream from Gold Creek) would be lost.
P. Gipson (1982 Personal communication) attempted an inde-
pendent population estimate in July 1982 near Watana Creek
using a mark-recapture technique. A 6.8-miles (11-km)
trapl i ne with trap spacing of 1312 feet ( 400 m) on either
side of Watana Creek captured no marten in 252 trap nights.
The minimum expected catch was ten, based on densities of
0.003 marten per acre (0.008/ha) and assuming all marten
within 1640 feet (500 m) of the trapline were captured.
This result suggests that fewer marten than calculated above
may actually exist in the impoundment areas, and that fewer
marten would be affected.
E-3-441
4.3 -Impacts -Watana
There are obvious difficulties with the model. Perhaps the
most serious is that marten densities and home ranges vary
among different forest types. being most common in dense,
mature coniferous forest (deVos 1952, Douglass et al. 1976,
Koehler and Hornocker 1977). If only closed forest habitat
were used in the calculations (eliminating woodland and open
forest types), habitat supporting 26 marten (7.5 percent)
waul d be e1 imi nated from that currently supporting 34 7
marten.
Clearing of forested areas at construction sites and borrow
areas and the associated human disturbances may affect mar-
ten home range size and distribution. However, these types
of changes will be most extensive in areas affected by the
access route and transmission 1ine and are discussed in Sec-
tions 4.3.3 and 4.3.4.
Lynx are uncommon in the Susitna Basin, probably because
their major prey, snowshoe hares, have been historically
uncommon. Habitat loss wi11 probably eliminate the few lynx
occurring .near the impoundment.
Numbers of short-tailed and
reduced through habitat loss.
affected, 1 ess than 5 percent
1 ost.
least weasels may also be
Based on the amount of area
of their population wi 11 be
Construction activities and human disturbance caul d result
in avoidance of the construction zone by furbearers. No
information is avai1able for lynx and weasels. Evidence
exists that marten are tolerant of moderate levels of
disturbance in areas adjacent to logging operations (Clark
and Cambell 1977, Soutiere 1978, Steventon and Major 1982).
(n) Raptors and Ravens
General types of potential impacts to raptors that occur
with development are summarized in Table E.3.158. The
construction and operation of the Watana dam will affect
raptors through a num~er of mechanisms (Table E.3.159), the
most important of which are habitat 1 oss and disturbance.
Habitat loss includes the flooding of suitable nesting
cliffs, removal of trees used for nesting and perching, and
a 1 oss of hunting areas. Many of the tree and cliff nests
within the impoundment area may be abandoned during the
construction phase as a result of disturbance, and several
nest sites immediately adjacent to the access road or borrow
sites may also be abandoned.
E-3-442
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( i) Habitat Loss
-Nesting Habitat
Nesting 1 ocat ions for most c 1 iff and tree-nesting
raptors are defined as a cliff or stand of trees
which may contain one or more nest sites. A pair of
raptors uses only one nesting location in a given
breeding season. However, a pair may have one or
more alternative nesting locations. Nest sites are
defined as the actual nests or ledges on cliffs, or
the actual nests in trees used by a pair of raptors.
A pair uses only one nest site in a given breeding
season, but may have one or more alternate nest sites
at a nesting location.
The distribution, quantity, and quality of nesting
locations and nest sites clearly limits the numbers
and nest success of most raptors, including both
cliff-nesting and tree-nesting species (Newton 1979).
Cliff-nesters are especially limited by availability
of nesting locations and nest sites in many regions
because suitable nesting ~liffs (i.e., those meeting
the specific nesting requirements of a species) are
fixed geologic features whose presence or absence are
a result of geologic events which are bound in geolo-
gic time. In contrast, tree-nesters rely on vegeta-
tive features for nesting locations and nest sites.
Succession and growth of vegetation is on-going and
occurs relatively rapidly in contrast to formation of
cliffs, and therefore, tree-nesting locations and
nest sites are both lost and replaced in much shorter
periods of time. However, for some tree-nesting
species (e.g., bald eagles) the times required for
replacement may represe'nt several generations of
birds, especially at northern latitudes. Because
raptors are one of the few groups of birds whose
distribution (within each species' breeding range),
numbers, and even nesting success are clearly limited
by the distribution, quantity, and quality of nesting
locations and nest sites, mitigation measures which
provide compensatory nesting locations and nest sites
can be particularly effective (see Appendix 3.1).
There is no reason to doubt that most raptors in the
Alaska Range are considerably more limited by nesting
1 ocat ions and nest sites than by other parameters
such as food. Loss of nesting locations and nest
E-3-443
4.3 -Impacts -Watana
sites will almost certainly be the single most
important adverse impact of Susitna development to
raptors in the Susitna River drainage. However, a
distinction can be made between the prominent cliff-
nesters (i.e., golden eagles, gyrfalcons) and the
prominent tree-nesters (i.e., bald eagles, goshawks)
that serves to help identify the relative degrees to
which the Susitna Hydroe1 ectri c project wi 11 impact
populations of these two groups of raptors within the
Susitna River drainage.
For golden eagles and gyrfalcons (cliff-nesters),
most of the suitable nesting locations available in
the Susitna drainage are clearly concentrated in the
middle basin along the river and along the lower
reaches of its tributaries between Vee Canyon and
Devil Canyon. Despite the quantity of this habitat,
gyrfalcons are apparently not especially locally
numerous. The paucity of gyrfalcons, but the pre-
sence of a relatively larger number of golden eagles
is likely a result in large part of geography--the
area is near the southern limit of the gyrfalcons'
breeding range in south-central Alaska, but well
within the breeding range of golden eagles. In
contrast to the quantity and quality of cliff-nesting
habitat concentrated along the Susitna River between
Vee and Devil canyons, the occurrence of suitable
nesting locations for golden eagles is much lower
throughout the remainder of the middle and upper
Susitna basins (Bente 1982 Personal communication,
Roseneau 1982 Personal communication). Furthermore,
the density of suitable nesting locations for golden
eagles is probably relatively low throughout much of
the remainder of the Alaska Range (Bente 1981), and
regi anal topography further suggests that con centra-
tions of cliff-nesting habitat similar to that found
along the Susitna River in its middle basin are at
best uncommon. As a consequence, direct losses of
cliff-nesting locations in the middle basin as a
result of canst ruction of the Susitna Hyd roel ectri c
project are judged to be reasonably si gni fi cant to
the golden eagle population inhabiting the Susitna
River drainage.
In the case of bald eagles and goshawks (tree-
nesters), the majority of appropriate nesting habitat
containing suitable nesting locations and nest sites
clearly 1 i es downstream of Devil Canyon. Upstream of
Devil Canyon in the middle basin appropriate nesting
E-3-444
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4.3 -Impacts -Watana
habitat for both species is sparse. Farther upstream
in the upper basin appropriate nesting habitat
becomes nearly non-existent. Pairs of both species
that nest throughout the Susitna River drainage
upstream of Devil Canyon are clearly members of much
larger downstream populations inhabiting the consid-
erably greater amounts of appropriate nesting habitat
found there. As a consequence, direct losses of bald
eagle and goshawk nesting 1 ocati ons in the middle
basin, as a result of construction of the Susitna
Hydroelectric project, are judged to be of reasonably
minor consequence to populations of those species.
Specific losses of known nesting locations of both
cliff-nesting and tree-nesting raptors and ravens are
discussed in greater detail below. The reader is.
reminded that numbers and percentages given below
represent known losses within the local vicinity of
the Susitna Hydroelectric project, and they should
not be interpreted to necessarily represent the
degree to which total Susitna River drainage popula-
tions or regional populations of these species are
affected by the project.
Eighteen of 41 (44 percent) of the known raptor and
raven cliff-nesting locations and 4 of 10 (40 per-
cent) of the known raptor tree-nesting locations in
the general vicinity of the proposed project will be
1 ost as a result of the Watana development (Tables
E.3.160 and E.3.161). These include known nesting
locations for the following raptors: golden eagles,
bald eagles, gyrfalcons, goshawks, and ravens.
At least 6 {38 percent) of the 16 total known golden
eagle nesting locations in the general vicinity of
the project area wi 11. be directly 1 ost to construc-
tion and filling of the Watana reservoir. Five of
those 6 nesting locations will be inundated, whereas
one may be lost during material excavation operations
at Borrow Site E (Figure E.3.115, Tables E.3.160,
E. 3.161, and E. 3.162).
Cliff-nesting habitat for golden eagles will become
severely limited upstream from the Watana damsite
once the impoundment is full. Loss of cliffs up-
stream from the Watana damsite may increase the im-
portance of cliffs farther downstream in Devil
Canyon~ a 1 ong Fog Creek, Tsusena Creek, and other
streams draining into the Watana to Devil Canyon
E-3-445
4.3 -Impacts -Watana
reach. Howevers airspace is restricted in much of
Devil Canyons many of the cliff areas appear to be
exposed to higher levels of moisture, and existing
cliffs may lack suitable ledges on which golden
eagles could construct nests.
Golden eagles often have several alternative nesting
locationss some perhaps 4-5 miles (6-8 krn) apart
(McGahn 1968s Roseneau et al. 1981)s and thus the 6
nests lost to the project do not represent 6 pairs of
eagles. The middle Susitna River basin population of
golden eagles wi 11 probably be reduced by 3-5 pairs
as a result of the construction and filling of the
Watana reservoir because of (1) losses of 38 percent
of the well-established golden eagle nesting loca-
tions along the river; (2) concomitant losses of most
of the other potential cliff nesting habitat upstream
from the Watana damsite; and (3) a suspected scarcity
of alternate nesting locations throughout much of the
remainder of the middle basin.
Four of 8 (50 percent) known bald eagle nesting loca-
tions in the general vicinity of the project area
will be lost to clearing and filling of the reservoir
(see Figure E.3.115s Tables E.3.160s E.3.161, and
E.3.162). Three of these locations are tree-nests
and one is the sole cliff-nesting location known to
be used by bald eagles in the Susitna River drainage.
(Bald eagle cliff-nesting locations are relatively
rare throughout Alaska north of the Alaska
Peninsula--for instances in the entire Tanana River
drainage where over 40 nesting locations are known
[Roseneau et al. 1981]s only one nesting location is
on a cliff.) Furthermores almost all suitable white
spruce and balsam poplar trees in the general
vicinity of Watana are located within the impoundment
area on tributary deltas and islands. Construction
and filling of Watana will likely limit bald eagles
to one or two available nesting locations along the
Susitna River upstream from the impoundment and one
or two potential locations along the lower Oshetna
River. This may increase the importance of other
potential nesting habitat downstream from the Watana
damsites including balsam poplar stands along Portage
Creek and white spruce and balsam poplar near Stephan
Lake and along Prairie Creek. In any event, it
appears unlikely that habitat loss as a result of
construction and filling of the Watana reservoir will
have more than a 1 ocal effect on the Susitna River
E-3-446
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bald eagle population, the majority of which inhabits
the area downstream from Indian River (see Section
4.2.3[a]).
No known gyrfalcon nesting locations will be directly
lost as a result of the Watana project. However,
gyrfalcons often use nests constructed by other
cliff-nesting species, including ravens and golden
eagles (Cade 1960, White and Cade 1971, Roseneau
1972), and some of the golden eagle and raven nesting
locations lost as a result of inundation or gravel
mining may represent past or future 1 ocat ions used by
gyrfalcons. In south-central Alaska and the Alaska
Range, where nesting densities are low (Roseneau
1972, Bente 1981, Roseneau et al. 1981), use of other
species• nests by gyrfalcons is less prevalent than
in northern and western regions of the state where
the majority of the Alaska gyrfalcon population
breeds and winters (see Roseneau et al. 1981). It is
therefore unlikely that habitat loss as a result of
construction and filling of the Watana reservoir will
have more than minimal effect on the middle Susitna
River gyrfalcon population.
One of three (33 percent) known goshawk nesting loca-
tions in the middle basin will be lost to clearing
and filling of the Watana reservoir (Figure E.3.115,
Tables E.3.160, E.3.161 and E.3.162). This nest
location is the only one discovered to date upstream
from the Watana damsite, beyond which typical goshawk
nesting habitat becomes very scarce (Roseneau 1982
Personal communication).
Eleven of 21 (52 percent) previously used raven nest-
ing locations in the middle basin will be lost as a
result of construction and filling of the Watana
reservoir (Figure E.3.115, Tables E.3.160, E.3.161
and E.3.162). Ten will be lost by inundation, and
one additional nest (R-4) may be inundated at times
of maximum flood stage (see Figure E.3.115) or be so
close to maximum operating water level as to be
unusable.
Although a considerable number of raven nesting
locations and cliff habitat will be lost, the
consequences of this 1 oss to ravens wi 11 be minor in
comparison to those for other cliff-nesting species
(particularly golden eagles). Ravens commonly nest
in a wide variety of situations in Alaska, including
E-3-447
4.3 -Impacts -Watana
man-made structures (Roseneau et al. 1981). Tree-
nesting in balsam poplar, aspen, and white spruce is
common, and ravens consistently nest on small cliffs
that are often unsuitable for raptors (Roseneau 1982
Personal communication). Construction and filling of
Watana without development of Devil Canyon is like1y
to result in increased use of cliffs along Devil
Canyon and trees along the river and tributaries
downstream from the Watana damsite rather than a
reduction in the middle basin raven population.
- Hunting and Perching Habitat
In addition to loss of nesting habitat, it is
anticipated that some loss of perching and hunting
habitat for raptors will occur as a result of
construction and filling of the Watana reservoir.
Perching habitat will be lost primarily as a result
of inundation of cliffs (see Table E.3.159) and the
clearing of trees prior to reservoir inundation.
Most of these losses will occur concomitantly with
losses of nesting habitat. Losses of perches,
whether by inundation (cliffs and trees), materials
excavation (cliffs and trees), clearing (trees) or
blowdown (trees), are considered of minor conse-
quence relative to losses of nesting locations.
Man-made structures, especially transmission towers
and smaller power poles, will also compensate in
part for 1 osses of perching habitat, because rap-
tors commonly use such structures as perches to
hunt from.
Loss of hunting habitat is more difficult to deter-
mine. No data were collected in the middle basin
to determine raptor hunting ranges and foraging
areas; however, losses of hunting habitat are
almost certainly to be of minor consequence, rela-
tive to losses of nesting habitat. Most raptors
are limited by availability of nesting locations
and nest sites, not food (Newton 1979). Further-
more, raptor "hunting habitat" and productive areas
of prey habitat, including riparian zones and wet-
lands, are not necessarily equivalent.
Habitats such as riparian areas and wetlands are,
of course, important because they tend to produce
and concentrate prey species. However, areas that
produce prey usually provide escape cover for the
E-3-448
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-4.3 -Impacts -Watana
prey species that inhabit them. Some of the most
important hunting habitat for many raptors is often
overlooked because of confusion regarding nesting
location, nest-site limitations vs. food limita-
tion, and because 11 hunt i ng habitat.. is commonly
assumed to be equivalent to areas of rich prey
production. Some of the most important hunting
habitat for many raptors consists of the three
dimensional 11 gulf 11 of air over rivers, lakes,
unvegetated or little vegetated terrain, or over
forested valley floors in mountainous terrain.
Peregrine falcons provide an excellent example.
Peregrines hunt and capture much of their a vi an
prey over water in front of and to the sides of
their river cliff-nesting locations as wetland,
forest, and shrubl and birds attempt to cross it.
Thus, some of the very best peregrine nesting and
hunting habitat in the boreal zone is found only
along larger rivers (e.g., Yukon, Tanana), regard-
less of varying and diverse prey habitats and
despite the fact that similar cliffs may be present
along narrow side tributaries.
For other species of raptors forest clearings, open
meadows and open mat-cushion tundra serve in a
similar fashion as important hunting habitat. Most
raptors, and especially the larger species, have
the capability to range relatively long distances
from their nesting 1 ocat ions to hunt. Thus, 1 oss
of hunting habitat as a result of construction and
operation of the Susitna Hyd roel ectri c Project is
unlikely to be of major consequence to most raptors
inhabiting the Susitna drainage. Loss of hunting
habitat wi 11 be compensated for in part by the
creation of the long, relatively narrow impoundment
over which potential prey species will pass. It is
also unlikely that loss of any prey production
habitat in the impoundment zone will be of a scale
that wi 11 be of major consequence to most raptors
inhabiting the middle and upper Susitna basins.
The general degree of impact may be inferred from
the data presented in Section 4.2.3(a); and addi-
tional information on hunting habitats of three of
the prominent species found in the middle basin
given below.
E-3-449
4.3 -Impacts -Watana
.Golden Eagles
Golden eagles probably hunt throughout the middle
and upper basins. However, they may avoid
heavily treed areas, con cent rating their effort
above and outside of the impoundment area rather
than in it. A tendency to hunt over open tree-
less areas, coupled with their varied diet that
includes several upland species, suggests that
the loss of hunting habitat caused by the project
will have minor effects on golden eagles •
• Bald Eagles
Bald eagles may hunt throughout the middle basin;
however, they tend to spend greater amounts of
time at lower elevations near water bodies than
golden eagles. Losses of hunting habitat to bald
eagles nesting in the middle basin may therefore
be greater than 1 osses to golden eagles. How-
ever, some attraction of waterfowl to open water
behind the dam or in the river downstream of it
in early spring may compensate in part for some
losses. Open water downstream from the Watana
dam may provide important wintering habitat from
the Watana dam in an area in which none currently
exists. At least a few bald eagles have over-
wintered in similar habitat along the Tanana
River in mild winters (Ritche 1974). However,
the Watana impoundment, with its large drawdown
and consequent lack of aquatic vegetation, is not
anticipated to be particularly attractive to
waterbirds as feeding habitat. On the other
hand, bald eagles in the middle basin are almost
certainly more limited by availability of nesting
habitat than by avai 1 ability of food. Assuming
water fowl are never attracted to the impound-
ment, and that fisheries never develop there,
surrounding habitat, including tributaries and
water bodies near the impoundment zone, is likely
to be adequate for those eagles that remain after
construction and filling of the Watana
reservoir •
• Gyrfalcons
Gyrfalcons may also hunt throughout the middle
basin, but they tend to avoid wooded areas and
probably concentrate their effort well above the
E-3-450
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4.3 -Impacts -Watana
( i i )
impoundment zone. Their tendency to hunt in
open, treeless areas including the alpine zone,
coupled with their opportunistic nature, suggests
that the 1 ass of hunting habitat as a result of
construction and fi 11 i ng of the Watana reservoir
will not be a serious impact.
Disturbance
Bald eagles and gal den eagles are specifically pro-
tected under the U.S. Bald Eagle Protection Act of
1940 (as subsequently amended). A part of this act
prohibits the "taking" of any bald or golden eagles,
parts thereof, or the nests or eggs of such birds
without a permit. "Take" is defined to include
molest or disturb.
The act does not authorize the taking of bald eagle
nests which interfere with resource development or
recovery operations. Take may only occur for scien-
tific or educational purposes at the discretion of
the Regional Director (USFWS). Recently an amendment
to the Bald Eagle Protection Act was drafted ( 16
U.S.C. 668a) that allows golden eagle nests to be
'taken if they interfere with resource development or
recovery operations. However, regulations pertaining
to this amendment are not yet available. Clearly,
the taking of eagle nests as a result of the project
must be addressed and mutually agreed to in consulta-
tion with the Alaska Region a 1 Director of the USFWS
before the project can be built. Such consultation
was initiated on February 1, 1983, in a letter from
the Alaska Power Authority, to K. Schreiner, USFWS
Area Director, Alaska.
In addition, there are state laws that provide
similar protection for these and other raptor
species. The Alaska Department of Fish and Game has
also developed guidelines to protect rapt or nests
from destruction or disturbance.
Roseneau et al. (1981) reviewed and summarized most
of the information on kinds and effects of disturb-
ance to raptors. Most information is anecdotal.
Responses of raptors to various types of disturbance
are complex--several factors may affect the sensi-
tivity of raptors to disturbance (Table E.3.163) •
Timing of the disturbance is an important factor
E-3-451
4.3 -Impacts -Watana
(Table E.3.164), and effects of disturbance may be
additive.
Responses of raptors to disturbance and the effects
of these responses are often highly variable. In
many cases, nesting raptors have shown a surprising
degree of tolerance and habituation to disturbances;
yet in other cases, the same types and 1 evel s of
disturbance have had detrimental effects (Roseneau
et al. 1981). In general, a mounting body of
evidence suggests that raptors will habituate to and
tolerate at least moderate forms of disturbance. The
same body of evidence suggests that the most
detrimental forms of disturbance are those that occur
within territorial defense zones (i.e., nesting
locations). Prolonged disturbances, multiple
disturbances, and direct overt harassment from either
the ground or the air are particularly harmful.
Some species of raptors appear to be less tolerant of
disturbance than others. Of species in Alaska,
golden eagles appear to be the most sensitive,
especially to aircraft disturbance and human presence
(see Roseneau et al. 1981). Although golden eagles,
like most raptor species, are reluctant to flush from
nests as a result of aircraft passage during
incubation, they often 1 eave their nests we 11 in
advance of approaching aircraft during the nestling
period (Roseneau et al. 1981). Furthermore, they
often leave their nesting areas quickly when people
approach, often at considerable distances (e.g., as
much as 0.5 miles (0.8 km); Roseneau Personal
communication) from the nest. Several documented
nesting failures of golden eagles in some areas have
been blamed on human interference (Roseneau et al.
1981).
Nesting locations of raptors and ravens that may be
subject to disturbance by the construction and
filling of the Watana reservoir are listed in Table
E.3.162. Nesting locations were selected for
inclusion on the basis of distance from project
actions. Judgments as to the genera 1 1 evel of
disturbance were made on the basis of nest elevation
above potential disturbance, distance to the
disturbance, and general nature and scale of the
disturbance, assuming year-round activity (clearing,
material excavation and dam construction).
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Seven golden eagle nesting locations within or on the
edges of the Watana impoundment may be susceptible to
disturbance from reservoir clearing operations (see
Figure E.3.115 and Table E.3.162: the exceptions are
GE-7 and GE-10}. Five of those locations will be
inundated later. Two of the five locations will also
be susceptible to considerable disturbance from
ma~erial excavation at Watana Borrow Site J (see
Table E.3.162; however, both locations (GE-8 and
GE-9) will be in undated. An eighth go 1 den eagle
nesting location (GE-11) will probably be physically
destroyed by material excavation unless some action
is taken to specifically preserve it (e.g., the
establishment of a buffer zone limiting excavation to
areas outside a radius .of at least 300 feet from the
nest cliff).
Four bald eagle nesting locations within the Watana
impoundment are susceptible to disturbance from
reservoir clearing operations (see Figure E.3.115 and
Table E.3.162: the exceptions are BE-l and BE-6}.
At 1 east two of the four 1 ocat ions are tree-nests
that will eventually be flooded (BE-3 and BE-5}, and
one is a cliff nest that will eventually be inundated
(BE-4}. The fourth location (BE-2) is also likely to
be inundated or may be 1 ost because of shore 1 i ne
erosion unless specific safeguards are taken.
No known gyrfalcon nesting locations appear suscept-
·ible to major disturbance from Watana construction;
however, one location (GYR-1} may be susceptible to
some disturbance during reservoir clearing.
At least one known goshawk nesting location will be
susceptible to disturbance from reservoir clearing
(GOS-1); this nest will eventually be inundated
(Figure E.3.115}. A second nesting location (GOS-2)
is located in the Devil Canyon reservoir, but may be
susceptible to some disturbance as a result of mate-
rial excavation at Watana Borrow Site I (see Table
E.3.162).
Twelve common raven nesting locations within or on
the edges of the Watana impoundment may be suscep-
tible to disturbance from reservoir clearing opera-
tions, but as many as 11 of them will eventually be
inundated (see Figure E.3.115 and Table E.3.162: the
exception is R-1). Three of the locations (R-9, R-10
and R-11) that will eventually be inundated will also
E-3-453
4.3 -Impacts -Watana
be susceptible to considerable disturbance associated
with material excavation at Watana Borrow Site J (see
Table E.3.162). Two other nesting locations (R-14
and R-15) are located downstream from the Watana dam-
site, but they may be susceptible to considerable
disturbance during excavation of materials from
Watana Borrow Site H. (This site will probably not
be mined.)
(o) Waterbirds
Because of the low numbers of waterbirds in the Susitna
Basin (Section 4.2.3[b]), impacts from the Watana develop-
ment will not have a major effect on regional populations.
Waterbirds of the basin will be affected during construction
of the Watana development by loss of habitat, alteration of
habitat and disturbance.
(i) Habitat Loss
Loons, grebes, swans, and several duck species in the
Susitna Basin occur primarily on lakes (Appendix 3E).
Most species will not be affected seriously by loss
of habitat since only 94 acres {38 ha) of lakes (0.2
percent of total in Gold Creek and Watana watersheds)
of 1 akes wi 11 be flooded by the Watana impoundment.
However, some species will suffer a permanent loss of
breeding habitat in fluviatile shorelines and
alluvia: harlequin duck, common merganser, semi-
palmated plover, spotted sandpiper, wandering
tattler, and arctic tern. Common goldeneyes and
mergansers wi 11 lose nesting trees during reservoir
clearing. Mergansers will nest on banks and other
locations in the absence of cavities. Goldeneyes
prefer to nest in relatively large diameter cavities.
Prince (1968) reported the smallest cavity diameter
in his study of common goldeneyes to be 6 inches
(15. 2 em). Most 1 arge trees are on the 1 ower slopes
of the Sus itna Valley and will be flooded. Open
water in fast-flowing streams and in the main
channel itself provides winter habitat for the dipper
of which a significant portion may be lost.
During filling, the sandbars, islands, and shorelines
used by shorebirds will be flooded. Two breeding
species (spotted sandpiper, and semipalmated plover)
and about seven migrant species will be affected.
The Susitna River does not support many migrant
shorebirds and the loss of habitat for migrants will
E-3-454
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(ii}
not be serious. However, all of the shorebird breed-
ing habitat in the impoundment area will be lost.
Habitat Alteration
During construction and filling, habitat alteration
will occur primarily from clearing and flooding of
shorelines. Clearing of forest will have little
effect on waterbird habitats with the possible excep-
tion, as noted in the previous section, of cutting
nest trees. Flooding will probably affect harlequin
ducks and fish-eating common and red-breasted
mergansers through some 1 oss of food resources.
Mainstream fish populations downstream are not
expected to be seriously affected by flooding, but
port ions of the grayling populations in tributary
streams may be lost (Section 2.3). Nevertheless,
fish populations above impoundment 1 evel will
probably remain sufficient to support the low
merganser numbers in the area, and this impact will
not be measureable.
Open-water a rea s be 1 ow the dam and near the intake
will provide habitat for spring migrants when other
water bodies are still frozen. The reservoir will be
of low quality to nesting waterfowl, but will provide
loafing habitat for migrating waterfowl and, in the
drawdown zone, feeding habitat for migrant shore-
birds, whose main movement passes through central
Alaska during the last three weeks of May. Feeding
habitat for fall migrants will not be available as
the reservoir will be full during that period.
(iii} Disturbance
A number of ·sources of disturbance to waterbirds wi 11
exist during Watana construction. The main sources
of disturbance will be borrow extraction from wetland
areas, transport of borrow and other materials, and
reservoir clearing. The construction of the dam it-
self is such a sufficiently localized disturbance
that few waterfowl will be affected.
Waterbirds in tundra areas have been shown to avoid
immediate areas of intense human activity (Barry and
Spencer 1976). Similar avoidance may occur in other
areas of open wetland. Clearing of the impoundment
area, especially near the river and its tributaries
and near wetlands and lakes, will be the most serious
disturbance factor for most waterbirds. Clearing and
E-3-455
4.3 -Impacts -Watana
associated heavy machinery traffic will physically
destroy nests of some species if conducted between
May and July. Disturbance will be intense during
clearing operations, and many species will be
affected.
Results of studies of the effects of aircraft distur-
bance on ducks {Goll op et al. 1974, Schwei nsburg
1974, Schwei nsburg et al. 1974, Ward and Sharp 1974)
have found changes in behavior, but little short-term
effect on distribution of nesting or moulting ducks.
Except at Stephan Lake, geese and whistling swans
occur in only small numbers during migration in the
Susitna area and are unlikely to be much affected by
disturbance. Trumpeter swans nest in the middle
basin; however, Kessel et al {1982a) report only one
nest in the Fog Lakes area. Two other swan nests
have been reported in the development area by R.
Fleming {1983 pres. comm.); one on the east fork of
Wakana Creek and are on the North Fork of the
Talkeetna River approximately 5-10 miles downstream
from the confluence with Prairie Creek. Other nests
may occur in the area, although the majority of the
basin population nests well to the east of the pro-
ject area, and only small numbers occur in the Watana
area during migration. Trumpeter swans are known to
be sensitive to disturbance during the nesting and
fledgling periods and any nests which occur in the
project area would be adversely affected by even
casual human intrusion {Hansen et al. 1971). Geese
do not nest in the basin and are uncommon during
migration; they are unlikely to be seriously affected
by disturbance.
{p) Other Birds
(i) Construction
Terrestrial birds wi 11 be most affected during con-
struction by habitat 1 oss through clearing of the
impoundment area, access roads, camps, borrow pits,
and other facilities. Clearing of the impoundment
area will affect the largest number of birds and will
result in changes in the distribution and relative
abundance of species in the area. Forest species
will be replaced by birds of shrub and open habitats.
Artificial habitats will be created for those species
which wi 11 use them. Another impact to birds near
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construction zones is sensory disturbance from
traffic, noise, dust, and people.
-Habitat Loss
Proportionate losses of various vegetation types to
the Watana project are presented in Table E.3.82.
The most severely affected vegetation types will be
forest types; in particular, open birch, closed
birch, and closed balsam poplar forest types. Open
and closed mixed conifer-deciduous forests, open
spruce forests, and woodland spruce forests wi 11
also be severely affected. The 12 census plots
studied by Kessel et al. {1982a) represent an over-
view of the terrestrial avian habitat types present
in the middle basin. The bird census study plots,
their avian habitat equivalents (as provided by
Kesse 1 et a 1 • 1 982a) , and approximate vegetation
type equivalents are presented in Table E.3.139.
Table E.3.165 presents the proportionate loss of
vegetation type equivalents to the avian habitats
represented in the census plots resulting from the
Watana project.
Habitat is a vague concept which attempts to pro-
vide biologically meaningful explanations of where
animals are found. Because habitat comprises both
biotic and abiotic factors, habitat suitability for
a given species and vegetation type (i.e., Viereck
and Dyrness cl assifi cations) can be expected to be
imperfectly carrel a ted. Attempts have been made
{through Principal Components Analysis, and related
Ordination techniques) to define "habitat" for
individual species by measuring numerous biotic
and/or abiotic variables and correlating derived
abstract factors with the distribution and use
patterns of each species. Although such analyses
are of great theoretical interest, they generally
fail to provide the kind of information required
for an assessment of impacts.
Although they are a crude approximation to actual
avian habitat, the loss of vegetation types pro-
vides the only available measure of the impacts of
the Susitna project on most terrestrial avian
species. Kessel et al. (1982a) provide 2 cautions
in the use of Viereck and Dyrness vegetation types
as avian habitats: (1) Viereck and Dyrness "tall
shrubland" supports two more or less distinct avian
E-3-457
4.3 -Impacts -Watana
communities (medi urn and tall shrub birds of Kessel
[1979]), and (2) Viereck and Dyrness closed coni-
ferous and deciduous forests (with a minimum of 75
percent closed canopy cover) are not restricted
enough for true coniferous or deciduous forest bird
communities (which require at least 90 percent
coniferous or deciduous components in the canopy,
according to Kessel et al. 1982a). If this is the
case, loss of 0.4 percent of the combined Gold
Creek and Watana watersheds ta 11 shrub vegetation
will affect two avian communities, medium shrub
birds and tall shrub birds (see Table E.3.140).
Also, loss of mixed conifer-deciduous forest may
underestimate loss to the mixed conifer-deciduous
forest bird community while loss of coniferous
forests and deciduous forest may overestimate the
loss to the coniferous forest and deciduous forest
bird communities (see Table E.3.140).
As shown in Table E.3.165, with the exception of
low mixed shrub, proportional losses are greater
for the most dense 1 y occupied vegetation types.
Although much overlap in species use of vegetation
types occurs, species restricted primarily to deci-
duous and mixed forests will be most severely
affected. These include spruce grouse, hairy and
downy woodpeckers, alder flycatcher, blackcapped
and boreal chickadees, brown creeper, varied,
hermit and Swa i nson • s thrushes, yell ow-rumped and
blackpoll warblers, northern waterthrush, and
dark-eyed junco.
Kessel (unpublished tables) provided an estimate of
numbers of breeding birds of each species 1 ost
based on 1981 density data and general observations
in the project area. These estimates, in Table
E.3.166, are considered approximate order-of-
magnitude figures. The total loss of breeding
birds of these species is 82,500 for the Wakana
facility alone, 4 percent of the total population
within 16 km of the Susitna River between the
Mclaren River and Gold Creek. Largest numerical
losses will be for species which occur in high den-
sities in a range of vegetation types and include
Swainson•s thrushes, ruby-crowned kinglets, yellow-
rumped warblers, Wilson•s warblers, dark-eyed
juncos, and tree sparrows. However, most of these
species are abundant throughout the middle basin.
The highest proportional losses will occur to
E-3-458
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4.1 -Impacts -Watana
. species restricted to these vegetation types which
suffer the highest proportional losses and include
spruce grouse, hairy woodpecker, boreal chickadee,
brown creeper, and northern waterthrush.
-Habitat Alteration
Habitat alteration resulting from clearing and con-
struction of buildings, dams, and borrow sites will
have negative effects on some species and positive
effects on others. For species which are
restricted to forest habitats, development-related
alteration will represent effective habitat loss
(see above discussion). Species found in closed
forests will be reduced in numbers near those
clearings which are in forested habitat. Areas to
be affected by temporary facilities and borrow
sites are relatively small, discrete areas and with
or without reclamation will eventually result in
openings of early successional habitats. Species
associ a ted with edges and disturbed or artificial
habitats will increase in these areas. Clearing of
forest vegetation may increase bird species diver-
sity through the creation of a different habitat
· type and associ a ted edge effects, depending on the
size of the clearing (Anderson et al. 1977). How-
ever, some researchers have found no true edge
effect (Kroodma 1982), and others have found a
decrease in diversity (Anderson 1979) because of
transmission line clearing through forested areas.
Since forest vegetation in the Susitna basin sup-
ports a somewhat higher diversity of birds than
shrub vegetation (Table E.3.138), there may be a
decrease in bird diversity as the result of forest
clearing.
Some species are capable of utilizing artificial
habitats created by man and these species may bene-
fit from certain habitat changes. For example,
bank swallows and kingfishers may dig their nest
cavities in sand walls of borrow sites that are not
in active use or even in less disturbed areas of
large sites that are in active use. Cliff swallows
readily nest on buildings. Ravens and gulls will
feed at refuse dumps if these are not properly
maintained.
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4-3 -Impacts -Watana
-Disturbance
Disturbance to terrest ria 1 birds will resu 1t pri-
marily from road traffic and is discussed in
Section 4.3.3(c). Some disturbance may also result
from activities of people at borrow sites and the
construction site, but there is little quantitative
information about the effects of such disturbance.
Local disturbance of this nature will not have any
serious effect on overall populations of terres-
trial birds.
(ii) Filling
Si nee the reservoir is to be cleared, most of the
habitat loss associated with the Susitna project will
occur during the construction phase and was discussed
above. During filling, the species that will be
affected are those that had invaded the cutover area
(mainly birds of shrub habitats) and birds dependent
on shorelines, mudbars, and streams. These latter
species are primarily shorebirds and the dipper.
Dippers inhabit fast-running streams; dipper breeding
and feeding habitat will be 1 ost to the extent that
the lower reaches of such streams are flooded (see
Chapter 2). Dippers also winter in the Susitna River
drainage along open-water of fast-running streams,
including the Susitna River itself. Open water in
winter at the dam intake zone is not expected to
serve as dipper habitat. Loss of open water in
winter throughout the impoundment zone wi 11 exclude
dippers from wintering there. However, the 1 arge
open-water reach below the dam in winter should
compensate for the loss of dipper wintering habitat
above the damsite.
(iii) Operation
The abundance and species composition of birds along
the downstream reaches of the river will change as
new riparian vegetation invades areas of the flood-
plain and proceeds through the successional stages
described in Section 3.3.1. These changes will be
most vi si bl e in the reaches upstream from Ta 1 keetna
where alteration of vegetation will be most pro-
nounced. Because bird densities and species diver-
sities are highest in tall shrub and mature forest
stands, the vegetation changes over 100-200 years
could be considered beneficial to terrestrial
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breeding birds. Howevert the proportionate changes
in species abundance in the study area as a who 1 e
will be very small during the license period.
(q) Non-game (Small) Mammals
Population densities of most species of small rodents fluc-
tuate widely under natural circumstances (Krebs and Myers
1974, Kessel et al. 1982a); it is consequently difficult to
predict postconstruction population levels. Although the
populations of some species will be diminished because of
the project, most species respond quickly to disturbance,
abandoning some areas and colonizing new ones. In additiont
reproductive rates of small mammals are high, and most popu-
lations can recover quickly from population reductions if
sufficient food resources and space are available.
Only those species of small mammals that are restricted to
forest habitats are expected to show marked decreases, pri-
marily because of loss of forest to the impoundment and con-
struction sites. These decreases may, in turn, be reflected
in changes in behavior and/or population levels of certain
carnivore or raptor species that depend on small mammals for
prey.
During the construction phase, small mammals will mainly be
affected by the clearing of the impoundment area, the borrow
sites and the construction camp. About 26,730 acres
(10,818 ha) of forest will be cleared. The species that are
restricted to forest habitats and will thus be most affected
are porcupines, snowshoe hares, pygmy shrews, and red
squirrels. Small numbers of hares and porcupines and
extremely small numbers of pygmy shrews were observed in the
project area. Because the area does not seem to be prime
habitat for· the former two species (Kessel et al. 1982a),
their regional densities are not expected to be affected by
the project. Red squirrels are common throughout the
forested areas of the project area. About 3.5 percent of
their preferred spruce habitat in the middle and upper qasin
will be cleared.
The other species that wi 1l be affected by clearing during
Watana construction will be the northern red-backed vole.
Red-backed voles were found in nearly every habitat type in
the Watana area, but were most common in spruce and cotton-
wood forests. A decrease of up to 5 percent in the overall
abundance ofthis species is expected.
E-3-461
4-3 -Impacts -Devil Canyon
During the three-year fi 11 i ng stage, many of the areas
cleared during construction will be colonized by early
successional plant species and small mammals. Meadow voles
are expected to thrive in such areas (Dabbs et al. 1974).
Tundra voles, masked shrews, and arctic shrews may also
recolonize these areas. As water levels rise during the
f·illing stage, these populations of small mammals will be
displaced. However, no substantial reductions in regional
populations are expected as a result of these effects.
The major impact on small mammals during the operation phase
of Watana Dam wi 11 be the changes caused by succession of
disturbed areas, such as the borrow sites and camps, and of
the newly exposed land downstream from the dam. Species
that occur in grasslands and early successional communities
will be favored initially. These include meadow voles, and
in some cases, tundra voles, masked shrews, and arctic
shrews. As succession progresses to shrublands, the habitat
will improve for species such as northern red-backed voles
and masked shrews.
4.3.2 -Devil Canyon Development
(a) Moose
Because of steep topography and extensive mature forests in
the Devil Canyon area, fewer moose occur in this portion of
the Susitna Basin than in the area to the east of Watana
Creek (ADF&G 1982a). Distributions of moose observed during
surveys in March 1981 suggest that moose were not common in
the vicinity of the Devil Canyon damsite but became more
abundant in upstream areas near the Watana damsite. ADF&G
( 1982a) estimated that 30 moose were present within the
Devil Canyon impoundment area during a census in late March
1981. The snow depth recorded at Devil Canyon at that time
was 29 inches; this census underestimates the number of
moose that would be present during winters with deeper
snows.
Because of the low numbers of moose in the Devil Canyon
area, impacts on moose in this region will be of smaller
magnitude than in the Watana development area. The range of
impacts to moose that may result from the Devil Canyon pro-
ject are similar to those already discussed for the Watana
project. Potential impacts include loss of habitat, alter-
ation of habitat, interference with seasonal movements,
mechanical and human disturbance, hazards associated with
the drawdown zone, and hunting mortality. Impacts
E-3-462
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associated with the access roads, the railway and transmis-
sion lines are discussed in Sections 4.3.3 and 4.3.4.
( i ) Construction
Construction of the Devil Canyon dam will involve
intense construction activity at the actual damsite,
establishment of a temporary camp, removal of forest
cover in the impoundment, and the excavation and
transportation of borrow material. The most impor-
tant effects of construction on moose will be habitat
loss, direct mortality, interference with seasonal
movements, and disturbance.
As discussed for the Watana project, alteration of
habitat resulting from construction activities will
be minimal and effects on moose will be negligible.
-Habitat Loss
An estimated 7907 acres (32 km2) will be cleared
within the Devil Canyon impoundment area and an
additional 529 acres (214 ha) will be used for
operational areas, campsites and borrow sites.
Losses of major forest cover types in relation to
their availability indicate that the greatest pro-
portion of losses will occur in woodland spruce,
open spruce, and mixed forest cover types (Table
E.3.83). Because moose in the Susitna Basin were
most commonly relocated in spruce forest than in
any other forest cover type (ADF&G 1982a), the 1 oss
of spruce habitat in the vicinity of Devil Canyon
may be important to moose. However, the limited
area of bottomland habitats and the steep slopes of
the Susitna River valley in the Devil Canyon area
probably limit present use by moose. Although
almost all of the low elevation habitat will be
lost, moose do not appear to commonly winter in the
Devil Canyon area, and the loss of low elevation
.habitats probably will not appreciably alter over-
winter survival of moose in the Devil Canyon area.
-Interference with Movements
The Devi 1 Canyon impoundment generally wi 11 not
exceed 1 mile (1.6 km) in width. Clearing of vege-
tation in the impoundment area may present a visual
barrier to moose movements, and disturbances asso-
ci a ted with clearing ope rat ions and construction
E-3-463
4-3 -Impacts -Devi 1 Canyon
could block or alter migration paths across or
along the river. Moose relocations in the Devil
Canyon area suggest that no major movement corri-
dors for moose exist within the Devil Canyon
impoundment area, but more frequent crossings may
occur once the Watana impoundment is present.
-Disturbance
Effects of disturbance on moose in the Devil Canyon
area will be minimal and will be similar to those
impacts discussed for the Watana project.
-Mortality
Although a few moose may be killed as a result of
collisions with vehicles or other accidents associ-
ated with construction areas, the effect of those
mortalities on moose populations will be negli-
gible. (Access road mortality is treated in
Section 4.3.3.) The major mortality factor asso-
ciated with the construction of the Devil Canyon
dam will be the probable increase in hunting asso-
ciated with the influx of construction workers and
other personnel to a previously remote area.
Because moose will be more abundant in the Watana
area than in the Devil Canyon area, hunting acti-
vity by Devil Canyon personnel wi 11 1 ikely be con-
centrated to the east of the project area. Effects
of hunting on moose are described in more detail
for the two development areas in Section 4.3.3(a).
(ii) Filling and Operation
The filling phase of the Devil Canyon impoundment is
estimated to be approximately 2 months (as opposed to
3-4 years for the Watana project). In addition, the
drawdown zone (to 50 ft [15 m] in some years during
August and September) wi 11 be 1 ess than 3 ft (1 m)
for most of the year. Because of the sma 11 er area,
local topography, the small drawdown zone during most
of the year, and the rapid filling sequence, the
effects of the Devil Canyon project on moose will be
much 1 ess severe than those of the Watana project.
The major impacts to moose will be alteration of
habitat, loss of habitat, blockage of movements,
direct mortality, and disturbance.
E-3-464
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-Alteration of Habitat
As discussed for the Watana project, the Devil
Canyon impoundment wi 11 cause some alterations of
vegetation in the vicinity of the impoundment and
in areas downstream from the dam.
Alteration of vegetation in the vicinity of the
impoundment may occur as a result of several micro-
climatic changes such as seasonal temperatures,
wind direction and speed, and ice fog. Effects of
these changes on moose wi 11 probably be undetec-
table (Section 4.3.1[a]).
Alteration of vegetation downstream from the Devil
Canyon site, however, may affect the distribution,
abundance, and quality of moose habitat. The com-
bined effects of the Watana and Devi 1 Canyon dams
will result in increased water temperatures in
downstream portions of the river, and it is antici-
pated that with both dams the Sus itna River will
remain open in winter from the Devil Canyon dam to
Talkeetna. Flow regimes following completion of
the Devi 1 Canyon dam are not expected to differ
greatly from flow regimes of the Watana project.
Hence, no additional differences in vegetation
resulting from lower water flows are expected when
the Devil Canyon dam becomes operational.
Open water in the Devil Canyon-Talkeetna reach of
the Susitna River will affect vegetation in several
ways. Steam fog will be common over the open water
reach during winter. Because of the high moisture
content of the air, icing of vegetation along the
river will occur. However, the area of riparian
habitat that wi 11 be affected depends on several
topographical and climatic factors, and cannot be
accurately predicted. It is also not known whether
plant productivity will be detrimentally affected
by icing or whether moose will utilize iced winter
browse. Although it is probable the icing of vege-
tat.ion will not make browse unavailable, it will
increase energy requirements of those individuals
that consume large quantities of ice. As a result,
impacts on moose associ a ted with vegetation icing
along the Devil Canyon-Talkeetna portion of the
Susitna River are difficult to quantify.
Because of the open-water conditions in the Devil
Canyon-Talkeetna reach, ice scouring of lower level
E-3-465
4-3 -Impacts -Devi 1 Canyon
riparian areas will be eliminated. Annual distur-
bance of successional growth in these areas will be
reduced (flooding will still scour some areas), and
the vegetation will begin to colonize the unvege-
tated band resulting from ice scouring during
operation of Watana only.
Riparian communities on higher ground of the river
channel wi 11 gradually succeed to cottonwood
forest, but at the same time will extend downward
into the newly exposed areas of the river channel.
Browse will increase in abundance along the river
once Devil Canyon is commissioned. However, such
browse may be partially unavailable, as described
in the following section, or of reduced value due
to icing, as described above.
-Interference with Movements
Movements of moose in the vicinity of the Devil
Canyon impoundment and downstream from the dam may
be affected by the Devi 1 Canyon project. Moose
attempting to cross the impoundment area may be
inhibited by visual factors such as the 1-mile
{ 1. 6-km) wide impoundment or the presence of open
water areas in winter. The width of the impound-
ment is not likely to present a physical barrier to
moose in summer, but winter open-water areas could
deflect movements.
Moose in the Devi 1 Canyon-Talkeetna reach of the
Susitna River overwinter in riparian habitats and
on river islands of the Susitna River (ADF &G
1982b). Parturient cows apparently prefer to calve
on river islands or in riparian areas, presumably
because of the availability of high quality forage
and reduced numbers of predators (Stringham 1974).
The presence of open water between the dam and
Talkeetna may interfere with use of these river
island habitats during the winter and the early
portion of the calving period. Moose in northern
British Columbia are not known to cross sections of
open water downstream from dams during winter (F.
Harper 1982 persona 1 communication). The effects
of exposure to sub-zero temperatures following
crossing of open water would presumably physiologi-
cally stress moose during a period when their
energy balance is already precarious. Browse and
cover occurring on islands must, therefore, be
E-3-466
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4-3 -Impacts -Devil Canyon
considered unavailable to moose for at least 3-5
months during winter.
-Disturbance
Mechanical and human disturbance should decline in
the Devil Canyon area once the dam becomes opera-
tional. Increased public access will maintain dis-
turbance at a higher level than is currently en-
countered, but at a 1 evel much lower than during
construction. If animals are not directly
harassed, disturbances during the filling and
operation stages will at most have a slight effect
on moose distributions.
-Mortality
During the filling and operation of the Devil
Canyon dam, moose mortality may increase as a re-
sult of hunting and accidental deaths (see Section
4.3.1[a]).
(b) Caribou
(c)
Few impacts of the Devil Canyon development on caribou are
expected. The impoundment area, particularly the area near
the damsite, has been infrequently used by caribou either
historically or in recent years. A small portion of the
Nel china herd may occasionally cross the impoundment, but
because the crossing hazards are expected to be less severe
than those associ a ted with the Watana impoundment, fewer
subtantial impacts are expected. There may be some impacts
on caribou resulting from aircraft disturbance and the
Watana to Devi 1 Canyon road segment--these wi 11 be similar
to those associated with the Watana development, and are
discussed in Sections 4.3.1(b) and 4.3.3(b).
Dall Sheep
The construction, filling and operation of the Devil Canyon
dam wi 11 have no direct impact on any of the three Da 11
sheep populations ih the middle Susitna Basin. All three
populations are far removed from the damsite.
Any increase in air traffic to the Watana airstrip caused by
the construction of the Devil Canyon dam has the potential
for disturbing the Mt. Watana-Grebe Mt. population (coming
from the south) or the Portage-Tsusena Creek population
E-3-467
4-3 -Impacts -Devil Canyon
(coming from the north). The effects of aircraft traffic on
Dall sheep are discussed in Section 4.3.1(c).
(d) Brown Bear
The impacts of the construction of the Devil Canyon dam on
brown bears will be similar to those during construction of
the Watana dam, except that the number of bears affected
will be much smaller. The area near the Devil Canyon site
is at 1 ower elevations and is not prime habitat for brown
bears.
Steep canyon walls will confine most of the Devil Canyon
impoundment, thus minimizing the area inundated. There will
be some loss of riparian areas, with their associated food
sources -berries, early spring vegetation, and moose
calves. No potential denning areas will be affected. Other
long-term effects of the Devil Canyon development, such as
increased hunting and aircraft disturbance, will be similar
to those associated with the Watana development, but at a
reduced seal e.
Some human/bear contact is likely to occur during the con-
struction of the dam, leading to increased bear mortality.
As discussed in Section 4.3.l(d), improper food and garbage
handling practices will increase problems with bears.
Avoidance of areas of human activity by bears wi 11 cause
some habitat loss, resulting in a lower carrying capacity
for brown bears.
(e) Black Bears
The impacts of the Devil Canyon development on the local
black bear population will be substantially less than those
for Watana, because only a small portion of acceptable black
bear habitat in the Gold Creek watershed will be lost. The
impact on denning areas will also be considerably less; only
one of 16 den sites (6 percent) found in the vicinity of the
Devil Canyon impoundment will be flooded. Most of the
potential impacts discussed for the Watana development will
exist, but at a much-reduced 1 evel. Downstream effects of
the Devi 1 Canyon impoundment should be the same as those
discussed in Section 4.3.1(e).
(f) Wolf
Impacts from the Devil Canyon development will be very Slml-
1 ar to those from the Watana development. No known dens or
rendezvous sites will be affected, and the loss of potential
E-3-468
4-3 -Impacts -Devil Canyon
den sites is not expected to have significant effects on the
wolf populations. Similarly, disturbance is not expected to
affect wolves except possibly at den sites during May and
June. Wolf pups moved from dens because of disturbance when
they are very young may not survive (ADF&G 1982f).
It was argued in Section 4.3.l(f) that wolf populations are
unlikely, at their present levels, to be seriously affected
by loss of prey species. The same situation holds for the
Devil Canyon development; only in the very unlikely event
that management objectives require higher wolf populations
would loss of prey species become a potentially significant
impact. Computer modeling of moose populations is being
conducted to assess the impact of a 1 tered predation rates,
increased accidents, and habitat 1 oss on moose. These
modeling efforts will also provide insight into possible
changes in predator/prey relationships.
(g) Wolverine
The effects of the Devil Canyon development on wolverine
will be i nsi gni fi cant except for the potential of increased
trapping as discussed in Section 4.3.3(g). Because wolve-
rines range over large areas, the relatively minor changes
in food availability and the effects of intensive human
activity near the canst ruction site shou 1 d not not i ceab 1 y
affect the few wolverines near the Devil Canyon development
area.
(h) Belukha Whale
( i )
As discussed in Section 4.3.1(h), the combined operation of
Watana and Devil Canyon should have no detectable effect on
belukha whales in Cook Inlet.
Beaver
The Devil Canyon project will have a net beneficial effect
on beaver. Several beaver colonies now occurring within
Borrow Site K and near the campsite will be adversely
affected, but an improvement in downstream habitat resulting
from more stable flows and a lack of ice cover downstream to
Talkeetna will offset these impacts.
No beaver are known to occupy the Devil Canyon reservoir,
and thus, no adverse impact is expected as a result of inun-
dation. However, during the period between the filling of
the Watana and Devi 1 Canyon reservoirs, some beavers may
colonize this reach and be initially displaced. If the
E-3-469
4-3 -Impacts -Devi 1 Canyon
reservoir level remains stable for several years as a result
of several wet years, beavers will successfully colonize the
impoundment. Beavers will probably attempt to colonize the
impoundment in other years, but the drawdown in August and
September will occur at a critical time when food caches are
being constructed and it is unlikely that beavers will suc-
cessfully overwinter. Approximately 10 beavers are known to
occupy the lakes in and adjacent to Borrow Site K and the
proposed construction camp, and these areas will probably
be lost during construction.
Downstream effects should be the same as with Watana, except
that the 1 ack of ice cover from Devil Canyon to Ta 1 keetna
will allow beaver use of some sloughs and side channels that
are subject to freeze-out when ice cover is present. The
mainstem may also be colonized once ice scouring is elimi-
nated.
(j) Muskrat
Construction of the Devi 1 Canyon dam shou1 d have no direct
impacts upon muskrats, since no suitable habitat is known
from the construction or borrow sites. Some habitat 1 oss
may occur from building camp facilities if ponds and lakes
are filled in for roads, work pads, etc. Downstream effects
wi11 be similar to those described in Section 4.3.1(j).
If construction camp personnel and their families are
a1lowed to trap in the area, muskrat populations throughout
the lakes lying on either side of the Susitna River could be
affected. Gipson et al. (1982) found muskrat sign in these
1akes and noted their vulnerability to trapping.
No impact is foreseen from vegetation removal in the im-
poundment zone or from subsequent flooding.
(k) Mink and Otter
Effects of the Devi 1 Canyon project on mink and otter wi 11
be similar to those already discussed for the Watana project
(Section 4.3.1[k]), but because of the smaller size of the
impoundment and the more stab1e water level, effects will be
1 ess severe. Because mink are most abundant east of Kosi na
Creek, the Devil Canyon project will probably have little
effect on the regional population. Major impacts to otter
and mink are 1 oss of habitat, reduction in prey ava i1 abi-
1 i ty, increased human disturbance, and barriers to move-
ment.
E-3-470
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-4-3 -Impacts -Devil Canyon
Because the combined c Devil Canyon. project and the Watana
project will result in permanently Open water from Devil
~ Canyon to Talkeetna, mink and otter may be positively
affected. Both species prefer areas of open water in rivers
and streams in winter (Barber et al. 1975). Open water
areas in the reservoir during winter should also have bene-
ficial effects.
....
r
I
{1) Coyote and Red Fox
(m)
Coyotes are more common in the Devil Canyon area than in the
Watana area, but they are still sufficiently uncommon that
the project is unlikely to have any effect on them. As in
the case of the Watana development, foxes will be affected
primarily by increased trapping and by destruction of nui-
sance animals if garbage is not regularly incinerated or if
regulations against feeding are not enforced. Habitat loss
will not be a major impact since foxes tend to occur at mid
and high e 1 eva ti ons rather than in the forested areas a 1 ong
the river.
Other Terrestrial Furbearers
Lynx, weasels, and marten will all be affected by the Devil
Canyon development primarily by loss of habitat. As in the
case of the Watana development, no estimates of the poten-
tia 1 reduction in numbers of wease 1 s can be made. Few if
any lynx wi 11 be 1 ost because of the poor habitat and
current low number. Habitat for approximately 14 marten
will be 1 ost to the impoundment and construction sites,
borrow sites, etc. If both Watana and Devil Canyon are
built, about 11.5 percent of the middle Susitna Basin marten
population will be lost (access road and transmission line
not included). Both of these estimates are based on the
conservative marten density derived in Section 4.3.1{m).
Marten, lynx, and weasels may be disturbed by construction
activity, but there is no evidence that they will vacate
areas as a result of these disturbances.
(n) Raptors and Ravens
( i) Construction and Filling
Construction and filling of the Devil Canyon reser-
voir waul d have simi Tar effects on raptors and ravens
to the Watana development, and would increase overall
impact to those species; however, the increase would
4-3 -Impacts -Devil Canyon
represent a relatively small proportion of the total
impact of both developments.
-Habitat Loss
One or possibly 2 of the 15 {12 percent) total
known golden eagle nesting locations in the general
vicinity of the Devi 1 Canyon impoundment wi 11 be
lost (Tables E.3.150 and E.3.152). The cumulative
1 oss of golden eagle nests to both projects repre-
sents 44-50 percent of known nest locations in the
project area (Table E.3.150).
No bald eagle nesting locations will be lost as a
result of Devil Canyon construction and filling.
No known gyrfalcon nesting locations will be inun-
dated by the Devil Canyon reservoir, but one of the
three total known locations may be located in
Borrow Site K (see Table E.3.150). If this nesting
location is indeed in Borrow Site K, it may be lost
during material excavation, though overall impact
to this species in the middle basin will remain
mini rna 1 •
One of three ( 33 percent) known goshawk nesting
locations in the general vicinity of the Devil
Canyon project will be lost to clearing and filling
of the Devil Canyon reservoir (Figure E. 3.115,
Tables E.3.150 and E.3.152). The nest location
that will be lost is one of two discovered to date
upstream of the Devil Canyon damsite. Although the
loss from this goshawk nesting location doubles the
number 1 ost as a result of both reservoirs, tota 1
impacts to this woodland species are anticipated to
remain minimal because appropriate nesting habitat
appears to be relatively limited in both impound-
ments.
Four of 21 (19 percent) previously used raven nest-
ing locations in the general vicinity of the Devil
Canyon project wi 11 be 1 ost as a result of con-
struction and filling of the Devil Canyon reservoir
(Figure E.3.115, Tables E.3.150 and E.3.152). All
four will be lost by inundation, and one additional
nest (R-19) will remain only a few meters above
maximum flood level (see Figure E.3.115).
E-3-472
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4-3 -Impacts -Devil Canyon
Although construction and filling of the Devil
Canyon reservoir wi 11 increase the number of used
nesting locations lost to 15 {71 percent of the
previous total) (see Table E.3.160), total impact
to ravens is still anticipated to be relatively
low. Loss of nesting locations in Devil Canyon
will probably increase the importance of remaining
cliff areas there (see Table E.3.161) and in side
tributaries. It may also increase the importance
of trees for nesting (see Section 4.3.1[n]).
-Disturbance
Five golden eagle nesting locations within or on
the edges of the Devi 1 Canyon impoundment may be
susceptible to disturbance from reservoir clearing
operations (see Figure E.3.116: the two exceptions
are GE-19 and GE-18). One and perhaps two of those
locations will be inundated later (GE-13 and
GE-14). One of the five locations (GE-11) may be
susceptible to disturbance from the clearing opera-
tions in the Devil Canyon area only if it remains
following the excavation of materials from Watana
Borrow Site E. One other gal den eagle nesting
location (GE-18) is about 0.6 miles (0.9 km) down-
stream from the Devil Canyon damsite and may be
susceptible to considerable disturbance as a result
of activities associated with the construction of
the dam itself.
No known bald eagle nesting locations appear sus-
ceptible to disturbance as a result of activities
associated with the construction of the Devil
Canyon dam, clearing operations within the impound-
ment zone, or filling of the reservoir.
Two known gyrfalcon nesting locations in the Devil
Canyon impoundment area may be susceptible to dis-
turbance. One of those locations (GYR-2) may be
susceptible to some disturbance during the reser-
voir clearing and the subsequent increase in human
presence as recreation activities develop and
increase along the impoundment edges. A second
location (GYR-3) may be susceptible to considerable
disturbance from excavation and transport of
materials from Devil Canyon Borrow Site K.
At least two known goshawk nesting locations (tree
nests) may be susceptible to disturbance from
E;..3-473
4-3 -Impacts -Devi 1 Canyon
construction and filling of the Devil Canyon reser-
voir. One of these nesting locations (GOS-2) is
within the Devi 1 Canyon reservoir. It may be sus-
ceptible to disturbance from material excavation
{0.13 miles [0.2 km] to the west) at Watana Borrow
Site I (see Section 4.3.1[n], [ii]) and will even-
tually be felled during reservoir clearing opera-
tions prior to inundation {Figure E.3.116). The
other nesting location {GOS-3) is situated well
above the reservoir 1 evel , but disturbance from
human presence may increase as recreational activi-
ties develop along the impoundment edges.
Six raven nesting locations within or on the edges
of the Devil Canyon impoundment may be susceptible
to disturbance from reservoir clearing operations,
but four of these will eventually be inundated (see
Figure E.3.116: the exceptions are R-19 and R-21).
One of the locations not inundated (R-19) will
remain only a few meters above maximum flood level.
The other nesting locations that is not inundated
(R-21) is about 0.47 mile (0.7 km) downstream from
the Devil Canyon damsite and may be susceptible to
disturbance during construction of the dam.
(o) Waterbirds
Initially the clearing and construction activities at Devil
Canyon may cause a temporary loss of suitable habitat for
waterbirds. The Devi 1 Canyon impoundment wi 11 have a rel a-
tively stable water level with a drawdown of only 1m for
most of the year (less than 1m in wet years). This should
allow for the development of some vegetation in the impound-
ment, although suitable shallow shoreline areas will be
somewhat limited. The open-water area near each end of the
reservoir should benefit some early and later migrants when
other waterbodies are frozen, and the relatively stable
water level in each year will allow a low level of use,
typical of large lakes of the region, for nesting by water-
birds along the shoreline. On the other hand, species of
alluvial and fluviatile shoreline habitats currently using
the impoundment area wi 11 be eliminated. Breeding habitat
for harlequin duck, common merganser, semipalmated plover,
spotted sandpiper, wandering tattler, arctic tern, and
dipper wi 11 be inundated. No si gni fi cant amount of shore-
bird feeding habitat wi 11 be created by the Devi 1 Canyon
impoundment because of the small drawdown and steep shore-
1 i ne.
E-3-474
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4-3 -Impacts -Devil Canyon
(p}
Downstream effects will be simi 1 ar to those discussed in
Section 4.3.1(o}. These will consist mostly of distribu-
tional shifts and minor changes in relative abundance of
riparian species as vegetation proceeds through the succes-
sional sequence described in Section 3.2.1.
Other Birds
The Devi 1 Canyon development wi 11 result in the same types
of impacts (habitat loss, habitat alteration, disturbance,
direct mortality) with the same effects on terrestrial and
shoreline birds as the Watana development (see Section
4.3.l[p]).
Flooding of the Devi 1 Canyon impoundment wi 11 increase the
proportionate loss of forest habitats in the middle basin by
several percent over that lost to the Watana development
(Table E.3.165). The largest losses will occur in closed
birch forests, conifer-deciduous forests and open spruce
forests (Table E.3.166). The total loss to the population
within 10 miles (16 km} of the Susitna River between the
Mclaren River and Gold Creek resulting from both Watana and
Devil Canyon Reservoirs and facilities is between 10 and 15
percent for the following species: spruce grouse, hairy
woodpecker, northern three-toed woodpecker, borea 1 chi cka-
dee, brown creeper, varied thrush, hermit thrush, Swainson•s
thrush, yellow-rumped warbler,blackpoll warbler and northern
waterthrush. For a few species, the proportionate loss to
Devil Canyon results in a substantial additional loss over
the Watana Development alone. Kessel (unpublished data}
calculated order-of-magnitude 1 osses for number of sma 11-
and medium-sized birds that would be 1 ost to the Devi 1
Canyon facilities (Table E.3.166). An estimated 17,300
breeding birds will be 1 ost to the De vi 1 Canyon fac i1 ity,
approximately 1 percent of the population within 16 km of
the Susitna River between the Mclaren River and Gold Creek.
As is the case for the Watana development, the dipper will
be affected by loss of breeding habitat in the lower reaches
of feeder streams and loss of winter habitat (open water) in
both feeder streams and the Susitna River itself. However,
open-water below the dam should compensate for this loss of
winter habitat.
(q) Non-game (Small) Mammals
The types of impacts on sma 11 mamma 1 s that wi 11 result from
construction of Devil Canyon dam will be similar to those
already discussed for the Watana dam (see Section 4.3). The
E-3-475
4-3 -Impacts -Access
major impact will be loss of habitat due to clearing opera-
tions and subsequent flooding. The total area affected
(approximately 34. km2, 8401 acres) and percent of forested
land affected (0.7 percent) are much smaller than in the
Watana reservoir area. The impacts on small mammals are
thus expected to be proportionately smaller.
4.3.3 -Access Roads and Railway
(a) Moose
Anticipated impacts on moose of the gravel access road from
the Dena 1 i Highway to the Watana dams ite and the 1 ater
construction and operation of the Devi 1 Canyon access road
include a loss of habitat, alteration of habitat, distur-
bance and subsequent avoidance of the highway, interference
with seasonal movements, and mortality. Moose will also be
greatly affected by the indirect impacts of the access road,
particularly hunting. Moose numbers will decline as a
result of hunting mortality and avoidance of the corridor by
moose. The railway from the Gold Creek area will have simi-
lar effects to those mentioned for the access roads, except
that hunting mortality should be lower (as a result of poor
vehicular access) and collision mortality during the winter
may be hi g her.
{i) Mortality
The primary impact of the access roads will be the
provision of improved public access to previously
remote areas in the Susitna Basin. In turn, improved
access will probably result in localized declines in
moose as a result of hunting and avoidance of the
highway corridor because of disturbance. Declines in
moose along newly opened roads or along roads in
areas opened for hunting have been reported for a
number of northern areas (Goddard 1970, Cumming 1974,
Ritchey 1974, Beak 1979). Although a good portion of
these declines in moose was the result of hunting
mortality, moose probably also avoid areas in the
vicinity of access corridors during the hunting
period.
A decline in moose numbers during construction of the
Watana access road can be expected as a result of
hunting. Effects would probably be most severe in
the vicinity of campsites or the townsite. Public
access to the Susitna Basin will increase once the
road is operational, and furth~r increases in hunting
E-3-476
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4-3 -Impacts -Access
pressure will occur with resultant increases in hunt-
ing mortality of moose. Because the moose population
will already be stressed by impacts associated with
the Watana development and the subsequent redistribu-
tion of moose within the Susitna Basin, disturbances
associated with hunting and hunting mortality may
further aggravate impacts to the moose population.
Because the Watana development will reduce the carry-
ing capacity of the Susitna Basin for moose, it is
possi b 1 e that moose numbers will temporarily exceed
those optima 1 for sustained productivity. Assuming
that surplus moose may be present, carefully managed
hunting may effectively mitigate for the indirect
project effect of overutil ization of remaining forage
(see.Section 4.4}.
Construction and operation of the Watana-Devil Canyon
access road segment and the railway will result in
simi 1 ar but 1 ess severe impacts on moose. The Devi 1
Canyon segment will provide new access to a relative-
ly smaller area, much of which is poorer quality
moose habitat than is the Watana dam area. The rail-
way wi 11 not provide as easy an access route to the
general public as the roadways, and its use can be
better controlled. Hunting pressure consequently
will not increase as in the case of the access roads.
In addition, much of the area that wi 11 be affected
by railway access supports relatively low numbers of
moose as compared to 1 ower reaches of the Susi tna
River.
During the construction and operation of the access
roads and railway, moose may be k'illed as a result of
collisions with vehicles. High volumes of road
traffic are expected along the Watana and Devil
Canyon access roads during construction of the dams
(primarily from workers commuting to the site), and
the number of moose killed will be substantial, par-
ticularly during winters of deep snowfall or when
darkness or poor weather results in poor vi si bi 1 i ty.
Collision mortalities along the railway could also be
substantial. ~n additional 8 train trips per week in
each direction are. expected during the construction
of the Devil Canyon dam. Rausch {1958) reported
adjusted kill totals of 366 and 179 moose along a
86.9 km section of the Alaska Railway (Houston to
Talkeetna) during the winters 1955-56 and 1956-57,
respectively. During the winters of 1970-1971
E-3-477
through 1978-79, annual moose kills along the Willow-
Talkeetna portion of the Alaska railway ranged from 0
to 151 animals (ADF&G unpublished data). Because
moose are easily trapped within the steep snow
embankments along rail way 1 i nes and are usual}y more
abundant in va 11 ey bottom habitats during winters
with high snows~ higher numbers of collision mortali-
ties occur along rights-of-way in low elevation areas
during severe winters.
ii) Loss of Habitat
Construction of the Watana and Devil Canyon access
roads and the railway will result in loss of habitat
associated with the construction corridor and borrow
pits. Although the actual removal of moose browse
will be small in relation to its availability in
other areas of the Susitna Basin, the effective loss
may be greater if moose avoid the access corridors or
if migration routes are blocked. As discussed above,
moose will tolerate disturbance along access corri-
dors if they are not hunted. However, if hunting is
permitted, moose may avoid an area of several kilo-
meters from the corridor, consequently increasing the
effective area of lost habitat.
Based on existing information, no special use areas
for moose such as wintering range, calving areas, or
breeding concentrations will be rendered unusable by
the road access corridors. However, because most
special use areas will be inundated by the impound-
ments, these road corridors could affect the location
of new special-use areas. Anticipating such changes
is obviously difficult.
The prob 1 em of rail way corridors in moose wintering
areas and resulting collision mortalities has already
been discussed.
(iii) Alteration of Habitat
Construction of the access road and railway will
necessitate the use of gravel berms that may impede
or alter drainage systems (Boelter and Close 1974,
Kemper et al. 1977). Permanent flooding of forested
areas may result in the 1 oss of some moose habitat
through killing of trees and shrubs. However, growth
of aquatic plants within flooded areas may partially
compensate for this loss by providing additional
E-3-478
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summer forage. Drainage of wetland areas may result
in a temporary increase in the growth of seral shrub
communities, but without periodic flooding or
disturbance, these areas will eventually develop into
forest stands with low browse production.
(iv) Interference with Seasonal Movements
The proposed road access corridors will cross several
areas where moose mig rate seasonally between summer
and winter ranges (ADF&G 1982a). Concentrations of
movements by radio-collared moose that may be affect-
ed by the Watana road include the Watana-Butte Creeks
area, and the Watana-Deadman creeks area (Section
4.2.1[a]).
During construction, mechanical activities may pre-
vent some moose from crossing the road corridors,
primarily as a result of moose avoiding the construc-
tion area. Avoidance of the road corridor would pro-
bably be most severe during the hunting season, if
hunting is permitted. Steeply sloped road berms and/
or the creation of deep snow embankments from road-
plowing may act as physical barriers to moose cross-
ings. As discussed earlier, the railway may inter-
fere with movements of moose during the winter and
early spring periods when snow embankments may either
b 1 ock movements by moose or trap animals within the
cleared right-of-way.
(b) Caribou
The access· road between the Denali Highway and the two dam-
sites is 1 ikely to have a substantial effect on caribou
movements. Few caribou movements have been recorded in the
area traversed by the Devi 1 Canyon to Watana dam segment,
and the western segment between the two dams and Gold Creek
should not pose a serious problem to caribou. The segment
between the Denali Highway and Watana dam, however, traver-
ses an historically important area of the herd•s range,
which is currently used by a resident subherd of up to 2500
caribou and also by some caribou from the main herd. The
road is most likely to affect the herd by increasing mortal-
ity from collisions with vehicles and from hunting, and by
altering movements between the area west of the road and the
remainder of the herd•s range. There may also be a slight
increase in wolf predation in the area, since wolves often
E-3-479
4.3 -Impacts -Access
use roads to their advantage while hunting caribou (Roby
1978).
Detailed information on the effects of roads and associated
human activities (e.g., vehicle traffic, construction acti-
vity, presence of workers) on caribou comes primarily from
four sources: (1) studies by the ADF&G along the TAPS
corridor since 1974, and along the Kuparuk oilfield access
road since 1978; (2) a two-year study by Fancy (in press) in
a floodplain area used by large numbers of caribou moving to
and from insect-relief areas; (3) data from a study by Roby
(1978), who worked with ADF&G along the TAPS corridor; and
(4) a two-year study conducted along the Kuparuk oilfield
access road by Curatolo et al. (1982). Alyeska Pipeline
Service Company is also funding a three-year study along the
TAPS corridor as a 11 Second opinion 11 to the ADF&G studies;
however, no reports have been re 1 eased after two years of
study. All of these studies involve the Central Arctic Herd
on Alaska • s North Slope.
The results of these studies are somewhat contradictory, and
as a result, caribou biologists disagree on the severity of
road effects on caribou. ADF&G studies (Cameron and Whitten
1979, 1980; Cameron et al. 1979) have concluded that caribou
cows and calves avoid the Prudhoe Bay oilfield, based on a
lower percentage of calves in caribou groups observed from
the roads in their study area as compared to aerial sight-
ings over a larger area. But, along the Kuparuk oilfield
access road (oriented E-W and thus not confused by latitudi-
nal biases), calf percentages have not been found to differ
from those expected in three years of study (Cameron et al.
1981). During an aerial calving survey along that road in
1980, no calves were seen within 2.7 miles (4 km) either
side of the road, but this was not the case in 1978 and
1979. Few calves have been born within the Prudhoe Bay
complex in recent years. The Central Arctic Herd has been
steadily increasing in size each year, and productivity has
been 11 excellent 11 (Cameron et al. 1981) in spite of the
localized effects on caribou distribution and group composi-
tion.
Recent detailed studies involving continuous observations of
caribou as they approach roads and pipelines have found that
most caribou will cross roads with light-to-moderate vehicle
traffic, but that caribou will often first try to find a way
around the obstacle (paralleling movements), and some groups
(10-14 percent for the most detailed study) may refuse to
E-3-480
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4.3 -Impacts -Access
cross at all (Fancy, in press). Preliminary results by
Curatolo et al. (1982) have found that the proportion of
groups that crossed the Kuparuk oilfield road and pipeline
was significantly less than that expected (control). Many
groups left their study area paralleling the road and pipe-
1 i ne, and thus the proportion of groups that eventua 11 y
crossed could not be determined.
The responses of individual caribou to roads and traffic are
extremely variab 1 e; some animals appear to avoid 1 i ghtl y
traveled· roads entirely, whereas others will cross roads
during rates of traffic exceeding one vehicle per minute
with no observable response. In general, however, moving
vehicles and/or the presence of workers will alter the local
movements and behavior of caribou. Horejsi (1981) reported
that 88 percent of the caribou he observed along the
Dempster Highway reacted to a moving pickup truck by running
or trotting away. A fleeing animal can expend eight to
twenty times the cost of basal metabolism, at the expense of
body growth, development, and reproduction (Geist 1975).
The greatest concern for disturbance effects on caribou is
for cows in late pregnancy and cows with young calves.
Female caribou are particularly sensitive to disturbances
during the calving period (Lent 1966, Bergerud 1974b, Calef
et al. 1976, Surrendi and DeBock 1976), and disturbances at
this time are more like1y to result in lowered recruitment
because of premature travel by calves, disruption of cow/
calf bonds, or trampling (Lent 1966, Geist 1971b, Bergerud
1974b, Surrendi and DeBock 1976). Some calving has been
documented north of the Sus itna River, but the road has been
realigned so that it is to the west of the areas where most
calving has recently occurred. Cows calving in the area may
avoid the road during the period of heavy use, but this will
affect only a small number of animals.
Large volumes of vehicle traffic are expected during peak
construction years, including 20 project support materials
vehicles per day, hundreds of trips per day by workers
driving to the site, and 70 project heavy trucks per day
(Table E.3.162). If the road is opened to the public during
or after construction, high traffic rates will continue.
The traffic volume during the caribou studies cited earlier
was only a small fraction of that expected during dam
construction. A few caribou wi 11 cross the road regardless
of high traffic frequencies, but the majority will probably
cross only if lulls in traffic are provided. Since the area
west of the road is currently a peripheral part of the main
herd's range, failure of most animals to cross the road will
E-3-481
4.3 -Impacts -Access
not cause a major impact. As the herd increases in size,
however, the importance of the area to the herd will greatly
increase. It is thus important to design and operate the
road so as to permit free crossings by caribou during the
operation phase of the project.
The physical presence of a raised gravel road, in the
absence of vehicles and human activities, will not be an
insurmountable barrier to caribou movements (Surrendi and
DeBock 1976). The exception to this is that plowed or
blown snow along the road could, in combination with the
raised road surface, act as a physical barrier to caribou
movements (Surrendi and DeBock 1976). Caribou tend to
seleCt the lowest berms when crossing roads (Cameron and
Whitten 1976, Surrendi and DeBock 1976, Roby 1978), and
various studies have shown that caribou are wary of berms
they cannot see over (Hanson 1981).
The Nelchina herd has been important to both sport and sub-
sistence hunters because of its size and proximity to popu-
lation centers. In 1981, 6662 people applied for 1600 per-
mits to hunt for Nelchina caribou. The permit system cur-
rently in use will have to be continued if only the annual
increment is to be harvested as stated in the herd manage-
ment plan (ADF&G 1976). Public access provided by the
Denali access road wi 11 have a greater effect on the dis-
tribution of hunting pressure than it will on the actual
number of caribou harvested, since hunter success is cur-
rently very high. The Susitna-Nenana subherd is resident in
the access road area and, although the rate of exchange of
individuals with the main herd is unknown, the presence of
the Watana impoundment in conjunction with heavy hunting
pressure will probably result in a substantial decrease in
this sub herd.
(c) Dall Sheep
The effect of vehi c1 e traffic along the access road should
be insignificant, since sheep are not expected to occur
close to the roads. MacArthur et al. ( 1982) found that
only 19 of 215 documented passes (8.8 percent) of sheep by
vehicles evoked heart rate responses, usually of 1ow ampli-
tude. Moreover, 73.7 percent of all heart-rate responses
occurred when vehicles passed within 82 feet (25 m) of the
sheep. They reported that only 2 of the 215 vehicle passes
(0.9 percent) they recorded evoked withdrawal responses by
sheep. In Denali National Park, Tracy (1977) found that the
strength of reactions and the percentage of sheep showing
visible reactions to buses and visitors decreased with
E-3-482
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4.3 -Impacts -Access
(d)
increasing distances between the sheep and the road. She
recorded no reactions by sheep at distances exceeding
2460 feet (750 m) from the road, whereas strong reactions
were recorded only at distances less than 1312 feet (400 m).
Dall sheep have continued to use lambing and wintering areas
along the Dalton Highway (Hemming and Morehouse 1976, Fancy
1980), in spite of intensive pipeline construction and
vehicle traffic along that road. Disturbance due to air
traffice is treated in Section 4.3.1(d). Increased
disturbances from human access as described in Section
4. 3.1 (d) for the construction phase wi 11 also occur during
operation as recreational use of the area increases.
If the project area is opened to the public following con-
struction, there will likely be an increase in hunting
pressure in locations adjacent to the access roads and the
reservoir. The number of sheep harvested in the area is not
expected to increase greatly, however, because all or most
legal rams in the area are already being harvested each
year. Serious population depletions resulting from the
increased hunting pressure are thus not expected to occur.
Brown Bear
Both the Denali-Watana and Watana-Devil Canyon access road
segments traverse prime brown bear habitat. Potential
impacts of the access roads on brown bears include inter-
ference with movements, increased hunting mortality, and a
decrease in acceptable denning and feeding areas. Direct
mortality from hunting and nuisance animal control will pro-
bably have the greatest effect on the population in the long
term.
Tracy {1977) reported on the. reactions of brown bears to the
Denali Park Road. She found that the densities of bears in
study plots away from the road were consistently greater
than densities along the road, suggesting an avoidance of
roads by bears even where no hunting occurs. Many bears
have habituated to the road, however, and those seen near
the road were frequently engaged in such activities as nurs-
ing, playing, and sleeping, which suggests security and
relaxation. The literature also includes a paper by Elgmark
{1976), who reported that construction of a network of logg-
ing roads in Norway resulted in a lower density of brown
bears, and a report by Miller and Ba1lard (1982) on the
apparent short-term deflection of brown bear movements by
the Glenn Highway in Alaska.
E-3-483
4.3 -Impacts -Access
The access road is likely to cause some alterations in the
movements of brown bears, but there is 1 ittl e evidence to
suggest that it wi 11 block bear movements altogether.
Revegetation of the road shoulder will create forage which
is attractive to brown bears, especially during early
spring, when such areas will green-up earlier than
surrounding vegetation. However, because brown bears in the
middle basin are hunted, they are not likely to feed on
berries and other foods occurring adjacent to the road
during hunting season, and thus there will be a decrease in
the avai 1 ability of foods as a result of the road in that
season. Several dens have been found in the Denali Highway
to Watana access road segment. Brown bears in the project
area do not appear to re-use existing dens and the
availability of denning habitat does not appear to limit the
population. However, it is likely that brown bears will
find unacceptable the denning area used by three different
bears in 1980 and 1981 near the proposed road once the road
is present.
Abandonment of dens by bears in winter can result from human
activity near the den (Craighead and Craighead 1972a,b;
Harding 1976) or from disturbance caused by helicopters
(Reynolds et al • 1976). Frozen ground would then prevent
the bears from digging new dens. Disturbance of bears in
winter dens during road construction may cause the death of
several bears.
Although some brown bears are now harvested from the remote
areas of the middle basin, most hunting occurs along or near
the Denali Highway. The improved access resulting from the
road and reservoir will probably cause a large increase in
the number of brown bears killed by hunters in the basin.
Habitutated bears, particularly young bears, will become
particularly StJsceptible to hunting. Additional mortality
will occur from the destruction of habituated and nuisance
bears.
(e) Black Bear
The access road wi 11 impact black bears primari 1 y through
improved access for hunters. Black bears do not usually
occur near the proposed road north of the Deadman Lake area,
and much of the Watana-Devil Canyon segment is at elevations
above acceptable black bear habitat. Road construction
could cause abandonment of dens, particularly in the lower
Deadman Creek area and near the Devil Canyon damsite. The
probability of bear mortalities caused by collisions with
vehicles is very low.
E-3-484
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(f)
(g)
Wolf
The major effect of the access route on wolves wi 11 be an
increase in the numbers of hunters, trappers, and con-
struction workers able to shoot wolves in the area.
However, wolves may also be affected by disturbance from
construction activities and traffic, and small numbers may
be killed by vehicles. The number killed by vehicles is
likely to be greater if wolves become habituated to vehicles
through being fed. Since wolves do habituate readily to
traffic and noise under most circumstances, disturbance is
unlikely to have major effects. However, wolves appear to
be more sensitive to disturbance during the denning season.
Carbyn (1974) documented abandonment of two wolf dens near
highways after the roads were upgraded and traffic val umes
increased. The proposed Susitna access route passes through
the home ranges of at least three wolf packs. Two den sites
and one rendezvous site are known from the general vicinity
of the access route; additional sites most likely exist.
Impacts from increased access by hunters and trappers cannot
be quantified but may be severe. As many as 8-10 wolves per
year have been taken in the immediate vicinity of the pro-
posed impoundments since 1976-77 (ADF&G 1982f) in spite of
the relative inaccessibility of the area at present. In-
creases in the number taken may be beyond the capability of
the population to replace, or may reduce the ability of this
population to produce excess animals that presently disperse
to areas even more heavily hunted.
Wolverine
The direct 1 ass of habitat caused by the access road wi 11
have an i nsi gnifi cant effect on wolverine. Hornocker and
Hash•s (1981} statement that "the size and shape of
(wolverine home) ranges were not affected by rivers, reser-
voirs, highways or mountain rangesu suggests that the road
and associated traffic will also have an insignificant
effect on wolverine movements and availability of prey. It
is not clear whether wolverine will utilize carcasses of
animals killed by collisions with vehicles, but this is a
possibility, especially during periods of infrequent vehicle
use. The potential for wolverines to be killed by vehicles
is very low, considering the low densities of wolverine and
their wariness.
Increases in trapping pressure as a result of improved
access is more likely to affect wolverines than any other
E-3-485
4.3 -Impacts -Access
project-related activity. Wolverines are highly susceptible
to trapping because they travel widely and are readily
attracted to baits. Hornocker and Hash (1981) reported that
all of the wolverines they captured were missing one or more
toes, and many had broken teeth; many of these mut i 1 at ions
were attributed to encounters with leg-hold traps. Van Zyll
de Jong (1975) stated that .. predation by humans appears to
be the most 1 ike 1 y factor to have affected the number of
wolverines. Direct evidence of negative effects of human
exploitation on wolverine populations is not available, but
indirect evidence from declining production of wolverine
pelts and the disappearance of the species from areas with
relatively dense human populations strongly suggests that
exploitation by man contributed to the decline ... Fifteen of
the 18 known wolverine mortalities in Hornocker and Hash•s
(1981) study were human caused. Increased trapping pressure
in the Susitna Basin will probably cause some instability in
the social structure of the population, thus causing notice-
able shifts in home ranges. However, population effects of
trapping mortality waul d be difficult to detect because of
emigration of wolverine from the large parcels of wolverine
habitat surrounding the basin into the affected areas.
Wilderness or remote country where human activity is limited
appears essential to the maintenance of viable wolverine
populations (Van Zyll de Jong 1975, Hornocker and Hash
1981). However, Hornocker and Hash (1981) reported that
they found 11 no differences in wolverine density between the
wilderness and nonwilderness portions of our study area, nor
was wolverine movement, habitat use, and behavior different.
Marked wolverines used both areas and several individuals•
home areas overlapped both wilderness and nonwil derness.
The nonwilderness portion, about one half of the study area,
is used by humans primarily for logging and recreation;
1 oggi ng roads and foot trai 1 s provide access to river and
stream bottoms and lower elevations during summer and fall
months. Loggers, summer recreationists, and hunters make
considerable use of those areas ... They went on to say,
however, that wolverines and humans were effectively sepa-
rated because the wolverines were at higher elevations away
from people during summer and fall , and 1 ittl e use of the
area by humans occurs during winter when wolverines move to
the lower elevations. A similar situation will exist in the
middle Susitna Basin; the most intensive human use of the
area will occur in summer when wolverines are using
primarily tundra habitats. Access to these tundra areas
afforded by the roads and transmission corridors may cause
several wolverines to avoid portions of their range. Winter
E-3-486
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4.3 -Impacts -Access
use of the impoundment areas, except for trapping, should be
considerably less than that during snow-free periods.
(h) Furbearers
The construction of the access road and the railway will
result in some habitat 1 oss for terrestrial furbearers, and
may result in' habitat loss for aquatic furbearers if wet-
lands are degraded. Minor effects on the local distribution
of individuals of some species may also occur along the
road. For example, Hawley and Newby (1957) believed that
habitat openings were a psychological barrier to marten.
Although subsequent studies have found that marten regularly
cross openings 328-656 feet (100 to 200 m) wide (Koehler et
al. 1975, Soutiere 1978), the access route will result in a
redi stri but ion of home ranges, and many marten wi 11 be
forced to realign their home ranges along the road.
Similarly, some foxes may avoid the road area, but most will
probably habituate to traffic. Tracy (1977) found several
fox dens within 328 feet (100 m) of the road in Denali
National Park and observed foxes traveling along the road
while vehicles were using it. However, such habituation to
human presence probably occurs only in the absence of
trapping pressure. Access routing (Figures E.3.79 to
E.3.82) is very near several red fox denni ng complexes,
which, in the absence of mitigation could be made unusable
or be physically destroyed.
Access to the Watana site from the Dena 1 i Highway has the
potential to negatively impact large numbers of beaver.
Approximately 65 beaver occupy 12.3 miles (18.4 km) of upper
Deadman Creek, a relatively broad stretch along which the
access route is. proposed. Similar beaver densities may
occur in adjacent areas designated as material sites. Use
of the valley bottom for the road and material sites will
negatively impact at least 40 beaver.
Two opposing scenarios are reported in the literature on
possible effects of road construction on beaver habitat. In
one (Watson et al. 1973~, diversion or impoundment of stream
and subsurface water flows by roa.d berms has a negative
effect on downstream beaver ponds and lakes through the
introduction of heavy sediment loads and increased
turbidity. These are the effects of bank instability caused
by the clearing of riparian vegetation associated with
ri ghts-of..;.way constr.uct ion and maintenance. Heavy sediment
loads result in the gradual filling of downstream ponds and
E-3-487
4.3 -Impacts -Access
lakes; increased turbidity reduces light penetration and
inhibits growth of aquatic vegetation.
Alternatively, ponding at culverts and bridges and restric-
ted subsurface flows caused by road berms have often created
attractive sites for beaver colonization. The use of brid-
ges and culverts. as damsites by beaver is well documented
(Bradt 1947, Hodgdon and Hunt 1953, Huey 1956, Rutherford
1964, Johnson and Gunson 1976). However, habitat improve-
ment through the introduction of a road in prime beaver
habitat along upper Deadman Creek is unlikely, and a reduct-
ion in beaver numbers is expected there.
Muskrats along the proposed access routes wi 11 be affected
through habitat loss and increased trapping mortality.
Gipson et al. (1982) found sign of over wintering muskrats
in several of the lakes lying along the proposed route from
Watana dam to Devil Canyon dam. Many of these muskrats
occurred in conjunction with the high beaver densities noted
along the proposed route from the Denali Highway to Watana
dam.
In addition to being very sensitive to water level changes
which could occur because of draining or filling of ponds
and lakes (Bellrose and Brown 1941), the small foraging area
of muskrats, (usually within 32.8 ft [10m]) of their house)
makes them sensitive to loss of their preferred foods of
aquatic and emergent plants (Butler 1940).
No substantial effects are anticipated on mink or otter
populations with the possible exception of increased rec-
reational disturbance resulting from public access to
streams that may be important to these species.
The major impact of the access routes on furbearers is rela-
ted to the probable increase in trapping pressure. The
Susitna Basin is not heavily trapped at present and, for
some species, the area may be a source from which animals
disperse into more heavily trapped adjacent areas. The spe-
cies that will be most affected by increased trapping pres-
sure are probably marten, beaver, muskrat, and red fox.
Marten are the most economically important furbearer in the
basin; beaver and fox are also heavily exploited in adjacent
areas. Mink and otter may be affected to a 1 esser extent,
since they do not appear to be particularly desirable
species in this part of Alaska (Gipson et al. 1982).
E-3-488
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(i) Raptors and Ravens
(i) Denali Highway to Watana Damsite
( i i}
Some nesting habitat for ground-nesting raptors
(e.g., merl ins, northern harriers, short-eared owls)
may occur along the Denali-Watana section of the
access road and may be 1 ost; however, cliff-nesting
habitat does not appear to occur within at least a
few kilometers of the route, and only one tree-nest
appears to be associated with it (Roseneau 1982
Persona 1 Communication).
No golden eagles, gyrfalcon, goshawk, or raven nest-
ing locations will be lost as a result of road con-
struction between the Dena 1 i Highway and the Watana
campsite and Watana damsite.
One bald eagle nesting location (BE-6, see Tables
E.3.160 and E.3.162} in Deadman Creek will be physi-
cally destroyed by access road construction between
the Denali Highway and the Watana damsite. The
active nest is located in a balsam poplar tree in a
small stand of poplar and white spruce. The current
road alignment passes directly through the stand of
trees. This stand appears to be the best (and pos-
sibly only) potential bald eagle nesting habitat
along Deadman Creek.
Watana Damsite to Devil Canyon Damsite
-Habitat Loss
Some nesting habitat for ground-nesting raptors
(e.g., merl ins, northern harriers, short-eared
owls} and tree-nesting raptors (e.g., merlins,
goshawks, sharp-shinned hawks and owls) may occur
along the Watana-Devil Canyon section of the access
road and may be lost; however, no known cliff-
nesting habitat will be lost.
-Disturbance
Two nesting locations, one golden eagle (GE-18) and
one raven (R-21), may be susceptible to disturbance
from the Watana-Dev il Canyon section of the access
road. Both are near the western end of the road,
within about 0.2-0.3 miles (0.4 km) of the center-
line (see Table E.3.160}. Furthermore, a bridge
will be built across the river about 0.5 miles
(0.8 km) downstream from the golden eagle location;
E-3-489
4.3 -Impacts -Access
the activity during construction may result in
temporary abanonment of this site (see Section
4.4.3[a]).
(iii) Devil Canyon Damsite to Gold Creek
-Habitat Loss
Some nesting habitat for ground and tree-nesting
raptors may occur along the proposed railroad
access route from Devil Canyon to Gold Creek; how-
ever, no known nesting locations will be lost. No
known cliff-nesting locations occur in this section
of the access road.
-Disturbance
The proposed railroad link between Devil Canyon and
Gold Creek will pass about 0.3 mile (0.5 km)
southeast across the river from one bald eagle
location (BE-8, see Table E.3.160). Considerable
disturbance may result from construction activities
(Table £3.160) (see Section 4.4.3[a]).
(j) Waterbirds and Other Birds
Impacts of access roads on birds wil 1 result from habitat
loss and alteration, disturbance from traffic and people
associated with the project, direct mortality from both
collisions with vehicles and increased hunting pressure, and
indirect effects on nesting success because of increased
recreational use. The most significant of these impacts
vary with species group (Table £.3.166), but for most
species, none will be as serious as the impacts resulting
from the flooding of the impoundments.
A crude estimate of 2000 breeding birds will be lost
because of habitat loss from construction of the access road
(Table E.3.166). Largest numerical losses will occur in the
following species: tree sparrow (550), savannah sparrow
(416), Wilson's warbler (356), and white-crowned sparrow
(156).
Habitat alteration wi 11 include some opening of the canopy
where the road passes through closed forest and shrubl and.
This may result in a change in species composition of breed-
ing birds. In at least one instance (Jeglum 1975), building
of a road that blocked drainage through a portion of the
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4.3 -Impacts -Access
boreal forest has been shown to improve habitat for some
waterbirds.
Effects of disturbances from road traffic will probably be
minor for most species, but there are few quantitative data
to support this argument. In one of the few quantitative
studies of disturbance to songbirds, Ferris (1979) reported
no differences in breeding bird densities adjacent and
distant from 4-lane and 2-lane highways in Maine. He did
find a small difference in species composition that was
ascribed to edge effects adjacent to the highway.
Some species of low open habitats may be more affected. Van
der Zande et al. (1980) found that two and possibly three of
the four shorebird species they studied nested at 1 ower
densities up to at least 0.67 mile (1 km) from both busy and
relatively quiet roads. In some cases, nesting density was
reduced by 60 percent. Quantitative studies of species
nesting in open habitats in Alaska are not available, but
similar effects caul d occur with ptarmigan, some shorebird
species, and some passer·ine species.
Some birds will undoubtedly be killed by road traffic.
Species such as spruce grouse will be attracted to the road
as a source of gravel (Carbyn 1968), whereas scavengers,
including ravens and possibly eagles, will be attracted by
road-killed wildlife. However, mortality from collisions
will probably have a lesser effect on gamebirds than will
increased hunting pressure. The middle Susitna Basin is
relatively inaccessible at present, and it is likely that
little game bird hunting occurs there. When road access is
provided, hunting will undoubtedly increase and will prob-
ably be concentrated along the road. Weeden (1972) found
that hunters killed a much larger proportion of ptarmigan
within 2624 feet (800 m) of the Steese Highway than farther
away. The same would likely be true for other game birds •
Increased recreational use or human disturbance in wilder-
ness areas in other parts of North America has been associa-
ted with various behavioral effects, and in some cases with
reduced nesting success. Loons and grebes appear to be
particularly affected by boating activity. Nesting success
in both groups has been shown to decrease with increasing
presence of boats and canoes {Ream 1976, Euler 1978,
Mcintyre 1978). Power boats may also destroy 1 oon nests
through wave action {Vermeer 1973).
Recreational activities, particularly in open habitats, may
result in nest destruction by predators after incubating
E-3-491
4.3 -Impacts -Transmission Lines
adults,are flushed. This has been documented for at least
two duck species and the Canada goose (Hammond and Forward
1956, Macinnes and Misra 1972}. Presumably, similar nest
1 asses caul d occur in upland tundra species flushed from
their nests by all-terrain vehicles or other recreational
activities.
(k} Non-Game (Small) Mammals
The proposed access roads to the Susitna dams will traverse
a wide variety of small mammal habitats, but will mostly be
in shrubland and tundra (Table E.3.84}. Although all
species of small mammals are expected to be affected to some
extent, only the species most affected (those living in
shrubland and tundra habitats) will be discussed below.
Impacts include increased mortality, impeded dispersal,
presence of new habitats, and changes in drainage patterns.
In areas of moist tundra, the gravel berm that will consti-
tute the roadbed will act as a barrier to dispersal of small
mammals. Traffic on the road will cause increased mortality
in local populations. However, no serious changes in re-
gional population sizes or structures are expected.
The well-drained gravel of the roadbed will provide ideal
burrow sites for arctic ground squirrels and singing voles.
The revegetated areas on the edges of the gravel berm may
also be colonized by meadow or singing voles and some
species of shrews.
Portions of the road will likely cause subtle changes in
drainage patterns in lateral areas which in turn may result
in alterations to vegetation. The types of vegetation that
become established will depend on whether water levels in-
crease or decrease as a result of the road. Species compo-
sition of small mammals in these areas will shift according-
ly, with brown lemmings, bog lemmings, and tundra voles
preferring the wetter areas; and red-backed voles, singing
voles, and shrews attracted to the well-drained areas.
4.3.4 -Transmission Lines
The construction and operation of the transmission lines associa-
ted with the project will impact a wide variety of wildlife. The
four segments of transmission lines--Cook Inlet-to-Willow, Healy-
to-Fairbanks, Wi 11 ow-to-Healy (the In terti e), and Watana-to-the
Intertie--extend over 350 miles (563 km}, traversing habitats
ranging from closed forests to tundra (see Table E.3.86. Several
types of impacts can be expected, including habitat
E-3-492
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4.3 -Impacts -Access
alterations, disturbance during construction, direct impacts
caused by the presence of the transmission lines, and indirect
impacts resulting from improved access (see Section 4.3.3).
The cleared width of the corridor will be 300 feet (91.4 m) for 2
towers, 400 feet (121.9 m} for 3 towers, and 510 feet (155.4 m)
for 4 towers (Figure E.3.85). Between Watana and the intertie, a
2-tower corridor will be cleared. With the addition of Devil
Canyon power, a 2-tower corridor will be cleared from the Dev·ll
Canyon powerho.use to the Watana-Intertie line and the existing 2
tower corridor from that junction to the intertie (12.9 km) will
be widened to 4 towers. From the junction with the intertie
north to Healy, the intertie will be widened from 1 to 2 towers.
From Healy, a new tower corridor, paralleling the old corridor,
will be cleared to the Ester substation near Fairbanks. From the
junction .with the intertie south to Anchorage, the existing
corridor wi 11 be widened from 1 to 3 towers. A map of the
transmission corridor route appears on Figure E.3.37. Initial
clearing wi 11 be done with a hydro-ax or other mechanical equip-
ment. Vegetation will be cut to 6 inches for most of the corri-
dor, as described in Section 3.4.2 and 3.4.3 (Figure E.3.85).
Clipped vegetation will be stockpiled, then hauled to another
site for burning or disposal. The vegetation will be maintained
periodically by repeating these measures.
In general, the transmission corridor will impact local wildlife
through disturbance during clearing, which will occur periodical-
ly throughout the 1 ife of the project and through habitat al tera-
tion. Disturbance is most likely to have a serious impact on
nesting birds, particularly raptors near the corridor and
raptors, small mammals, small terrestrial birds, and waterfowl
which may suffer nest destruction within the cleared areas.
Larger mammals which are sensitive to disturbance may avoid the
corridor during clearing operations in areas where it overlaps
their range (see sections below) but are unlikely to suffer any
serious impacts. Moose calving concentrations and bear den
sites, if they occur in the corridor, would be the most sensitive
areas. Vegetation within the corridor will be maintained at
early successional stages by periodic clipping. Areas of various
vegetation types which will be altered by transmission corridor
clearing appear in Tables E.3.35 through E.3.36. This will cause
local alterations in home ranges of small species which are rest-
ricted to closed forests where they overlap the corridor. Large
bodied, more mobile species, will be less affected. Many species
will benefit from the vegetation diversity which the corridor
will provide. Small mammals {particularly voles) are likely to
colonize the corridor and will provide an easily accessible prey
for some raptor species. Small birds which will colonize the
E-3-493
4.3 -Impacts -Transmission Lines
corridor will also provide accessible prey for raptors. Moose
and black bear will also experience positive impacts.
(a) Big Game
(i) Cook Inlet to Willow
The southernmost segment of the transmission corri-
dor, from Cook Inlet to Willow, traverses mostly
forest vegetation types (Table E.3.86). The most
common community types are closed and open mixed
forest and closed birch forest. The big game species
that are most likely to be affected by the clearing
of these forest types are moose and black bears.
Both of these species utilize browse in early-to-mid-
successional stands, and would likely benefit from
the vegetative communities present in the trans-
mission corridor after clearing (Scotter 1971,
Lindzey and Meslow 1977). There are little data
quantifying the effects of such clearings in terms of
population productivity, but the general conclusion
is that transmission line clearing should increase
carrying capacity for moose and black bears (Sopuck
et al. 1979).
The disturbances caused by human activities during
construction will be temporary effects. Most big
game animals will relocate during the construction
phase, but are expected to return once construct ion
is completed (Commonwealth 1982). Serious impacts
are expected only if clearing and construction occur
near moose calving grounds or bear denning sites.
Disturbance of animals at such sites could cause
decreases in productivity. The increase in human
activity in the area between Willow-Cook Inlet during
the construction of the transmission line is unlikely
to affect regional distribution of big game species.
This area is already subject to high levels of human
activity. The most abundant big game species--moose
and black bear--are fairly tolerant of human distur-
bance; those species easily disturbed (i.e., wolf,
wolverine, brown bear) are already rare in the area.
{ii) Healy to Fairbanks
The transmission line right-of-way in this area will
traverse mostly open spruce forests, along with mixed
low shrub, open mixed forest, and open deciduous
forest (Table E.3.86). In all cases, community types
E-3-494
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4.3 -Impacts -Transmission Lines
that will be affected by clearing operations are
widespread and abundant in the area.
Impacts are expected to be similar to those discussed
in the Cook Inlet to Willow section above. Most of
the direct impacts will occur during the construction
period, when disturbance will cause big game species
to relocate. After construction, moose and bears are
expected to benefit from the early successional com-
munities along the corridor. The other big game
species are uncommon in this area.
(iii) Willow to Healy
(iv)
The transmission corridor from Willow to Healy (the
intertie) will have to be widened to accommodate the
power from the Susitna project. Most of the intertie
is located in forest types: bottomland, lowland, and
upland spruce-hardwood forests (Commonwealth 1982).
The additional clearing required will affect local
populations of moose, caribou, Dall sheep, brown
bears, and black bears. Animals that relocate
because of disturbance from construction activities
can be expectedto return.
Most of the major impacts associated with trans-
mission corridors (discussed in the preceding
sections) will already be effective because of the
existence of the intertie. Thus, the modification
required for the Susitna project is not expected to
increase access, hunting, or long-term human distur-
bance levels.
Watana Dam to the Intertie
The transmission corridor from Watana dam to the
intertie traverses mixed spruce-hardwood forests and
brush communities, paralleling the road and railroad
access routes (Table E.3.85). Clearing required in
forested areas will probably have a beneficial effect
on black bear and moose.
(b) Furbearers
Furbearers will be affected by construction of transmission
lines caused by habitat alteration and increased trapping
pressure resulting from improved access. Although it has
been shown that clear-cut areas are not a barrier to travel
E-3-495 I
4.3 -Impacts -Transmission Lines
by short-tailed weasel, least weasel, mink, marten, or other
mustelids, cleared areas are usually not used for hunting
(Soutiere 1978), and some furbearers may avoid disturbed
areas. Forested areas offer better sub-nivian hunting con-
ditions because the bases of trees, logs, and windfalls
provide numerous entry points (Koehler et al. 1975).
Forested habitat supporting approximately 6 marten (see
winter model, Section 4.3.1 [m]) will be cleared for the
transmission corridor.
Foxes and coyotes are sometimes attracted to cleared areas
as movement corridors (Penner 1976). Both foxes and coyotes
may benefit from the removal of forest vegetation, since
they feed heavily on microtine rodents.
Transmission lines will increase access for trappers and
could result in local population reductions of some furbear-
ers, particularly in presently remote areas. Marten and
beaver will probably suffer the greatest impact, since they
are currently the target of most trapper effort.
The impact of trapping on coyote, red fox, and lynx will
probably be less severe, since they are wider ranging than
the smaller mustelids. Least weasels, short-tailed weasels,
and mink have historically received little trapping pres-
sure.
(c) Birds
The construction and operation of the transmission corridors
wi 11 affect birds mostly as a result of changes in vegeta-
tion height, disturbance during initial construction and
maintenance, and the electrocution or collision mortality of
large raptors and swans from transmission wires. Since much
of the transmission corridor passes through forest, forest
species will be replaced by birds of shrub and open habitat.
Species diversity may also change (see Section 4.3.1 [p][i]
-Habitat Alteration.
Currently, there are no transmission lines in the vicinity
of the project (the nearest comparable lines occur between
Anchorage and Willow, and between Healy and Fairbanks).
Although no studies have been conducted and no data are
currently available regarding incidents of bird collisions
or electrocutions with these transmission lines, shorebirds
have collided with various kinds of guy wires in western
coast a 1 A 1 ask a during foggy weather (Gibson 1982 persona 1
communication), and collisions of birds (especially water-
fowl) with overhead ground wires have been documented
E-3-496
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4.3 -Impacts -Transmission Lines
elsewhere in North America (James and Haak 1979). Among
waterfowl, swans are particularly susceptible to collisions
with power lines (Avery et al 1980). In general, bird
collisions with transmission lines are difficult to prevent
(marking lines may minimize collisons to some extent), but
also tend to be biologically insignificant (James and Haak
1979).
Birds of prey are susceptible to electrocution as a result
of perching on the structures (Harrison 1963). Electrocu-
tion is the greatest potential impact of power lines on both
raptors and ravens. However, the selected transmission
tower and line configuration is such that little possibility
for bird electrocution exists. However, the possibility of
electrocution still exists along the single 34 kv construc-
tion transmission line to be built from Cantwell to Watana
via the Denali Highway. Larger size is the greatest factor
affecting species vulnerability to electrocution (Oldendorff
et al. 1981). Consequently, golden and bald eagles are the
most susceptible of the raptors inhabiting the area being
considered. In addition, immature or subadult eagles are
more susceptible to electrocution than adults. Buteos
(e.g., red-tailed hawk and rough-legged hawk) are also
vulnerable, but accipiters (e.g., goshawk and sharp-skinned
hawks) and even the larger falcons (e.g., peregrines and
gyrfalcons) are rarely electrocuted (01 endorff et al.
1981).
Only one known raptor nest occurs near the proposed trans-
mission route, but this nest is of special concern because
it was once occupied by peregrine fa 1 cons, an endangered
species. The nest occurs along the Tanana River on the east
side of the corridor between Healy and Fairbanks. This nest
was first discovered in the early 1960s, but was inactive in
the early 1970s (Roseneau 1982 personal communication). It
was checked by the U.S. Fish and Wildlife Service in 1982
and was also inactive that year (Amaral 1982 personal
communication). Whether or not it will be used again is
unknown. If the nest is active during the construction of
the 1 i ne, the bi r..ds may abandon it as a result of the
disturbance. If the nest remains inactive during line
construction, however, it will most likely be acceptable for
1 ater use during the ope rat i ona 1 phase of the the 1 i ne. If
necessary, the transmission line in this area could be
constructed during a time period that would reduce the like-
lihood of disturbing nesting peregrines. Furthermore, a
Section 7 consultation, as required by the Endangered
Species Act, will be conducted with the U.S. Fish and
Wildlife Service to help insure that the peregrine nest is
not affected.
E-3-497
4.3 Impacts Tr ansmi ssi on Li nes
Potential disturbance to bald eagles as a result of
construction and maintenance of the i nterti e line between
Willow and the Gold Creek Switching Station will probably be
minimal because the majority of the known nesting locations
and nesting habitat occur along the banks and on the islands
of the Susitna River (Table E.3.129). However, at least
three nesting locations occur 1 mile (1.6 km) or less from
the corridor, and veri fi cations of more accurate distances
will be made to identify locales where mitigation may be
necessary. Although no nests of bald eagles are known to
occur in the immediate vicinity of the corridor centerline,
some potential bald eagle nesting habitat may be lost as a
result of clearing balsam poplar and white spruce trees in
some sections of the proposed line.
Potential disturbance will be mini mal to golden eagles and
gyrfalcons as a result of construction and maintenance of
the intertie line between the Gold Creek Switching Station
and Healy. No known nesting locations or nesting cliffs
occur in the valley bottom along the proposed route. All
known nests and nesting habitat are at elevations well above
the valley floor. Although no nests of bald eagles are
known to occur along the route north of the mouth of
Indian River, some nesting habitat may be lost as a result
of clearing poplar trees in some areas between Chulitna,
Butte, and Hurricane.
Minimal disturbance of raptors and ravens in the study area
is anticipated as a result of construction of the hi qh vol-
tage transmission lines between the Watana dam and the
i nterti e. Only one golden eagle and two raven nesting loca-
tions may be susceptible (GE-18, R-13, and R-21; see Table
E .3.160). Potential for disturbance as a result of summer
construction would be greatest at GE-18 and R-21 if these
nesting locations were active in the year when construction
occurred. However, this potential impact, although addi-
tive, is considered far less severe than the longer term
potential impacts associated with nearby dam construction
upriver and bridge construction and associated traffic down-
river from GE-18 and R-21.
Table E.3.71.5 indicates an order-of-magnitude of 655 of
1,200 small to medium-sized breeding birds lost to the
transmission line, less than 0.1 percent of the population
within 16 km of the Susitna ~ ver between the Mclaren ~ver
and Gold Creek.
£-3-498
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4.3 -Impacts -Summary
(d) Non-game {small) Mammals
The transmission lines for the Susitna project will traverse
a wide variety of small mammal habitats. These transmission
corridors will be cleared of trees and tall shrubs. Because
most small mammals are ecotone species, they are expected to
benefit from the edge effects created by the clearings. One
example is the snowshoe hare, which relies on dense black
spruce forests for cover, but prefers more open areas for
forage (Kessel et al. 1982a). Overall, transmission
corridors are not expected to adversely impact sma 11
mammals.
4.3.5 -Impact Summary
This section summarizes those impacts on wildlife populations
predicted to be of sufficient magnitude to influence mitigation
planning. The emphasis is concentrated on what are considered to
be the most serious impacts to wildlife population levels; both
positive and negative impacts are discussed.
Whether impacts to wildlife are judged to be positive or negative
depends on the perspective of judgment. For example, increased
access by hunters and trappers usually depresses population
levels of big game species and furbearers. But at the same time,
increased access has the potential to increase the 1 ong-term
yield and value of this wildlife to consumptive users.
Herein we address impacts only from the perspective of the wild-
life populations per se. An increase in wildlife abundance or
production is a positive impact; a decrease in wildlife abundance
or production is a negative impact. Project actions known or
specula ted to cause measurable changes in project area wi 1 dl i fe
population or production levels are discussed, but those actions
thought to cause negligible or no changes are not.
(a) Big Game
The big game populations expected to be affected by the
Susltna project are moose, black bear, brown bear, wolf,
wolverine, Dall sheep, and caribou. The main effect on
these species will be through habitat loss by ·inundation,
interference with movements, habitat alteration, distur-
bance, collision mortality, increased necessity for killing
nuisance animals, and increased access afforded to hunters.
Moose will be most severely affected by habitat loss caused
by inundation of spring and winter range. In winters of
relatively light snowfall (i.e., less than 30 inches),
approximately 300 moose occur in the impoundment zones. A
preliminary estimate of winter carrying capacity for the
E-3-499
4.3 -Impacts -Summary
Watana impoundment zone is 301 resident moose (see Appendix
3.H). However, when snow depths exceed 30 inches, much
higher numbers of moose are expected to move to the impound-
ment zones (ADF&G 1982a). The effects of habitat loss on
moose are being addressed through continuing studies and
through the development of a habitat-based model of carrying
capacity.
Moose displaced from the impoundment zones will compete for
food and space with other moose. The consequences of this
competition could seriously reduce the carrying capacity of
adjacent range with potential long-term effects on mortal-
ity rates, predator populations, and natality. The computer
model being developed wi 11 be used to determine whether
adjacent areas can support these additional moose (see
Section 4.3.1[a][iii] and Section 4.4.2[b] Mitigation Plan
6. Borrow sites, camps, and the airstrip at Watana will
remove winter habitat for about 37 moose. These areas will
revegetate after construction, but plant growth where top-
soi 1 has been removed wi 11 be very slow. Transmission
corridors contain browse supplies that will support 47 moose
for 180 winter days. The growth of vegetation between years
of vegetation maintenance (clearing) will compensate for the
loss just after clearing.
The reduced summer flows and increased winter flows will
alter the distribution of floodplain communities downstream
from Devil Canyon. When Watana only is operating, the width
of the unvegetated floodplain between Devil Canyon and
Talkeetna will increase, but with both dams, some of the
fl oodp 1 a in will be reco 1 on i zed by vegetation. The open
water in winter from Devil Canyon to Talkeetna (both dams)
will make much of this vegetation unavailable because moose
will not cross the open water to islands and heavy frosting
will cover vegetation near the river. Changes downstream
from Talkeetna cannot be predicted because vegetation
patterns wi 11 be influenced by snow depths each winter, by
the speed of spring breakup, by flow releases as they are
affected by power demand, and by river morphology along the
various reaches. Because large numbers of moose (over 1000
in 1982) move to the lower river floodplain, small changes
in vegetation patterns could have an adverse affect.
Disturbance and altered movement patterns are unlikely to
have detectable population-level effects. Some calving
areas (on islands downstream from the project area to
Talkeetna) may become unava i 1 ab 1 e because of open water.
However, moose are capable of altering habitual movement
patterns to adapt to such changes in range, and no long-term
E-3-500
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4.3 -Impacts -Summary
population-level effects are anticipated to result from
construction-related disturbances or altered movements.
The consequences of increased moose mortality caused by
impoundment hazards, collisions with trains and vehicles,
and increased predation levels are being explored through
the use of computer modeling. These factors a 1 one are
likely to have a much lesser effect on moose than will
habitat. loss. However, their cumulative effects with
habitat loss and reduction in carrying capacity of adjacent
range may be severe.
The Nelchina caribou herd will be most affected by interfer-
ence with movements across the impoundment zone and access
.road. At the current herd size, no population-level effect
is likely to be detected during the construction period. but
the access road may block the movements of 90 percent or
more of those caribou which may attempt to cross, thus
isolating the mountains north of the river and west of the
road from the remainder of the herd's range. As the herd
increases, the importance of this historically used range
will increase and the loss of areas to the west of the road
may decrease the carrying capacity of the range by up to 10
percent. Caribou cows with calves may avoid the road, but
no direct effect on productivity or survival of calves is
expected.
The Devil Canyon impoundment and transmission 1 i nes wi 11
have little effect on caribou. The Watana impoundment, how-
ever, will alter caribou movements and may result in cross-
ing mortalities because of hazardous ice conditions or
floating debris. The potential for increased mortality can-
not be predicted, since ice conditions will vary each year
and the number of car·i bou crossing the impoundment as the
herd expands is unknown.
Increased recreational use of the area may become a severe
impact. The calving area and summer range of females with
calves would be most sensitive. Heavy use of widespread
areas by all-terrain vehicles would also seriously reduce
carrying capacity through vegetation damage. Although no
quantification is possible, the cumulative effects of
intense and unpredi cable recreati anal disturbance on the
historically used calving ground and the potential loss of
some portions of the range due to blocked access in concert
with increased mortality during migration across the Watana
impoundment may constitute a severe impact.
E-3-501
4.3 -Impacts -Summary
The ADF&G has expressed concern that impacts with no
measureable effect on current population levels may nonthe-
less further reduce the ratio of harvest to demand, which is
already low, by eliminating the option to allow a substan-
tial increase in herd size for that reason.
Dall sheep will be affected primarily by partial inundation
and disturbance at the Jay Creek mineral 1 i ck. Oi sturbance
anticipated is mostly recreational, both during and after
the construction phase, and from low-flying aircraft. The
consequences of sheep abandoning the Jay Creek 1 i ck are
unclear. Several other licks occur within the range of the
Watana Hills population, but because sheep show high fideli-
ty to particular areas, it is not known if these licks would
replace Jay Creek.
Brown bears will lose important spring feeding areas to the
impoundment zones and will also be adversely affected by
1 ower numbers of moose. Sows with cubs do not use the
impoundment zones but about half of the remaining radio-
collared bears moved there in spring during recent studies.
During the construction phase, a number of bears may be
killed for safety reasons or may die after being disturbed
from winter dens by people on the ground or in 1 ow-flying
aircraft. In addition, bear/human conflicts have a great
potential to cause significant loss of work time for con-
tractors, injuries to employees, and property damage. No
denning areas will be flooded by the impoundments.
The reservoir may alter the movements of brown bears between
seasonally important food sources, particularly when float-
ing ice or debris are present. Because the relationship
between brown bear foods and population levels is poorly
understood, the impact of the project on brown bear carrying
capacity cannot be predicted. The effect of reductions in
salmon spawning between Portage Creek and Talkeetna similar-
ly cannot be predicted.
Management strategies and priorities beyond the control of
the Power Authority will determine to what extent hunting
and poaching become severe mortality sources. Historically,
brown bear have been ·sacrificed to the benefit of ungulate
species more desirable to subsistence users by management
guidelines.
Black bears will be severely affected by the project,
primarily as a result of inundation of denni ng and feeding
habitat upstream from Tsusena Creek. The Watana reservoir
E-3-502
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4. 3 -Impacts -Summary
will inundate approximately 69 percent of the denning habi-
tat occurring in that area (black bears are restricted to
the band of forest along the river), whereas about 6 percent
of the denning habitat in the Devil Canyon reservoir vicini-
ty will be lost. Additional denning areas will be impacted
by road and .transmission line construction. The resident
population of about 30-50 bears between the Tyone River and
Tsusena Creek will probably be eliminated. Bears residing
downstream from Tsusena Creek may also be affected by pro-
ject facilities near Watana interfering with movements up-
stream in summer. As discussed for brown bear, the effects
of possibly reduced salmon runs downstream from Portage
Creek and disturbance from recreational users during salmon
runs on the black bear population cannot be quantified.
Cumulative impacts of mort a 1 ity from hunting increased
encounters with brown bears and bear/human conflicts in
concert with loss of denning and feeding habitats due to
facilities and disturbance will greatly reduce the black
bear population in the middle basin.
Wolf populations are currently controlled by human harvest
levels (much of it illegal), and the reduction in moose
numbers will not be a major factor under these conditions.
Improved access in the project area may result in even
heavier exploitation of wolves. If wolf survival greatly
increases because of better enforcement and management, the
lower prey base may affect as many as 10 wolf packs in the
project area. The Watana pack will be seriously reduced and
possibly eliminated due to loss of hunting areas and reduced
moose populations. Immediately following filling of the
Watana reservoir displaced moose wi 11 be more vul nerab 1 e to
predation. Impoundment hazards and the advantages conferred
on predators along the impoundment shoreline will also act
to increase the availability of prey. However, the long-
term effects of the impoundment are more likely to result in
a reduced availability of prey for the Watana pack. Winter
availability of caribou to individual wolf packs varies year
to year. However, no net decrease in availability of cari-
bou to the wo 1 ves of the middle basin is anticipated. The
above discussion of caribou trials the elimination of a
management option for substantially increasing herd size to
allow greater satisfaction for subsistence users. Although
this also eliminates the option of substantially greater
wolf populations, those management goals would conflict with
this eventuality anyway. The extent to which increased
access and use of the middle basin reduces wolf populations
depends almost entirely on management priorities of the
Alaska Department of Fish and Game and is beyond the control
of the Alaska Power Authority. Because wolves are uncommon
E-3-503
4. 3 -Impacts -Summary
downstream from Devil Canyon, changes in moose numbers there
are unlikely to have any effects.
Wolverine wi 11 be affected primarily by improved access for
trappers. Habitat supporting about two wolverine will be
lost to the project. Additional temporary loss of habitat
due to both construction related and recreational distur-
bance is possible but likely to affect only small areas of
the territories of a few individuals. Higher turnover rates
hypothesized for moose populations would result in increased
availability of carrion. Overall, changes in wolverine
populations will be difficult to detect due to naturally low
density and dispersal from surrounding productive habitat.
Bel ukha whales wi 11 not be measurably affected by the pro-
ject at any time of the year.
(b) Furbearers
Overall, beavers are expected to benefit from the project
because of regulated flows in downstream reaches, but local
populations will be adversely affected during road and dam
construction, and many will be vulnerable to increased trap-
ping because of improved access. Approximately 40 beavers
now occupy sections of Deadman Creek designated as borrow
sites for road construction. No beavers reside in the
impoundment areas, but the lakes in and adjacent to Borrow
Site K at Devi 1 Canyon support approximately 10 beavers.
There are approximately 25 beavers along Jack Long Creek;
these beavers could be adversely affected by increased silt-
ation or clearing of riparian vegetation during construction
of the railroad and staging area. In total, about 75
beavers will be lost to the project during its construction.
It is not known if improved habitat downstream wi 11 compen-
sate for this loss without enhancement.
Habitat improvements anticipated for beaver in downstream
reaches include: an increase in availability of suitable
overwintering sites caused by increased flow (i.e., deeper
water preventing freeze out), greater stability in anchoring
food caches due to stabi 1 i zed flows, and ava i 1 abi 1 i lty of
shallower sites than are currently used for overwintering
because of open water. A beaver habitat model is being
developed to assist in impact assessment and mitigation
planning. This model incorporates data on river flows,
water temperatures, depth of water under the ice,
vegetation, bank substrates, and beaver populations with
various flow releases and trapper effort.
E-3-504
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4.3 -Impacts -Summary
The project will have an insignificant effect on muskrat,
except that improved access may result in overtrappi ng of
some areas. No muskrat occur in 1 akes to be used as borrow
sites or other facilities, but 5 lakes within the impound-
ment zone (on lower Watana Creek) are occupied by muskrats.
Approximately 5-10 muskrats will be lost because of impound-
ment fi 11 i ng and construction. Improved habitat for beaver
downstream from the dams will also have a beneficial effect
on muskrat, and should easily compensate for the minor loss
of habitat within the impoundment.
Mink and otter will be adversely affected by clearing and
inundation of the impoundment areas, removal of road-build-
ing materials from Deadman Creek and wetland areas, and by
increased trapping pressure. Both mink and otter are some-
what sensitive to disturbance and may suffer significantly
from increased presence of fishermen and recreation a 1 users
in remaining rtver habitat. Assuming that all habitat along
the mainstem upstream from Gold Creek and its tributaries
supports equal densities of mink and otter, about 21 percent
of the river and stream habitat of these species wi 11 be
lost. Few impacts on lakes and ponds will occur. Regulated
flows are expected to improve downstream habitat for these
species, and the stable water level on the Devil Canyon
reservoir during most of the year will probably allow these
species to reside there.
All upland furbearer populations are expected to decline for
two rna in reasons--i nun dati on of portions of their habitats
by impoundments, and increased trapping pressure caused by
easier trapper access.
Coyotes are uncommon upstream from Devi 1 Canyon and are
likely to remain so; the impact on this species will be
negligible throughout the project area. Increases in
numbers of coyotes would be anticipated only if wolves are
severely reduced or eliminated. Red foxes will be adversely
affected by loss of habitat in the impoundment area,
habituation to human activity along the roads and at camps
and l andfi 11 s, and by increased trapping pressure. The
access roads occur within 0.5 mile of several large red fox
denning complexes, and local overharvesting of foxes may
occur. Because foxes den and feed primarily at elevations
above the impoundment level, major population effects due to
habitat loss are not anticipated. Direct mortality caused
by trapping and the killing of nuisance animals is likely to
have a significant population level effect.
E-3-505
4. 3 -Impacts -Summary
Marten will be the most severely affected furbearer species.
Habitat supporting approximately 100 marten will be lost to
the Watana reservoir; the Devi 1 Canyon reservoir contains
habitat supporting about 21 marten; and forested areas
supporting about 6 marten will be cleared for transmission
corridors. In total, habitat supporting approximately 130
marten will be lost to the project. Although improved
access may allow a higher trapping yield from the remaining
population, local overharvesting of marten in some areas may
occur. Major impacts on lynx, short-tailed weasel, and
least weasel are not expected.
(c) Birds and Non-game Mammals
Birds will be affected primarily by habitat loss to inunda-
tion and disturbance of nests. Sixty-three to sixty-eight
percent of the known raptor cliff-nesting locations in the
middle and upper basins and 70 percent of the known raptor
tree-nesting locations will be affected by the project.
This includes over half of the golden eagle nests, 75 per-
cent of the bald eagle nests, 33 percent of the gyrfalcon
nests, and 66 percent of the known goshawk nests (Tab 1 e
E.3.160). Raptors downstream from Gold Creek will not be
affected, except in a few cases where construction of trans-
mission lines disturbs raptors at their nests. Small
numbers of raptors may be lost as a result of electrocution
along power lines.
Waterbirds of 1 acustri ne habitats wi 11 suffer only minor
impacts, since only 38 ha of lakes and ponds will be flood-
ed. Trumpeter swans which nest o.n lakes near the project
area may be adversely affected by low-flying aircraft. Most
swan nests are some distance to the east of project facili-
ties and no disturbance is anticipated. Birds of fluviatile
habitats will suffer a significant loss of habitat. Breed-
; ng habitat for spotted sandpiper, mew gull, harlequin
duck, common and red-breasted merganser, semipalinated
plover, wandering tattler, and arctic tern will be lost.
Additional 1 asses of breeding habitat in forests will occur
for goldeneyes and lesser yellowlegs. Sandbars, islands and
riparian shoreline areas used for feeding, roosting and
loafing by shorebirds will be flooded. River and stream
flooding habitat for breeding dippers, mergansers, harlequin
ducks and go 1 deneyes will be 1 ost. A 1 though the middle
basin is not a migration corridor, the open water areas
within the impoundments will be used for leafing by early
migrants before other waterbodi es are open. The drawdown
zones will be used as 1 oafi ng habitat for migrant
shorebirds, but food availability will be low. The
E-3-506
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4.3 -Impacts -Summary
impoundments are likely to offer very few food resources to
migrants or residents, although low densities of fish and
invertebrate prey wi 11 be present. Open-water areas down-
stream from the dams may benefit migrant waterfowl and
shorebirds and provide winter habitat for the dipper.
A 1 though the 1 arge impoundments wi 11 greatly increase in
surface area of water in the middle basin, the drawdown of
the Watana reservoir will minimize its importance as lacus-
trine habitat. The Devil Canyon impoundment will be more
appropriate lake habitat, although recreational boating will
limit its use for shoreline nesters.
Populations of small and medium sized birds within 16 km of
the Susitna River between the Mclaren River and Gold Creek
will be reduced by 5 to 17 percent for most species and the
total number of breeding terestrial birds lost will approach
103,000. Proportionate losses are greatest for birds
restricted to forest habitats, and over 12 percent of the
populations within 16 km of the river of the following
species will be lost: spruce grouse 16 percent), hairy
woodpecker 16 percent), northern three-toed woodpecker 12
percent , brown cree er 16 percent , varied thrust 12
ercent , Swainson s Thrush 12 percent , yellow-rumped
warbler 13 ercent , and northern waterthrush 16 percent •
Largest numerical losses will be for species which are found
at high densities in a range of vegetation types: yellow-
rumped warbler 13,020, tree sparrow 10,112), dark-eyed
junco 7,990 , Swainson•s Huush 7,062 , Wilson•s warbler
6,760 , savannah sparrow 6,150 , fox sparrow 61 060 , and
white-crowned s arrow 5,992 • Habitat alteration will
affect the distribution and abundance of species, again with
birds restricted to closed forest habitats suffering losses,
while species associated with edge disturbed, or artificial
habitats wi 11 benefit. The increase in amount of edge may
increase species diversity and density in localized areas.
Bank and cliff swallows and kingfishers will experience
increases in availability of nesting habitats. Ravens and
gulls are likely to increase in numbers in the basin, parti-
cularly if refuse dumps are not adequately maintained.
Only those species of small mammals which are restricted to
forest habitats are -expected to experience a decrease in
regional abundance. Porcupines, snowshoe hares, pygmy
shrews and red squirrels wi 11 be most affected. Although
they are found in nearly every vegetation type in the Watana
area, red-backed voles are most common in spruce and cotton-
wood forests and will suffer a decrease of up to 5 percent
in the basin population. Meadow voles may actually increase
in the basin due to the appearance of disturbed and
reregul ated areas. The major impact of the projects on
small mammals will be local alterations in the distribution
and abundance of species.
E-3-507
4.4-Mitigation Plan
This mitigation plan has been developed for impacts likely to have
population-level effects on important species in accordance with the
approach outlined in Sections 1.2 and 1.3. As discussed in those
sections, mitigative measures have been prioritized as follows: avoid-
ance, mini mi zati on, recti fi cation, reduction, and compensation. Avoid-
ance and mini mi zat ion of imp acts are best achieved by i ncorpor at i ng
environmental criteria into preconstructi on planning and design and by
modifying certain construction practices. In many cases, measures to
avoid, minimize, or rectify impacts to wildlife are identical to the
preferred measures for mitigating impacts to botanical resources. The
mitigation plan for botanical resources (Section 3.4.2) discussed modi-
fications to engineering des\gn and construction planning for environ-
mental reasons, such as changes in the alignment of access roads and
t ransmi ssi on corridors; avoidance of certain riparian areas for grave 1
extraction, consolidation, and resiting of certain project facilities;
and rehabilitation of temporary construction sites. Si nee bot ani cal
resources assume their greatest importance as wildlife habitat, the
wildlife and botanical resources mitigation plans complement each
other. Measures discussed in the botanical resources plan that also
apply to wildlife mitigation are repeated only in appropriate cases.
Field studies sponsored by the Power Authority are continuing to refine
and quantify the results from three years of baseline and impact re-
search. As additional information from these continuing studies be-
comes available, certain concepts contained in this mitigation plan
wi 11 be refined to specify the number, location, and design of mitiga-
tion features.
The impact summary (Section 4.3.5) describes the impacts and criteria
used to identify impacts requiring mitigation. Impact issues are
treated here in three categories: (1) impact mechanisms resulting in
reduction in carrying capacity; (2) impact mechanisms which increase
mortality, thereby altering population structure and the ability of
populations to recover from other secondary impacts or natural mortal-
ity phenomena; (3) disturbance. Impact issues def\ned in Section 4.3
as habitat loss, habitat alteration, and barriers to movement represent
effective habitat loss and are treated as mechanisms resulting in re-
duced carrying capacity. An analysis of mitigation options is pre-
sented for each species or group for each mechanism. Separate mitiga-
tion plans are then presented which may apply to an individual species
or group {Section 4.4.2). A cost analysis and schedule for mitigation
appear in Section 4.4.3, and Section 4.4.4 documents all agency recom-
mendations for mitigation.
4.4 -Mitigation Plan
4.4.1-Impact Issues and Option Analysis
The following discussion presents an analysis of mitigation
options for each impact. The options to be implemented are
E-3-508
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4.4 -Mi ti gati on Plan
detailed in Section 4.4.2, and an analysis of residual
impacts with the chosen mitigation plans appears in Section
4.4.3.
(a) Reduction in Carrying Capacity
( i ) Moose
Project impacts on upstream habitat will reduce
carrying capacity through inundation of spring and
winter range. Approximately 37,502 acres (15,177 ha)
of vegetated habitat will be permanently lost to fa-
ci li ties and impoundments for both projects. This
represents winter habitat for 302 moose based on
carrying capacity estimates presented in Table E.3.92
and Appendix 3. H. The winter carrying capacity of
the Watana permanent fac\ li ties is 266 moose; that
for Devi 1 Canyon is an addi ti anal 36. Addi ti anal
habitat alteration due to temporary facilities and
borrow sites (4532 acres [1875 ha]) wi 11 bring the
total affected area to 42,135 acres {17,052 ha) in
the immediate vic\nity of the impoundments. The
total carrying capacity of these areas is 340 moose.
The no-project option is the only means of avoiding
this impact.
The impoundment zones may be important as a source of
early spring foods and as calving areas, and also as
winter range for moose {ADF&G 1982a). Their loss
could be temporarily avoided by delaying clear·ing of
the impoundment areas. However, the impoundment
zones must be cleared to avoid producing large quan-
tities of timber debris on the reservoirs. Habitat
lo~.S;:~-a·~:.~~e of clearing could be minimized by: (1)
~tneduli ng/cleari ng as close to reservoi r, .. -f-H"li-rrg--~.~s
~le; (2) leaving relatively larg~"island~1·
of ri parJ.an.. .. V-e.g.etat.i.pn uncleared; and/or {3r-crear-
' i ng ()nly trees and tall shrubs, leaving the browse
! species preferred by moose .
. To reduce vehicle traffic and impacts to other areas,
it is preferable to burn the cleared vegetation in
place rather than to transport it to some other area.
In order to retain browse vegetation, the slash would
have to be burned in piles (rather than a broadcast
burn). The increased use of machinery required for
pi ling may offset the benefits of preferential clear-
; ng of trees and tall shrubs.
E-3-509
4.4-Mitigation Plan
Temporary facilities during construction will remove
approximately 4532 acres (1875 ha) of vegetated habi-
tat. Avoidance is possible only by the no-project
alternative. Ml nimi zati on is possible by using side-
borrow techniques for road construction, which will
reduce the number of borrow sites, and by depositing
spoi 1 in the future impoundment areas or in depleted
borrow sites. (This is discussed more fully in
Section 3.4.2.[a][i].) Further minimization is possi-
ble by consolidating facilities. Rectification is
possible through revegetation (Section 3.4.2[a][i]).
The village and impoundments will permanently remove
about 37,502 acres (15,177 ha) of vegetated habitat.
These facilities are essential to the project, and
thus, this loss can be avoided only by not building
the project. No measures to rectify or reduce this
impact are feasible, and therefore, only compensation
is feasible for mitigation.
Clearing of vegetation in the transmission corridor
wi 11 result in habitat alteration. This alteration
cannot be completely avoided because some clearing
i s necessary to permit construct\ on to minimize main-
tenance costs and to permit rapid restoratl on of
power in case of line breakage. Minimization could
be accomplished by aligning the corridor through tun-
dra types where possible and by designing the corri-
dor to leave as much shrub vegetation as possible.
Compensation for clearing could be provided by allow-
; ng shrubs and trees to grow between maintenance
clearing, which would maintain the corridor in early
seral stages preferred by moose.
Moose displaced from the impoundment zones during
construction and filling wi 11 compete for food and
space with moose in adjacent areas. This may result
in overbrowsing of areas adjacent to the impoundments
and subsequently affect additional moose outside the
impoundment areas. This impact would be avoided by
managing the moose population through a controlled
hunt of moose in excess of the carrying capacity.
It is unclear whether regulated flows will result in
a net increase or decrease in the amount of browse
available to moose in the Susitna floodplain down-
stream from the Devi 1 Canyon dam. However, because
the lower basin may support very high densities of
moose in some winters, a small decrease in browse
E-3-510
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4.4-Mitigation Plan
( i i )
availability could affect a ·large number of moose.
Additional impacts on browse availability and quality
wi 11 result from blockage of movements by open water
between Devi 1 Canyon and Talkeetna and possible
frosting of adjacent browse.
No measures are av ai 1 ab 1 e to avoid this impact. Min-
imization is possible through regulating river tem-
perature to maintain nearly normal ice conditions in
the lower reaches of the river. Rectification may be
pos~ble through controlled flow releases, river
training structures, and enhancement techniques.
Addi ti anal compensation wi 11 occur because of the
increased avai 1 ability of winter browse which wi 11
result from the construction and maintenance of the
transmission corridor. Much of the route is adjacent
to the river and wi 11 provide winter browse in areas
adjacent to those in which browse could be lost.
Caribou
The likelihood of a reduction in carrying capacity
caused by blockage of movements by the Watana im-
poundment is unknown and undeterminable at current
population levels. If such an effect were demon-
strated, compensation would be the only feasible mit-
; gati on alternative.
The physical presence of the access road and the
vehicle traffic and other human activities associated
with it wi 11 interfere with the movements of caribou,
particularly in the Denali Highway to Watana section.
Avoidance of the road or failure to cross it would
result in habitat loss and decreased carrying capac-
; ty of the project area for caribou.
This impact cannot be avoided except through the no-
project alternative. Minimization is poss'ible
through realignment to avoid the center of the calv-
ing ground and through design changes to minimize
physical and visual impacts (i.e., side-borrow con-
struction). Further mini mi zati on waul d be possi b 1 e
by regulating traffic on the road and by reducing
dust. No rectification is possible. Compensation
would be required if the access road is shown to af-
fect the size, productivity, or di stri buti on of the
Nelchina herd.
E-3-511
4. 4 -Mi t i gat i on P 1 an
(iii) Dall Sheep
Partial inundation of the Jay Creek mineral lick and
blockage of access to the lick may reduce carrying
capacity of the area for Dall sheep. Up to 42 per-
cent of the surface area of the Jay Creek mineral
lick will be ~nundated each year by the Watana im-
poundment. Only 22 percent wi 11 be under water dur-
ing May and June when sheep use of the lick is great-
est. It is not known whether water in the reservoir
will leach minerals from the lick soils and reduce
the value of the annually inundated portion to sheep.
However, the reserv~r may interfere with the move-
ments of sheep between the west and east side of the
creek.
No avoidance, minimization, rectification, or reduc-
tion is possible. Compensation may be provided by
exposing new mineral soi 1 at the lick site to replace
that possibly lost to leaching.
(i v) Brown Bears
Impoundment clearing is necessary to eliminate debris
on the impoundment surface. Th.e clearing of the im-
poundment zone and permanent f aci 1 i ty areas wi 11 re-
duce the carrying capacity of the project area for
bears by e 1 i mi nat i ng spring feeding areas and other
habitats. Loss caused by clearing could be minimized
(as described for moose above) by: (1) scheduling
clearing as close to reservoir filling as feasible,
and/or (2) leaving large "islands" of riparian vege-
tation unc 1 eared.
Temporary facilities increase loss of habitat, but no
avoidance is possible. Minimization is possible
through use of side-borrow techniques for road con-
struction which reduce the number of borrow sites and
by depositing spoi 1 in the future impoundment or in
depleted borrow sites. Further minimization is poss-
ible by consolidating facilities. Rectification is
possible throagh revegetation.
Permanent habitat loss can be avoided only through
the no-project alternative. No measures to minimize,
rectify, or reduce this impact are feasi b 1 e, and
therefore, compensation is the only mitigation alter-
native.
E-3-512
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4.4-Mitigation Plan
(v)
A reduction in salmon spawning between Port age Creek
and Talkeetna has been identified as a possible fac-
tor which would reduce carrying capacity for brown
bear. This impact will be avoided through mainten-
ance of downstream sloughs for salmon spawning (see
Section 2.4.4 [a]).
A reduction in ungulate prey is also hypothesized to
reduce carrying capacity for brown bear. Mitigation
measures proposed for ungulate populations wi 11
avoid, minimize, or compensate for this impact.
A possible secondary impact of the project on brown
bear is displacement from the Prairie Creek area, a
bear concentration area during salmon runs. Project
access roads may accelerate mineral and recreational
developments in this area, making conflicts with bear
use of this resource occur sooner than they would in
the absence of the project. This impact could be re-
duced through cooperative management of deve 1 opment
and access by the Power Authority and resource agen-
cies.
Black Bears
Impacts of impoundment clearing, temporary facili-
ties, permanent habitat loss, and reduced prey avail-
ability are similar to those for brown bear, treated
above. Residual impacts to be treated through com-
pensation are much greater for black bear than for
brown bear for both denning and feeding habitats (see
Section 4.3.1 and 4.3.2).
Clearing of vegetation in the transmission corridor
wi 11 also result in habitat loss. Some clearing is
necessary to facilitate construction and maintenance
and to permit rapid restoration of power in case of
line breakage. Mini mi zati on could be achieved by
a 1 i gni ng the corridor through tundra types where
possi b 1 e and by designing the corridor to 1 eave as
much vegetation as possible.
Additi anal habitat 1 oss wi 11 result from the access
corridor and interference of Watana faci li ties with
upstream movements (see Section 4.3.1). Disturbance
may also make some denning habitat unsuitable. No
avoidance is possible for these impacts. Alignment
of the road away from spruce forest habitats would
E-3-513
4.4-Mitigation Plan
m1n1m1ze habitat loss. No other minimization, recti-
fication, or reduction is possible. Compensation is
the only alternative mitigation.
(vi) Wolves
Loss of hunting areas wi 11 reduce carrying capacity
for wolves mostly through reduced prey av~ lability.
Mitigation measures proposed for ungulate populations
wi 11 avoid, minimize, or compensate for this impact.
(vii ) Wo 1 veri ne
Loss of winter foraging habitat will reduce carrying
capacity for wolverine through reduced availability
of prey. A detectable change in populations is un-
likely. Avoidance is not possible. Minimization
through consolidation of facilities, spoi 1 disposal
in the impoundment, and side-borrow techniques is
possible. Some compensation may occur through an an-
ticipated increase in availability of carrion due to
hazards created by the impoundment, access roads, and
other faci li ties.
(viii) Beavers and Muskrat
The impoundments, facilities, and access road wi 11
remove habitat for approximately 75 beaver and 5-10
muskrat. The impact cannot be avoided except through
the no-project alternative. Partial avoidance is
possible through realignment of the access road route
and design changes to reduce the area disturbed.
Additional loss may be avoided by using only borrow
sites D, E, I, J, and K and obtaining access road
material from small upland sites rather than from
De adman Creek. Some compensation wi 11 occur through
improved habitat downstream from the dams.
(ix) Mink and Otter
Riverine habitat wi 11 be inundated and some stream
habitat along Deadman Creek will be lost to the ac-
cess road. Partial avoidance is possible through re-
alignment of the road and design changes to reduce
the area disturbed. Additional loss may be avoided
by obt~ning road material from outside Deadman
Creek. Some compensation wi 11 occur through improved
habitat downstream from the dams.
E-3-514
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4.4 -Mitigation Plan
(X)
(xi )
Marten
Forest habitat supporting approximately 130 marten
wi 11 be lost to the impoundments access and transmis-
sion corridors. Se 1 ecti ve c 1 eari ng and narrowing of
the transmission corridor could reduce the impact to
marten by allowing free movements across the corri-
dor. Marten movements are i nhi bi ted by open areas
(see Section 4.3.4). No further avoidance, minimiza-
tion, rectification, or reduction is possible for
loss of preferred coni fer forest habitat. Further
mitigation would require compensation.
Raptors and Raven
Ravens are not limited by nest sites and are not an-
ticipated to require any specific mi ti gati on mea-
sures.
Clearing and filling of the impoundment wi 11 destroy
the following nesting locations of raptors: 3 bald
eagle, 2 goshawk, 7 golden eagle, and 1 gyrfalcon.
An unknown number of other eli ff-and tree-nesting
locations for owls and small hawks will also be
destroyed. Loss of tree-nesting locations wi 11 occur
during impoundment clearing, and could be temporarily
avoided by leaving nest trees (and adjacent perch
sites for bald eagle).
The actual number of breeding pairs of golden eagles
affected wi 11 be 4 or 5, as some of the nesting
locations are alternate nest sites and unlikely to be
used simultaneously. Most of the suitable cliff-
nesting habitat upstream from the Watana dam wi 11 be
lost. Total avoidance of this impact is feasible
only through the no-project alternative. Destruction
of the golden eagle nesting location in Borrow ~teE
could be avoided. No minimization, rectification, or
reduction is possible for other tree-or cliff-
nesting locations. Compensation could be provided
through the creation of cliff habitat, repositioning
of some nests, and providing artificial platforms,
nests, and/or cavities for tree-nesters. The success
of such methods and a description of the techniques
av ai 1 ab 1 e appear in Appendix 3. I.
Without mitigation, salmon runs are expected to de-
crease in the reach downstream from Devil Canyon as
far as Talkeetna. This may affect bald eagles in
E-3-515
4.4 -Mitigation Plan
this reach. The impact wi 11 be ~ntirely av~ded by
maintenance-level mitigation for salmon in this reach
(see Section 2.4.4[a]).
(xii) Waterbirds
The impoundment will flood riparian and river breed-
ing and/or feeding habitats for spotted sandpiper~
mew gull, harlequin duck, common and red-breasted
merganser, semipalmated plover, wandering tattler,
arctic tern~ and dipper. Additional losses of nest-
ing habitat in forests will occur for goldeneye and
lesser yellowlegs. Trumpeter swans are not known to
nest in any of the affected project areas. No avoid-
ance, minimization, rectification, or reduction is
possible. Densities of all waterbird species are low
in the middle basin, and compensation on a scale
comparable to loss is not realistic.
(xiii) Terrestrial Birds
The impoundment and other project facilities will
'cause loss of habitat for some estimated 103,000
small terrestrial birds. No avoidance is possible.
Reduction of loss in the most densely populated and
high diversity habitats is possible through aligning
access and transmission corridors away from these
habitats. Although numerical losses are large and
proportionate losses to the middle basin populations
of some species are significant, specific in-kind
compensation for each species on the exact seale of
project impact does not appear realistic. Habitat
enhancement measures for other species wi 11 provide
some in-kind mi ti gati on for certain assemb 1 ages of
small birds, although the most highly affected
communities (i.e., forest birds) wi 11 not be provided
mi ti gati on in this way.
(xiv) Small Mammals
The impoundment and other project faci 1i ties wi 11
cause a si gni fi cant loss of habitat for some species
of small mammals. No avoidance is possi b1e. All
species are quite common in other areas, and on 1 y
species restricted to forested habit at s (i .e.. red
squirrel, porcupine, snowshoe hare, and pygmy shrew)
would lose a large proportion of potential habitat in
the basin. Reduction of loss to these species may be
accompli shed by aligning the access and transmission
E-3-516
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4.4 -Mi ti gati on Plan
(b)
corridors away from forest habitat. Specific in-kind
compensation for each species does not appear to be
realistic. Habitat enhancement measures for other
species wi 11 provide some in-kind compensation for
certain assemblages of small mammals. The most
severely affected species, mentioned above, wi 11 not
be provided mitigation in this way.
Mortality Factors
(i) Hunting and Trapping Mortality
Improved access to the middle basin is anticipated to
have a negative impact on some wildlife populations
by increasing mortality from hunting and trapping.
Protection conferred through management by the ADF&G
varies between species and areas.
Moose, caribou, and Dall sheep are considered high
profile and high priority species. Census data
collected annually by ADF&G wi 11 provide data suffi-
cient for management through regulation of harvest
for these speci es. Harvest of Oa ll sheep i s st ri n-
gently controlled, and nearly all legal rams are
currently harvested each year. The legal take for
this species is not likely to change, although, with
improved access, demand may increase. The di stri bu-
t ion of harvest of moose and caribou wi 11 change with
improved access, effectively distributing the take
over 1 arger portions of the basin populations. The
harvest of caribou, like that of Dall sheep, is
contra 11 ed by permit. Because of increased success
anticipated to result from improved access, the
number of permits issued may be reduced. However,
assuming that management goals for the Nelchina herd
remain the same, the legal harvest allowed by ADF&G
is also likely to remain constant. Caribou subpopu-
lations with little or no current harvest will face
increased mortality, whi 1 e currently accessi b 1 e popu-
1 ati ons may experience a decrease in hunter take. If
management goals are altered to treat subpopul ati ons
of the herd, or to allow a change in herd size, the
legal harvest may either increase or decrease. Moose
harvest in the middle Susitna basin is not as strin-
gently regulated as Oall sheep or caribou harvest.
GMU 13 is a trophy management area for moose (only
bull moose with racks 36 11 across may be taken), a
strategy designed to protect the resource in an area
E-3-517
4.4-Mitigation Plan
with poor recruitment (see Section 4.2.1 [a]). With
present regulations, improved access will increase
the harvest of moose. Carry capacity wi 11 simultan-
eously decrease because of loss of habitat resulting
from development. Harvest regulations for moose are
likely to be changed to maintain the remaining popu-
1 ati on of moose in the middle basin. ADF&G manage-
ment can avoid negative impacts to moose caused by
increased harvest resulting from improved access.
Improved access could also increase the illegal take
of all species. For moose, caribou, and Dall sheep,
which are all monitored and managed to assure future
harvest opportunities, the impact of increased poach-
ing would be transferred to the legal users through a
decrease in the legal harvest.
Large predators ( b 1 ack bear, brown bear, and wo 1 f)
are considered competitors for the harvest of ungu-
lates and are frequently given lower priority or are
subject to control to insure future harvest opportun-
ities for more desirable species. The current take
of wolves is largely illegal. Improved access wi 11
reduce populations of these species in the absence of
specific protection. For users, harvest opportunity
will increase substantially unti 1 populations are re-
duced through overharvest or provided protection.
Considering reduced moose populations and increasing
harvest demand, reduced predator populations are
likely to be considered advantageous. Protection is
not likely unti 1 populations are reduced to a level
in accordance with harvest goals of ungulates.
Furbearers are rarely given specific protection.
Population data for furbearers are generally not
collected by ADF&G, and local areas subject to heavy
use are vulnerable to overharvest. The take of fur-
bearers and the risk of overharvest are controlled by
fur values. When fur values are high enough, access
is probably a less important factor, and even rela-
tively remote areas can become vulnerable to over-
harvesting. All furbearers are likely to become less
av ai 1 able above the d amsi tes bee ause of adverse popu-
lation effects of the project. Aquatic and semi-
aquatic furbearers wi 11 increase in abundance and
accessi bi li ty in the downstream reach between De vi 1
Canyon and Talkeetna. Some additional compensation
for upstream loss of beaver and muskrat habitat would
E-3-518
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4.4 -Mitigation Plan
be possible by enhancement of those sloughs which are
not reserved as salmon-spawning habitat (13 sloughs;
see Section 2.4.4[a]). Adjacent prime beaver habitat
would provide an adequate source of colonizing indi-
viduals for the river sloughs even with a substantial
annual harvest, as long as those adjacent areas
(which will remain inaccessible) maintain viable
populations.
Impacts of increased hunting and poaching mortality
resulting from increased access can be avoided during
construction by prohibiting access to nonproject per-
sonnel and by restricting and/or prohibiting hunting
and trapping by project personnel. During operation,
regulation of hunting and trapping wi 11 be under the
jurisdiction of the ADF&G and beyond the control of
the Power Authority, although the Power Authority may
assist the ADF&G in a number of ways. Some compensa-
tion for project impacts on wildlife populations can
be accomplished through improved management ability
conferenced by providing data obtained through moni-
toring programs to the ADF&G and by continued inter-
action between the agencies in i denti fyi ng and treat-
ing project impacts on both wildlife and user popula-
tions.
The powers of the Board of Game and the Commissioner
of Fish and Game to regulate harvest in response to
problems that might arise from the Susitna Hydroelec-
tric Project were outlined by ADF&G (1983a). The two
main problems. requiring a regulatory response were :
(1) increased harvest and (2) reduction of harvest-
able surplus. The following actions were identified
as being frequently taken:
-Shorten or close the season;
-Schedule the season at a time when animals are less
vulnerable or hunters are less efficient;
-Reduce the bag limit;
-Rest ri ct the harvest to specific sex and age
classes;
-Create a closed area;
E-3-519
4.4-Mitigation Plan
-Create a special use area, e.g., where motorized
vehicles are prohibited for hunting, thereby making
hunters less efficient;
-Use a permit hunt where a limited number of indi-
vuals are allowed to hunt; and
-Use a registration hunt where hunters must check in
before and after hunting. This allows careful
monitoring of hunter effort and harvest. When the
desired number of animals is harvested, the season
is closed by announcement.
ADF&G (1983a) indicates that each of these actions
has adverse secondary effects such as increasing the
cost of management or restricting user opportunities.
The typical sequence of events is : monitoring and
identifying a problem; regulatory changes are pro-
posed to the Board of Game by either the Department
of Fi sh and Game or any i ndi vi dua 1 or group; exten-
sive opportunities for public comment are provided;
and the Board then closes regulations to protect the
problem with the least adverse impact on users. The
Board typically responds within a one-yer period
(ADF&G l973a). If the problem is acute, the season
can be immediately closed by the Commissioner of Fish
and Game.
(ii) Additional Mortality
Mortality to populations of some species is likely to
increase significantly because of hazards associated
with project features. The access road wi 11 cause
accidental mortality of moose, caribou, some fur-
bearers, small mammals, and birds. The rail access
and increased train traffic on the Alaska Railroad
are likely to become substantial mortality factors
for moose. Tr ansmi ssi on lines are a source of
electrocution mortality for large raptors and colli-
sion mortality for swans. The selected transmission
tower and line configuration is such that little
possibility of electrocution exists. However, the
possibility of electrocution remains along the tem-
porary 34-kv construction transmission line to be
built from Cantwell to Watana vi a the Denali
Highway.
E-3-520
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4.4 -Mitigation Plan
The significance to wildlife population levels of
mortality because of project features cannot be
predicted at the present time. Monitoring of mortal-
ity levels and modeling of their population effect
would allow a more thorough analy~s of their signif-
icance. For moose and caribou, any significant im-
pact would be transferred to users through regulation
to maintain vi able populations.
Electrocution can be totally avoided through proper
pole/line configurations. No avoidance is possible
for other mortality sources. Mortalities caused by
collision with vehicles could be minimized through
regulation of traffic when caribou are present in
1 arge numbers and through decreasing the · maxi mum
speed limit at all seasons. Further reductions could
be conferred through mini mi zing or prohi biting pri-
vate vehicle traffic, bussing employees to their work
sites, and/or reducing the frequency of project
vehicle traffic through a traffic-scheduling and
control program.
The destruction of nuisance animals wi 11 be a source
of mortality for bears, foxes, and wolves. The crea-
tion of nuisance animals will negatively affect the
wildlife populations, the health and safety of proj-
ect personne 1, and the over a 11 cost of the project.
Bears, with their 1 ow reproductive potentia 1, 1 ow
densities, and large home ranges, wi 11 be susceptible
to severe population-level impacts. The impact can
be avoided only through strict enforcement of state
regulations prohibiting feeding of wild animals;
fencing all construction camps and landfills; incin-
erating all putresci ble kitchen waste daily; covering
solid waste landfills with soi 1 daily; providing
secure garbage cont~ners in work areas and requiring
their use by emp 1 oyees and adequate c 1 eani ng and
emptying schedules; assigning personne 1 responsi-
bi lity for maintaini,ng clean work areas; and strictly
enforcing all related regulations. During construc-
tion of the trans-Alaska oil pipeline, workers were
prohibited from feeding animals and infractions were
treated through immediate firing. Infractions of
this type increase the vulnerability of all project
personnel to mauling and disease, and the problem
must be dealt with seriously. No amount of facility
m~ntenance or incorporation of specific design
E-3-521
4.4-Mitigation Plan
features will eliminate this impact if project per-
sonnel are not adequately informed and cont rolled.
Additional problems commonly arise when comprehensive
garbage incineration plans are not adequately imple-
mented. The most typical shortcoming is careless
i nci nerati on. Incinerators must be large enough or
numerous enough to ensure that garbage is completely
burned and not just charred. The project construc-
tion facilities, village, and campsites should also
be fenced securely and gates monitored to maintain
the effectiveness of fencing. In addition to the
above mi ti gati on measures, a worker orientation pro-
gram including briefings on feeding regulations and
project site cleanliness would assist in avoiding
this impact. An animal control strategy with trained
personnel should also be incorporated into project
design to allow a timely and effective handling of
any wildlife problems which may develop during
construction.
(c) Disturbance Impacts
Disturbance is likely to reduce productivity at specific den
sites of foxes and wolves and nest sites of swans and rap-
tors. In addition, disturbance by low-flying aircraft,
particularly helicopters, may have an effect on population
productivity of ungulates. Females in late pregnancy and
young animals are particularly sensitive. These impacts can
be partly avoided through the development of guidelines
restricting qround and air activity in identified sensitive
areas. Protection criteria for Alaskan raptors are given in
Table E.3.168.
Disturbance of bears in dens during winter months will cause
direct mortality of individuals who abandon their dens. Be-
cause locations of all dens in the project area may not be
known, restrictions of ground activity in identified sensi-
tive areas will only partially avoid this impact.
Di sturbance of Da ll sheep at the Jay Creek mi nera 1 1 i ck by
clearing activity before flooding, boat traffic on the
impoundment, and low-flying aircraft may cause abandonment
of the lick which could possibly result in a decreased
carrying capacity in the Watana hills population's range.
This impact can be avoided through regulation of access and
air traffic in this area.
E-3-522
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4.4 -Mi ti gati on Plan
4.4.2-Mitigation Plans and Monitoring Investigations
This discussion describes continued study progams and the mi ti ga-
t ion plans incorporated into project design. A tabular summary
of the mitigation plans isprovided in Table E.13.178. Section
4.4.2(a) identifies the data req~red during and after construc-
tion to ensure appropriate types and levels of mitigation and to
identify hypothetical and unanticipated impacts. Section
4.4.2(b) describes the mitigation plans which have been incorpor-
ated into the project design as a result of the impact analysis.
Section 4.4.2(c) contains a brief description of residual or
untreated impacts.
(a) Continued Monitoring and Study Needs
Many of the mitigation plans require current data which must
be provided through continuous monitoring of wildlife dis-
tribution and/or population levels throughout the construc-
tion phase, and, in some cases, throughout the license per-
iod. Individual studyneeds are listed below.
(1) Data on the frequency and location of access road and
railroad mortality wi 11 be continuously collected to
allow an analysis of population effects on moose and
caribou'. Data for moose mortality will be used in the
modeling approach (Mi ti gati on Plan 7) to assess its
importance and allow full mitigation through enhance-
ment (Mitigation Plan 6). Mortality data for caribou
wi 11 also be used to assess its importance to the
population and to assist in scheduling traffic pat-
terns (Mi ti gati on Plan 12).
(2) Data on changes in vegetative cover in the downstream
floodp1ain.between Devil Canyon and Cook Inlet are
required to identify unpredictable changes in the
availability of early successional habitats and to
verify the success of mitigation through habitat
enhancement plans for moose (Mitigation Plan 6 below).
Low-level aerial photographs of the floodplain between
De vi 1 Canyon and Cook In 1 et wi 11 be taken every 10
years throughout the license period and compared with
photos from a flight to be made in 1988-1989 prior to
filling to determine the relative amounts of early
successi anal habitats.
(3) Data on movements and population size of caribou are
required throughout the license period to identify
unanticipated impacts and to provide information for
traffic scheduling (Mi ti gati on Plan 12).
E-3-523
4.4-Mitigation Plan
(4)
(5)
(6)
Particular attention should be placed on assessing the
i mp act of the impoundment as a barrier, impediment, or
hazard to movement. The status of the herd wi 11 be
moni tared before, during, and after the construction
phase to determine impacts on range use, productivity,
disturbance, and road effects. This wi 11 require
i nvesti gati ons throughout the license period.
Records of impoundment crossings and impoundment-
caused mortality during the open-water period are
required. Impoundment surveys would identify possible
hazards to wildlife from floating debris and allow
avoidance of impacts through removal described in
Mitigation Plan 9. Records of impoundment-caused
mortality wi 11 be used to assess the impacts of such
mortality on wildlife populations and the secondary
impacts to carrying capacity for caribou.
Data on the seasonal use of the Jay Creek lick and the
distribution of use within the lick are required prior,
to inundation of the lower portion of the lick to·
assess changes in lick availability and value to Dall
sheep and moose. In 1983, ground observations of the
lick wi 11 be conducted. The potential for soi 1 leach-
; ng wi 11 be addressed by collecting 30 soi 1 samples~
20 from various locations within the lick above and
below maximum operating level (2190 feet) and 10 from
nearby control soils. These samples wi 11 be analyzed
in a commercial laboratory for sodium, potassium,
calcium, and magnesium. The collections and tests
wi 11 be repeated three years after inundation to
determine whether 1 eachi ng has occurred. This wi 11
provide data to determine the appropriate level of
mitigation (Mitigation Plan 13).
Information on the locations of black and brown bear
dens and active fox and wo 1 f dens is required to
identify sensitive areas in which major ground and
aerial activity will be controlled (Mitigation Plan
10). This wi 11 require i nvesti gati ons of brown bear
and b 1 ack bear and spring aerial surveys for active
wolf and fox dens throughout the construction phase.
(7) Investigation of wolf populations is required to
identify secondary impacts on ungulate populations and
to identify hypothesized population-level impacts to
wolves. Data wi 11 be used to determine the need for
compensation for project impacts. This wi 11 require
E-3-524
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4.4 -Mitigation Plan
studies throughout the construction phase and three
years into the operation phase of the Watana project.
(8} Detailed information on beaver di stri buti on in Deadman
Creek and in the downstream floodplain between Devil
Canyon and Talkeetna before and after construction is
· required to determine the level of downstream mi ti ga-
t ion required. Such data wi 11 be collected throughout
the license period in order to assess the effects of
various flow releases downstream.
(9} The locations of active raptor nests must be deter-
mined each spring during the construction phase to
identify sensitive areas in which aerial and ground
activity wi 11 be restricted (Mi ti gati on Plan· 10}.
Surveys wi 11 continue during operation to provide data
on the need for continued mitigation through nest
habitat enhancement and provision of artifical nest
sites (Mi ti gati on Plan 22). Surveys wi 11 continue
until 100 percent mitigation has been realized.
(10} The locations of swan nests in development areas must
be determined each spring throughout the construction
phase to identify sensitive areas in which major
ground and aerial activity will be prohibited (Mitiga-
tion Plan 10).
(11} A monitoring program wi 11 be implemented and continued
throughout the license period to document the browse
production of 1 ands enhanced for moose (Mi ti gati on
Plan 6). Research on the proposed Alphabet Hills burn
(scheduled for August 1983) has already begun. Field
data on browse production in transmission corridors
and other disturbed habitats, enhanced lands, and the
downstream floodplain wi 11 allow the modeling approach
(described in Mitigation Plan 7 and Section 4.3.1
[a][iii]) to provide an evaluation of mitigation
success and indicated additional needs.
Mitigation Plans
(1) Impoundment clearing activities will not begin until
two or three years prior to filling. Patches of
riparian vegetation will be left uncleared until just
prior to filling. Delayed clearing wi 11 temporarily
avoid impacts of habitat loss to marten, moose, and
black bear. Avoiding clearing during the winter and
early spring months would prevent disturbance of moose
E-3-525
4.4 -Mitigation Plan
during calving and brown and black bears during hiber-
nation. Precise clearing schedules wi 11 be determined
in consultation with resource agencies.
(2) Habitat loss for all species will be minimized through
use of side-borrow techniques for road construction
(described in Section 3.4.2[a][i]), depositing spoil
in future impoundment areas or depleted borrow sites,
and con so 1 i dati on of project f aci 1 it i es. Si de-borrow
techniques wi 11 reduce the number of borrow sites
required for construction of the access road between
the Denali Highway and Watana. Airport, construction
sites, and camp structures will be as confined and as
close to the dams as possible.
(3) Revegetation and ferti li zati on of disturbed sites
(described in Section 3.4.2[a][i]) will minimize the
period of temporary habitat loss. In particular, it
wi 11 provide spring and winter forage for moose for
2 to 20 years after the initiation of reclamation.
Bears are typically attracted to such sites by the
high productivity and early availability of spring
forage. In some areas, this may increase the fre-
quency of bear/human encounters, with possible nega-
tive impacts (see Mi ti gati on Plans 14, 15, 16).
(4) Minimization of habitat loss to the transmission
corridor wi 11 be accomplished by selective clearing in
the corridor (Figure E.3.85), leaving small shrubs and
trees, and by leaving a 35-foot (10m) wide strip of
vegetation up to 10 feet (3m) tall. Additional
rectification for habitat loss wi 11 be provided by
allowing vegetation to grow to a height of 10 feet (3
m) during operation. The transmission corri dar design
is described more completely in Section 3.4.2. This
design wi 11 actually enhance habitat for moose and
other wildlife preferring vegetation types in early
successi anal stages. Impacts of habitat loss from
other project features wi 11 be compensated for through
increased carrying capacity for moose provided with
this corri dar design. Many other species (marten,
hare) wi 11 a 1 so benefit from this corridor design
because the retention of cover in the corridor wi 11
present less of a psychological or visual barrier to
movements.
(5) Habitat alteration which wi 11 occur downstream from
the Devil Canyon dam will be reduced through the use
of multilevel intake structures that will maintain
river temperatures as close to normal as possible (see
E-3-526
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I
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4.4 -Mi ti gati on Plan
(6}
Section 2.4.2}. This wi 11 m1n1m1ze problems of vege-
tation frosti.ng and blockage of movements by open
water in winter.
Carrying capacity for moose and bears can be improved
on most 1 ands through the use of burning, logging,
vegetation crushing, or land clearing. These methods
allow development of early successional vegetation
which has higher browse production (and therefore
carrying capacity) than the existing 1 ate-successi anal
vegetation types. Each of these methods has certain
advantag,es and disadvantages. Controlled burning is
usually the most economical and results in hi g;her
browse production than the other methods because
nutrients are immediately released to the soil, and
soi 1 s are warmed by greater i nso 1 ati on (Viereck and
Schandelmeir 1980}. Burning. a.lso produces higher
berry production than other methods (Fri-edman 1981}.
However, controlled burning is often impractical
because of land ownership and logistic problems.
Logging can also increase browse production, particu-
1 arly when the soi 1 is scarified in summer (Zasada et
al. 1981}. Logging is not feasible in some areas
because of topography or access and is usually more
costly than burning. Vegetation crushing has been
used on the Kenai Peninsula to _improve moose habitat
(Regelin 1982}. Access and topography also limit the
use of crushing to certain areas.
For purposes of provtdi.ng an estimate of the number of
acres of land required for mitigating this impact and
the cost of these measures, the following mitigation
scenario is presented:
- A controlled burn wi 11 be conducted on state 1 ands
north of the Susi tna Ri ver on the east side of
Watana Creek. A total of 6400 acres of woodland
coni fer forest in several separate stands wi 11 be
burned to improve both browse and berry production.
The browse production in woodland conifer stands is
approximately 10 kg/ha {Table E.3.92). Low shrub
stands, which would result from the burning effort
(Figure E.3.117), provide appro,ximately 30 kg/ha.
Burning of 6400 acres would thus provide compensa-
E-3-527
4.4 -Mi t1 gati on Plan
tion for 12,800 acres of lost habitat. Si nee browse
production begins to decrease after about 12-14
years (see Figure E.3.117), the same or nearby areas
wi 11 be burned again after 15 years. The feasi bi 1-
i ty of this approach wi 11 be verified by long-term
research on the Alphabet Hills burn, which began in
1982. The Power Authority has already provided
support for pre-burn moose and vegetation studies of
the proposed Alphabet Hi 11 s burn area. Burning is
scheduled for August 1983.
-The Susi tna watershed in the reach between Watana
and Devi 1 Canyon currently supports low numbers of
moose. This area was considered for habitat en-
han cement measures. However, the area is 1 arge ly
tundra, tall shrub (alder), and mixed forest. Based
on current data, it is unlikely that browse produc-
tion in tundra or tall shrub stands could be sig-
nificantly improved, and mixed forest stands already
support high browse production (Table E.3.92). This
area is therefore excluded from consideration for
habitat enhancement.
-Sites exist near the Susi tna River floodplain down-
stream from Gold Creek which were cleared for agri-
culture but left unplanted. Early successional
vegetation has developed in these areas and they are
used by 1 arge numbers of moose in winter. The
browse production of these disturbed areas has not
been measured, but during moose surveys in November-
December 1982, more than 50 moose were often seen in
disturbed fie 1 ds of 1 ess than 640 acres. Browse
production in these dense stands of willows probably
begins to decline rapidly after 20 years. The
av ai 1 ability of browse and the duration of high
browse production in these areas wi 11 be determined
in 1983. For a preliminary estimate of the area
required to compensate for loss of moose browse, it
wi 11 be assumed that areas currently classed as
conifer forest have only one third the browse
production of cleared areas. The Power Authority
will improve moose habitat by clearing 16,000 acres
of state 1 and within 10 mi 1 es of the Susi tna River
in scattered patches. These areas wi 11 be c 1 eared
to mineral soil by stock~ling the cleared vegeta-
t i on i n wi ndrows. Assuming t ht browse product i on i s
improved three-fa 1 d for 16 years and that these
areas are cleared three times during the license
period, these 16,000 acres wi 11 compensate for the
1 oss of 32,000 acres of moose habitat to the i m-
E-3-528
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4.4 -Mi ti gati on Plan
impoundment areas. The exact location and number of
acres to be improved wi 11 be determined using data
from downstream vegetation studies and using the
habitat-based modeling approach described below
(Mi ti gati on Plan 7). If browse production is
greater than the 3-fold increase hypothesized above,
less area will be required. A 3-fold increase in
browse production is a very conservative estimate,
and a 5-to 10-fold increase may be possible in
some vegetation types.
Burning of 6400 acres in the Wat ana Creek area and
clearing of an additional 16,000 acres near the down-
stream floodplain wi 11 mitigate for the loss of 42,135
acres to the impoundments, temporary and permanent
structures. Clearing and maintenance of the transmis-
sion corridor wi 11 provide additional mitigation where
the corridor traverses vegetation types which would be
enhanced by periodic clearing (i.e., conifer forests).
It is possible that regulated flows may result in a
net increase in moose habitat along the downstream
floodplain during the license period through an in-
crease in early successional riparian vegetation. In
this case, no additional mitigation would be required
for downstream impacts. A monitoring program will be
implemented and continued throughout the license
period to document the browse production of the lands
enhanced for moose (see monitoring Plan 11). This
monitoring program will provide input into the
habitat-based approach being developed by the Power
Authority, and will result in an increase or decrease
in the number of acres managed as moose habitat,
depending on the level of mitigation achieved. Esti-
mated costs for the proposed browse enhancement mea-
sures are summarized in Table E.3.169 This flexible
approach to mitigation is designed to provide total
mitigation for habitat loss to moose.
The controlled burns described above will also enhance
habit at for bears. However, it wi 11 not fully compen-
sate for loss of early spring foods for bears, partic-
u 1 ar ly not i n years of berry crop f ai 1 ure .. It wi 11
increase the availability of fall foods for fatten-
; ng.
Additional enchancement and partial compensation for
loss of spring habitat for brown bears will occur in
revegetated areas and disturbed areas. The increased
productivity in these areas, particularly in revege-
tated areas, is attractive to bears in early spring
E-3-529
4.4-Mitigation Plan
and at all seasons because greater insolation creates
earlier green-up and increased availability of some
preferred plants.
( 7) As a compensation measure to mitigate for impacts to
moose, the Power Authority is developing a habitat-
based model in conjunction with the ADF&G, the USFWS,
the University of Alaska, and private consultants.
This approach wi 11 use a variety of data to determine
the impact of habitat loss on present and future moose
populations. Data requirements are presently more
completely in Section 4.3.l(a)(iii).
An estimate of the number of acres required to miti-
gate for habitat losses for moose will be determined
using this habitat-based approach and information from
continuing studies by the Power Authority. Preli mi-
nary estimates of the level of mitigation required are
given in Mitigation Plan 6 above based on the prelimi-
nary browse production figures presented in Section
4.2.1(a) (see also Appendix 3.H).
The model will also incorporate population data and
wi 11 be used to assess the significance of cumulative
impacts of habitat loss, mortality factors, habitat
alteration, and disturbance. The refinement and use
of, this model wi 11 allow 100 percent compensation for
impacts to moose. Development of the modeling ap-
proach should also be considered out-of-kind mitiga-
tion for species impacts which cannot be otherwise
addressed.
(8) The Power Authority will assist the Alaska Board of
Game in conducting a controlled moose hunt within the
project area to avoid over-browsing of the area by
di sp 1 aced moose. The need for such a hunt wi 11 be
assessed using the modeling approach described above.
Available energy and protein will be measured to
determine carrying capacity of adjacent range in 1983
and 1984. A census of the impoundment and adjacent
areas will be conducted just prior to clearing to
assess the status of the moose population relative to
carrying capacity. A hunt would be conducted if
studies determine that the receiving areas cannot
support displaced moose without degradation of carry-
; ng capacity.
(9) Hazards to movement created by the impoundment wi 11 be
reduced through clearing of the impoundment zone prior
to flooding and through a program of debris removal as
E-3-530
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4.4 -Mi ti gati on Plan
necessary to continue throughout the license period.
Monitoring of the impoundment during the open water
period wi 11 identify debris hazards.
(10) Sensitive wildlife areas identified in the monitoring
studies will be protected from disturbance from
project aircraft by the following guidelines and
measures:
Pi lots w·i 11 be required to maintain a mini mum
altitude of 1000 feet above ground 1 eve 1 except
during take-off and 1 andi ng throughout the basin.
-Aircraft 1 andi ngs wi 11 be prohibited within 1/2 mile
of the Jay Creek mineral lick between Apri 1 15 and
June 15.
-Aircraft 1 andi ngs wi 11 be prohibited within the
Nelchina caribou herd calving area in the Talkeetna
Mountains (see Figure E.3.93) between May 15 and
June 30.
-Aircraft 1 andi ngs wi 11 be prohibited within 1/4 mile
of known active wolf dens or rendezvous sites during
May 1 through July 31.
-Aircraft 1 andi ngs wi 11 be pro hi bi ted within 1/2 mi 1 e
of active golden eagle nests between March 15 and
August 31 each year (Table E.3.168).
-Aircraft 1 andi ngs wi 11 be prohibited within 1/4 mi 1 e
of active bald eagle nests between March 15 and
August 31 (Table E.3.168).
Aircraft 1 andi ngs wi 11 be prohibited within 1/4 mile
of active gyrfalcon nests between February 15 and
August 15 (Table E.3.168).
-An aircraft buffer zone of at least 0.25 mile or
1000 vertical feet will be established around lakes
used by trumpeter swans during the nesting season.
-All aircraft restrictions and schedules wi 11 be
provided to aircraft pi 1 ot s in a conci se manu a 1.
Ground disturbance of i denti fi ed sensitive areas wi 11
be avoided through the guidelines and measures de-
scribed below. For the purposes of this discussion,
minor ground activity inc 1 udes short-term reconn ai s-
sance and exploration type programs such as field
E-3-531
4.4-Mitigation Plan
inventories. Major ground activity involves large
numbers of personnel; equipment; surface disturbance;
noise; or vehicular activity; such as clearing, pad
construction, blasting, and facility construction.
Protection criteria for nesting raptors which are
currently accepted as guidelines by the ADF&G, and the
USFWS were developed for the proposed Alaska Natural
Gas Transportation System (Behlke 1980) by raptor
biologists in the state. These general criteria were
modified for application to the Susitna Basin based on
known phenology of nests and are presented in Table
E.3.168. Although there may be a very small amount of
nesting activity before or after these dates, the vast
majority of nesting attempts wi 11 be covered under the
proposed criteria. In general, the early nest period
is more sensitive and the criteria are more conserva-
tive in the early season, reflecting this difference.
-Known raptor nesting locations wi 11 be assumed to be
occupied unti 1 June 1 of each year, after which,
protection measures wi 11 be withdrawn for the re-
mainder of the year if the nest is documented to be
inactive.
-Major ground activity wi 11 be prohibited within 1/2
mile of the Jay Creek mineral lick between Apri 1 15
and June 15. The reservoir adjacent to the lick
will be closed to boat and floatplane use within 1/2
mile of the lick.
Clearing acti viti es in the impoundment area wi 11 be
restricted to nonsen~tive periods near areas i~en
tified as sensitive to disturbance (e.g., concentra-
tions of calving moose, brown and black bears,
denning wolves, migrating caribou, raptor nests,
etc. ) .
-Major ground activity will be prohibited within 1/4
mi 1 e of all known active bear dens between Sep-
tember 15 and May 15.
-Major ground activity wi ll be prohibited within 1/2
mile of waterbodies used by swans during the nesting
season and other times when swans are present.
-Ground activity will be prohibited within 1/4 mile
of known active wolf dens or rendezvous sites be-
tween May 1 and July 31.
E-3-532
p.--.
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4.4 -Mi ti gati on Plan
-Major ground activity wi 11 be prohibited within 1/2
mile of active golden eagles nests between March 15
and August 31, within 1/4 mile of active bald eagle
nests between March 15 and August 31, or within 1/4
mile of gyrfalcon nests between February 15 and
August 15 (Table E.3.168).
In aqdition to these general guidelines, two specific
nests are anticipated to be vulnerable to disturbance.
These are treated below.
The Watana-Devi 1 Canyon portion of the access road
between Mile 32.5 and Mile 35 cannot be realigned away
from golden eagle nesting location GE-18 because of
topographic and engineering considerations. To mini-
mize disturbance from construction activities, con-
struction within 0.5 mile of the nesting location will
be limited to the nonsensitive period (August 31-
March 14) if the nest is active (see Table E.3.168).
Disturbance after road construction wi 11 be kept to a
minimum by ensuring that no activities occur south of
the road or along the eli ff-top for a distance of 0.5
mile east and west during the sen~tive period.
It is not feasible to realign the railroad access
route farther away than 0.25 mile from bald eagle
nesting location BE-8 between Mile 2 and Mile 3 be-
e ause of topograph.i c ·· and engineering considerations.
If the nesting loc·ation is active, efforts will be
made to limit construction to the nonsen~tive period
(August 31-March 14) to minimize disturbance.
(11) Although complete avoidance of the impacts of altered
caribou movements and range use i s not possi b 1 e with
the route chosen, design changes in the access road
and realignment to minimize effects on current major
use areas of the Nelchina range will minimize or
reduce its impact. Although this alignment avoids
some areas for caribou calving, some cows that calve
in the mountains to the west of the road would sti 11
be affected. Changes in road alignment are described
in greater detail in Section 3.4.2[a][i]). Use of
side-borrow techniques wi 11 minimize ~hysical and
visual barrier effects of the road to caribou and
other species. This technique results in a finished
road profile less than 4 feet above original ground
level (see Figure E.3.83) and minimizes amount of
habitat lost to material sites .
E-3-533
4.4 -Mi ti gati on Plan
(12) The effects of vehicle traffic on caribou movements (a
more serious impact than the actua 1 presence of the
road) can be minimized by reducing the volume, speed,
or frequency of traffic on the road. Public access
will be prohibited during the construction period.
The Power Authority is currently revie~ng options for
reducing traffic volume. Further minimization of
impacts could be provided through bussing workers to
the site, allowing only convoy traffic, or reducing
the speed limit and volume of traffic during sensitive
periods. Because dust clouds behind vehicles add to
the visual effect on caribou, water trucks wi 11 be
used to control dust along the road during the con-
struction phase. Continued monitoring (Monitoring
Plan 3) will evaluate the residual impact (if any) on
caribou and the need for out-of-kind mi ti gati on for
caribou.
(13) If monitoring of Dall sheep (described in Section
4.4.2 [i]) indicates a population-level effect of
partial inundation of the Jay Creek mineral lick, new
soi 1 wi 11 be exposed to rectify the impact. Moni tar-
ing use and comparison of soil samples (Continued
Study 5) wi 11 allow evaluation of the effectiveness of
this mitigation.
(14) The impact of overharvest of game species with i m-
proved access wi 11 be avoided during construction by
prohi biting public access vi a the project road or air
field, prohi biting employees and their families from
using project faci li ties or equipment for hunting and
trapping, and by providing data from monitoring in-
vestigations (described in Section 4.4.2[i]) which may
assist the Alaska Board of Game in regulating hunting
and trapping activities in the area. During the
operation phase, the Power Authority wi 11 have no
control over harvest acti viti es but wi 11 continue to
provide any pertinent data to the ADF&G and assistance
in their management activities.
Studies will provide information on the bear popula-
tion and the distribution of bear harvest which will
indicate the need to recommend restrictions on bear
hunts to the ADF&G to protect brown and black bears.
Concentrations of bears may occur in some project
areas which wi 11 also receive regular human access and
presence. Regulations on either the season or the
location of the hunt could be used to protect bear
populations from overharvest.
E-3-534
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....
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4.4 -Mi ti gati on Plan
(15)
The Power Authority wi 11 recommended hunting and
trapping restrictions to protect wolves within the
project are,a and a 11 ow the formation of new home
ranges and hunting patterns. This waul d minimize the
secondary impact of social strife and upheaval caused
by the alteration of historical pack boundaries.
Further restrictions may be recommended for other
furbearers if data from ongoing i nvesti gati ons
indicate a need for protection.
The creation of nuisance ani rna 1 s wi 11 be avoided
through combined implementation of the following
garbage-contra 1 and education measures:
An Environmental Briefing Program for employees wi 11
be required (described in Appendix 3.B) and wi 11
include briefings on regulations prohibiting feeding
of animals and reasons for the restrictions.
-State regulations pro hi biting feeding of wi ld
animals wi 11 be strictly enforced.
-Construction camps and 1 andfi 11 s wi 11 be fenced with
bear-resistant fencing and gates wi 11 be moni tared
to ensure the effectiveness of the fencing.
-Secure garbage containers wi 11 be required in work
areas.
-Personnel wi 11 be assigned the responsi bi li ty for
picking up and disposing of all discarded refuse in
work areas and along roads .
-Putrescible kitchen wastes wi 11 be stored indoors
and completely incinerated daily or more often, if
required, in adequate incinerators.
-Solid waste 1 andfi 11 s wi 11 be covered with soi 1
daily, or as required by permit stipulations.
Wildlife problems may persist to a small degree even
with such precautions. Increased use of bear concen-
tration areas by humans (e.g., Prairie Creek) and
attraction of bears to some sites (e.g., revegetated
areas) wi 11 both increase bear/human conflicts. The
construction manager, wi 11 be instructed to develop an
animal control strategy directed at avoiding and
minimizing all project-related problems and to respond
promptly to any situations that arise.
E-3-535
4.4 -Mi ti gati on Plan
(16) Decreased avai 1 ability of salmon to bears wi 11 be com-
pletely compensated for by enhancement of 13 sloughs
between De vi 1 Canyon and the confluence of the Chul-
itna and Talkeetna rivers (see Section 2.4.4[a]).
Increased activity at Prairie Creek would be a second-
ary impact of the project that would have a negative
effect on brown and b 1 ack bears which make season a 1
movements to the area during salmon runs. The Power
Authority wi 11 assist resource management agencies in
assessing this impact and in preparing recommendations
for mitigating actions. Without protection, the
stream is likely to be developed for mining or for
recreati anal sites. The occurrence of bear/human
encounters is likely to increase in Prairie Creek, no
doubt to the detriment of both parties. Deli berate
recreational development would also be severely detri-
mental to the basin populations of bears who make
regular movements to Prairie Creek.
The impacts of decreased av~labi lity of ungulate prey
for brown bear, black bear, and wolf wi 11 be reduced
through measures to avoid, minimize, or compensate for
impacts to ungulate populations. However, it is
likely that predator populations wi 11 be reduced
through harvest as a management strategy to allow
increased harvest of ungulates by humans. Therefore,
complete mitigation of impacts is not planned for
these species.
Additional compensation for bears for reduction in
both spring forage and prey avai 1 ability wi 11 be pro-
vided through revegetation of disturbed sites (see
Section 3.4.2[a][i]). Bears are adaptable and may be
able to replace some prey in their diet through in-
creased consumption of vegetation. The occurrence of
disturbed and, in particular, revegetated sites wi 11
provide addi ti anal attractive forage for bears. In
areas of frequent human use, revegetated sites wi 11
have a potential negative impact (see Mitigation Plans
3, 14, and 15).
(17) Loss of habitat for aquatic furbearers wi 11 be mini-
mized by reducing gravel requirements through side-
borrow techniques and utilizing only Borrow Sites D,
E, I, J, and K. In addition, material for the access
road in the Deadman Creek area wi 11 be obtai ned if
necessary from small upland sites outside the Deadman
Creek drainage (Figure E .3. 37). Further mitigation
wi 11 be provided in the downstream fl oodp 1 ai n as de-
scribed in Mi ti gati on Plans 18 and 19 below.
E-3-536
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4.4 -Mi ti gati on Plan
(18) Mitigation for loss of habitat and a quantitative
assessment of potential beaver habitat wi 11 be pro-
vided by the development and testing of a model of
beaver carr yi ng capacity for the De vi 1 Canyon to
Talkeetna portion of the floodplain. Inputs to the
model wi 11 include data on hydrology, slough mor-
phology, and forage availability; and the results of
different flow releases and water temperatures on
availability of overwintering habitat wi 11 be tested.
Continued monitoring of beaver populations wi 11 test
the validity of the model and refine its accuracy.
The development of this model wi 11 also mitigate for
residual impacts on furbearers. ·
(19) Loss of habitat for aquatic and semiaquatic furbearers
(especially beaver) wi 11 be compensated for through
enhancement of sloughs in the reach between Devi 1
Canyon and the ,confluence with the Chulitna and
Talkeetna rivers. Thirteen sloughs in this reach wi 11
be managed as salmon spawning sloughs, and beaver are
likely to be actively excluded from these. Of the
remaining sloughs, the beaver model will indicate
enhancement measures req~red for colonization and
overwintering by beavers. Slough enhancement measures
wi 11 a.l so benefit muskrat, mink, and otter and may
pro vi de comp 1 ete compensation for aquatic and semi-
aquatic furbearers.
(20) The loss of raptor tree-nesting locations wi 11 be
temporarily minimized by delaying impoundment clearing
operations unti 1 the two or three years prior to fi 11-
ing and, thereafter, by leaving islands of vegetation
around known nesting locations. Clearing activities
wi 11 be scheduled to avoid the early nesting season.
Active nests wi 11 thereafter be protected by disturb-
ance guidelines outlined in Mi ti gati on Plan 10.
Destruction of the bald eagle nest in Deadman Creek
(BE-8) wi 11 be avoided through realignment of the
access road northwestward and westward to pass 0. 5
mile from the nest tree. This distance will also
minimize disturbance to the nesting p~r.
Destruction of the currently inactive golden eagle
nest (GE-11) located within Borrow Site E will be
avoided by not mining that area of the site. Disturb-
ance of the nest, if it becomes active, wi 11 be avoid-
ed by prohibiting mining of the site during the nest-
ing period, March 15 through August 31.
E-3-537
4. 4 -Mi t i gat i on P 1 an
(21) The unavoidable loss of raptor nesting locations wi 11
be fully compensated for by site enhancement and the
creation of artificial nesting locations. The tech-
nique is described with examples in Appendix 3. I. The
f o 11 owi ng specific measures wi 11 be taken.
-A combination of several of the enhancement measures
described in Appendix 3. I wi 11 be used to provide
artificial nesting locations for bald eagles until
at least four successful new eagle nests have been
established in the middle or upper basin. Bald
eagles have shown little reluctance to use nests
that have been reconstructed after having been blown
down (Olendorff et al. 1980). The nests that are to
be inundated wi 11 be reconstructed in adjacent
areas.
-Natural-appearing nests will be placed in appro-
priate trees (especially large balsam poplar) in
suitable habitat downstream from the damsite or
along tributaries such as Portage Creek (presently
unused by ba 1 d eag 1 es). Additionally, the canopies
of other trees wi 11 be modified by removing tops or
some upper limbs to make them more attractive as
nesting locations for bald eagles.
The success
insure that
i ngs occur.
approach is
of these measures will be monitored to
at least 4 successful bald eagle nest-
The estimated cost of this mitigation
summarized in Table E.3.171.
-Ten nesting platforms for golden eagles containing
artificial stick nests wi 11 be placed on the tops of
transmission towers as construction occurs (see
Figure E.3.117). Costs estimates are provided in
Table E.3.172.
-Nesting habitat for goshawks wi 11 be improved both
by providing arti fi ci al nests and by increasing the
edge effect in large forest stands (D. Weir 1982
Personal Communication and D. Roseneau, unpublished
data). Great horned and great gray owls commonly
use abandoned goshawk nests in Alaska (Roseneau and
Bente 1981), and wi 11, therefore, also benefit from
these measures. Twenty nest boxes for cavity-
nesting kestrels, boreal owls, and hawk owls will
also be provided and monit'ored. Cavities will be
created in the tops of several mature birch or
spruce trees in an additional attempt to attract
E-3-538
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4.4 -Mitigation Plan
hawk owls and other cavity-nesting birds. Estimated
costs of these mitigation measures are summarized in
Table E.3.173.
Nests that can be physically repositioned higher on
the cliff (at least 50 feet above maximum pool
level) and cliffs suitable for enhancement measures
wi 11 be i denti fi ed in 1983. Some otherwise suitable
cliffs have no 1 edges for nest building. Nesting
1 edges and perches can be created with exp 1 osi ves
and/or hand tools. Artificial stick nests (see
below) can also be provided on such sites. Cliff
enhancement measures wi 11 begin in 1984. Nesting
1 edges wi 11 be created on exposed cliffs using
small, shaped explosive charges and/or hand tools.
It may also be possible to attach metal and masonry
nest ledges to some eli ffs. The feasibility of
physically moving original nests to new points
higher on the cliff wi 11 be demonstrated and per-
fected using an inactive nest. Areas where bedrock
cliffs can be exposed by b 1 asti ng and digging away
overburden wi 11 also be identified for possible
future enhancement.
The success. of these measures wi 11 be determined
through annual monitoring efforts. A combination of
measures inc 1 udi ng subsequent modi fi cations wi 11 be
used unti 1 the number of successful new nesti ngs
equals or exceeds the number of nesting golden eagle
p~rs lost to the project.
(22) Electrocution of raptors by the temporary 34 kV trans-
mis~on line from Cantwell to the Watana site wi 11 be
avoided by emplo~ng pole/line configurations and
other safeguards proven effective in other parts of
North America (Olendorff et al. 1981). Special atten-
tion wi 11 be given to wi re-g appi ng and ground wire
placement (~gure E.3.118), armless configurations
(~gure E.3.119), and transformer installation (Figure
E.3.120). Perch guards (Figure E.3.121) and elevated
perches (Figure E.3.122) wi 11 be used if necessary to
further avoid e 1 ectrocuti ons. These measures wi 11
totally avoid this impact.
(23) Loss of forest habitat for black bear, marten, small
birds, and small mammals will be minimized through the
alignment of the access road and transmission corridor
to avoid most forest areas; through using the narrow-
est corri dar allowable; through mini mi zing the area
E-3-539
4.4 -Mitigation Plan
used for borrow extraction by side-borrow techniques
for road construction; and through con soli dati on of
facilities. loss wi 11 be temporarily avoided by
delaying reservoir clearing operations unti 1 two or
three years prior to filling. Habitat loss in the
transmission corridor will be minimized by selective
clearing and minimization of the width of cleared
areas. Inhibition of marten and small mammal move-
ments across the corridor will also be minimized by
leaving a strip of vegetation along the centerline.
The alignment of the access corrdor has also been
altered to avoid four red fox denning areas.
(c) Residual Impacts
{i) Moose
The measures described above wi 11 pro vi de comp 1 ete
mitigation for habitat loss to moose through en-
hancement of adjacent areas and acquired replacement
lands. The carrying capacity of the middle basin
wi 11 be reduced and populations there may decrease.
The development of a carrying capacity model wi 11
allow an estimate of both carrying capacity and
current population level impacts. It will also
allow evaluation of the enhancement techniques and
determination of acreage required for enhancement.
The opportunity exists to further enhance moose
habitat downstream from Ta 1 keetna as out-of-kind
mitigation for residual impacts to other species
(see discussion of residual impacts on bears,
wolves, marten).
The model will also incorporate population data and
will allow an assessment of the population-level
effects of accidental mortality factors and harvest.
With this additional information, complete mitiga-
tion wi 11 also be provided for these impacts.
{ii) Car·ibou
The impacts of mortality factors and disturbance can
be minimized as described above, and no population-
level effects are anticipated. The likelihood of a
reduction in carrying capacity resulting from block-
age of movements by the impoundment is unknown.
Continued monitoring of the Nelchina herd wi 11 allow
evaluation of realized impacts. If unanticipated
E-3-540
-4.4-Mitigation Plans
impacts are demonstrated, mitigation will be pro-
vided. No in-kind mitigation would be possible for
P"' a demonstrated decrease in carrying capacity of the
Nelchina range. The Power Authority is evaluating
options for out-of-kind mi ti gati on in the eventual-
; ty that residual impacts are demonstrated.
-
{iii) Dall Sheep
{; v)
The impacts of disturbance at the Jay Creek mineral
lick wi 11 be fully avoided for through restrictions
on activity in the area. The need for further miti-
gation wi 11 be determined by continued study of lick
use and soi 1 composition. Demonstrated population-
level impacts will be mitigated for by exposure of
new soi 1 in the area ..
Brown Bears
The most significant potential impact of the Susitna
hydro development project on brown bears, the crea-
tion and destruction of nuisance animals, can be
prevented by the measures outlined above. Oi sturb-
ance impacts are also easily avoided or minimized.
Slough enhancement for salmon and cooperative man-
agement of 1 ands adjacent to Prairie Creek could
fully mitigate for 1 oss of these food resources.
The loss of habitat has been minimized as much as
feasible. No analysis of the value of habitat lost
is possible. Adequate methods for evaluating brown
bear habitat are not available. Brown bears are a
1 ow density species adapted to opportunistic utili-
zation of a large number of available food resources
in a very large home range. The impact of loss of
spring feeding areas cannot be assessed, and a popu-
lation-level effect ascribable to this impact would
be difficult to demonstrate. Although enhancement
measures for moose habitat wi 11 not fully mitigate
for 1 oss of spring forage for brown bears, burning
wi 11 increase abundance of berries, a major fall and
spring food of brown bears. Management and mi ti ga-
t ion plan conflicts militate against any in-kind
mitigation through replacement lands for brown bear.
Any reduction in the bear population is likely to
improve recruitment to moose and caribou populations
and wi 11 constitute out-of-kind mi ti gati on for these
species.
E-3-541
4.4 -Mi ti gati on Plans
(v) Black Bears
The above discussion of brown bear is also appli c-
able to black bear, except that black bear are
generally restricted to forested habitat, a si gni fi-
cant portion of which will be destroyed by the
Susitna hydro project. Residual impacts will,
therefore, be much 1 arger, and a si gni fi cant de-
crease in b 1 ack bear numbers and di stri buti on is
anticipated. Increased recruitment in ungulate
populations resulting from decreased bear densities
wi 11 constitute out-of-kind mi ti gati on for b 1 ack
bear.
(vi) Wolves
Di sturbance of wo 1 ves at dens wi 11 be avoided as
described above. Decreased availability of prey
wi 11 be minimized through the mitigation measures
proposed for ungulates. The Watana pack is likely
to be eliminated and the remaining packs' composi-
tion and ranges are likely to shift and fluctuate
unti 1 a new equilibrium is reached. Harvest manage-
ment goals for ungulates and mitigation plan con-
flicts militate against AOF&G management of replace-
ment lands for wolves. Considering the increasing
demand for harvest of ungulates and the possible
decreased opportunity for harvest of moose in the
middle basin, reduced wolf populations are likely to
be considered advantageous and wi 11 constitute
out-of-kind mitigation for moose and caribou.
(vii) Wolverine
Wolverine are wide-ranging and occur in low densi-
ties. Therefore, loss of habitat and increased
harvest are unlikely to cause a detectable decrease
in wo 1 veri ne abundance. The anticipated increase in
availability of carrion caused by higher turnover
rates in moose populations wi 11 mitigate for a
decrease in food resources resulting from habitat
loss. Further mitigation is not anticipated to be
necessary.
(viii) Aquatic and Semi aquatic Furbearers
Habitat loss upstream from the damsi tes wi 11 be
compensated for through habitat enhancement between
·E-3-542
I'"""
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4.4 -Mi ti gati on Plans
Devi 1 Canyon and Talkeetna. loss of stream habitat
in Deadman Creek will be minimized. The modeling
effort to be developed for beaver wi 11 allow deter-
mination of flows and slough enhancement required
for complete compensation for that species. Quanti-
fication of impacts and the extent to which mitiga-
tion is provided for muskrat, mink, and otter cannot
be determined from currently available data.
No compensation for increased harvest is possible
beyond the provision of enhanced downstream habitat.
If fur values are high, sustained high levels of
harvest may decrease populations. Adjacent prime
habitat, on which access wi 11 not be improved, will
continue to be a source of colonizing individuals as
long as those populations remain viable.
, (i x) Terrestrial Furbearers
( x)
Disturbance of red fox dens wi 11 be avoided. Loss
of forest habit at for a 11 species wi 11 be minimized.
Precise quantification of residual impacts is not
possible for any terrestrial furbearer. However,
only marten are expected to suffer substantial popu-
lation reductions and decrease in carrying capacity.
Residual impacts for marten are large. Enhancement
methods for moose wi 11 further increase lass of
habitat for marten. Opportunities for mitigation
for loss of forest habitat are limited both by
management priorities for economically more valuable
species and conflict with mitigation p 1 ans for
moose.
Raptors and Ravens
Ravens are not 1 i mi ted by nest sites and are not
anticipated to decrease in abundance ·in the middle
basin. Mitigation will completely compensate for
lass of nesting habit at and nesting 1 ocati ons for
bald and golden eagles, and gyrfalcons. A precise
assessment of impacts to other tree-nesting raptors
which will be negatively affected is not possible.
The increase in edge habitat near project faci li-
ties, the transmission corridor, and revegetated
sites wi 11 enhance habitat for acci pi ters (goshawks
and sharp-shinned hawk), thereby compensating for
loss of the limited available habitat in the im-
poundment area. Ground-nesting species are not
expected to suffer loss of nest habitat.
E-3-543
4.4-Mitigation Plans
(xi) Waterbirds
No in-kind mitigation is possible for loss of flu-
viatile and river habitat for waterbirds. Disturb-
ance impacts on trumpeter swan nests wi 11 be avoided
as described above. Combined loss of breeding habi-
t at and nest trees will reduce populations of water-
birds in the middle basin. However, waterbirds nest
in low densities throughout the middle basin, and
residual impacts represent a regionally insignifi-
cant loss of low-den~ty habitat.
(xii) Other Birds and Small Mammals
Numerical losses of small mammals and breeding birds
are large in the impoundment areas. Additional
losses will be minimized through alignment of the
access road through tundra and low shrub habitats
which support re 1 ati ve 1 y 1 ow numbers and species
richness. The mitigation measures proposed wi 11
leave large residual impacts, particularly for
species restricted to forest habit at s. Enhancement
programs . for moose wi 11 increase 1 asses for these
species, in both the lower and middle basins. No
in-kind compensation on the project site can be
obtained. Management priorities and conflicts
between mitigation plans prevent specific compensa-
tion on a scale comparable to loss. However, the
replacement 1 and acqui si ti ons and enhancement mea-
sures described in Mi ti gati on Plans 3, 4, and 5 wi 11
provide out-of-kind mitigation through the creation
and protection of habitat for birds and small mam-
mals of disturbed and early successional habitats.
4.4.3-Cost Analysis and Schedules
Schedules are indicated in the continued study and mi ti gati on
plans described in Sections 4.4.2(a) and 4.4.2(b) respectively.
To develop estimates of compensatory mitigation and study costs,
1982 cost estimates were prepared for each activity (Tables
E.3.169 to E.3.175). These cost estimates were based on unit
cost information derived from past and recent experience in
Alaska and elsewhere, escalated to arrive at a 1982 cost estimate
applicable to south-central Alaska. Costs for the mitigation
program were separated into two categories: costs incurred
during construction and costs incurred during operation. Operat-
ing costs are in annual 1982 dollar amounts averaged over the
50-year license peri ad. For the major compensatory mitigation
activities these costs are:
E-3-544
-
4.4 -Mi ti gati on Plans
Construction costs:
Downstream aerial photography
of vegetation
Browse enhancement programs
Bald eagle nest-~te
cornpensati on
Golden eagle nest-site
cornpensati on
Other raptors nest-site
cornpensati on
(E.3.170)
(E.3.169)
(E.3.171)
(E.3.172,
E. 3.174, &
E.3.175)
(E.3.173)
10,000
$10,340,000
$ 36,100
$ 161,200
Total Construction Costs
$ 9,400
$10,546,700
Average Annua 1 Operating Costs:
Downstream aerial photography
of vegetation
Browse enhancement programs
(E.3.170) $
(E.3.169) $
Total Average Annual Operating Costs $
1,000
82,000
83,000
These estimates do not include contingency costs or owner's
administrative costs.
The cost analysis and schedule for Mitigation Plan 5 (compensa-
tion for moose, brown bear, and black bear foraging habitat loss)
are given in Table E.3.169. The controlled burning program in
the middle basin wi 11 require $240,000 from project construction
costs for labor, equipment and logistics, and land leases from
private owners. No firm predictions can be made concerning lands
which may be made available or their cost. It is arbitrarily
assumed that 1/4 of the land to be enhanced through burning would
be leased from private landowners. For the purpose of this cal-
culation, the land is valued at $1,000/acre and the lease price
is assumed to be 5 percent of the purchase value per year. The
average annual cost of maintenance burning to obtain the optimal
seral ages of vegetation is $2,000/year over the 50-year license
period. The clearing program in the lower Susitna basin will
require $9,600,000 from construction costs for labor and equip-
ment. It is assumed that all necessary 1 ands (estimated as
16,000 acres, based on current data) can be obtai ned from state
or federal governments through interagency agreement. The aver-
age annual cost of maintenance clearing to maintain the optimal
seral age of vegetation is $384,000 per year for the 50-year
license period.
E-3-545
4.4 -Mi ti gati on Plans
The cost analysis and schedule for Continued Study Plan 2 (aerial
photography to measure changes in vegetation in the downstream
floodplain) are presented in Table E.3.170. Initial photography
in 1988-89 to establish a pre-project baseline wi 11 be funded
from project construction costs and wi 11 require an estimated
$10,000. Repeat photography will be taken five times in the
license peri ad (i.e., every 10 years) at an average annual
operating cost of $1,000.
Five programs of compensatory mitigation for the loss of raptor
nesting locations are casted in Tables E.3.171 to E.3.175. The
provision of modified and artificial nesting locations will be
funded initially as a construction cost. As indicated in Miti ga-
ti on Plan 21, efforts wi 11 continue unti 1 100 percent compensa-
tion in new active nesting locations has been achieved. This may
require some funding from operating costs in the first few years
of operation. No firm prediction can be made. However, the
total dollar costs are relatively small: for bald eagle,
$36,100; for golden eagle, $161,200; and for cavity-nesting
raptors, $9,400.
Other continued study and mitigation costs, which are an integral
part of project design, are included in project capital costs
(presented in Exhibit D).
4.4.4-Documentation of Agency Recommendations
This section documents agency recommendations or mi ti gati on
measures and facilities made to the Alaska Power Authority.
(i) Access Route Recommendations
The most extensive recommendations concerned the route of
access to the project (USFWS 1983, SHSC 1982, ADF&G 1980).
The agencies were in agreement on recommending that the
Denali Highway to Watana access route be avoided. Spe-
cific concerns addressed the substantia 1 disturbances in
the Deadman Creek area. USFWS (1983) pointed out the
importance of that area to calving moose, brown bear denn-
ing, caribou movements, wolf denning, beaver, and bald
eagle nesting. The SHSC (1982) and ADF&G (1980) further
indicated that routes crossing the Indian River and
through wetlands to the Parks ~ghway, routes on the south
side of the Susi tna, the Butte Lakes area, and routes
through the Prairie Creek-Stephan Lake-Fog Lakes area
should be avoided. Recommended routes include routing
between Watana and Devil Canyon on the north side of the
Susi tna (USFWS 1982, SHSC 1982, ADF&G 1980) and between
Devi 1 Canyon and Gold Creek on the south side of the river
(USFWS 1982, ADF&G 1980). Additional recommendations on
E-3-546
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4.4 -Mitigation Plans
access include rail access to the project site, to the
exclusion of a road connection (USFWS 1982, SHSC 1982),
and consolidation of the access and transmission corridors
(EPA1981).
The access corridor from the Denali Highway to Watana was
chosen to provide timely access to the project site.
Justi fi cation for the project design chosen appears in
Chapter 10 describing the design criteria for project
features. Rai 1 road access to De vi 1 Canyon has been i ncor-
porated into project design and uses the south side route.
Road access between Watana and Devil Canyon follows the
preferred north-side route. Rai 1 access alone is not
deemed feasible. The Denali Hi ghway-Watana route has been
relocated farther west to avoid the Butte Lake area, and
no project facilities will be located in the Prairie
Creek-Stephan Lake area or in the Fog Lakes area. Further
design changes and alternatives of the Denali Highway-
Watana route to avoid sensitive areas will minimize im-
pacts to wildlife species. Specifically, the use of
side-borrow techniques and restriction of road materials
borrow sites to areas outside the Deadman Creek area wi 11
minimize habitat loss. No special use areas for moose are
anticipated to be made unusab 1 e by the access corri dar
(see Section 4.3.3[a]). No indication that brown bear
denning habitat is in any way limiting has been presented
in ADF&G (1982e). Although no population-level effects on
caribou are anticipated to result from the presence of the
road, the alignment has been moved to the west of most
current major use areas. Continued monitoring of caribou
wi 11 assess the occurrence of unanticipated impacts and
allow mitigation through a traffic control program, if
necessary. The wolf dens near the access corri dar are
unlikely to be made unusable, and the Power Authority wi 11
assist the ADF&G in regulating access to active den sites
to av~d disturbance during critical periods as described
in Mi ti gati on Plan 10. Loss of beaver habitat wi 11 be
minimized as described in Mitigation Plan 17, and complete
compensation is anticipated downstream for unavoidable
impacts to beaver in Deadman Creek. The access route has
been realigned to avoid both destruction and disturbance
by traffic of bald e-agle nest 8. The transmission corri-
dor is routed and designed for ease of construction and to
improve maintenance and reli ability. A common corridor is
used between Watana and Gold Creek.
E-3-547
4.4-Mitigation Plans
(ii) Continued Monitoring Recommendations
A need for continued monitoring has been indicated by
USFWS (1983). Key components of the program recommended
include: (1) inclusion of appropriate federal, state, and
local agency participation; (2) full financial funding by
the Alaska Power Authority; and (3) utilization of the
monitoring program to modify, augment, or delete mitiga-
tion procedures as indicated by ongoing studies. In
particular, the USFWS (1983) made recommendations for
monitoring and removing floating debris on the reservoir,
continued studies and habitat models for beaver and pine
marten, monitoring of mi ti gati on for beaver to insure
levels anticipated, and providing data to assist ADF&G in
regulation of harvest.
The monitoring and continued studies programs are de-
scribed in Section 4.4.2(i). The inclusion of federal,
state, and local agencies is indicated in the mitigation
plans where appropriate. In particular, the development
of a modeling approach for management and habitat enhance-
ment of moose includes representation of the USFWS, ADF&G,
and the University of Alaska. All data from monitoring
wi 11 be provided to the AUF&G with recommendations regard-
; ng the regulation of harvest, which is entirely their
domain. The funding levels of the individual mitigation
plans are presented in Section 4.4.3. The fle~bility of
mi ti gati on plans to identify, measure, and respond to
hypothesi zed, unanticipated, and currently unmeasurab 1 e
impacts has been stressed. The process by which miti ga-
ti on wi 11 be refined and implemented is described in
Section 1.3. The structure for a review group including
agency, project, and subcontractor representation is also
outlined in that section.
Provisions to monitor and to remove reservoir debris
appear as Mitigation Plan 9. Monitoring programs for
beaver are outlined in Section 4.4.2(i). Continued moni-
toring of marten is considered an i neffi ci ent use of
avail able resources because of conflicts with mitigation
plans for higher priority species (see Section 1) and
because of the lack of jurisdiction of the Power Authority
in regulating the harvest of game on replacement lands.
The modeling program for beaver is described in Mitigation
Plan 18.
E-3-548
I '
f',--
,..
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-
4.4-Mitigation Plans
(iii) Environmental Briefings Program Recommendation
( i v)
( v)
(vi)
(vii)
USFWS (1983) expressed strong support for the Environ-
mental Briefings Program and recommended that it be a
mandatory requirement for all project personnel before
they begin work on the project.
The Environmental Briefings Program has been described
more completely and has been made a mandatory requirement
for project personnel.
Jay Creek Mineral Lick Recommendation
USFWS (1 983) recommended that the reservoir adjacent to
the Jay Creek mineral lick be closed to boat and float-
P 1 ane use. Such restrictions wi 11 be imposed on access
during the construction phase, as indicated in Mi ti gati on
Plan 10.
Garbage Incineration and Fencing Recommendation
USFWS (1983) strongly recommended adequate fencing and
garbage i nci nerati on and indicated the need to clearly
post and monitor gate closures. This is treated in detail
in Mitigation Plan 15.
Prohi bi ti on of Hunting and Trapping Recommendations
USFWS (1983) recommended that workers and their families
be prohibited from hunting or trapping while working in
the project area.
Mitigation Plan 14 describes the measures incorporated
into project de~gn to treat the pos~ble impact of over-
harvest of game. The Power Authority has no moral or
legal right to prohibit hunting or trapping on adjacent
state, federal, or private lands. However, control can be
exerci sed over the use of project equipment and f aci 1 i-
ties. Although the Power Authority can have no control
over harvest activities, they wi 11 continue to provide any
data from monitoring investigations to the Alaska Board of
Game to as~st in regulation of hunting and trapping.
Transmission Corridor Recommendations
In addition to con soli dati on of access and transmission
corridors (treated under access, above), the USFWS (1983)
E-3-549
4.4 -Mitigation Plan
recommended selective clearing, winter and helicopter
construction and maintenance, and controlled access along
the transmission line.
The transmission corridor has been re-routed to simplify
construction and maintenance and to increase reli ability.
While those concerns must dominate, the chosen design
minimizes overall disturbance. Selective clearing has
been incorporated into the design (see Section
3.4.2[a][ii]). High priority species to which summer
clearing would be detrimental (e.g., eagles and falcons)
will be protected by disturbance regulations presented in
Mitigation Plan 10. There is no plan at the present time
to control access along the transmission corridor.
Fencing would obstruct movements of game and is likely to
be ineffective unless monitored.
E-3-550
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r
REFERENCES -INTRODUCTION
Alaska Department of Fish and Game. 1980. Letter from K.B. Schneider
to N.K. Gutcher, R&M Consultants, Inc. November 26.
1982a. Statement of Policy on Mitigation of Fish and Game
Habitat Disruptions. Juneau •
1982b. Testimony of Commissioner R. Skoog to Alaska Power
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Alaska Department of Natural Resources. 1982. Testimony of
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Directors. April 16.
Alaska Power Authority. 1982. Susitna Hydroelectric Project Fish and
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ESSA/WELUT/LGL. 1982. Report on Susitna ~droelectric Project
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U.S. Fish and Wildlife Service. 1979. Letter from G. Hickman to
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1980. Letter from K. Schreiner to E. Yould, Alaska Power
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1981a. Letter to E. Yould, Alaska Power Authority.
December 17.
1981b. Letter from M. Monson to E. Yould, Alaska Power
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1982a.
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Letter from J. Morrison to E. Yould, Alaska Power
January 5.
1982b. Testimony by Regional Director LeRoy Sowl to the Alaska
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1982c.
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Letter from J. Morrison to E. Yould, Alaska Power
August 17.
1982d. Letter to E. Yould, Alaska Power Authority, October 5.
• 1983. Letter from K. Bayha to E. Yould, Alaska Power
--Authority, January 14.
E-3-551
REFERENCES-FISHERIES
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Acres American Incorporated. 1981. Susitna Hydroelectric Project 1980
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1982b. Susitna Hydroelectric Project: Transmission Line
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1982c. Susitna Hydroelectric Project: Transmission Line
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An c ho rage, A 1 as ka •
• 1982d. Susitna Hydroelectric Project: Fish and Wildlife
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pp
• 1982e. Susitna Hydroelectric Project: Access Plan
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Alaska Department of Fish and Game. 1972. Cook Inlet King Salmon
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Alaska.
• 1974. An Assessment of the Anadromous Fish Populations in the
--·upper Sus itna River Watershed between Devil Canyon and the
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1976. Fish and Wildlife Studies Related to the Corps of
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• 1978. Preliminary Environmental Assessment of Hydroelectric
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• 1980a. Inventory and Cataloging of Sport Fish Waters of the
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__ • 1981e. Phase 1 Final Draft Report Resident Fish Investigation
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E-3-553
1982e. Preliminary 1982 Fisheries Data. Letter from
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APPENDIX E3A
Fish and Wildlife Mitigation Policy
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APPENDIX 3.A
SUSITNA HYDROELECTRIC PROJECT -FISH AND WILDLIFE MITIGATION POLICY
NOVEMBER 1981
REVISED MARCH 1982
REVISED APRIL 1982
1 -INTRODUCTION
The fish and wildlife mitigation aspects of the Susitna project have
been addressed through a Fisheries Mitigation Core Group, a Wildlife
Mitigation Core Group, and a Fish and Wildlife Mitigation Review Group.
The two core groups consisted of staff members of Terrestrial Environ-
mental Specialists, consultants with expertise in special areas (cari-
bou, furbearers, anadromous fish, etc.), and a representative of the
Alaska Department of Fish and Game. The purpose of the two core groups
was to develop the technical specifics of the mitigtaion pol icy and
plans.
The purpose of the Review Group is to review and comment on the results
of the core g·roups. Agencies represented on the Mitigation Review
Group are:
Alaska Department of Natural Resources,
Alaska Department of Fish and Game,
U.S. Fish and Wildlife Service,
U.S. Environmental Protection Agency,
U.S. Bureau of Land Management, and
National Marine Fisheries Service.
A mandate of the Alaska Power Authority (hereinafter called the Power
Authority) charter is to develop supplies of electrical energy to meet
the present and future needs of the state of Alaska. The Power Author-
ity also recognizes the value of our natural resources and accepts the
responsibility of insuring that the development of any new projects is
as compatible as possible with the fish and wildlife resources of the
state and the habitat that sustains them, and that the overall effects
of any such projects will be beneficial to the state as a whole. In
this regard, the Power Authority has prepared a Fisheries and W"il dl i fe
Mitigation Pol icy for the Susitna Hydroelectric Project as contained
herein.
2 -LEGAL MANDATES
There are numerous state and federal laws and regulations that specif-
ically require mitig·ation planning. The mitigation policy and plans
contained within this document are designed to comply with the collec-
tive and specific intent of these legal mandates. Following are the
major laws or regulations that require the consideration and eventual
implementation of mitigation efforts.
Protection of Fish and Game (AS 16.05.870)
The Alaska state laws pertaining to the disturbance of streams impor-
tant to anadromous fish address the need to mitigate impacts on fish
and game that may result from such action. The pertinent portion of
item (c) from Section 16.05.870 reads as follows:
If the Commissioner determines to do so, he shall, in the
letter of acknowledgement, require the p~rson or governmental
agency to submit to him full plans and specifications of the
proposed construction or work, complete plans and specifica-
tions for the proper protection of fish and game in connec-
tion with the construction work, or in connection with the
use, and the approximate date the construction, work, or use
will begin, and shall require the person or governmental
agency to obtain written approval from him as to the suffi-
ciency of the plans or specifications before the proposed
construction or use is begun.
National Environmental Policy Act
The National Environmental Policy Act (NEPA) (42 USC 4321-4347) was
designed to encourage the consideration of environmental concerns in
the planning of federally controlled projects. Regulations pertaining
to the implementation of NEPA have been issued by the Council on En-
vironmental Quality (40 CFR 1500-1508: 43 FR 55990; corrected by 44 FR
873 Title 40, Chapter V, Part 1500). Items (e) and {f) under Section
1500.2 (Pol icy) of these regulations describe the responsibilities of
federal agencies in regard to mitigation.
Federal agencies shall to the fullest extent possible:
(e) Use the NEPA process to identify and assess the reasonable alter-
natives to proposed actions that will avoid or minimize adverse
effects of these actions u pan the quality of the human en vi ron-
ment.
(f) Use all practicable means, consistent with the requirements of the
Act and other essential considerations of national policy, to
restore and enhance the quality of the human environment and avoid
or minimize any possible adverse effects of their actions upon the
quality of the human environment.
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Federal Energy Regulatory Commission
Federal Energy Regulatory Commission (FERC) regulations also refer
directly to the need for mitigation actions on the part of the devel-
opers of hydroelectric projects (18 CFR Part 4). The following refer-
ence is quoted from Section 4.41 of the Notice of Final Rulemaking as
it appeared in the November 13, 1981, issue of the Federal Register (46
FR 55926-55953) and adopted. Exhibit E of the proposed FERC regula-
tions should include, among other information,
••• a description of any measures or facilities recommended by
state or federal agencies for the mitigation of impacts on
fish, wildlife, and bot ani ca 1 resources, or for the p rotec-
tion or enhancement of these resources •••
The regulations go on to require details concerning mitigation includ-
ing a description of measures and facilities, schedule, costs, and
funding sources.
Fish and Wildlife Coordination Act (915 USC 661-667)
Item (a) of Section 662 of the Fish and Wildlife Coordination Act
(FWCA) describes the role of the federal agencies in reviewing federal-
ly licensed water projects;
••• such department or agency first shall consult with the
United States Fish and Wildlife Service, Department of the
Interior, and with the head of the agency exercising adminis-
tration over the wildlife resources of the particular State
wherein the impoundment, diversion, or other control facility
is to be constructed, with a view to conservation of wildlife
resources by preventing loss of and damage to such resources
a'S well as providing for the development and improvement
thereof in connection with such water-resource development.
FERC will comply with the consultation provisions of the
FWCA.
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3 -GENERAL POLICIES TO BE CARRIED OUT BY THE APPLICANT
3.1 -Basic Intent of the Applicant
In fulfilling its mandate, an objective of the Power Authority is to
mitigate the negative impacts of the Susitna Project on the fish and
wildlife resources. This goal will be achieved through comprehensive
planning during the early stages of project development and through a
program of ongoing consultation with the appropriate resource agencies.
Si nee the Power Authority realizes that highly coordinated planning
will be necessary to achieve this goal, a decision-making methodology
has been developed to provide a framework for addressing each impact
and the mitigation options available. This methodology outline also
identifies the process for resolving conflicts that may develop between
the Power Authority and the resource agencies. The FERC will resolve-
any disputes which the agencies and the Power Authority cannot resolve.
It is the intent of the Power Authority to negotiate directly and
resolve conflicts with the concerned agencies.
The mitigation plan will be submitted by the Power Authority to the
FERC as a component of the license application. Prior to this, any
draft mitigation plans will be submitted to resource agencies for
formal review and comment. The final mitigation plan to be implemented
will be stipulated by the FERC. The responsibility for implementation
of the plan will be that of the Power Authority and will be carried out
by the Power Authority or any other organization charged with managing
the project as stipulated by the FERC.
3.2-Consultation with Natural Resources Agencies and the Public
In order to achieve the above-mentioned goals, it will be necessary to
provide opportunities for the review and evaluation of concerns and
recommendations from the public as well as federal and state agencies.
During the early stages of planning, representatives of state and
federal agencies will be encouraged to consult with the applicant and
the applicant • s representatives, as members of the Fish and Wildlife
Mitigation Review Group. Additional review and evaluation of the mit-
igation plan will be provided through formal agency comments in
response to state and/or federally administered 1 i cens i ng and permit-
ting programs.
The Power Authority will consider all concerns expressed by members of
the general public and regulatory agencies regarding the mitigation
plan. Input from the public will be given appropriate consideration in
the decision-making process as it pertains to the direction of the mit-
igation effort and the selection of mitigation options.
3.3-Implementation of the Mitigation Plan
The responsibility for implementation of the mitigation plan rests with
the Power Authority. Prior to implementing the plan, an agreement will
be reached as to the most efficient and effective manner in which to
execute the plan. The agreement will determine which organization will
serve to carry out various portions of the plan and will include stip-
ulations to insure adherence to the accepted plan.
The mitigation plan will include a brief statement of each impact
issue, the technique or approach to be utilized to mitigate the impact,
and the goal expected to be achieved through implementation of these
actions.
With the realization that a mitigation monitoring team will be neces-
sary to insure the proper and successful execution of the mitigation
plan and to determine its effectiveness, part of the plan will detail
the structure and responsibilities of such a monitoring body. The
successful organization and operation of a monitoring team will require
both funding and commitments. These matters will be resolved through
negotiation leading to mutual agreement among the various involved
parties after the mitigation plan is complete and the necessary level
of resources can be more accurately defined.
3.4 -Modification of the Mitigation Plan
As part of the mitigation plan, a monitoring plan will be established,
the purpose of which will be to monitor fish and wildlife populations
during the construction and operation of the project to determine the
effectiveness of the plan as well as to identify problems that were not
anticipated during the initial preparation of the plan.
The mitigation plan will be sufficiently flexible so that, if data
secured during the monitoring of fish and wildlife populations indicate
that the mitigation effort should be modified, the mitigation plan can
be adjusted accordingly. This may involve an increased effort in some
areas where the original plan has proven ineffective, as well as a
reduction of effort where impacts failed to materialize as predicted.
Any modifications to the mitigation plan proposed by the monitoring
team will not be implemented without consultation with appropriate
state and federal agencies and approval of FERC. It is the intent of
the Power Authority to reach agreement with the resource agencies con-
cerning modification of the p 1 an prior to seeking FERC approval. The
Power Authority will seek approval of the resource agencies, with FERC
as the final arbitrator. The need for continuing this monitoring will
be reviewed periodically. The monitoring program will be terminated
when the mitigation goals described in the plan have been achieved or
determined unachievable. Termination will be subject to FERC
approval.
-4 -APPROACH TO DEVELOPING THE FISH AND WILDLIFE MITIGATION PLANS
The develoment of the Susitna Fish and Wildlife Mitigation Plans will
follow a logical step-by-step process. Figure E.3.l illustrates this
process and identifies the major components of the process. Also iden-
tified in this figure are the organizations responsible for each step.
The following discussion is based on Figure 1 and uses the numbers in
the lower right corner of that figure for reference purposes.
The first step in the approach (Step 1) entails the i dentifi cation of
impacts that will occur as a result of the project. Each impacted
resource and the nature and extent of the impact wi 11 be defined. The
fish and wildlife resources will vary identification and may include a
population, subpopulation, habitat type, or geographic area. The
nature and degree of impact on each respective resource will be predic-
ted to the greatest extent possible. Ths step will be the responsi-
bility of the Core Group of the Mitigation Task Force.
Fallowing the i dent ifi cation of impact issues, the Core Group wi 11
agree upon a logical order of priority for addressing the impact
issues. This will include ranking resources in order of their impor-
tance. The ranking will take into consideration a varietyof factors
such as ecological value, consumptive value, and nonconsumptive value.
Other factors may be considered in the ranking if deemed necessary.
The impact issues will also be considered in regard to the confidence
associated with the impact prediction. In other words, those resources
that will most certainly be impacted will be given priority over impact
issues where there is 1 ess confidence in the impact • s actually occur-
ring. The result of this dual prioritization will be the application
of mitigation planning efforts in a logical and effective manner. The
results of the prioritization process will be reviewed by the Fish and
Wildlife Mitigation Review Group. If additional impacts materialize,
the plan will be modified as discussed in Section 3.4. This could also
include a shift in the prioritization of impacts.
Step 2 is the option analysis procedure to be performed by the Core
Group. The intent of this procedure is to consider each impact issue,
starting with high priority issues, and reviewing all practicable miti-
gation options.
Mitigation for each impact issue will be considered according to the
types and sequence identified by the CEQ {Figure E. 3. 2). If a proposed
fonn of mitigation is technically infeasible, only partially effective,
or in confict with other project objectives, additional options includ-
ing project modification will be evaluated. All options considered
will be evaluated and documented; this documentation will include an
identification of the impact issue, mitigation options, and conflicts
(if any) with project objectives. The result of this process will be
an identification and evaluation of feasible mitigation options for
each impact issue and a description of residual impacts.
Step 3 concerns the development of an acceptable mitigation plan. The
feasible mitigation options identified through Step 2, and a descrip-
tion and explanation of those deemed infeasible, will be forwarded to
the mitigation review group for informal agency review and comment.
Any recommendations received from the review group will be considered
by the Power Authority and the Core Group, prior to the preparation of
draft fisheries and wildlife mitigation plans. These draft plans will
be sent to the Fish and Wildlife Mitigation Review Group for comment,
revised and circulated to the agencies for formal review and comment.
The plans will then be revised and submitted to the FERC as a component
of the license application. The final fish and wildlife mitigation
plans to be implemented will be stipulated by the FERC following
discussions with the Power Authority and appropriate natural resource
agencies.
Additional items that may be addressed by the Core Group include an
identification of organizations qualified to execute the mitigation
plan and recommendations concerning the staffing, funding, and respon-
sibilities of the mitigation monitoring team. This will be done in
consultation with the Fish and Wildlife Mitigation Review Group.
Step 4 will be the implementation of the plan as agreed to during
Step 3. This will commence, as appropriate, following the reaching of
an agreement by all parties.
During the implementation of the plan, which will include both the
construction and operation phases of the project until further mitiga-
tion is deemed unnecessary, the mitigation monitoring team will review
the work and evaluate the effectiveness of the plan (Step 5). To
accomplish this goal, the monitoring team will have the responsibility
of assuring that the agreed upon plan is properly executed by the
designated organizations. The team will be provided with the results
of ongoin~ monitoring efforts. This will enable the team to determine
in which cases the mitigation plan is effective, where it has proven to
be less than effective, and also in which cases the predicted impact
did not materialize and the proposed mitigation efforts are unneces-
sary. The monitoring team wi11 submit regularly scheduled reports con-
cerning the mitigation effort and, where appropriate. propose modifica-
tions to the plan. If stipulated in the FERC license, such reports
would be distributed to FERC and state and federal regulatory agen~
cies.
In the event that plan modifications are recommended (Step 6), they
will be reviewed by a Core Group and appropriate options considered
(Step 2). The results of the option analysis will then be passed on to
the Power Authority and the resource agencies for negotiation of modi-
fications to the plan (Step 3). Following the reaching of an agreement
on the modifications, they will be implemented (Step 4) and monitored
(Step 5). Any modifications to the mitigation plan will not be imple-
mented without consultation with appropriate state and federal agencies
and approval of FERC. As discussed in Section 3.4, it is the intent of
the Power Authority to reach agreement with the resource agenices
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concerning modification of the plan prior to seeking FERC approval.
The Power Authority will seek approval of the resource agencies, with
FERC as the final arbitrator.
Following satisfactory implementation of any plan modifications and
documentation of evidence that the go~ls of the modification have been
reached, the mitigation planning process and monitoring will terminate
(Steps 7 and 8).
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APPENDIX E3B
Environmental Guidelines Memorandum
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APPENDIX 3.B
SUSITNA HYDROELECTRIC PROJECT
MEMORANDUM
October 25, 1982
TO: Dr. John Hayden, Acres American, Inc.
FROM:
Dr. Richard Fleming, Alaska Power Authority
Dr. Robert Sener, LGL Alaska Research Associates, Inc.
Dr. Larry Moulton, Woodward Clyde Consultants, Inc.
Mr. Robert Erick son, EDAW, Inc.
SUBJECT: Environmental Guidelines for Facility Siting, Design,
Construction, Operation and Rehabilitation
The attached environmental guidelines are provided for your review and
consideration. They were prepared cooperatively by our three firms and
represent a consensus of our professional judgement. We believe that
these guidelines, if followed, will make a major contribution toward
avoiding, minimizing, rectifying, and reducing adverse impacts of the
project on the environment.
We strongly recommend that these guidelines be followed for all future
engineering design and construction planning programs of the Susitna
Hydroelectric Project. Furthermore, we urge that the following steps
be taken immediately:
1. Provide the guidelines to all persons responsible for preparing
exhibits or sub-sections of the FERC license application. The doc-
ument should consistently reflect the incorporation of appropriate
environmental protection measures ·into the basic thinking under-
lying the project.
2. Make the guidelines available to Phase II contractors as part of a
special communication which emphasizes the importance of integrat-
ing environmental protection strategies into the earliest stages of
engineering design and construction plannning.
Please note that these are only guidelines. Site-specific facility
designs and construction plans should be considered on a case_-by-
case basis to ensure that project requirements are satisfied with
minimal adverse impact to the environment. To achieve this goal,
environmental specialists should work side-by-side with project
engineers in the same design offices, and in the field through pre-
construction siting studies.
SUSITNA HYDROELECTRIC PROJECT
Environmental Guidelines for Facility Siting, Design,
Construction, Operation , and Rehabilitation
Prepared by
LGL Alaska Research Associates, Inc.
Woodward-Clyde Consultants, Inc.
EDAW, Inc.
October 21, 1982
A. ALL FACILITIES
1. A 500-foot minimum-width buffer of undisturbed vegetation should be
maintained between a facility and any stream, lake, or wetland.
2. Siting should minimize requirements for clearing or removal of
vegetation.
3. Where removal of vegetation is required, organic overburden should
be segregated and stockpiled for use in subsequent rehabilitation.
Stockpiles should be placed in well-drained locations and bermed to
contain runoff. Depleted or non-operational borrow pits should be
used as overburden storage areas where feasible.
4. Structures should be consolidated to disturb the minimum necessary
area of ground surface.
5. Design should minimize gravel requirements by avoidance of wet
areas or permafrost zones, structure consolidation, and balanced
cut and fill.
6. Where gravel pads must be used, adequate prov1s1on for cross-
drainage should be made to avoid impoundment of sheet flow.
7. A minimum distance of 1/2 mile should be maintained between any
facility and the following:
-Salmon spawning area;
-Bald eagle nest;
-Golden eagle nest;
-Brown bear den;
-Black bear den;
-Wolf den;
-Dall sheep lambing area; and
-Mineral 1 ick.
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8. Blasting should avoid times and locations which are sensitive to
fish and wildlife. These times and locations should be determined
on a case-by-case basis by the environmental consultant and in
accordance with resource agency guidelines. Pro!)er sizing and
sequencing of blasting charges can minimize fish and wildlife
impacts. Streamside excavation should not be done by blasting.
Blasting procedures and schedules must be sufficiently flexible to
allow alteration at short notice for the protection of wildlife.
Alaska Department of Fish and Game blasting guidelines should be
followed.
9. Excavation spoil should be disposed of in the future impoundment
area of the dam under construction. Where haul distances prohibit
this, spoil should be used in the rehabilitation of depleted or
non-operational material sites, or for solid waste disposal site
. maintenance. Spoil retained for these applications should be
stockpiled in stable, well-drained locations, and bermed to con-
tain runoff.
10. Solid waste disposal sites should be established in stable, well-
drained locations. Siting should utilize existing excavations
such as depleted upland borrow pits. Intermittent drainages,
ice-rich soi 1 s, or other erosion-suscepti b 1 e features should be
avoided. Deposited material should be covered daily with non-
silty excavation spoil stockpiled for this purpose at the site.
Solid waste disposal site design and operation should conform with
guidelines established by the Alaska Department of Environmental
Conservation.
11. Facility siting should avoid thaw-susceptible areas {discontinuous
permafrost zones) capable of slumping or thermal erosion.
12. Where hydraulic erosion is unavoidable, appropriate measures
(ranging from filtration fabric to settling ponds) should be
employed,to minimize siltation.
13. Erosion-prone slopes should be ferti 1 i zed and dry-seeded with a
fast-growing native grass.
14. Equipment, structures, and materials should be removed from a site
prior to rehabilitation. The site should be graded to contours
which are consistent with surrounding terrain and allow complete
drainage with minimal erosion potential.
15. Where it can be demonstrated that erosion is not 1 ikely to be a
problem, restoration should emphasize fertilization and scarifica-
tion, and minimize seeding, to encourage the invasion of native
plants from the surrounding parent population. Where seeding is
employed, native grasses appropriate to the climate and geography
of the project area should be used.
16. A systematic program to avoid or mitigate project activity-related
impacts should be developed during Phase II. At a minimum, this
program should include the following components:
- A Petroleum and Hazardous Substance Plan which sets forth
detailed specifications for training of personnel and for pro-
cedures and equipment to ensure the safe storage, handling,
transportation, collection, and disposal of petrolet.m products
and hazardous substances. This program should include the
preparation of a Petroleum and Hazardous Substances Manual to be
used by all project personnel. Special attention should be
given to the design of this manual so that size, format, and
contents facilitate routine on-the-job use.
-An Environmental Briefings Program to familiarize project per-
sonnel with environmentally sensitive features of the stipul a-
t ions, and specific project ~olicies and restrictions regarding
protection of vegetation, fish. wildlife, and cultural
resources. The Environmental Briefings Program should be com-
bined with the project Safety Program and involve continuing
updates and reviews through regularly-scheduled weekly meetings.
The Environmental Briefings Program should be positive and
informative in nature, and use visual aids to stimulate inter-
est. The program should strive to explain why a certain feature
or organism is vulnerable to disturbance, and therefore, why
protective measures are needed in each case.
17. Storage containers for fuels and hazardous substances should be
1 ocated at least 1, 500 feet from water bodies and bermed to
contain 110 percent of the maximum volume to be stored. Contain-
ment areas should be lined with impervious material.
18. Project construction and operation activities should be planned
and scheduled to avoid or minimize disturbance to fish streams.
Where activities affecting fish streams cannot be avoided (e.g.,
construction of stream crossings), activities should be scheduled
for periods when fish are not present. Where stream crossings are
planned for winter construction, the thalweg, banks, and other
locational features should be identified and staked in the field
prior to snowfall or freeze-up.
B. CONSTRUCTION CAMPS
1. To minimize scavenging by birds and mammals, with resultant
adverse contacts between people and animals. all putrescible
kitchen wastes should be stored indoors in sealed containers, and
incinerated on the same day they are produced.
2. Camp incinerators should be properly sized and operated by trained
personnel to ensure that all putrescible wastes are completely
burned to mineral ash. Incinerator capacity should be carefully
specified to accommodate peak camp occupancy.
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3. Camp perimeters should be protected with animal-resistant fencing
designed and built to specifications provided by the environmental
consultant.
4. The liquid waste treatment system should be operated by State-of-
Alaska accredited personnel. Greywater must be treated along with
other liquid wastes. A regular effluent sampling and testing pro-
gram should be followed to ensure compliance with NPDES and State
of Alaska Wastewater Disposal Standards (18 AAC 72). Effluent
testing should be conducted by a State-of-Alaska certified water
quality laboratory. Effluent discharge to streams should be loca-
ted to achieve maximum dilution.
5. Wells should be established for potable water withdrawal. If
wells are not feasible at a given location, water should be with-
drawn from lakes. Streams should be considered only as a last
resort, and only after a dete:lllination is made on a case-by-case
basis that fish or wildlife wi 11 not be adversely affected by
water withdrawal, particularly during overwintering and reproduc-
tive periods. Intake structures should be designed to preclude
entrapment or entrainment of fish eggs or larvae.
C. ACCESS ROADS
1. Road design speeds should be kept to the m1mmum consistent with
project requirements, and should not exceed 40 miles per hour.
Lower design speeds allow greater flexibility for alignment
adjustments to avoid environmentally sensitive features, and re-
duce requirements for major road cuts. Lower design speeds also
enable routing to follow higher, drier terrain, thereby reducing
requirements for gravel extraction and fill placement in wetlands.
A 40-,mile-per-hour design speed will increase road safety and
2.
3.
4.
5.
6.
enhance recreational resource potential.
Road profile elevations should be minimized and side slopes made
sufficiently gentle to allow free passage of big game.
Routes should avoid wetland and riparian areas, and minimize
stream crossings and encroachments.
Road design should keep gravel extraction requirements to a m1 m-
mum by avoiding wet areas and emphasizing balanced cut and fill.
Where stream crossings cannot be avoided, they should be aligned
at right angles to the stream and located to minimize requirements
for bank cutting and streambed disturbance. Fish spawning and
overwintering areas within streams should be avoided by route
adjustments.
Bridges should be installed in preference to culverts or low-water
crossings (fords). Bridge supports should be located outside
active channels.
7. Culverts should be properly sized to accommodate all species and
age groups of fish utilizing that portion of the stream (see
Alaska Department of Fish and Game stream crossing guidelines).
8. Culverts should be placed to conform with the slope of the undis-
turbed streambed at the place of installation, and should not be
perched.
9. Low-water crossings should be used only where a stream will sus-
tain infrequent, light traffic. Such crossings should conform to
the slope of the undisturbed streambed and should be constructed
of materials that will preclude water percolating through rather
than over them.
10. Where stream crossings are planned for w·inter construction, the
thalweg, banks, and other locational features should be identified
and staked in the field prior to snowfall or freeze-up. Overwin-
tering areas of fish or aquatic mammals must not be disturbed
during winter construction.
11. All access roads not required for project operation or recrea-
tional purposes should be 11 put to bed .. as soon as they are no
longer required, if possible during the same season. Drainage
structures should be removed and the roadbed recontoured to a
stable configuration providing proper drainage. Rehabilitation
sho~d inlcude scarification, fertilization, and blockage with a
berm followed by a cut. Erosion-prone locations should be seeded
with fast-growing native grasses. Where impoundment of sheet flow
has occurred, non-operational roads should be structurally altered
to restore normal flow.
12. Road dust control should utilize water rather than oil or other
synthetic compounds. Water withdrawal procedures and sources for
dust control should be approved on a case-by-case basis by envi-
ronmental personnel following site-specific inspection.
13. Grading or other road maintenance activities should not push mate-
rial into streams. Culverts should be checked periodically and
kept free of ice and debris to avoid blocking flows. Special
attention to culverts is required immediately prior to, during,
and following spring break-up.
D. MATERIAL SITES
1. A detailed, site-specific m1n1ng plan should be prepared for each
borrow operation. Design should be· an interdisciplinary team
effort involving civil engineers and environmental specialists
experienced in design, construction, and permit requirements.
Mining plans should include all roads, facilities, mining tech-
niques, schedules, and rehabilitation procedures.
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2. Borrow areas required for dam and ancillary facility construction
should be sited in the future impoundment area of the dam under
construction.
3. Siting of borrow areas outside ~he impoundment zone should place
first priority on well-drained upland locations. Second priority
consideration should be given to first-level terrace sites.
Active floodplain and streambed sites should be avoided unless
they are within the impoundment area of the dam under construc-
tion. Stockpiling within active floodplains should be prohibited.
Floodplain gravel mining should follow the guidelines set forth in
the U.S. Fish and Wildlife Service 11 Gravel Removel Guidelines
Manual for Arctic and Subarctic Floodplains, .. 1980.
4. All material sites should be developed in phases by aliquots. The
phases should be prioritized to save until last those portions of
the site which are more sensitive from an environmental stand-
point.
5. First-level terrace sites outside the impoundment zone should be
located on the inactive side of the floodplain and mined by pit
excavation rather than by shallow scraping. Excavations should be
separated from the active floodplain by a 500-foot buffer of
undisturbed, vegetated terrain.
6. If wet processing is required, water withdrawal and discharge
locations should be carefully sited to minimize fish and wildlife
disturbance. Drawdown in overwintering pools used by fish or
aquatic mammals, and any disturbance to spawning areas, must be
avoided. Water intake structures should be designed to preclude
entrapment or entrainment of fish eggs or 1 arvae. Gravel washing
should employ recycled water. If pit dewatering is required
because of pondi ng or wet processing, settling poi nds should be
designed, operated, and monitored to ensure that NPDES standards
for discharge are achieved. Settling ponds should be designed and
sited to avoid fish entrapment. Water discharge should be direc-
ted in a manner that will minimize erosion. Energy dissipaters
should be used where necessary.
7. Abandoned access roads, camp pads, and airstrips should be used
wherever feasible as material sources for operations, in lieu of
expanding existing sites or initiating new ones. Where riprap is
required, material produced during excavation of the powerhouse,
galleries, and tunnels should be used if feasible.
8. Material site design features should facilitate restoration.
Sites should have irregular boundaries, including projections of
undisturbed, vegetated terrain into the site. Slopes should
incorporate a diversity of contours created during actual excava-
tion, rather than during restoration.
9. Where pending will occur, as in first-level terrace sites, irregu-
lar boundaries and slope contours should be accentuated. Islands
of undisturbed vegetated terrain should be left within the peri-
meter of the operational site.
10. Organic overburden, slash, and debris stockpiled during clearing
should be distributed over the excavated area prior to fertiliza-
tion. This includes sites which have ponded.
11. Once operational material sites are depleted or no longer re-
quired, they should be rehabilitated by the end of the next
growing season following last use.
E. TRANSMISSION CORRIDORS
1. Where they are not adjacent to an existing road, transmission
corridors should be constructed by helicopter support to avoid
unnecessary clearing of vegetation. In tundra locations where
clearing is not required for access. winter construction on a snow
base may be an acceptable substitute for helicopter-supported con-
struction, provided Rolligon or flat-tread Nodwell-type vehicles
are used. Transmission corridor development should avoid creating
an alternative access route for all-terrain vehicles.
2. Transmission line additions should be made adjacent to established
transmission corridors. Where transmission lines have a common
destination, they should follow a common route.
3. Transmission towers should not be placed in active floodplains and
should avoid streams and lakes by a minimum 500 feet.
4. Herbicides should not be used for vegetation control along trans-
mission corridors.
5. Transmission corridors should follow the forest edge (i.e., the
transition zone between forest and shrub or forest and tundra),
and avoid crossing wetlands.
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APPENDIX E3C
Preliminary List of Plant Species
Upper and Middle Susitna River
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APPENDIX 3.C: PRELIMINARY LIST OF PLANT SPECIES IDENTIFIED IN SUMMERS
OF 1980 AND 1981 IN THE UPPER AND MIDDLE SUSITNA RIVER
BASIN* (Ul, THE DOWNSTREAM FLOODPLAIN <Dl, AND THE
JNTERTIE (I) <AFTER MCKENDRICK ET AL. 1982)
Pteridophyta
Aspldlaceae
Dryopterls di latata (Hottm.J Gr~y
Dryopterls fragrans <L.> Schott
Gymnocarplum dryopterls <L.> Newm.
Athyrlaceae
Athyrium fi Jix-femina (L.> Roth
Cystopteris fragllls <L.> Bernh.
Cystopteris montana (Lam.> Bernh.
Matteuccia struthiopterls (L.l Todaro
Woodsia alpina (Bolton) s. F. Gray
Equisetaceae
Equlsetum arvense L.
Equlsetum fluviatile L. ampl. Ehrh.
Equisetum palustre L.
Equlsetum pratense L.
Equlsetum sllvaticum L.
Equisetum variegatum Schleich.
Eguisetum sp.
lsoetaceae
lsoetes muricata Our.
Lycopodiaceae
Lycopodium alplnum L.
Lycopodium annotinum L.
Lycopodium clavatum l.
Lycopodium complanatum L.
Lycopodium selago L. ssp. selago
Thelypteridaceae
Thelypteris phegopterls <L.> Slosson
Gymnospermae
Cupressaceae
Juniperus communis L.
Pin~ceae
Picea glauca (Moench) Voss
Picea mariana <Mill.> Britt.,
Sterns & Pogg.
Monocotyledoneae
Cyperaceae
Carex aquatllls Wahlenb.
Carex blgelowil Torr.
Carex cap! Jlarls L.
Carex canescens l.
Carex conclnna R. Br.
'shield fern
Fragrant shield fern
Oak tern
Lady fern
Fragile fern
Mountain tragi le fern
Ostrich fern
Alpine woodsia
Meadow horseta I I
Swamp horseta I I
Marsh horseta I I
Meadow horseta i I
Woodland horsetai I
Variegated scouring-rush
Horsetal I
Qui II wort
Alpine clubmoss
Stiff c I ubmoss
Running clubmoss
Ground cedar
F 1 r cl ubmoss
Long beech fern
Common juniper
White spruce
Black spruce
Water seds:~e
Bigelow sedge
Hairlike sedge
S I I very sedge
Low northern sedge
U D
u
U D
U D
u
u
D
u
u
u
D
U D
u
U D
u
u u
u
u
u
u
u
U D
u
u u
u
U D
u
APPENDIX 3.C (Page 2)
Carex fl I lfol ia Nutt.
Carex garber! Fern.
Carex I imosa L.
Carex lollacea L.
Carex media R. Br. ex Richards.
Carex "iileiiii)i='"anacea Hook.
Carex podocarpa c. B. Clarke
Car ex rhynchophysa c •. A. Mey.
Carex saxati I is L.
Carex spp.
ETeOcharls sp.
Eriophorum angustlfol ium Honck.
Erlophorum scheuchzeri Hoppe
Eriophorum vaglnatum L.
Er I ophorum sp.
Scirpus microcarpus Prest.
Trlchophorum caespitosum <L.) Hartm.
Gramlneae (Poaceae)
Agropyron boreale <Turcz.> Drobov
Agropyron canlnum (L.) Beauv.
Agropyron macrourum (Turcz.> Drobov
Agropyron sp.
Agrostls scabra WI lid.
Agrostls sp.
Alopecurus alpinus Sm.
Arctagrostis latifolla (R. Br.) Griseb.
Beckmannia syzlgachne <Steud.) Fern
Calamagrostls canadensis (Michx.> Beauv.
Caiamagrostis pur¥urascens R. Br.
Cinna latlfolla (rev.) Griseb. In Ledeb
~onia lntermedia Vasey
Deschampsia atropurpurea (Wahlenb.l
Scheele**
Deschampsia caestitosa (L.) Beauv.
Festuca altalca rin.
Festuca rubra L. Co I 1.
Hierochloe alptna <Swartz) Roem. & Schult.
Hlerochloe odorata <L.l Wahlenb.
Phleum commutatum Gandoger
Poa alplna L.
Poa arctlca R. Br.
"flO'a pa I ustr Is L.
irlisetum spicatum (L.l Richter
lrldaceae
~ setosa Pel las
Juncaceae
Juncus arctlcus Wi1 ld.
Juncus castaneus Sm.
Juncus drummond I I E. Mey.
Juncus mertenslanus Bong.
Juncus trlglumls L.
Luzula campestrls (L.) DC. ex DC.
& Lam.**
Luzula confusa Lindeb.
Luzula multiflora <Retz.> Lej,
Luzula parviflora (Ehrh.) Desv.
Luzula tundrlcola Gorodk.
Luzula wahlenbergli Rupr.
r-::-'
Thread-leaf sedge u
Sedge D
Shore sedge u
Sedge u
Sedge u
Frag lie sedge u
Short-stalk sedge u
Sedge u
Sedge D
Sedge U D
Spike rush
Tall cottongrass u
White cottongrass u
Tussock cottongrass U D
Cotton grass D
Small-fruit bullrush D
Tufted c I ubrush u
Northern wheatgrass D r:;-
Wheatgrass D
Wheatgrass D
Wheatgrass u
Tickle grass u D
Bent grass u
Mountain foxtai I u
Polargrass u
Slough grass D
Bluejoint U D
Purple reedgrass u
Wood reed D
Timber oatgrass u
Mountain halrgrass u
Tufted hairgrass u D
Fescue grass u
Red fescue u
Alpine holygrass u
Van i I I a grass u D
Timothy u
Alpine bluegrass u
Arctic b I uegrass u
Bluegrass u ,--··-,
Downy oatgrass u D
WII d iris u
Arctic rush U D
Chestnut rush u
Drummond rush u
Mertens rush u
Rush u
Wood rush u
Northern wood rush u
Wood rush u
Smal I-f lowered woodrush u
Tundra woodrush u
Wahlenberg woodrush u
I'""
-
-
-
-
-
APPENDIX 3.C CPage 3)
Lll iaceae
Lloydla serotina (l.) Rchb.
Streptopus amplexlfolius (L.) DC.
Tofieldia coccinea Richards
Tofieldia pusl I Ia (Mlchx.> Pars.
Veratrum vlrlde Ait.
Zygadenus elegans Pursh
Orch I daceae
listera cordata <L.> R. Br.
Platanthera convallarlaefolla
<Fisch.> Lindl.
Platanthera di latata (Purshl Lind I.
Platanthera hyperborea <L.> Lind!.
Potamogetomaceae
Potamogeton epihydrus Rat.
Pota~eton filiformls Pars.
Potamogeton gramineus L.
Potamogeton pertoliatus L.
Potamogeton robbins! I Oakes
Sparganiaceae
Sparganium angustifollum Michx.
Dicotyledoneae
Ara llaceae
Echinopanax horridum <Sm.> Deena.
& Planch.
Betu I aceae***
Alnus crispa (Ait.) Pursh
Alnus slnuata <Reg.) Rydb.
Alnus tenulfolla Nutt.
Alnus sp.
~a glandulosa Michx.
Betu I a nana L.
Betula occidental is Hook.
Betula papyrifera Marsh.
Boraginaceae
Mertensla panlculata (Alt.> G. Don
Myosotls alpestrls F. w. Schmidt
Ca I I I tr I chaceae
Callltriche hermaphroditica L.
Callltriche vernaL.
Campanulaceae
Campanula lasiocarpa Cham.
CaprI to II aceae
llnnaea borealis L.
Sambuons callicarpa
VIburnum edule (Michx.l Rat.
Alp I i fy
Cucumber root
Northern asphodel
Scotch asphode I
Fa I se he I I ebore
Elegant death camas
Twyblade
Northern bog-orchis
White bog-orchis
Northern bog-orchIs
Nutta I I pondweed
F i I i form pondweed
Pondweed
Clasping-leaf pondweed
Robbins pondweed
Narrow-leaved burreed
Devll 1 s club
American green alder
51 tka alder
Thlnleat alder
Alder
Resin birch
Dwarf arctic birch
Water birch
Paper birch
Tall bluebell
Forget-me-not
Water starwort
Vernal water starwort
Mountain harebel I
Twin-flower
Pacific red elder
High bush cranberry
u
U D
u
u u
u
u
u
u
u
u
u
u
u
u
U D I
u
U D
D
u
U D
u
U D
U D I
u
u
u
u
.u
u D
APPENDIX 3.C (Page 4)
Caryophy II aceae
Mlnuartia obtusiloba (Rydb.l House
Moehringia laterifolla (L.l Fenzl
S I I ene acau I Is L.
Stellarla crasslfolla Ehrh.
Stellarla sp.
Wilhelmsla physodes (Fisch.> McNeill
Compositae (Asteraceael
Achillea borealis Bong.
AchIllea s 1 blr lea Ledeb.
Antennaria alpina <L.> Gaertn.
Antennarla monoceghala DC.
Antennaria rosea reene
Arnica amplexicaulis Nutt. ssp. prima
Maguire
Arnica chamlssonis Less. (?l
Arnica friglda c. A. Mey.
Arnica lessingii Greene
Artemisia alaskana Rydb.
Artemisia arctlca Less.
Artemisia tilesii Ledeb.
Aster sibiricus L.
Erigeron acris subsp. polltus (L.>
<E. Fries> Schinz & Keller
Erigeron humilis Graham
Erigeron lonchophyllus Hook.
Erigeron purpuratus Greene
Hieraclum triste Wllld
Petasltes frigldus <L.l Franch.
Petasites sagittatus (Banks> Gray
Petasites sp.
Saussurea angustifolla (Willd.l DC.
Senecio atropurpureus (Ledeb.l Fedtsch.
Senecio lugens Richards.
Senecio sheldonensis Pors.
Senecio triangularis Hook
Senecio sp.
Solidago multiradiata A it.
Taraxacum sp.
Cornaceae sp.
Cornus canadensis L.
Crassu laceae
Sedum ~ <L. l Scop.
Cruclferae (Brasslcaceal
Oraba aurea Vahl
car:damTri'ebe Ill d I fo I Ia L.
Cardamlne pratensls L.
Cardamlne umbeilata Greene
Draba nival is lt ljebl
Draba steno I oba Ledeb.
~a nudicaulls (L.> Regel
01 a pens I aceae
Dlapensla lapponlca L.
Alpine sandwort
Grove Sandwort
Moss camp I on
Chickweed
Starwort
Merckia
Yarrow
SIberian yarrow
AI pine pussytoes
Pussytoes
Pussytoes
Arnica
Arnica
Arnica
Arnica
A I aska wormwood
Wormwood
Wormwood
Siberian aster
Fleabane
Flea bane daIsy
Oa isy
Flea bane
Wooly hawkweed
Arctic sweet coltsfoot
Arrowleaf sweet coltsfoot
Sweet coltsfoot
Saussurea
Ragwort
Ragwort
Sheldon groundsel
Ragwort
Ragwort
Northern goldenrod
Dandelion
Bunch berry
Rose root
Draba
Alpine blttercress
Cuckoo f I ower
Blttercress
Rockcress
Rockcress
Parry a
Dlapensla
u
u
u
u
u 0
U D
u
u
u
u
D
u u
u
u
U D
U D
I
u
D
u
u
u
0
u
u
u
u
U D
u
U D I
u
u u
u u u
u
r-~-'
r -~
-
-
-
-
-
,. .....
APPENDIX 3.C (Page 5)
Droseraceae
Drosera rotundlfolia L.
E I aeagn aceae
Shepherdia canadensis (L.> Nutt.
Empetraceae
Empetrum nlgrum L.
Ericaceae
Andromeda pollfolia L.
Arctostaphylos alplna (L.> Spreng.
Arctostaphylos rubra (Rehd. & Wilson> Fern.
Arctostaphylos uva-ursl (L.> Spreng.
Cassiope tetragona (L.> o. Don
Ledum decumbens (Alt.> Smal I***
Ledum groenlandlcum Oeder
Ledum sp.
l:Oi'Seleuria procumbens (L.> Desv.
Menziesia ferruglnea Sm.
Oxycoccus microcarpus Turcz.
Rhododendron lapponlcum (L.> Wah'lenb.
Vaccinlum caespltosum Michx.
Vacclnlum uliglnosum L.
Vacclnlum vltls-ldaea L.
Vaccinium sp.
Fumarl aceae
Corydalis pauciflora (Staph.> Pers.
Gentlanaceae
Gentiana glauca Pall.
Gentiana propinqua Richards.
Menyanthes trifoliata L.
Swertia perennls L.
Geran iaceae
Geranium erlanthum DC.
Haloragaceae
Hlppuris vulgaris L.
Legumlnosae (Fabaceae)
Astragalus aboriglnum Richards.
Astragalus alplnus L.**
Astragalus umbellatus Bunge
Hedysarum alpinum L.
Luplnus arctlcus s. Wats.
Oxytropls campestrls (L.> DC.
Oxytrop Is hudde I son II Pros I I d
Oxytropls maydelliana Trautv.
Oxytropls nlgrescens (Pall.> Fisch.
Oxytropls vlsclda Nutt.
Sundew
Soap berry
Crowberry
Bog rosemary
Alpine bearberry
Red-fruit bearberry
Bearberry
Four-angle mountain
heather
Northern Labrador tea
Labrador tea
Labrador tea
A I p I ne aza I ea
Menzies! a
Swamp cranberry
Lap land rosebay
Dwarf blueberry
Bog b I ueberry
Mountain cranberry
Blueberry
Few-flowered coryda I is
Glaucous gentian
Gentian
Buckbean
Gentian
Northern geranium
Common ma rest a II
Mi I k-vetch
Milk-vetch
Mi I k-vetch
A I p I ne sweet-vetch
Arctic lupine
Field oxytrope
Huddelson oxytrope
Mayde! I oxytrope
Blackish oxytrope
VIscid oxytrope
U D I
u
u
u
u
u
u
u
u
D
u
U D
u
u
U D
u
u
u
U D
u
u
u
u
U D
u
U D
u
u
u
u
u
D
APPENDIX 3.C (Page 6)
Lentibularlaceae
PinQuicula vi I losa L.
Utricularla vulgaris L.
Myr I caceae
Myrica~ L.
Nymphaeaceae
Nuphar polysepalum Engelm.
Onagraceae
Clrcaea alpina L.
Epilobium angustifol ium L.
Epilobium latifol ium L.
Epllobium palustre L.
Orobanchaceae
Boschniakia rosslca (Cham. & Schlecht.
Fedtsch.
Po I emon I aceae
Polemonlum acutiflorum Wi I ld.
Polygonaceae
Oxyria digyna (L.l Hi II
Polygonum bistorta L.
Polygonum viviparum L.
Rumex arcticus Trautv.
Rumex sp.
Portulacaceae
Claytonia sarmentosa c. A. Mey.
Primulaceae
Androsace chamaejasme Hult.
Dodecatheon frigldum Cham. & Schlecht.
Primula cuneifol ia Ledeb.
Trlentalis europaea L.
Pyrolaceae
Moneses uniflora (L.l Gray
Pyrola asarifolia Michx.
Pyrola grandiflora Radius
Pyrola minor L.
Pyrola secunda L.
Pyrola sp.
Ranunculaceae
Aconitum delphinifollum DC.
Actaea rubra (Alt.) Wi I I d.
Anemone narcissiflora L.
Anemone parviflora Michx.
Anemone richardson! I Hook
Anemone sp.
Caltha leptosepala oc.
Ha l ry butterwort
Common bladderwort
Sweet gale
Yellow pond Illy
Enchanter's nightshade
Fireweed
Dwarf f i reweed
Swamp willow-herb
Poque
Jacob's ladder
Mountain sorrel
Meadow bistort
Alpine bistort
Arctic dock
Dock
Spring-beauty
Androsace
Northern shooting star
Wedge-leaf primrose
Arctic starflower
Single delight
Liverleaf wintergreen
Large-flower wintergreen
Lesser wintergreen
One-sided wintergreen
Wintergreen
Monkshood
Baneberry
Anemone
Northern anemone
Anemone
Anemone
Mountain marsh-marigold
u
u
U D I
u
D
u 0
u 0
u
U D I
U D I
u
u
u
u
u
u
u
u
U D
U D
D
u
u
U D
u
D
u
u
U D
u
-
-
-
-
-
-
-
APPENDIX 3.C (Page 7)
Delphinium glaucum s. Wats
Ranunculus confervoides <E. Fries) E. Fries
Ranuncu I us macoun i 1 BrItt. (may be
B.!_ paclflcus or something simi larl
Ranunculus nlvalls L.
Ranunculus occldentalls Nutt.
Ranunculus pygmaeus Wahlenb.
Ranunculus sp.
Thallctrum alpinum L.
Thallctrum sparslflorum Turcz.
Rosaceae
~s drummond! I Richards.
~ integrlfolla M. Vahl.
~ octopeta I a L.
~macrophyllum Wild.
Geum rossli (R. Br.> Ser.
~kea pectinata (Purshl Ktze.
Potent! I Ia biflora WI lid.
Potentilla fruticosa L.
Potent! I Ia hyparctlca Matte
Potentil Ia palustrls (L.l Scop.
Rosa acicularis Lindt.
Rubus arcticus L.
Rubus chamaemorus L.
Rubus idaeus l.
Rubus pedatus Sm.
Rubus sp.
~lsorba stipulata Rat.
Sibbaldia procumbens L.
Sorbus scopulina Greene
Spiraea beauverdlana Schneid.
Rublaceae
Ga I ium borea le L.
Gallum trifldum L.
Gallum triflorum Michx.
Sa II caceae***
Populus balsamifera L.
Populus tremuloldes Mlchx.
Salix alaxensis <Anderss.l Cov.
Salix arbusculoides Anderss.
SafTX a ret I ca Pa I I.
Sa I I x bare I ay 1 Anderss.
Sa I ix brachycarpa Nutt.
Salix tuscescens Anderss.
Salix glauca l.
Salix lanata L. ssp. richardson!!
~ok) A. Skwortz.
Salix monticola Bebb
Salix novae-angl iae Anderss.
Sa I i x ph I ebophy I I a Anderss.
Salix planltol ia Pursh ssp. planifolla
Salix planlfolla Pursh ssp. pulchra
--rctlam.) Argus
Salix polaris Wahlenb.
~ reticulata L.
Salix rotundifolia Trautv.
Salix scouleriana Barratt
Salix sp.
Larkspur
Water crowfoot
Macoun buttercup
Snow buttercup
Western buttercup
Pygmy buttercup
Buttercup
u
u u
u
u
u
D
Arctic meadowrue
Few-flower meadowrue U D
Drummond mountaln-avens
Dryas
U D u
White mountain-avens
Avens
Ross avens
Luetkea
u
u
u
u
u
u
Two-flower cinquefoil
Shrubby cinquefoil
Arctic cinquefoi I
Marsh cinquefoil
Prickly rose
Nagoon berry
Cloudberry
U D
U D
U D
u
Raspberry
Five-leaf bramble
Raspberry
U D
u
SItka burnet
S.l bbal di a
u
u
u Western mountain ash
Beauverd spIrea U D
Northern bedstraw
Small bedstraw
Sweet-scented bedstraw
u
u
D
Balsam poplar (or cottonwood) U D
Quaking aspen U
Feltleat willow U D
LIt t I etree w i I I ow U D
Arctic wi I low U
Barclay wi I low U
Barren-ground willow U
A I aska bog w I II ow U D
Grayleaf wit low U
Richardson willow U
Park willow U
Ta II blueberry wi I low U D
Skeletonleat willow U
Planeleaf wit low U
Diamond leaf wit low U
Polar willow U
Netleaf wit low U
Least wi I low U
Scouter wll low U
Willow UD
APPENDIX 3.C <Page 8)
Santalaceae
Geocaulon I ivldum (Richards.> Fern.
Sax! fragaceae
Boyklnia rlchardsonli <Hook.) Gray
Leptarrhena pyrol lfol Ia <D. Don) Ser.
Parnassla palustris L.
Parnassla kotzebue! Cham & Schlecht.
Parnassia sp.
Ribes hudsonlanum Richards.
Ribes laxiflorum Pursh (may be~.
glandulosuml
Ribes trlste Pal 1.
~raga bronchialis L.
Saxifraga davurica Willd.
Saxlfraga foliosa R. Br.
Saxifraga hieracifolia Waidst. & Kit.
Saxlfraga Iyaii II Engler
Saxlfraga oppositifolla L.
Saxltraga punctata L.
Sa xi trag a serpy Ill to I i a Pursh
Saxitraga tricuspldata Rottb.
Scrophularlaceae
Castilleja caudata (Pennell) Rebr.
Mimulus guttatus DC.
Pedlcularls capitata Adams
Pedlcularis kane! Durand
Pedlcularis labradorlca Wirsing
Pedicularis parvitlora J. E. Sm. var.
parvlflora
Pedicularis sudetlca Willd.
Pedicularis verticillata L.
Pedicularis sp.
Veronica americana
Veronica wormskjoldii Roem. & Schult.
Umbel I lterae (Aplaceae)
Angelica Iucida L.
Heracleum lanatum Michx.
Valerianaceae
Valeriana capitata Pal 1.
Vlolaceae
Viola epipsila Ledeb.
~ langsdorttii Fisch.
vroTa bit lora L.
Viola sp.
Nonvascular Plant Species
Lichens
Cetraria cucul lata (Bel 1.) Ach.
Cetraria islandica <L.> Ach.
Cetraria nivalis (L.l Ach.
Cetraria richardsonll Hook.
Cetraria sp.
Cladonla alpestris <L.> Rabenh.
Sanda I wood
Richardson boyklnia
Leather-leaf saxifrage
Northern Grass-of-Parnassus
Kotzebue Grass-of Parnassus
Grass of Parnassus
Northern black currant
Trailing black curr:ant
Red currant
Spotted saxifrage
Saxifrage
Fol lose saxifrage
Hawkweed-leaf saxifrage
Red-stem saxifrage
Purple mountain saxifrage
Brook saxifrage
Thyme-leaf saxifrage
Three-tooth saxifrage
Pale Indian paintbrush
Yellow monkey flower
Capitate lousewort
Kane lousewort
Labrador lousewort
Lousewort
Lousewort
Whorled lousewort
Lousewort
Alpine speedwell
Wild celery
Cow parsnip
Capitate valerian
Marsh violet
Violet
Violet
Violet
u
u
u
u
u
D
U D
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
u
0
r::--
r···-,
,-"·,
F"'
I
-
-
-I
APPENDIX 3.C (Pege 9)
Cladonla mitis Sandst.
Cladonia rangiferine (L.> Web.
C I a don I e sp.
Dactyllne erctica (Hook.> Nyl.
Haemai"omma sp.
Lobaria I lnlta (Ach.> Rabh.
Neihroma sp.
Pe tlgera·sp.
Rhizocarpon geogrephlcum (L.> DC.
Stereocaulon paschele <l.> Hoffm.
Thamnolia vermlcularls {Sw.) Schaer.
Umblllcarla sp.
Mosses
C llmaclum sp.
Hypnum spp. and other feather mosses
Paludella sguerrose (Hedw.> Brtd.t
Por:rrlchum sp. Ptl~ium crtsta-castrensis (Hedw.> DeNot.
Rhacomltrlum sp.
Sphagnum sp.
ReIndeer moss
Knight's plume
* Vascular plent species nomenclature according to Hulten (l968) except where
noted. Lichen nomenclature according to Thomson (1979). Moss nomenclature
according to Conerd (1979>.
**Nomenclature according to Welsh (1974).
***Nomenclature according to Viereck and Little (1972).
t Nomenclature according to Crum (1976).
u
u u
u
u
u u
u
D
U D
u
u
u
u
u
U D
u
U D
U D
,._
'
-
.....
r-
1
-
r
APPENDIX E30
Preliminary List of Plant Species
Intertie Area
-
-
-
r
-
APPEND I X 3.D
PRELIMINARY LIST OF PLANT SPECIES IDENTIFIED DURING 1981 IN THE
INTERTIE PROJECT AREA (FROM COMMONWEALTH 1982)"
Pter idophyta
Aspidlaceae
Dryopteris di latata subsp. americana
Dryopteris fraQrans
Gymnocarplum dryopteris
Athyriaceae
Matteuccia struthiopteris
Equ i setaceae
Eguisetum sp.
Egulsetum silvaticum L.
Gymnospermae
Cupressaceae
Juniperus communis
Pinaceae
Picea glauca
Picea mariana
Monocotyledoneae
Cyperaceae
Carex spp.
EriOj)horum spp.
Gramineae
Calamagrostls canadensis
lr idaceae
~setosa
Shield fern
Fragrant shield-fern
Oak-fern
Ostrich fern
Horsetai I
Woodland horsetai I
Common juniper
White spruce
Black spruce
Sedge
Cotton grass
Bluejoint
Wild Flag
APPENDIX 3.D: (Page 2)
Monocotyledoneae (Cont 1 dl
Lillaceae
Lloydia serotina
Streptopus amplexifolius
Tofieldla pusl I Ia
Veratrum vi ride subsp. eschscholtzi I
Zygadenus elegans
Orchidaceae
Llstera cordata
Platanthera hyperborea
DIcotyledoneae
Ara I I aceae
Oplopanax horrldum
Betu laceae
A I nus cr i spa
Alnus sinuata
~a glandulosa
Betu Ia nana
Betula papyrifera
Boraginaceae
Mertensia paniculata
Campanul aceae
Campanula Jasiocarpa
Capri to Jlaceae
Linnaea boreal is
Sambucus ca Ill carpa
Viburnum edu le
Caryophy I I aceae
Stellarla crassifolla
Moehringia laterlflora
AI p Illy
Twisted-stalk
Scotch asphodel
False hellebore
White camas
Twayb I ade
Bog orchIs
Devi I 's Club
American green alder
Sitka alder
Resin birch.
Dwarf arctic birch
Paper birch
Bluebell
Bellflower
Twin-flower
Pacific red elder
HIgh bush cranberry
Chickweed
Grove sandwort
r:---
r<
-
....
I
I
APPENDIX 3.D: (Page 3)
Dicotyledoneae (Cont 1 d)
Composltae
Arnica trlglda
Artemisia arctica subsp. arctlca
Artemisia tilesli subsp. unalaschcensis
Aster slblrlcus
Erigeron acris subsp. polltus
E. purpuratus
~tasltes trlgidus
Saussurea angustltolla
S·eneclo sp.
Senecl o I ugens
Senecio triangularis
Cornaceae
Cornus canadensis
Crassu I aceae
Sedum~
Cruel ferae
Draba aurea
Pa"'T'Ya ni:idlcau I I s
Diapensiaceae
Dlapensia lapponica
Droseraceae
Drosera rotunditolia
E laeagnaceae
Shepherdia canadensis
Empetraceae
Empetrum nlgrum
Arnica
Wormwood
Wormwood
Siberian aster
Fleabane
Flea bane
A ret i c sweet
co Its toot
Saussurea
Ragwort
Ragwort
Groundsel
Bunchberry
Roseroot
Rock cress
Parrya
Diapensla
Sundew
Butta loberry
Crowberry
APPEND I X 3.D: (Page 4)
Dicotyledoneae (Cont 1 d)
Erlcaceae
Arctostaphylos alplna
Arctostaphylos rubra
Arctostaphylos uva-ursi
Casslope tetragona
Ledum decumbens
Ledum groenlandicum
~leuria procumbens
Menziesfa ferruglnea
Rhododendron lapponicum
Vaccinium uliginosum
Vaccinlum vitis-idaea
Fumariaceae
Corydalis pauclflora
Gentianaceae
Menyanthes trlfoliata
Swertia perennis
Geraniaceae
Geranium erianthum
Leguminosae
Hedysarum alpinum subsp. americanum
Lupinus arcticus
Oxytropis nigrescens
Myricaceae
Myrica~
Onagraceae
Ep I lobium angustlfollum
Epiloblum latlfollum
Orobanchaceae
Boschnlakia rossica
Alpine bearberry
Red-fruit bearberry
Bearberry
Four angle mountain
heather
Northern Labrador
tea
Labrador tea
Alpine azalea
Rusty menzies! a
Lap I and rose bay
Bog b I ueberry
Mountain cranberry
Few-flowered
corydalis
Buckbean
Gentian
Cranesbi II
Alpine-sweet-vetch
Arctic lupine
Blackish oxytrope
Fireweed
River beauty
Poque
-
-
-
-
-
APPENDIX 3eD: {Page 5)
Dlcetyledoneae (Cont.>
P.o I emon I aceae
Polemonlum acutlflorum
Polygonaceae
Oxyria dlgnya
Polygonum vlvlparum
Rumex arct I cus
Portulacaceae
Claytonla sarmentosa
Pr I mu I aceae
Androsace chamaejasme subsp. lehmannlana
Dodecatheon frlgldum
Trientalls europaea subsp. arctlca
Pyrolaceae
Pyroia sp.
Ranunculaceae
Acon.ltum delphlnl folium
subsp. delphinlfollum
Actaea rubra
Anemone narcisslflora
Anemone parvlflora
Anemone richardson!!
Caltha leptosepala
Delphinium glaucum
Ranuncu I us sp.
Thallctrum sparsiflorum
Rosaceae
Dryas drummond! I
Dryas iotegrifol Ia
Geum macrophyllum s~bsp. perlnclsum
Geum ross I I
Potentilla fruticosa
Potentilla palustris
Rosa aclcularls
Rubus arcticus
Rubus chamaemorus
Rubus idaeus var. strigosus
Jacob's ladder
Mountain sorrel
A I pine bi stort
Arctic dock
Spring-beauty
Rock jasmine
Northern shooting star
Arctic starflower
Wintergreen
Monkshood
Baneberry
Anemone
Northern anem::>ne
Anemone
Mountain marsh-marigold
Larkspur
Buttercup
Few-flower meadowrue
Drummond mountaln-avens
WhIte mounta.i n avens
Avens
Ross avens
Bush cinquefoil
Marsh f I vef I nger
Prickley rose
Nagoon-berry
Cloudberry
Raspberry
APPENDIX 3.0: (Page 6)
D l coty I edoneae (Cont.>
Rosaceae (Cont.)
Rubus pedatus
Sangulsorba stipulate
Sorbus scopullna
Spiraea beauverdiana
Rublaceae
Gal fum boreale
Ga I fum sp.
Sa I icaceae
Populus balsamifera
Populus tremuloides
Salix
Sax I tragaceae
Parnassia palustrls subsp. neogaea
P. kotzebue!
R i bes tr i ste
Saxifrage oppositlfolia
Saxifrage tricuspidate
Scrophularlaceae
Castilleja sp.
Mimulus guttatus
Pedlcularis sp.
Pedlcularis kanel
Pedicularis labradorlca
Veronica americana
Umbel I i ferae
Heracleum lanatum
Va ler ianaceae
Valerlana capltata
Violaceae
VIola eplpsi Ia subsp. repens
Viola biflora
Five-leaf bramble
Sitka burnet
Greene mountain-ash
Beauverd spirea
Northern bedstraw
Bedstraw
Balsam poplar
Quakl ng aspen
Wi I low
Northern grass-of-
Parnassus
Grass-of-Parnassus
Red currant
Purple mountain
saxifrage
Three-tooth saxifrage
Indian paintbrush
Yellow monkey flower
Lousewort
Kane I ousewort
Labrador· lousewort
Brook I ime
Cow parsnip
Capitate valerlan
Marsh violet
Violet
,..---,
APPENDIX E3E
Status, Habitat Use and Relative Abundance
of Bird Species in the Middle Susitna Basin
-
APPENDIX 3.E: STATUS, HABITAT USE AND RELATIVE ABUNDANCE
OF BIRD SPECIES IN THE MIDDLE SUSITNA BASIN
,.... (Adapted from Kessel et al. 1982a)
!
Status 1 Main Relative ,.... S~ecles Habitats Abundance 2
Common loon B lakes U-sp, F; FC-S
Ga v I a J.!!!!!!!!:..
!"""'
I Arctic loon B? lakes U-sp, s
Gavla arctlca
Red-throated loon B? lakes, rivers u-sp, s
""""' Gavl a stell ata
Red-necked grebe B lakes u
Podlceps grlsegena ,....
Horned grebe B lakes u
Podice~s aurltus
Whistling swan T lakes u-sp, F -Cygnus columblanus
Trumpeter swan B lakes U-sp, F, FC-S
Cygnus buccinator -Canada goose T lakes, rivers U-sp, F
Branta canadensis
White fronted goose T lakes U-sp
Anser alblfrons
Snow goose T lakes U-sp
Chen caerulescens
Ma liard B lakes, rivers C-sp, FC-S,F
Anas platyrhynchos
Gadwall T, s lakes R-sp, s -Anas strepera
Pintail B lakes C-sp, FC-S, U-F
Anas acuta -Green-winged teal B lakes FC-sp, S, U-F
Anas crecca carollnensls
B I ue-w I nged tea I T lakes R-sp, F -Anas dlscors
American wigeon B lakes FC
Anas americana
Northern shoveler B lakes u
Anas clypeata
Redhead T lakes U-sp
~ Aythya americana
Ring-necked duck T lakes R-sp, F
Aythya co II ar is
-
,~
APPENDIX 3.E (Page 2l
Status 1 Main Relative
Seecies Habitats Abundance2
Canvasback T lakes U-sp
Aythya val lsineria
Greater scaup B lakes C-sp, F
Aythya mar I I a
Lesser scaup B lakes FC-S
Aythya aft In is
Common goldeneye B lakes, rivers FC-sp, F, u-s
Bucephala clangula
Barrow's goldeneye B lakes, rivers
Bucephala islandlca
Buff I ahead T lakes U-sp, FC-F
Buceehala albeola
Oldsquaw B lakes FC-sp, S; U-F
Clangula hyema I Is
Har I equ In duck B rivers FC
Histrlonlcus hlstrlonicus
White-winged scoter T lakes FC
Melanltta deglandi
Surf scoter B lakes u
Melanitta persplcll lata
Black scoter B lakes FC
Melanitta ~
Common merganser B lakes, rivers u
Mergus merganser
Red-breasted merganser B lakes, river.s u
Mergus serrator
Goshawk B deciduous and u
Accipiter gentills mixed forest
Sharp-shinned hawk B? con I ferous and u
Accipiter striatus mixed forest
Red-tailed hawk B coniferous and u
Buteo jamaicensis mixed forest
Golden eagle B clIffs FC
Aquila chrysaetos
Bald eagle B forests, clIffs u
Ha I I aeetus leucocephalus
Marsh hawk B? meadows FC-sp, F; u-s
Circus cyaneus
Osprey T
Pandion haliaetus
lakes R-sp
-
-
APPENDIX 3.E (Page 3)
~
Status 1 Main Relative -S~ecles Habitats Abundance2
Gyrfalcon 8, w c I i tts u
~ rustlcolus
!""" Peregrine fa Icon T1 cliffs 2 records (1974)
Falco ~eregrlnus
Merlin 8? scattered u
Falco columbarlus wood land,
forest edge
American kestrel T open forest R-F
Falco s~arverlus
Spruce grouse 8, w coni fer I ous and FC
Canachltes canadensis mixed forest -Ruffed grouse v forest R
8onasa umbe I I us
WI I low ptarmigan 8, w low shrub land c
...... Lagopus lago~us
Rock ptarmigan 8, W -row , dwarf c
Lagopus mutus shrub land,
block fields -White-tailed ptarmigan 8, W h I gh e I evat ron u
La gop us leucurus dwarf shrub
tundra and
~
block fields
SandhIll crane T wet lands u
Grus canadensis
:-Semlpalmated plover 8 alluvial bars u
Charadrlus semipalmatus
American go I den plover 8 dwarf shrub c
Pluvialis dominica mat and meadow
Whlmbrel 87 dwarf shrub u
Numenlus phaeo~us meadow -Upland sandpiper 8? dwarf shrub R
8artramla _Jonglcauda meadow near
scattered
woodland
,.....,
Greater yellowlegs 8? wet, meadows, u
Tringa melanoleuca lakes and rl ver
shore I i nes
..... Lesser yellowlegs T, s lake and river FC-sp; R-S
Tringa flavi~es shore! ines
So lltary sandpiper 87 scattered wood-u -Tringa sol itarla land, forest
edge near lakes
-
APPENDIX 3.E (Page 4)
Species
Spotted sandpiper
Actitis macularla
Wandering tattler
Heteroscelus lncanus
Turnstone
Arenaria sp.
Northern phalarope
Phalaropus lobatus
Conmon sn I pe
Cape I I a ga I I I nago
Long-billed dowitcher
Limnodromus scolopaceus
Surfblrd
Aphrlza vlrgata
Sanderling
Ca I 1 dr Is a I ba
Semlpalmated sandpiper
Ca I i dr Is pus I I I a
Least sandpiper
Calldrls mlnuti I Ia
Baird's sandpiper
Cal idrls baird! i
Pectoral sandpiper
Calidrls melanotos
Long-tailed jaeger
Stercorarlus longlcaudus
HerrIng gu I I
Larus argentatus
Mew gu II
Larus~
Bonaparte's gull
~phi !adelphia
Arctic tern
Sterna paradisea
Great horned ow I
Bubo vtrglnlanus
Snowy Owl
Nyctea scandlaca
Status 1
B
(B? l, T
T
B?
B
T
B?
T
T, S
B?
B
T
B?
T, S
B, S
B, S
B
B?, W
T
Main
Habitats
alluvial bars
tundra streams
alluvial bar
Reiative2 Abundance
c
u
R
wet meadows FC
with ponds
wet meadows C
lake and river U-sp
shores and bars
dwarf shrub mat R
lake and river R-F
shores and bars
lake and river U-sp, R-S
shores and bars
wet and dwarf FC
shrub meadow
dwarf shrub U
mat
wet meadows, U
pond, lake edges
dwarf shrub FC
mat and meadow
lakes, rivers U
lakes, rivers C
lakes, rivers, U
scattered spruce
woodland
lakes and
lakeshores
FC
open and U
c1osed forest
tundra R
-
....
APPENDIX l.E tPage 5)
Species
Hewk owl
Surn I a .!!.l.!:!.!!.
Short-eared owl
Aslo tlammeus
Boreat owl
Aego If us funereus
Belted kingfisher
Mega eery I e el cyon
Common t I I cker
Coleptes auretus
Hairy woodpecker
Plcoldes vlllosus
Downy woodpecker
Plcoldes pubescens
Black-backed three-toed
woodpecker
Plcotdes arctlcus
Northern three-toed woodpecker
Plcoldes trldectylus
Eastern kingbird
Tyrennus tyrennus
Say's phoebe
Seyorn Is say a
A I der f I ycetcher
Empldonex elnorum
Western wood pewee
Contopus sordldulus
Ollve-slde~-flycetcher
Nuttallornls borealis
-Horned terk
Eremophlle alpestrls
VloJet-green swallow
Techyctnete thalesslne
Tree swell ow
~rldoprocne blcolor
Bank swa I tow
Rlparle rlparle
Ct Iff swallow
Hlrundo pyrrhonote
Status•
8?, w
T, S, (8?)
B? w
B?
B
B, W
B?, W
B?, W
8, W
A
8
8?
B?
8?
B
B?
8?
B
B
Main
Ha~ltats
mixed forest
open habitat
mixed forest
cutbanks,
rl vers
forest edge
Reiatl ve
Abundance 2
u
u
R
u
u
deciduous and U
mixed forest
open deciduous U
and mIxed forest
con I ferous
forest
coniferous
forest
R
u
open shrubland Accidental
upland cliff
medium and
te II shrubs
deciduous
forest
open and
scattered
forest
u
u
R
u
dwarf shrub C-sp, F; FC-S
mat, block
field
riparian FC
ct lffs, rivers
rivers, lakes FC
artbanks, U
rivers
rivers, lakes U, L
APPENDIX 3.E (Page 6)
Status 1 Main Relatl ve
S~ecies Habitats Abundance2
Gray jay 8, w coniferous and c
Perisoreus canadensis mixed forest
81ack-bi lied magpie s, (8?) w open tall u
Plea~ shrubs. scattered
forest
Comrron raven B, w riparian and c
Corvus corax upland cliffs
Black-capped chickadee 8, w deciduous u
Parus atrica~ll Ius forest
Boreal chickadee B, W coniferous FC
Parus hudsonlcus and mixed
forest
Brown creeper B deciduous and u
Certhia faml liarls mixed forest
Dipper 8?W rivers, u
Cinclus mexicanus streams
American robin 8 forest, medium C-sp,S; U-F
Turd us migrator ius and ta II
shrub land
VarIed thrush B forest, tall 0-sp,S; U-F
lxoreus naevlus alder thickets
Hermit thrush B strip forested C-sp,F; U-F r---
Catharus guttatus slopes, ta II-
alder thickets
Swainson 1s thrush B forest FC
Catharus ustulatus
Gray-cheeked thrush B scattered FC
Catharus minlmus spruce, dwarf
spruce, deciduous
forest
Wheatear B b I ock f I e I ds u
Oenanthe oenanthe
Townsend's solitaire B ell ffs u
Myadestes townsend!
Arctic warbler 8 scattered FC
Phy I I oscopus borea I is forest,
medium
shrub land
Golden-crowned kinglet T coniferous and u
Regu I us satra ~a mixed forest
Ruby-crowned kinglet B coniferous c
Regulus calendula forests r~-,,
.....
APPEND I X 3. E (Page 7)
-
Status 1 Main Relatl ve 2
!""" Species Habitats Abundance
Water pipit B dwarf shrub c
Anthus splnoletta mat, block
f feld
Bohemian waxwing B? scattered CTsp,F, u-s
Bombycl I Ia garru I us forest
r-Northern shrike B scattered u
Lan I us excu b I tor forest, ta I I
shrubs
Orange-crowned warbler B scattered u
Vermtvora celata forest, medIum
and tall
shrub land
-Yellow warbler T, S? riparian R
Dendrolca petechia willows
Yellow-rumped warbler B forest c
Oendrolca coronata ,. ..
Blackpoll warbler B ta I I shrubs, FC
Dendrolca striata forest
Northern waterthrush B? tall shrubs FC
Selurus noveboracensls near water
Wi I son's warbler B med I urn shrubs c
W i I son I a pus I I I a with or without
forest overstory
Rusty blackbird T, S? CB?l open con I ferous u
Euphagus carol i nus forest, ta I I -shrubs
Pine grosbeak T, S (B ?l open coniferous u
Plnicola enucleator forest -Gray-crowned rosy fInch B? cliffs, block u
Leucosticte tephrocotis fields
Common redpoll B, W low shrubs, A
Carduells flammea open wood I and
Pine siskin B? mixed forest, u
Carduel is pinus tall shrubs
,.... White-winged crossbi II s, B? coniferous FC
Loxia leucoptera forest
Savannah sparrow B low shrubs A -Passerculus sandwlchensis with gramlnold
ground cover
Dark-eyed junco B open and c
Junco hyema I is closed forest -
APPENDIX 3.E <Page 8)
Species
Tree sparrO'II
Splzella arborea
White-crowned sparrow
Zonotrichia leucophrys
Golden-crowned sparrow
Zonotrichla atricapl I Ia
Fox sparrow
Pas sere II a .1 I I aea
Lincoln's. sparrow
Melospiza I incolnil
Lapland longspur
Calcarlus lapponlcus
Smith's longspur
Calcarius pictus
Snow buntIng
Plectrophenax nivalls
Status 1
B
B
B?
B?
B?
B
B?
B?
Main
Habitats
low shrubs
low and
medium shrubs
low shrubs,
dwarf spruce
Relative
Abundance 2
A
c
u
medium and ta II FC
shrubs with
forest overstory
low and medium U
shrubs near
water
dwarf shrub, A
meadow and mat
dwarf shrub, U
meadow and mat
high elevation FC
c II tts and block
fields
1B breeding confirmed, B? =probably breeds, <B?) =possibly breeds,
T =transient, W = winters, S = summers, A =accidental
2A =abundant, C =common, FC fairly common, U =uncommon, R =rare,
sp =spring, S =summer, F =fall, L = local
-
r
-
-
-
-
APPENDIX E3F
Status and Relative Abundance of Bird Species
in the Lower Susitna Basin
-
-
-
r
I
APPENDIX 3.F: STATUS AND RELATIVE ABUNDANCE OF BIRD SPECIES OBSERVED
ON THE LOWER SUSITNA BASIN DURING GROUND SURVEYS
CONDUCTED JUNE 10 TO JUNE 20, 1982
Species
Arctic loon
Gavla arctica
Red-throated loon
~stet lata
Red-necked grebe
Podlceps grisegena
Double-crested
cormorant
Phalacrocorax aurltus
Whistling swan
Cygnus columbianus
Brant
Branta bernicula
WhIte-fronted goose
Anser a I b I frons
Status 1
M
M
M
M
M
Snow goose <Ml
Chen caeru lescens (M)
Canada goose
Branta canadensis
Green-winged teal
Anas crecca
Mallard
Anas platyrhynchos
Pintai I
Anas acuta
American wigeon
Anas americana
Canvasback
Aythya valislneria
Greater scaup
Aythya mar I I a
M, <PB l
M I (PB)
M, CPB)
M, <PB l
M, <PB l
M
M
Harlequin duck
Hlstrionicus histrlonicus
Surf scoter M.
Melanitta persplcl I lata
Common goldeneye
Bucephala clangula
M, B
Relat lve
Abundance
u
u
u
u
u
u
No. of
lndlviduajs
Observed
0 (2 seen in
May 1982)
6 (2 seen in
May 1982)
0 (5 seen in
May 19811
0 (60 seen near
mouth of rIver
In May 1981 and
420 seen near
mouth of river
in May 19821
0 (2 seen in
May 1981)
<50 (89 seen In
May 1 981 and 51
seen In May 1982)
3 ( 1 seen in
May 1981 an'd 26
seen In May 1982)
Several 2 1s and 3 1 s
(42 seen In
May 1981)
6
<6
Most numerous
surface feeding
duck; seen In
pa I rs a 1 ong rna J n
river and sloughs
a I most every day
a few Individuals in
aerial waterbird surveys
2
6
2
4
APPENDIX 3.F (Page 2)
SpecIes Status 1
Common merganser M, <PB>
Mergus merganser
Red-breasted merganser M
Mergus serator
Bald eagle (Ml, B
Hal laeetus leucocephalus
Sharp-shinned hawk
A~clplter strlatus
Goshawk
Accipter gentills
Red-tailed hawk
Buteo jamaic~nsis
American kestrel
Falco sparverlus
Merlin
Falco columbarius
Sandhill crane
Grus canadensis
(Ml, (PB>
(R >, (PB)
(Ml, ~PB)
(M), (PB)
(M), <PB)
M
Semlpalmated plover (Ml, B
Charadrlus semipalmatus
Greater yellowlegs (M), PB
Tringa melanoleuca
So I I tary sandp I per (M > , (PB)
Tringa solltaria
Spotted sandpiper <M>, B
Actltus macularia
Whlmbrel
Numenlus phaeopus
Comron sn I pe
Capella gall lnago
M
{M) I (PB)
Relative
Abundance
FC
FC
u
u
u
FC
c
FC
No. of
Individuals
Observed
Smal I flocks of up
to 10 seen along
the rna In r l ver;
most numerous
ducks seen in May
and June
a fe.t birds along the
river; ~ess common
than Its congenor
17 act lve nests
seen In riparian
cottonwood stands
Severa I seen
Several seen
A few seen hunting
along rIver
Several heard at a
distance along main
river (27 seen near
mouth of river In
May 1982>
Nests In alluvium
along the river
Seen and heard
foraging along
river
CourtshIp r ltua Is
observed a I ong
r lver
Regularly seen; 5
nests seen along
shores of main
river, sloughs and
feeder streams
Only I observed;
assumed to be late
northbound migrant
Winnowing snipe were
heard and/or seen
along the river
-
-
r
APPENDIX 3.F (Page 3r
Species
Northern phalarope
Phalaropus tobatus
Parasitic jaeger
Stercorarlus parasltlcus
Bonaparte's gut I
~philadelphia
Mew gull
Larus~
Herring gull
Larus argentatus
B I ack-1 egged
kittiwake
Rlssa tridactyla
Arctic tern
Sterna paradlsaea
Great horned ar~l
Bubo vlrginlanus
Short-eared owl
~ flemmeus
Belted kingfisher
Megaceryle alcyon
Downy woodpecker
Picoides pubescens
Hairy woodpecker
Pfcoides villosus
Northern three-toed
woodpecker
Plcoldes trldactylus
Common f I ~cker
Colaptes auratus
Status 1
(M), PB
(M), PB
(M), B
(T)
(M >, B
<R), (PB)
04)
(P8}
(R), (P8)
(Rl, B
(R), <PB>
(M), (PB)
Relat lve
Abundance
FC
FC
c
(R)
FC
u
FC
2
3
No. of
lndlvidua\s
Observed
PaIrs and sma II
groups seen
feeding along meln
rIver and s toughs
7 breeding colonies
of 20 -100 pairs
seen on alluvial
Is lands along
r I ver between
Talkeetna and
mouth of river
130; normally a
pelagic species;
nearest breedIng
colony at Chlslk
I s I and In I ar~er
Cook Inlet
Pairs and small
groups
Tracks seen; signs
found In beach
sand bel r1r1 Be I 1
Is I and lnd i cate
thts owl was
feedIng on dead
eul~chon
Remains of one owl
were found below
Bell Island
Pairs regularly seen
on feeder streams
male observed In
riparian cotton-
wood forest
Seen or heard
regularly
2 seen In mixed
forests along
lower river
A few seen and
heard In rlperlan
cottonwood
APPENDIX E.F (Page 4)
Species Status 1
Alder flycatcher PB
Empidonax alnorum
Tree swallow (Ml, B
Tachycineta bicolor
Violet-green swallow (Ml, (PB)
Tachycineta thalassina
Bankswallow (Ml,B
Riparia riparia
Cliff swallow (Ml, B
Hirundo pyrrhonota
Gray jay (R l , (PB)
Perisoreus canadensis
Black-bi lied magpie (Rl
Pica~
Common raven
Corrus corax
Black-capped
chickadee
Parus atricapil Ius
(R l, ( PB)
(M), B
Brown creeper (M)
Certhia famll iarus
Gray-cheeked
thrush
Catharus mlnlmus
Swalnson 1s thrush
Catharus ustulatus
Hermit thrush
Catharus guttatus
American Robin
Turdus migratorlus
Varied thrush
lxoreus naevlus
Go I den-crowned
kinglet
Regu I us satrapa
(M), B
(M), (8)
(M l' P8
(M), B
(M), B
(Ml
Relative
Abundance
c
FC
u
FC
LC
u
FC
c
c
u
FC
FC
No. of
lndividuajs
Observed
Seen regularly (4th
most numerous
land bird
Seen regularly; 3
nests seen
Smal I numbers seen
Some co I on i es of
30 -50 pal rs
Seen only at
Ta I keetna where
commonly breeds
around bu i I ding
eaves
Very feti seen or
heard
Uncommon but
widely distributed
Seen regu I ar I y
Seen regularly (5th
most numerous
passerine on
census
Seen regularly (7th
most numerous
small landblrdl
Not recorded down-
stream from
Ta I keetna
2 nests observed
Seen regularly (10th
most common
passerine
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APPENDIX 3.F (Page 5)
Species
Ruby-crowned
kinglet
Regulus calendula
Boheml an waxwing
Bombycilla garrulus
Northern shrike
Lanius excubitor
Orange-crow ned
warbler
Vermivora celata
Ye I low warbi er
Dendroica petechia
Ye I low-rumped
warbler
Dendroica coronata
Blackpol I warbler
Dendroica striata
Northern waterthrush
Seiurus noveboracensis
Wi !son's warbler
W I I son i a pus i I I a
Rusty blackbird
Euphagus carolinus
White-winged
crossb I II
Loxia leucoptera
Status 1
(M l, PB
<M>
(M), (PB)
(M l, (PB)
(Ml, B
(M), B
(M), B
<M>, B
(M >, PB
(M), B
(M)
Savannah sparrow (Ml, PB
Passerculus sandwichensis
Fox sparrow
Passarella II iaca
Lincoln's sparrow
Melospiza I incolni I
(M l, B
(M), B
Golden-crowned (Ml, B
sparrow
Zonotrichla atricapilla
Relative
Abundance
FC
u
FC
FC
c
c
c
FC
u
u
u
c
FC
u
No. of
Individuals
Observed
Seen regularly
Fewer than 12 seen
2
Seen regularly
1 nest seen; tall
shrubs
2nd most common
passerIne seen
regu tar I y In
mixed forest,
cottonwood and
tall shrubs
3rd most common
passerine seen
regularly in tall
riparian shrubs,
cottonwood and
mixed forest
Most numerous
passerine seen
regularly In
riparian cotton-
wood and mixed
cottonwood
2
48
1 nest seen
Individual was
heard just above
Be I I Is land
APPENDIX l.F (~age 6)
No. of
Stl!lfus 1 Relat Lve lndlvldul!ljs
S~ecles Abundance Obser-ved
White-cr-owned on. a c 9th most numer-ous
sparr-ow passerIne seen
Zonotr-lchla leuco~hrys regularly In
medium to tall
shr-ub th lckets
and cottonwood
forests on smal I
Islands
Dar-k-eyed Junco (M)' 8 FC
~hyemalls
Co11111on r-edpoll (M) FC
Car-duel is flammea
Pine siskin CM) u A few were heard
Car-duel is~ or seen In
cottonwoods
along river
1 ancludes Information on migration from aerial surveys In May 1981 and 1982.
2 c ) Indicates assessments of status or relative abundance other than those
pr-ovided by the University of A Iaska museum.
3a = breeding confirmed, PB = probably breeds, M = migrant, R = r-esident
4R =rare,_ U= unconvnon, FC = fairly common, C =common, LC = locally common
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APPENDIX E3G
Scientific Names of Manunal Species
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Common Name
Masked Shrew
Dusky Shrew
APPENDIX 3.G:
Northern Water Shrew
Arctic Shrew
Pygmy Shrew
Little Brown Bat
Collared Pika
Snowshoe Hare
Hoary Marmot
Arctic Ground Squirrel
Red Squirrel
Beaver
Northern Red-backed Vole
Meadow Vole
Tundra Vole
Singing Vole
Muskrat
Brown Lemming
Northern Bog Lemming
Porcupine
Be I ukha Whale
Coyote
Wolf
Red Fox
Black Bear
Brown Bear
Marten
Short-tal led Weasel
Least Wease I
Mink
Wolverine
River Otter
lynx
Moose
Caribou
Dall Sheep
SCIENTIFIC NAMES OF MAMMAL SPECIES
FOUND IN THE PROJECT AREA
Scientific Name
Sorex clnereus
Sorex mont I co I us
Sorex pa I ustr Is
Sorex arctlcus
M I crosorex ~
Myotls luclfugus
Ochotona collarls
Lepus arnerlcanus
Marmota ca ligata
Spermophl Ius parry! I
Tamlasclurus hudsonicus
Castor canadensis
Clethrlonomys rutl Ius
Microtus pennsylvanlcus
Microtus oeconomus
Microtus miurus
Ondatra zibethica
Lemmus siblricus
Synaptomys borealis
Erethlzon dorsatum
Delphlnapterus leucas
Canis latrans
Canis~
Vulpes fulva
Ursus americanus
Ursus arctos
Martes americana
Mustela ermlnea
Mustela nival is
Mustela vlson
Gulo .9..!!...!£_
Lutra canadensis
Lynx canadensis
Alces alces
Rangifer tarandus
Ovis~
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APPENDIX E3H
Methods Used to Determine Moose Browse Utilization
and Carrying Capacity within the Middle Susitna Basin
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APPENDIX 3.H
METHODS USED TO DETERMINE MOOSE BROWSE UTILIZATION
AND CARRYING CAPACITY WITHIN THE MIDDLE SUSlTNA BASIN
Moose habitat research was conducted in the middle basiri in 1982 by the
Plant Ecology Team of the University of Alaska Agricultural Experimen-
tal Station. The objective of the moose browse study was to estimate.
the avail abi 1 i ty of browse and herbaceous plants for each vegetation
type.
Field Methods
Sites sampled were randomly selected using a grid overlay on a vegeta-
tion map of the area within about 5 mi of potential dam impoundments.
However, eight sites were lo·cated mid-slope at the phenology study
sites on both north and south-facing slopes to insure that some samples
occurred in the immediate impoundment area. Sites were classified to
Levels IV and V of Viereck et al. (1982), when possible. Forty-seven
stands were examined from July through August 1982. Some habitat types
were sampled more intensively than others, based on their importance to
moose and/or 1 and area occupied by that type •
At each sample site, three parallel 50-m line transects were estab-
1 ished, approximately 10 to 20m apart. Every 10m along each transect
line, a plot (1 x 0.5 m) was located. Percent cover of each plant
species, including trees less than 1.13 m in height, was estimated in
each 0.5 m2 plot. All grasses, Carex, forbs, and the current annual
growth of tall shrubs were clipped 1n each plot. Clipped samples were
bagged, oven-dried at 60°C for 48 hours, then weighed~ Kg/ha of grami-
noids, forbs, and leaves and twigs of moose browse species were cal cu-
lated by multiplying the biomass (in grams) from 0.5 m2 plots by 20.
A circular plot with a 5 m radius was established every 10m along each
transect line. This plot was divided into 4 even-sized quadrants.
Within each quadrant, the distance to the nearest stem of each browse
species represented within a quadrant was measured. The basal diameter
and average height of that stem was measured and the number of twigs,
above 50 em (19 inches), was counted and noted as to evidence of recent
browsing. A twig was defined as a branch that had a diameter equal to
the estimated diameter at point of browsing for that species. The
average diameter at point of browsing for each species was estimated by
randomly measuring twigs that were browsed at a nl.Dllber of sites over
the entire study area. Percent utilization was determined by dividing
the number of browsed twigs by the total number of twigs ab<;>ve 50 em.
At each site, 25 twigs from each browse species present were also
randomly harvested at the average point of browsing. These twigs
provided an estimate of biomass removed when the shrubs had been
browsed by moose.
Carrying Capacity
A preliminary estimate of moose carrying capacity was calculated from
the browse biomass estimates obtained in Sllllmer 1982. A ~imulation
modeling approach is being developed to calculate carrying capacity and
project impacts on moose based on available energy and nitrogen, snow-
fall, and other important inputs, .and therefore, a greatly refined
estimate of carrying capacity will eventually be available. The preli-
minary estimate shown in Table E.3.92 is based on the following data
and assumptions:
1. Browse biomass estim:ates for each Level III vegetation type are
representative of all other similar stands throughout the middle
basin (e.g., all open conifer forest stands have the same biomass
as those sampled).
2. The vegetation maps produced in 1980-81 accurately portray the
vegetative cover of the middle basin (vegetation is being remapped
now that low-level photography is available).
3. Moose in winter eat only the current annual growth of twigs of the
following species: Richardson willow, grayleaf willow, diamondleaf
willow, Sitka alder, and resin birch. The calculations assume that
none of the twigs are consumed in summer, and that snow does not
make any twigs unavailable. Both of these assumptions are in fact
false; however, the analysis is also biased in the other direction
because moose can consume more than the current annual growth of
twigs, eat other browse species in winter, and consume some leaves
and forbs available in winter.
4. A moose in winter requires 5.0 kg dry weight of browse per day
(Gasaway and Coady 1974). This value takes into account the
composition and digestibility of the diets of moose in interior
Alaska.
5. Areas mapped as closed conifer forest, closed birch forest, closed
mixed forest, tall shrub (mostly alder), and tundra, contain no
moose browse avail able to moose in winter. Except for tundra and
tall shrub types, these types cover only a small proportion of the
middle basin, and closed forest stands support low browse biomass.
Little, if any browse is available to moose in tundra areas and
tall shrubs are mostly alder, which is not a preferred browse
species.
6. The number of moose days the areas can support is calculated for
the Watana impoundment and adjacent village and borrow sites and
for the entire watershed upstream of Gal d Creek. The number of
winter residents these areas can support is calculated assuming
that winter 1 asts for 180 days and food requirements are the same
throughout that period, and that moose do not move into or out of
the study areas.
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APPENDIX E3I
Explanation and Justification of Artificial Nest Mitigation
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APPENDIX 3.!
EXPLANATION AND JUSTIF !CATION OF ARTIFICIAL NEST MITIGATION
The concept of modifying cliff-nesting and tree-nesting habitat to
provide raptors new nesting locations and nest sites appears to offer
an effective and feasible means of compensating for losses of nesting
habitat incurred in the upper Susitna River basin as a result of con-
struction and operation of the Susitna Hydroelectric Project. A major
advantage of this type of compensation is that it allows actual mitiga-
tion of losses in the same area where they were incurred, rather than
on distant 1 ands or by some form of out-of-kind compensation. The con-
cept relies on the fact that raptors are one of the few groups of birds
that are limited by availability of nesting locations and nest sites in
most regions, rather than food (see Newton 1979). Many methods and
techniques have proven successful, and additional techniques and
methods are being developed and tested (e.g. 01 endorff et al. 1980).
Some successful applications and experiments involving several raptor
species are given below.
1. Nest sites ("pot-hole" type) have been successfully provided
for prairie falcons (E. Mexicanus) in cliffs that lacked
natural cavities in Alberta (Fyfe and Armbruster 1977).
Originally, some holes were blasted out of the rock, but it
became more effective to locate soft spots in the sandstone
and dig them by hand. The program has provided about 200 new
cavities for nesting prairie falcons, about 25 percent of
which have been used successfully, and has increased the
number of prairie falcons in several Alberta river drainages.
2. A ledge was excavated in December 1979 on a cliff in Califor-
nia that was rated as a potential peregrine falcon nesting
location, but had no history of previous use. Four months
later, early in the 1980 nesting season, a female peregrine
occupied it. She laid eggs on the new ledge and was observed
incubating them (see Olendorff et al. 1980).
3. Because nest sites at some peregrine nesting cliffs in the
Massif Central of Europe were accessible to predators (gen-
ets), a new artificial, but natural appearing, ledge was con-
structed in a rock face near the top of one of the nesting
locations. It was readily accepted by a pair of peregrines
(Cugnasse 1980).
4. The nesting ledge fell off an abandoned peregrine falcon nest-
ing cliff in California. A steel and lightweight metal ledge
was fabricated, artistically modified to look relatively natu-
ral, and installed on the rock face in four days time. The
following year a pair of prairie falcons accepted the ledge
and successfully fledged young from it (Boyce et al. 1980).
5. A golden eagle tree-nest was blown down. The nesting loca-
tion was not occupied by eagles the following year and later
that summer an artificial nest was built. Golden eagles
nested at it the next year (Craig and Anderson in Call 1979).
6. A nest site designed for gyrfalcons was constructed on a cliff
in northern Europe. It was used by gyrfalcons the following
year (see Olendorff et al. 1980).
7. A cliff used by gyrfalcons was found in 1968 on the Seward
Peninsula, Alaska. The cliff had only one useable 1 edge on
it, although an excellent potential pot-hole site was also
present. The pot-hole site was unuseable because the floor
lacked detritus and soil for scraping in, and it also sloped
steeply to the rear of the cavity. Two years later (1970) the
original ledge had become unstable and was in danger of fall-
ing off the cliff. At the completion of the 1970 breeding
season, material (sand, dirt and fine gravel) was placed in
the pot-hole cavity to level the floor. A rim was constructed
of wired-together sticks and in turn wired to the rock (the
rim simulated the remains of a rough-legged hawk nest, often
used by gyrfalcons). The falcons scraped in the new site the
following year {1974), but still used the old, unstable ledge
(D.G. Roseneau and W. Walker II, unpubl. data). In later
years the original 1 edge became very del api dated and was not
used by the gyrfalcons, but the modified site was (W.R. Tilton
pers. comm.).
8. A golden eagle nest in a tree in Wyoming was located on lands
that were to be strip-mined for coal. Through a series of
manipulations involving first providing and then destroying
several artificial platforms and nests, moving a nestling
after it was capab 1 e of thermoregulation, and moving a nest
constructed by the eagles, the nesting pair was successfully
relocated over the course of two breeding seasons to a new
nesting location outside of the coal development area and 2.5
km from the original nesting location (Postovit et al. 1982).
9. An active bald eagle nest was blown down. It was reconstruc-
ted and the two nestlings successfully fledged from it (Dun-
stan and Borth 1970).
10. In two separate attempts several nest boxes were placed out
specifically for· boreal owls near Fairbanks, Alaska. In both
cases several pairs of ~oreal owls readily accepted them, and
in one instance a pair of hawk owls also used one of the boxes
(D.G. Roseneau and W.R. Tilton pers. comm.).
In several cases attempts to provide a variety of artificial
structures have not worked for some species. However, in
virtually all such cases, no attempt was made to provide natural
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appearing nesting locations and natural appearig nesting sites or
nests. Other failures have also clearly involved elements of
design and choice of locations. The failure of an attempt to
provide nest sites for peregrines and gyrfalcons at Sagwon Bluffs,
Alaska (see Olendorff et al. 1980), is more readily explained by
elements of design, an abundance of nearly natural nest sites
relative to the abundance of peregrines and gyrfalcons at that
particular Arctic Slope location, and other factors rather than by
a failure of the technique.
In several instances, successful experiments and applications have
involved only one or two pairs of some raptor species. At pre-
sent, 1 imited numbers of experiments and applications are more a
result of lack of opportunity and support than a lack of suffici-
ent knowledge, methods and techniques. Successful app 1 i cations
and experiments involving many raptor species clearly suggest that
chances of success of such compensatory measures in the Sus itna
River drainage are high for the species i nvo 1 ved, especially if
proper planning, appropriate design, and expertise are employed.
Chances of success and ultimate overall effectiveness can be in-
creased further by modifying a larger number of a variety of
currently unused potential nesting locations than are lost, in-
cluding those remaining along the impoundment edge above maximum
reservoir level, those in the nearby vicinity of the project, and
those that may occur in other more distant areas of the middle and
upper Susitna River basins. This would allow pairs of raptors a
greater variety of choices. Only appropriate numbers of pairs of
each species have accepted and established themselves at the arti-
ficially modified locations. Excess locations can be remodified
to prevent their use, and thereby achieve a balanced state.
Methods and techniques u'sed to provide compensatory raptor nesting
locations and nest sites will be individually tailored to each
species and may vary slightly as each particular situation dic-
tates. Basic methods employed will center around modifying micro-
relief of existing but currently unuseable cliffs near the project
areas and in some outlying areas of the middle and upper basins,
and providing natural-appearing artificial nests where appropriate
(cliff-nesters, especially golden eagles); modifying selected
tree-cover and supplying natural appearing artificial nests where
appropriate (tree-nesters, especially bald eagles}; and providing
both natural appearing and less modified nesting boxes in appro-
priate habitat (cavity nesters, including boreal owls, hawk owls
and kestrels). Artificial platforms with artificial but natural
appearing stick nests that can be installed on selected transmis-
sion towers will also be experimented with (especially for golden
eagles).
Compensatory measures will take into account such factors as slope,
aspect, height, overlook, distance to alternates, and overall dis-
tribution of n~sting locations, accessability to predators, drain-
age, sun shadow, and vegetation types and size used to construct
nests as applicable to each species. All compensatory measures
will be monitored and modifications made as necessary. Detailed
accounts of methods, techniques and results will be kept to ensure
maximum scientific value for further evaluation and use.
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APPENDIX E3J
Personal Communications
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APPEND I X 3. J
PERSONAL COMMUNICATIONS
M. Amaral. 1982. U.S. Fish and Wildlife Service •
R. Archibald. 1982. Yukon Game Branch, Whitehorse
W. Ba 11 a rd. 1982. Alaska Department of Fish and Game
F. Banfield. 1982. Rangifer Associates, St. Catherines, Ontario
R. Bonar. 1982. British Columbia Hydro Revelstoke, B.C.
s. Buskirk. 1982. Institute of Arctic Biology, University of Alaska
D. Calkins. 1982. Alaska Department of Fish and Game
K. Child. 1982. British Columbia Wildlife Branch, Prince George,
B.C.
B. Cooper. 1982. University of Alaska Museum
L. Duncan. 1982. Acres American Incorporated
D. G·i bson. 1982. University of Alaska Museum
P. Gipson. 1982. Alaska Cooperative Wildlife Research Unit,
University of Alaska
J. Green. 1982. LGL Environmental Research Associates, Ltd.,
Edmonton, Alberta
F. Harper. 1982. British Columbia Wildlife Branch, Fort St. John,
B.C.
D. Herter. 1982. LGL Alaska Environmental Research Associates, Ltd.,
Fairbanks
T. Hobgood. 1982. Institute of Arctic Biology, University of Alaska
(cited in Kessel et al. 1982a).
J. Ireland. 1982. Resident of Murder Lake (cited in Kessel et al.
1982a).
B. Kessel. 1982 and 1983. Universi~y of Alaska Museum
J. King. 1982. u.s. Fish and Wildlife Service
H. Larsen. 1981. Trapper and Alaska Railroad Agent, Gold Creek (cited
in Gipson et al. 1982)
T. Lavender. 1982. Acres Consulting Services, Ltd., Niagara Falls,
Ontario
S. MacDonald. 1982. University of Alaska Museum
A. Magoun. 1982. Institute of Arctic Biology, University of Alaska
J. McBeath. 1982. University of Alaska Agricultural Experiment
Station, Palmer (cited in Kessel et al. 1982a).
J. McKendrick. 1982. University of Alaska Agricultural Experiment
Station, Pa 1 mer
S. Miller. 1982. Alaska Department of Fish and Game
R. Modafferi. 1982. Alaska Department of Fish and Game
R. Movald. 1982. British Columbia Hydro, Hudson Hope, B.C.
E. Powell. 1982. Trapper and Lodge Manager, Stephan Lake Lodge
R. Peterson. 1982. University of Alaska
K. Pitcher. 1982. Alaska Department of Fish and Game
E. Powell. 1982. (cited in Kessel et al. 1982a)
R. Rausch. 1982. Juneau (cited in Kessel et al. 1982a)
W. Regelin. 1982. Alaska Department of Fish and Game
D. Roseneau. 1982. LGL Alaska Environemntal Research Associates,
Ltd., Fairbanks
R. Roullier. 1981. Gold Creek Resident (cited in Gipson et al. 1982)
A. ,Springer. 1982. Falco Enterprises, Fairbanks
N. Thomas. 1982. Conservation Officer, MacKenzie, B.C.
R. Tobey. 1982. Alaska Department of Fish and Game
D. Wier. 1982. Raptor Biologist
D. Wilson. 1981. Fur Dealer, Copper Center (cited in Gipson et al.
1982)
J. Woolington. 1981. Institute of Arctic Biology, University of
Alaska
M. Wrabetz and R. Ward. 1982. U.S. Bureau of Land Management.
Anchorage, Alaska
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GLOSSARY
Accipiter-a member of the family accipitridae, which includes
kites, hawks, and eagles
Adipose fin-a small, thick, posterior dorsal fin containing much
fatty matter, typical of salmoni d fish
Albedo-the percentage of light reflected from a surface
Alevins-newly hatched salmon still attached to the yolk sac
Alpine tundra-plant communities which occur above timberline.
Vegetation is low and matlike and includes a high proportion of
grasses and sedges
Anadromous-an organism that ascends freshwater rivers from the
ocean in order to breed
Aspect -appearance, composition, or inferred environmental implica-
tion of a rock body. Also a particylar compass direction
Aufei s - a sheet of i ce formed on a ri ver p 1 ai n when shoa 1 s freeze or
are dammed so that water spreads over the floodplain and freezes
Bankfill stage-that river stage which fills the river banks up to
the shoreline vegetation, typical of mean annual flood
Browse -leaves, shoots, and twigs of shrubs and trees utili zed as
food
Calcareous-growing on limestone or soils high in lime
Calciphilic-having a tendency to grow in soils rich in calcium or
limestone
Closed forest-forested areas in which the overstory prevents most
of the sunlight from reaching the ground
Coniferous-plants which are cone bearing and nondeciduous, such as
pines and spruce
Coregonid-member of the whitefish family Coregonidae, related to
the salmonids, has a rayless adipose fin
Decadent -decaying or declining in vi gar
Deciduous -ref erri ng to p 1 ants whi ch shed t hei r 1 eaves at a c ert ai n
season each year
Ecotone-the area where two or more plant communities meet and blend
together
Escapement-the process by which adult anadromous fish migrate from
the ocean to their freshwater spawning sites
Floristics-study of the species composition of vegetation
Frazil ice -ice of sma 11 p 1 ate-1 ike crystals suspended in the flow
Gillnetting-a method of capturing fish by hanging nets in which the
gills of the fish become entangled
Glacial flour-silt and clay sized generally nonplastit particles
derived from glacial grinding
Gley-a dense clay layer often present under waterlogged soils
Ground truthing-the process of conducting onsite field studies to
determine if identification of vegetation cover types from aerial
photographs is correct
Herb-plant such as grasses which have no persistent parts above
ground, as distinct from shrubs and trees
Herbaceous-a plant having the characteristics of an herb
Lentic system-relating to sti 11 water such as lakes and ponds
Lotic system-relating to moving water such as rivers and creeks
Mainstem-the major portion of a river into which tributaries enter
Mesic -referring to site conditions that are intermediate between
wet and dry
Micro-relief-very slight changes in elevation
Milling area -an area in a river or stream where anadromous fish
hold or rest prior to continuing their upstream movements
Mixed forest-area which contains both conifero.us and deciduous
trees
Mosaic-a composite resulting from the joining of separate and
different parts
Mustelids-member of the family mustelidae which includes weasels,
mink, skunk, otter, fish and marten
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Open forest-forested areas in which the spacing of trees and
closure of the canopy is such that the majority of the sunlight
reaches the ground
Parturient -bringing forth or about to bring forth young
Peri-glacial-adjacent to the margins of a glacier
Redd-spawning ground or nest of fish
Seral growth-the process by which any stage of a plant community
which is transitory will eventually reach a climax condition
Smolt -a young salmon approximately two years old
Sub-nivean -underneath the snow
Successional stands-any stage of a plant community which is transi-
tory and wi 11 eventually lead to a climax condition
Taxa -plural of taxon
Taxon -a separate and di sti net group in a formal system of c 1 assi fi-
cation
Thermokarst -settling or caving in of the ground due to melting of
ground ice
Ungulates -hoofed mammals such as deer, caribou, and moose
Vascular -containing vessels which conduct fluid
Xerosere -a plant successional stage originating on a dry site
·~·