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Susitna‐Watana Hydroelectric Project Document
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Title:
River productivity study, Study plan Section 9.8, 2014 Study
Implementation Report. [Main report] SuWa 289
Author(s) – Personal:
Author(s) – Corporate:
R2 Resource Consultants, Inc.
Alaska Cooperative Fish and Wildlife Research Unit, University of Alaska Fairbanks
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November 2015; Study Completion and 2014/2015 Implementation Reports
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Series (ARLIS‐assigned report number):
Susitna-Watana Hydroelectric Project document number 289
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Published by:
[Anchorage : Alaska Energy Authority, 2015]
Date published:
October 2015
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Alaska Energy Authority
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Study plan Section 9.8
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xxvii, 231 pages
(main report only)
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Appendix A and Appendix B
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The full report appears in two separate files--one for the main textual report and one for the
appendices.
All reports in the Susitna‐Watana Hydroelectric Project Document series include an ARLIS‐
produced cover page and an ARLIS‐assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna‐watana/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
River Productivity Study
Study Plan Section 9.8
2014 Study Implementation Report
Prepared for
Alaska Energy Authority
Prepared by
R2 Resource Consultants, Inc.
Alaska Cooperative Fish and Wildlife Research Unit,
University of Alaska Fairbanks
October 2015
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i October 2015
TABLE OF CONTENTS
1. Introduction ........................................................................................................................1
2. Study Objectives.................................................................................................................2
3. Study Area ..........................................................................................................................2
4. Methods and Variances In 2014 .......................................................................................3
4.1. River Productivity Implementation Plan ...........................................................3
4.2. Site Selection .....................................................................................................3
4.2.1. Middle River Stations / Focus Areas ...............................................4
4.2.2. Lower River Station .........................................................................5
4.2.3. Variances ..........................................................................................5
4.3. Characterize the Pre-Project Benthic Macroinvertebrate and Algal
Communities with Regard to Species Composition and Abundance in
the Middle and Lower Susitna River .................................................................6
4.3.1. 2013 Field Collection .......................................................................6
4.3.2. Macroinvertebrate Metrics ...............................................................7
4.4. Estimate Drift of Invertebrates in Selected Habitats within the Middle
and Lower Susitna River to Assess Food Availability to Juvenile and
Resident Fishes ..................................................................................................9
4.4.1. Variances ........................................................................................10
4.5. Conduct a Feasibility Study in 2013 to Evaluate the Suitability of
Using Reference Sites on the Talkeetna River to Monitor Long-term
Project-related Change in Benthic Productivity ..............................................10
4.6. Conduct a Trophic Analysis, Using Trophic Modeling and Stable
Isotope Analysis, to Describe the Food Web Relationships in the
Current Riverine Community within the Middle and Lower Susitna
River .................................................................................................................10
4.6.1. Develop a Trophic Model to Estimate How Environmental
Factors and Food Availability Affect the Growth Rate
Potential of Focal Fish Species under Current and Future
Conditions ......................................................................................10
4.6.2. Conduct Stable Isotope Analysis of Food Web Components
to Help Determine Energy Sources and Pathways in the
Riverine Communities ...................................................................14
4.6.3. Variances ........................................................................................18
4.7. Characterize the Invertebrate Compositions in the Diets of
Representative Fish Species in Relationship to their Source (benthic or
drift component)...............................................................................................18
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii October 2015
4.7.1. Variances ........................................................................................20
4.8. Characterize Organic Matter Resources (e.g., available for
macroinvertebrate consumers) Including Coarse Particulate Organic
Matter, Fine Particulate Organic Matter, and Suspended Organic
Matter in the Middle and Lower Susitna River ...............................................20
4.8.1. Variances ........................................................................................21
4.9. Estimate Benthic Macroinvertebrate Colonization Rates in the Middle
Susitna River Segment under Pre-Project Baseline Conditions to Assist
in Evaluating Future Post-Project Changes to Productivity in the
Middle Susitna River .......................................................................................21
4.10. Variance: Characterize the Pre-Project Benthic Macroinvertebrate
Communities, with Regard to Species Composition and Abundance,
and Algal Production in Selected Susitna River Tributaries and Lake
Systems Located above Devils Canyon ...........................................................21
4.10.1. Benthic Macroinvertebrate Sampling ............................................22
4.10.2. Benthic Algae Sampling ................................................................23
4.10.3. Drift and Plankton Tows ................................................................24
4.10.4. Organic Matter ...............................................................................25
4.10.5. Water Quality .................................................................................25
5. Results ...............................................................................................................................27
5.1. Characterize the Pre-Project Benthic Macroinvertebrate and Algal
Communities with Regard to Species Composition and Abundance in
the Middle and Lower Susitna River ...............................................................27
5.1.1. Benthic Macroinvertebrate and Algal Sampling ............................27
5.2. Estimate Drift of Invertebrates in Selected Habitats within the Middle
and Lower Susitna River to Assess Food Availability to Juvenile and
Resident Fishes ................................................................................................34
5.2.1. RP-184 (Watana Dam) ...................................................................35
5.2.2. RP-173 (Stephan Lake Complex) ..................................................35
5.2.3. RP-141 (Indian River) ....................................................................36
5.2.4. RP-104 (Whiskers Slough) ............................................................36
5.2.5. RP-81 (Montana Creek) .................................................................37
5.3. Conduct a Feasibility Study in 2013 to Evaluate the Suitability of
Using Reference Sites on the Talkeetna River to Monitor Long-term
Project-related Change in Benthic Productivity ..............................................38
5.4. Conduct a Trophic Analysis, Using Trophic Modeling and Stable
Isotope Analysis, to Describe the Food Web Relationships in the
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii October 2015
Current Riverine Community within the Middle and Lower Susitna
River .................................................................................................................39
5.4.1. Develop a Trophic Model to Estimate How Environmental
Factors and Food Availability Affect the Growth Rate
Potential of Focal Fish Species under Current and Future
Conditions ......................................................................................39
5.4.2. Conduct Stable Isotope Analysis of Food Web Components
to Help Determine Energy Sources and Pathways in the
Riverine Communities ...................................................................43
5.5. Characterize the Invertebrate Compositions in the Diets of
Representative Fish Species in Relationship to their Source (benthic or
drift component)...............................................................................................46
5.5.1. 2013 Results Summary from Technical Memorandum .................46
5.5.2. 2014 Overall Dietary Patterns ........................................................47
5.6. Characterize Organic Matter Resources (e.g., available for
macroinvertebrate consumers) including Coarse Particulate Organic
Matter, Fine Particulate Organic Matter, and Suspended Organic
Matter in the Middle and Lower Susitna River ...............................................49
5.6.1. RP-184 (Watana Dam) ...................................................................50
5.6.2. RP-173 (Stephan Lake Complex) ..................................................51
5.6.3. RP-141 (Indian River) ....................................................................51
5.6.4. RP-104 (Whiskers Slough) ............................................................52
5.6.5. RP-81 (Montana Creek) .................................................................52
5.6.6. RP-TKA (Talkeetna River) ............................................................53
5.7. Estimate Benthic Macroinvertebrate Colonization Rates in the Middle
Susitna River Segment under Pre-Project Baseline Conditions to Assist
in Evaluating Future Post-Project Changes to Productivity in the
Middle Susitna River .......................................................................................53
5.8. Characterize the Pre-Project Benthic Macroinvertebrate Communities,
with Regard to Species Composition and Abundance, and Algal
Production in Selected Susitna River Tributaries and Lake Systems
Located above Devils Canyon .........................................................................54
5.8.1. Tributaries ......................................................................................54
5.8.2. Lakes ..............................................................................................57
6. Discussion..........................................................................................................................60
6.1. Benthic Macroinvertebrate Communities ........................................................60
6.2. Drift of Benthic Macroinvertebrates ................................................................62
6.3. Trophic Modeling ............................................................................................63
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv October 2015
6.4. Food Web Analysis via Stable Isotope Analysis and Fish Diet Analysis........65
6.4.1. Energy flow from algae and organic matter to freshwater
invertebrates ...................................................................................65
6.4.2. Energy flow to focal salmonid species ..........................................66
6.5. Organic Matter Resources ................................................................................69
6.6. Benthic Macroinvertebrates in Tributaries and Lakes above Devils
Canyon .............................................................................................................69
7. Conclusions .......................................................................................................................72
8. Literature Cited ...............................................................................................................73
9. Tables ................................................................................................................................83
10. Figures .............................................................................................................................138
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v October 2015
LIST OF TABLES
Table 4.2-1. Locations and descriptions of Focus Areas selected as sampling stations for the
River Productivity study in the Lower and Middle River Segments of the Susitna River in 2014.
“X” indicates site established at that habitat type, “(x)” indicates no site established at that
habitat type. ................................................................................................................................... 84
Table 4.2-2. Tributaries selected for sampling based on productivity estimates in Barrick et al.
(1983). ........................................................................................................................................... 85
Table 4.3-1. Adult emergence traps deployment locations with install and removal dates, and
count of number of collection visits with the number of successful samples collected in 2013. . 86
Table 4.3-2. Adult emergence trap deployment locations with 2013 collection period dates,
durations, estimated densities for successfully retrieved samples, and description of the trap
condition upon collection. ............................................................................................................. 87
Table 4.4-1. Sampling Stations and Seasonal Sampling Event dates of collection for the River
Productivity study in the Lower and Middle River Segments of the Susitna River, 2014. .......... 89
Table 4.4-2. Benthic drift and plankton tow sample totals for 2014 sampling during three
sampling events (Spr= Spring, Sum=Summer, Fall) for sampling sites in the Middle and Lower
River Segments of the Susitna River, for the River Productivity Study (9.8). ............................. 90
Table 4.6-1. Itemized listing of sample components collected and analyzed in 2014 for Stable
Isotope Analysis from the four sampling stations (16 sites total) in the Middle and Lower River
Segments of the Susitna River for the River Productivity Study. ................................................. 91
Table 4.7-1. Number of fish collected for fish gut content, scales, and stable isotope tissue
samples during the 2014 Spring Sampling event for each target species / age class from each
sampling site in the Middle and Lower River Segments of the Susitna River for the River
Productivity Study. ....................................................................................................................... 92
Table 4.7-2. Number of fish collected for fish gut content, scales, and stable isotope tissue
samples during the 2014 Summer Sampling event for each target species / age class from each
sampling site in the Middle and Lower River Segments of the Susitna River for the River
Productivity Study. ....................................................................................................................... 93
Table 4.7-3. Number of fish collected for fish gut content, scales, and stable isotope tissue
samples during the 2014 Fall Sampling event for each target species / age class from each
sampling site in the Middle and Lower River Segments of the Susitna River for the River
Productivity Study. ....................................................................................................................... 94
Table 4.8-1. Total number of Benthic and Drift Samples with organic matter components
collected for 2013 sampling during three sampling events (Spr=Spring, Sum=Summer, Fall) and
Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for
the River Productivity Study. ........................................................................................................ 95
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FERC Project No. 14241 Page vi October 2015
Table 4.10-1. Macroinvertebrate and algae sample totals for July 2014 sampling at nine selected
tributaries in the Middle and Upper River Segments of the Susitna River for the River
Productivity Study. ....................................................................................................................... 96
Table 4.10-2. Benthic macroinvertebrate and plankton tow sample totals for July 2014 sampling
at nine sites within three lakes located in the Upper River basin of the Susitna River for the River
Productivity Study. ....................................................................................................................... 96
Table 4.10-3. Water quality sample parameters taken for July 2014 sampling at nine selected
tributaries and nine lake sites in the Middle and Upper River Segments of the Susitna River for
the River Productivity Study. ........................................................................................................ 97
Table 5.1-1. Values of density, taxonomic richness, and relative abundance by habitat from adult
emergence trap samples collected in 2013 during the open water season for sites within the
Watana Dam Focus area (FA-184) in the Middle River Segment of the Susitna River for the
River Productivity Study............................................................................................................... 98
Table 5.1-2. Taxonomic composition metric values from adult emergence trap samples collected
in 2013 during the open water season for sites within the Watana Dam Focus area (FA -184) in
the Middle River Segment of the Susitna River for the River Productivity Study. ...................... 98
Table 5.1-3. Values of density, taxonomic richness, and relative abundance by habitat from adult
emergence trap samples collected in 2013 during the open water season for sites within the
Stephan Lake Complex Focus area (FA-173) in the Middle River Segment of the Susitna River
for the River Productivity Study. .................................................................................................. 99
Table 5.1-4. Taxonomic composition metric values from adult emergence trap samples collected
in 2013 during the open water season for sites within the Stephan Lake Complex Focus area
(FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study. 100
Table 5.1-5. Values of density, taxonomic richness, and relative abundance by habitat from adult
emergence trap samples collected in 2013 during the open water season for sites within the
Indian River Focus area (FA-141) in the Middle River Segment of the Susitna River for the
River Productivity Study............................................................................................................. 101
Table 5.1-6. Taxonomic composition metric values from adult emergence trap samples collected
in 2013 during the open water season for sites within the Indian River Focus area (FA-141) in
the Middle River Segment of the Susitna River for the River Productivity Study. .................... 102
Table 5.1-7. Values of density, taxonomic richness, and relative abundance by habitat from adult
emergence trap samples collected in 2013 during the open water season for sites within the
Whiskers Slough Focus area (FA-104) in the Middle River Segment of the Susitna River for the
River Productivity Study............................................................................................................. 103
Table 5.1-8. Taxonomic composition metric values from adult emergence trap samples collected
in 2013 during the open water season for sites within Whiskers Slough Focus area (FA-104) in
the Middle River Segment of the Susitna River for the River Productivity Study. .................... 104
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FERC Project No. 14241 Page vii October 2015
Table 5.1-9. Values of density, taxonomic richness, and relative abundance by habitat from adult
emergence trap samples collected in 2013 during the open water season for sites within the
Montana Creek Study Area (RP-81) in the Lower River Segment of the Susitna River for the
River Productivity Study............................................................................................................. 105
Table 5.1-10. Taxonomic composition metric values from adult emergence trap samples
collected in 2013 during the open water season for sites within the Montana Creek Study Area
(RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study. ... 106
Table 5.1-11. 2013 overall summary of LWD (Snag) metrics for sites at River Productivity
stations in Middle Reach above Devils Canyon. ........................................................................ 107
Table 5.1-12. 2013 overall summary of LWD (Snag) metrics for sites at River Productivity
stations in Middle Reach below Devils Canyon. ........................................................................ 108
Table 5.1-13. 2013 overall summary of LWD (Snag) metrics for sites at River Produ ctivity
stations in Lower Reach downstream of confluence with Chulitna River. ................................. 109
Table 5.2-1. 2014 overall summary of drift and plankton metrics for sites at River Productivity
stations in Middle Reach above Devils Canyon. ........................................................................ 110
Table 5.2-2. 2014 overall summary of drift and plankton metrics for sites at River Productivity
stations in Middle Reach below Devils Canyon. ........................................................................ 111
Table 5.2-3. 2014 overall summary of drift and plankton metrics for sites at River Productivity
stations in Lower Reach downstream of confluence with Chulitna River. ................................. 112
Table 5.4-1. Summary of water temperature patterns across years and macrohabitat types. All
metrics calculated from daily mean temperatures at each station. .............................................. 113
Table 5.4-2. Bioenergetics model results showing the growth, proportion of maximum
consumption (P), growth efficiency of juvenile Chinook (SCK) and Coho (SCO) salmon.
Consumption rates were estimated from observed growth between the spring and summer (Spr-
Sum) sampling events and between the summer and fall events (Sum-Fal). Model inputs were
pooled for combinations of main channel (MC), side channel (SC), side slough (SS), tributary
mouth (TM), and upland slough (US) macrohabitats based on a statistical analysis of growth
patterns. Growth of age-0 Coho Salmon did not differ among SC, SS, TM, and US habitats, so
inputs were pooled across these habitat types (All). ................................................................... 114
Table 5.4-3. Growth rate potential model results showing physical parameters and drift
invertebrate biomass density measured at each sampling event, as well as simulated daily ration,
growth rate potential, and proportion of maximum consumption (P) of age-1 Coho Salmon under
the observed conditions. Habitat types abbreviated as main channel (MC), side channel (SC),
side slough (SS), tributary mouth (TM). Bold text indicates sites with positive growth rate
potential values. .......................................................................................................................... 115
Table 5.4-3 (cont.). Growth rate potential model results showing physical parameters and drift
invertebrate biomass density measured at each sampling event, as well as simulated daily ration,
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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FERC Project No. 14241 Page viii October 2015
growth rate potential, and proportion of maximum consumption (P) of age-1 Coho Salmon under
the observed conditions. Habitat types abbreviated as main channel (MC), side channel (SC),
side slough (SS), tributary mouth (TM). Bold text indicates sites with positive growth rate
potential values. .......................................................................................................................... 116
Table 5.4-4. Results of MixSIAR Bayesian stable isotope diet models performed for juvenile
Chinook and Coho salmon, and Arctic Grayling and the potential freshwater, marine, and
terrestrial prey categories for all study sites with sufficient sample size (n > 2) in the Spring 2014
sampling event. ........................................................................................................................... 117
Table 5.4-5. Results of MixSIAR Bayesian stable isotope diet models performed for juvenile
Chinook and Coho salmon, and Arctic Grayling and the potential freshwater, marine, and
terrestrial prey categories for all study sites with sufficient sample size (n > 2) in the Summer
2014 sampling event. .................................................................................................................. 117
Table 5.4-6. Results of MixSIAR Bayesian stable isotope diet models performed for juvenile
Chinook and Coho salmon, and Arctic Grayling and the potential freshwater, marine, and
terrestrial prey categories for all study sites with sufficient sample size (n > 2) in the Fall 2014
sampling event. ........................................................................................................................... 118
Table 5.5-1. MANCOVA models testing for ontogenetic, temporal, and spatial differences in
diet composition. Degrees of freedom (df) are listed for both hypothesis (hyp) and error terms.
Type-II p-values are reported. ..................................................................................................... 119
Table 5.6-1. Overall summary of benthic organic matter components collected for 2013
sampling over three sampling events (Spring, Summer, Fall) and Post-Storm sampling for sites
in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
..................................................................................................................................................... 120
Table 5.6-2. Overall summary of drift (seston) organic matter components collected for 2013
sampling over three sampling events (Spring, Summer, Fall) and Post-Storm sampling for sites
in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
..................................................................................................................................................... 121
Table 5.6-3. Overall summary of drift (seston) organic matter components collected for 2014
sampling over three sampling events (Spring, Summer, Fall) and Post-Storm sampling for sites
in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
..................................................................................................................................................... 122
Table 5.6-4. Summary of mean values of benthic organic matter components collected for 2013
sampling over three sampling events (Spring, Summer, Fall) and Post-Storm sampling for sites
in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
..................................................................................................................................................... 123
Table 5.6-5. Summary of mean values of drift (seston) organic matter components collected for
2013 sampling over three sampling events (Spring, Summer, Fall) and Post -Storm sampling for
sites in the Middle and Lower River Segments of the Susitna River for the River Productivity
Study. .......................................................................................................................................... 124
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FERC Project No. 14241 Page ix October 2015
Table 5.6-6. Summary of mean values of drift (seston) organic matter components collected for
2014 sampling over three sampling events (Spring, Summer, Fall) and Post -Storm sampling for
sites in the Middle and Lower River Segments of the Susitna River for the River Productivity
Study. .......................................................................................................................................... 125
Table 5.8-1. Mean metric values (n=5) from Hess samples collected in July 2014 for sites in
nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna
River for the River Productivity Study. ...................................................................................... 126
Table 5.8-2. Summary of benthic organic matter components collected in July 2014 for sites in
nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna
River for the River Productivity Study. ...................................................................................... 127
Table 5.8-3. Nutrient levels measured from water quality grab samples, and mean chlorophyll-a,
pheophytin, and Ash Free Dry Mass (AFDM) values (n=5) collected in July 2014 for sites in
nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna
River for the River Productivity Study. ...................................................................................... 127
Table 5.8-4. Mean metric values (n=2) from drift net samples collected in July 2014 for sites in
nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna
River for the River Productivity Study. ...................................................................................... 128
Table 5.8-5. Summary of drift (seston) organic matter components collected in July 2014 for
sites in nine tributaries above Devils Canyon in the Middle and Upper River segments of the
Susitna River for the River Productivity Study. ......................................................................... 129
Table 5.8-6. In-situ water quality measurements collected in July 2014 at sites in nine tributaries
above Devils Canyon in the Middle and Upper River segments of the Susitna River for the River
Productivity Study. ..................................................................................................................... 129
Table 5.8-7. Mean metric values (n=5) from petite Ponar grab samples collected in July 2014 for
sites within three lakes in the Upper River Segment of the Susitna River for the River
Productivity Study. ..................................................................................................................... 130
Table 5.8-8. Summary of benthic organic matter components from petite Ponar samples (n=5)
collected in July 2014 for sites within three lakes in the Upper River Segment of the Susitna
River for the River Productivity Study. ...................................................................................... 131
Table 5.8-9. Metric values from qualitative shoreline benthic D-net sweep samples collected in
July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study............................................................................................................. 132
Table 5.8-10. Mean metric values (n=5) from plankton tow samples collected in July 2014 for
sites within three lakes in the Upper River Segment of the Susitna River for the River
Productivity Study. Density and biomass estimates are areal (per m2) as opposed to by volume.
..................................................................................................................................................... 133
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FERC Project No. 14241 Page x October 2015
Table 5.8-11. Mean Secchi depths, light extinction coefficients, and calculated euphotic zone
depths for sites within three lakes in the Upper River Segment of the Susitna River for the River
Productivity Study in July 2014. ................................................................................................. 134
Table 5.8-12. Nutrient and chlorophyll-a levels measured from water quality grab samples
collected near surface, near euphotic depth, and near-bottom in July 2014 for sites within three
lakes in the Upper River Segment of the Susitna River for the River Productivity Study. ........ 135
Table 6.6-1: Comparison of river site water quality with Alaska standards and other typical
measurements in the region. ....................................................................................................... 136
Table 6.6-2. Comparison of lake site water quality with other lakes in the region. .................. 137
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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FERC Project No. 14241 Page xi October 2015
LIST OF FIGURES
Figure 3-1. Middle Susitna River Segment, with the four River Productivity sampling stations
/Instream Flow Focus Areas selected for the River Productivity Study, plus the sampling station
for reference sites on the Talkeetna River. ................................................................................. 139
Figure 3-2. Lower Susitna River Segment, with Montana Creek area River Productivity
sampling station selected for the River Productivity Study. ....................................................... 140
Figure 3-3. Tributary sites and lake sites above Devils Canyon in the Middle and Upper
Segments, selected for the 2014 River Productivity Study......................................................... 141
Figure 3-4. Lake sites above Devils Canyon in the Middle and Upper Segments, selected for the
2014 River Productivity Study.................................................................................................... 142
Figure 4.2-1. Focus Area 184 (Watana Dam), and the three River Productivity sampling sites.
..................................................................................................................................................... 143
Figure 4.2-2. Focus Area FA-173 (Stephan Lake Complex), and the four River Productivity
sampling sites. Site RP-173-3, originally identified as a side channel, has been reclassified as a
side slough by the Aquatic Habitat Study (Study 9.9) in 2014. .................................................. 144
Figure 4.2-3. Focus Area FA-141 (Indian River), and the four River Productivity sampling sites.
..................................................................................................................................................... 145
Figure 4.2-4. Focus Area FA-104 (Whiskers Slough), and the five River Productivity sampling
sites. ............................................................................................................................................ 146
Figure 4.2-5. Station RP-81 (Montana Creek), and the four River Productivity sampling sites.
..................................................................................................................................................... 147
Figure 4.3-1. Size distribution of the 155 snag pieces collected in 2013 during the open water
season within the all sites the Susitna River for the River Productivity Study. .......................... 148
Figure 4.6-1. Sampling equipment used to collect benthic macroinvertebrates in streams and
rivers Top left: Hess stream sampler. Top right: drift nets. Bottom left: floating aquatic insect
emergence trap. Bottom right: D-net kick sampler. .................................................................. 149
Figure 4.10-1. Sampling equipment used to collect invertebrates and water quality samples from
lakes. Top left: Petite Ponar grab sampler. Top right: plankton net. Bottom left: PAR meter and
in situ YSI multiprobe water quality meter. Bottom right: Van Dorn vertical water sampler. . 150
Figure 5.1-1. Mean emergence trap density estimates (n=1) collected in 2013 during the open
water season within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the
Susitna River for the River Productivity Study. Bar width indicates the length of period
deployment for the emergence trap. “N/A” indicates no sample was collected during that time
period. ......................................................................................................................................... 151
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FERC Project No. 14241 Page xii October 2015
Figure 5.1-2. Mean emergence trap density estimates (n=1) collected in 2013 during the open
water season within the Stephan Lake complex Focus Area (FA-173) in the Middle River
Segment of the Susitna River for the River Productivity Study. Bar width indicates the length of
period deployment for the emergence trap. “N/A” indicates no sample was collected during that
time period. ................................................................................................................................. 152
Figure 5.1-3. Mean emergence trap density estimates (n=1) collected in 2013 during the open
water season within the Indian River Focus Area (FA-141) in the Middle River Segment of the
Susitna River for the River Productivity Study. Bar width indicates the length of period
deployment for the emergence trap. “N/A” indicates no sample was collected during that time
period. ......................................................................................................................................... 153
Figure 5.1-4. Mean emergence trap density estimates (n=1) collected in 2013 during the open
water season within the Whiskers Slough Focus Area (FA-104) in the Middle River Segment of
the Susitna River for the River Productivity Study. Bar width indicates the length of period
deployment for the emergence trap. “N/A” indicates no sample was collected during that time
period. ......................................................................................................................................... 154
Figure 5.1-5. Mean emergence trap density estimates (n=1) collected in 2013 during the open
water season within the Montana Creek study area (RP-81) in the Lower River Segment of the
Susitna River for the River Productivity Study. Bar width indicates the length of period
deployment for the emergence trap. “N/A” indicates no sample was collected during that time
period. ......................................................................................................................................... 155
Figure 5.1-6. Mean density estimates collected from woody debris in 2013 during three
sampling events for sites within the Watana Dam Focus Area (FA-184) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “N/A” indicates no sample was collected. ............................................... 156
Figure 5.1-7. Mean taxa richness estimates collected from woody debris in 2013 during three
sampling events for sites within the Watana Dam Focus Area (FA-184) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “N/A” indicates no sample was collected. ............................................... 156
Figure 5.1-8. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates
collected from woody debris in 2013 during three sampling events for sites within the Watana
Dam Focus Area (FA-184) in the Middle River Segment of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no
sample was collected................................................................................................................... 157
Figure 5.1-9. Mean density estimates collected from woody debris in 2013 during three
sampling events for sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle
River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. “N/A” indicates no sample was collected. .................................. 157
Figure 5.1-10. Mean taxa richness estimates collected from woody debris in 2013 during three
sampling events for sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle
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River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. “N/A” indicates no sample was collected. .................................. 158
Figure 5.1-11. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates
collected from woody debris in 2013 during three sampling events for sites within the Stephan
Lake Complex Focus Area (FA-173) in the Middle River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates
no sample was collected. ............................................................................................................. 158
Figure 5.1-12. Mean density estimates collected from woody debris in 2013 during three
sampling events for sites within the Indian River Focus Area (FA-141) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “N/A” indicates no sample was collected. ............................................... 159
Figure 5.1-13. Mean taxa richness estimates collected from woody debris in 2013 during three
sampling events for sites within the Indian River Focus Area (FA-141) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “N/A” indicates no sample was collected. ............................................... 159
Figure 5.1-14. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates
collected from woody debris in 2013 during three sampling events for sites within the Indian
River Focus Area (FA-141) in the Middle River Segment of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no
sample was collected................................................................................................................... 160
Figure 5.1-15. Mean density estimates collected from woody debris in 2013 during three
sampling events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “N/A” indicates no sample was collected. ............................................... 160
Figure 5.1-16. Mean taxa richness estimates collected from woody debris in 2013 during three
sampling events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “N/A” indicates no sample was collected. ............................................... 161
Figure 5.1-17. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates
collected from woody debris in 2013 during three sampling events for sites within the Whiskers
slough Focus Area (FA-104) in the Middle River Segment of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no
sample was collected................................................................................................................... 161
Figure 5.1-18. Mean density estimates collected from woody debris in 2013 during three
sampling events for sites within the Montana Creek Study Area (RP-81 in the Lower River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “N/A” indicates no sample was collected. “0” indicates zero organisms
were collected on collected woody debris. ................................................................................. 162
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Figure 5.1-19. Mean taxa richness estimates collected from woody debris in 2013 during three
sampling events for sites within the Montana Creek Study Area (RP-81) in the Lower River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “N/A” indicates no sample was collected. “0” indicates zero organisms
were collected on collected woody debris. ................................................................................. 162
Figure 5.1-20. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates
collected from woody debris in 2013 during three sampling events for sites within the Montana
Creek Study Area (RP-81) in the Lower River Segment of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no
sample was collected. “0” indicates zero organisms were collected on collected woody debris.
..................................................................................................................................................... 163
Figure 5.2-1. Mean drift density estimates from drift samples (n=2) collected in 2014 during
three sampling events for sites within the Watana Dam Focus Area (FA-184) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. ................................................................................................................... 163
Figure 5.2-2. Mean drift taxa richness estimates from drift samples (n=2) collected in 2014
during three sampling events for sites within the Watana Dam Focus Area (FA-184) in the
Middle River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. ................................................................................. 164
Figure 5.2-3. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5)
collected in 2014 during three sampling events for sites within the Stephan Lake Complex Focus
Area (FA-173) in the Middle River Segment of the Susitna River for the River Productivity
Study. Error bars represent 95-percent confidence intervals. Bars marked with a “P” are
plankton tows. ............................................................................................................................. 164
Figure 5.2-4. Mean drift taxa richness estimates from drift samples (n=2) and plankton tows
(n=5) collected in 2014 during three sampling events for sites within the Stephan Lake Complex
Focus Area (FA-173) in the Middle River Segment of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. Bars marked with a
“P” are plankton tows. ................................................................................................................ 165
Figure 5.2-5. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5)
collected in 2014 during three sampling events for sites within the Indian River Focus Area (FA-
141) in the Middle River Segment of the Susitna River for the River Productivity Study. Error
bars represent 95-percent confidence intervals. Bars marked with a “P” are plankton tows. ... 165
Figure 5.2-6. Mean drift taxa richness estimates from drift samples (n=2) and plankton tows
(n=5) collected in 2014 during three sampling events for sites within the Indian River Focus
Area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity
Study. Error bars represent 95-percent confidence intervals. Bars marked with a “P” are
plankton tows. ............................................................................................................................. 166
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Figure 5.2-7. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5)
collected in 2014 during three sampling events for sites within the Whiskers Slough Focus Area
(FA-104) in the Middle River Segment of the Susitna River for the River Productivity Study.
Error bars represent 95-percent confidence intervals. Bars marked with a “P” are plankton tows.
“N/A” - no samples were collected. ............................................................................................ 166
Figure 5.2-8. Mean drift taxa richness estimates from drift samples (n=2) and plankton tows
(n=5) collected in 2014 during three sampling events for sites within the Whiskers Slough Focus
Area (FA-104) in the Middle River Segment of the Susitna River for the River Productivity
Study. Error bars represent 95-percent confidence intervals. Bars marked with a “P” are
plankton tows. “N/A” - no samples were collected. ................................................................... 167
Figure 5.2-9. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5)
collected in 2014 during three sampling events for sites within the Montana Creek area (RP-81)
in the Lower River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. Bars marked with a “P” are plankton tows. ........... 167
Figure 5.2-10. Mean drift taxa richness estimates from drift samples (n=2) and plankton tows
(n=5) collected in 2014 during three sampling events for sites within the Montana Creek area
(RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study.
Error bars represent 95-percent confidence intervals. Bars marked with a “P” are plankton tows.
..................................................................................................................................................... 168
Figure 5.4-1. Length-frequency distributions of Chinook Salmon and Coho Salmon sampled
during June 2013 and June 2014 in the study area of the River Productivity Study by the Fish
Distribution and Abundance in the Middle and Lower River Study. Distributions are truncated at
60 mm fork length to show size structure of age-0 fish. ............................................................. 169
Figure 5.4-2. Seasonal length-at-age relationship of Chinook Salmon collected during 2013 and
aged from scales. ......................................................................................................................... 170
Figure 5.4-3. Seasonal length-at-age relationship of Coho Salmon collected during 2013 and
aged from scales. ......................................................................................................................... 171
Figure 5.4-4. Seasonal length-at-age relationship of Rainbow Trout collected during 2013 and
aged from scales. ......................................................................................................................... 172
Figure 5.4-5. Seasonal length-at-age relationship of Chinook Salmon aged from scales during
2014............................................................................................................................................. 173
Figure 5.4-6. Seasonal length-at-age relationship of Coho Salmon aged from scales during 2014.
..................................................................................................................................................... 174
Figure 5.4-7. Seasonal length-at-age relationship of Arctic Grayling aged from scales during
2014............................................................................................................................................. 175
Figure 5.4-8. Seasonal length-at-age relationship of Rainbow Trout aged from scales during
2014............................................................................................................................................. 176
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Figure 5.4-9. Seasonal mean weights of age-0 Chinook Salmon sampled in main channel and
side channel habitats (main/side channel) and side sloughs, tributary mouths, and upland slough
habitats (off-channel) during 2013 and 2014. Symbols represent means ± 1 SE. The mean
weight of age-0 Chinook Salmon during spring of each year was estimated from length-
frequency distributions and a length-weight relationship, and these values are reported for all
habitats combined, without error. ............................................................................................... 177
Figure 5.4-10. Seasonal mean weights of age-0 Coho Salmon sampled in all habitats (side
channel, side slough, tributary mouth, and upland slough) during 2013 and 2014. Symbols
represent means ± 1 SE. The mean weight of age-0 Coho Salmon during spring of each year was
estimated from length-frequency distributions and a length-weight relationship, and these values
are reported without error. .......................................................................................................... 178
Figure 5.4-11. Seasonal mean weights of age-1 Coho Salmon sampled in side channel and
tributary mouth habitats (SC / TM) and side sloughs and upland slough habitats (SS / US) during
2013 and 2014. Symbols represent means ± 1 SE. .................................................................... 179
Figure 5.4-12. Daily mean stream temperatures recorded at all study sites during 2013 and 2014.
..................................................................................................................................................... 180
Figure 5.4-13. Daily mean stream temperatures recorded at each site in 2013, displayed by
macrohabitat type (top panel); daily stream temperatures averaged across all sites within each
habitat type (bottom panel). ........................................................................................................ 181
Figure 5.4-14. Daily mean stream temperatures recorded at each site in 2014, displayed by
macrohabitat type (top panel); daily stream temperatures averaged across all sites within each
macrohabitat type (bottom panel). .............................................................................................. 182
Figure 5.4-15. Daily mean stream temperatures recorded at each site in 2014 (gray); sites where
the stomach contents of juvenile salmon contained salmon eggs are plotted in black. .............. 183
Figure 5.4-16. Associations between temperature, drift invertebrate biomass density, flow
velocity, turbidity and model-estimated growth rate potential of drift feeding age-1 Coho
Salmon. ....................................................................................................................................... 184
Figure 5.4-17. Monthly length frequency distributions of Chinook Salmon and Coho Salmon
sampled in the Middle and Lower Susitna River during 2013 and 2014. ................................... 185
Figure 5.4-18. Comparisons of the mean dietary proportions of juvenile Chinook and Coho
salmon across sampling periods in 2013, as determined by Bayesian stable isotope mixing
models before genetic analysis of juvenile salmon tissues (Pre) and after the incorporation of
species reassignments and informative priors from stomach contents (Post). ............................ 186
Figure 5.4-19. Comparisons of the mean dietary proportions of juvenile Chinook and Coho
salmon across macrohabitats in 2013, as determined by Bayesian stable isotope mixing models
before genetic analysis of juvenile salmon tissues (Pre) and after the incorporation of species
reassignments and informative priors from stomach contents (Post). ........................................ 187
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Figure 5.4-20. Comparisons of the mean dietary proportions of juvenile Chinook and Coho
salmon across RP Focus Areas in 2013, as determined by Bayesian stable isotope mixing models
before genetic analysis of juvenile salmon tissues (Pre) and after the incorporation of species
reassignments and informative priors from stomach contents (Post). ........................................ 188
Figure 5.4-21. Median 13C values (with 2.5, 25, 75, 97.5% ranges; open circles represent values
outside the distribution) for organic matter, algae, and aquatic invertebrates pooled by
macrohabitat type. ....................................................................................................................... 189
Figure 5.4-22. Median 13C values (with 2.5, 25, 75, 97.5% ranges; open circles represent
values outside the distribution) for organic matter, algae, and aquatic invertebrates pooled by
reach (Focus Area). ..................................................................................................................... 190
Figure 5.4-23. Median 13C values (with 2.5, 25, 75, 97.5% ranges; open circles represent values
outside the distribution) for organic matter, algae, and aquatic invertebrates pooled by season.
..................................................................................................................................................... 191
Figure 5.4-24. Linear regressions of aquatic invertebrate consumer group 13C against potential
food source (periphyton [filled circles] and terrestrial organic matter [open circles]) 13C for
2014. Each data point represents site-specific mean invertebrate 13C vs. site-specific mean
source 13C for all seasons combined. ........................................................................................ 192
Figure 5.4-25. Diet composition of juvenile Chinook Salmon in 2014, as estimated with
MixSIAR Bayesian mixing models. Box plots show the mean proportional contribution (with
2.5, 25, 75, and 97.5 credibility intervals) of each prey category to the diet. Contributions of all
diet sources from a single sampling event are stacked vertically across panels. Model results are
grouped so that all spatial and temporal dietary trends addressed in this study may be discerned:
first by macrohabitat as indicated by labels at the bottom of the plot, then by season as indicated
by panel color and labels at the top of the plot (SP = spring, SU = summer, FA = fall), and lastly
by increasing distance from the river mouth as indicated by box color (see legend). ................ 193
Figure 5.4-26. Diet composition of juvenile Coho Salmon in 2014, as estimated with MixSIAR
Bayesian mixing models. Box plots show the mean proportional contribution (with 2.5, 25, 75,
and 97.5 credibility intervals) of each prey category to the diet. Contributions of all diet sources
from a single sampling event are stacked vertically across panels. Model results are grouped so
that all spatial and temporal dietary trends addressed in this study may be discerned: first by
macrohabitat as indicated by labels at the bottom of the plot, then by season as indicated by panel
color and labels at the top of the plot (SP = spring, SU = summer, FA = fall), and lastly by
increasing distance from the river mouth as indicated by box color (see legend). ..................... 194
Figure 5.4-27. Diet composition of Arctic Grayling in 2014, as estimated with MixSIAR
Bayesian mixing models. Box plots show the mean proportional contribution (with 2.5, 25, 75,
and 97.5 credibility intervals) of each prey category to the diet. Contributions of all diet sources
from a single sampling event are stacked vertically across panels. Model results are grouped so
that all spatial and temporal dietary trends addressed in this study may be discerned: first by
macrohabitat as indicated by labels at the bottom of the plot, then by season as indicated by panel
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color and labels at the top of the plot (SP = spring, SU = summer, FA = fall), and lastly by
increasing distance from the river mouth as indicated by box color (see legend). ..................... 195
Figure 5.4-28. Diet composition of resident salmonids (GRA: Arctic Grayling; TRB: Rainbow
Trout) in 2014, as estimated with MixSIAR Bayesian mixing models. Boxplots show the mean
proportional contribution (with 2.5, 25, 75, and 97.5 credibility intervals) of each prey category
to the diet. Contributions of all diet sources from a single sampling event are stacked vertically
across panels. Model results are grouped by season. .................................................................. 196
Figure 5.5-1. Overall diet composition of two size classes of Arctic Grayling (GRA), juvenile
Chinook Salmon (SCK), juvenile Coho Salmon (SCO), and two size classes of Rainbow Trout
(TRB) sampled during 2013 and 2014 in the Susitna River. Size classes were defined as small
(SM; ≤ 120 mm fork length [FL]) and large (LG; > 120 mm FL). Diet proportions (by dry mass)
were determined by stomach content analysis. Prey items were categorized as aquatic life-stages
of freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-stages of freshwater invertebrates
(FW inv. [Ter LS]), terrestrial invertebrates (Ter. inv.), fish and non-salmonid fish eggs (Fish &
non-sm. eggs), or salmon eggs. ................................................................................................... 197
Figure 5.5-2. Annual and seasonal patterns of diet composition of juvenile Chinook Salmon
(SCK) and juvenile Coho Salmon (SCO) sampled during 2013 and 2014 in the Susitna River.
Diet proportions (by dry mass) were determined by stomach content analysis. Seasons are
abbreviated as spring (Spr), summer (Sum), and fall (Fal). Prey items were categorized as
aquatic life-stages of freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-stages of
freshwater invertebrates (FW inv. [Ter LS]), terrestrial invertebrates (Ter. inv.), fish and non-
salmonid fish eggs (Fish & non-sm. eggs), or salmon eggs. ...................................................... 198
Figure 5.5-3. Proportion (by dry mass) of salmon eggs in the stomach contents of individual
Chinook Salmon, Coho Salmon, and Rainbow Trout sampled by gastric lavage, as a function of
fork length. .................................................................................................................................. 199
Figure 5.5-4. Proportion (by dry mass) of fish in the stomach contents of individual Arctic
Grayling, Chinook Salmon, Coho Salmon, and Rainbow Trout sampled by gastric lavage, as a
function of fork length. ............................................................................................................... 200
Figure 5.5-5. Seasonal diet composition of two size classes of Arctic Grayling (GRA) sampled
during 2014 and two size classes of Rainbow Trout (TRB) sampled during 2013 and 2014 in the
Susitna River. Size classes were defined as small (SM; ≤ 120 mm fork length [FL]) and large
(LG; > 120 mm FL). Diet proportions (by dry mass) were determined by stomach content
analysis. Prey items were categorized as aquatic life-stages of freshwater invertebrates (FW inv.
[Aqu LS]), terrestrial life-stages of freshwater invertebrates (FW inv. [Ter LS]), terrestrial
invertebrates (Ter. inv.), fish and non-salmonid fish eggs (Fish & non-sm. eggs), or salmon eggs.
..................................................................................................................................................... 201
Figure 5.5-6. Large-scale spatial patterns of diet composition of two size classes of Arctic
Grayling (GRA) sampled during 2014 and two size classes of Rainbow Trout (TRB) sampled
during 2013 and 2014 in the Susitna River. Fish were sampled in five study stations (RP-184,
RP-173, RP-141, RP-104, and RP-81), which were abbreviated in the x-axis labels by project
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river mile. Size classes were defined as small (SM; ≤ 120 mm fork length [FL]) and large (LG; >
120 mm FL). Diet proportions (by dry mass) were determined by stomach content analysis.
Prey items were categorized as aquatic life-stages of freshwater invertebrates (FW inv. [Aqu
LS]), terrestrial life-stages of freshwater invertebrates (FW inv. [Ter LS]), terrestrial
invertebrates (Ter. inv.), fish and non-salmonid fish eggs (Fish & non-sm. eggs), or salmon eggs.
..................................................................................................................................................... 202
Figure 5.5-7. Habitat-based patterns of diet composition of two size classes of Arctic Grayling
(GRA) sampled during 2014 and two size classes of Rainbow Trout (TRB) sampled during 2013
and 2014 in the Susitna River. Fish were sampled in five macrohabitat types: main channel
(MC), side channel (SC), side slough (SS), tributary mouth (TM), and upland slough (US). Size
classes were defined as small (SM; ≤ 120 mm fork length [FL]) and large (LG; > 120 mm FL).
Diet proportions (by dry mass) were determined by stomach content analysis. Prey items were
categorized as aquatic life-stages of freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-
stages of freshwater invertebrates (FW inv. [Ter LS]), terrestrial invertebrates (Ter. inv.), fish
and non-salmonid fish eggs (Fish & non-sm. eggs), or salmon eggs. ........................................ 203
Figure 5.5-8. Large-scale spatial patterns of diet composition of juvenile Chinook Salmon
(SCK) and juvenile Coho Salmon (SCO) sampled during 2013 and 2014 in the Susitna River.
Fish were sampled in five study stations (RP-184, RP-173, RP-141, RP-104, and RP-81), which
were abbreviated in the x-axis labels by project river mile. Size classes were defined as small
(SM; ≤ 120 mm fork length [FL]) and large (LG; > 120 mm FL). Diet proportions (by dry mass)
were determined by stomach content analysis. Prey items were categorized as aquatic life-stages
of freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-stages of freshwater invertebrates
(FW inv. [Ter LS]), terrestrial invertebrates (Ter. inv.), fish and non-salmonid fish eggs (Fish &
non-sm. eggs), or salmon eggs. ................................................................................................... 204
Figure 5.5-9. Habitat-based patterns of diet composition of juvenile Chinook Salmon (SCK) and
juvenile Coho Salmon (SCO) sampled during 2013 and 2014 in the Susitna River. Fish were
sampled in five macrohabitat types: main channel (MC), side channel (SC), side slough (SS),
tributary mouth (TM), and upland slough (US). Size classes were defined as small (SM; ≤ 120
mm fork length [FL]) and large (LG; > 120 mm FL). Diet proportions (by dry mass) were
determined by stomach content analysis. Prey items were categorized as aquatic life-stages of
freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-stages of freshwater invertebrates
(FW inv. [Ter LS]), terrestrial invertebrates (Ter. inv.), fish and non-salmonid fish eggs (Fish &
non-sm. eggs), or salmon eggs. ................................................................................................... 205
Figure 5.6-1. Mean benthic organic matter estimates (g/m2) from Hess samples collected in 2013
during three sampling events for sites within the Watana Dam Focus Area (FA-184) in the
Middle River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. ................................................................................. 206
Figure 5.6-2. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2013 during three sampling events for sites within the Watana Dam Focus Area (FA-184) in
the Middle River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. ................................................................................. 206
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Figure 5.6-3. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2014 during three sampling events for sites within the Watana Dam Focus Area (FA-184) in
the Middle River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. ................................................................................. 207
Figure 5.6-4. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab
samples collected in 2013 during three sampling events for sites within the Stephan Lake
Complex Focus Area (FA-173) in the Middle River Segment of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. ................................ 207
Figure 5.6-5. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2013 during three sampling events for sites within the Stephan Lake Complex Focus Area
(FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study.
Error bars represent 95-percent confidence intervals. “P” indicates plankton tow samples were
taken, and no organic matter was collected. ............................................................................... 208
Figure 5.6-6. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2014 during three sampling events for sites within the Stephan Lake Complex Focus Area
(FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study.
Error bars represent 95-percent confidence intervals. “P” indicates plankton tow samples were
taken, and no organic matter was collected. ............................................................................... 208
Figure 5.6-7. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab
samples collected in 2013 during three sampling events for sites within the Indian River Focus
Area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity
Study. Error bars represent 95-percent confidence intervals. .................................................... 209
Figure 5.6-8. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2013 during three sampling events for sites within the Indian River Focus Area (FA-141) in
the Middle River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. “P” indicates plankton tow samples were taken, and
no organic matter was collected. “N/A” indicates that no samples were collected. ................... 209
Figure 5.6-9. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2014 during three sampling events for sites within the Indian River Focus Area (FA-141) in
the Middle River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. “P” indicates plankton tow samples were taken, and
no organic matter was collected. ................................................................................................. 210
Figure 5.6-10. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab
samples collected in 2013 during three sampling events for sites within the Whiskers Slough
Focus Area (FA-104) in the Middle River Segment of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. ................................ 210
Figure 5.6-11. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2013 during three sampling events for sites within the Whiskers Slough Focus Area (FA-104)
in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars
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represent 95-percent confidence intervals. “P” indicates plankton tow samples were taken, and
no organic matter was collected. ................................................................................................. 211
Figure 5.6-12. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2014 during three sampling events for sites within the Whiskers Slough Focus Area (FA-104)
in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. “P” indicates plankton tow samples were taken, and
no organic matter was collected. ................................................................................................. 211
Figure 5.6-13. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab
samples collected in 2013 during three sampling events for sites within the Montana Creek Study
Area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study.
Error bars represent 95-percent confidence intervals. ................................................................ 212
Figure 5.6-14. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2013 during three sampling events for sites within the Montana Creek Study Area (RP-81) in
the Lower River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. “P” indicates plankton tow samples were taken, and
no organic matter was collected. “N/A” indicates that no samples were collected. ................... 212
Figure 5.6-15. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2013 during three sampling events for sites within the Montana Creek Study Area (RP-81) in
the Lower River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. “P” indicates plankton tow samples were taken, and
no organic matter was collected. ................................................................................................. 213
Figure 5.6-16. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab
samples collected in 2013 during three sampling events for sites within the Talkeetna River
Study Area (RP-TKA) in the for the River Productivity Study. Error bars represent 95-percent
confidence intervals. ................................................................................................................... 213
Figure 5.6-17. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected
in 2013 during three sampling events for sites within the Talkeetna River Study Area (RP-TKA)
for the River Productivity Study. Error bars represent 95-percent confidence intervals. “P”
indicates plankton tow samples were taken, and no organic matter was collected. ................... 214
Figure 5.8-1. Mean density estimates (n=5) from Hess samples collected in July 2014 for sites in
nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals. 214
Figure 5.8-2. Mean and total taxa richness estimates (n=5) from Hess samples collected in July
2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River segments
of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. ...................................................................................................................................... 215
Figure 5.8-3. Mean and total EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness
estimates (n=5) from Hess samples collected in July 2014 for sites in nine tributaries above
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Devils Canyon in the Middle and Upper River segments of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. ............................... 215
Figure 5.8-4. Mean percent relative abundances of major taxonomic groups from Hess samples
(n=5) collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and
Upper River segments of the Susitna River for the River Productivity Study. .......................... 216
Figure 5.8-5. Mean percent relative abundances of functional feeding groups from Hess samples
(n=5) collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and
Upper River segments of the Susitna River for the River Productivity Study. .......................... 216
Figure 5.8-6. Mean benthic organic matter estimates (g/m2) from Hess samples (n=5) collected
in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River
segments of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. ................................................................................................................... 217
Figure 5.8-7. Mean chlorophyll-a (mg/m2) from composite algae samples (n=5) collected in July
2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River segments
of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. ...................................................................................................................................... 217
Figure 5.8-8. Mean ash free dry mass (AFDM, g/m2) from composite algae samples (n=5)
collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper
River segments of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. ...................................................................................................... 218
Figure 5.8-9. Mean drift density estimates from drift net samples (n=2) collected in July 2014
for sites in nine tributaries above Devils Canyon in the Middle and Upper River segments of the
Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. ...................................................................................................................................... 218
Figure 5.8-10. Mean and total drift taxa richness estimates from drift net samples (n=2)
collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper
River segments of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. ...................................................................................................... 219
Figure 5.8-11. Mean and total drift EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness
estimates from drift samples (n=2) collected in July 2014 for sites in nine tributaries above
Devils Canyon in the Middle and Upper River segments of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. ................................ 219
Figure 5.8-12. Mean percent relative abundances of major taxonomic groups from drift net
samples (n=2) collected in July 2014 for sites in nine tributaries above Devils Canyon in the
Middle and Upper River segments of the Susitna River for the River Productivity Study. ....... 220
Figure 5.8-13. Mean drift (seston) organic matter estimates (g/m2) from drift net samples (n=2)
collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper
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River segments of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. ...................................................................................................... 220
Figure 5.8-14. Mean density estimates (n=5) from petite Ponar samples collected in July 2014
for sites within three lakes in the Upper River Segment of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals. ............................... 221
Figure 5.8-15. Mean and total taxa richness estimates (n=5) from petite Ponar samples collected
in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals. ..................... 221
Figure 5.8-15. Mean and total chironomid (midge) taxa richness estimates (n=5) from petite
Ponar samples collected in July 2014 for sites within three lakes in the Upper River Segment of
the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. ...................................................................................................................................... 222
Figure 5.8-16. Mean percent relative abundances of major taxonomic groups from petite Ponar
samples collected in July 2014 for sites within three lakes in the Upper River Segment of the
Susitna River for the River Productivity Study. ......................................................................... 222
Figure 5.8-17. Mean percent relative abundances of functional feeding groups from petite Ponar
samples collected in July 2014 for sites within three lakes in the Upper River Segment of the
Susitna River for the River Productivity Study. ......................................................................... 223
Figure 5.8-18. Mean benthic organic matter estimates (g/m2) from petite Ponar samples
collected in July 2014 for sites within three lakes in the Upper River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals. . 223
Figure 5.8-18. Taxa richness, chironomid taxa richness, and EPT taxa richness estimates from
qualitative shoreline D-net sweep samples collected in July 2014 for sites within three lakes in
the Upper River Segment of the Susitna River for the River Productivity Study. ..................... 224
Figure 5.8-19. Mean percent relative abundances of major taxonomic groups from qualitative
shoreline D-net sweep samples collected in July 2014 for sites within three lakes in the Upper
River Segment of the Susitna River for the River Productivity Study. ...................................... 224
Figure 5.8-20. Mean percent relative abundances of functional feeding groups from qualitative
shoreline D-net sweep samples collected in July 2014 for sites within three lakes in the Upper
River Segment of the Susitna River for the River Productivity Study. ...................................... 225
Figure 5.8-21. Mean plankton tow density estimates (individuals/m2) from vertical tow net
samples (n=5) collected in July 2014 for sites within three lakes in the Upper River Segment of
the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. ...................................................................................................................................... 226
Figure 5.8-22. Mean plankton tow dry weight biomass estimates (mg/m2) from vertical tow net
samples (n=5) collected in July 2014 for sites within three lakes in the Upper River Segment of
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the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. ...................................................................................................................................... 226
Figure 5.8-23. Mean percent relative abundances of zooplankton taxa density and biomass from
vertical tow net samples (n=5) collected in July 2014 for sites within three lakes in the Upper
River Segment of the Susitna River for the River Productivity Study. ...................................... 227
Figure 5.8-24. Depth profiles for temperature and photosynthetically active radiation (PAR)
light levels recorded in July 2014 for sites within three lakes in the Upper River Segment of the
Susitna River for the River Productivity Study. “*” indicates measurements were limited by
probe cable length (approx. 96 ft), and did not reach the lake bottom. ...................................... 228
Figure 5.8-25. Depth profiles for dissolved oxygen (DO) and percent dissolved oxygen recorded
in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study. “*” indicates measurements were limited by probe cable length
(approx. 96 ft), and did not reach the lake bottom. ..................................................................... 229
Figure 5.8-26. Depth profiles for general and specific conductivity recorded in July 2014 for
sites within three lakes in the Upper River Segment of the Susitna River for the River
Productivity Study. “*” indicates measurements were limited by probe cable length (approx. 96
ft), and did not reach the lake bottom. ........................................................................................ 230
Figure 5.8-27. Depth profiles for pH and Oxidation Reduction Potential (ORP) recorded in July
2014 for sites within three lakes in the Upper River Segment of the Susitna River for the River
Productivity Study. “*” indicates measurements were limited by probe cable length (approx. 96
ft), and did not reach the lake bottom. ........................................................................................ 231
APPENDICES
Appendix A: Additional Tables
Appendix B: Site-specific Sample Collection Locations
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LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
13C Carbon-13 isotopic signature, reported in parts per thousand (per mil, ‰)
15N Nitrogen-15 isotopic signature, reported in parts per thousand (per mil, ‰)
°C degrees Celsius
°F degrees Fahrenheit
µg micrograms
µm micrometer
µS microsiemen
‰ parts per thousand (per mil)
ADF&G Alaska Department of Fish and Game
AEA Alaska Energy Authority
AFDM ash free dry mass
AMSL Above Mean Sea Level
ANCOVA Analysis of Covariance
BOM benthic organic matter
C carbon
CIRWG Cook Inlet Regional Working Group
cm centimeter
cm2 square centimeter
Cmax maximum consumption rate
COC chain of custody
CP capture probability
CPOM coarse particulate organic matter
df degrees of freedom
EMAP Environmental Monitoring and Assessment Program
EPT Ephemeroptera, Plecoptera, and Trichoptera, insect orders of typically sensitive taxa
DO dissolved oxygen
DOC dissolved organic carbon
FA Focus Area
FBOM fine benthic organic matter
FERC Federal Energy Regulatory Commission
FFG functional feeding groups
FL Fork length
FPOM fine particulate organic matter
ft foot (feet)
ft2 square feet
ft3 cubic foot (feet)
g gram
GRP growth rate potential
H’ Shannon-Wiener diversity index, calculated to represent diversity
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Abbreviation Definition
HCl hydrochloric acid
HDPE high-density polyethylene
HSC habitat suitability curve
HSI habitat suitability index
hyp hypothesis
in inch(es)
in2 square inch(es)
IP Implementation Plan
ISR Initial Study Report
J joule
J’ Pielou’s J’, an index of community evenness
Kd light extinction coefficient
L liter(s)
LWD large woody debris
M molar, molarity (= moles of solute per liter of solution)
m2 square meter(s)
MANCOVA Multivariate analysis of covariance
MDN marine-derived nutrients
mg milligram(s)
MixSIAR A Bayesian stable isotope mixing model
mm millimeter(s)
mV millivolt(s)
N nitrogen
NAWQA National Water-Quality Assessment
NO2 nitrite
NO3 nitrate
NTU nephelometric turbidity unit
OHWM ordinary high water mark
OM organic matter
ORP Oxidation-Reduction Potential
oz ounce(s)
p P-value or calculated probability. The estimated probability of rejecting the null hypothesis
(H0) of a study question when that hypothesis is true.
PAR photosynthetic active radiation
pCO2 partial pressure of carbon dioxide
pH measure of how acidic/basic water is, range goes from 0 – 14.
PIT-tag Passive Integrated Transponder tags used to individually identify animals and monitor their
movements.
PMCMR Pairwise Multiple Comparisons of Mean Rank
PRM Project River Mile
QAPP quality assurance project plan
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Abbreviation Definition
QA/QC quality assurance/quality control
RD reaction distance
RM river mile
RP River Productivity
RSP Revised Study Plan
SD standard deviation
SIA stable isotope analysis
SL standard length
SPD Study Plan Determination
spp. species
SRP Soluble Reactive Phosphorus
TEF trophic enrichment factors
TKA Talkeetna River
TKN Total Kjeldaho Nitrogen
TP Total Phosphorus
UAF University of Alaska-Fairbanks
U.S. United States
USEPA United States Environmental Protection Agency
USGS United States Geological Survey
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1. INTRODUCTION
On December 14, 2012, Alaska Energy Authority (AEA) filed its Revised Study Plan (RSP) with
the Federal Energy Regulatory Commission (FERC or Commission) for the Susitna-Watana
Project, FERC Project No. 14241, which included 58 individual study plans (AEA 2012).
Included within the RSP was the River Productivity Study, Section 9.8. RSP Section 9.8 focuses
on collecting baseline data to assist in evaluating the effects of Project-induced changes in flow
and the interrelated environmental factors upon the benthic macroinvertebrate and algal
communities in the Middle and Upper Susitna River. On April 1, 2013 FERC issued its final
study determination (April 1 Study Plan Determination [SPD]) that included approval for RSP
Section 9.8 with modifications (FERC 2013).
In 2013 and 2014, AEA adopted the FERC recommended modifications and implemented them
with the variances presented in the Initial Study Report (ISR) for Study 9.8 (AEA 2014a). The
ISR for Study 9.8, River Productivity, presented activities required to complete the Study Plan
(ISR Part C, Section 7.1; AEA 2014a). This year-end report presents an update on activities
conducted during 2014. Field work in 2014 was largely focused on data collection to support the
needs of the trophic modeling and stable isotope analysis objectives of the study. This report
includes a discussion of the following four field activities that AEA completed in 2014 (ISR Part
C, Section 7.2; AEA 2014a):
1. Estimate drift of invertebrates (RSP Section 9.8.4.5; AEA 2012), as modified in ISR Part
C Section 7.1.2.2 (AEA 2014a);
2. Conduct trophic modeling and stable isotope analysis (RSP Section 9.8.4.7; AEA 2012)
as modified in ISR Part C Section 7.1.2.4 (AEA 2014a);
3. Analyze fish diet (RSP Section 9.8.4.11; AEA 2012) as modified in ISR Part C, Section
7.1.2.5 (AEA 2014a);
4. Measure productivity in selected Susitna River tributaries and lakes above Devils
Canyon, as described in ISR Part C, Section 7.1.2.7 (AEA 2014a).
Field data collection efforts in 2014 associated with items 1 – 3 above, were briefly summarized
in the 2014 Field Season River Productivity Progress Report Technical Memorandum (R2 and
UAF 2014a) in September 2014, and are elaborated upon herein. This report also contains
summaries of the laboratory analyses for 2013 samples completed and presented in the 2013
Initial River Productivity Results Technical Memorandum (R2 and UAF 2014b) in September
2014, and of the Fish Diet Sample Size Sufficiency Analysis Technical Memorandum (UAF and
R2 2014) in December 2014. Finally, the report presents preliminary results of the 2013 data
sets that were not available for inclusion in the 2013 technical memorandum. These data
include: benthic macroinvertebrates on large woody debris (RSP Section 9.8.4.5; AEA 2012),
adult emergence samples, and the organic matter estimates from benthic and drift samples.
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2. STUDY OBJECTIVES
The study objectives for Study 9.8, River Productivity, were established in the Study Plan (RSP
Section 9.8.1). The overarching goal of this study is to collect baseline data to assist in
evaluating the effects of Project-induced changes in flow and the interrelated environmental
factors (temperature, substrate, water quality) upon the benthic macroinvertebrate and algal
communities in the Middle and Lower Susitna River. Individual objectives that address this goal
and were accomplished in 2014:
Synthesize existing literature on the impacts of hydropower development and operations
(including temperature and turbidity) on benthic macroinvertebrate and algal
communities. This objective was completed and is included in the ISR Part A, Appendix
A (AEA 2014a).
Characterize the pre-Project benthic macroinvertebrate and algal communities with
regard to species composition and abundance in the Middle and Lower Susitna River.
Estimate drift of benthic macroinvertebrates in selected habitats within the Middle and
Lower Susitna River to assess food availability to juvenile and resident fishes.
Conduct a feasibility study in 2013 to evaluate the suitability of using reference sites on
the Talkeetna River to monitor long-term Project-related change in benthic productivity.
Conduct a trophic analysis to describe the food web relationships within the current
riverine community within the Middle and Lower Susitna River.
Characterize the invertebrate compositions in the diets of representative fish species in
relationship to their source (benthic or drift component).
Characterize organic matter resources (e.g., available for macroinvertebrate consumers)
including coarse particulate organic matter, fine particulate organic matter, and
suspended organic matter in the Middle and Lower Susitna River.
Estimate benthic macroinvertebrate colonization rates in the Middle Susitna Segment
under pre-Project baseline conditions to assist in evaluating future post-Project changes
to productivity in the Middle Susitna River.
Characterize the pre-Project benthic macroinvertebrate communities, with regard to
species composition and abundance, and algal production in selected Susitna River
tributaries and lake systems located above Devils Canyon.
3. STUDY AREA
As established by the Study Plan (RSP Section 9.8.3; AEA 2012), the River Productivity Study
conducted field sampling in 2014 throughout the Middle Segment and upper portion of the
Lower Segment on the Susitna River (Figures 3-1 and 3-2). The Middle Susitna River Segment
encompasses the 85-mile section of river between the proposed Watana Dam site and the
Chulitna River confluence, located at Project River Mile (PRM) 102.4 (River Mile [RM] 98.6)
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(Figure 3-1). Sampling has been conducted at various distances from the proposed dam site to
document longitudinal variability, and estimate the effects that the proposed Project will have on
benthos in the river system downstream. The Lower Susitna River Segment, defined as the
approximate 102-mile section of river between the Three Rivers Confluence and Cook Inlet
(Figure 3-2), has been sampled in this study to document the current conditions within the upper
portions of the segment, and help to understand any potential Project operation effects on benthic
communities within the mainstem Susitna River below the Three Rivers Confluence. The
Talkeetna River is an approximate 85-mile long tributary of the Susitna River, joining with the
Susitna and Chulitna rivers at the Three Rivers Confluence (Figure 3-1). Sampling activities on
the Talkeetna River in 2013 only, and sites were located approximately 8.5 – 9 miles upstream
from the mouth, as an effort to assess the feasibility of the Talkeetna River as a reference site for
post-Project monitoring activities.
In addition, the River Productivity Study team collected benthic macroinvertebrate and algal
samples once during the summer of 2014 within nine selected tributaries located above Devils
Canyon within the Middle and Upper Susitna River basin (Figure 3-3) and three lakes (Tyone
Lake, Susitna Lake, and Lake Louise) within the Tyone River drainage basin in the Upper
Susitna River basin (Figures 3-3 and 3-4). This objective is a variance, as it is a proposed
modification described in ISR Part C, Section 7.1.2.7 (AEA 2014a).
4. METHODS AND VARIANCES IN 2014
This study employed a variety of field methods to build on the existing benthic
macroinvertebrate and algal community information in the Middle Susitna River. The following
sections provide brief descriptions of study site selection, sampling timing, the approach, and
methods that were used to accomplish each objective of this study.
4.1. River Productivity Implementation Plan
This study report includes a description of the sampling scheme consistent with the final
sampling scheme detailed in the River Productivity Implementation Plan (IP) filed with FERC
on March 1, 2013 (R2 2013a), with the exception of specific variances as described within each
section.
4.2. Site Selection
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.2.3.).
Sampling on the Susitna River was stratified by river segment and mainstem habitat type, as
defined in the Project-specific habitat classification scheme (e.g., main channel, tributary mouth,
side channel, side slough, and upland slough). Sampling occurred at five stations on the Susi tna
River, each station with three to five sites (establishing sites at all macrohabitat types present
within the station), for a total of 21 sites. In the Middle River Segment, two stations were located
between the dam site and the upper end of Devils Canyon, and two stations were located
between Devils Canyon and Talkeetna (Table 4.2-1; Figure 3-1). All stations established within
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the Middle River Segment were located at Focus Areas stablished by the Fish and Aquatic
Instream Flow Study (R2 2013b; R2 2013c), in an attempt to correlate macroinvertebrate data
with additional environmental data (flow, substrates, temperature, water quality, riparian habitat,
etc.) collected by other studies (e.g., Baseline Water Quality Study, Study 5.5), and for
macroinvertebrate habitat suitability curve and habitat suitability index (HSC/HSI) development.
Many of these Focus Areas were also used for collecting target fish species for trophic analysis
(RSP Section 9.8.4.7; AEA 2012).
To determine to what extent, if any, the Project operations may affect benthic communities, as
well as the influence that the two tributaries may have on those communities below the
confluence of the Three Rivers, one station was located in the upper portion of the Lower River
(Figure 3-2).
Data collection station and site locations are described below.
4.2.1. Middle River Stations / Focus Areas
Within the Middle River, each one of the four sampling locations was located within a Focus
Area (Table 4.2-1; Figure 3-1 and Figures 4.2-1 through 4.2-4). Two stations between the
proposed dam site and Devils Canyon were established in Focus Area (FA)-184 (Watana Dam)
and FA-173 (Stephan Lake Complex). Between Devils Canyon and Talkeetna, two stations were
established in FA-141 (Indian River) and FA-104 (Whiskers Slough).
FA-184 (Watana Dam) is located approximately 1.4 miles downstream of the proposed dam site
and provides a mainstem site and a side channel site within its 1-mile extent (Figure 4.2-1; Table
4.2-1). In order to meet the objective of sampling sites at 3 or more habitats, it was necessary to
move outside of the FA-184 (Watana Dam) to include a site at the mouth of Tsusena Creek. In
2014, a formal location for drift sampling above the mouth of Tsusena Creek was determined, as
opposed to using the mainstem site as was done in 2013. FA-173 (Stephan Lake Complex) is
located approximately 11.7 miles downstream of the proposed dam site and contains a complex
of main channel and off-channel habitats within a wide floodplain, thus representing the greatest
channel complexity within its geomorphic reach (MR-2; Figure 4.2-2). FA-173 (Stephan Lake
Complex) provided a mainstem site, a side channel site which also served as the above-tributary
mouth drift sampling location, a side slough site, an upland slough site, and a small tributary
mouth site within its 1.8-mile extent (Table 4.2-1). .
Below Devils Canyon, FA-141 (Indian River) and FA-104 (Whiskers Slough) were selected due
to the diversity of main- and off-channel habitats that they contained, and documented fish use in
and nearby these Focus Areas. FA-141 (Indian River) includes the Indian River confluence,
which is a primary Middle Susitna River tributary with high levels of fish use. FA-141 (Indian
River) provided a mainstem site, a tributary mouth site, a side channel site, and an upland slough
site, as well as a drift sampling location above the tributary mouth, within its 1.6-mile extent
(Figure 4.2-3; Table 4.2-1). FA-104 (Whiskers Slough) is located approximately 2.4 miles
upstream of the confluence of the Chulitna and Susitna rivers, making it the downstream-most
station in the Middle River for the River Productivity Study. This Focus Area contains the
confluence of Whiskers Creek, side channels, and side slough habitats that have been
documented as supporting juvenile and adult fish use. FA-104 (Whiskers Slough) provided a
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main channel site, a side-channel site, a side slough site which also served as the above-tributary
mouth drift sampling location, an upland slough site, and a tributary mouth site within its 1.2-
mile extent (Figure 4.2-4; Table 4.2-1).
4.2.2. Lower River Station
Within the Lower River, one study station, with four sampling sites was established in
conjunction with Fish Distribution and Abundance (Study 9.6) sampling activities on the Lower
Susitna River around the Montana Creek mouth area (Table 4.2-1, Figures 3-2 and 4.2-5). This
Lower River station (River Productivity Station 81 [RP-81] [Montana Creek]) was located within
a 1.2-mile reach beginning approximately 21 miles downstream of the confluence with the
Chulitna and Talkeetna rivers. This area was complex, with split channels, side channels, upland
sloughs, and tributary mouths (Figure 4.2-5). Four sites were established at Station RP-81
(Montana Creek) including: 1) a mainstem site, 2) a side channel site, 3) an upland slough site,
and 4) a tributary mouth site, with an additional drift sampling location above the mouth of
(Table 4.2-1).
4.2.3. Variances
4.2.3.1. Site Selection in the Middle and Lower Susitna River
The methods for characterizing pre-Project benthic macroinvertebrate and algal communities in
the Middle and Lower Susitna River were conducted as in 2013, at sites as described in the Study
Plan except for those changes detailed as variances in ISR Part A, Section 4.2.4 (AEA 2014a),
which include: 1) moving the Lower River site from Trapper Creek to Montana Creek, which
had no effect on any of the study objectives, as it establishes one study station within the Lower
River Segment (ISR Section 4.2.4.1); 2) replacing the upland slough sites at FA-173 (Stephan
Lake Complex) with a small unnamed tributary mouth (ISR Section 4.2.4.2), which had no effect
on accomplishing the study objectives. Lack of permission to access Cook Inlet Regional
Working Group (CIRWG) land in 2013 prevented sampling at the upland slough site. However,
in 2014, land access for CIRWG lands was permitted, and this upland slough site was sampled
(RP-173-5).
4.2.3.2. Tributaries and Lakes above Devils Canyon
In the ISR Part C, Section 7.1.2.7 (AEA 2014a), AEA proposed a modification “with the stated
objective to characterize the pre-Project benthic macroinvertebrate communities, with regard to
species composition and abundance, and algal production in selected Susitna River tributaries
and lake systems located above Devils Canyon.” In July 2014, nine Susitna River tributaries and
three lake systems were selected based on historic estimates of salmon production potential
provided in Barrick et al. (1983). The three lakes were all located within the Tyone River
system. The nine tributaries that AEA sampled in 2014 were selected to ensure representation
from habitats that connect to each of the three upper river reaches that would be subject to
different potential effects: two selected tributaries drain into the mainstem Susitna River within
the reach below the proposed dam site and upstream of Devils Canyon, four tributaries drain into
the reach that would be inundated by the proposed reservoir, and three tributaries drain into the
reach upstream of the proposed reservoir (Table 4.2-2).
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Within the Middle and Upper River basins, one site was established on each of nine selected
tributaries located above Devils Canyon in the Middle and Upper Susitna River basin (Table 4.2-
2, Figure 3-3). For tributaries that would drain into the proposed reservoir inundation zone,
sampling was conducted near the upper extent of known Chinook presence (approximately 3,000
feet [ft] above mean sea level [AMSL]). For tributaries outside the proposed reservoir
inundation zone, sampling was conducted between the mouth of the tributary and either 3,000 ft
AMSL or the downstream-most fish barrier. In addition, three lakes (Tyone Lake, Susitna Lake,
and Lake Louise) were sampled once during the summer period to characterize the productivity
of these lacustrine habitats under the current, baseline condition. Each lake, due to their large
size, was stratified into three sampling sites in relation to the orientation to the lake outlet (upper,
middle, lower), as well as representative of the range of available depths (shallow, mid-depth,
deep) within each lake (Figure 3-4).
4.3. Characterize the Pre-Project Benthic Macroinvertebrate and
Algal Communities with Regard to Species Composition and
Abundance in the Middle and Lower Susitna River
No field work was conducted for this objective in 2014; for 2013, lab analysis for algae was
presented in the ISR (ISR Part A, Section 5.2; AEA 2014a). However, 2013 lab analysis for
several macroinvertebrate sample sets was completed, post filing of the ISR. Thus, the results
for macroinvertebrates were presented in 2013 Initial River Productivity Results Technical
Memorandum (R2 and UAF 2014b) in September 2014. In 2014, additional analysis was also
completed on the 2013 results of adult emergence traps and macroinvertebrates collected from
woody debris; these results are presented in Section 5.1 of this report.
4.3.1. 2013 Field Collection
Emergence trap collection methods were conducted as described in the ISR Part A, Section 4.4.1.
(AEA 2014a). Additional data review and analysis since the ISR showed a total of 65 collection
visits were made to retrieve and reset emergence trap samples over the course of the 2013 open-
water season. A total of 47 samples were collected from the 20 study sites and submitted to the
taxonomy laboratory in 2013 (Table 4.3-1). These totals supersede those given in Table 4.4-3 in
the ISR (Part A, Section 4.4.1.; AEA 2014a). Consistent with the ISR, a loss of 19 samples was
recorded due to a number of disturbances, including bear damage, boat traffic, and fluctuating
flow conditions.
Of the 47 samples retrieved, 27 samples were collected from traps that were intact and appeared
undisturbed; however, 20 samples were noted to be either damaged by wildlife, or stranded on
the shoreline due to receding water levels or by boat traffic (Table 4.3-2). The sample bottles of
these 20 disturbed samples still contained ethanol preservative with specimens, and were thus
retained as samples; however, their exact sampling durations are unknown, as they were found
out of the water at the time of retrieval. For purposes of reporting, sample metrics were
calculated assuming the full sampling duration.
Sampling methods for large woody debris (LWD) in the Susitna River were conducted as
described in the ISR Part A, Section 4.4.1. (AEA 2014a). Pieces of LWD were not prevalent at
all sites. A total of 155 samples were collected from 16 of the 20 sites in 2013 (ISR Part A,
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Section 4.4.1.; AEA 2014a). Pieces of wood were mostly located in tributary mouths and off-
channel macrohabitats; main channel sites rarely provided suitable LWD. Size distribution of
available woody debris pieces sampled shows that a majority (84.5 percent) were between 1- to
4-inches in diameter; only 11.6 percent of those suitable pieces found and processed were above
the defined 4-inch diameter for LWD (Figure 4.3-1).
4.3.2. Macroinvertebrate Metrics
Upon receipt of data results, the taxonomic composition of each sample was used to generate a
taxa-abundance matrix. The matrix was reviewed and adjusted for different levels of taxonomy.
When identifying macroinvertebrates, some specimens were either too immature or too damaged
for identification at the genus-level, and could only be assigned to a higher taxonomic level (e.g.,
family, subfamily, order). For instance, a sample may contain individuals identifiable only to the
mayfly family Baetidae, yet also contain individuals clearly identified to one or more genera
within this family (e.g., Baetis tricaudatus, Diphetor hageni). This situation can lead to inflated
estimates of the number of taxa in a sample.
To prevent the inflation of metrics, the abundances of these “parent” taxa were distributed
proportionately among their composite taxa. This apportioning is similar to the method used by
the United States Geological Survey (USGS) National Water-Quality Assessment (NAWQA)
studies to correct for “ambiguous taxa” (Cuffney et al. 1997). The abundances of “parent” taxa
(orders, families) were retained in analysis when there were no composite taxa identified in the
sample.
After applying the corrective measures used in preparing the taxa-abundance matrix, the data
were used to calculate a number of descriptive metrics commonly used in aquatic ecological
studies. These metrics were classified as abundance measures, richness measures, composition
measures, and functional feeding groups.
4.3.2.1. Abundance Measures
Macroinvertebrate abundance is represented by density, which is the total number of individuals
collected in a unit area. Subsample enumerations were expanded to provide a density estimate
(e.g., individuals/m²) for each sample.
4.3.2.2. Richness Measures
Metrics used to describe macroinvertebrate species richness include: taxa richness,
Ephemeroptera Plecoptera Trichoptera (EPT) taxa, Chironomid taxa, diversity, and evenness.
Taxa richness is the number of different types, or taxa, of invertebrates occurring in a given
sample. This metric is reported for individual sampling efforts, such as emergence traps (Section
5.1.1.1.) and composite D-net sweeps (Section 5.8.2.1.), and is used for overall summaries of
samples collected at each site during the study year. When considering a collection of replicate
samples at a site, two different taxa richness values are generated for this report:
During an individual sampling event (Spring, Summer, Fall), the mean taxa richness is the
average number of taxa collected from the replicate samples collected at a site, not the site’s total
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taxa richness. By averaging the taxa richness of the samples, the influence of rare taxa is
minimized, thus reducing the taxa richness score.
The total taxa richness for a site is simply a tally of all unique taxa collected at a site during an
individual sampling event, utilizing all collected samples. Thus, the occurrence of rare taxa is
given a weight equal to common taxa. As a result, total taxa richness indicates larger estimates
of taxa richness than mean taxa richness. While total taxa richness may not lend itself to
statistical analysis in the short-term study, it provides a measure of contrast between sites, and
may become statistically useful in the long-term program.
EPT taxa is the number of taxa from the insect orders of Ephemeroptera (mayflies), Plecoptera
(stoneflies), and Trichoptera (caddisflies). Following protocols from numerous state and federal
agencies, taxa richness values were calculated separately for each order. Both mean and total
EPT taxa count values were determined.
Chironomid taxa is the number of taxa from the insect family Chironomidae (midges, Order =
Diptera). Because Chironomidae are typically dominant in Alaskan streams (Oswood 1989),
identifications were made to genus level to fully reflect the taxonomic richness in the Susitna
River. This metric reflects the contribution of chironomids to the taxa richness measure. Both
mean and total chironomid taxa count values were determined.
Ecological diversity is a measure of community structure defined by the relationship between the
number of distinct taxa and their relative abundance. The Shannon-Wiener diversity index (H')
was calculated (log e) to represent diversity. This index usually lies between 1.5 and 3.5 for
ecological data. Higher index numbers indicate greater diversity, and the presence of a complex
ecological community. Diversity usually decreases with impaired habitat or water quality, or
increased disturbance. Pielou’s J’, an index of community evenness, was also calculated.
Values range from 0 to 1.0. Higher values indicate a more even spread in the community.
4.3.2.3. Composition Measures
The relative abundance of major taxonomic groups provides information on a stream
community’s structure and the relative contribution of the populations to the total fauna (Barbour
et al. 1999). Eight major taxonomic groups were used to describe the community structure in our
analysis: Ephemeroptera, Plecoptera, Trichoptera, Coleoptera (beetles), Chironomidae (midges),
Diptera (true flies other than midges), Other Insects, and Non-insects. Composition measures of
certain taxonomic groups are often used as indicators of impairment in streams. For example, an
increase in the relative abundance of non-insect taxa, or a decrease in the relative abundance of
EPT taxa, may indicate environmental stress in a stream. For emergence trap samples,
Hymenoptera and Hemiptera were added in place of Other Insects, due to the prevalence of
terrestrial insects in the samples. Additionally, the relative abundances of aquatic taxa and
terrestrial taxa were added for emergence trap sample results.
The EPT:Chironomid ratio is a ratio of the abundance of Ephemeroptera, Plecoptera,
Trichoptera in relation to chironomids. The ratio ranges from 0 to 1, with scores below 0.5
indicating more Chironomidae in the community.
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The percent dominant taxa metric is the relative abundance of the most abundant taxa in a
sample: the most abundant taxon, and the top three most abundant taxa, were calculated.
Disturbances usually cause the abundance of a few taxa to increase and an elevation of the
percent dominance of the most abundant taxa.
4.3.2.4. Functional Feeding Groups
Benthic macroinvertebrate taxa abundances were allocated into functional-feeding group
categories according to their preferred methods of gathering food, based on determinations of the
primary feeding mechanism by Barbour et al. (1999). The major functional-feeding groups used
in our analysis were: collector-gatherers, collector-filterers, scrapers, shredders, predators, and
parasites as defined by Cummins et al. (2008). All other functional feeding groups, and any
individuals with unclassified or unknown feeding mechanisms, were consolidated into a seventh
group, “Others.” Data are presented as a percent of the total sample abundance.
4.4. Estimate Drift of Invertebrates in Selected Habitats within the
Middle and Lower Susitna River to Assess Food Availability to
Juvenile and Resident Fishes
In 2014, AEA implemented the field methods for the collection of drifting invertebrates as
described in the Study Plan (River Productivity IP Section 2.1, R2 2013a; FERC 2013) with the
exception of variances explained below (Section 4.4.1). Invertebrate drift sampling for 2014 was
conducted in support of trophic analysis and fish diet sampling efforts at all sites within the five
established sampling stations to allow for comparisons between the drift component and
availability of invertebrates for fish predation. Three sampling events were conducted from June
through October in 2014 to capture seasonal variation in community structure and productivity.
The timing of events was influenced by availability of open water for sampling. Information on
the specific sampling timing is provided in Table 4.4-1.
Sampling was conducted in fast-water habitats, when they were present, within all established
sites (Tables 4.2-1 and 4.4-2). In addition, at all tributary mouth sites, a drift net pair was
deployed upstream of the site, to collect information on the relative contribution of tributaries to
fish prey resources in the mainstem Susitna River. A total of 108 drift samples were taken
during the 2014 field season (Table 4.4-2). The use of drift nets is not advised with currents less
than 0.16 feet per second (0.05 meters per second); thus, a plankton tow net (243-micrometer
(µm) mesh net with a 8-inch opening) was used at still water sites, taking five replicate
horizontal tows along transects across the channel. A total of 105 plankton tows were collected
from 9 of the 21 sites (Table 4.4-2).
Invertebrate drift and plankton tow samples were shipped to and processed by Ecoanalysts, Inc.
(Moscow, Idaho) using methods similar to those used for benthic samples (Barbour et al. 1999;
Major and Barbour 2001). Organic matter (OM) content from drift samples was retained and
analyzed by size (coarse and fine particulate OM) as discussed in Section 4.8. Drift results for
2014 are presented in Section 5.2 of this report. Data received was prepared for benthic
macroinvertebrate samples as detailed in Section 4.3. Density was measured by volume, per
cubic foot, and all metrics dependent upon density estimates reflect this as well. For
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composition measures, zooplankton was broken out from Non-insects, due to its prevalence in
plankton tow samples.
Lab analysis for the 2013 data collected was completed post-ISR filing in June 2014, and results
were presented in the 2013 Initial River Productivity Results Technical Memorandum (R2 and
UAF 2014b) in September 2014.
4.4.1. Variances
The methods for estimating drift of invertebrates (RSP Section 9.8.4.5; AEA 2012) were
employed as described in the Study Plan with the exception of the variances implemented in
2013, as described in ISR Part A, Section 4.5.1 (AEA 2014a) which include: 1) collecting
plankton tows at 5 still water sites; and 2) estimating dry weights for macroinvertebrate taxa
using length-weight relationship data from UAF as opposed to direct oven-dried biomass
weights.
4.5. Conduct a Feasibility Study in 2013 to Evaluate the Suitability
of Using Reference Sites on the Talkeetna River to Monitor
Long-term Project-related Change in Benthic Productivity
No field work was conducted for this objective in 2014. However, 2013 lab analysis was
completed post-ISR filing in June 2014, and results were presented in 2013 Initial River
Productivity Results Technical Memorandum (R2 and UAF 2014b) in September 2014.
4.6. Conduct a Trophic Analysis, Using Trophic Modeling and
Stable Isotope Analysis, to Describe the Food Web
Relationships in the Current Riverine Community within the
Middle and Lower Susitna River
4.6.1. Develop a Trophic Model to Estimate How Environmental Factors and
Food Availability Affect the Growth Rate Potential of Focal Fish Species
under Current and Future Conditions
In 2014, AEA implemented field methods as described in the Study Plan (River Productivity IP
Sections 2.10.1; R2 2013a; FERC 2013) with variances and one modification, the addition of
Arctic Grayling as a target species for the trophic analysis, as detailed in ISR Part C Section
7.1.2.4 (AEA 2014a). To determine how water temperature, food availability, and food quality
influence the growth of juvenile salmon and resident stream salmonids, field data from the Study
of Fish Distribution and Abundance in the Middle and Lower Susitna River (Study 9.6), and this
River Productivity Study was analyzed using a bioenergetics approach. This analysis allowed
comparisons of observed growth rates, estimated consumption rates, and estimated growth
efficiency (i.e., the grams [g] of growth achieved per g of food consumed) among different
habitats under the environmental conditions observed during 2013 and 2014. The inputs to the
bioenergetics models were growth (seasonal weight-at-age), water temperature, diet composition,
and the energy density of prey of each prey category.
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4.6.1.1. Observed fish growth rates
Growth rates were determined by aging scales using methods as described in ISR Part A Section
4.7.1. (AEA 2014a). Fish ages were determined using scales and temporal length distribution
data (DeVries and Frie 1996, Isely and Grabowski 2007). All fish sampled in this study were
aged, except for a small number for which all scales were regenerated or otherwise unreadable.
Ages were assigned based on the presence of annuli and the number of circuli. Length-
frequency data were used to determine the size of age-0 Chinook and Coho salmon during the
spring sampling events. During Sampling Event 1 (Spring) in both years, the size range of fish
sampled by the River Productivity Study (≥ 50 millimeter [mm] fork length [FL]) only partially
overlapped with the size distribution of age-0 Chinook and Coho salmon, based on examination
of the length-frequency distributions of these species sampled by the Fish Distribution and
Abundance in the Middle and Lower River Studies within the study area of the River
Productivity Study (Fig 5.4-1). Thus, the modal size of this age class was determined from the
length-frequency distributions. The modal fork length in each year was converted to wet weight
(W, g) for input to the model using length-weight relationships developed for juvenile Chinook
and Coho salmon:
W = 5.94 x 10-6 FL3.13 (n = 10,418, r2 = 0.96, p < 0.0001), (1)
in the Middle and Lower Susitna River based on the combined length and weight data collected
in 2013 and 2014 by the River Productivity and Fish Distribution and Abundance in the Middle
and Lower River Studies. These weight data were used as the starting points for simulations of
age-0 Chinook and Coho salmon during early summer.
The mean weight at age was determined for all other age-classes and seasons based on age-
length relationships from fish aged by scales. Weight data were analyzed statistically to test for
differences between years and among habitat types after taking date into account. For each
salmon species and age class, an Analysis of Covariance (ANCOVA) model was fit including a
Julian date as a covariate and main effects of year and habitat as well as all possible interactions.
These models were refined using backwards selection, iteratively removing the least significant
term until all remaining terms were significant, based on an alpha level of 0.05 (Kutner et al.
2005). Based on these results, the seasonal weight-at-age data were pooled among habitats that
did not differ statistically. This approach highlighted meaningful differences in growth among
habitat types, while enhancing sample sizes within modeled groups to reduce any potential
effects of random variability. Sample sizes for Arctic Grayling and Rainbow Trout were not
sufficient for statistical comparisons of seasonal weight-at-age among habitats, partly because
the available sample size was spread across larger numbers of age classes.
4.6.1.2. Bioenergetics modeling
Field data were compiled to generate growth, temperature, and diet composition inputs for
bioenergetics model simulations representing two periods in each year early summer,
representing growth between the spring and summer sampling events, and late summer,
representing growth between the summer and fall sampling events. The early summer
simulations corresponded to calendar days June 21 through August 20, 2013 (59 days) and June
14 through August 13, 2014 (57 days). The late summer simulations corresponded to calendar
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days August 21 through September 30, 2013 (34 days) and August 14 through September 23,
2014 (47 days). The start and end dates corresponded to the midpoints of each sampling event.
Hourly water temperatures were recorded by submerged temperature loggers deployed at all
sampling sites. Temperature loggers were deployed during Sampling Event 1 (Spring) and were
retrieved during Sampling Event 3 (Fall). Diet composition was determined from stomach
contents (Section 5.5). For modeling purposes, all diet items were grouped into five categories:
aquatic life-stages of freshwater-derived prey (such as chironomid larvae and pupae), terrestrial
life-stages of freshwater-derived prey (such as adult chironomid midges), terrestrial invertebrates
(such as ants and caterpillars), fish and non-salmonid fish eggs, and salmon eggs. We estimated
the energy density (Joule [J]/g wet weight) of these categories as 3,365 for aquatic life-stages of
freshwater-derived prey (McCarthy et al. 2009), 4,225 for terrestrial life-stages of freshwater-
derived prey (McCarthy et al. 2009), and 5,250 for terrestrial invertebrates (McCarthy et al.
2009), 5,235 for fish and non-salmonid fish eggs, based on the mean size of fish prey found in
stomach contents (27 mm FL, 0.2 g) and a size-based energy density relationship for sockeye
salmon (Beauchamp et al. 1989), and 9,000 for salmon eggs (Armstrong 2010).
Using these input data, Wisconsin bioenergetics models (Hanson et al. 1997) were used to
estimate the consumption rate (g wet mass / day) of prey by juvenile Chinook Salmon and Coho
Salmon during the spring-summer and summer-fall intervals between sampling events. The
models were implemented in the program R (R Core Team 2015) using custom code (A. G.
Hansen, University of Washington and E. R. Schoen, University of Alaska Fairbanks,
unpublished) that replicated the standard Fish Bioenergetics 3.0 software package (Hanson et al.
1997) in a scripted framework that facilitated running repeated simulations for the sensitivity
analysis. Bioenergetics models used physiological parameters developed for Chinook Salmon
(Stewart and Ibarra 1991; Plumb and Moffitt 2015) and Coho Salmon (Stewart and Ibarra 1991).
The models iteratively adjusted the ration size of simulated fish, expressed as a proportion P of
the theoretical maximum consumption rate (Cmax), until the simulated growth equaled the
observed growth. Lower values of P (near zero) indicated that growth was limited by low food
intake, while higher values near 1 indicated that feeding rates were high and growth was mostly
limited by thermal constraints on digestion and metabolism or by the quality of food. Growth
efficiency (g total growth / g total consumption) was computed for each simulation to indicate
the percent of energy intake that was allocated to growth as opposed to metabolism and waste.
These metrics were then compared to determine whether growth was limited primarily by water
temperature, food consumption, or food quality in the study area, and whether these limiting
factors differed among years, seasons, or habitats (McCarthy et al. 2009).
The growth rates of age-1 Chinook Salmon and age-2 Coho Salmon were not modeled because
nearly all fish in these age-classes migrated out of the study area after Sampling Event 1
(Spring). Arctic Grayling and Rainbow Trout sample sizes were not sufficient to determine
seasonal growth rates, so these species were not modeled.
4.6.1.3. Growth rate potential modeling
In addition to the descriptive bioenergetics analysis described above, a growth rate potential
(GRP) analysis was evaluated as a potential prospective approach for predicting fish growth rates
under changing environmental conditions. GRP models were developed for age-1 Coho Salmon,
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for which detailed foraging model parameters were available (Piccolo et al. 2008). Model
parameters were also available for age-1 Rainbow Trout (Piccolo et al. 2008), but this species
was not modeled in this study because very few age-1 Rainbow Trout were captured in the study.
The GRP models linked a simple drift foraging model based on the model of Hughes and Dill
(1990) to a Wisconsin bioenergetics model (Stewart and Ibarra 1991).
The drift foraging model estimated the consumption rate (g / day) of a drift-feeding age-1 Coho
Salmon at each site during each sampling event. The model assumed that fish would detect all
prey passing within a given reaction distance (RD) of their feeding position, and that they would
successfully capture and consume some fraction of these prey defined by a capture probability
(CP). The model estimated RD and CP based on water velocity-dependent relationships derived
from laboratory feeding trials using wild, age-1 (70-80 mm FL) Coho Salmon from the Situk
River, Alaska (Piccolo et al. 2008). These foraging parameters were applied in the current study
to estimate Coho Salmon feeding rates based on field measurements of water velocity and drift
invertebrate biomass density. The experiments of Piccolo et al. (2008) were conducted in clear
water conditions (turbidity = 0.3 nephelometric turbity units [NTU]), so the parameters were
adjusted to account for the effects of elevated turbidity levels on foraging rates in the Susitna
River. No turbidity-dependent reaction distance relationship was available specifically for Coho
Salmon, so a declining log-linear relationship between RD and turbidity for juvenile Chinook
Salmon (Gregory and Northcote 1993) was applied. This relationship was transformed to predict
the percent reduction in RD under a given turbidity level T, relative to the maximum RD that
would be predicted under clear-water conditions (RDmax):
RD = RDmax (1 – 0.42 log T) (2)
The model was only applied at sites for which the water velocity was at least 0.95 ft per second
(0.29 m / second), because juvenile Coho Salmon did not consistently hold station and drift feed
at lower velocities during feeding experiments (Piccolo et al. 2008). Salmon were assumed to
feed continuously during daylight hours (Hughes and Dill 1990; Nislow et al. 2000). The
duration of daylight (including civil twilight) was determined for the midpoint of each sampling
period using data from the United States (U.S.) Naval Observatory Astronomical Applications
Dept. (http://aa.usno.navy.mil/cgi-bin/aa_rstablew.pl).
The resulting consumption rates were input to a bioenergetics model for Coho Salmon with an
initial body size specified as 5.3 g (representing 80 mm FL), a generic dietary energy density
(3800 J / g, representing a mix of aquatic and terrestrial invertebrates [McCarthy et al. 2009]),
and a 7-day mean water temperature measured at the site during the given season. The output,
mass-specific growth rate potential (growth [g] / body weight [g] / day) was calculated for each
site and sampling event where adequate data were available. Growth rate potential values were
evaluated as a potentially useful metric of habitat quality integrating the effects of prey density,
temperature, water velocity, and turbidity. A sensitivity analysis was conducted to determine
which of these environmental factors were most influential in determining salmon growth rates.
Each variable was adjusted +/- 20% from the values measured in the field, and growth rate
potential was recalculated to determine model sensitivity.
Growth rate potential model results were compared to empirical growth data for sites and growth
intervals (early summer or late summer) for which 1) an adequate sample size of juvenile Coho
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Salmon (n ≥ 4) was collected in two consecutive sampling events to allow the estimation of an
observed growth rate for the interval between the events, and 2) growth rate potential models
were available for both sampling events, allowing estimation of growth-rate potential for the
interval. Only one site met these criteria, RP-141-1. Empirical growth rates and model-derived
growth rate potential estimates were available for both early summer and late summer 2013 at
this site. Due to the lack of corresponding data, the predictive power of the growth rate potential
approach was not evaluated statistically. Instead, the model predictions were examined
graphically.
Additionally, lab analysis of 2013 field samples was completed post-ISR filing in June 2014, and
results were presented in 2013 Initial River Productivity Results Technical Memorandum (R2
and UAF 2014b) in September 2014.
4.6.2. Conduct Stable Isotope Analysis of Food Web Components to Help
Determine Energy Sources and Pathways in the Riverine Communities
In 2014, AEA implemented field methods as described in the Study Plan (River Productivity IP
Sections 2.11; April 2013 SPD) with the exception of variances explained below (Section 4.6.3),
and with one modification, the addition of Arctic Grayling as a target species for the trophic
analysis, as detailed in ISR Part C Section 7.1.2.4 (AEA 2014a). To better understand the
trophic relationships in the Middle and Lower Susitna River, stable isotope sampling was
conducted at four stations; one in the Lower River (RP-81 [Montana Creek]) and three in the
Middle River (FA-104 [Whiskers Slough], FA-141 [Indian River], and FA-184 [Watana Dam])
(Table 4.2-1 and Figures 3-1 and 3-2). A total of 1,557 samples were analyzed for stable isotope
analysis (SIA) from multiple study components, including benthic macroinvertebrates, benthic
algae, benthic organic matter, invertebrates and organic matter in drift samples, emergent aquatic
insects, salmon carcasses, and fin clips from fish (Table 4.6-1). Samples were collected at all
sites within these four stations, for a total of 16 sites, in conjunction with other related sampling
efforts undertaken at each site/habitat type (Sections 4.4, 4.7, and 4.8).
For collection of stable isotope tissues from benthic macroinvertebrates and benthic organic
matter (BOM), qualitative sampling was conducted using either a modified Hess sampler or a
243-μm D-frame kick net (Figure 4.6-1). Three composite samples were collected from each
site, yielding a targeted wet weight of approximately 10 g (0.35 ounce [oz]) BOM, and 2 to 5 g
(0.07 to 0.17 oz) for each of four functional feeding groups of benthic macroinvertebrates.
Separation of macroinvertebrates from organic matter, identification, and sorting into feeding
groups was conducted using a dissecting microscope in the lab at the University of Alaska-
Fairbanks (UAF). Macroinvertebrates were sorted into functional feeding groups that each
comprised a single composited sample to be used for stable isotope analysis (Table 4.6-1). A
total of 589 benthic macroinvertebrate sample components and 144 benthic organic matter
sample components were analyzed in 2014.
For collection of the benthic algae component for stable isotope analysis at each site, three
composite samples representative of the algae assemblage present in each habitat type were
taken, targeting a wet weight of 10 g (0.35 oz). Each composite sample was collected by
thoroughly brushing the top and side surfaces of five haphazardly selected rocks and retaining
the loosened algal material for analysis in the lab at UAF. A total of 142 benthic algae sample
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components were analyzed in 2014 (Table 4.6-1).
For collection of stable isotope material from drifting invertebrates and organic matter (seston),
qualitative sampling was conducted using a pair of drift nets with 250-μm mesh (Figure 4.6-1).
Two composite samples were collected from each site where drift sampling could be conducted,
yielding a targeted wet weight of approximately 10 g (0.35 oz) seston, and 2 to 5 g (0.07 to 0.17
oz) for each composite sample of benthic macroinvertebrates. A total of 102 drift sample
components and 96 seston sample components were analyzed in 2014 (Table 4.6-1). All samples
were preserved in 70-percent ethanol and returned to UAF for further analysis.
For collection of stable isotopes from emerging adult aquatic insects, sample material was taken
from emergence traps that were deployed at two off-channel sites per focus area (Figure 4.6-1).
Off-channel sites were chosen for deployment in order to reduce damage and loss by boat wakes.
Traps were set for a period of between 2 and 4 days. Upon collection from traps, any
invertebrates present in the traps were transferred to a sample bottle, preserved in 70-percent
ethanol, and returned to UAF for analysis. A total of 61 emergent insect samples components
were analyzed in 2014.
Spawning salmon carcass tissue samples were collected as encountered between site RP-81
(Montana Creek) and FA-184 (Watana Dam) (Figures 3-1, and 3-2). A total of up to 40 tissue
samples per year from a combination of Pink, Chum, Coho, Sockeye, and Chinook salmon were
targeted for collection for stable isotope analysis of marine-derived nutrients (MDN). When and
where possible, tissue samples were taken from spawning salmon carcass tissues by excising 2 to
5 g (0.07 to 0.17 oz) of muscle tissue approximately 1 to 3 inches behind the dorsal fin. A total
of 9 carcasses were collected during summer and fall for stable isotope analysis (Table 4.6-1).
All samples were preserved in 70-percent ethanol and returned to UAF for further analysis.
Stable isotope samples were collected non-lethally from fish selected and sampled as part of the
fish diet analysis (Section 4.7) for targeted fish species (juvenile Chinook Salmon, Coho Salmon,
Arctic Grayling, and Rainbow Trout). A total of up to 8 fish per target species per site were
sampled, if present; a total of 445 fish samples were analyzed in 2014 (Table 4.6-1). Tissue
samples were obtained by clipping a small portion (at least 0.25 square centimeter [cm2] [0.04
in2]) of the caudal fin with sterilized sharp scissors. Caudal fin tissue regenerates rapidly and is
unlikely to affect the growth or survival of large fish; however it may cause a reduction in
survival for fish smaller than 50 mm (2 in) FL. Therefore, fish smaller than this size selected for
stable isotope sampling were euthanized, and used as a whole-fish sample. All samples were
preserved in 70 percent ethanol and returned to UAF for further analysis.
All sample types for stable isotope analysis were oven dried at 60 degrees Celsius (°C) (140
degrees Fahrenheit [°F]) to a constant weight and ground to a homogenous powder. Algae
samples were treated with 1 molar (M) hydrochloric acid (HCl) solution to remove inorganic
carbonates that may affect sample carbon-13 isotopic signature (13C) values. All invertebrate
samples, salmon carcass tissue, and salmon eggs were treated with a chloroform-methanol
solution to remove lipids from fatty tissues that typically have more variable and depleted 13C
signatures relative to other tissue types (Sotiropoulos et al. 2004), and that may ultimately affect
the comparability of isotopic values of samples with varying lipid content. Subsamples of
approximately 2.0-2.5 milligrams (mg) for algae, 0.3-0.4 mg for OM, and 0.2-0.4 mg for animal
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tissue were weighed to the nearest 0.001 mg on a micro- analytical balance and placed into tin
capsules. Samples were combusted and analyzed in an isotope-ratio mass spectrometer
interfaced with an elemental analyzer at the Alaska Stable Isotope Facility at UAF.
Results of stable isotope analysis will be used in conjunction with the bioenergetics model
(Section 4.6.1) and the fish diet analysis (Section 4.7) to describe and quantify the energy
pathways and trophic relationships supporting salmonid production in the food web of the study
area.
To characterize baseline isotopic variability, mean 13C values of benthic algae, benthic organic
matter, and seston organic matter were compared across macrohabitat types, along an upstream
to downstream continuum, and among seasons. Stable isotope ratios for all sample types were
tested for normality using the Shapiro-Wilk test. Many distributions were non-normal, so the
non-parametric Kruskal-Wallis H-test was used for all comparisons. If the differences in mean
13C values were statistically significant, the test was followed with the nonparametric Nemenyi
post-hoc comparisons test using the R package Pairwise Multiple Comparisons of Mean Rank
(PMCMR) (Pohlert 2014). Prior to conducting analysis on basal carbon sources, a
nonparametric multiple comparisons test was performed on carbon to nitrogen (C:N) ratios of
algae and terrestrial OM to evaluate possible cross-contamination between the two sample types.
Algae C:N ratios typically range from 8:1 (Thorp et al. 1998) to 12:1 (Wetzel 1983) and
terrestrial OM ranges from 45:1 to 50:1 (Wetzel 1983) or significantly higher than algae (Thorp
et al. 1998). Tests revealed that mean algae C:N ratios were significantly lower than that of
terrestrial OM (mean C:Nalgae = 8.7 ± 2.8 standard deviation [SD]; mean C:NOM = 29.8 ± 9.4
SD; H = 511.62, p < 0.001), indicating that the OM samples were relatively uncontaminated by
algae growth. For all tests, alpha was set at 0.05. Means are presented with ± 1 SD.
Multiple linear regressions were used to determine the role of terrestrial OM and algae in the
diets of the invertebrate collector, grazer, and shredder primary consumer groups. Because algae
13C can be highly variable within reaches and can often overlap with that of terrestrial OM
within a given site, using site-specific mixing models to estimate resource contributions to
invertebrate consumers would likely produce unacceptable error. Previous studies (Finlay 2001,
Bunn et al. 2003, Rasmussen 2010, Jardine et al. 2014) have used a gradient method where
spatial variation of source and consumer 13C is used to determine overall, watershed-scale
contributions of algae (or algae) and terrestrial OM to invertebrate primary consumers. To
understand large-scale energy flow to aquatic invertebrates, multiple linear regressions were
performed for site-specific mean 13C values of primary consumer feeding groups (collectors,
grazers, and shredders) and site-specific mean 13C values of their potential food sources (algae
and terrestrial OM) collected from all locations. Mean 13C values of terrestrial OM collected in
the stream benthos (-28.0 ± 1.4 part per thousand [‰]) and in seston samples (-27.8 ± 1.2‰) did
not differ significantly according to the non-parametric Kruskal-Wallis H-test (H = 11.98, p =
0.46), so these sample types were pooled as a single terrestrial OM food source. Sample material
from some consumer feeding groups was limited or not available at certain sampling events, so
all consumer 13C values across seasons. Each data point in the regressions therefore represents
the mean δ13C values of a consumer group and source (either algae or terrestrial OM) collected
from a particular site across all seasons when sample material was available. Because there is
little isotopic fractionation of organic carbon from prey to consumer (DeNiro and Epstein 1978),
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a slope coefficient close to 1 and a high r2 value indicates a strong reliance on a particular food
source (Finlay 2001; Jardine et al. 2014).
The relative contributions of freshwater, marine, and terrestrial prey to salmon diets were
estimated from stable isotope and stomach content data using the Bayesian stable isotope mixing
model, MixSIAR (Stock and Semmens 2013). This model uses isotopic values of consumers,
prey, and trophic enrichment factors as model inputs. MixSIAR estimates the probability
distributions of multiple prey contributions to consumers while accounting for the observed
variability in consumer, prey, and trophic enrichment isotopic values. The model also allows the
incorporation of prior information from another dataset, such as stomach content data, to further
refine estimates of prey contributions to a consumer (Moore and Semmens 2008; Parnell et al.
2010). Informative priors from stomach content data were incorporated in order to mitigate
potential temporal biases of these two methods and to obtain more precise estimates when prey
sources are isotopically similar. The posterior model outputs presented in this study are
therefore a combination of the priors and the maximum likelihood influence of the isotopic data,
where prey sources that are well-separated (less correlated) in isotopic space (nitrogen-15
isotopic signature (15N) vs. 13C) provide more useful information for the isotopic data to
override influence from priors (Moore and Semmens 2008). Conversely, when the prey sources
are isotopically more similar (highly correlated), priors may have more influence in the posterior
output (Moore and Semmens 2008). Prior values were calculated separately for each sampling
event by multiplying the diet proportion of each prey type (freshwater, terrestrial, or marine) by
the sample size of non-empty stomachs. Correlations between posterior estimates of diet
proportions are reported for diagnostic purposes in the discussion as Pearson’s product-moment
correlation coefficients (r).
To select appropriate trophic enrichment factors (TEF) for diet modeling, values from four
different literature sources (VanderZanden and Rasmussen 2001; Post 2002; McCutchan et al.
2003; and Trueman et al. 2005) were qualitatively evaluated relative to consumer isotopic
signatures after adjusting for trophic enrichments. These literature values were either based
primarily on data from aquatic consumers (Vander Zanden and Rasmussen 2001; Post 2002) or
specifically from salmonids (Trueman et al. 2005; McCutchan et al. 2003). Consumer values
were plotted against that of prey adjusted for each of the sets of TEF val ues separately to
determine if consumer values were within the mixing polygon (Parnell et al. 2010). Values from
Post (2002) (0.4 ± 1.3 for 13C and 3.4 ± 1.0 for 15N) were ultimately chosen because the
majority of plots evaluated showed that consumers fell within mixing polygons, whereas
adjusting for TEF values from the other literature sources resulted in fewer plots where
consumers were within mixing polygons.
To compare diet patterns among macrohabitat types, seasons, and reaches, a separate diet model
was run for each sampling event where fish were caught for both 2013 and 2014. While
MixSIAR allows for up to two covariates and a nested design template, the current version does
not simultaneously allow for multiple sets of informative priors to be defined for specific
consumer groups; therefore, at the expense of further quantifying variation between consumer
groups, separate models were run for each consumer group to more specifically define
informative priors from each group’s stomach content data. Overall, mean 13C values of all
aquatic invertebrate functional feeding groups (collectors, grazers, shredders, and predators)
were not significantly different (Kruskal-Wallis H-test; H = 5.23, p = 0.16); therefore, we
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combined these functional feeding groups into a single “freshwater” invertebrate prey type for
each sampling event for use in stable isotope mixing models. Terrestrial invertebrates were
absent in drift and benthic samples collected during some sampling events; in these cases, the
pooled isotopic signatures of terrestrial prey from other sampling events within the same reach
and season were used as a surrogate. The same marine source values were used for all models
within a year and consisted of any salmon carcass and egg samples collected across the entire
river. Proportional contributions of each prey type are reported as the mean of the posterior
distributions with 2.5 and 97.5% lower and upper credible intervals. All models were verified to
have converged using Geweke’s criterion and trace plots (Stock and Semmens 2013).
Additionally, lab analysis was completed on 2013 field samples and results were presented in
2013 Initial River Productivity Results Technical Memorandum (R2 and UAF 2014b) in
September 2014.
4.6.3. Variances
The methods for conducting the trophic analysis, using trophic modeling and stable isotope
analysis (RSP Section 9.8.4.7; AEA 2012), were conducted as in 2013, in accordance with the
Study Plan, with the exception of those changes detailed as variances in ISR Part A, Section
4.7.3 (AEA 2014a) which include: 1) increasing stable isotope site selection from the original
two stations (3 sites each) to four stations, resulting in sampling 16 sites total (ISR Part A,
Section 4.7.3.1; AEA 2014a); and 2) not utilizing macrohabitat-specific subcutaneous dye
marking to track movements of juvenile Chinook Salmon, Coho Salmon or rainbow trout less
than 60 mm long (ISR Part A, Section 4.7.3.2; AEA 2014a). In addition, the modification
proposed in the ISR Part C, Section 7.1.2.4. (AEA 2014a) to include Arctic Grayling juveniles
and adults as target species/lifestages, was conducted as part of the 2014 field collection efforts
for the trophic modeling and stable isotope analysis objectives.
4.7. Characterize the Invertebrate Compositions in the Diets of
Representative Fish Species in Relationship to their Source
(benthic or drift component)
AEA implemented field methods as described in the Study Plan (River Productivity IP Sections
2.7 and 2.8, R2 2013a; FERC 2013) with the exception of variances explained below (Section
4.7.1.), and the addition of Arctic Grayling as a target species for the trophic analysis, a
modification detailed in ISR Part C, Section 7.1.2.4 (AEA 2014a).
In support of the bioenergetics modeling (Objective 5, Section 4.6.1), stomach contents were
collected from all target species. Arctic Grayling and Rainbow Trout were provisionally
categorized as “small” or “large” with a breakpoint of 120 mm (4.7 in) fork length,
corresponding to the approximate onset of piscivory of Rainbow Trout in the study area in 2013.
The fish collections were coordinated with the Fish Distribution and Abundance in the Middle
and Lower Susitna River Study (Study 9.6.) and methods used for collecting fish specimens are
described in that study’s Initial Study Report (ISR Study 9.6).
Two fish sampling technicians accompanied the River Productivity crew during all sampling
events to each study site in order to fully overlap with invertebrate sampling efforts. Technicians
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employed multiple methods to sample target fish species including seine nets, fyke nets, minnow
traps, backpack electrofishing, and angling. Upon arrival at each study site, the appropriate gear
types were chosen and deployed depending on the conditions at each site. Up to 12 baited
minnow traps, up to two fyke nets, and seine nets were typically utilized within sites that were
characterized by relatively low water velocity such as upland slough and side slough
macrohabitat types. Seine nets, a backpacker electrofisher, and angling gear were typically
utilized to sample target species within tributary mouth, main channel, and side channel
macrohabitat types. Arctic Grayling were most common at main channel and side channel sites
within each Focus Area. Juvenile Chinook and Coho salmon were common in catches within
off-channel macrohabitat types at RP-81 (Montana Creek), RP-104 (Whiskers Slough), RP-141
(Indian River), and several Chinook Salmon juveniles were caught at main channel sites above
Devils Canyon at RP-173 (Stephan Lake Complex) and RP-184 (Watana Dam) during the Spring
sampling event. Small Rainbow Trout were rare or absent at all sampling sites (n = 8, Tables
4.7-1 through 4.7-3). Sampling efforts during 2014 resulted in a total catch of 449 target fish
species (Tables 4.7-1 through 4.7-3).
Stomach contents were collected from the first eight fish per target species and age class that
were captured at each sampling site during the sampling period (Tables 4.7-1 through 4.7-3).
Fish were anesthetized with Aqui-S 20-E, measured for fork length (mm), weighed (g), and their
stomach contents were flushed with a 10-mL (0.3 oz) syringe assembly (Meehan and Miller
1978). Stomach contents were flushed into a Whirl-Pak bag and preserved in at least 70-percent
ethanol. Scale samples and tissue samples for stable isotope analysis were taken from the fish at
this time as well, using methods detailed in Section 4.6.
Stomach content samples were examined under a dissecting microscope in the laboratory at
UAF. Invertebrate prey items were identified to life stage (i.e., larva, pupa, nymph, or adult) and
family when possible, or otherwise to the lowest possible taxonomic level. Invertebrates were
categorized as aquatic or terrestrial based on their taxon and life stage (Merritt et al. 2008). Fish
prey items were identified to species when possible, or otherwise to the lowest possible
taxonomic level. The body lengths of intact prey organisms were measured to the nearest
millimeter, and the lengths of partially digested prey were estimated based on intact individuals
of the same taxon that appeared similar in size. The dry mass of prey organisms was determined
from length-weight regression relationships (ISR Part A, Section 4.9.1.2.; AEA 2014a). All
stomach contents were archived in 95-percent ethanol for future verification.
Diet composition data were summarized in terms of diet proportions by dry mass, the most
relevant metric for energy flow and food web studies (Chipps and Garvey 2007) and were
calculated for each fish and summarized under five broad categories: aquatic life-stages of
freshwater-derived prey (such as chironomid larvae and pupae), terrestrial life-stages of
freshwater-derived prey (such as adult chironomid midges), terrestrial invertebrates (such as ants
and caterpillars), fish and non-salmonid fish eggs, and salmon eggs. The wet mass of fresh
salmon eggs was estimated from a length-weight relationship from the literature (Fleming and
Ng 1987). The wet mass of prey fish was estimated based on taxon-specific length-mass
relationships calculated from fish measured and weighed by the Fish Distribution and
Abundance in the Middle and Lower Susitna River Study (Study 9.6.). The dry mass of fish and
fish eggs were estimated from wet masses using percent dry mass values of 24.9 percent for
Oncorhynchus spp., 22.5 percent for sculpins, and 40 percent for fresh salmon eggs (Ashton et
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al. 1993, Brey et al. 2010). The resulting dry mass values estimated for fish and fish eggs were
similar to dry mass values measured directly for similarly sized salmon fry, sculpins, and salmon
eggs in other Alaskan rivers (M. Wipfli, unpublished data).
Diet composition data from each species and size class were analyzed using MANCOVA
(multivariate analysis of covariance) to identify spatial, temporal, and ontogenetic patterns. Diet
proportions were arcsine-square root transformed to meet the assumption of normality (Chipps
and Garvey 2007). The transformed diet proportions of five prey categories were specified as
response variables in separate MANCOVA models for each species and size class. Each model
tested for fixed effects of season, focus area, and habitat type, with fork length as a covariate.
Statistical models for Chinook Salmon and Coho Salmon also tested for an effect of year. Year
was not included in models for Arctic Grayling, which were only sampled in 2014, or large
Rainbow Trout, due to a small sample size in 2013. Small Rainbow Trout diet data were
examined graphically, but not tested statistically due to the small sample size. Statistical results
were evaluated using a significance level (alpha) of 0.05.
In addition, at the ISR meeting held in October 2014, a request was made to determine whether
the 2013 fish diet dataset was sufficient to quantify fish diet composition. In December 2014,
AEA filed a technical memorandum, Fish Diet Sample Size Sufficiency Analysis, which describes
an analysis of the 2013 stomach content data using cumulative prey curves to determine whether
this dataset was sufficient to quantify fish diet composition (UAF and R2 2014).
Additionally, 2013 lab analysis was completed post-ISR filing in June 2014, and results were
presented in 2013 Initial River Productivity Results Technical Memorandum (R2 and UAF
2014b) in September 2014.
4.7.1. Variances
The methods for collecting fish diet information were conducted as in 2013, as described in the
ISR Part A, Section 4.9 (AEA 2014a) with variances which included: 1) elimination of field
determinations of fish stomach emptiness to reduce uncertainties in sample collection (ISR Part
A, Section 4.9.1.1.; AEA 2014a); and 2) estimating dry weights for prey items in stomach
contents using length-weight relationship data (ISR Part A, Section 4.9.1.2.; AEA 2014a). In
addition, the modification proposed in the ISR Part C, Section 7.1.2.5. (AEA 2014a) to include
Arctic Grayling juveniles and adults as target species/lifestages, was conducted as part of the
2014 field collection efforts for the Fish Diet Analysis objective.
4.8. Characterize Organic Matter Resources (e.g., available for
macroinvertebrate consumers) Including Coarse Particulate
Organic Matter, Fine Particulate Organic Matter, and
Suspended Organic Matter in the Middle and Lower Susitna
River
AEA implemented the field methods as described in the Study Plan (River Productivity IP
Section 2.4, R2 2013a; FERC 2013) with no variances. All lab processing and analysis was
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conducted as described in the ISR (Part A, Section 4.10; AEA 2014a), with the exception of the
variance explained below (Section 4.8.1).
In 2013, a total of 271 Hess samples, 70 petite Ponar grab samples, and 92 drift samples were
collected from the 20 study sites and submitted to the taxonomy laboratory, which also processed
them for organic matter (OM) content (Table 4.8-1). The 2013 lab analysis for OM was
completed in June 2014. In 2014, only drift samples were collected, resulting in a total of 108
drift samples from 20 study sites submitted to the taxonomy laboratory (Table 4.4-2) which also
processed them for OM content. Processed sample results were used to calculate estimates of
total ash free dry mass (AFDM) weights per unit area for organic matter for each site for each
sampling event period, for both benthic organic matter (grams per square meter [g/m2]) and drift
(or seston) organic matter (mg/ft3). Results for both years are presented in Section 5.6 of this
report.
4.8.1. Variances
The methods for collecting organic matter information were conducted, as described in the ISR
Part A, Section 4.10 (AEA 2014a) with one variance: 1) For the first sampling event (Spring
2013), the laboratory did not separate benthic OM retained from Hess and petite Ponar
subsamples into separate CPOM and fine particulate organic matter (FPOM) fractions, giving
only a total OM result; this was limited to only this sampling event for only benthic Hess and
Ponar samples.
4.9. Estimate Benthic Macroinvertebrate Colonization Rates in the
Middle Susitna River Segment under Pre-Project Baseline
Conditions to Assist in Evaluating Future Post-Project Changes
to Productivity in the Middle Susitna River
Lab analysis of 2013 field data was completed post-filing ISR in June 2014, and results were
presented in 2013 Initial River Productivity Results Technical Memorandum (R2 and UAF
2014b) in September 2014.
4.10. Variance: Characterize the Pre-Project Benthic
Macroinvertebrate Communities, with Regard to Species
Composition and Abundance, and Algal Production in Selected
Susitna River Tributaries and Lake Systems Located above
Devils Canyon
This objective was listed in the ISR Part C, Section 7.1.2.7 (AEA 2014a) as a proposed
modification, and was conducted in the field in 2014 as part of the River Productivity Study.
Because a Study Plan Determination regarding the proposed modifications details in the ISR was
delayed, this entire objective is a variance to the approved Study Plan.
AEA collected benthic macroinvertebrate and algal samples once during July 2014 in riffle
habitats within nine selected tributaries located above Devils Canyon in the Middle and Upper
Susitna River basin (Figure 3-3), based on Barrick et al. (1983; APA Doc. 522), in order to
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characterize the productivity of these habitats within these tributaries under their current,
baseline condition. Invertebrate drift sampling was conducted concurrently with benthic
macroinvertebrate sampling to allow for comparisons between the drift component and the
benthic macroinvertebrate assemblage, as well as revealing the availability of terrestrial
invertebrates for fish predation. Sampling in tributaries included the collection of Hess, drift,
and algal samples, and water quality measurements within riffle habitats at one representative
site. In addition, three lakes (Tyone Lake, Susitna Lake, and Lake Louise) were sampled once
during July 2014 to characterize the productivity of these habitats under the current, baseline
condition (Figure 3-4). Due the large size of these lakes, three sites were established in each
lake, with the collection of Ponar grabs, D-net sweeps (in the littoral shoreline areas), vertical
plankton tows, and water quality measurements at each site.
This collection of benthic macroinvertebrates and algae data, along with associated water quality
data, was intended to provide a snapshot of the pre-Project condition of habitats in selected
tributary and lake systems and the levels of productivity available to support fish populations. A
majority of these systems will not be directly affected by the Project; however, passage barriers
on some tributaries would be inundated by the reservoir and thus, would provide fish access to
currently inaccessible portions of those tributaries. The information gathered in this one-time
summer sampling event will provide a basis for understanding the habitats in the middle and
upper basins that will be available to support fish after the Project is in operation.
4.10.1. Benthic Macroinvertebrate Sampling
AEA implemented the methods as described in the Study Plan (River Productivity IP Section
2.2.). A summary of 2014 activities is provided below.
Benthic macroinvertebrate sampling was conducted in fast-water mesohabitats (typically
riffles/runs) within main channel macrohabitats (i.e., main channel, split-main channel).
Sampling was conducted using a modified Hess sampler (0.93 ft2-area) with a 243-micrometer
(m) mesh net (Figure 4.6-1) (Canton and Chadwick 1984; Klemm et al. 1990). Replicate
samples (n=5) were collected at each site to allow for statistical testing of results (see Appendix
B for imagery of all sampling locations). A total of 45 Hess samples were collected from the
nine study sites in 2014 (Table 4.10-1). Measurements of depth, mean water column velocity,
and substrate composition were taken concurrently with benthic macroinvertebrate sampling at
the sample location.
Within the three lakes, a petite Ponar grab sampler (1 ft2-area) was used to sample the benthic
macroinvertebrate community from the lake bottom substrates. Similar to Hess sample
collections, replicate Ponar samples (n=5) were collected to allow for statistical testing of results.
A total of 45 Ponar grab samples were collected from the nine lake sites in July 2014 (Table
4.10-2). In addition, qualitative D-net sweep sampling was conducted along the most proximal
shoreline at each of the nine stations, collecting benthic macroinvertebrates within littoral
shoreline areas. Efforts were limited to moving the D-net (243-m mesh) rigorously through
emergent vegetation and shoreline substrates areas disturbed by kicking for a period of
approximately 10-15 minutes. Contents of the net were composited into one sample per site,
yielding nine composite D-net sweep samples.
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Benthic macroinvertebrate samples were stored in individual containers and immediately
preserved in the field with 95-percent ethanol (non-denatured). Samples were shipped to and
processed by Ecoanalysts, Inc. (Moscow, Idaho) using sample processing protocols established
by the United States Environmental Protection Agency (USEPA) for the Rapid Bioassessment
Protocols (Barbour et al. 1999) and modified for use in Alaska (Major and Barbour 2001).
Organic matter (OM) content was retained in the benthic samples and analyzed by size (coarse
and fine particulate OM) as discussed in Section 4.10.4. Data received for benthic
macroinvertebrate samples was prepared and analyzed as detailed in Section 4.3.
4.10.2. Benthic Algae Sampling
AEA implemented the methods as described in the Study Plan (River Productivity IP Section
2.3.). To allow for correlation between collections, benthic algae was collected concurrently
with benthic macroinvertebrate Hess sampling at all nine tributary sites. Rock surfaces were
sampled, based on the methods utilized by the USGS for the NAWQA program (Moulton et al.
2002), the USEPA for the Rapid Bioassessment Protocol (Barbour et al. 1999), and the USEPA
for the Environmental Monitoring and Assessment Program (EMAP; Lazorchak et al. 2000;
Peck et al. 2006). For the purposes of this study, a PVC pipe area delimiter (1.65 in. diameter)
with a neoprene collar at one end was adopted, as recommended by the USEPA methods
(Barbour et al. 1999; Lazorchak et al. 2000; Peck et al. 2006).
For each composite algal sample, five rock substrates were randomly collected around the
location associated with a Hess sample. Rock substrates were evenly collected at depths of up to
2 feet. At each location where a cobble or rock substrate was collected, measurements of depth
and mean water column velocity composition were taken. Light availability was measured at
each site location with an underwater light sensor to measure the photosynthetically-active
radiation (PAR) available to the algal community. PAR readings were taken from just below the
water surface to the stream bottom at regular 10-cm intervals. A turbidity measurement, using a
portable turbidity meter, was also taken at the sampling site to determine water clarity at the time
of collections.
For each rock, the area delimiter was placed on its upper surface, and the enclosed area on the
substrate was scrubbed with a small brush to remove any algal growth. The removed algal
material from the enclosed area and brush were then rinsed into a darkened sample container.
The five discrete collections taken from five cobbles were combined to make a composited
sample, which was placed on ice inside a cooler and kept in the dark until the sample was
processed. Five composited samples (one for each Hess sample) were collected at each tributary
site, for a total of 45 composited algae samples (Table 4.10-1).
Procedures for processing algal samples were taken directly from the Quantitative Microalgae
processing procedures (Moulton et al. 2002). An algae filtration apparatus was used to draw
subsamples of the composite sample through a 1.85-inch diameter (47-mm) glass fiber filter.
Two subsamples were taken from each composite sample to determine chlorophyll-a and AFDM
in the laboratory. The subsample filters were folded, wrapped in tinfoil, labeled, and stored in a
freezer at -4° F until shipped overnight on dry ice to the processing laboratory in Kirkland,
Washington. Benthic algae samples were processed in a laboratory, using Standard Methods
(Eaton et al. 1998; SM 10200H, SM 2540G).
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Results generated from the tributary collections include estimates of AFDM and chlorophyll-a,
with the mean and variability (95 percent confidence intervals) calculated for each site and
sampling event. Algal sampling for lake sites was conducted as part of the water quality
sampling in the water column, as discussed in Section 4.10.5 below.
4.10.3. Drift and Plankton Tows
AEA implemented the methods as described in the Study Plan (River Productivity IP Section
2.1.). Invertebrate drift sampling was conducted concurrently with benthic macroinvertebrate
sampling at all sites within the five established sampling stations to allow for comparisons
between the drift component and the benthic macroinvertebrate community, as well as reveal the
availability of terrestrial invertebrates for fish predation.
Invertebrate drift sampling was conducted in fast-water habitats, within all established sites
(Table 4.10-1), based on the USEPA’s EMAP drift net sampling protocols (Klemm et al. 2000).
A set of two drift nets with a 250-µm mesh size were used to collect duplicate samples to allow
for statistical testing of results (Klemm et al. 1990; Klemm et al. 2000). Drift sampling was
conducted at the top of a site reach during daylight hours, preferably beginning shortly after
arrival at a site. Water velocity was recorded with an in-net flow meter (General Oceanics)
along with the start and stop times marking the amount of time the nets were actively sampling.
In addition, current velocity was measured with a Pygmy current meter at the entrance of the net
and at 60 percent of the depth at the start and ends of sampling. Measurements of depth,
turbidity, and temperature were also taken with drift samples. A total of 18 drift samples were
taken from the nine tributaries during the July 2014 trip (Table 4.10-1).
Within the lake sites, a plankton tow net (80-µm mesh net with an 18-inch opening for deep
waters, or a 12-inch opening for shallow waters) was used at each of the lake sites, taking five
replicate full-depth vertical tows. A calibrated tow line (in feet) was attached to the tow net and
lowered to within 10 feet of the lake bottom (consulting the boat’s depth finder), and then slowly
pulled to the surface. The receiving bucket was carefully removed, and its contents were washed
into an 80-µm mesh screen, rinsed, transferred to a sample bottle. A total of 45 plankton tows
were collected from the nine lake sites (Table 4.10-2).
Invertebrate drift and plankton tow samples were stored in individual containers and immediately
preserved in the field with 95-percent ethanol (non-denatured). Samples were shipped to and
processed by Ecoanalysts, Inc. (Moscow, Idaho) using methods similar to those used for benthic
samples (Barbour et al. 1999; Major and Barbour 2001). For plankton tows, the laboratory
protocol included measuring and recording lengths (mm) of individual zooplankton, with an
average length calculated for later use in determining biomass estimates. Organic matter (OM)
content was retained in the drift samples and analyzed by size (coarse and fine particulate OM)
as discussed in Section 4.10.4. Data received for benthic macroinvertebrate samples was
prepared as detailed in Section 4.3. Drift density was measured by volume, per cubic foot, and
all metrics dependent upon density estimates reflect this as well. For plankton tows, density and
biomass were calculated by area, per square meter. Zooplankton biomass was determined using
the length-weight regressions from Koenings et al. (1987) and Rosen (1981), and was calculated
by area, per square meter. Community composition measures were adapted to the most common
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zooplankton taxa groups identified in the samples, and were determined by both density and
biomass.
4.10.4. Organic Matter
In order to quantify the organic matter available in the sampled tributaries for river productivity,
CPOM and FPOM (specifically fine benthic organic matter (FBOM)) were collected directly
from all benthic macroinvertebrate sampling, in Hess and Petite Ponar samples and drift net
samples. Therefore, 45 Hess samples, 45 Ponar grabs, and 18 drift samples were processed for
organic matter content (Tables 4.10-1, 4.10-2). AEA implemented the methods as described in
the Study Plan (River Productivity IP Section 2.4.).
To streamline the collection efforts, Hess sampling devices, and sieves used to rinse and retain
sample contents from Hess and grab samplers possessed a net mesh size of 250 µm in order to
retain CPOM particles and FBOM in the 250–1,000 µm size range for analysis. All organic
debris collected within each Hess and grab sample was retained with the sample and preserved in
95-percent ethanol. Suspended FPOM (seston) was collected from material in invertebrate drift
samples, using drift nets with a 250-µm mesh size in order to retain CPOM particles as well as
FBOM in the 250–1,000 µm size range for analysis. All organic debris collected within each
drift sample was retained with the sample and preserved with 95-percent ethanol.
Processing of benthic macroinvertebrates involved subsampling to acquire a 300-organism fixed-
count (±20 percent) subsample. All invertebrates were removed from debris with the aid of a
dissecting microscope (7-45x), and sorted debris was retained in a labeled bottle and stored for
later for quality assurance/quality control (QA/QC) assessment and organic matter analysis.
Organic matter retained from subsampling after organism sorting and processing was separated
from inorganic material, rinsed through 1-mm and 250-µm nested sieves, to separate CPOM and
FPOM components of the detritus, oven-dried (60°C [140°F]), and weighed. Dried components
were combusted and reweighed to determine AFDM weights (g) per subsample amount.
Weights were converted to total grams per sample, and per unit area (m2) according to the
subsample proportion, and area or volume sampled by the corresponding device.
4.10.5. Water Quality
Water quality sampling at tributary and lakes sites were collected both in-situ with a multi-
parameter water quality sonde, and by collecting water samples (grabs) to send to an analytical
laboratory for testing. Collection procedures closely followed the guidelines set forth in the
Quality Assurance Project Plan (QAPP) for Baseline Water Quality Monitoring Sampling and
Analysis Activities for the Susitna-Watana Hydroelectric Project Water Quality Study (URS and
Tetra Tech 2013). Measurements in tributaries were taken either in the late morning (10:30-
11:30), or mid-afternoon (15:00-16:00), whereas measurements in lakes were taken throughout
the day, so some results may vary accordingly.
4.10.5.1. In-Situ Water Quality Monitoring
At each site, in situ measurements of dissolved oxygen, pH, general and specific conductance,
oxidation-reduction (redox) potential (ORP), PAR, turbidity, and water temperature were made.
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A LaMotte® 2020we Portable Turbidity Meter was used to measure turbidity, and a YSI® 556
meter was used to measure the remaining field parameters during each site visit. In stream
sampling, PAR was measured with an Apogee® MQ-200 Quantum Sensor with Handheld Meter.
In lake sampling, a LiCOR® LI-192 Underwater Quantum Sensor with a LI‑250A meter, and a
2009S Lowering Frame was used for measuring PAR (Figure 4.10-1).
Tributary sample sites were located at water depths less than 3 ft (< 1m) deep and field personnel
collected samples by positioning the water quality equipment on the nearby bank, or within the
stream on larger substrates, and extending the sonde out into the channel. The multimeter sonde
was placed on the stream bottom, but within the stream currents, to take parameter readings.
Sample vials for the turbidity testing were filled and placed within a calibrated 2020we meter.
PAR measurements were taken in depths of 2.5 to 3 feet, recorded in approximately 4 inch (10
cm) increments.
In lake sampling, the YSI sonde was attached to the Lowering frame with the LiCor Quantum
Sensor in order to collect water column profiles for in situ measurements at each site location.
The units were lowered into the water column, and measurements were collected in 3 feet depth
increments until 3 feet above the lake bottom, with a maximum depth of 96 ft (30 m).
Measurements at deep sites in Lake Louise (RP-LLO) did not reach the bottom, as those depths
exceeded the length of the probe’s cable. For LLO-1, final measurements were approximately
10 ft above the lake bottom, and for LLO-2, 37 ft above the bottom. At sites with depths of less
than 25 feet, measurements were taken in 1 foot depth increments. For PAR measurements, the
depth at which PAR is 1 percent of the ambient light level was marked as the euphotic depth;
water quality grab samples were taken at this depth, if present at a sampling site. The series of
PAR measurements were used in a regression with depth to calculate the light extinction
coefficient (Kd) and euphotic zone depth for each site, as described in Edmundson et al. (2000).
4.10.5.2. Water Quality Grab Samples
Water quality grab samples were collected at all site locations to document nutrient levels
available to algal growth and productivity. At all tributary sites and lake sites, water samples
were collected for Nitrate+Nitrite, Ammonia as N, Total Kjeldahl Nitrogen (TKN), Total
Phosphorus (TP), Soluble Reactive Phosphorous (SRP), and Dissolved Organic Carbon (DOC).
At all lake sites, additional water samples were collected for Alkalinity and Chlorophyll-a (Table
4.10-3).
Water quality grab samples were collected using a peristaltic pump and non-reactive tubing
system, following the QAPP and protocols therein. The peristaltic pump was used to pump
water at each sample site into the sample containers. Tributary sample sites were located at
water depths less than 3 ft (< 1m) deep and field personnel collected samples by positioning the
pump on the nearby bank, or within the stream on larger substrates. The sample tubing was
extended out into the stream channel into the current. Once the tubing was positioned and
secured, the pump was turned on and ran for several seconds to flush/rinse the pump/tubing
system. Samples were collected from the tubing and into the proper sample containers supplied
by the contract laboratory and labeled accordingly. Sample containers that did not contain a
preservative were rinsed three times with sample water prior to collecting the sample. Field
duplicates and field blanks were collected at the Watana Creek site (RP-WAT-1), given the
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QAPP protocol that field duplicates be taken a rate of 1 for every 10 water grab samples, and
field blanks 1 per every 20 sites.
For lake sampling, water quality grab samples were collected at up to three separate depths in the
water column at each site using a Van Dorn vertical water sampler (Figure 4.10-1). The Van
Dorn sampler was lowered down through the water column at each lake site, and a messenger
was sent down the line to close the sampler at three depths: near surface, the euphotic depth, and
2-3 feet from the lake bottom (Table 4.10-2). For sites with depths greater than 25 feet, near
surface depth was approximately 6 feet deep. For sites with depths less than 25 feet, near surface
depths were approximately 2 feet deep, and euphotic depths were not available, as higher light
levels reached the lake bottom. At one site, RP-LTY-1, depths were 4.5 feet, so only one water
quality grab sample was taken (Table 4.10-2). Field duplicates and field blanks were collected at
the last site on the final day, on Lake Louise (RP-LLO-3).
Samples were placed on ice in a cooler upon collection in the field. Non-preserved samples were
transferred to a deep freezer at the field camp site, where they were stored at -4° F until either
delivered to SGS in Anchorage at the conclusion of the week or until shipped overnight on dry
ice to the IEH-Aquatic Research in Seattle, Washington at the conclusion of the field trip, within
22 days of the first sample collection. For chlorophyll-a samples, AEA followed the methods as
described in the Study Plan (River Productivity IP Section 2.3.2.; R2 2013a). An algae filtration
apparatus was used to draw approximately 500 ml of the water sample through a 1.85-inch
diameter (47-mm) glass fiber filter. The filter was folded, wrapped in tinfoil, labeled, and stored
in a freezer at -4° F until shipped overnight on dry ice to the processing laboratory AMTEST in
Kirkland, Washington. Each batch of water quality samples had a separate completed chain of
custody (COC) sheet that documented and tracked sample possession at all times.
5. RESULTS
5.1. Characterize the Pre-Project Benthic Macroinvertebrate and
Algal Communities with Regard to Species Composition and
Abundance in the Middle and Lower Susitna River
5.1.1. Benthic Macroinvertebrate and Algal Sampling
No field work was conducted for this objective in 2014. However, the results of the 2013
benthic macroinvertebrate sampling for Hess and petite Ponar samples were reported in Section
3.1. of the 2013 Initial River Productivity Results Technical Memorandum (R2 and UAF 2014b).
The results of 2013 benthic algal sampling was reported in the ISR Part A, Section 5.2. (AEA
2014a). As presented in R2 and UAF (2014b), results from the 2013 benthic macroinvertebrate
sampling showed that tributary mouths were generally highest in mean benthic density, taxa
richness, and EPT Taxa, and often showed higher percentages of those EPT taxa in community
compositions. Side sloughs and upland sloughs displayed seasonal changes with higher densities
and taxa richness measures later in the sampling season. Main channel and side channel sites
often displayed the lowest density and taxa richness measures in comparison to other
macrohabitats, although exceptions were evident such as disconnected side channels. As
presented in the ISR Part A, Section 5.2 (AEA 2014a), results from the 2013 benthic algal
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sampling showed chlorophyll-a and AFDM estimates were lower in mainstem macrohabitats
(main and side channels) than in other macrohabitat types, especially off-channel habitats (side
sloughs, upland sloughs). Data from the next year of study will be reviewed independently to
see if these trends hold up over two years and/or if different trends are evident.
Results presented herein include lab results for emergence traps and large woody debris
sampling from 2013 efforts.
5.1.1.1. 2013 Adult Insect Emergence Trapping
Processed sample results for adult emergence traps were used to calculate an assortment of
metrics for each of the 20 sites during each collection period. For simplicity, metric results are
presented in the broader descriptive classes, with an abundance measure, taxa richness measures,
and composition measures. Values for all metrics calculated for emergence traps at the River
Productivity study sites over the course of the 2013 sampling season are presented in Tables 5.1-
1 through 5.1-10. Results for density are calculated as numbers per square meter per day, and
graphically presented in Figures 5.1-1 through 5.1-5.
In 2013, estimates of daily emergence densities were variable among reaches and sampling
periods, showing peaks of emergence largely in July and August. Many comparisons amongst
sites are precluded due to lost samples and unknown sampling durations; however, observations
can be noted. At sites above Devils Canyon, main channel habitats recorded higher daily
emergence densities than other macrohabitats, reaching nearly 250 individuals/m2/day at RP-
184-3 in the latter half of July (Figure 5.1-1), and 41.7 individuals/m2/day at RP-173-2 in early
August (Figure 5.1-2). At Middle Reach sites below Devils Canyon (FA-141 [Indian River] and
FA-104 [Whiskers Slough]), upland sloughs and tributary mouths were generally higher in daily
emergence densities compared to main channels and side channels (Figures 5.1-3 and 5.1-4). In
the Lower Reach, daily emergence densities were also higher in the upland slough site (31.6 to
42.2 individuals/m2/day) compared to those recorded for main and side channel habitats (Figure
5.1-5).
Overall emergence taxa richness during 2013 was also variable were variable among reaches and
sampling periods, again showing peaks of emergence largely in July and August. The range of
taxa richness recorded was from 2 taxa, at the side channel site RP-104-5 in July and early
August sample periods (Table 5.1-7), to 36 taxa, at the upland slough site RP-81-1 for the July
period (Table 5.1-9). The EPT taxa richness recorded from emergence trap samples was
relatively low, ranging from 0 to 7 taxa in 2013 samples. The highest EPT taxa numbers
recorded were 6 taxa at the mouth of Tsusena Creek (RP-184-1) during July, including 3
caddisfly taxa (Tables 5.1-1) and 7 taxa at the RP-81-4 side channel site during July, including 3
stonefly taxa (Table 5.1-9).
Overall adult emergence community composition measures revealed that all sites were
dominated by aquatic taxa emerging in samples, generally averaging around 80 to 95 percent of
the relative abundance, and comprised largely by chironomids, which were generally 50 percent
or higher at most sites (Tables 5.1-1 to 5.1-10). Higher relative abundances of terrestrial taxa
were often recorded in samples that were stranded out of the water upon retrieval, generally
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marked by increased relative abundances of Hemiptera (true bugs), Hymenoptera (sawflies,
wasps, bees, and ants), and Other Diptera (true flies) (Tables 5.1-1 to 5.1-10).
The contribution of EPT taxa to community compositions appeared to be influenced by
macrohabitat types. The highest relative abundances of emerging stoneflies (primarily
Chloroperlidae and Perlodidae) in trap samples were recorded at main channel and side channel
sites. In addition, the mouths of the named tributaries (Indian River, Tsusena Creek, Whiskers
Creek, and Montana Creek) tended to have greater contributions of caddisflies to the overall
community compositions than at other sites. No discernible trend was observed for mayflies, as
they varied in relative abundances in nearly all macrohabitats.
5.1.1.1.1. RP-184 (Watana Dam)
At the Watana Dam station, estimates of emergence density (individuals/m2/day) were noticeably
higher at the main channel site (RP-184-3) over the July 12-29 period, totaling 239.2
individuals/m2/day, compared to 25.9 individuals/m2/day at the mouth of Tsusena Creek (RP-
184-1) (Figure 5.1-1). In contrast, emergence densities were significantly lower in later periods.
Taxa richness results ranged from 10 to 28 taxa, with the tributary mouth showing a peak of 28
taxa over the July 12-29 period, dropping to 10 later in the August 21-September 22 period,
whereas the main channel site, RP-184-3, showed mean taxa richness ranging from 14 to 28 taxa
(Table 5.1-1). Community compositions of the adult emergents were largely aquatic taxa (50.5
to 86.8 percent), comprised mostly of chironomids, Other Diptera (Empididae and
Dolichopodidae), and stoneflies (Chloroperlidae and Perlodidae) (Figure 5.1-1, Tables 5.1-1 and
5.1-2). Terrestrial taxa represented between 13.2- and 49.5 percent, comprised of Hemiptera,
Hymenoptera, and several taxa of flies (Other Diptera).
5.1.1.1.2. RP-173 (Stephan Lake Complex)
Within the RP-173 station, emergence density estimates ranged from 3.6 individuals/m2/day at
RP-173-1 in September, to 41.7 individuals/m2/day in the main channel (RP-173-2) during the
July 29-August 19 period. Lower emergence densities were observed in the final September
period.
Taxa richness results ranged from 3 to 26 taxa. At site RP-173-1(unnamed tributary mouth) taxa
richness peaked at 21 taxa over the July 11-29 period, dropping to 3 later in the August 31-
September 23 period. The side slough site, RP-173-4, showed mean taxa richness shifting from
3 taxa in early August to 26 taxa in late August (Table 5.1-3). Community compositions of the
adult emergents were largely aquatic taxa (35.7 to 96.7 percent), generally comprised mostly of
chironomids, mayflies (largely Baetidae), and stoneflies (Chloroperlidae and Perlodidae) (Figure
5.1-2, Tables 5.1-3 and 5.1-4). Terrestrial taxa represented between 3.3 and 64.3 percent, mostly
represented by several taxa of flies (Other Diptera), as well as some Coleoptera (semi -aquatic
beetle taxa), Hemiptera and Hymenoptera.
5.1.1.1.3. RP-141 (Indian River)
Emergence density estimates were highest at RP-141-1 (mouth of Indian River), with nearly 116
individuals/m2/day recorded during the July period, and a peak of 289.8 individuals/m2/day in
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the first week of August (an 8-day period) (Figure 5.1-3, Table 5.1-5). Emergence densities at
other sites within FA-141 (Indian River) were approximately 10.2 to 53.7 individuals/m2/day in
the July and first half of August periods (Figure 5.1-3, Table 5.1-5). Trap losses or damage
prevented data collection for the later periods of the season.
Emergent taxa richnesses were similar among sites, supporting 8 to 14 taxa, with higher taxa
richness observed for the July period. The upland slough site, RP-141-4, was an exception with
a taxa richness of 21 taxa (Table 5.1-5). Community compositions of the adult emergents were
dominated by aquatic taxa (86.5 to 99.6 percent), generally comprised mostly of chironomids,
Other Diptera (Empididae during the early August peak at RP-141-1 and Dolichopodidae during
the July period at RP-141-4), and stoneflies (Chloroperlidae and Perlodidae) at the side channel
site, RP-141-2 (Figure 5.1-3, Tables 5.1-5 and 5.1-6). Terrestrial taxa represented between 0.4
and 13.5 percent, mostly represented by several taxa of flies (Other Diptera), as well as some
Coleoptera (semi-aquatic beetle taxa), Hemiptera, and Hymenoptera. As an exception, the
sample collected during the early August period at main channel site recorded 63.6 percent
terrestrial, which was nearly all Hemiptera, plus several Lepidoptera (moths and butterflies)
adults, which were classified as Undetermined, suggesting that the trap may have been stranded
for a considerable length of time during its deployment, likely washed ashore by the increased
boat traffic observed at that site.
5.1.1.1.4. RP-104 (Whiskers Slough)
At RP-104 (Whiskers Slough), emergence densities observed at most sites during 2013 did not
exceed 50 individuals/m2/day, with the exception of the upland slough site (RP-104-4) where
higher estimates ranged from 63.2 to 169.9 individuals/m2/day (Figure 5.1-4, Table 5.1-7).
Emergent density estimates were generally lower in the main channel and side channel habitat
sites, and were noticeably lower during the final collection period in September (Figure 5.1-4).
Emergent taxa richness in RP-104 generally ranged from 5 taxa to 13 taxa, with exceptions of
only 2 taxa collected in traps at the side channel site (RP-104-5), and a maximum of 21 taxa
collected at the main channel site (RP-104-2) during the latter half of August (Table 5.1-7). At
most sites, community compositions of the adult emergents were dominated by aquatic taxa
(41.2 to 100 percent), which were comprised mostly of chironomids, with some peaks in
Plecoptera (Chloroperlidae) and Trichoptera (Limnephilidae) (Figure 5.1-4, Tables 5.1-7 and
5.1-8). Terrestrial taxa generally represented between 0 and 48.5 percent, mostly represented by
several taxa of flies (Other Diptera), as well as Hymenoptera, and some Coleoptera. As an
exception, the sample collected during the late August period at main channel site (RP-104-3)
recorded 86 percent terrestrial, which was nearly all Other Diptera, again suggesting that the trap
may have been stranded for a considerable length of time during its deployment, likely washed
ashore by the increased boat traffic observed at main channel sites in the Middle Reach.
5.1.1.1.5. RP-81 (Montana Creek)
Within the Montana Creek study area, RP-81, emergence density estimates were highest within
the upland slough site (RP-81-1), with 42.2 individuals/m2/day recorded during the July period,
and a peak of 44.9 individuals/m2/day in the first half of August (Figure 5.1-5, Table 5.1-9).
Emergence densities at the main channel (RP-81-3) and side channel (RP-81-4) sites were
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approximately 1.8 to 30.6 individuals/m2/day, (Figure 5.1-5, Table 5.1-9). Trap losses or
damage prevented data collection for all but one sample at the tributary mouth site (RP-81-2).
Emergent taxa richness ranged from 3 to 36 taxa among sites. The upland slough site, RP-81-1,
recorded that higher taxa richness of 17-36 taxa, but the lowest EPT Taxa (Table 5.1-9). The
main channel (RP-81-3) and side channel (RP-81-4) sites showed more consistent EPT taxa
during July and August period collections. Community compositions of the adult emergents
were dominated by aquatic taxa (33.3 to 100 percent), generally comprised mostly of
chironomids and Other Diptera (Empididae, Dolichopodidae, and Ephydridae), along with higher
contributions of Plecoptera (Chloroperlidae and Perlodidae) at the main channel and side channel
sites (Figure 5.1-5, Tables 5.1-9 and 5.1-10). Terrestrial taxa represented between 0 and 66.7
percent of the community composition, and were largely comprised of several taxa of flies
(Other Diptera), as well as some Coleoptera (semi-aquatic beetle taxa), Hemiptera, and
Hymenoptera.
5.1.1.2. 2013 Large Woody Debris Sampling
Processed samples from LWD were used to calculate an assortment of metrics for each site for
each sampling event period. For simplicity, metric results are presented in the broader
descriptive classes, with an abundance measure, taxa richness measures, and composition
measures. Summary results (range, average, and median metric scores) for each study site are
presented in Tables 5.1-11 through 5.1-13. Mean values for all metrics calculated for the River
Productivity study sites in each seasonal event are presented in Appendix A (Tables A5.1-1
through A5.1-15.) Results for mean density, mean taxa richness, and mean EPT Taxa are
graphically presented in Figures 5.1-6 through 5.1-20.
In 2013, benthic macroinvertebrate densities on woody debris were higher overall in larger
tributary mouths and off-channel sites compared to main channel and most side channel sites.
Mouths of larger named tributaries (Indian River, Montana Creek, Tsusena Creek, Whiskers
Creek) had among the highest averaged densities (3,347 – 7,273 individuals/m2) (Tables 5.1-11
through 5.1-13). Overall densities on woody debris in Middle Reach side sloughs and upland
sloughs ranged from an average 1,433 individuals/m2 at the upland slough at RP-141-4 to 2,690
individuals/m2 at the side slough at RP-173-4 in FA-173 (Stephan Lake Complex). Side channel
macrohabitat sites recorded higher density estimates at RP-81 and RP-104 (1,222 and 2,477
individuals/m2, respectively) compared to side channels at stations farther upstream (140 – 893
individuals/m2).
Overall benthic taxa richness on woody debris during 2013 was highest in the larger tributary
mouths, ranging from 16.8 to 23.8 taxa. The EPT taxa richness was relatively low on woody
debris, ranging from average of 0.3 to 5.5 taxa. Chironomid taxa richness on woody debris
contributed 50 percent or more to the average taxa richness at all 2013 sites, and was generally
higher in tributaries, as well (Tables 5.1-11 through 5.1-13). Many of the chironomid taxa
identified were wood-boring in habit. Diversity scores were more variable, with scores ranging
from 1.06 in the main channel in the Lower Reach at RP-81-3, to 2.26 at the mouth of Whiskers
Creek (RP-104-1).
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Overall benthic community composition measures revealed the relative abundance of the three
most abundant taxa present in samples averaged around 53 to 65 percent, with higher
percentages predominantly in side channel and main channel macrohabitats (Tables 5.1-11
through 5.1-13). The contribution of EPT taxa to community compositions ranged from 0.8 to
50.3 percent, and appeared to be higher in side channel habitats, although many of these sites
also had a lower number of replicate samples representing the overall metric scores. The relative
abundance of EPT taxa was generally between 3- to 14 percent for most sites with consistently
suitable woody debris available (Tables 5.1-11 through 5.1-13). Relative abundances of
chironomids to the benthic communities were generally 50 percent or higher at most sites
(Tables 5.1-11 through 5.1-13).
5.1.1.2.1. RP-184 (Watana Dam)
At the Watana Dam station, estimates of the mean macroinvertebrate density (individuals/m2) on
woody debris were noticeably higher at the mouth of Tsusena Creek (RP-184-1), ranging from
5,726 individuals/m2 in the spring to 3,276 individuals/m2 in the fall (Figure 5.1-6). The side
channel and main channel sites (RP-184-2 and 184-3, respectively) did not offer suitable woody
debris for sampling, therefore estimates are limited to the one sample at RP-184-2, with 140.1
individuals/m2 in the summer.
Mean taxa richness on woody debris shows a similar trend, with the tributary mouth averaging
approximately 21 to 25 taxa in 2013, and the side channel site showing mean taxa richness of 6
taxa (Figure 5.1-7). Mean EPT taxa richness on woody debris ranged from 5 to 6 taxa at the
mouth of Tsusena Creek (Figure 5.1-8).
5.1.1.2.2. RP-173 (Stephan Lake Complex)
Within the RP-173 station, mean density estimates on woody debris were variable among the
sites, but generally did not exceed 2,000 individuals/m2. One exception was the side slough
macrohabitat site (RP-173-4), where densities ranged from a low of 523.5 individuals/m2 during
the spring to a high of 6,539 individuals/m2 during the summer (Figure 5.1-9). At the small
unnamed tributary mouth (RP-173-1), mean density estimated ranged from 1,387 individuals/m2
in the spring to 112.2 individuals/m2 in the fall. The main channel (RP-173-2) and side channel
(RP-173-3) sites did not offer suitable woody debris for sampling, therefore estimates are limited
to the one sample at RP-173-3, with 588.2 individuals/m2 in the summer.
Mean taxa richness measures were similar among RP-173 sites, with the tributary mouth, side
channel, and the side slough sites maintaining around 13 to 18 taxa (Figure 5.1-10). As an
exception, the tributary mouth site decreased from the spring peak of 18 taxa, to 6.67 taxa in the
summer, and low of 5 taxa in the fall (Figure 5.1-10). Mean EPT taxa richness was higher at the
tributary mouth (RP-173-1) only during the spring event, with a high of 4 taxa, compared to
other sites averaging 1 taxa or less (Figure 5.1-11).
5.1.1.2.3. RP-141 (Indian River)
Mean density estimates on woody debris were highest at RP-141 (Indian River), with over
10,000 individuals/m2 recorded in the spring and summer at the mouth of Indian River (RP-141-
1) (Figure 5.1-12). Mean densities at the side channel site (RP-141-2) were approximately 900
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individuals/m2 in the summer and fall event period. Mean density estimates at the upland slough
site (RP-141-4) gradually increased over the open water season, increasing from 486.6
individuals/m2 in the spring, to 1,488 individuals/m2 in the summer, and 1,956 individuals/m2 in
the fall (Figure 5.1-12).
Mean taxa richness measures were similar among sites, with the tributary mouth, side channel,
and the upland slough sites supporting 13 to 20 taxa (Figure 5.1-13). Mean EPT taxa richness
was higher at the Indian River mouth (RP-141-1) than other sites during the summer and fall, but
comparable to the side channel (RP-141-2) in the summer event period, with largely mayfly and
stonefly taxa (Figure 5.1-14).
5.1.1.2.4. RP-104 (Whiskers Slough)
At RP-104 (Whiskers Slough), mean densities on woody debris were highest in the mouth of
Whiskers Creek during the summer and fall months, increasing from a low of 790 individuals/m2
in the spring, to 4,458 individuals/m2 for the summer event period, and 4,767 individuals/m2 in
the fall (Figure 5.1-15). In the adjoining side slough upstream from the mouth of the creek,
mean densities gradually increased over the sampling season, from 481 individuals/m2 in the
spring, to 3,184 individuals/m2 by the fall period. Mean densities on woody debris in the upland
slough (RP-104-4) and side channel (RP-104-5) ranged from 761 to 2,622 individuals/m2 in
2013.
Mean taxa richness on woody debris was higher within RP-104 compared to other stations, with
sites exceeding 20 taxa during at least one of the seasonal events (Figure 5.1-16). Taxa richness
was generally highest during the spring for all sites except the side slough (RP-104-2), with the
upland slough recording the highest mean of 30.4 taxa. The tributary mouth site (RP-104-1)
maintained the highest mean taxa richness, ranging from 27.5 taxa in the spring to 20.2 taxa in
the fall (Figure 5.1-16). Mean taxa richness in the side slough (RP-104-2) increased from a low
of 11.7 taxa during the spring, to a high of 25.4 taxa during the fall. The upland slough and side
channel sites showed a reduced mean taxa richness in the summer and fall, with an average of 12
to 13.6 taxa (Figure 5.1-16). Mean EPT taxa richness was highest during the spring event, with
peaks of 4 to 5 taxa, and summer and fall periods with an average of 2 taxa or less (Figure 5.1-
17).
5.1.1.2.5. RP-81 (Montana Creek)
At the RP-81 (Montana Creek) station, mean density estimates for woody debris were highest at
the mouth of Montana Creek (RP-81-2), averaging over 5,000 individuals/m2 during the spring
and summer periods before dropping to 558 individuals/m2 during the fall (Figure 5.1-18). Mean
density estimates at the other three sites in the study station were less than 2,250 individuals/m2
in the spring and summer, and ranged from 64 to 391 individuals/m2 in the fall (Figure 5.1-18).
Mean taxa richness measures on woody debris in the Montana Creek study area were higher
during the spring event period, declining during the summer and fall periods. The tributary
mouth site (RP-81-2) maintained the highest mean taxa richness, ranging from 22.8 taxa in the
spring to 11.8 taxa in the fall event (Figure 5.1-19). Highest mean taxa richness in the side
slough (RP-81-1) and side channel (RP-81-5) sites in the spring were both near 20 taxa each.
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Mean EPT taxa richness was consistently higher at the side channel site (RP-81-5) than the other
three sites, with a mean ranging from 4.2 to 4.8 taxa (Figure 5.1-20).
5.2. Estimate Drift of Invertebrates in Selected Habitats within the
Middle and Lower Susitna River to Assess Food Availability to
Juvenile and Resident Fishes
A total of 108 drift net samples and 105 plankton tow samples were collected from the 25
sampling locations and submitted to the taxonomy laboratory in 2014 (Table 4.4-2). Processed
sample results were used to calculate an assortment of metrics for each site for each sampling
event period. Summary results (range, average, and median metric scores) for each study site for
a selection of metrics are presented in Tables 5.2-1 through 5.2-3. For simplicity, metric results
are presented in the broader descriptive classes as discussed in the methods section for each
study station.
Mean values for all drift net and plankton tow metrics calculated for the River Productivity study
sites are presented in Appendix A (Tables A5.2-1 through A5.2-10). Results for mean density
and taxa richness estimate for drift nets and plankton tows are graphically presented in Figures
5.2-1 through 5.2-10.
Overall estimates within the study sites in 2014 revealed higher densities per cubic foot (ft3) of
water in sites characterized as non-flowing habitats that were sampled with plankton tows
compared to flowing water habitats that were sampled with the drift nets. Upland sloughs and
side sloughs showed among the highest overall averaged densities via plankton tows (1.14 –
43.82 individuals/ft3) in the study year (Tables 5.2-1 through 5.2-3). For flowing habitats,
mouths of the tributaries (RP-184-1, RP-141-1, RP-104-1, RP-81-2) showed higher overall drift
densities as compared to nearby main channel and side channel sites.
Overall drift taxa richness during 2014 was highest in tributary mouths and main channel habitat,
followed by side channels; fewer taxa were captured in plankton tows taken in off-channel
habitats (side sloughs and upland sloughs) (Tables 5.2-1 through 5.2-3). Both the EPT taxa
richness and overall chironomid taxa richness were higher in tributaries and main channel
habitats than in the slough habitats. The higher taxa richness in tributary mouths and main
channel habitats were also reflected in higher diversity scores for these habitats; diversity often
exceeded an overall average score of 2.5 (Tables 5.2-1 through 5.2-3).
In 2014, drift community composition measures revealed the relative abundance by the three
most abundant taxa present averaged between 38 to 82 percent for most sites. The dominance of
the top three taxa averaged higher in upland and side sloughs as compared to other habitats (64
to 82 percent). Sites above Devils Canyon showed community compositions largely comprised
of chironomids, with smaller relative abundances of EPT (averages ranging from 6.3 to 17
percent in flowing water habitats, less than 1 percent in slough habitats) and zooplankton
(averages ranging from 0 to 13.3 percent, with higher averages in main and side channels) (Table
5.2-1). At sites below Devils Canyon, flowing water sites (tributary mouths, main channels, and
side channels) displayed communities mostly composed of chironomids and a sizeable
contribution of EPT (averages ranging from 8 to 24 percent), whereas slow-water habitat sites
were comprised of chironomids and a larger relative abundance of zooplankton (averages
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ranging from 2.5 to 34 percent), especially at upland slough sites (Tables 5.2-2 and 5.2-3). One
notable exception was the unusually high zooplankton relative abundance estimate at RP-104-1
(26.4 percent), at the mouth of Whiskers Creek (Table 5.2-2), possibly due to a slower backwater
area that sometimes formed upstream of the mouth.
5.2.1. RP-184 (Watana Dam)
In 2014, mean drift densities were higher at the mouth of Tsusena Creek (RP-184-1), where they
ranged from 2.24 individuals/ft3 during the spring to 0.88 individuals/ft3 in the summer (Figure
5.2-1). Mean drift densities in the side channel site peaked to 1.1 and 1.3 individuals/ft3 in the
spring and fall, respectively; main channel sites were lower, ranging from 0.12 to 0.64
individuals/ft3 in 2014. Mean taxa richness was also higher in the drift at the tributary mouth,
showing an average of 55 taxa in the spring, but dropping to 33 taxa in the summer, and to 18
taxa in the fall (Figure 5.2-2). Mean taxa richness for the summer was highest in the main
channel sites, averaging 45 taxa at RP-184-3 and 42.5 taxa in the main channel above the mouth
of Tsusena Creek (RP-184-4). EPT taxa richness followed a similar trend, with a higher average
of EPT taxa collected at the tributary mouth during the spring period (6 taxa), and averages of 7 -
8 taxa collected in the main channel sites in the summer sampling period. Community
compositions for drift at RP-184 show that samples were largely comprised of chironomids in
the spring and summer event periods. During the fall period, drift compositions at all sites
shifted to higher contributions of simuliids (Other Diptera), ranging from 25.7 percent at RP-
184-3, to 73.9 percent at the mouth of Tsusena Creek (RP-184-1). At the main and side channel
sites, contributions of zooplankton and other non-insect taxa also increased in the fall.
5.2.2. RP-173 (Stephan Lake Complex)
At RP-173, drift densities for drift net samples taken in the tributary mouth, main channel, side
channel, and upland slough sites ranged from 0.14 to 0.88 individuals/ft3 (Figure 5.2-3).
Plankton tow density measured at the side slough site and within the side channel and upland
slough sites during fall ranged from 0.793 individuals/ft3 in the summer in the side slough, to
78.3 individuals/ft3 in the upland slough site during the fall. Mean taxa richness was high in drift
net samples, with the tributary mouth site showing the highest average of 49.5 taxa in the
summer and dropping to 26.5 taxa in the fall (Figure 5.2-4). Mean taxa richness for the main
channel site averaged 42.8 overall in 2014, whereas the side channel site showed an overall
average of 20.9 taxa, with a spring average of 30 taxa, rising to 44 taxa in the summer before
dropping to an average of 8 taxa (from plankton tows) during the fall. In contrast, plankton tows
in the side slough site had an overall average of only 7.4 taxa, ranging from a low of 3.8 taxa in
the summer to 13.6 taxa during fall (Figure 5.2-4). Drift net samples also collected higher
numbers of EPT taxa than plankton tows, ranging from an average of 0.0 to 9.5 t axa, in
comparison to 0.0 to 0.4 taxa for plankton tows.
Community compositions for drift and plankton tows show that samples were largely comprised
of chironomids during the spring and summer sampling events. During the fall sampling event,
chironomid contributions were reduced. At the small unnamed tributary mouth (RP-173-1), fall
drift captured higher amounts of Baetis sp. mayflies (37.3 percent), along with simuliid larvae
and water mites. Fall drift within the main channel site (RP-173-2) shifted to increased numbers
of zooplankton (34 percent), along with simuliids and stoneflies (Taenionema sp.). Plankton
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tows collected during the fall event varied in chironomid compositions, ranging from 34.9 to
56.6 percent relative abundance; in the side channel site (RP-173-3) chironomids still dominated
with 56.6 percent of the composition, with 25.7 percent contributed to the hydrophilid beetle
Helophorus (Other Insects), and 12.7 percent zooplankton. The side slough and upland slough
sites also showed increased contributions of Helophorus, as well as the ceratopogonid Dasyhelea
sp. (Other Diptera). Drift net samples consistently collected higher proportions of EPT taxa
compared to plankton tows.
5.2.3. RP-141 (Indian River)
In 2014, drift densities were collected in the RP-141 mouth, main channel, and side channel
sites, and ranged from 0.006 individuals/ft3 at the main channel site in the spring, to 1.09
individuals/ft3at the side channel site during the summer (Figure 5.2-5). Plankton tow density
was measured at the upland slough site (RP-141-4) in the slow-water habitat, revealing densities
of 1.06 to 3.08 individuals/ft3, and additionally within the side channel site (RP-141-2) during the
fall event due to lower flow conditions, which collected 0.66 individuals/ft3. Mean drift taxa
richness was high overall, with the tributary mouth site (RP-141-1) showing an average of 48.8
taxa for the sampling seasons as well as the highest taxa richness average of 53.3 taxa during the
summer (Figure 5.2-6). As flow levels receded over the course of the sampling season, mean
taxa richness in the side channel dropped from a high of 36 taxa in summer, to 5.2 taxa in the
fall, resulting in an overall average of 15 taxa. Mean taxa richness for the main channel site (RP-
141-3) averaged around 33.2 taxa overall, ranging from 10 taxa in the spring to 21.5 taxa during
the fall event. In contrast to drift taxa richness, plankton tows resulted in generally lower taxa
richness. For example, in the upland slough site (RP-141-4), taxa richness averaged only 9.3
taxa over 2014 sampling, ranging from a low of 8.6 taxa in the fall to 9.8 taxa during the spring
(Figure 5.2-6). Drift net samples also collected higher numbers of EPT taxa (average of 1 to 10
taxa) than plankton tows (average of 0.0 to 0.4 taxa).
Community compositions for drift and plankton tows show that samples were largely comprised
of chironomids, in higher proportions during the spring and summer sampling events. Drift
samples at the mouth of Indian River (RP-141-1) had higher compositions of EPT taxa than
other sites, with an overall average of 21.5 percent. Plankton tows collected in the upland slough
had a notable contribution of zooplankton, ranging from an average of 6.7 percent in the summer
to 11.4 percent during the spring, as well as a larger contribution of Other Diptera, largely larvae
from the dipteran family Ceratopogonidae, ranging from 24.3 percent in the spring to 48.3
percent in the fall. Drift net samples consistently collected higher proportions of EPT taxa as
compared to plankton tows.
5.2.4. RP-104 (Whiskers Slough)
Mean drift density estimates for sites in the RP-104 station at Whiskers Slough in 2014 ranged
from 0.02 individuals/ft3 at the side channel site (RP-104-5) in the summer to 1.14 individuals/ft3
at the mouth of Whiskers Creek (RP-104-1) in the spring (Figure 5.2-7). Plankton tows were
utilized at the side slough and upland slough sites, and additionally within the tributary mouth
site during the summer event, due to lower flow conditions at those locations. Plankton tow
densities ranged from 1.0 to 45.9 individuals/ft3 in the upland slough (RP-104-4), from 0.39 to
4.58 individuals/ft3 in the side slough sites (RP-104-2 and -2.1), and showed density of 3.47
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individuals/ft3 in the mouth of Whiskers Creek during the summer event period (Figure 5.2-7).
Mean taxa richness was higher in the flowing water sites sampled with drift nets, with the
tributary mouth site showing a mean of 28 taxa in the spring, and 34 taxa during the fall
sampling period, the highest taxa richness recorded within the station in 2014 (Figure 5.2-8).
Mean taxa richness for the main channel site averaged around 27.7 taxa overall, whereas the side
channel site averaged 19.8 overall, ranging from 16.5 taxa in the spring to 25.5 taxa during the
fall event period. In contrast, plankton tows in the side slough sites averaged 6.2 taxa overall
during 2014, with the upland slough site averaging slightly higher, at 12.1 taxa overall (Figure
5.2-8). Drift net samples also generally collected higher numbers of EPT taxa than plankton
tows in 2014, ranging from an average of 0.5 to 6 EPT taxa, in comparison to 0.0 to 0.8 EPT taxa
for plankton tows.
Community compositions for drift and plankton tows in RP-104 reveal a wide variety of taxa
represented in the water column. Chironomids were often dominant in both drift and plankton
samples, ranging from 20.2 percent in plankton tows in the side slough just above the tributary
mouth during the spring, to 80.6 percent in drift samples taken the main channel site (RP-104-3),
also in the spring. Overall averages in the relative abundance of chironomids shows that the
main channel and side channel sites were higher in chironomid contributions that the off-channel
sites. Plankton tows collected in the slough sites also showed notable contributions of Other
Diptera, largely ceratopogonids, ranging from an average of 21.7 percent in the summer at RP-
104-1 to 67 percent during the summer at RP-104-4. Drift net samples collected higher
proportions of EPT taxa throughout the three seasons, compared to plankton tows. Zooplankton
contributions were generally higher in plankton tows; the highest relative abundance of
zooplankton was collected with plankton tows in the tributary mouth (RP-104-1) during the
summer sampling event, comprising an average 41.3 percent of the invertebrates captured at the
site. As previously indicated, the lower extent of Whiskers Creek forms a low-flow pool habitat
at certain times of the open-water season, and it is likely that this pool contributed to the higher
zooplankton presence near the mouth at the confluence with the slough.
5.2.5. RP-81 (Montana Creek)
Drift densities in 2014 were calculated for the mouth of Montana Creek, main channel, and side
channel sites and ranged from 0.005 individuals/ft3 in the side channel site (RP-81-4) during the
fall period to 0.56 individuals/ft3 at the mouth of Montana Creek (RP-81-2) in the spring (Figure
5.2-9). Drift densities were consistently higher in the tributary mouth than compared to the other
flowing water sites. Plankton tows were utilized at the upland slough site (RP-81-1) in slow-
water habitat, averaging 11.4 individuals/ft3 in summer event period, and 22 individuals/ft3 in the
spring period (Figure 5.2-9).
Mean drift taxa richness was high, with the tributary mouth site showing an overall average of
40.7 taxa, ranging from an average of 31.5 taxa in spring, to an average of 48 taxa in fall (Figure
5.2-10). Mean taxa richness for the main channel site in 2014 averaged around 43 taxa overall,
ranging from 33 taxa in spring to 52 taxa in summer. Taxa richness for the side channel site
(RP-81-4) averaged 19.3 taxa overall, whereas the side channel site established just upstream
from the tributary mouth averaged 30 taxa overall. In contrast, taxa richness in plankton tows
was lower. For example, zooplankton taxa richness in the upland slough site averaged 11.75
taxa in spring and 4.6 taxa in fall (Figure 5.2-10). Similar to overall taxa richness, average EPT
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taxa was higher in the tributary mouth, followed by the main channel. EPT taxa richness was
very low in the upland slough site, ranging from 0 to 0.4 taxa.
Community compositions for drift and plankton tows in RP-81 revealed a wide variety of taxa
represented in the water column. Drift samples often were dominated by chironomids along with
higher contributions of EPT taxa, especially in the main and side channels. Other Diptera
(generally simuliids) also were prevalent in drift samples throughout t he seasons. Plankton tows
collected in the upland slough site also showed dominant contributions of chironomids and
ceratopogonids in the spring and summer sampling periods, but during the fall sampling event,
zooplankton accounted for nearly 97 percent of the organisms collected. Zooplankton were also
present in lower relative abundances in drift net samples throughout the sampling season,
ranging from 0.4 percent to 15.1 percent.
Drift sampling results from 2013 reported similar trends as seen in 2014. Lab analysis for
several 2013 macroinvertebrate sample sets was completed post-ISR filing, and the results were
presented in the 2013 Initial River Productivity Results Technical Memorandum (R2 and UAF
2014b) in September 2014. (R2 and UAF 2014b). As presented in R2 and UAF (2014b), results
from the 2013 drift sampling effort indicated that tributary mouths generally were highest in
mean drift density, taxa richness, and EPT Taxa, and often showed higher percentages of those
EPT taxa in community compositions. Plankton tows collected within side sloughs and upland
sloughs displayed higher densities of zooplankton and non-insect taxa, as well as chironomids,
but usually showed very low taxa richness results. Main channel and side channel sites often
displayed the lowest drift density and taxa richness measures in comparison to tributary mouths
and side sloughs.
5.3. Conduct a Feasibility Study in 2013 to Evaluate the Suitability
of Using Reference Sites on the Talkeetna River to Monitor
Long-term Project-related Change in Benthic Productivity
No field work was conducted for this objective in 2014. However, 2013 lab analysis was
completed post-ISR filing in June 2014, and results were presented in 2013 Initial River
Productivity Results Technical Memorandum (R2 and UAF 2014b) in September 2014. Results
from the benthic macroinvertebrate (R2 and UAF 2014b) and algal sampling (AEA 2014a),
generally showed that Talkeetna River side sloughs and upland sloughs displayed higher
densities and the side slough showed higher taxa richness measures than were evident at the side
channel site. Comparisons to Susitna River data will be completed in the next year of study.
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5.4. Conduct a Trophic Analysis, Using Trophic Modeling and
Stable Isotope Analysis, to Describe the Food Web
Relationships in the Current Riverine Community within the
Middle and Lower Susitna River
5.4.1. Develop a Trophic Model to Estimate How Environmental Factors and
Food Availability Affect the Growth Rate Potential of Focal Fish Species
under Current and Future Conditions
Lab analysis for the 2013 data collected was completed post-ISR filing in June 2014, and results
were presented in the 2013 Initial River Productivity Results Technical Memorandum (R2 and
UAF 2014b) in September 2014. Those preliminary fish growth results were subject to change
pending completion of genetic analysis to confirm species identifications. Subsequent genetics
results provided positive species identifications for 522 of 533 Chinook Salmon and Coho
Salmon sampled during the study. The field determinations of the remaining fish were retained
or rejected based on the rates of correctly identified fish of each species in each year. In 2013,
only 40 percent of fish identified as Chinook Salmon in the field were actually Chinook Salmon
based on the genetics results. Therefore, fish identified as Chinook Salmon in 2013 were
excluded from subsequent analyses if no genetic verification was available (n = 5). In 2013, 92
percent of fish identified as Coho Salmon in the field were genetically verified as Coho Salmon.
In 2014, field determinations were 96 percent correct overall (97 percent for fish identified as
Chinook Salmon and 94 percent for fish identified as Coho Salmon in the field). Therefore, the
field determination was retained for the fish in these groups.
5.4.1.1. Fish growth rates
Length-frequency histograms from fish captured in the Fish Distribution and Abundance Study
were used to determine the modal sizes of age-0 Chinook and Coho salmon during the spring
sampling periods of 2013 and 2014, because the River Productivity Study was limited to
sampling fish ≥ 50 mm FL. These histograms indicated that the modal size of age-0 Chinook
and Coho salmon sampled in the River Productivity study area during June was 43 mm FL in
2013 and 39 mm FL in 2014 (Figure 5.4-1). These lengths corresponded to modal weights of 0.8
g in 2013 and 0.6 g in 2014, based on equation 1 (Section 4.6.1.1.).
For all other age classes and seasons, seasonal weight-at-age relationships were determined from
fish sampled and aged from scales by the River Productivity study. Age assignments of fish
collected in 2013 were re-examined after the species identifications of a subset of these fish were
reassigned based on genetics verification of the field determinations. The size-at-age
relationships presented in this report supersede the data previously presented in the 2013 Initial
River Productivity Results Technical Memorandum (R2 and UAF 2014b) in September 2014.
In 2013, forty-two Chinook Salmon, 158 Coho Salmon, and 36 Rainbow Trout were aged from
scales to determine size-at-age relationships (Figures 5.4-2 through 5.4-4). The samples of aged
fish ranged from 63-133 mm (ages 0-2) for Chinook Salmon, 48-165 mm (ages 0-2) for Coho
Salmon, and 61-301 mm (ages 0-4) for Rainbow Trout. In 2013, all Chinook Salmon sampled
during the Spring sampling event were identified as age-1 (Figure 5.4-2). Age-0, age-1, and age-
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2 Chinook Salmon were identified in the scale samples collected during the Summer 2013 event,
and only age-0 Chinook Salmon were identified in the scale samples collected during Fall 2013.
Five Chinook Salmon identified as age-2 were considered somewhat unusual, so they are
described in detail here. The age-2 Chinook Salmon were all captured at the same site, an
upland slough beaver complex near Indian River (site FDA-141-81-USB2) on August 29, 2013.
These fish all had confirmed species identifications based on genetics. These fish were larger
than all other Chinook Salmon and most Coho Salmon sampled during the study, ranging from
120-130 mm FL and 17.8-24.6 g, and their scale patterns appeared to show two annuli; however,
the scale readers could not be certain that these were not very large age 1 fish. This uncertainty
did not affect any subsequent analyses because only the growth rates of age-0 Chinook Salmon
were used as inputs to bioenergetics models (see below). In 2013, Coho Salmon scale samples
included ages 0-2 during the Spring and Fall event, and ages 0-1 during Summer (Figure 5.4-3).
Rainbow Trout ages 0-4 were identified in the scale samples collected (Figure 5.4-4).
In 2014, 163 Chinook Salmon, 137 Coho Salmon, 112 Arctic Grayling, and 18 Rainbow Trout
were aged from scales to determine size-at-age relationships (Figures 5.4-5 through 5.4-8). The
samples of aged fish ranged from 50-105 mm (ages 0-1) for Chinook Salmon, 48-134 mm (ages
0-2) for Coho Salmon, 50 to 365 mm FL (ages 0-6) for Arctic Grayling, and 50-490 mm (ages 0-
5) for Rainbow Trout. In 2014, two age classes of Chinook Salmon were identified in the scale
samples collected during the Spring sampling event (ages 0 and 1; Figure 5.4 -5). Only age-0
Chinook Salmon were represented in the scale samples collected during the Summer and Fall
2014 sampling events. In 2014, Coho Salmon scale samples included ages 0-2 during the Spring
and Fall event, and ages 0-1 during Summer (Figure 5.4-6). Arctic Grayling ages 0-6 and
Rainbow Trout ages 0-5 were identified in the scale samples collected (Figures 5.4-7 and 5.4-8).
Age-0 Chinook Salmon grew larger in 2013 than in 2014, and they also differed in size among
habitat types during 2014 (Figure 5.4-9). Chinook Salmon were 78 percent greater in mass on
average in 2013 than in 2014 (6.8 g vs. 3.8 g, respectively), and this difference was significant (p
< 0.0001). Chinook Salmon grew faster in 2013 than in 2014 (Julian date X year interaction, p <
0.01), and during the fall sampling event, Chinook Salmon were 22 percent larger in 2013 than
in 2014. However, these results were interpreted with caution because age-0 Chinook Salmon
were sampled at only three sites during summer and fall 2013, and half of these fish were
captured in a screwtrap (set at site RP-141-1, the mouth of Indian River), which could potentially
select for larger fish than other gears. Age-0 Chinook Salmon were sampled across a larger
number of sites in 2014, primarily using baited minnow traps, backpack electrofishers, and
seines. During 2014, Chinook Salmon captured in main channel and side channel habitats were
35 percent larger than those captured in off-channel habitats (side sloughs, tributary mouths, and
upland sloughs), and this difference among habitat types was significant (p < 0.001). To
incorporate this difference into the bioenergetics models, separate growth trajectory inputs were
compiled for 1) mainstem Susitna River habitats (main channels and side channels), and 2) off -
channel habitats (side sloughs, tributary mouths, and upland sloughs). Both habitat types were
modeled in 2014; however, in 2013 age-0 Chinook Salmon were only captured in off-channel
habitats in sufficient numbers to estimate growth rates.
Age-0 Coho Salmon grew slightly faster in 2013 than in 2014, but exhibited no consistent
differences in size or growth rate among habitats. Age-0 Coho Salmon were 13 percent greater
in mass on average in 2013 than in 2014 (Figure 5.4-10), and 19 percent greater during fall 2013
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than fall 2014, although there was no significant difference in body mass between years (p =
0.15). The growth rate of age-0 Coho Salmon was slightly greater in 2013 than in 2014
(marginally significant effect of Julian date, p = 0.07). The mean weight of age-0 Coho Salmon
did not differ among habitats (p = 0.65), although there was a significant interaction between
year and habitat: age-0 Coho Salmon in upland sloughs were larger on average in 2014 than in
2013 (p < 0.0001). Therefore, growth data were pooled across habitats to generate bioenergetics
model inputs for each year. Age-1 Coho Salmon grew significantly faster in 2013 than in 2014
(effect of Julian date, p < 0.0001), although they did not differ in overall body mass between
years, largely because they weighed less during spring (Figure 5.4-11; p = 0.5). Age-1 Coho
Salmon differed in weight among habitats (p < 0.01), with larger fish on average in side channels
and tributary mouths than in side sloughs or upland sloughs. Therefore, separate growth
trajectories were compiled for separate bioenergetics model inputs for 1) side channels and
tributary mouths and 2) side sloughs and upland sloughs in each year. Coho Salmon were not
captured in main channel habitats.
Ten individual passive integrated transponder (PIT) tagged Chinook Salmon and four Coho
Salmon were measured multiple times between late July and late September 2013 at River
Productivity sampling stations, providing individual growth trajectory data. These fish exhibited
growth rates averaging 1.0 percent of their body mass per day (range: -0.09 – 2.25 percent).
Based on their sizes, most of these fish were age 1. Nearly all of these marking and recapture
events occurred in side sloughs and upland sloughs in RP-104 (Whiskers Slough) and RP-141
(Indian River). At the time of report preparation, only provisional data were available on growth
rates of PIT tagged fish recaptured during the 2014 field season.
5.4.1.2. Water temperature
Daily mean water temperatures ranged from 0-17°C during the course of the study, and
substantial thermal heterogeneity was recorded on a fine spatial scale among macrohabitats
within Focus Areas. Mean temperatures were warmer overall in all habitats during 2013 than
2014, and temperatures varied considerably within years (Table 5.4-1, Figure 5.4-12). Main
channels were the warmest and side sloughs were the coldest macrohabitats on average in both
years (Table 5.4-1; Figures 5.4-13 and 5.4-14). Tributary mouths were also relatively warm, and
upland sloughs were variable, including cold habitats such as RP-104-4 and warm habitats such
as RP-81-1. Sites where the stomach contents of juvenile salmon contained salmon eggs were
also variable in temperature, ranging from cold (Whiskers side slough, RP-104-2) to warm
(Indian River tributary mouth, RP-141-1) (Figure 5.4-15). Comparisons of summary metrics
should be viewed among years, habitat types, and stations with caution because temperature
loggers were deployed for slightly different dates at each station.
5.4.1.3. Bioenergetics modeling
Overall, Chinook Salmon fed at a high rate relative to their physiological capacity, and were
often more limited by temperature than by food intake. In 2013, Age-0 Chinook Salmon grew at
a rate of nearly 3.5 percent of body weight per day during early summer in tributaries and
sloughs, and fed at a rate P = 0.91 of their theoretical Cmax under the observed conditions,
indicating that their growth rates were primarily limited by temperature rather than food.
Chinook Salmon were not captured in side channel or main channel habitats in 2013. During
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early summer 2014, Chinook Salmon in tributary mouths and sloughs grew slower than during
early summer 2013, and their feeding rate exceeded Cmax slightly, indicating temperature was the
primary factor limiting growth. Chinook Salmon were captured in side channel and main
channel habitats during 2014, and these fish fed at a similar rate and grew faster than those
captured in sloughs. Growth and consumption rates declined in late summer during both years,
with P-values falling to 0.52-0.55 (Table 5.4-2). All species and age classes grew faster, relative
to their body weight, during early summer than during late summer (Table 5.4-2).
By contrast, age-0 Coho Salmon in all habitats were predominantly food-limited during both
years, feeding at rates of P = 0.17-0.29. Age-1 Coho Salmon fed at a similar rate of P = 0.26 in
side channels and tributary mouths as well as in side sloughs and upland sloughs, indicating that
their growth rates were also primarily food-limited. These feeding rates translated into a faster
growth rate in the warmer side channels and tributary mouths (1.08 percent of body weight / day)
than in the cooler side sloughs and upland sloughs (0.61 percent of body weight / day) (Table
5.4-2). The mean weight of Age-1 Coho Salmon in sloughs decreased during late summer 2014.
However, very few age-1 Coho Salmon were captured during the fall sampling event, even
though overall catch rates were high. Thus, this result should be interpreted with caution due to
the potential influence of random variability.
The growth efficiency of juvenile salmon also varied widely, ranging from a low of -11 percent
for age-1 Coho Salmon in sloughs during late summer 2014 to a high of 31 percent for both age-
0 Chinook Salmon in mainstem habitats (main channels and side channels) and Coho Salmon in
all habitats during early summer 2013. Overall, salmon exhibited greater growth efficiency
during early summer than late summer, indicating that they met their metabolic needs with a
smaller fraction of their overall energy intake, leaving more surplus energy to allocate to growth.
The mean mass-specific growth rates (g growth/g body mass/day) of Chinook and Coho salmon
ranged from -0.17 to 3.48 percent (Table 5.4-2). This range of values was similar to the -0.09 –
2.25 percent range of growth rates measured for individual PIT tagged fish. To achieve these
growth rates, age-0 salmon consumed 8-31 percent of their body weight per day on average.
Age-1 Coho Salmon consumed 10-40 percent of their body weight per day, on average (Table
3.4-2).
5.4.1.4. Growth rate potential modeling
Growth rate potential was estimated for 49 sampling events for which all necessary field data
were available and velocities were sufficient for age-1 Coho Salmon to drift feed consistently (≥
0.29 m/s). The model predicted that age-1 Coho Salmon would achieve positive growth in 11 of
these sets of observed conditions (Table 5.4-3). The conditions supporting positive simulated
growth rates encompassed velocities ranging from 0.3-0.4 m/s, turbidity levels 0.6-46 NTU,
temperatures 3.6-10.5 degrees C, and invertebrate drift biomass density levels 0.15-5.91 mg dry
mass/m2/s (Table 5.4-3, Figure 5.4-16.) The overall range of growth rate potential values
estimated for specific sites by the model (-2.0 – 3.8 percent) was slightly broader than the
observed range of growth rates estimated from the observed seasonal weight-at-age data (-0.17 –
3.48 percent).
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5.4.2. Conduct Stable Isotope Analysis of Food Web Components to Help
Determine Energy Sources and Pathways in the Riverine Communities
5.4.2.1. 2013 Results Summary from Technical Memorandum
Lab analysis for the 2013 data collected was completed post-ISR filing in June 2014, and results
were presented in the 2013 Initial River Productivity Results Technical Memorandum (R2 and
UAF 2014b) filed in September 2014. Stable isotope mixing models from 2013 data suggest that
both spatial and an upriver-to-downriver trends exist in the relative contributions of freshwater,
terrestrial, and marine sources (R2 and UAF 2014b). An increasing proportion of marine sources
in the diets of the target fish species from June to October suggests that fish are foraging on
energy-rich spawning salmon tissue and eggs as they become available. These data corroborate
the findings from the stomach content analysis that juvenile Chinook and Coho Salmon consume
substantial amounts of marine-derived food. This is in contrast to prior juvenile salmon diet
studies in the Middle Susitna Basin, which found that these species relied almost exclusively on
aquatic and terrestrial insects (ADF&G 1983; Hansen and Richards 1985). An upriver-
downriver spatial trend was evident in the proportion of marine subsidies consumed, where
rearing salmon and resident trout are more heavily influenced by this diet source higher up in the
system. The opposite trend was expected; however, more spawning salmon were observed in
RP-104 (Whiskers Slough) and RP-141 (Indian River) at the time of sampling than at RP-81
(Montana Creek). The spatial trend may therefore be explained by the overlap of suitable
spawning habitats with rearing habitats. Mixing models also suggest differences in dietary
contributions between habitat types, where foraging target species in generally clear, oxygenated
tributary mouths and side sloughs receive a greater marine subsidy compared to more turbid side
channels and less connected upland sloughs. Again, these differences may speak to the overlap
of suitable spawning and rearing habitat.
5.4.2.2. 2013 Stable isotope post-genetic analysis modifications
After the release of 2013 preliminary stable isotope results, 2013 dietary trends were again
estimated using Bayesian mixing models with definitive species identifications from genetic
analysis as well as informative priors from the stomach content dataset. The updated diet
estimates from stable isotope data overall resulted in a greater mean importance of freshwater-
derived prey for both Chinook and Coho salmon, with a corresponding decrease in the overall
importance of terrestrial prey, and mixed changes for marine-derived prey (Figures 5.4-18
through 5.4-20). These shifts are likely an artifact both of using informative priors from stomach
content data, used to weight the posterior diet estimates in models, as well as changes attributed
to species reassignments. Despite this major modification, overall seasonal trends in the mean
contributions of freshwater, marine, and terrestrial energy sources were largely similar to the
preliminary results (Figure 5.4-18). The largest estimate shift for freshwater sources in Chinook
and Coho salmon diets occurred for the spring sampling event at RP-81-1 (upland slough;
Figures 5.4-18 through 5.4-20; 61.7 percent increase for Chinook Salmon and 41.8 percent
increase for Coho Salmon). The freshwater and terrestrial invertebrate endmembers here were
isotopically similar and the model was not able to distinguish between these two sources in the
diets. Upon incorporation of prior values weighted toward freshwater sources, their proportion
in diets increased. Updated model results showed that patterns across macrohabitat types again
were comparable to preliminary results (Figure 5.4-19). The importance of marine contributions
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to Coho Salmon shifted only slightly across all macrohabitats; this was largely the case for
Chinook Salmon, with the exception of those rearing in the RP-104-2 side slough where marine
importance decreased compared to initial results (Figure 5.4-19). All field-identified Chinook
captured at the RP-104-5 side channel were genetically identified as Coho (Figure 5.4-19).
Despite reassigning many Chinook Salmon individuals to Coho Salmon, both species generally
appear to occupy similar broad-scale foraging niches within different macrohabitat groupings
(Figure 5.4-19). Patterns across River Productivity study stations were also similar to those
reported in the 2013 ISR, where marine-derived prey contributed increasing proportions for both
species from downstream to upstream reaches (Figure 5.4-20).
5.4.2.3. 2014 Stable Isotope Analysis
To characterize baseline isotopic variability, mean 13C values of benthic algae, benthic organic
matter, and seston organic matter were compared across macrohabitat types, along an upstream
to downstream gradient, and among seasons. Understanding relative 13C values (degree of 13C-
enrichment) of carbon sources across space and time is useful in describing predominant sources
of baseline isotopic variability that ultimately affect that of aquatic consumers (Finlay and
Kendall 2007).
Algae 13C values showed significant differences by macrohabitat type and reach, but not by
season. Compared across macrohabitat types, algae exhibited the most encriched 13C values at
glacial main channels (mean 13C = -24.69‰) and side channels (-24.01‰), followed by
tributary mouths (-27.84‰), upland sloughs (-30.84‰) and side sloughs (-32.01‰) (Figure 5.4-
21). Pairwise comparisons of algal 13C values pooled by reach showed that mean 13C values
were most depleted at RP-104 (-28.38‰) and most 13C-enriched at RP-184 (-24.66‰), with
intermediate mean values at RP-81 (-26.77‰) and RP-141 (-26.49‰) (p-value range: 0.004 –
0.341; Figure 5.4-22). Mean algae 13C values did not vary significantly by season (p-value
range: 0.31 – 0.57; Figure 5.4-23).
Pooled across all sites and seasons for 2014, mean organic matter 13C did not differ
significantly between benthic and drift sample types (mean 13COMB = -27.83‰, 13COMD = -
27.82‰, p = 0.807). Therefore, OM sample types were pooled for the following analyses. OM
samples showed little variation between macrohabitat types (mean 13C range: -28.7‰ to -
27.07‰), but similar to algae, sample 13C values from glacial main and side channels were
significantly higher compared to samples from tributary mouths and slough habitats (p-value
range: <0.001 to 0.021; Figure 5.4-21). Pairwise comparisons of mean OM 13C pooled by reach
showed that samples from RP-184 were significantly 13C-enriched (-27.23‰; p-value range:
<0.001 to 0.040) compared to samples from all other reaches (RP 81: -28.08‰, RP-104: -
28.08‰, RP-141: -27.70‰; Figure 5.4-22). Pooled across sites within each season, mean OM
13C was significantly enriched in summer (-28.06‰) compared to spring (-28.06‰) and fall
samples (-28.01‰) (p-values < 0.001; Figure 5.4-23).
Averaged over all sites and seasons, larval and emergent aquatic invertebrate feeding groups
(shredders, collectors, predators, and grazers) did not show any significant differences in mean
13C (p-value range: 0.265 to 0.999). Together, all aquatic invertebrate feeding groups averaged
-28.56‰ and were significantly depleted (p < 0.001) relative to mean terrestrial 13C values
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(26.34‰). Aquatic invertebrate mean 13C exhibited the same pattern by macrohabitat type as
algae, where samples from main channels (-26.95‰) and side channels (-26.76‰) were most
13C-enriched, followed by tributary mouths (-28.04‰), upland sloughs (-32.69‰), and the side
slough (-33.45‰; Figure 5.4-21). Some of these differences were significant (p-value range: <
0.001 to 0.994). Pooled by reach, aquatic invertebrates again showed the same 13C pattern as
algae, where RP-104 invertebrates were collectively most depleted (-31.19‰), RP-184
invertebrates were most 13C-enriched (-26.69‰), and those from RP-81 and RP-141 exhibited
intermediate values (-28.01 and -27.98‰, respectively), resulting in an overall insignificant trend
from downstream to upstream across reaches (p-value range: < 0.001 to 0.157; Figure 5.4-22.
Aquatic invertebrate mean 13C did not differ by season (p-value range: 0.067 to 0.830; Figure
5.4-23).
Strong correlations between 13C signatures suggested that all freshwater invertebrate feeding
groups relied primarily on freshwater, rather than terrestrial sources of carbon (Figure 5.4-24).
Site-specific mean algal 13C predicted site-specific mean primary consumer 13C better than did
terrestrial organic matter (OM) 13C for all freshwater primary consumer groups. All simple
linear regressions of collector, grazer, and shredder invertebrate 13C against algal 13C were
significant (p < 0.02) and resulted in relatively high r2 values (range: 0.48-0.80), whereas all
relationships of invertebrate groups to terrestrial OM were not significant (p > 0.05) and had very
low r2 values (range: 0.01-0.2; Figure 5.4-24). Collectors had the strongest reliance on algal
carbon sources, followed by grazers and shredders.
Contributions of freshwater, terrestrial, and marine diet sources to each target fish species were
estimated using a Bayesian stable isotope mixing model (MixSIAR; Stock and Semmens 2013)
and compared across macrohabitat types, study reaches, and seasons. Mixing model results
suggest that for juvenile Chinook and Coho salmon, freshwater and terrestrial sources
contributed substantially to consumer tissue, while marine-derived food was less important. In
general, marine sources contributed substantially to Rainbow Trout as compared to other fish
species, while freshwater prey were most important to Arctic Grayling.
Mixing model results suggested that juvenile Chinook Salmon consumed primarily freshwater
sources in 2014, while terrestrial invertebrates and salmon eggs were secondary prey items .
Across all sites and seasons, freshwater prey comprised an average of 59.6 percent ± 14.2 SD of
juvenile Chinook Salmon diets, while the overall mean contribution of terrestrial prey was 27.5
percent ± 13.4 SD (Tables 5.4-4 through 5.4-6; Figure 5.4-25); marine-derived prey were least
important in their diets across all sites and seasons (mean: 12.9 percent ± 8.2 SD) (Tables 5.4-4
through 5.4-6; Figure 5.4-25). In 2014, contributions of each prey source among habitat types
showed less contrasting seasonal trends compared to the previous year. Mixing models for
Chinook Salmon caught in main channel, side channel, and tributary mouth sites showed the
importance of freshwater prey to diets either decreasing slightly from spring to fall or with the
lowest overall contribution during the summer. Terrestrial prey showed complementary seasonal
trends for fish in the same macrohabitats, where mean contributions either increased from spring
to fall or peaked in summer. Seasonal trends of marine contributions were highly variable
among sites sampled, however in sites where spawning salmon were observed in relatively
higher densities (RP-141 tributary mouth and upland slough), the mean contribution of marine
prey sources increased slightly from summer to fall. Fish sampled in most sites showed a
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decrease in the mean contribution of marine sources from spring to summer. Macrohabitat types
sampled in 2014 also showed significant overlap in the possible mean contributions of each prey
source, with notable exceptions at previously mentioned sites where spawning salmon were
observed in relatively higher densities and a higher proportion of stomach contents contained
salmon eggs. Comparisons of diet composition by distance from the river mouth did not yield
any consistent or significant patterns (box colors, Figure 5.4-25).
Overall food resource contributions for Coho Salmon were similar to those for juvenile Chinook
Salmon, where freshwater prey were the primary food source (61.8 percent ± 12.7 SD), followed
by terrestrial (23.6 percent ± 21.6 SD) and marine-derived food sources (14.5 percent ± 8.2 SD)
(Tables 5.4-4 through 5.4-6; Figure 5.4-26). Trends for all sources were largely mixed but
consistent across seasons, with the exception of Coho Salmon at the RP-81 upland slough, where
freshwater prey noticeably declined from spring to fall, complemented by an increase in
terrestrial sources. Spatial comparisons of contributions also did not reveal any major trends.
Sources across all macrohabitats were fairly consistent in Coho Salmon diets, and there was not
any apparent trend from upriver to downriver Focus Areas.
Low sample sizes for Arctic Grayling precluded stable isotope diet analysis for most sites where
they were captured. The majority of sites where sample sizes were sufficient and mixing models
could be completed are within RP-184 (Tables 5.4-4 through 5.4-6; Figure 5.4-27). Across all
sites and seasons, freshwater food sources were slightly more important to juvenile and adult
Arctic Grayling relative to juvenile salmon (mean: 64.1 percent ± 13.9 SD), while terrestrial
source contributions were comparable (27.5 percent ± 13.3 SD) and marine-derived
contributions were significantly reduced (8.4 percent ± 6.1 SD) (Figure 5.4-27). Marine prey
was of low importance across all macrohabitats (RP-184 tributary mouth, main channel, and side
channel, and RP-141 main channel). Terrestrial contributions were slightly higher at the RP-184
tributary mouth compared to other macrohabitats, however this did not appear to be a significant
difference. When pooled across seasons, mixing models did not reveal any significant trends for
any energy source (Tables 5.4-4 through 5.4-6; Figure 5.4-28).
Mixing models for Rainbow Trout were pooled by season and size class due to low sample sizes
(Figure 5.4-28). Overall, freshwater and terrestrial sources were less important (respective
means: 51.0 percent ± 15.5 SD; 16.1 percent ± 11.4 SD) compared to juvenile Salmon and Arctic
Grayling, while marine-derived sources made up a significantly greater proportion of diets
(mean: 32.9 percent ± 14.6 SD) (Figure 5.4-28). Contributions of each source exhibited very
little change across seasons.
5.5. Characterize the Invertebrate Compositions in the Diets of
Representative Fish Species in Relationship to their Source
(benthic or drift component)
5.5.1. 2013 Results Summary from Technical Memorandum
Lab analysis for the 2013 data collected was completed post-ISR filing in June 2014, and results
were presented in the 2013 Initial River Productivity Results Technical Memorandum (R2 and
UAF 2014b) filed in September 2014. All three target fish species fed heavily on salmon eggs
and fish during the three sampling periods between June and September 2013. This pattern was
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relatively consistent across the three Focus Areas studied and in three out of four macrohabitat
types, with the exception of upland sloughs. These diet data are interpreted with caution and
focus on the broad trends in the data because of the relatively low sample sizes. Still, these
results contrast prior studies which found that juvenile Chinook Salmon and Coho Salmon
consumed primarily aquatic invertebrates during 1982, with very little consumption of salmon
eggs and no consumption of fish (ADF&G 1983; Hansen and Richards 1985). These historical
data indicate that juvenile Chinook and Coho salmon consumed salmon eggs at Indian River in
late September. However, there is no evidence that they utilized salmon eggs during other
spawning runs or at other sites within the Susitna Basin.
5.5.2. 2014 Overall Dietary Patterns
Stomach content analysis indicated that stream salmonids consumed primarily freshwater-
derived food resources overall, and the importance of terrestrial and marine-derived diet items
varied on temporal, spatial, and ontogenetic patterns. In 2013, 3,035 prey items were identified
and measured from 195 fish with non-empty stomachs. In 2014, 39,597 prey items were
identified and measured from 410 fish with non-empty stomachs. Overall, both size classes of
Arctic Grayling, juvenile Chinook Salmon, and small Rainbow Trout consumed primarily
freshwater prey (including aquatic and terrestrial adult life-stages; Figure 5.5-1). However, large
Rainbow Trout preyed more heavily on fish and fish eggs than on invertebrates overall, and
juvenile Coho and Chinook Salmon also relied heavily on salmon eggs at certain times and
places (Figure 5.5-1). Both salmon species and Rainbow Trout relied much more heavily on
salmon eggs during 2013 than during 2014 (Figure 5.5-2, Appendix A, Tables A5.5-2 through
A5.5-4). Grayling were only sampled in 2014, and no salmon eggs were identified in their
stomach contents. A graphical examination of Chinook Salmon, Coho Salmon, and Rainbow
Trout consumption of salmon eggs indicated that all three species exhibited an ontogenetic shift
to ovivory at roughly 55-85 mm FL (Figure 5.5-3). The smallest fish of each species
documented to consume salmon eggs were a 55 mm FL Chinook Salmon, a 62 mm FL Coho
Salmon, and an 84 mm FL Rainbow Trout (Figure 5.5-3).
Fish prey comprised a substantial fraction of fish stomach contents collected during some
sampling events; however, much of this piscivory appeared to be an artifact of the sampling
methods, rather than an accurate indication of diet composition. The majority of prey fish
specimens (76 percent of the numbers and 90 percent of the total mass) were collected from the
stomach contents of fish captured using passive gear types (i.e., screw traps, fyke nets, and
minnow traps) where fish had an extended opportunity to feed on smaller fish concentrated
inside the trap or net. Relatively few instances of piscivory were documented for fish captured
using active methods (i.e., angling, electrofishing, or seining). To avoid the possibility of bias
due to net feeding, prey fish collected from the stomachs of fish captured in passive gears were
excluded from the diet analysis. The smallest piscivorous fish sampled in active gears were a
50-mm FL Coho Salmon and a 104-mm FL Arctic Grayling (Figure 5.5-4).
5.5.2.1. Arctic Grayling
The diet composition of small Arctic Grayling differed significantly among seasons and habitats,
but not as a function of FL or Focus Area (MANCOVA; Table 5.5-1). During all seasons, small
Arctic Grayling consumed primarily freshwater prey (Figure 5.5-5). Terrestrial invertebrates
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comprised most of the remainder of the diet. During spring, small Arctic Grayling also consumed
very small fish (21-25 mm standard length [SL]). These prey fish were partially digested and
unidentifiable to species. Small Arctic Grayling relied most heavily on terrestrial infall
(terrestrial life-stages of freshwater invertebrates as well as terrestrial invertebrates) during
summer. Small Arctic Grayling consumed fish only at River Productivity Stations RP-184 and
RP-81 (Figure 5.5-6) in side channel habitats (Figure 5.5-7).
The diet composition of large Arctic Grayling (>120 mm FL) differed significantly among
seasons, but not as a function of FL, Focus Area, or habitat (MANCOVA; Table 5.5-1). Large
Arctic Grayling consumed primarily freshwater prey during all seasons (Figure 5.5-5). Large
Arctic Grayling relied most heavily on terrestrial infall (terrestrial life-stages of freshwater
invertebrates as well as terrestrial invertebrates) during summer. A single instance of piscivory
was observed for large Arctic Grayling, when a 23 mm SL prey fish (unidentifiable to species)
was consumed during spring in the tributary mouth at RP-184-1 (Figures 5.5-6 and 5.5-7).
5.5.2.2. Chinook Salmon
The diet composition of juvenile Chinook Salmon varied among years, seasons, Focus Areas,
and habitat types (MANCOVA; Table 5.5-1). Chinook Salmon did not exhibit an ontogenetic
shift in overall diet composition (no effect of FL), at least within the size range of fish sampled
(50-133 mm FL). Chinook Salmon consumed primarily freshwater prey during all sampling
periods, with the exception of fall 2013, when they fed heavily on salmon eggs (Figure 5.5-2).
Chinook Salmon relied most heavily on terrestrial infall (terrestrial life-stages of freshwater
invertebrates as well as terrestrial invertebrates) during summer in both years. Chinook Salmon
consumed salmon eggs only at RP-141 and RP-104, and only in tributary mouth and upland
slough habitats (Figures 5.5-8 and 5.5-9). During 2014, Chinook Salmon consumed small
numbers of prey fish in at RP-141 and RP-81 in side channel and upland slough habitats (Figures
5.5-8 and 5.5-9).
5.5.2.3. Coho Salmon
The diet composition of juvenile Coho Salmon shifted ontogenetically and differed significantly
among seasons, Focus Areas, and habitat types (MANCOVA; Table 5.5-1). In 2013, Coho
Salmon shifted from a diet of predominantly freshwater and terrestrial invertebrates in spring to
primarily salmon eggs by fall. In 2014, Coho Salmon relied more heavily on invertebrates
throughout the year, consuming no salmon eggs during summer and a reduced proportion during
fall (Figures 5.5-2). Terrestrial infall (terrestrial life-stages of freshwater invertebrates as well as
terrestrial invertebrates) was an important source of prey to Coho Salmon during all sampling
periods. Fish also comprised a relatively large proportion of Coho Salmon diets during many
sampling periods. Seven prey fish were measurable in the lab, including one 8-mm alevin and
two juvenile salmonids (29 and 33 mm SL). The remaining prey fish were unidentifiable to
family. Fish comprised a large proportion of the Coho Salmon diet at the RP-81 main channel
site (RP-81-3), and smaller proportions at the RP-141 tributary mouth site (RP-141-1) and the
RP-104 side slough site (RP-104-2) (Figures 5.5-8 and 5.5-9).
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5.5.2.4. Rainbow Trout
Small Rainbow Trout consumed an entirely invertebrate-based diet during spring 2013 at the RP-
81 tributary mouth (RP-81-2). During fall 2014, small Rainbow Trout consumed invertebrates at
the RP-141 tributary mouth (RP-141-1) and the RP-81 upland slough (RP-81-1), as well as
salmon eggs at the RP-104 tributary mouth (RP-104-1) (Figures 5.5-5 through 5.5-7). Too few
small Rainbow Trout were sampled (n = 7 non-empty stomach content samples) to conduct a
statistical analysis of their diet composition.
The diet composition of large Rainbow Trout differed significantly among seasons and Focus
Areas, but not as a function of FL or habitat (MANCOVA; Table 5.5-1). Large Rainbow Trout
fed nearly exclusively on invertebrates in spring, roughly equally on invertebrates, fish, and
salmon eggs in summer, and nearly exclusively on salmon eggs in fall (Figures 5.5-5). Large
Rainbow Trout fed most heavily on salmon eggs at the RP-141 and RP-104 tributary mouths and
most heavily on fish at the RP-81 upland slough (Figures 5.5-6 and 5.5-7).
Additional information on diet composition of all focal species is available in Appendix A
(Tables A5.5-1 through A5.5-10).
5.6. Characterize Organic Matter Resources (e.g., available for
macroinvertebrate consumers) including Coarse Particulate
Organic Matter, Fine Particulate Organic Matter, and
Suspended Organic Matter in the Middle and Lower Susitna
River
In 2013, both benthic (Hess, Ponar) and drift samples were collected and processed for OM
contents; in 2014, only drift samples were collected and processed. Results for both years are
presented here. Drift OM content in both years was collected in drift samples largely from main
channel, side channel, and tributary mouth sites; upland sloughs and side sloughs were primarily
low-flow habitats that were often clear pool areas with little or no organic material suspended in
the water column, and were sampled with plankton tows that collected no measureable OM
content. Exceptions occurred during the spring sampling events, when higher flows typically
breached side slough macrohabitats, allowing water from the mainstem to flow through.
Overall summary results (range, average, and median for AFDM weights/unit) are presented for
OM components within each study site for 2013 benthic OM (g/m2) in Table 5.6-1, 2013 drift
OM (mg/ft3) in Table 5.6-2, and 2014 drift OM(mg/ft3) in Table 5.6-3. Mean values for all OM
component weights calculated for the River Productivity study sites in each seasonal event are
presented for 2013 benthic OM in Table 5.6-4, 2013 drift OM in Table 5.6-5, and 2014 drift OM
in Table 5.6-6. Results for mean organic matter are graphically presented in Figures 5.6-1
through 5.6-17.
In 2013, mean benthic OM was higher overall in samples collected with the petite Ponar grab
sampler, in mostly off-channel sites. Upland sloughs had among the highest averaged overall
total benthic OM (78.3 – 133.2 g/m2) (Table 5.6-1). Main channels, side channels, and tributary
mouths typically had larger contributions of CPOM in samples than did off-channel macrohabitat
sites, which were dominated by FPOM material. Overall mean benthic OM also appears to
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increase moving downstream; total benthic OM averaged 7.9 g/m2 at RP-184, increasing to 14.6
g/m2 at RP-173, 37.4 g/m2 at RP-141, 38.2 g/m2 at RP-104, and 53.9 at RP-81.
Overall drift organic matter during 2013 was higher in main channel sites, with among the
highest averaged overall total drift OM (4.1 – 9.4 mg/ft3) (Table 5.6-2). Exceptions can be seen
at site RP-104-2, a side slough which showed a mean total drift OM of 11.24 mg/ft3; this was
recorded for the spring event, when main channel flows were high enough to breach the side
slough allowing for drift sampling (Tables 5.6-1 and 5.6-4). Also, drift OM contained a higher
proportion of the CPOM component in collected samples than was seen in benthic OM, with
greater or equal amount of coarse material compared to FPOM amounts.
In 2014, organic matter content collected in drift samples ranged from 0.12 mg/ft3 at RP-173-3 (a
side channel/side slough site) to 12.79 mg/ft3 at RP-141-2 (a side channel) (Table 5.6-3). Unlike
2013, differences in overall total drift OM were not evident among the macrohabitats; instead,
amounts were similar. Overall total drift OM in main channels ranged from 1.4 – 8.1 mg/ft3; for
side channels, 0.12 – 12.79 mg/ft3. In tributary mouths, the overall total drift OM estimates
ranged from 1.3 – 7.2 mg/ft3. However, macrohabitats did differ in the amounts of CPOM and
FPOM content. Both main channel and side channel sites contained a higher component of
FPOM compared to CPOM amounts, whereas tributary mouths usually contained more CPOM
than FPOM (Table 5.6-3).
5.6.1. RP-184 (Watana Dam)
At the Watana Dam station, estimates of the mean benthic OM (g/m2) remained below 10 g/m2
over the course of the sampling season in 2013, with the exception of the main channel site (RP-
184-3), which peaked at 20.7 g/m2 in the summer (Figure 5.6-1; Table 5.6-4). Summer
collections at all sites showed greater benthic OM estimates, with equal contributions of CPOM
and FPOM during the summer and more CPOM during the fall periods.
In 2013, mean drift OM estimates show a similar trend, remaining mostly at or below 4 mg/ft3 at
all sites during the open water season, with the exception of the main channel site (RP-184-3),
which peaked at 9.6 mg/ft3 in the summer, all FPOM (Figure 5.6-2; Table 5.6-5). Summer drift
samples at this site were collected at the beginning of a storm event, which could explain the
increased amount of OM.
In 2014, mean drift OM estimates peaked in the spring, exceeding 17 mg/ft3 with the exception
of one main channel site (RP-184-3), which peaked at 3.3 mg/ft3 (Figure 5.6-3; Table 5.6-6). A
majority of the drift OM was FPOM for the main and side channel sites. The tributary site (RP-
184-1) recorded greater CPOM in the spring. For the remainder of the sampling season, mean
drift OM estimates stayed below 5 mg/ft3. Mean amounts of CPOM and FPOM were relatively
equal in main and side channel sites during the fall sampling event, but greater amounts of
CPOM were evident in samples from the tributary mouth (RP-184-1) and at the main channel
site located immediately above the tributary mouth (RP-184-4) (Figure 5.6-3; Table 5.6-6).
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5.6.2. RP-173 (Stephan Lake Complex)
In 2013 within the RP-173 station, mean benthic OM estimates remained steady at sites with
constant flow (Hess samples from RP-173-2 and RP-173-4) or gradually declined at off-channel
sites (RP-173-3 and Ponar samples at RP-173-4) over the open water period. Benthic OM was
generally estimated at levels around or below 12 g/m2 (Figure 5.6-3, Table 5.6-4). Exceptions
were the small unnamed tributary site (RP-173-1), where benthic OM increased during the
summer period to a high of 24 g/m2 (Figure 5.6-3), and the side slough site (RP-173-4) sampled
in slower water areas with the Ponar grab sampler, where benthic OM was 26.3 g/m2 in the
spring. Additionally, results of pre- and post-storm event sampling in the side slough site
suggested that additional benthic OM was deposited in the macrohabitat due to the storm event,
with an increase from 9.3 g/m2 to 14 g/m2 for Hess samples, and 16.2 g/m2 to 48.8 g/m2 for the
petite Ponar grab (Table 5.6-4).
In 2013, mean drift OM estimates among RP-173 sites were highest in the main channel (RP-
173-2) with peaks of 12.7 to 14.5 mg/ft3 in the spring and summer event periods, decreasing to
0.78 mg/ft3 in the fall (Figure 5.6-4, Table 5.6-5). Mean drift OM at the unnamed tributary
mouth gradually increased from 1.8 mg/ft3 in the spring to 3.95 mg/ft3 in the fall.
In 2014, mean drift OM estimates among RP-173 sites were again highest in the main channel,
as well as in the unnamed tributary mouth (RP-173-1). At RP-173-2, mean drift OM peaked in
the spring with 4.4 mg/ft3, decreasing in the summer to 1.35 mg/ft3, and then to 0.56 mg/ft3 in the
fall (Figure 5.6-6; Table 5.6-6). Mean drift OM peaked at unnamed tributary mouth in the spring
(2.2 mg/ft3) and the fall (6.4 mg/ft3). Mean drift OM collected at the side channel site (RP-173-
3) and the upland slough site (RP-173-5) were 0.62 mg/ft3 or lower, and were not measured in
the fall, due to low flows and/or water levels (Table 5.6-6).
5.6.3. RP-141 (Indian River)
In 2013, mean benthic OM estimates at RP-141 (Indian River) were highest within the upland
slough site (RP-141-4) for both Hess and Ponar samples collected there, exceeding 50 g/m2,
except during the fall period for the Hess-sampled benthic OM, which dropped to 22.72 g/m2
(Figure 5.6-5, Table 5.6-4). For the side channel site (RP-141-2) benthic OM estimates was
highest at 41.7 g/m2 in the summer, dropping to 10.4 g/m2 during the fall, which was sampled
with a Ponar grab due to lack of flowing water at that time (Figure 5.6-5; Table 5.6-4).
In 2013, mean drift OM estimates were higher in the tributary mouth (RP-141-1) and main
channel (RP-141-3) sites, ranging from 4.9 mg/ft3 in the spring to 8.0 mg/ft3 in the fall at mouth
of Indian River, and near 6.0 mg/ft3 in the spring and summer in the main channel at RP-141-3
(Figure 5.6.-6, Table 5.6-5). Mean drift OM was higher in the side channel site (RP-141-2)
during the spring event period (4.8 mg/ft3), likely due to the increased flows coming from the
main channel, than in the summer and fall. Sometime during the summer of 2013, the side
channel was cut off from direct flow, and became more similar to a side slough. Drift OM
estimates were lower at the main channel site established upstream from the mouth of Indian
River, possibly due to the site’s location in a possible back-eddy caused by the inflow from the
tributary into the Susitna River.
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In 2014, mean drift OM estimates were higher in the side channel (RP-141-2), starting in the
spring at 8 mg/ft3 and increasing to 17.6 mg/ft3 in the summer (Figure 5.6-9; Table 5.6-6); lower
water levels in the fall prevented drift sampling, and samples were collected with plankton tows.
Drift OM at the tributary mouth averaged 1.32 mg/ft3 in 2014; the main channel site averaged
1.37 mg/ft3 (Table 5.6-3). The main channel site located just upstream from the mouth of Indian
River had an overall drift OM average of 2.14 mg/ft3, with 4.2 mg/ft3 in the spring (largely
CPOM), declining in the summer to 1.25 mg/ft3, and to 0.96 mg/ft3 during the fall sampling
event.
5.6.4. RP-104 (Whiskers Slough)
At RP-104 (Whiskers Slough) in 2013, estimates of the mean benthic OM (g/m2) generally were
higher in the spring, and decreased into the summer and fall periods. The highest benthic OM
estimate was nearly 300 g/m2 within the upland slough site (RP-104-4) during the spring event
period. Benthic OM here declined to 27.3 g/m2 in the summer, and 17.1 g/m2 by fall (Figure 5.6-
7; Table 5.6-4). Benthic OM in the side slough site (RP-104-2) collected with a Hess started at
26 g/m2 in the spring and increased to 31.3 g/m2 in the summer, appeared to be flushed out after a
late August storm event (9.1 g/m2), and then accumulated to 67.3 g/m2 by fall (Table 5.6-4).
Mean drift OM estimates in 2013 show increased levels during the spring. The main channel
(RP-104-3) and side slough (RP-104-2) sites showed the highest mean drift OM amounts at 12.6
mg/ft3 and 11.2 mg/ft3, respectively, during the spring event (Figure 5.6-8; Table 5.6-5). Once
the higher spring flows receded, the side slough no longer received higher flows, and plankton
tows were used for sampling. Drift OM estimates at the side channel site (RP-104-5) and the
tributary mouth (RP-104-1) were lower, at 5 mg/ft3 or less. Lower flows during the fall event
also precluded drift sampling in the side channel site at that time.
In 2014, mean drift OM estimates were highest during the spring at the tributary mouth and the
side channel sites, with 5.2 mg/ft3 and 7.2 mg/ft3, respectively (Figure 5.6-12; Table 5.6-6).
Flow levels during the spring sampling event were not high enough to breach the side slough
macrohabitat site (RP-104-2), so plankton tows were used throughout the 2014 sampling season
at that site. Reduced flows during the summer sampling event also prevented drift nets from
being used at the tributary mouth (RP-104-1), therefore no organic matter was collected at that
time, as well. During the fall sampling event, however, mean drift OM at the tributary mouth
had declined to 3.75 mg/ft3 (Figure 5.6-12; Table 5.6-6). At the side channel site, summer and
fall drift OM estimates were much lower (1.4 and 1.2 mg/ft3). At the main channel site, mean
drift OM estimates were fairly consistent, with an overall average over the 2014 sampling season
of 1.99 mg/ft3.
5.6.5. RP-81 (Montana Creek)
The 2013 benthic OM at Station RP-81 (Montana Creek) was notably greater at the upland
slough site (RP-81-1), with estimates ranging from a high of 162.5 g/m2 in the spring, declining
to 20.6 g/m2 in the fall (Figure 5.6-9; Table 5.6-4). Collections at the other sites showed benthic
OM estimates of 20 g/m2 or less.
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In contrast, mean drift OM estimates in 2013 were higher in the main channel (RP-81-3) and side
channel (RP-81-4 and RP-81-5) sites, especially during the spring period, ranging from 6.9
mg/ft3 to 9.5 mg/ft3 (Figure 5.6-10, Table 5.6-5). Drift OM estimates sharply declined into the
summer and fall periods to levels at or below 2 mg/ft3, with the exception of the side channel
site, RP-81-4, during the summer, which maintained a higher drift OM of 7.5 mg/ft3.
In 2014, peaks in mean drift OM were more varied than in 2013. Mean drift OM estimates were
lower, approaching 3 mg/ft3 during the spring and fall at the mouth of Montana Creek (RP-81-2),
and during the summer sampling event at the side channel site, RP-81-4 (Figure 5.6-15; Table
5.6-6). Drift OM estimates at other sites and sampling periods recorded levels at or below 2
mg/ft3.
5.6.6. RP-TKA (Talkeetna River)
In 2013 on the Talkeetna River, estimates of the mean benthic OM (g/m2) showed similar trends
to that seen on the Susitna River. Benthic OM estimates were higher in the upland slough site
(RP-TKA-2) sampled with a petite Ponar grab, reaching highs of 171.8 g/m2 in the spring, and
191 g/m2 in the fall event period (Figure 5.6-11; Table 5.6-4). Benthic OM estimates in the side
channel (RP-TKA-1) and side slough (RP-TKA-3) sites were generally below 15 g/m2, with the
exception of a fall increase at RP-TKA-3, to 42.2 g/m2.
In 2013, mean drift OM estimates show a similar trend as seen at the Susitna River stations, with
the side channel site (RP-TKA-1) showing higher mean drift amounts at all sites during the open
water season, ranging from a high of 6 mg/ft3 in the spring, 2.8 mg/ft3 during the summer event
period, and 4.1 mg/ft3 in the fall (Figure 5.6-12; Table 5.6-5). Drift samples in the side slough
were much lower, ranging from 0.13 mg/ft3 in the spring to 3.8 mg/ft3 during the fall event
period, suggesting there was an increase in flow in the side slough during that time.
5.7. Estimate Benthic Macroinvertebrate Colonization Rates in the
Middle Susitna River Segment under Pre-Project Baseline
Conditions to Assist in Evaluating Future Post-Project Changes
to Productivity in the Middle Susitna River
No field work was conducted for this objective in 2014. However, lab analysis for the 2013 data
collected was completed post-ISR filing in June 2014, and results were presented in the 2013
Initial River Productivity Results Technical Memorandum (R2 and UAF 2014b) filed in
September 2014. In summary, colonization in the Middle Susitna River appeared to be reached
at approximately six weeks, based upon density estimates in samples that were not disturbed or
dewatered. Factoring in taxa richness measures, the clear sites indicated that mean taxa numbers
were reached as early as four weeks. However, this could be the initial colonizing pioneer taxa,
and additional time may be necessary until the community can be determined to be in
equilibrium. For turbid conditions, the limited results suggest that a 6-8 week period may be
sufficient for macroinvertebrate colonization.
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5.8. Characterize the Pre-Project Benthic Macroinvertebrate
Communities, with Regard to Species Composition and
Abundance, and Algal Production in Selected Susitna River
Tributaries and Lake Systems Located above Devils Canyon
Laboratory processed sample results were used to calculate an assortment of metrics for each
site. For simplicity, results were presented in separate sections for tributaries and lakes, and are
organized by sampling type (benthic or water column). Results for selected metrics for each
tributary and lake site are presented herein, using the broader descriptive classes as discussed in
Section 4.3. Mean values for all metrics calculated for the tributary and lake study sites, as well
as all water quality measurements, are presented in Tables 5.8-1 through 5.8-12. Results for
calculated metrics are graphically presented in Figures 5.8-1 through 5.8-27.
5.8.1. Tributaries
5.8.1.1. Benthic sampling
Hess samples collected in July 2014 from the nine selected tributaries in the Middle and Upper
River segments of the Susitna River revealed a wide range of results describing the benthic
communities residing in each stream. Mean density estimates among the nine tributaries ranged
from a low of 1,360 individuals/m2 at the Oshetna River site to over 132,000 individuals/m2 at
the Deadman Creek site (Figure 5.8-1; Table 5.8-1). Five of the nine tributaries revealed mean
densities near or below 10,000 individuals/m2, and an additional three sites (Watana Creek, Jay
Creek and Tyone River) had mean density estimates between 20,000 and 30,000 individuals/m2.
Mean taxa richness at the nine tributary sites ranged from 22 taxa at Oshetna River to 37.8 taxa
at Tyone River (Figure 5.8-2; Table 5.8-1). All sites except Oshetna River and Deadman Creek
had an average of at least 30 taxa. For total taxa richness, a tally of the composited samples at a
site, Tyone River displayed 64 taxa, followed Fog Creek with 63 taxa, and Butte Creek with 61
taxa. Deadman Creek had the lowest total taxa richness, with 39 taxa. Mean EPT taxa richness
estimates ranged from an average of 3.2 taxa at Deadman Creek to an average of 10.4 taxa at Fog
Creek (Figure 5.8-3; Table 5.8-1). Total EPT taxa richness tallies were similar to mean EPT taxa
results, with 7 total EPT taxa at Deadman Creek and 18 total EPT taxa at Fog Creek, followed
closely by Devil and Butte creeks at 16 taxa (Figure 5.8-3). Taxa richness was dominated by
chironomid taxa at all tributaries, ranging from an average of 10.6 taxa at Oshetna River, to 19.8
taxa at Tyone River (Table 5.8-1).
Consistent with taxa richness, the community composition of most sites was primarily composed
of chironomids (Figure 5.8-4; Table 5.8-1). Mean relative abundances for chironomids ranged
from 45.4 percent at Oshetna River to 84.5 percent at Deadman Creek. The Oshetna site showed
the highest mean relative abundances for both mayflies (35.9 percent) and stoneflies (11.4
percent). The Oshetna site mayflies were largely composed of Baetis bicaudatus, Drunella
doddsii, and a number of Heptageniidae taxa. Stoneflies were mostly of the chloroperlid
Suwallia sp., with a small number of Capniidae taxa, and the Nemouridae taxa Zapada. In
contrast, while the Tyone River site had a similar mean relative abundance of chironomids (49.3
percent), it also had the highest mean contributions of caddisflies (4.1 percent, mostly
Hydroptilidae), Other Diptera (16 percent, mostly simuliids), and Non-insects (28.9 percent, a
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combination of nematodes, water mites, oligochaete worms, and snails and fingernail clams)
(Figure 5.8-4; Table 5.8-1).
For the nine tributary sites, the relative abundances of functional feeding groups showed a
dominance of collector-gatherers, ranging from 38.2 percent at Tyone River, to 84.6 percent at
Butte Creek (Figure 5.8-5; Table 5.8-1). The mean contributor of collector-filterers was highest
at Deadman Creek and Tyone River, in part due to the increased numbers of filter-feeding
simuliid larvae and several filter-feeding chironomid taxa present at those two sites, both of are
also located downstream from the outlet of a large lake. The Oshetna site had the highest scraper
percentage, with an average of 21.2 percent, due to the presence of several mayflies with that
feeding strategy (Figure 5.8-5; Table 5.8-1).
Mean benthic organic matter estimated from the Hess samples from the tributary sites ranged
from 3.5 g/m2 at Butte Creek, to 36 g/m2 at Fog Creek (Figure 5.8-6; Table 5.8-2). Three of the
nine sites, Fog Creek, Deadman Creek, and Jay Creek, had mean benthic OM amounts in excess
of 20 g/m2. At all tributary sites, CPOM exceeded or was approximately equal to the FPOM
component (Figure 5.8-6; Table 5.8-2).
Estimates of mean chlorophyll-a collected from the surface of stones at the nine tributaries
ranged from 0.14 mg/m2 at Oshetna River, to 14.82 mg/m2 at Deadman Creek (Figure 5.8-7;
Table 5.8-3). The Tyone River site had the second highest mean chlorophyll-a, at 9.34 mg/m2.
Most sites had chlorophyll-a levels between 1 and 4 mg/m2. Estimates of mean AFDM levels
ranged from 0.1 g/m2 at Oshetna River, to 27.7 g/m2 at Deadman Creek, followed by 8.8 g/m2 at
Tyone River (Figure 5.8-8; Table 5.8-3). It is interesting to note that the mean AFDM amount at
Deadman Creek was nearly equal to the mean benthic organic matter estimate for the site, as
well. The substrate sampled at Deadman Creek displayed abundant algal growth on rocks
sampled for both macroinvertebrates and algae. It may be possible that the bulk of organic
matter in Deadman Creek is from the algal source.
5.8.1.2. Drift sampling
Drift samples collected in July 2014 from the nine selected tributaries revealed higher drift
densities at sites established below lake outlets. Mean drift density was 1.12 individuals/ft3 at
Deadman Creek downstream of Deadman Lake, and nearly twice that, at 1.99 individuals/ft3, at
Tyone River downstream of Tyone Lake (Figure 5.8-9; Table 5.8-4). Lower mean drift
densities, between 0.5 and 1.0 individuals/ft3, were recorded at Fog, Watana, and Jay creeks, and
below 0.5 individuals/ft3 at Devil, Kosina, and Butte creeks, and the Oshetna River site.
Mean drift taxa richness at the nine tributary sites ranged from 14.5 taxa at Tyone River, to 49
taxa at Kosina Creek, with all sites except Tyone River exceeding a mean taxa richness of at
least 30 taxa (Figure 5.8-10; Table 5.8-4). For the total number of taxa found in drift, Jay Creek
was highest with 63 total taxa, followed by Kosina Creek with 60 taxa, and Fog and Watana
creeks with 58 taxa. Tyone River again had the lowest number of taxa, with 24 total taxa
captured in drift samples. Mean drift EPT taxa richness in the selected tributaries ranged from
one taxa at Tyone River, to an average of 10.5 taxa at Kosina Creek (Figure 5.8-11; Table 5.8-4).
Total EPT taxa in drift samples were similar to mean EPT taxa results, with only the one taxa at
Tyone River, at a total of 14 EPT taxa captured at Kosina Creek. As was seen in benthic
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samples, much of the taxa richness in drift was attributed to chironomids, ranging from an
average of 4 chironomid taxa at Tyone River, to an average of 27.5 at Kosina Creek (Table 5.8-
4). At most sites, chironomids account for at least half of the taxa richness in drift, with the
exception of Tyone River, where chironomids accounted for 29 percent of the taxa.
Similar to benthic samples, the taxonomic compositions of drift in the nine tributaries were
primarily composed of chironomids, with Tyone River again an exception (Figure 5.8-12; Table
5.8-4). Mean relative abundances for chironomids ranged from 3.7 percent at Tyone River to
72.8 percent at Watana Creek. In contrast, while the Tyone River site was mostly comprised of
zooplankton, with mean relative abundance of 78.6 percent (Figure 5.8-12; Table 5.8-4).
Deadman Creek had the next lowest chironomid relative abundance in drift, at 48.2 percent, with
a higher Other Diptera component (28.8 percent), attributed to the presence of drifting Simulium
sp. blackfly larvae. The Oshetna site showed the highest mean relatively abundances for both
mayflies (27.3 percent), largely composed of Baetis bicaudatus, and a number of Ephemerellidae
and Heptageniidae taxa. Both Jay and Butte creeks revealed nearly one-third of their drift
compositions were non-insects, largely ostracods.
Mean drift organic matter estimated from the drift samples collected from the tributary sites
ranged from 0.14 mg/ft3 at Butte Creek, to 1.16 mg/ft3 at Oshetna River (Figure 5.8-13; Table
5.8-5). Four of the nine sites, Fog Creek, Kosina Creek, Oshetna River, and Tyone River, had
mean drift OM amounts in excess of 0.5 mg/ft3. At Fog Creek, the CPOM component comprised
roughly two-thirds of the drift OM; at Deadman, Watana, and Butte creeks, FPOM contributions
were higher than CPOM (Figure 5.8-13; Table 5.8-5). Drift CPOM was approximately equal to
the FPOM component at the other five sites.
5.8.1.3. Water quality
Water quality results are presented in Table 5.8-3 and Table 5.8-6. TP levels ranged from 2.61
micrograms per liter (µg/L) at Devil Creek, to 56.72 µg/L at Oshetna River. All sites except for
Oshetna River had TP levels below 10 µg/L (Table 5.8-3). SRP levels ranged from <1 µg/L
(undetectable) at Butte, Kosina, and Fog creeks, to 6.18 µg/L at Jay Creek. Other sites showed
SRP levels between 1.77 to 2.77 µg/L. Ammonia as nitrogen was undetectable at all tributary
sites (<10 µg/L). For nitrates+nitrites, levels ranged from <10 µg/L (undetectable) at Tyone
River, to 48.67 µg/L at Devil Creek. Higher nitrate+nitrite levels were also seen at Oshetna
River (37.93 µg/L) and Jay Creek (36.74 µg/L). Levels of total Kjeldahl nitrogen (TKN) were
undetectable (<200 mg/L) at all sites, except for Tyone River, which measured at nearly 700
mg/L. DOC levels ranged from 0.85 mg/L at Watana Creek, to 13.60 mg/L at Tyone River.
Other sites showed DOC levels between 0.93 and 3.53 mg/L.
For in-situ measurements, temperatures ranged from a low of 6.2˚C at Oshetna River, to a high
of 16.8˚C at Tyone River (Table 5.8-6). Oshetna River is likely lower in temperature due to its
glacial source, whereas the Tyone River site was located downstream from the outfall of the
shallow Lake Tyone. Deadman Creek, another tributary with lake outflow, also recorded a
higher temperature of 11.5˚C. Temperatures at other sites measured between 7 and 10˚C.
Specific conductance measures ranged from 52 microsiemen per centimeter (µS/cm) at Kosina
Creek, to 309 µS/cm at Tyone River, with other sites not exceeding 130 µS/cm. General
conductance followed the same trends. Measurements of pH ranged from 6.23 at Devil Creek, to
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8.6 at Tyone River. Redox potential (ORP) ranged from 103.1 at Jay Creek, to 187.8 at Devil
Creek. Dissolved oxyen (DO) levels ranged were generally high, ranging from 9.62 mg/L (at 83
percent saturation) at Watana Creek, to 13.56 mg/L at Oshetna River. Lower levels at Watana
Creek could be related to the presence of a beaver pond in the off-channel at the site. Lastly,
turbidity was low at most sites, with the highest levels recorded in lake-fed Tyone River (8.3
NTU, dark with tannins from the lake) and the glacially-fed Oshetna River (16.1 NTU).
5.8.2. Lakes
5.8.2.1. Benthic sampling
Petite ponar samples collected in July 2014 from the three lakes feeding the Tyone River system
in the Upper Susitna River Basin revealed that benthic communities were largely determined by
the depth from which they were sampled (Table 4.10-2). Lower densities were recorded at sites
with greater depths (75 ft or greater). One exception was LTY-1, the shallowest site in Tyone
Lake at 4.5 ft deep, with a mean benthic density of 1,119 individuals/m2 (Table 5.8-7). Mean
benthic densities from the nine sites within the three lakes ranged from 75 individuals/m2 at
LSU-1 in Susitna Lake (78 ft), to 7,550 individuals/m2 at LTY-3 in Tyone Lake (21 ft; Figure
5.8-14; Table 5.8-7). Ponar grabs at LSU-1 were nearly devoid of organisms, netting only 7
organisms total among the five replicate grabs.
The pattern for mean taxa richness was similar to density, with sites sampled at greater depths
displaying lower mean and total taxa richness values (Figure 5.8-15; Table 5.8-7). Mean taxa
richness within the lake sites ranged from 1 taxa at LSU-1, to 15.2 taxa at LSU-2 in Susitna Lake
(22 ft). Shallow sites displayed an average of 10 or more taxa, and a total number of taxa greater
than 20, whereas deeper sites averaged less than 6 taxa, and 11 or less total taxa. For shallow
sites, chironomid taxa contributed a majority to the overall taxa richness values, both mean and
total (Figure 5.8-15; Table 5.8-7).
Community compositions within the nine lake sites revealed most sites were primarily composed
of chironomids and non-insect taxa (Figure 5.8-16; Table 5.8-7). Mean relative abundances for
chironomids ranged from 0 percent at LSU-1, to 65.7 percent at the upper site in Lake Louise
(LLO-3). Similar to the trend with other metrics, sites sampled at greater depths displayed lower
mean percent relative abundances of chironomids (0 – 10.2 percent), but higher contributions of
non-insects (90 – 100 percent). The lower site in Susitna Lake (LSU-1) contained only a few
ostracod individuals in total. Sites in shallow waters had greater contributions of chironomids
(23.6 – 65 percent), with the remainder being non-insect taxa (32.2 – 68.3 percent) (Figure 5.8-
16; Table 5.8-7). Non-insect taxa present at these lake sites were largely nematode worms, along
with oligochaete worms, fingernail clams (Sphaeriidae), and ostracods. Some of the shallow
depth sites also showed a number of Valvata snails.
For the nine lake sites, the relative abundances of functional feeding groups showed a dominance
of collector-gatherers, ranging from 27.5 percent at LSU-2, to 80.6 percent at the middle sites in
Lake Louise (LLO-2), and ultimately 100 percent at LSU-1 (Figure 5.8-17; Table 5.8-7).
Collector-filterers were mostly due to larger contributions of Sphaeriidae. Scrapers can be
attributed to the presence of snails, such as Valvata. Parasites were largely due to the larger
contributions of nematode worms present in samples.
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Mean benthic organic matter estimated from the Ponar samples from the lake sites ranged from
14.9 g/m2 at the upper site in Susitna Lake (LSU-3), to 290 g/m2 at the upper site in Lake Louise
(LLO-3) (Figure 5.8-18; Table 5.8-8). At the shallow sites, mean benthic OM was greater than
deep water sites, exceeding 50 g/m2, with the exception of LTY-3, which recorded only 17.2
g/m2. At all lake sites, benthic OM was most composed of the FPOM component (Figure 5.8-18;
Table 5.8-8).
At each lake site, qualitative benthic sampling was conducted with a D-net at the nearest
shoreline, generating a taxa list for the littoral zone at each location. In comparison to the Ponar
samples, shoreline areas possessed a more diverse assemblage of macroinvertebrate taxa. Total
taxa richness for shoreline areas ranged from 24 taxa at LSU-2 to 39 taxa at LSU-1 (Figure 5.8-
18; Table 5.8-9). Shoreline EPT taxa richness, nearly non-existent in Ponar samples, ranged
from 1 taxon at LTY-1 and LSU-2, to 7 taxa at LLO-2. Chironomid taxa richness along
shorelines in the lakes ranged from 9 taxa at LLO-1 and LLO-3, to 17 taxa at LTY-3 and LSU-1
(Figure 5.8-18; Table 5.8-9).
Community compositions within the shorelines of the nine lake sites revealed most sites were
primarily composed of chironomids and non-insect taxa, but with notable contributions from
EPT taxa as well (Figure 5.8-19; Table 5.8-9). Relative abundances for chironomids ranged
from 6.9 percent at LSU-2, to 72.1 percent at LTY-1. Non-insect taxa contributions ranged from
26.6 percent at LTY-1, to 91.2 percent at LSU-2. Non-insects assemblages consisted of
ostracods, the gammarid Hyalella sp., several snail taxa, oligochaete worms, water mites (Acari),
and nematode worms. The percent contribution of mayflies in shoreline communities at the nine
lake sites was highest at sites within Lake Louise, ranging from 11.7 percent to 31.2 percent,
attributed to the baetid Procloeon sp.
For the nine lake sites shorelines, the relative abundances of functional feeding groups showed a
dominance of collector-gatherers, ranging from 45.7 percent at LTY-2, to 78.9 percent at LTY-1
(Figure 5.8-20; Table 5.8-9). Scraper contributions along the shorelines ranged from 1.2 percent
at LSU-1, to 39 percent at LTY2, comprised of snails from families of Valvatidae, Lymnaeidae,
and Planorbidae. Predator contributions along shoreline habitat ranged from 1.6 percent at LSU-
2, to 18.6 percent at LLO-2.
5.8.2.2. Plankton Tows
Plankton tows collected in July 2014 from the three lakes feeding the Tyone River system in the
Upper Susitna River Basin revealed a notable amount of zooplankton available in the water
column, as compared to benthic sampling. Mean plankton tow density estimates among the nine
lake sites ranged from 47,513 individuals/m2 at the lower site in Tyone Lake (LTY-1), to
253,697 individuals/m2 at the deepest site in Lake Louise, LLO-2 (Figure 5.8-21; Table 5.8-10).
Mean dry weight biomass estimates, calculated from average body lengths of zooplankters,
ranged from 149.1 mg/m2 at LTY-1, to 553.4 mg/m2 at LTY-2 (Figure 5.8-22; Table 5.8-10).
For both density and biomass estimates, higher amounts were recorded in the middle and upper
extent of Tyone Lake (LTY-1 and LTY-2) and the lower extent of Susitna Lake (LSU-1), and at
the middle site in Lake Louise, LLO-2.
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Mean taxa richness of zooplankton collected in the nine lake sites in July 2014 ranged from an
average of 2.8 taxa at LLO-1, to an average of 5 taxa at LTY-1 (Table 5.8-10). Total taxa
richness was limited to 4 to 6 taxa, due to the presence of earlier life stages of copepods, nauplii
and copepodites. As such, most copepods could only be identified to order. A total of 8
cladoceran taxa were present throughout all samples, although only a maximum of 4 cladoceran
taxa were found together at a site (Table 5.8-10).
The taxonomic composition of zooplankton by density revealed that a majority of zooplankton
collected in July 2014 were copepods. Copepod contributions to mean density ranged from 75.1
percent at LTY-2, to 99 percent at LLO-1 (Figure 5.8-23; Table 5.8-10). Cladoceran densities
were highest at sites within Tyone Lake, ranging from 11.5 percent at LTY-3, to 24.9 percent at
LTY-2, with Daphnia longiremis being the most prominent cladoceran taxa observed. The
taxonomic composition of zooplankton by weight (biomass) showed a similar trend. Copepod
contributions to mean biomass ranged from 64.5 percent at LTY-2, to 97.7 percent at LLO-1
(Figure 5.8-23; Table 5.8-10). Cladoceran biomass was highest at sites within Tyone Lake,
ranging from 17.4 percent at LTY-1, to 35.5 percent at LTY-2, with contributions from Daphnia
longiremis, D. ambigua, and Eubosmina longispina.
5.8.2.3. Water quality
Water quality results are presented in Table 5.8-11 and Table 5.8-12. Depth profiles are
graphically presented in Figures 5.8-24 through 5.8-27.
For measurements of light penetration in July 2014, the average Secchi depth in Tyone Lake
ranged from 12.5 ft to 14.25 ft, and the calculated euphotic zone depth ranged from 16.9 ft to
22.9 ft (Table 5.8-11). In Susitna Lake, the average Secchi depth ranged from 18.6 ft to 21.5 ft,
with the calculated euphotic zone depth ranging from 32.1 ft to 46.9 ft (Table 5.8-11). In Lake
Louise, the average Secchi depth ranged from 24.75 ft to 27 ft, with the calculated euphotic zone
depth ranging from 41.8 ft to 44.9 ft (Table 5.8-11).
Total phosphorus levels in July 2014 generally ranged from 5.3 µg/L to 11.5 µg/L, with the
exception of a peak of 15.15 µg/L at LLO-2 near the bottom (129 ft). TP levels appeared to
show increases near the bottom (Table 5.8-12). SRP levels generally ranged from <1 µg/L
(undetectable) to 4 µg/L, with the exception of 7.90 µg/L at LLO-2 near the bottom.
In July 2014, ammonia as nitrogen was undetectable at most surface and euphotic depths (<10
µg/L), but increased substantially near the bottom of the lake sites, ranging from 11.2 µg/L near
the bottom of LLO-1 (95 ft) to 138 µg/L near the bottom of LSU-1 (75 ft) (Table 5.8-12). For
nitrates+nitrites, levels ranged from <10 µg/L (undetectable) at most sites and depths, but with
increased levels near the lake bottom at sites with greater depths, ranging from 11.2 µg/L at
LLO-1 near the bottom, to 52.9 µg/L near the bottom at LSU-1 (Table 5.8-12). Levels of TKN
were ranged from 325 mg/L to 620.5 mg/L, with no discernable pattern.
DOC levels in July 2014 ranged from 7.13 mg/L to 10.4 mg/L, with no discernable pattern
(Table 5.8-12). Alkalinity levels appeared to increase moving from Tyone Lake to Lake Louise.
Alkalinity in Tyone Lake averaged 56.8 mg/L; in Susitna Lake, 61.8 mg/L; and in Lake Louise,
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62.9 mg/L (Table 5.8-12). Chlorophyll-a levels ranged from <0.3 µg/L (undetectable) to 4.8
µg/L (measured at LLO-1 near the bottom), with no discernable pattern (Table 5.8-12).
Depth profiles in the lakes showed temperatures in July 2014 ranged from 14 – 16˚C near the
lake surfaces, decreasing at about 10 – 15 ft deep (Figure 5.8-24). At deeper sites, temperatures
continued to decrease until reaching a low of 5 – 8˚C at depths of 60 – 70 ft deep. PAR
measurements showed a rapid decrease in light levels from the surface ambient levels,
approaching the 1 percent of ambient light level around 30 – 40 ft at deeper sites, which is in
general agreement with the calculated euphotic zone depths in Table 5.8-11 (Figure 5.8-24).
DO levels ranged were generally high in July 2014, ranging from 9 – 10 mg/L and higher percent
saturations until reaching near the bottom, where DO levels dropped rapidly (Figure 5.8-25). At
deeper sites, DO levels approached 0 mg/L (and 0 percent saturation). At LTY-1, the lower site
in Tyone Lake, DO levels were supersaturated, up to nearly 104 percent. The site was located in
the shallow end of Tyone Lake, with maximum depths of only 4.5 ft, with large mats of
macrophytes growing in the area. Water quality measurements were taken in one of the few
areas where the lake bottom was accessible. The surrounding aquatic vegetation would explain
the supersaturation. The water can become supersaturated when oxygen is produced by aquatic
vegetation more quickly than it can escape into the atmosphere.
Conductance measures differed among the three lakes in July 2014. Specific conductance
ranged from 325 – 330 µS/cm in Tyone Lake, 315 – 320 µS/cm in Susitna Lake, and around 157
µS/cm in Lake Louise (Figure 5.8-26). At several sites, conductance values began to rapidly
increase at the lake bottom. General conductance followed the same trends (Figure 5.8-26).
Measurements of pH revealed the lake waters to be fairly alkaline in July 2014, ranging between
a pH of 7 and 8. Higher pH was recorded near the surface and first 10 – 20 ft, peaking around
8.2 (Figure 5.8-27). In Tyone Lake, pH levels stayed at 8.2 until decreasing at the lake bottom,
with the exception of the shallow LTY-1, which maintained a pH of 8.5. In Susitna Lake, pH
levels peaked at around 8.2 at depths of 10 – 20 ft, before gradually declining to near the lake
bottom. Sites with greater depths (LSU-1 and LSU-3) both saw a slight increase in pH at the
bottom (Figure 5.8-27). In Lake Louise, pH levels at LLO-1 peaked at around 8.2 at depths of
15 – 20 ft, before gradually declining to 7.5 at 96 ft deep. At LLO-2, pH was 8.2 at the lake
surface, and gradually declined to 7.4 at the 96 ft depth (Figure 5.8-27). At LLO-3, a shallow
site, pH rose to 8.2 at 16 ft deep, before decreasing to 7.4 at the bottom (17 ft). Redox potential
(ORP) within the three lakes in July 2014 ranged from 300 – 390 mV (Figure 5.8-27). Most sites
recorded gradual increases in ORP with increasing depths, before rapidly decreasing at the lake
bottom.
6. DISCUSSION
6.1. Benthic Macroinvertebrate Communities
The remaining results from the 2013 benthic macroinvertebrate sampling efforts addressed
trends in adult emergence of aquatic insects from the benthic communities, and the dynamics of
the benthic macroinvertebrate community on pieces of woody debris. As was discussed in the
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ISR (Section 6; AEA 2014a), collection efforts in 2013 found that the traps were prone to
damage from wildlife, and were stranded on shorelines due to rapid changes in flow levels or
from disturbances by boating activities. Out of 65 potential samples over the sampling season,
18 (28 percent) were lost, 20 (31 percent) were retrieved from a stranded or disturbed state, and
27 (41 percent) samples were collected intact. Due to the prolonged set times of two weeks or
longer, the exact timing occurrence of a disturbance within that period was unknown, making
any sample data that could be retrieved from the trap bottle qualitative, since the total sampling
time was in question. The occurrences of losses and stranded or disturbed samples resulted in
coverage gaps at many of the sampling sites, making it difficult to assess trends or patterns in
emergence timing for the various insect taxa present. Despite these difficulties, emergence traps
did collect valuable information when they were undisturbed during a sampling period.
From the data collected in 2013, emergence sampling revealed several trends. At sites above
Devils Canyon, main channel habitats had higher daily emergence densities than other
macrohabitats, with peaks in the latter half of July to early August. However, at Middle Reach
sites below Devils Canyon (Indian River and Whiskers Slough Focus Areas), upland sloughs and
tributary mouths were generally higher in daily emergence densities compared to main channels
and side channels, and in the Montana Creek study station in the Lower Reach, daily emergence
densities were also higher in the upland slough site compared to those recorded for main and side
channel habitats. Overall emergence taxa richness during 2013 was also variable among reaches
and sampling periods, again showing peaks of emergence largely in July and August.
Overall adult emergence community composition measures revealed that all sites were
dominated by aquatic taxa, and were comprised mostly of chironomids, which were generally 50
percent or higher at most sites (Tables 5.1-3 to 5.1-12). The contribution of EPT taxa to
community compositions appeared to be influenced by macrohabitat types, with higher relative
abundances of emerging stoneflies (primarily Chloroperlidae and Perlodidae) at main channel
and side channel sites, and greater contributions of caddisflies in the mouths of the named
tributaries (Indian River, Tsusena Creek, Whiskers Creek, and Montana Creek). In samples that
were stranded out of the water upon retrieval, higher relative abundances of terrestrial taxa were
often recorded, generally marked by increased relative abundances of Hemiptera (true bugs),
Hymenoptera (sawflies, wasps, bees, and ants), and Other Diptera (true flies) (Tables 5.1-3 to
5.1-12), indicating that even when onshore, the traps can capture terrestrial shoreline insects.
These results indicate that the emergence traps do function as intended when successfully
deployed and left undisturbed during their deployment. The main issue appears to be that traps
are left unobserved for long periods of time, during which they have increased chance of
disturbance, the timing of which is unknown. To resolve the concerns with losses and stranding,
modifications were proposed to redesign adult emergence traps for more successful deployments,
(ISR Part C, Section 7.1.2.1; AEA 2014a). Proposed emergence trap modifications included: 1)
increased floatation to prevent sinking and/or capsizing and 2) improved anchoring and
deployment. In 2014, emergence traps were used in a limited capacity, collecting emergent
adults for use in the stable isotope analysis study objective. As part of the “improved
deployment” modification, emergence traps were deployed at selected sites for 24-48 hr
durations during each sampling event. Traps were able to collect enough specimens for the
needs of stable isotope analysis, and losses limited to a single trap being damaged by bears. No
samples were stranded due to the short deployment time. Therefore, in addition to a physical
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redesign of the traps to prevent sinking, deployment methods could be altered to sample for
shorter durations (24-48 hrs), but more frequently (approximately 2-week intervals) in order to
provide consistent samples by minimizing losses due to unobserved disturbances or stranding.
Collection of benthic macroinvertebrates from woody debris in 2013 yielded 155 samples from
16 of the 20 study sites, an average of about 3 samples per site per sampling event. Pieces
mostly were located in tributary mouths and off-channel macrohabitats. Main channel sites
rarely provided suitable LWD, as most wood was located stranded around the ordinary high
water mark (OHWM).
Samples collected from wood produced valuable information on the utility of the substrate to
benthic macroinvertebrate communities. Results revealed that densities on wood were higher
overall in larger tributary mouths and off-channel sites compared to main channel and most side
channel sites. Mouths of larger named tributaries (Indian River, Montana Creek, Tsusena Creek,
Whiskers Creek) had among the highest averaged densities, comparable to those seen on cobble
substrates at those sites. Side channel macrohabitat sites recorded higher density estimates at
RP-81 and RP-104 compared to side channels at stations farther upstream. Within other
macrohabitats, overall densities on woody debris were often higher than the benthic densities
recorded at the same sites.
This suggests that woody debris, when present, can act as an attractant to many
macroinvertebrate taxa. Overall benthic taxa richness on woody debris during 2013 was highest
in the larger tributary mouths, comprised of more than 50 percent chironomids. Many of the
chironomid taxa identified were wood-boring in habit, indicating these taxa actively seek out
wood to colonize, due to their particular specialization. While EPT taxa richness was relatively
low on woody debris, the contribution of EPT taxa to community compositions was generally
higher at sites with consistently suitable woody debris available, suggesting that wood debris
may need to be more established in the water within a site to attract EPT taxa to colonize it.
The metrics calculated from the taxonomic abundance data are the first step in the data analyses
planned for the benthic macroinvertebrate data collected for this study. The 2013 benthic
metrics can begin to describe the benthic community structure and function. Ultimately, the data
collected in 2013 and the future data collection efforts will be combined to provide the
information needed for the additional statistical analyses, the results of which will be provided in
the Updated Study Report.
6.2. Drift of Benthic Macroinvertebrates
Results from the drift sampling effort in 2014 showed trends similar to those seen in 2013, with
some expected degree of annual variability for sites. Generally, results from both years showed
noticeable differences in several metrics between sites characterized as non-flowing habitats that
were sampled with plankton tows (side sloughs, upland sloughs) compared to flowing water
habitats that were sampled with the drift nets, i.e., mainstem macrohabitats (main channel and
side channel habitats) and tributary mouths. Mouths of the tributaries (RP-184-1, RP-141-1, RP-
104-1, RP-81-2) showed higher overall drift densities as compared nearby main channel and side
channel sites, suggesting their role as contributing sources of additional macroinvertebrates
drifting from rich benthic communities at upstream locations. Upland sloughs and side sloughs
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showed among the highest overall averaged densities by volume (per cubic foot) via plankton
tows in 2014, a similar trend also seen in 2013, and likely due to the inherent differences in
sampling devices and the water volumes they sample (drift nets capturing flowing water versus
plankton tows subsampling a non-flowing volume of water).
Overall drift taxa richness during 2014 was highest in tributary mouths and main channel habitat,
followed by side channels; fewer taxa were captured in plankton tows taken in off-channel
habitats (side sloughs and upland sloughs). Both the EPT taxa richness and overall chironomid
taxa richness were higher in tributaries and main channel habitats than in the slough habitats.
All sites sampled in 2014 showed community compositions largely comprised of chironomids,
with flowing water habitats featuring higher contributions of EPT taxa, compared to that seen in
sloughs. Sites above Devils Canyon showed small relative abundances of zooplankton (0- to 13
percent), with higher averages actually seen in main and side channels (9- to 17 percent),
whereas at sites below Devils Canyon, larger relative abundances of zooplankton (averages
ranging from 2.5- to 34 percent) were generally limited to slow water habitats and conditions,
especially at upland slough sites.
The various metrics calculated from the drift sample and plankton tow data for 2013 and 2014
provide two years of valuable baseline information on the dynamics of drifting invertebrates
within the Middle and Lower Susitna River. Such results successfully highlight the differences
in potential food resources available to fish in flowing-water macrohabitats compared to the
slower off-channel macrohabitats, as well as longitudinal differences among stations, and
seasonal and annual differences. This two year effort provides the information needed for the
additional statistical analyses required to characterize drift and its availability to fish as a food
resource, the results of which will be provided in the Updated Study Report.
6.3. Trophic Modeling
The bioenergetics model results indicated that feeding rate was a primary factor limiting the
growth of juvenile Coho Salmon, and temperature and food quality were of secondary
importance. This is consistent with general bioenergetics theory: across the range of
temperatures typically observed in Alaskan streams and rivers, the growth of juvenile Chinook
and Coho salmon is expected to be limited mostly by feeding rate (Beauchamp 2009). However,
juvenile Chinook Salmon fed near their physiological maximum rates and were primarily limited
by temperature and food quality during early summer, before becoming more food-limited
during late summer. Similar results have been demonstrated in other situations when
temperatures are cool and food is abundant. For example, a bioenergetics analysis and field
experiment in the Chena River demonstrated that juvenile Chinook Salmon fed close to their
theoretical maximum consumption rate (P near 1), and temperature was the primary limitation on
growth (Perry 2012). In support of this model result, experimental addition of pelleted fish food
to treatment reaches did not enhance the growth rate of salmon in those reaches in comparison
with growth rates measured in control reaches. Likewise, heterogeneous stream temperatures in
Southwest Alaskan streams caused high variability in age-0 Coho Salmon growth, and these
differences were amplified by the ability of faster-growing coho to consume salmon eggs during
their first growing season (Armstrong et al. 2010). Temperature has also been shown to be a
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primary constraint on the growth of some Arctic Grayling populations in Interior and Arctic
Alaska (Deegan et al. 1999; Dion and Hughes 2004).
When abundant food resources are distributed in habitats with suboptimal temperatures for
growth, juvenile salmon and other fishes have been observed to behaviorally thermoregulate to
maximize their growth rates (Wurtsbaugh and Neverman 1988, Armstrong et al. 2010). This
study provided some limited evidence that juvenile salmon may display this strategy in the
Susitna River, but it did not appear to be widespread. Both the PIT tag study (Study 9.6) and the
stable isotope analysis (Section 5.4.2) provided evidence of relatively strong site fidelity by
rearing juvenile salmon. Based on an analysis of provisional PIT tag data collected within the
River Productivity study area, the vast majority (75/78) of juvenile Chinook and Coho salmon
tagged during 2013 and 2014 and later recaptured were found in the same habitat in which they
had previously been marked. This analysis did not include PIT tags recorded by fish swimming
past fixed antennas, only events when the fish were recaptured and reweighed. The pattern was
consistent whether days, weeks, or months elapsed between capture events. While these results
do not necessarily indicate that fish remained in the same habitat between recaptures, they can be
explained most parsimoniously by site fidelity. Further, the isotopic signatures of juvenile
salmon were similar to those of other salmon captured in the same macrohabitat and to the basal
nutrient sources within that habitat. Based on the isotopic turnover time of fin tissue, this
suggests that most fish fed in the habitat where they were captured for at least 1-2 weeks prior to
capture. Both the PIT tag study and the stable isotope analysis provided evidence of occasional
fish movements among macrohabitats; however, fish did not appear to move frequently.
This study documented relatively limited opportunities for fish to achieve large growth
advantages through behavioral thermoregulation. Behavioral thermoregulation should be most
advantageous when abundant food resources are available in a cold (or very warm) habitat that is
adjacent to another habitat with more optimal temperatures. In the Susitna River, this situation
could arise when salmon spawn in cold habitats like sloughs fed by hyporheic-flow. Within the
broader River Productivity study area, however, salmon did not generally spawn in the coldest
sites (Figure 5.4-13). In fact, the site where the most consumption of salmon eggs was
documented was the relatively warm Indian River tributary mouth (Site RP-141-1). While
behavioral thermoregulation was not observed during this study, most of the differences in
growth rates documented in this study could be explained more simply by the temperature and
food availability within each given site.
The growth rate potential analysis illustrated potential relationships between measurable habitat
characteristics and fish growth, based on previously published experiments. The growth rates
predicted by the model were broadly similar to the growth rates observed in this study, and the
model identified certain known hotspots for juvenile salmon, such as the Indian River tributary
mouth (RP-141-1) as high-growth habitats. However, this application of the growth rate
potential analysis also revealed three key challenges for applying such models in large,
heterogenous, glacial rivers. First, the drift foraging submodel assumed that juvenile salmon fed
solely on invertebrate drift. However, the stomach content and stable isotope analysis showed
that salmon eggs were a very important diet item at some sites, and the growth rate potential
analysis did not take this into account. Also, many salmon were captured in slow-velocity
habitats, including upland sloughs, side sloughs, and slowly flowing tributary mouths. Salmon
are likely switch to search feeding in these habitats; however, this behavior is not accounted for
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in the standard drift foraging model framework (Hughes and Dill 1990). Novel foraging models
allowing fish to switch between drift and search feeding modes may be worth investigation for
future applications in the Susitna Basin (Harvey and Railsback 2013). Finally, foraging
dynamics in the shallow margins of mainstem rivers are poorly understood, and most existing
drift-feeding research has focused instead on small streams. The growth rate potential model
generally predicted that main channel and side channel habitats would not support positive
salmon growth, due largely to their high velocities. However, this study provides evidence that
juvenile salmon do utilize main channel and side channel habitats in the Susitna River for
feeding and rearing, and in some cases achieved faster growth in these habitats than in cooler,
slowly flowing sloughs. As currently formulated, growth rate potential models based on drift
foraging are most likely to be useful in tributaries to the Susitna River. To fully account for the
diversity of habitats and feeding modes utilized by juvenile Chinook and Coho salmon, in the
Susitna River any future development of the growth models should consider incorporation of
feeding mechanism in both sloughs and mainstem habitats
6.4. Food Web Analysis via Stable Isotope Analysis and Fish Diet
Analysis
6.4.1. Energy flow from algae and organic matter to freshwater invertebrates
Various trends emerged from the stable isotope analysis of lower food web components that are
potentially significant in synthesizing findings from previous studies on energy flow through
riverine food webs. In alignment with numerous other studies (Kline et al. 1990, France and
Cattaneo 1998, Finlay 2001, Finlay 2004, Hadwen et al. 2010), algae samples were highly
variable in 13C signatures compared to terrestrial OM. This overall variability appeared to be at
least partially explained by macrohabitat type, where algae samples from the glacially influenced
main and side channels were consistently the most 13C-enriched, followed by tributary mouths,
and finally by slough habitats (Figure 5.4-21). This same pattern was also evident for freshwater
invertebrates (Figure 5.4-21). There are many possible interrelated environmental factors that
control 13C in aquatic plants and algae, such as temperature, water velocity, partial pressure of
carbon dioxide (pCO2), and carbon source 13C (Finlay 2004). Water velocity has often been
cited as a major factor contributing to isotopic variability in aquatic primary producers,
predominantly by effects of boundary layer thickness on CO2 diffusion. In this case, slow
flowing water results in thicker boundary layers around algae, thereby slowing CO2 diffusion and
reducing discrimination against the heavier 13C (Finlay et al. 1999, 2002). If this effect were a
predominant driver of 13C patterns, algae and their primary consumers would exhibit 13C-
depleted tissues in faster currents relative to those in slower currents (Trudeau and Rasmussen
2003).
Throughout macrohabitats in the Susitna, however, algae and freshwater invertebrates seemed to
show an opposite trend, where those in faster main and side channel habitats were more 13C-
enriched relative to generally slower tributary mouths, followed by sloughs with the slowest
current velocities. It is possible that this pattern is explained by greater retention and availability
of terrestrial OM in slow-water habitats. As this material is broken down by instream microbes,
the 13C-depleted CO2 respired in the process is made available for uptake and assimilation by
algae (France and Peters 1997, France and Cattaneo 1998). In habitats with higher water
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velocity, less organic matter is retained and available for microbial respiration, resulting in algae
with relatively enriched 13C values (France and Peters 1997, France and Cattaneo 1998).
Results from linear regressions of aquatic invertebrate – source 13C showed that site-specific
algae 13C predicted 13C for all aquatic invertebrate feeding groups better than did terrestrial
OM 13C, suggesting that primary consumers were predominantly assimilating instream sources
of carbon. A number of authors (Junk et al. 1989, Sedell et al. 1989, Gaedke et al. 1996, Lewis
et al. 2001) have observed that instream autotrophy is often the predominant carbon pathway in
river food webs and despite the prevalence of terrestrial OM, many invertebrates rely on
instream algae presumably because is more labile with a higher nitrogen content . That collector,
grazer, and shredder feeding group 13C was better predicted by algae 13C in this system
follows reports of feeding plasticity and a general reliance on instream autotrophy by the same
groups in a number of other systems (Koslucher and Minshall 1973, Palmer et al. 1993, Miller et
al. 1998, Zah et al. 2001).
6.4.2. Energy flow to focal salmonid species
Mixing model results suggested that freshwater invertebrate prey were the most important diet
items for all salmonid target species overall (Tables 5.4-4 to 5.4-6, Figures 5.4-25 to 5.4-28).
Freshwater prey were more important to juvenile salmon and Rainbow Trout diets in 2014
relative to the previous year, whereas the role of marine prey was reduced. This change was also
reflected in the drastic decrease in salmon eggs found in stomach content samples in 2014.
Arctic Grayling relied most heavily on freshwater and least on marine energy sources relative to
other target fish species. The stomach content analysis revealed that Chinook Salmon, Coho
Salmon, and Rainbow Trout exhibited an ontogenetic dietary shift to salmon eggs that occurred
at approximately 55-85 mm FL.
Robust interpretation of stable isotope diet models requires diet sources to be isotopically distinct
enough in order to differentiate their importance in consumer diets (Moore and Semmens 2008).
Freshwater and terrestrial sources were often isotopically similar within sites, with correlations
between posterior estimates of these two sources ranging between r = -0.39 to -0.97. In cases
where sources were highly correlated and the model was unable to discern source contributions
from isotope data, priors from stomach content data were more influential in guiding
proportional contribution estimates (Moore and Semmens 2008). The uncertainty inherent in the
isotope data is reflected in the relatively large credible intervals for freshwater and terrestrial
source contributions (Figures 5.4-25 to 5.4-28). The stomach content data provided additional
specificity in comparing the importance of freshwater and terrestrial prey, as well as the relative
importance of aquatic larvae and pupae vs. terrestrial adult life-stages of freshwater
invertebrates.
Taking these factors into account, comparisons of diet model results across macrohabitats
(Figures 5.4-25 to 5.4-28) generally show a high degree of overlap between model estimates for
fish diets among the different macrohabitat types. Both freshwater and terrestrial prey played
similar roles in diets across the heterogeneous macrohabitats sampled, except where salmon eggs
made up a significant proportion of diets. In 2013, salmon eggs were consumed in all
macrohabitat types sampled (upland slough, tributary mouth, and side channel), however
tributary mouths were the most important sites for egg consumption. In 2014, egg consumption
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in tributary mouths was reduced compared to the previous year, and conversely was higher in
upland sloughs and the side slough site for juvenile salmon (Figures 5.4-25 and 5.4-26). No
stable isotope evidence exists to suggest that any target fish species fed on salmon eggs during
any sampling period in glacial-fed main channel habitats, but salmon eggs were consumed by
juvenile salmon to some extent in glacial-fed side channels (Figures 5.4-25 and 5.4-26). Surveys
of spawning salmon in the Middle and Lower Susitna River in 2013 and 2014 confirmed that
tributary mouths were used for spawning locations, and to lesser extents, slough and side channel
habitats (AEA 2014b). The use of tributary mouths by spawning salmon in 2013 parallels
consumption of salmon eggs by juvenile salmon and Rainbow Trout in this macrohabitat type,
and suggests that in the Susitna River, tributary mouths in particular can be important hotspots of
high quality marine prey pulses to these fish species.
As expected, marine-derived food subsidies appeared to be much more important below Devils
Canyon. Fish consumption of salmon eggs is likely extremely limited above this barrier due to
the low densities of spawning anadromous Chinook Salmon and the absence of the primary
ovivorous species, Rainbow Trout and Coho Salmon. Stomach contents of Arctic Grayling and
juvenile Chinook Salmon collected above the canyon (Stations RP-173 and RP-184) did not
include any salmon eggs. Below Devils Canyon, however, no consistent or discernible diet
pattern was observed relating to distance from the river mouth (Figures 5.4-25 and 5.4-26).
Mixing model means and credible intervals grouped by macrohabitat type and season from
among all reaches generally overlapped to such an extent as to suggest that no strong upstream to
downstream trend in food source contributions existed, or at least to obscure a more definitive
trend (Figures 5.4-25 and 5.4-26). It is likely that the combination of seasonal and
environmental drivers acting on instream production and on the input of subsidized material
within individual sites of the same macrohabitat classification are unique enough to produce diet
patterns that are inconsistent with a longitudinal effect (Poole 2002, Stanford et al. 2005). For
example, while juvenile salmon rearing in all sampled tributary mouths in 2013 were supported
by marine-derived food, the direction and magnitude of those contributions varied over time
between tributary mouth sites (Figures 5.4-25 and 5.4-26). This resulting effect likely depends
on a large range of possible factors such as non-overlapping spawning habitat preferences and
run timing between different species of adult salmon (Wipfli and Baxter 2010; AEA 2014b).
Mixing models estimated that freshwater prey contributions remained substantial during all
seasons at most sampling sites, and often either decreased in importance from spring to fall or
were least important during the summer sampling period (Figures 5.4-25 to 5.4-28). Chinook
Salmon diets showed a common seasonal trend where terrestrial prey were often most important
to diets during the summer sampling event. A review of studies documenting consumption of
terrestrial invertebrates by stream fishes reveals that temporal patterns are highly variable by
year and system (Wipfli 1997; Nakano and Murakami 2001; Baxter et al. 2005; Gutierrez 2011);
however, a more common pattern in higher latitude systems is an increase in the flux of
terrestrial invertebrates to streams during mid-summer when terrestrial productivity can be at its
highest (Chloe and Graman 1996; Wipfli 1997; Bridcut 2000). Because juvenile salmonids are
opportunistic predators and are known to selectively forage for terrestrial invertebrates (Hubert
and Rhodes 1989; Young et al. 1997), it is possible that a large-scale pulse of this prey subsidy
during mid-summer accounts for increased contributions to these fish populations.
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When juxtaposing resident fish energy source contributions, a large disparity between the two
fish species is evident (Figure 5.4-28). While terrestrial contributions between Arctic Grayling
and Rainbow Trout were similar across seasons, their uses of freshwater and marine sources
were significantly different. While grayling relied very little on marine sources and heavily on
freshwater, trout showed an opposing pattern (Figure 5.4-28). This difference in use between
these species has been observed in a spawning salmon creek in the Wood River system of
southwestern Alaska. Studies by Scheuerell et al. (2007) and Moore et al. (2008) both showed
that while both grayling and Rainbow Trout consumed salmon eggs, trout exploited direct
consumption of salmon eggs and carcasses more so than grayling, which tended to benefit more
directly from increased drift of benthic invertebrates that were dislodged from nest digging by
spawning female Sockeye Salmon. After increases in the availability of salmon eggs and carcass
tissue in study streams, Rainbow Trout switched away from non-egg prey while grayling
continued to feed on non-egg prey (Moore et al. 2008). Thus, these differences in foraging
patterns between both species seem to translate across systems.
Two prior juvenile salmon diet studies were conducted during 1982 at many of the same sites in
the Susitna River (ADF&G 1983; Hansen and Richards 1985), providing context for the current
study. These prior studies found that juvenile Chinook Salmon and Coho Salmon consumed
primarily aquatic invertebrates, with very little consumption of salmon eggs and no consumption
of fish (ADF&G 1983; Hansen and Richards 1985). Direct comparisons among studies are
challenging because the 1982 data were presented in terms of diet proportions by number, rather
than diet proportions by mass, the metric used in the current study, which is now preferred for
food web and energy flow studies (Chipps and Garvey 2007). However, the historic data
consistently show that salmon eggs were not consumed by juvenile Chinook or Coho salmon
with the exception of the last sampling event of the season on September 23, 1982 at Indian
River, when eggs comprised 6 percent of the Chinook Salmon diet and 2 percent of the Coho
Salmon diet (proportions by number; ADF&G 1983, Appendix Tables 3-C-12 and 3-C-19). The
average mass of a salmon egg was 23-76 times greater than that of an average terrestrial or
aquatic invertebrate food item in the current analysis; therefore, salmon eggs likely represented a
large proportion (by mass) of juvenile salmon diets during late September 1982 at Indian River
(site RP-141-1 in the current study). Although these historical data suggest that juvenile
Chinook and Coho salmon fed heavily on salmon eggs at Indian River in late September, there is
no evidence that they utilized salmon eggs during other spawning runs or at other sites within the
Susitna Basin.
Overall, energy source contributions in 2014 show that freshwater energy pathways are most
important in supporting juvenile salmon, Arctic Grayling, and Rainbow Trout feeding in multiple
habitat types of a large section of the Middle Susitna River. While freshwater prey comprised
the majority of diets, terrestrial invertebrates were also important prey items. Marine-derived
prey were generally least important in diets overall but made up substantial proportions of diets
in tributary mouth and slough macrohabitats when spawning salmon were present. While
previous studies have observed the utilization of multiple energy pathways by stream salmonids,
this study is important in demonstrating the relative importance of these pathways throughout the
habitat mosaic and across seasons in river networks.
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6.5. Organic Matter Resources
The methodology for estimating organic matter content in benthic and drift samples successfully
produced repeatable results for samples collected in 2013 and drift samples in 2014. Results
from 2013 showed that mean benthic organic matter was higher overall in samples collected with
the petite Ponar grab sampler, in mostly off-channel sites. Upland sloughs had among the
highest averaged overall total benthic OM. Flowing water sites (main channels, side channels,
and tributary mouths) typically had larger contributions of CPOM in samples than did off-
channel macrohabitat sites, which were dominated by FPOM material. A longitudinal trend was
also noted, with station-wide averages of benthic OM increasing at each station/Focus Area in a
downstream direction.
Drifting organic matter resources were collected in flowing water sites (main channel, side
channel, and tributary mouths); upland sloughs and side sloughs were primarily low-flow
habitats, often clear pool areas with little or no organic materials suspended in the water column.
As these sites are largely depositional areas, most organic matter within the sloughs was likely
represented by the benthic OM estimates. Therefore, drifting OM is more indicative of the
transportation pathway of organic matter content through the river system.
Drift OM collected in drift samples during 2013 revealed main channels had among the highest
average overall total drift OM. In 2014, differences in overall total drift OM were not evident
among the flowing water macrohabitats (main channel, side channel, and tributary mouth) as
they were in 2013. During both years, main channel and side channel sites contained a higher
component of FPOM compared to CPOM amounts, whereas tributary mouths usually contained
more CPOM than FPOM. Also, drift OM contained a higher CPOM component in collected
samples than was seen in benthic OM, with greater or equal amount of coarse material compare d
to FPOM amounts.
The estimates for organic matter content collected over 2013 and 2014 provides a strong
foundation for baseline characterization of organic matter resources that will be built upon in the
next year of study. In addition, the data collected in 2013 and 2014 and in future data collection
efforts will provide the information needed for the additional statistical analyses, the results of
which will be provided in the Updated Study Report.
6.6. Benthic Macroinvertebrates in Tributaries and Lakes above
Devils Canyon
The July 2014 survey of nine selected tributaries and three lakes in the Middle and Upper River
segments of the Susitna River basin above Devils Canyon gathered a large amount of
information within each site regarding the benthic macroinvertebrates, algae, organic matter,
water quality and nutrients, and was successful in its goal “to provide a snapshot of the pre-
Project condition of habitats in selected tributary and lake systems and the levels of productivity
available to support fish populations.”
Surveys of the nine selected tributaries in the Middle and Upper River segments of the Susitna
River revealed healthy and productive invertebrate communities residing in three different types
of streams: run-off streams, lake-influenced streams, and glacially-influenced stream. Run-off
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streams included Devil, Fog, Watana, Kosina, Jay and Butte creeks; these streams featured mean
density estimates exceeding 5,000 individuals/m2, with high diversity and high taxa richness.
Drift densities were moderately high, but very diverse with high taxa richness. Drift
compositions were largely chironomids, with some mayflies and other diptera taxa. Algal
growth on substrates was low to moderate, with mean chlorophyll-a values ranging from 0.44 to
3.5 mg/m2, and mean AFDM ranging from 0.3 to 1.85 g/m2.
Lake-influenced streams included Deadman Creek, with the sampling site located approximately
1.1 miles downstream from the outlet of Deadman Lake, and Tyone River, with the site located
5.8 miles downstream from the outlet of Tyone Lake. Both streams would be considered
extremely productive, but at differing levels. On the Tyone River, densities were high (21,730
individuals/m2), along with relatively high diversity, and high taxa richness. Community
compositions were dominated by chironomids, but with higher contributions of caddisflies
(mostly Hydroptilidae) and non-insects than other tributaries. The site on Deadman Lake
featured extremely high densities, averaging over 130,000 individuals/m2. This estimate was
largely due to one Hess sample that required less than 1 percent subsampling to obtain the 300-
count, giving it an estimated 400,000 individuals/m2. However, even if this sample is
disregarded, the average of the remaining four samples was 50,000 individuals/m2, still well
above estimates from the other tributaries. Diversity and taxa richness measures were lower than
most of the other tributaries, with the community comprised of nearly 85 percent chironomids,
higher than the other tributaries.
Both lake-influenced sites had the highest average drift densities, between 1 and 2
individuals/ft3, but with the lowest drift diversities and taxa richness. Drift compositions at
Tyone River was primarily zooplankton, likely originating from Tyone Lake, and low-flow reach
of the river in the preceding river length upstream from the site. Drift at Deadman Creek was
mostly composed of filter-feeding taxa of chironomids and black fly larvae (Simuliidae, Other
Diptera). Algal growth on substrates was highest at the lake-influenced sites, as evidenced by
chlorophyll-a and AFDM results.
Oshetna River, the only glacially-influenced stream of the nine sampled, recorded the lowest
mean density and lower taxa richness, but EPT taxa richness comparable to those seen in the run-
off streams. Drift densities were moderately high, but very diverse with high taxa richness,
especially with EPT taxa. Drift composition in the Oshetna River had the highest contributions
of mayflies and stoneflies compared to the other tributaries. Algal growth on substrates was low,
likely attributed to the higher turbidity from the glacial silt.
For the lakes, the July 2014 survey revealed that most invertebrate production was within the
euphotic zones. As might be expected, mean benthic densities and taxa richness from petite
Ponar grabs were much lower in deeper waters (profundal zone) compared to sites located in
shallow water that were within euphotic zone. D-net sweeps in the littoral zone along proximal
shorelines also revealed high taxa richness in those shallow areas, often including a number of
EPT taxa, which were not collected at profundal sites. Most invertebrate production in the three
lakes is likely attributed to zooplankton in the water column, with high mean areal densities and
biomass located in the mid-to-upper extent of Tyone Lake and the lower extent of Susitna Lake,
as well as within the deeper area of Lake Louise. Zooplankton was composed of mostly early-
instar copepods, with a smaller percentage of cladocerans. It is important, however, to note that
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zooplankton compositions in lake systems change over the course of the year, and that this study
intentionally provided a “snapshot in time.”
Measured water quality results from the River Productivity study were compared with other
measurements in the region and applicable standards to evaluate water quality conditions. The
water quality results from the tributary sites were compared with data from a study in the Tanana
River Basin (Moran 2007), as well as other studies summarizing the water quality in the Cook
Inlet Basin (Glass et al. 2004; Brabets et al. 1999). The Tanana River Basin study collected
water quality data on the mainstem and 59 tributaries of the Tanana River during water years
2004 through 2006. The Tanana River is a tributary of the Yukon River and flows laterally
along the northern slope of the Alaska Range. It is the major river basin located north of the
Susitna River basin. Comparisons for the tributaries are provided in Table 6.6-1.
In general, data collected at the tributary sites suggests water quality is high and productivity is
low. Most tributary sites had pH values close to neutral, except for the Tyone River site which
was more basic at 8.6 pH units. This value is outside the range of the water quality standard of
6.5-8.5. Kosina Creek and Devil Creek were slightly more acidic than the others with values
around 6.2 pH units. DO, conductivity, and temperature measurements are typical of healthy
water quality and are similar to other streams in the region. Only one temperature measurement,
16.8°C at Tyone River, exceeded the Alaska State water quality standard of 15°C for migr ation
and rearing areas and 13°C for spawning and egg and fry incubation (Table 6.6-1). However,
stream temperature varies widely depending on the season and time of day so it is reasonable to
assume the temperatures in the streams will vary significantly from what is reported in Table 5.8-
6.
Turbidity for the tributary sites is characteristically low (ie, < 10 NTU). Dissolved organic
carbon is also low and typical of other streams in the Cook Inlet, except for the Tyone River
which is on the higher side. Other nutrients measured including total phosphorus, ammonium,
and nitrate-nitrite are low when compared to other measurements in the region, suggesting these
tributary systems have low productivity.
Measured water quality results from the lake sites were compared with other measurements in
the region, applicable standards, and lake classifications to evaluate water quality conditions.
The water quality results from the lake sites were compared with data from a study of 50 lakes
within the Cook Inlet Basin (ADEC 2008). Comparisons for lakes are provided in Table 6.6-2.
In-situ measurements of pH, conductivity, DO, and temperature at the lake sites varied with
depth. Temperature measurements showed that the Susitna Lake (LSU) and Lake Louise (LLO)
become stratified while the Tyone Lake (LTY) site was fully mixed. Water quality
measurements for all three sites suggest the systems are oligotrophic, meaning they are nutrient
poor, have low productivity, and high transparency. The pH measurements decreased slightly on
the bottom. The lake water was fairly well oxygenated, but DO decreased to anoxic levels at the
RP-LSU-1 and RP-LSU-3 sites. Under anoxic conditions, sediments can release nutrients.
Nutrient concentrations and chlorophyll-a concentrations were low at all sites measured.
Nutrients were higher in the samples collected at the bottom depths; however, this may
correspond with nutrients being utilized in the photic region rather than any release from
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sediments. It should be noted that local residents indicated that Lake Louise had been turbid and
green only a few weeks before the sampling that occurred in July.
7. CONCLUSIONS
Implementation of the River Productivity Study (Study 9.8) during 2014 included:
1. completion of the analysis for data collected in 2013, as reported the ISR, Part A, Section
5 (AEA 2014a); the 2013 Initial River Productivity Results Technical Memorandum (R2
and UAF 2014b) filed on September 26, 2014; and this Study Implementation Report
(Section 5.1);
2. conducting field collections to both support and complete the invertebrate drift objective
(ISR Part A, Section 4.5; AE 2014), the trophic analysis objectives (ISR Part A, Section
4.6; AEA 2014a) and fish diet analysis objective (ISR Part A, Section 4.9; AEA 2014a)
with the stated variances; and
3. collection of supplemental information to characterize the pre-Project benthic
macroinvertebrate communities, with regard to species composition and abundance, and
algal production in selected Susitna River tributaries and lake systems located above
Devils Canyon (ISR Part C, Section 7.1.2.7.; AEA 2014a) as a proposed modification to
the Study Plan.
With the combined study efforts from 2013 to 2014, the River Productivity Study has
successfully collected baseline data to assist in evaluating the effects of Project-induced changes
in flow and the interrelated environmental factors (temperature, substrate, water quality) upon
the benthic macroinvertebrate and algal communities in the Middle and Lower Susitna River.
The study efforts to date have collected detailed spatial and seasonal baseline information on
benthic macroinvertebrates, periphyton, invertebrate drift, benthic and drift organic matter,
trophic relationships via growth modeling and stable isotope analysis, benthic macroinvertebrate
colonization dynamics, and benthic community resources in various upper basin tributaries and a
major lake system.
The combination of these 2013 and 2014 study efforts, including variances (ISR Part A, Section
4; AEA 2014a) and modifications (ISR Part C, Section 7.1; AEA 2014a), and the remainder of
the planned work in the next study year, which would also include these variances and the
integration with other studies, will fully achieve the proposed Study Plan objectives (ISR Part A,
Section 2; AEA 2014a).
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8. LITERATURE CITED
Alaska Department of Environmental Conservation (ADEC). 2008. 2008 Cook Inlet Basin
Lakes Survey Summary Report.
Alaska Energy Authority (AEA). 2012. Revised Study Plan: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/study-plan.
AEA. 2014a. Initial Study Report for the River Productivity Study (9.8): Susitna-Watana
Hydroelectric Project FERC Project No. 14241. June 2014. Prepared for the Federal
Energy Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/type/documents.
AEA. 2014b. Initial Study Report for the Salmon Escapement Study (9.7): Susitna-Watana
Hydroelectric Project FERC Project No. 14241. June 2014. Prepared for the Federal
Energy Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/type/documents.
Alaska Department of Fish and Game (ADF&G). 1983. Susitna Hydro Aquatic Studies Phase II
Basic Data Report: Resident and Juvenile Anadromous Fish Studies on the Susitna River
Below Devils Canyon, 1982. Alaska Department of Fish and Game, Anchorage, Alaska.
Armstrong, J.B. 2010. Comment on “Egg consumption in mature Pacific salmon
(Oncorhynchus spp.)” Appears in Canadian Journal of Fisheries and Aquatic Sciences
66(9): 1546–1553. Canadian Journal of Fisheries and Aquatic Sciences 67: 2052-2054.
Armstrong, J.B., D.E. Schindler, K.L. Omori, C.P. Ruff, and T.P. Quinn. 2010. Thermal
heterogeneity mediates the effects of pulsed subsidies across a landscape. Ecology 91:
1445-1454.
Ashton, H., D. Farkvam, and B. March. 1993. Fatty acid composition of lipids in the eggs and
alevins from wild and cultured Chinook Salmon (Oncorhynchus tshawytscha). Canadian
Journal of Fisheries and Aquatic Sciences 50: 648-655.Barbour, M.T., J. Gerritsen, B.D.
Snyder, and J.B. Stribling. 1999. Rapid bioassessment protocols for use in streams and
wadeable rivers: Periphyton, benthic macroinvertebrates and fish. Second Edition. EPA
841-B-99-002. U.S. Environmental Protection Agency; Office of Water; Washington
D.C.
Barbour, M.T., J. Gerritsen, B.D. Snyder, and J.B. Stribling. 1999. R apid bioassessment
protocols for use in streams and rivers: periphyton, benthic, macroinvertebrates, and fish.
Environmental Protection Agency, Washington D.C. EPA 841-B-99-002.
Barrick, L.G., B. Kepshire, and G. Cunningham. 1983. Upper Susitna River Salmon
Enhancement Study, Alaska Department of Fish and Game. Division of Fisheries
Rehabilitation Enhancement and Development. No. 4. 156 pp.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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Baxter, C.V., K.D. Fausch, & C.W. Saunders. 2005. Tangled webs: reciprocal flows of
invertebrate prey link streams and riparian zones. Freshwater Biology 50: 201- 220.
Beauchamp, D. 2009. Bioenergetic ontogeny: linking climate and mass-specific feeding to life-
cycle growth and survival of salmon. American Fisheries Society Symposium 70: 53–72.
Beauchamp, D.A., D.J. Stewart, and G.L. Thomas. 1989. Corroboration of a bioenergetics
model for sockeye salmon. Transactions of the American Fisheries Society 118: 597-607.
Brabets, T.P., G.L. Nelson, J.M. Dorava, and A.M. Milner. 1999. Water-Quality Assessment of
the Cook Inlet Basin, Alaska – Environmental Setting. U.S. Geological Survey Water-
Resources Investigations Report 99-4025.
Brey, T., C. Müller-Wiegmann, Z. Zittier, and W. Hagen. 2010. Body composition in aquatic
organisms—A global data bank of relationships between mass, elemental composition
and energy content. Journal of Sea Research 64: 334-340.
Bridcut, E.E. 2000. A study of terrestrial and aerial macroinvertebrates on river banks and their
contribution to drifting fauna and salmonid diets in a Scottish catchment. Hydrobiologia
427: 83-100.
Bunn, S.E., P.M. Davies, M. Winning. 2003. Sources of organic carbon supporting the food
web of an arid zone floodplain river. Freshwater Biology 48: 619–635.
Canton, S.P., and J.W. Chadwick. 1984. A new modified Hess sampler. Progressive Fish
Culturalist 46: 57-59.
Carlson R.E. and J. Simpson. 1996. A Coordinator's Guide to Volunteer Lake Monitoring
Methods. North American Lake Management Society. 96 pp.
Chipps, S. R. and J. E. Garvey. 2007. Quantitative assessment of food habits and feeding
patterns. Pages 473-514 in C. S. Guy and M. L. Brown, editors. Analysis and
Interpretation of Freshwater Fisheries Data. American Fisheries Society, Bethesda,
Maryland.
Cloe, W.W. and G.C. Garman. 1996. The energetic importance of terrestrial arthropod inputs to
three warm-water streams. Freshwater Biology 36: 104-114.
Cuffney, T.F., M.R. Meadow, S.D. Porter, and M.E. Kurtz. 1997. Distribution of fish, benthic
invertebrate, and algal communities in relation to physical and chemical conditions, Yakima
River basin, Washington, 1990. U.S. Geological Survey Water-Resources Investigations
Report 96-4280.
Cummins, K.W., R.W. Merritt, and M.B. Berg. 2008. Ecology and distribution of aquatic
insects. Pages 105-122 in R.W. Merritt, K.W. Cummins, and M.B. Berg editors. An
introduction to the aquatic insects of North America, 4th ed. Kendall/Hunt Publishing
Company, Dubuque, Iowa.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 75 October 2015
Davis, J.C. and G.A. Davis. 2008. Assessment and Classification of Matanuska-Susitna Fish
Habitat – Stream Water Temperature. Aquatic Restoration and Research Institute.
Deegan, L.A., H.E. Golden, C.J. Harvey, and B.J. Peterson. 1999. Influence of environmental
variability on the growth of age-0 and adult Arctic grayling. Transactions of the
American Fisheries Society 128: 1163-1175.
DeNiro, M.J. and S. Epstein. 1978. Influence of diet on the distribution of carbon isotopes in
animals. Geochimica et Cosmochimica Acta 42: 495-506.
DeVries, D.R., and R.V. Frie. 1996. Determination of age and growth. Pages 483–512 in B.R.
Murphy, and D.W. Willis, editors. Fisheries Techniques, 2nd edition. American
Fisheries Society, Bethesda, Maryland.
Dion, C.A. and N.F. Hughes. 2004. Testing the ability of a temperature-based model to predict
the growth of age-0 Arctic grayling. Transactions of the American Fisheries Society 133:
1047-1050.
Eaton, A., L. Clesceri, A. Greenberg. 1998. Standard Methods for the Examination of Water
and Wastewater. American Public Health Association, American Water Works
Association, Water Environment Federation, Washington, D.C.
Edmundson, J. A., V. P. Litchfield, G. L. Todd, J. M. Edmundson, and L. Brannian. 2000.
Central Region Limnology 2000 annual report of progress. Alaska Department of Fish
and Game, Commercial Fisheries Division, Regional Information Report No. 2A00- 27.
Federal Energy Regulatory Commission (FERC). 2013. Study Plan Determination on 14
remaining studies for the Susitna-Watana Hydroelectric Project. Issuance 20130401-
3022. Susitna-Watana Hydroelectric Project FERC No. P-14241. April 1, 2013.
http://elibrary.FERC.gov/idmws/file_list.asp?accession_num=20130401-3022.
Finlay, J.C. 2001. Stable-carbon-isotope ratios of river biota: implications for energy flow in
lotic food webs. Ecology 82: 1052–1064.
Finlay, J.C. 2004. Patterns and controls of lotic algal stable carbon isotope ratios. Limnology
and Oceanography 49: 850-861.
Finlay, J.C., and C. Kendall. 2007. Stable isotope tracing of temporal and spatial variability in
organic matter sources to freshwater ecosystems. Pages 283-333 in K. Lajtha and R.
Michener, editors. Stable Isotopes in Ecology and Environmental Science. Blackwell
Scientific, Oxford, U.K.
Finlay, J.C., M.E. Power, G. Cabana. 1999. Effects of water velocity on algal carbon isotope
ratios: implications for river food web studies. Limnography and Oceanography 44:
1198-1203.
Finlay, J.C., S. Khandwala, and M.E. Power. 2002. Spatial scales of carbon flow through a river
food web. Ecology 83: 1845-1859.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 76 October 2015
Fleming, I. A. and S. Ng. 1987. Evaluation of techniques for fixing, preserving, and measuring
salmon eggs. Canadian Journal of Fisheries and Aquatic Sciences 44: 1957-1962.
France R.L. and R.H. Peters. 1997. Ecosystem differences in the trophic enrichment of 13C in
aquatic foodwebs. Canadian Journal of Fisheries and Aquatic Sciences 54: 1255–1258.
France, R. and A. Cattaneo. 1998. 13C variability of benthic algae: effects of water colour via
modulation by stream current. Freshwtaer Biology 39: 617-622.
Gaedke, U., D. Straile, and C. Pahl-Wostl. 1996. Trophic structure and carbon flow dynamics in
the pelagic community of a large lake. – In: Polis, G.A. and K.O. Winemiller (ed), Food
webs: integration of patterns and dynamics. Chapman and Hall, 60-71.
Glass, R.L., T.P. Brabets, S.A. Frenzel, M.S. Whitman, and R.T Ourso. 2004. Water Quality in
the Cook Inlet Basin Alaska, 1998-2001. U.S. Geological Survey Circular 1240.
Gutierrez, L. 2011. Terrestrial invertebrate prey for juvenile Chinook Salmon: abundance and
environmental controls in an interior Alaskan river. M.S. Thesis, University of Alaska
Fairbanks.
Gregory, R.S. and T.G. Northcote. 1993. Surface, planktonic, and benthic foraging by juvenile
Chinook Salmon (Oncorhynchus tshawytscha) in turbid laboratory conditions. Canadian
Journal of Fisheries and Aquatic Sciences 50: 233-240.
Hadwen, W.L., M. Spears, M.J. Kennard. 2010. Temporal variability of benthic algal 13C
signatures influences assessments of carbon flows in stream food webs. Hydrobiologia
651: 239–251.
Hansen, T.F. and J.C. Richards. 1985. Availability of invertebrate food sources for rearing
juvenile Chinook Salmon in turbid Susitna River habitats. Susitna Hydro Aquatic
Studies, Report No. 8. Prepared for Alaska Power Authority. Alaska Department of Fish
and Game, Anchorage, Alaska. APA Document No. 2846.
Hanson, P.C., T.B. Johnson, D.E. Schindler, and J.F. Kitchell. 1997. Fish Bioenergetics 3.0.
University of Wisconsin Sea Grant Institute, Madison, Wisconsin.
Harvey, B.C. and S.F. Railsback. 2013. Feeding modes in stream salmonid population models:
is drift feeding the whole story? Environmental Biology of Fishes 97(5): 615-625.
Hubert, W.A. and H.A. Rhodes. 1989. Food selection by brook trout in a subalpine stream.
Hydrobiologia 178: 225-231.
Hughes, N. F. and L. M. Dill. 1990. Position choice by drift-feeding salmonids: model and test
for Arctic grayling (Thymallus arcticus) in subarctic mountain streams, interior Alaska.
Canadian Journal of Fisheries and Aquatic Sciences 47: 2039-2048.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 77 October 2015
Isely, J., and T. Grabowski. 2007. Age and Growth. Pages 187–228 in C.S. Guy, and M.L.
Brown, editors. Analysis and Interpretation of Freshwater Fisheries Data. American
Fisheries Society, Bethesda, Maryland.
Jardine, T.D., W.L. Hadwen, S.K. Hamilton, S. Hladyz, S.M. Mitrovic, K.A. Kidd, W.Y. Tsoi,
M. Spears, D.P. Westhorpe, V.M. Fry, F. Sheldon, and S.E. Bunn. 2014. Understanding
and overcoming baseline isotopic variability in running waters. River Research and
Applications 30: 155-165.
Junk, W.J., P.B. Bayley, R.E. Sparks. 1989. The flood pulse concept in river floodplain
systems. In: Dodge DP (ed) Proceedings of the international large rivers symposium.
Canadian Journal of Fisheries and Aquatic Sciences Special Publication 106: 89-109.
Klemm, D.J., J.M. Lazorchak, and D.V. Peck. 2000. Section 9. Benthic Macroinvertebrates in
J.M. Lazorchak, B.H. Hill, D.K. Averill, D.V. Peck, and D.J. Klemm, editors.
Environmental monitoring and assessment program – surface waters: Field operations
and methods for measuring the ecological condition of non-wadeable rivers and streams.
EPA/620/R-00/007, U.S. Environmental Protection Agency, Cincinnati, Ohio.
Klemm, D.J., P.A. Lewis, F. Fulk, and J.M. Lazorchak. 1990. Macroinvertebrate field and
laboratory methods for evaluating the biological integrity of surface waters. EPA/600/4-
90/030, Environmental Monitoring Systems Laboratory, U.S. Environmental Protection
Agency, Cincinnati, Ohio.
Kline T.C., J.J. Goering, O.A. Mathisen, A.L. Poe and P.L. Parker. 1990. Recycling of elements
transported by runs of Pacific salmon. I. 15N and 13C evidence in Sashin Creek,
southeastern Alaska. Canadian Journal of Fisheries and Aquatic Science 47: 136–144.
Koenings, J. P., J. A. Edmundson, G. B. Kyle, and J. M. Edmundson. 1987. Limnology field
and laboratory manual: Methods for assessing aquatic production. Alaska Department of
Fish and Game; Division of Fisheries Rehabilitation, Enhancement, and Development.
Number 71.
Koslucher, D.G. and G.W. Minshall. 1973. Food Habits of Some Benthic Invertebrates in a
Northern Cool-Desert Stream (Deep Creek, Curlew Valley, Idaho-Utah). Transactions of
the American Microscopical Society 92(3): 441-452.
Kutner, M.H., C.J. Nachtschiem, J. Neter, and W. Li. 2005. Applied Linear Statistical Models.
5th edition. McGraw-Hill Irwin, Boston.
Lazorchak, J. M., B. H. Hill, D. K. Averill, D. V. Peck, and D. J. Klemm (editors). 2000.
Environmental monitoring and assessment program – surface waters: field operations and
methods for measuring for measuring the ecological condition of non-wadeable rivers
and streams. EPA/620/R-00/007, U.S. Environmental Protection Agency, Cincinnati,
Ohio.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 78 October 2015
Lewis, W.M. Jr., S.K Hamilton, M.A. Rodriquez, F.J. Saunders III, and D.H. Lasi. 2001.
Foodweb analysis of the Orinoco floodplain based on production estimates and stable
isotope data. Journal of the North American Benthological Society 20: 241–254.
Major, E.B., and M.T. Barbour. 2001. Standard operating procedures for the Alaska Stream
Condition Index: A modification of the U.S. EPA rapid bioassessment protocols, 5th
edition. Prepared for the Alaska Department of Environmental Conservation, Anchorage,
Alaska.
McCarthy, S.G., J.J. Duda, J.M. Emlen, G.R. Hodgson, and D.A. Beauchamp. 2009. Linking
Habitat Quality with Trophic Performance of Steelhead along Forest Gradients in the
South Fork Trinity River Watershed, California. Transactions of the American Fisheries
Society 138(3):506-521.
McCutchan, J.H., W.M. Lewis, C. Kendall, and C.C. McGrath. 2003. Variation in trophic shift
for stable isotope ratios of carbon, nitrogen, and sulfur. Oikos 102: 378-390.
Meehan, W.R., and R.A. Miller. 1978. Stomach flushing: effectiveness and influence on
survival and condition of juvenile salmonids. Journal of the Fisheries Research Board of
Canada. 35(10): 1359-1363.
Merritt, R.W., K.W. Cummins, and M.B. Berg, editors. 2008. An Introduction to the Aquatic
Insects of North America, 4th edition. Kendall Hunt Publishing, Dubuque, IA.
Miller M.C., M. Kurzhals, A.E. Hershey and R.W. Merritt. 1998. Feeding behavior of black fly
larvae and retention of fine particulate organic matter in a high-gradient blackwater
stream. Canadian Journal of Fisheries and Aquatic Sciences 76: 228-235.
Moore J.W. and B.X. Semmens. 2008. Incorporating uncertainty and prior information into
stable isotope mixing models. Ecology Letters 11: 470-480.
Moore, J.W., D.E. Schindler, and C.P. Ruff. 2008. Habitat saturation drives thresholds in
stream subsidies. Ecology 89: 306-312.
Moran, E.H. 2007. Water quality in the Tanana River basin, Alaska, water years 2004-2006:
U.S. Geological Survey Open-File Report 2007-1390, 6p.
Moulton, S.R. II, J.G. Kennen, R.M. Goldstein, and J.A. Hambrook. 2002. Revised protocols
for sampling algal, invertebrate, and fish communities as part of the national water-
quality assessment program. USGS Open-File Report 02-150. U.S. Geological Survey,
Reston, Virginia.
Nakano, S. and M. Murakami. 2001. Reciprocal subsidies: dynamic interdependence between
terrestrial and aquatic food webs. Proceedings of the National Academy of Science 98:
166-170.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 79 October 2015
Nislow, K.H., C.L. Folt, and D.L. Parrish. 2000. Spatially explicit bioenergetic analysis of
habitat quality for age-0 Atlantic Salmon. Transactions of the American Fisheries Society
129: 1067-1081.
Oswood, M.W. 1989. Community structure of benthic invertebrates in interior Alaska (USA)
streams and rivers. Hydrobiologia 172: 97 -110.
Palmer, C., J. O'Keeffe, A. Palmer, T. Dunne and S. Radloff. 1993. Macroinvertebrate
functional feeding groups in the middle and lower reaches of the Buffalo River, Eastern
Cape, South Africa. I. Dietary variability. Freshwater Biology 29: 441-453.
Parnell, A.C., R. Inger, S. Bearhop, and A.L. Jackson. 2010. Source partitioning using stable
isotopes: coping with too much variation. PLoS One, 5(3), e9672.
Peck, D.V., A.T. Herlihy, B.H. Hill, R.M. Hughes, P.R. Kaufmann, D.J. Klemm, J.M.
Lazorchak, F.H. McCormick, S.A. Peterson, P.L. Ringold, T. Magee, and M. Cappaert.
2006. Environmental Monitoring and Assessment Program – Surface Waters Western
Pilot Study: Field Operations Manual for Wadeable Streams. EPA/620/R-06/003. U.S.
Environmental Protection Agency, Office of Research and Development, Washington,
D.C.
Perry, M. T. 2012. Growth of juvenile Chinook Salmon (Oncorhynchus tshawytscha) as an
indicator of density-dependence in the Chena River. Masters Thesis. University of Alaska
Fairbanks, Fairbanks, Alaska.
Piccolo, J.J., N.F. Hughes, and M.D. Bryant. 2008. Water velocity influences prey detection
and capture by drift-feeding juvenile Coho Salmon (Oncorhynchus kisutch) and steelhead
(Oncorhynchus mykiss irideus). Canadian Journal of Fisheries and Aquatic Sciences 65:
266-275.
Plumb, J.M. and C.M. Moffitt. 2015. Re-estimating temperature-dependent consumption
parameters in bioenergetics models for juvenile Chinook Salmon. Transactions of the
American Fisheries Society 144: 323-330.
Pohlert, T. 2014. The Pairwise Multiple Comparison of Mean Ranks Package (PMCMR). R
package.
Poole, G.C. 2002. Fluvial landscape ecology: addressing uniqueness within the river
discontinuum. Freshwater Biology 47: 641-660.
Post, D.M. 2002. Using stable isotopes to estimate trophic position: models, methods, and
assumptions. Ecology 83: 703–718.
R Core Team. 2015. R: A language and environment for statistical computing. R Foundation
for Statistical Computing, Vienna, Austria.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 80 October 2015
R2 Resource Consultants, Inc. (R2). 2013a. River Productivity Implementation Plan: Susitna-
Watana Hydroelectric Project FERC Project No. 14241. March 2013. Prepared for the
Alaska Energy Authority, Anchorage, Alaska. Available at: http://www.susitna-
watanahydro.org/wp-content/uploads/2013/03/Attachment-B.pdf
R2. 2013b. Technical Memorandum, Selection of Focus Areas and study sites in the Middle
Susitna River for instream flow and joint resource studies – 2013 and 2014. Prepared for
Alaska Energy Authority. March 1, 2013.
R2. 2013c. Technical Memorandum: Adjustments to Middle River Focus Areas. Prepared for
Alaska Energy Authority. May 30, 2013.
R2 Resource Consultants, Inc. (R2) and University of Alaska Fairbanks (UAF). 2014a.
Technical Memorandum: River Productivity Study (Study 9.8), 2014 Field Season River
Productivity Progress Report. September 26, 2014. Prepared for the Alaska Energy
Authority, Anchorage, Alaska. Available at: http://www.susitna-watanahydro.org/wp-
content/uploads/2014/09/9-08-RIVPRO-TM_2014_Spr.pdf
R2 and UAF. 2014b. Technical Memorandum: River Productivity Study (Study 9.8), 2013
Initial River Productivity Results. September 26, 2014. Prepared for the Alaska Energy
Authority, Anchorage, Alaska. Available at: http://www.susitna-watanahydro.org/wp-
content/uploads/2014/09/2013-Results_RivProTM_09172014.pdf
Rasmussen, J.B. 2010. Estimating terrestrial contribution to stream invertebrates and periphyton
using a gradient-based mixing model for δ13C. Journal of Animal Ecology 79: 393–402.
Rosen, R.A. 1981. Length-dry weight relationships of some freshwater zooplankton. Journal of
Freshwater Ecology 1: 225-229.
Scheuerell, M.D., J.W. Moore, D.E. Schindler, and C.J. Harvey. 2007. Varying effects of
anadromous sockeye salmon on the trophic ecology of two species of resident salmonids
in southwest Alaska. Freshwater Biology 52: 1944-1956.
Sedell, J.R., J.E. Richey, F.J. Swanson. 1989. The river continuum concept: a basis for the
expected ecosystem behavior of very large rivers? In: Dodge, D.P. (ed) Proceedings of
the international large rivers symposium. Canadian Journal of Fisheries and Aquatic
Sciences Special Publication 106: 49-55
Sotiropoulos, M.A., W.M. Tonn, and L.I. Wassenaar. 2004. Effects of lipid extraction on stable
carbon and nitrogen isotope analyses of fish tissues: potential consequences for food
webs studies. Ecology of Freshwater Fish 13: 155-160.
Stanford J.A., M.S. Lorang, and F.R. Hauer. 2005. The shifting habitat mosaic of river
ecosystems. Verhandlungen der International en Vereinigungfur Theoretischeund
Angewandte Limnologie 29: 123–136.
Stewart, D.J. and M. Ibarra. 1991. Predation and production by salmonine fishes in Lake
Michigan, 1978-88. Canadian Journal of Fisheries and Aquatic Sciences 48: 909-922.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 81 October 2015
Stock, B.C. and B.X. Semmens. 2013. MixSIAR GUI User Manual, version 1.0. Available at :
http://conserver.iugo-cafe.org/user/brice.semmens/MixSIAR
Thorp, J.H., M.D. Delong, K.S. Greenwood, A.F. Casper. 1998. Isotopic analysis of three food
web theories in constricted and floodplain regions of a large river. Oecologia 117: 551-
563.
Trudeau, V. and J.B. Rasmussen. 2003. The effect of water velocity on stable carbon and
nitrogen isotope signatures of periphyton, Limnology and Oceanography 48: 2194–2199.
Trueman, C.N., R.A.R. McGill, and P.H. Guyard. 2005. The effect of growth rate on tissue-diet
isotopic spacing in rapidly growing animals. An experimental study with Atlantic salmon
(Salmo salar). Rapid Communications in Mass Spectrometry 19: 3239-3247.
University of Alaska Fairbanks (UAF) and R2 Resource Consultants, Inc. (R2). 2014.
Technical Memorandum: River Productivity Study (Study 9.8), Fish Diet Sample Size
Sufficiency Analysis. December 17, 2014. Prepared for the Alaska Energy Authority,
Anchorage, Alaska. Available at: http://www.susitna-watanahydro.org/wp-
content/uploads/2014/12/9_08_RIVPRO_TM_DietSampleSizeSufficiency.pdf
URS and Tetra Tech. 2013. Quality Assurance Project Plan for Baseline Water Quality
Monitoring Sampling and Analysis Activities. Susitna-Watana Hydroelectric Project,
FERC No. P-14241. Prepared for Alaska Energy Authority, Anchorage, Alaska. 206 pp.
March 2013. http://www.susitna-watanahydro.org/wp-content/uploads/2013/03/Attachment-
D.pdf.
Vander Zanden, M.J. and J.B. Rasmussen. 2001. Variation in d15N and d13C trophic
fractionation: implications foraquatic food web studies. Limnology and Oceanography
46: 2061-2066.
Wetzel, R.G. 1983. Limnology, 2nd edn. Saunders, Philadelphia.
Wipfli, M.S. 1997. Terrestrial invertebrates as salmonid prey and nitrogen sources in streams:
contrasting old-growth and young-growth riparian forests in southeastern Alaska, USA.
Canadian Journal of Fisheries and Aquatic Sciences 54:1259–1269.
Wipfli, M.S. and C.V. Baxter. 2010. Linking ecosystems, food webs, and fish production:
subsidies in salmonid watersheds. Fisheries 35: 373 – 387.
Wurtsbaugh, W.A. and D. Neverman. 1988. Post-feeding thermotaxis and daily vertical
migration in a larval fish. Nature 333: 846-848.
Young, M.K., R.B. Rader, and T.A. Belish. 1997. Influence of macroinvertebrate drift and light
on the activity and movement of Colorado River Cutthroat Trout. Transactions of the
American Fisheries Society 126: 428-437.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 82 October 2015
Zah, R., P. Burgherr, S.M. Bernasconi, and U. Uehlinger. 2001. Stable isotope analysis of
marcoinvertebrates and their food sources in a glacier stream. Freshwater Biology 46:
871-882.
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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9. TABLES
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Table 4.2-1. Locations and descriptions of Focus Areas selected as sampling stations for the River Productivity study in the Lower and Middle River
Segments of the Susitna River in 2014. “X” indicates site established at that habitat type, “(x)” indicates no site established at that habitat type.
Focus
Area ID /
RivPro
ID 1
Common
Name
River
Productivity
Study Use Description
Geomorphic
Reach
Location
(PRM)
Area
Length
(mi)
Habitat Types Present
Additional
Sampling Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Beaver Complex Stable Isotopes Drift Above Tributary Upstream Downstream FA-184/
RP-184
Watana
Dam
Study Station
(3 sites)
Area approximately 1.4
miles downstream of
dam site
MR-1 185.7 184.7 1.0 X X X X X3
FA-173/
RP-173
Stephan
Lake,
Complex
Channel
Study Station
(5 sites)
Wide channel near
Stephan Lake with
complex of side
channels
MR-2 175.4 173.6 1.8 X X X X X X4
FA-141/
RP-141 Indian River Study Station
(4 sites)
Area covering Indian
River and upstream
channel complex
MR-6 143.4 141.8 1.6 X X X X2 (x) X X3
FA-104/
RP-104
Whiskers
Slough
Study Station
(5 sites)
Whiskers Slough
Complex MR-8 106.0 104.8 1.2 X X X X X X X4
RP-81 Montana
Creek Area
Study Station (4
sites)
Area nearby the mouth
of Montana Creek LR-2 82 81 1.0 X X X (x) X (x) X X3
Notes:
1 Focus Area identification numbers (e.g., Focus Area 184) represent the truncated Project River Mile (PRM) at the downstream end of each Focus Area.
2 Upland Slough located on Cook Inlet Regional Working Group (CIRWG) lands.
3 Drift samples taken at a new location upstream of Tributary Mouth macrohabitat
4 Drift samples used from an existing adjoining site upstream of Tributary Mouth macrohabitat.
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Table 4.2-2. Tributaries selected for sampling based on productivity estimates in Barrick et al. (1983).
Tributary Location Site ID Site Name
Location of Mouth
(PRM)
Approximate
Elevation (AMSL)
Upstream of Proposed
Reservoir
RP-BUT-1 Butte Creek 288.0 2,980
RP-TYO-1 Tyone River 247.3 2,369
RP-OSH-1 Oshetna River 235.1 2,991
Proposed Reservior
Inundation Zone
RP-JAY-1 Jay Creek 211.0 2,920
RP-KOS-1 Kosina Creek 209.1 3,060
RP-WAT-1 Watana Creek 196.9 2,991
RP-DED-1 Deadman Creek 189.4 2,966
Below Proposed Dam, above
Devils Canyon
RP-FOG-1 Fog Creek 179.3 3,125
RP-DEV-1* Devil Creek 164.8 1,586
* Site located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 4.3-1. Adult emergence traps deployment locations with install and removal dates, and count of
number of collection visits with the number of successful samples collected in 2013.
Station Site
Install
Date
Removal
Date
Number of
Collection
Visits
Number of
Samples
Collected
RP- 81 RP-81-1 7/1/2013 10/1/2013 4 3
(Montana Creek) RP-81-2 6/30/2013 10/1/2013 4 1
RP-81-3 6/29/2013 10/3/2013 4 4
RP-81-4 6/30/2013 10/3/2013 4 3
FA-104 RP-104-1 6/23/2013 9/27/2013 4 4
(Whiskers Slough) RP-104-2 6/19/2013 9/27/2013 4 3
RP-104-3 6/21/2013 9/30/2013 4 4
RP-104-4 6/23/2013 9/28/2013 4 4
RP-104-5 6/21/2013 9/28/2013 4 2
FA-141 RP-141-1 6/25/2013 9/25/2013 4 2
(Indian River) RP-141-2 6/25/2013 9/26/2013 3 2
RP-141-3 6/27/2013 9/25/2013 3 1
RP-141-4 6/27/2013 9/26/2013 3 1
FA-173 RP-173-1 7/11/2013 9/23/2013 2 2
(Stephan Lake Complex) RP-173-2 7/29/2013 9/23/2013 2 2
RP-173-3 7/11/2013 9/23/2013 2 1
RP-173-4 7/10/2013 9/24/2013 4 3
FA-184 RP-184-1 7/13/2013 9/22/2013 3 2
(Watana Dam) RP-184-3 7/12/2013 9/22/2013 3 3
Totals 65 47
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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Table 4.3-2. Adult emergence trap deployment locations with 2013 collection period dates, durations,
estimated densities for successfully retrieved samples, and description of the trap condition upon collection.
Sampling
Site Habitat
Time Period Duration
(days)
Density
(per sq
m)
Density
(per sq m)
per day Trap Condition
Deployment
Date
Collection
Date
RP-184-1 Tributary
Mouth
7/13/2013 7/29/2013 16 413.9 25.9 Out of Water, sample retained*
7/29/2013 8/21/2013 23 — — No sample collected; submerged,
bottle filled with sediment/water
8/21/2013 9/22/2013 32 102.8 3.2 Out of Water, sample retained*
RP-184-2 Side
Channel
7/12/2013 7/29/2013 17 — — No trap installed
7/29/2013 8/21/2013 23 — — No trap installed
8/21/2013 9/22/2013 32 — — No trap installed
RP-184-3 Main
Channel
7/12/2013 7/29/2013 17 4,066.7 239.2 Out of Water, sample retained*
7/29/2013 8/21/2013 23 725.0 31.5 Sample collected
8/21/2013 9/22/2013 32 188.9 5.9 Out of Water, sample retained*
RP-173-1 Tributary
Mouth
7/11/2013 7/29/2013 18 466.7 25.9 Out of Water, sample retained*
7/29/2013 8/31/2013 33 — — No replacement trap available
8/31/2013 9/23/2013 23 83.3 3.6 Out of Water, sample retained*
RP-173-2 Main
Channel
7/9/2013 7/29/2013 20 — — No trap installed
7/29/2013 8/19/2013 21 875.0 41.7 Sample collected
8/20/2013 9/23/2013 34 250.0 7.4 Out of Water, sample retained*
RP-173-3 Side
Channel
7/11/2013 7/29/2013 18 — — No sample collected, damaged
7/29/2013 8/31/2013 33 — — No replacement trap available
8/31/2013 9/23/2013 23 122.2 5.3 Out of Water, sample retained*
RP-173-4 Side
Slough
7/10/2013 7/28/2013 18 130.6 7.3 Sample collected
7/28/2013 8/19/2013 22 494.4 22.5 Sample collected
8/19/2013 8/31/2013 12 386.1 32.2 Out of Water, sample retained*
8/31/2013 9/24/2013 24 — — No sample collected, damaged
RP-141-1 Tributary
Mouth
6/25/2013 7/30/2013 35 4,055.6 115.9 Sample collected
7/30/2013 8/7/2013 8 2,318.5 289.8 Sample collected
8/7/2013 8/17/2013 10 — — No sample collected, Lost
8/17/2013 9/25/2013 39 — — No sample collected; bottle filled
with river water
RP-141-2 Side
Channel
6/25/2013 7/30/2013 35 441.7 12.6 Sample collected
7/30/2013 8/18/2013 19 647.2 34.1 Sample collected
8/18/2013 9/26/2013 39 — — No sample collected; bottle filled
with sediment
RP-141-3
Mult Split
Main
Channel
6/27/2013 7/30/2013 33 — — No sample collected, Lost
7/30/2013 8/17/2013 18 183.3 10.2 Out of Water, sample retained*
8/17/2013 9/25/2013 39 — — No sample collected; stranded,
bottle full of sediment
RP-141-4 Upland
Slough
6/27/2013 7/30/2013 33 1,772.2 53.7 Sample collected
7/30/2013 8/18/2013 19 — — No sample collected, damaged
8/18/2013 9/26/2013 39 — — No sample collected, damaged
* Trap was damaged and/or stranded out of water during sampling period but sample was intact; sampling duration
unknown. Estimates are calculated assuming full sampling duration.
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Table 4.3-2 (cont.) Adult emergence trap deployment locations with 2013 collection period dates, durations, estimated
densities for successfully retrieved samples, and description of the trap condition upon collection.
Sampling
Site Habitat
Time Period Duration
(days)
Density
(per sq
m)
Density
(per sq m)
per day Sample Condition
Deployment
Date
Collection
Date
RP-104-1
Tributary
Mouth/
Side
Slough
6/23/2013 8/1/2013 39 450.0 11.5 Damaged, sample retained*
8/1/2013 8/12/2013 11 488.9 44.4 Sample collected
8/12/2013 8/30/2013 18 683.3 38.0 Sample collected
8/30/2013 9/27/2013 28 202.8 7.2 Sample collected
RP-104-2 Side
Slough
6/19/2013 8/1/2013 43 1,286.1 29.9 Damaged, sample retained*
8/1/2013 8/12/2013 11 41.7 3.8 Damaged, sample retained*
8/12/2013 9/1/2013 20 — — No sample collected; bottle filled
with sediment
9/1/2013 9/27/2013 26 188.9 7.3 Sample collected
RP-104-3 Main
Channel
6/21/2013 8/1/2013 41 47.2 1.2 Out of Water, sample retained*
8/1/2013 8/13/2013 12 47.2 3.9 Out of Water, sample retained*
8/13/2013 9/1/2013 19 316.7 16.7 Out of Water, sample retained*
9/1/2013 9/30/2013 29 50.0 1.7 Out of Water, sample retained*
RP-104-4 Upland
Slough
6/23/2013 8/1/2013 39 2,463.9 63.2 Sample collected
8/1/2013 8/16/2013 15 2,548.1 169.9 Sample collected
8/16/2013 9/1/2013 16 1,786.1 111.6 Sample collected
9/1/2013 9/28/2013 27 86.1 3.2 Sample collected
RP-104-5 Side
Channel
6/21/2013 8/1/2013 41 22.2 0.5 Sample collected
8/1/2013 8/13/2013 12 22.2 1.9 Sample collected
8/16/2013 9/1/2013 16 — — No sample collected; bottle filled
with sediment
9/1/2013 9/28/2013 27 — — No sample collected; bottle filled
with sediment
RP-81-1 Upland
Slough
7/1/2013 8/2/2013 32 1,350.0 42.2 Sample collected
8/2/2013 8/14/2013 12 538.9 44.9 Partially Out of Water, sample
retained*
8/14/2013 9/1/2013 18 569.4 31.6 Out of Water, sample retained*
9/1/2013 10/1/2013 30 — — No sample collected, damaged
RP-81-2 Tributary
Mouth
6/30/2013 8/2/2013 33 — — No sample collected, submerged
8/2/2013 8/15/2013 13 166.7 12.8 Sample collected
8/15/2013 9/1/2013 17 — — No sample collected, Lost
9/1/2013 10/1/2013 30 — — No sample collected, stranded
RP-81-3
Split
Main
Channel
6/29/2013 8/2/2013 34 788.9 23.2 Sample collected
8/2/2013 8/14/2013 12 366.7 30.6 Sample collected
8/14/2013 9/1/2013 18 169.4 9.4 Sample collected
9/1/2013 10/3/2013 32 58.3 1.8 Out of Water, damaged, sample
retained*
RP-81-4 Side
Channel
6/30/2013 8/2/2013 33 411.1 12.5 Sample collected
8/2/2013 8/15/2013 13 322.2 24.8 Sample collected
8/15/2013 9/1/2013 17 116.7 6.9 Sample collected
9/1/2013 10/3/2013 32 — — No sample collected, damaged
* Trap was damaged and/or stranded out of water during sampling period but sample was intact; sampling duration
unknown. Estimates are calculated assuming full sampling duration.
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Table 4.4-1. Sampling Stations and Seasonal Sampling Event dates of collection for the River Productivity
study in the Lower and Middle River Segments of the Susitna River, 2014.
Seasonal Sampling Event
Station Spring 2014 Summer 2014 Fall 2014
FA-184 (Watana Dam) 6/17 – 6/18 8/13 – 8/14 9/29 – 9/30
FA-173 (Stephan Lake Complex) 6/18 – 6/19 8/11 – 8/12 9/27 – 9/28
FA-141 (Indian River) 6/15 – 6/16 8/9 – 8/10 9/25 – 9/26
FA-104(Whiskers Slough) 6/10 – 6/12 8/4 – 8/6 9/22 – 9/24
RP-81 (Montana Creek) 6/13 – 6/14 8/7 – 8/8 9/20 – 9/21
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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Table 4.4-2. Benthic drift and plankton tow sample totals for 2014 sampling during three sampling events
(Spr= Spring, Sum=Summer, Fall) for sampling sites in the Middle and Lower River Segments of the Susitna
River, for the River Productivity Study (9.8).
Site
Macrohabitat
Type
Drift Samples Plankton Tow Samples
Spr Sum Fall Total Spr Sum Fall Total
RP-184-1 Tributary Mouth 2 2 2 6
RP-184-2 Side Channel 2 2 2 6
RP-184-3 Main Channel 2 2 2 6
RP-184-4* Main Channel 2 2 2 6
RP-173-1 Tributary Mouth 2 2 2 6
RP-173-2 Main Channel 2 2 2 6
RP-173-3* Side Channel 2 2
4
5 5
RP-173-4 Side Slough
5 5 5 15
RP-173-51 Upland Slough 2 2
4
5 5
RP-141-1 Tributary Mouth 2 2 2 6
RP-141-2 Side Channel 2 2
4
5 5
RP-141-3 Mult Split Main Channel 2 2 2 6
RP-141-4 Upland Slough
5 5 5 15
RP-141-5* Main Channel 2 2 2 6
RP-104-1 Tributary Mouth 2
2 4
5
5
RP-104-2 Side Slough
5 5 5 15
RP-104-2.1* Side Slough (above tributary mouth)
5 5
10
RP-104-3 Main Channel 2 2 2 6
RP-104-4 Upland Slough 2
2 5 5 5 15
RP-104-5 Side Channel 2 2 2 6
RP-81-1 Upland Slough
5 5 5 15
RP-81-2 Tributary Mouth 2 2 2 6
RP-81-3 Split Main Channel 2 2 2 6
RP-81-4 Side Channel 2 2 2 6
RP-81-5* Side Channel 2 2 2 6
Totals 40 36 32 108 30 35 40 105
* Drift samples collected for above tributary comparisons.
1 Upland Slough located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 4.6-1. Itemized listing of sample components collected and analyzed in 2014 for Stable Isotope Analysis
from the four sampling stations (16 sites total) in the Middle and Lower River Segments of the Susitna River
for the River Productivity Study.
Category Component Spring 2014 Summer 2014 Fall 2014
Total Number
Analyzed (2014)
Endmembers
Benthic algae 48 46 48 142
Organic matter - drift 32 32 32 96
Organic matter - benthic 48 48 48 144
Salmon carcass 0 4 5 9
Salmon eggs 0 0 0 0
Subtotal 128 130 133 391
Invertebrates
Benthic - collectors 76 77 75 228
Benthic - grazers 26 38 19 83
Benthic - predators 55 55 58 168
Benthic - shredders 37 33 40 110
Emergents 29 20 12 61
Terrestrial 27 28 16 71
Subtotal 250 251 220 721
Fish
Rainbow trout - juveniles 0 5 3 8
Rainbow trout - adults 8 2 1 11
Chinook Salmon - juveniles 39 75 64 178
Coho Salmon - juveniles 52 42 40 134
Arctic grayling - juveniles 24 37 24 85
Arctic grayling - adults 6 16 7 29
Subtotal 129 177 139 445
2014 Totals 507 558 492 1557
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Table 4.7-1. Number of fish collected for fish gut content, scales, and stable isotope tissue samples during the 2014 Spring Sampling event for each
target species / age class from each sampling site in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Station Sampling
site Habitat Type
Chinook
Salmon -
small
Coho Salmon
- small
Rainbow
Trout - small
Rainbow
Trout - large
Arctic
Grayling -
small
Arctic
Grayling -
large Totals
2014 Spring Totals
FA-184
(Watana Dam)
RP-184-1 Tributary Mouth 0 0 0 0 0 1 1
RP-184-2 Side Channel 3 0 0 0 7 0 10
RP-184-3 Main Channel 0 0 0 0 1 0 1
FA-173
(Stephan Lake
Complex)
RP-173-1 Tributary Mouth 0 0 0 0 1 3 4
RP-173-2 Main Channel 1 0 0 0 5 2 8
RP-173-3 Side Channel 0 0 0 0 0 0 0
RP-173-4 Side Slough 0 0 0 0 0 0 0
RP-173-5* Upland Slough 0 0 0 0 0 0 0
FA-141
(Indian River)
RP-141-1 Tributary Mouth 0 8 0 6 0 1 15
RP-141-2 Side Channel 4 1 0 0 0 0 5
RP-141-3 Mult Split Main Channel 8 0 0 0 2 3 13
RP-141-4 Upland Slough 1 0 0 2 0 0 3
FA-104
(Whiskers Slough)
RP-104-1 Side Slough 7 9 0 0 0 0 16
RP-104-2 Side Slough 0 6 0 0 0 0 6
RP-104-3 Main Channel 2 0 0 0 2 0 4
RP-104-4 Upland Slough 0 8 0 0 0 0 8
RP-104-5 Side Channel 0 2 0 0 0 0 2
RP- 81
(Montana Creek)
RP-81-1 Upland Slough 1 8 0 0 0 0 9
RP-81-2 Tributary Mouth 0 6 0 0 0 0 6
RP-81-3 Split Main Channel 5 5 0 0 0 0 10
RP-81-4 Side Channel 4 2 0 0 2 0 8
Spring Totals 36 55 0 8 20 10 129
* Upland Slough located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 4.7-2. Number of fish collected for fish gut content, scales, and stable isotope tissue samples during the 2014 Summer Sampling event for each
target species / age class from each sampling site in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Station Sampling
site Habitat Type
Chinook
Salmon -
small
Coho Salmon
- small
Rainbow
Trout - small
Rainbow
Trout - large
Arctic
Grayling -
small
Arctic
Grayling -
large Totals
2014 Summer Totals
FA-184
(Watana Dam)
RP-184-1 Tributary Mouth 0 0 0 0 3 6 9
RP-184-2 Side Channel 0 0 0 0 2 3 5
RP-184-3 Main Channel 0 0 0 0 1 5 6
FA-173
(Stephan Lake
Complex)
RP-173-1 Tributary Mouth 0 0 0 0 0 14 14
RP-173-2 Main Channel 0 0 0 0 0 6 6
RP-173-3 Side Channel 0 0 0 0 0 0 0
RP-173-4 Side Slough 0 0 0 0 7 0 8
RP-173-5* Upland Slough 0 0 0 0 0 0 0
FA-141
(Indian River)
RP-141-1 Tributary Mouth 8 0 0 3 0 0 11
RP-141-2 Side Channel 8 0 0 0 0 0 8
RP-141-3 Mult Split Main Channel 8 0 0 0 0 0 8
RP-141-4 Upland Slough 5 0 0 0 0 1 6
FA-104
(Whiskers Slough)
RP-104-1 Tributary Mouth 2 6 0 2 0 0 10
RP-104-2 Side Slough 3 5 0 0 0 0 8
RP-104-3 Main Channel 8 2 0 0 1 1 12
RP-104-4 Upland Slough 6 8 0 0 0 0 14
RP-104-5 Side Channel 8 5 0 0 0 1 14
RP- 81
(Montana Creek)
RP-81-1 Upland Slough 4 8 0 0 0 0 12
RP-81-2 Tributary Mouth 7 7 0 1 0 1 16
RP-81-3 Split Main Channel 8 0 0 0 0 0 8
RP-81-4 Side Channel 3 0 0 0 1 0 4
Summer Totals 78 41 0 6 15 38 179
* Upland Slough located on Cook Inlet Region Working Group (CIRWG) lands.
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Table 4.7-3. Number of fish collected for fish gut content, scales, and stable isotope tissue samples during the 2014 Fall Sampling event for each target
species / age class from each sampling site in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Station Sampling
site Habitat Type
Chinook
Salmon -
small
Coho Salmon
- small
Rainbow
Trout - small
Rainbow
Trout - large
Arctic
Grayling -
small
Arctic
Grayling -
large Totals
2014 Fall Totals
FA-184
(Watana Dam)
RP-184-1 Tributary Mouth 0 0 0 0 1 5 6
RP-184-2 Side Channel 0 0 0 0 1 0 1
RP-184-3 Main Channel 0 0 0 0 2 0 2
FA-173
(Stephan Lake
Complex)
RP-173-1 Tributary Mouth 0 0 0 0 0 0 0
RP-173-2 Main Channel 0 0 0 0 0 2 2
RP-173-3 Side Channel 0 0 0 0 4 0 4
RP-173-4 Side Slough 0 0 0 0 1 0 8
RP-173-5* Upland Slough 0 0 0 0 0 0 0
FA-141
(Indian River)
RP-141-1 Tributary Mouth 6 1 1 1 0 0 9
RP-141-2 Side Channel 8 0 0 0 0 0 8
RP-141-3 Mult Split Main Channel 8 0 0 0 0 1 9
RP-141-4 Upland Slough 3 0 0 0 0 0 3
FA-104
(Whiskers Slough)
RP-104-1 Tributary Mouth 7 9 1 0 1 0 18
RP-104-2 Side Slough 0 10 0 0 0 0 10
RP-104-3 Main Channel 4 0 0 0 6 3 13
RP-104-4 Upland Slough 1 8 0 0 0 0 9
RP-104-5 Side Channel 7 6 0 0 3 1 17
RP- 81
(Montana Creek)
RP-81-1 Upland Slough 0 13 1 0 0 0 14
RP-81-2 Tributary Mouth 0 2 0 0 0 0 2
RP-81-3 Split Main Channel 6 0 0 0 0 0 6
RP-81-4 Side Channel 7 0 0 0 0 0 7
Fall Totals 57 49 3 1 19 12 141
* Upland Slough located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 4.8-1. Total number of Benthic and Drift Samples with organic matter components collected for 2013 sampling during three sampling ev ents
(Spr=Spring, Sum=Summer, Fall) and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for the River
Productivity Study.
Site Macrohabitat Type
Hess Samples Ponar Grab Samples Drift Samples
Spr Sum Fall
Post-
Storm Total Spr Sum Fall
Post-
Storm Total Spr Sum Fall
Total
RP-184-1 Tributary Mouth 5 5 5
15
2 2 2 6
RP-184-2 Side Channel 5 5 5
15
2 2 2 6
RP-184-3 Main Channel 5 5 5
15
2 2 2 6
RP-173-1 Tributary Mouth 5 5 5
15
2 2 2 6
RP-173-2 Main Channel 5 5 5
15
2 2 2 6
RP-173-3 Side Channel 5 5 5
15
2 2 2
RP-173-4 Side Slough 5 5 2 5 17 5 5 5 5 20
RP-141-1 Tributary Mouth 5 5 5
15
2 2 2 6
RP-141-2 Side Channel 5 5
10
5
5 2 2 2 6
RP-141-3
Mult Split Main
Channel 5 5 5
15
2 2 2
RP-141-4 Upland Slough 5 4 3
12 5 5 5
15
RP-141-5* Main Channel
2 2
RP-104-1
Trib Mouth/Side
Slough 5 5 5
15
2 2 2 6
RP-104-2 Side Slough 5 5 2 5 17
5
5 2 2
RP-104-3 Main Channel 5 5 5
15
2 2 2 6
RP-104-4 Upland Slough
5 5 5
15 2 2
RP-104-5 Side Channel 5 5 5
15
2 2 2
RP-81-1 Upland Slough
5
5 5 5
10 2 2
RP-81-2 Tributary Mouth 5 5 5
15
2 2 2 6
RP-81-3 Split Main Channel 5 5 5
15
2 2 2 6
RP-81-4 Side Channel 5 5 5
15
2 2 2 6
RP-81-5* Side Channel
2 2 2 6
Totals 90 89 82 10 271 20 20 25 5 70 36 34 28 92
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Table 4.10-1. Macroinvertebrate and algae sample totals for July 2014 sampling at nine selected tributaries
in the Middle and Upper River Segments of the Susitna River for the River Productivity Study.
Tributary Location Site ID Site Name
Elevation
(AMSL)
Date
Sampled
Hess
Samples
Drift
Samples
Algae
Samples
Upstream of
Proposed
Reservoir
RP-BUT-1 Butte Creek 2,980 20140716 5 2 5
RP-TYO-1 Tyone River 2,369 20140714 5 2 5
RP-OSH-1 Oshetna River 2,991 20140714 5 2 5
Proposed
Reservior
Inundation Zone
RP-JAY-1 Jay Creek 2,920 20140717 5 2 5
RP-KOS-1 Kosina Creek 3,060 20140715 5 2 5
RP-WAT-1 Watana Creek 2,991 20140717 5 2 5
RP-DED-1 Deadman Creek 2,966 20140716 5 2 5
Below Proposed
Dam, above Devils
Canyon
RP-FOG-1 Fog Creek 3,125 20140715 5 2 5
RP-DEV-1* Devil Creek 1,586 20140718 5 2 5
Totals 45 18 45
* Site located on Cook Inlet Regional Working Group (CIRWG) lands.
Table 4.10-2. Benthic macroinvertebrate and plankton tow sample totals for July 2014 sampling at nine sites
within three lakes located in the Upper River basin of the Susitna River for the River Productivity Study.
Site ID Site Name
Depth
(ft)
Date
Sampled
Ponar
Samples
Plankton
Tow
Samples
Shoreline
Sweeps
Water Quality Grabs
(at surface,
euphotic, and
bottom depths)
RP-LTY-1 Tyone Lake - Lower 4.5 20140722 5 5 1 1
(at 2 ft)
RP-LTY-2 Tyone Lake - Middle 16.5 20140722 5 5 1 2
(at 2 ft and 15 ft)
RP-LTY-3 Tyone Lake - Upper 21 20140722 5 5 1 2
(at 2 ft and 18 ft)
RP-LSU-1 Susitna Lake - Lower 78 20140723 5 5 1 3
(at 6, 36, and 75 ft)
RP-LSU-2 Susitna Lake - Middle 22 20140723 5 5 1 2
(at 2 ft and 20 ft)
RP-LSU-3 Susitna Lake - Upper 90 20140723 5 5 1 3
(at 6, 36, and 87 ft)
RP-LLO-1 Lake Louise - Lower 107 20140724 5 5 1 3
(at 6, 33, and 95 ft)
RP-LLO-2 Lake Louise - Middle 133 20140721 5 5 1 3
(at 6, 42, and 129 ft)
RP-LLO-3 Lake Louise - Upper 17 20140724 5 5 1 2
(at 2 ft and 16 ft)
Totals 45 45 9 21
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Table 4.10-3. Water quality sample parameters taken for July 2014 sampling at nine selected tributaries and
nine lake sites in the Middle and Upper River Segments of the Susitna River for the River Productivity Study.
Analyses Method Sites Container Preservative Standard Holding Time
Alkalinity SM21
2320B Lake
500-ml high-
density
polyethylene
(HDPE)
Cool to 0-6°C 14 days
Nitrate+Nitrite SM18 4500
NO3-F Tributary, Lake
500-ml HDPE
Freeze 28 days
Ammonia as N SM18
4500NH3-H Tributary, Lake Freeze 28 days
Soluble Reactive
Phosphorous
(SRP)
SM18
4500PF Tributary, Lake Freeze (field filter) 48 hours filtered*
Total Kjeldahl
Nitrogen (TKN) EPA 351.1 Tributary, Lake
250-ml HDPE
Freeze 28 days
Total Phosphorus
(TP)
SM18
4500PF Tributary, Lake Freeze (field filter) 28 days
Chlorophyll-a SM 10200H Tributary, Lake 500-ml HDPE
Field filter, protect
from light, freeze
filter to -4°C
21 days
Dissolved organic
carbon (DOC)
SM21
5310B Tributary, Lake 125-ml Amber
Glass
Hydrochloric acid
(HCL) (pH<2)
Cool to 0-6°C
(field filter before
preservation)
28 days
* Communication with the analytical lab indicated that freezing the SRP sample would allow for up to 28 days
holding time; maximum holding time was 22 days or less.
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Table 5.1-1. Values of density, taxonomic richness, and relative abundance by habitat from adult emergence trap samples collected in 2013 during the
open water season for sites within the Watana Dam Focus area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity
Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Density (per
sq m) per
day
Taxa
Richness EPT Taxa Mayfly (E)
Taxa
Stonefly (P)
Taxa
Caddisfly
(T) Taxa
Percent
Aquatic
Taxa
Percent
Terrestrial
Taxa
Percent
Undeter-
mined
RP-184-1 Tributary
Mouth
7/13/2013 7/29/2013 25.9 28 6 2 1 3 70.5 29.5 0
7/29/2013 8/21/2013 — — — — — — — — —
8/21/2013 9/22/2013 3.2 10 0 0 0 0 70.3 29.7 0
RP-184-2 Side
Channel
7/12/2013 7/29/2013 — — — — — — — — —
7/29/2013 8/21/2013 — — — — — — — — —
8/21/2013 9/22/2013 — — — — — — — — —
RP-184-3 Main
Channel
7/12/2013 7/29/2013 239.2 16 1 0 0 1 50.5 49.5 0
7/29/2013 8/21/2013 31.5 28 5 1 3 1 79.3 20.7 0
8/21/2013 9/22/2013 5.9 14 4 1 2 1 86.8 13.2 0
Table 5.1-2. Taxonomic composition metric values from adult emergence trap samples collected in 2013 during the open water season for sites within
the Watana Dam Focus area (FA-184) in the Middle River Segment of the Susitna River for the River Productivity Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent
Coleo-
ptera
Percent
Chiro-
nomids
Percent
Other
Diptera
Percent
Hymeno-
ptera
Percent
Hemiptera
Percent
Others
RP-184-1 Tributary
Mouth
7/13/2013 7/29/2013 1.3 2.7 2.7 2.0 29.5 57.7 1.3 1.3 1.3
7/29/2013 8/21/2013 — — — — — — — — —
8/21/2013 9/22/2013 0.0 0.0 0.0 0.0 56.8 35.1 2.7 0.0 5.4
RP-184-2 Side
Channel
7/12/2013 7/29/2013 — — — — — — — — —
7/29/2013 8/21/2013 — — — — — — — — —
8/21/2013 9/22/2013 — — — — — — — — —
RP-184-3 Main
Channel
7/12/2013 7/29/2013 0.0 0.0 0.3 0.0 44.3 8.7 0.3 45.9 0.5
7/29/2013 8/21/2013 0.8 44.1 1.1 2.3 29.1 11.1 3.1 3.4 5.0
8/21/2013 9/22/2013 4.4 5.9 1.5 0.0 69.1 16.2 1.5 1.5 0.0
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FERC Project No. 14241 Page 99 November 2015
Table 5.1-3. Values of density, taxonomic richness, and relative abundance by habitat from adult emergence trap samples collected in 2013 during the
open water season for sites within the Stephan Lake Complex Focus area (FA-173) in the Middle River Segment of the Susitna River for the River
Productivity Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Density
(per sq m)
per day
Taxa
Richness EPT Taxa Mayfly (E)
Taxa
Stonefly (P)
Taxa
Caddisfly
(T) Taxa
Percent
Aquatic
Taxa
Percent
Terrestrial
Taxa
Percent
Undeter-
mined
RP-173-1 Tributary
Mouth
7/11/2013 7/29/2013 25.9 21 0 0 0 0 35.7 64.3 0
7/29/2013 8/31/2013 — — — — — — — — —
8/31/2013 9/23/2013 3.6 3 1 1 0 0 96.7 3.3 0
RP-173-2 Main
Channel
7/9/2013 7/29/2013 — — — — — — — — —
7/29/2013 8/19/2013 41.7 19 3 1 2 0 93.0 7.0 0
8/20/2013 9/23/2013 7.4 16 3 1 2 0 86.7 13.3 0
RP-173-3 Side
Channel
7/11/2013 7/29/2013 — — — — — — — — —
7/29/2013 8/31/2013 — — — — — — — — —
8/31/2013 9/23/2013 5.3 6 1 1 0 0 88.6 11.4 0
RP-173-4 Side
Slough
7/10/2013 7/28/2013 7.3 10 2 2 0 0 83.0 17.0 0
7/28/2013 8/19/2013 22.5 3 1 1 0 0 93.8 6.2 0
8/19/2013 8/31/2013 32.2 26 3 1 1 1 50.4 49.6 0
8/31/2013 9/24/2013 — — — — — — — — —
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Table 5.1-4. Taxonomic composition metric values from adult emergence trap samples collected in 2013 during the open water season for sites within
the Stephan Lake Complex Focus area (FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent
Coleoptera
Percent
Chironomids
Percent
Other
Diptera
Percent
Hymeno-
ptera
Percent
Hemiptera
Percent
Others
RP-173-1 Tributary
Mouth
7/11/2013 7/29/2013 0.0 0.0 0.0 6.0 26.2 49.4 2.4 13.7 2.4
7/29/2013 8/31/2013 — — — — — — — — —
8/31/2013 9/23/2013 3.3 0.0 0.0 0.0 93.3 0.0 0.0 0.0 3.3
RP-173-2 Main
Channel
7/9/2013 7/29/2013 — — — — — — — — —
7/29/2013 8/19/2013 0.3 30.2 0.0 0.6 54.3 11.1 0.3 1.0 2.2
8/20/2013 9/23/2013 5.6 21.1 0.0 1.1 51.1 15.6 1.1 0.0 4.4
RP-173-3 Side
Channel
7/11/2013 7/29/2013 — — — — — — — — —
7/29/2013 8/31/2013 — — — — — — — — —
8/31/2013 9/23/2013 59.1 0.0 0.0 0.0 29.5 6.8 2.3 0.0 2.3
RP-173-4 Side
Slough
7/10/2013 7/28/2013 4.3 0.0 0.0 0.0 72.3 10.6 0.0 2.1 10.6
7/28/2013 8/19/2013 12.9 0.0 0.0 0.0 80.9 0.0 0.0 0.0 6.2
8/19/2013 8/31/2013 7.2 2.2 0.7 1.4 23.0 53.2 7.9 0.7 3.6
8/31/2013 9/24/2013 — — — — — — — — —
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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FERC Project No. 14241 Page 101 November 2015
Table 5.1-5. Values of density, taxonomic richness, and relative abundance by habitat from adult emergence trap samples collected in 2013 during the
open water season for sites within the Indian River Focus area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity
Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Density
(per sq m)
per day
Taxa
Richness EPT Taxa Mayfly (E)
Taxa
Stonefly (P)
Taxa
Caddisfly
(T) Taxa
Percent
Aquatic
Taxa
Percent
Terrestrial
Taxa
Percent
Undeter-
mined
RP-141-1 Tributary
Mouth
6/25/2013 7/30/2013 115.9 13 3 2 0 1 97.3 2.7 0
7/30/2013 8/7/2013 289.8 8 3 1 1 1 99.4 0.6 0
8/7/2013 8/17/2013 — — — — — — — — —
8/17/2013 9/25/2013 — — — — — — — — —
RP-141-2 Side
Channel
6/25/2013 7/30/2013 12.6 14 3 1 2 0 93.7 6.3 0
7/30/2013 8/18/2013 34.1 7 4 1 2 1 99.6 0.4 0
8/18/2013 9/26/2013 — — — — — — — — —
RP-141-3
Mult Split
Main
Channel
6/27/2013 7/30/2013 — — — — — — — — —
7/30/2013 8/17/2013 10.2 8 1 0 1 0 1.5 63.6 34.8
8/17/2013 9/25/2013 — — — — — — — — —
RP-141-4 Upland
Slough
6/27/2013 7/30/2013 53.7 21 1 0 0 1 86.5 13.5 0
7/30/2013 8/18/2013 — — — — — — — — —
8/18/2013 9/26/2013 — — — — — — — — —
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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FERC Project No. 14241 Page 102 November 2015
Table 5.1-6. Taxonomic composition metric values from adult emergence trap samples collected in 2013 during the open water season for sites within
the Indian River Focus area (FA-141) in the Middle River Segment of the Susitna River for the River Productivity Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent
Coleoptera
Percent
Chironomids
Percent
Other
Diptera
Percent
Hymeno-
ptera
Percent
Hemiptera
Percent
Others
RP-141-1 Tributary
Mouth
6/25/2013 7/30/2013 1.1 0.0 1.6 0.3 89.3 5.8 0.5 0.5 0.8
7/30/2013 8/7/2013 0.3 0.3 1.0 0.0 50.8 47.3 0.0 0.0 0.3
8/7/2013 8/17/2013 — — — — — — — — —
8/17/2013 9/25/2013 — — — — — — — — —
RP-141-2 Side
Channel
6/25/2013 7/30/2013 0.6 25.8 0.0 1.3 64.8 3.1 1.3 0.6 2.5
7/30/2013 8/18/2013 1.7 27.5 0.4 0.0 68.2 1.7 0.4 0.0 0.0
8/18/2013 9/26/2013 — — — — — — — — —
RP-141-3
Mult Split
Main
Channel
6/27/2013 7/30/2013 — — — — — — — — —
7/30/2013 8/17/2013 0.0 1.5 0.0 1.5 0.0 28.8 1.5 60.6 6.1
8/17/2013 9/25/2013 — — — — — — — — —
RP-141-4 Upland
Slough
6/27/2013 7/30/2013 0.0 0.0 0.3 0.9 22.3 70.2 0.6 3.1 2.5
7/30/2013 8/18/2013 — — — — — — — — —
8/18/2013 9/26/2013 — — — — — — — — —
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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Table 5.1-7. Values of density, taxonomic richness, and relative abundance by habitat from adult emergence trap samples collected in 2013 during the
open water season for sites within the Whiskers Slough Focus area (FA-104) in the Middle River Segment of the Susitna River for the River
Productivity Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Density
(per sq m)
per day
Taxa
Richness EPT Taxa Mayfly (E)
Taxa
Stonefly (P)
Taxa
Caddisfly
(T) Taxa
Percent
Aquatic
Taxa
Percent
Terrestrial
Taxa
Percent
Undeter-
mined
RP-104-1
Tributary
Mouth/
Side
Slough
6/23/2013 8/1/2013 11.5 11 2 0 0 2 95.1 4.9 0
8/1/2013 8/12/2013 44.4 10 1 1 0 0 97.2 2.8 0
8/12/2013 8/30/2013 38.0 6 1 1 0 0 98.8 1.2 0
8/30/2013 9/27/2013 7.2 10 1 0 0 1 82.2 17.8 0
RP-104-2 Side
Slough
6/19/2013 8/1/2013 29.9 11 4 2 1 1 98.3 1.7 0
8/1/2013 8/12/2013 3.8 5 0 0 0 0 93.3 6.7 0
8/12/2013 9/1/2013 — — — — — — — — —
9/1/2013 9/27/2013 7.3 13 2 1 0 1 51.5 48.5 0
RP-104-3 Main
Channel
6/21/2013 8/1/2013 1.2 7 1 0 1 0 41.2 17.6 41.2
8/1/2013 8/13/2013 3.9 5 1 0 1 0 94.1 5.9 0
8/13/2013 9/1/2013 16.7 21 0 0 0 0 14.0 86.0 0
9/1/2013 9/30/2013 1.7 10 1 0 1 0 55.6 44.4 0
RP-104-4 Upland
Slough
6/23/2013 8/1/2013 63.2 12 1 1 0 0 98.5 1.5 0
8/1/2013 8/16/2013 169.9 5 1 1 0 0 98.3 1.7 0
8/16/2013 9/1/2013 111.6 6 0 0 0 0 98.8 1.2 0
9/1/2013 9/28/2013 3.2 6 1 1 0 0 87.1 12.9 0
RP-104-5 Side
Channel
6/21/2013 8/1/2013 0.5 2 1 1 0 0 100.0 0.0 0
8/1/2013 8/13/2013 1.9 2 0 0 0 0 87.5 12.5 0
8/16/2013 9/1/2013 — — — — — — — — —
9/1/2013 9/28/2013 — — — — — — — — —
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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FERC Project No. 14241 Page 104 November 2015
Table 5.1-8. Taxonomic composition metric values from adult emergence trap samples collected in 2013 during the open water season for sites within
Whiskers Slough Focus area (FA-104) in the Middle River Segment of the Susitna River for the River Productivity Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent
Coleoptera
Percent
Chironomids
Percent
Other
Diptera
Percent
Hymeno-
ptera
Percent
Hemiptera
Percent
Others
RP-104-1
Tributary
Mouth/
Side
Slough
6/23/2013 8/1/2013 0.0 0.0 3.1 0.6 90.7 2.5 0.6 0.0 2.5
8/1/2013 8/12/2013 1.1 0.0 0.0 0.0 93.8 3.4 0.6 0.6 0.6
8/12/2013 8/30/2013 2.8 0.0 0.0 0.0 94.3 1.6 0.0 0.4 0.8
8/30/2013 9/27/2013 0.0 0.0 39.7 5.5 39.7 8.2 0.0 1.4 5.5
RP-104-2 Side
Slough
6/19/2013 8/1/2013 0.6 2.4 0.4 0.0 94.2 0.6 0.0 1.1 0.6
8/1/2013 8/12/2013 0.0 0.0 0.0 0.0 46.7 46.7 0.0 0.0 6.7
8/12/2013 9/1/2013 — — — — — — — — —
9/1/2013 9/27/2013 4.4 0.0 1.5 0.0 32.4 55.9 4.4 0.0 1.5
RP-104-3 Main
Channel
6/21/2013 8/1/2013 0.0 5.9 0.0 0.0 5.9 58.8 11.8 5.9 11.8
8/1/2013 8/13/2013 0.0 29.4 0.0 0.0 0.0 17.6 5.9 0.0 47.1
8/13/2013 9/1/2013 0.0 0.0 0.0 0.9 7.0 82.5 7.0 0.0 2.6
9/1/2013 9/30/2013 0.0 16.7 0.0 0.0 27.8 33.3 5.6 5.6 11.1
RP-104-4 Upland
Slough
6/23/2013 8/1/2013 0.1 0.0 0.0 0.2 95.8 2.6 0.1 0.3 0.8
8/1/2013 8/16/2013 0.3 0.0 0.0 0.0 97.7 0.3 0.0 1.2 0.6
8/16/2013 9/1/2013 0.0 0.0 0.0 0.0 96.6 2.2 0.2 0.2 0.9
9/1/2013 9/28/2013 6.5 0.0 0.0 0.0 64.5 19.4 0.0 0.0 9.7
RP-104-5 Side
Channel
6/21/2013 8/1/2013 25.0 0.0 0.0 0.0 75.0 0.0 0.0 0.0 0.0
8/1/2013 8/13/2013 0.0 0.0 0.0 0.0 87.5 12.5 0.0 0.0 0.0
8/16/2013 9/1/2013 — — — — — — — — —
9/1/2013 9/28/2013 — — — — — — — — —
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
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FERC Project No. 14241 Page 105 November 2015
Table 5.1-9. Values of density, taxonomic richness, and relative abundance by habitat from adult emergence trap samples collected in 2013 during the
open water season for sites within the Montana Creek Study Area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity
Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Density
(per sq m)
per day
Taxa
Richness EPT Taxa Mayfly (E)
Taxa
Stonefly (P)
Taxa
Caddisfly
(T) Taxa
Percent
Aquatic
Taxa
Percent
Terrestrial
Taxa
Percent
Undeter-
mined
RP-81-1 Upland
Slough
7/1/2013 8/2/2013 42.2 36 0 0 0 0 61.3 38.7 0
8/2/2013 8/14/2013 44.9 17 0 0 0 0 86.6 13.4 0
8/14/2013 9/1/2013 31.6 22 1 1 0 0 78.0 22.0 0
9/1/2013 10/1/2013 — — — — — — — — —
RP-81-2 Tributary
Mouth
6/30/2013 8/2/2013 — — — — — — — — —
8/2/2013 8/15/2013 12.8 6 2 0 1 1 96.7 1.7 1.7
8/15/2013 9/1/2013 — — — — — — — — —
9/1/2013 10/1/2013 — — — — — — — — —
RP-81-3 Split Main
Channel
6/29/2013 8/2/2013 23.2 22 4 0 3 1 93.7 6.3 0
8/2/2013 8/14/2013 30.6 3 2 0 2 0 100.0 0.0 0
8/14/2013 9/1/2013 9.4 10 2 0 2 0 83.6 14.8 1.6
9/1/2013 10/3/2013 1.8 8 1 0 1 0 33.3 66.7 0
RP-81-4 Side
Channel
6/30/2013 8/2/2013 12.5 17 7 2 3 2 89.9 8.8 1.4
8/2/2013 8/15/2013 24.8 17 3 0 2 1 87.9 11.2 0.9
8/15/2013 9/1/2013 6.9 13 4 1 2 1 73.8 26.2 0
9/1/2013 10/3/2013 — — — — — — — — —
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 106 November 2015
Table 5.1-10. Taxonomic composition metric values from adult emergence trap samples collected in 2013 during the open water season for sites within
the Montana Creek Study Area (RP-81) in the Lower River Segment of the Susitna River for the River Productivity Study.
Sampling
Site Habitat Deployment
Date
Collection
Date
Percent
Mayflies
Percent
Stoneflies
Percent
Caddisflies
Percent
Coleoptera
Percent
Chironomids
Percent
Other
Diptera
Percent
Hymeno-
ptera
Percent
Hemiptera
Percent
Others
RP-81-1 Upland
Slough
7/1/2013 8/2/2013 0.0 0.0 0.0 2.5 28.2 64.2 2.1 3.1 0.0
8/2/2013 8/14/2013 0.0 0.0 0.0 0.5 58.2 36.6 1.5 0.0 3.1
8/14/2013 9/1/2013 1.5 0.0 0.0 0.5 55.6 33.7 1.0 1.0 6.8
9/1/2013 10/1/2013 — — — — — — — — —
RP-81-2 Tributary
Mouth
6/30/2013 8/2/2013 — — — — — — — — —
8/2/2013 8/15/2013 0.0 13.3 3.3 0.0 60.0 23.3 0.0 0.0 0.0
8/15/2013 9/1/2013 — — — — — — — — —
9/1/2013 10/1/2013 — — — — — — — — —
RP-81-3 Split Main
Channel
6/29/2013 8/2/2013 0.0 10.6 0.4 0.4 56.0 29.2 1.4 0.7 1.4
8/2/2013 8/14/2013 0.0 8.3 0.0 0.0 91.7 0.0 0.0 0.0 0.0
8/14/2013 9/1/2013 0.0 26.2 0.0 3.3 57.4 3.3 6.6 3.3 0.0
9/1/2013 10/3/2013 0.0 4.8 0.0 4.8 28.6 - 33.3 19.0 9.5
RP-81-4 Side
Channel
6/30/2013 8/2/2013 5.4 11.5 3.4 0.0 56.1 18.9 3.4 0.0 1.4
8/2/2013 8/15/2013 0.0 10.3 2.6 0.9 62.1 17.2 4.3 0.0 2.6
8/15/2013 9/1/2013 7.1 40.5 2.4 2.4 19.0 26.2 0.0 0.0 2.4
9/1/2013 10/3/2013 — — — — — — — — —
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 107 November 2015
Table 5.1-11. 2013 overall summary of LWD (Snag) metrics for sites at River Productivity stations in Middle
Reach above Devils Canyon.
Station FA-184 (Watana Dam) FA-173 (Stephan Lake Complex)
Site 184-1 184-2 184-3 173-1 173-2 173-3 173-4
Habitat TM SC MC TM MC SC SS
Number of Reps 10 1 0 6 0 3 8
Density (Individuals/m2)
Range 946 - 9400 140.1 — 49 - 1817 — 328 - 819 248 - 10045
Average 4822.1 140.1 — 576.9 — 588.2 2689.7
Median 4655.9 140.1 — 263.5 — 617.3 1480.0
Taxa Richness (number)
Range 17 - 34 6 — 4 - 20 — 9 - 21 6 - 26
Average 23.8 6.0 — 10.2 — 15.3 14.6
Median 21 6 — 8 — 16 14.5
EPT Taxa (number)
Range 3 - 8 1 — 0 - 5 — 0 - 1 0 - 2
Average 5.5 1.0 — 1.3 — 0.3 1.0
Median 5.5 1 — 0 — 0 1
Chironomid Taxa (number)
Range 8 - 22 3 — 2 - 11 — 7 - 16 6 - 18
Average 14.4 3.0 — 6.0 — 12.0 10.9
Median 14 3 — 5 — 13 11
Diversity (H')
Range 1.21 - 2.69 1.52 — 1.13 - 2.44 — 1.13 - 2.61 0.87 - 2.76
Average 1.99 1.52 — 1.79 — 2.07 1.78
Median 2.16 1.52 — 1.87 — 2.47 1.98
Evenness (J')
Range 0.42 - 0.78 0.85 — 0.68 - 1 — 0.51 - 0.94 0.4 - 0.85
Average 0.63 0.85 — 0.84 — 0.76 0.67
Median 0.68 0.85 — 0.83 — 0.81 0.71
Relative Abundance Top 3 Taxa (Percent)
Range 50.6 - 85 76.9 — 42.9 - 91.7 — 35.3 - 85 42.7 - 95.9
Average 67.7 76.9 — 65.8 — 57.7 71.5
Median 62.9 76.9 — 69.1 — 52.9 69.1
Relative Abundance EPT (Percent)
Range 3.1 - 76 38.5 — 0 - 49.7 — 0 - 2.5 0 - 6.1
Average 22.0 38.5 — 14.1 — 0.8 1.8
Median 7.7 38.5 — 0.0 — 0.0 1.8
Relative Abundance Chironomids (Percent)
Range 12.4 - 90.2 23.1 — 41.7 - 71.4 — 91.2 - 95 83.1 - 100
Average 53.4 23.1 — 53.4 — 93.3 90.5
Median 51.1 23.1 — 47.2 — 93.6 91.0
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 108 November 2015
Table 5.1-12. 2013 overall summary of LWD (Snag) metrics for sites at River Productivity stations in Middle Reach below Devils Canyon.
Station FA-141 (Indian River) FA-104 (Whiskers Slough)
Site 141-1 141-2 141-3 141-4 104-1 104-2 104-3 104-4 104-5
Habitat TM SC MC US TM SS MC US SC
Number of Reps 13 6 0 12 12 18 0 13 7
Density (Individuals/m2)
Range 283 - 28318 110 - 2889 — 155 - 3448 557 - 12529 6.9 - 4386 — 78 - 4394 671 - 3882
Average 7273.0 892.6 — 1432.6 3975.3 1794.8 — 1438.7 2476.7
Median 3890.7 547.2 — 1263.2 1777.9 1418.1 — 994.3 2764.4
Taxa Richness (number)
Range 6 - 37 5 - 27 — 8 - 30 8 - 32 1 - 29 — 7 - 36 7 - 25
Average 19.2 15.2 — 16.0 22.8 17.8 — 19.8 15.6
Median 17 15 — 14.5 23 17.5 — 22 14
EPT Taxa (number)
Range 1 - 11 1 - 5 — 0 - 6 0 - 5 0 - 4 — 0 - 6 1 - 6
Average 4.1 3.2 — 1.7 1.8 1.7 — 1.8 3.3
Median 3 3 — 1 1.5 1.5 — 1 3
Chironomid Taxa (number)
Range 5 - 19 3 - 15 — 4 - 21 6 - 19 0 - 21 — 4 - 26 3 - 18
Average 11.3 8.5 — 10.5 15.9 13.3 — 13.2 10.9
Median 10 8 — 9.5 17 12 — 14 11
Diversity (H')
Range 1.28 - 2.87 1.61 - 2.59 — 1.25 - 3.03 1.29 - 2.85 0 - 2.65 — 0.88 - 2.87 0.77 - 2.26
Average 2.04 2.02 — 1.99 2.26 2.00 — 2.07 1.49
Median 1.95 1.94 — 1.88 2.36 2.1 — 1.98 1.25
Relative Abundance Top 3 Taxa (Percent)
Range 43.2 - 84.4 47.2 - 72.2 — 35.4 - 88.8 31.3 - 86.5 44.9 - 100 — 42.2 - 91.3 58.3 - 95.4
Average 66.6 61.8 — 65.0 57.0 65.6 — 63.4 81.7
Median 68.3 64.2 — 70.4 55.9 65.4 — 56.6 89.8
Relative Abundance EPT (Percent)
Range 3.8 - 19.7 12.7 - 38.6 — 0 - 47.7 0 - 35.1 0 - 52.9 — 0 - 12.5 3.1 - 27.8
Average 9.4 24.6 — 8.2 4.9 5.8 — 3.8 12.0
Median 6.6 23.6 — 1.2 0.9 1.9 — 2.1 11.3
Relative Abundance Chironomids (Percent)
Range 31.3 - 91.6 48.2 - 76.1 — 19 - 94.4 54.3 - 97.7 0 - 89.6 — 10.5 - 78 42.1 - 96.9
Average 69.4 62.9 — 63.2 85.7 65.1 — 49.4 79.3
Median 77.1 61.1 — 64.7 88.7 70.3 — 58.3 85.6
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Table 5.1-13. 2013 overall summary of LWD (Snag) metrics for sites at River Productivity stations in Lower
Reach downstream of confluence with Chulitna River.
Station RP-81 (Montana Creek)
Site 81-1 81-2 81-3 81-4
Habitat US TM MC SC
Number of Reps 12 15 4 15
Density (Individuals/m2)
Range 0 - 1660.4 0 - 16002.4 21 - 213.3 23- 9624
Average 597.3 3347.3 93.7 1222.0
Median 247.1 1251.5 70.0 476.7
Taxa Richness (number)
Range 0 - 23 0 - 31 2 - 8 4 - 29
Average 11.1 16.8 4.3 13.8
Median 10 16 3.5 12
EPT Taxa (number)
Range 0 - 3 0 - 9 0 - 4 3 - 7
Average 0.6 3.1 1.8 4.4
Median 0 3 1.5 4
Chironomid Taxa (number)
Range 0 - 18 0 - 18 0 - 4 0 - 19
Average 8.1 11.1 2.5 7.7
Median 6 12 3 6
Diversity (H')
Range 0 - 2.58 0 - 2.82 0.41 - 1.58 1.32 - 2.72
Average 1.65 1.89 1.06 1.95
Median 2.14 2.06 1.13 1.82
Relative Abundance Top 3 Taxa (Percent)
Range 0 - 100 0 - 91.2 78.8 - 100 42.1 - 87.5
Average 52.9 60.5 91.1 67.1
Median 50.0 61.5 92.9 71.4
Relative Abundance EPT (Percent)
Range 0 - 21.4 0 - 73.6 0 - 100 15.1 - 100
Average 3.4 13.8 44.6 50.3
Median 0.0 9.4 39.2 46.1
Relative Abundance Chironomids (Percent)
Range 0 - 87.7 0 - 89.5 0 - 100 0 - 76.2
Average 55.2 56.0 55.4 36.5
Median 79.2 65.2 60.8 39.7
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Table 5.2-1. 2014 overall summary of drift and plankton metrics for sites at River Productivity stations in Middle Reach above Devils Canyon.
Station FA-184 (Watana Dam) FA-173 (Stephan Lake Complex)
Site 184-1 184-2 184-3 184-4 173-1 173-2 173-3 173-4 173-5
Metric Habitat TM SC MC
MC/Above
TM TM MC SC SS US
Density
(Individuals/ft3)
Range 0.22 - 4.27 0.03 - 2.12 0.03 - 0.86 0.138 - 1 0.09 - 1.07 0.05 - 0.65 0.29 - 13.3 0.13 - 12.6 0.4 - 137.7
Average 1.66 0.82 0.30 0.43 0.42 0.29 2.49 3.18 43.82
Median 1.37 0.58 0.19 0.36 0.36 0.26 0.60 1.28 31.22
Taxa Richness
(number)
Range 13 - 60 23 - 39 25 - 51 18 - 46 24 - 54 36 - 57 5 - 47 2 - 18 12 - 30
Average 35.3 30.2 36.0 35.7 38.8 42.8 20.9 7.4 20.2
Median 33.00 30.00 35.00 37.00 40.50 39.50 12.00 5.00 21.00
EPT Taxa
(number)
Range 3 - 8 2 - 8 2 - 9 0 - 7 3 - 7 4 - 7 0 - 10 0 - 1 0 - 1
Average 5.7 4.8 5.0 4.5 5.2 5.5 2.7 0.1 0.1
Median 5.50 4.50 4.50 5.00 5.50 5.00 1.00 0.00 0.00
Chironomid
Taxa (number)
Range 4 - 34 5 - 27 10 - 24 9 - 25 9 - 25 12 - 31 2 - 16 1 - 10 8 - 17
Average 18.2 14.2 16.2 15.3 16.8 20.3 8.2 4.7 11.8
Median 15.50 13.00 15.50 15.50 18.00 19.00 7.00 4.00 12.00
Diversity (H')
Range 1.09 - 3.54 1.96 - 3 2.48 - 3.13 2.31 - 3.04 2.02 - 3.39 2.67 - 3.37 1.43 - 3.03 0.55 - 2.13 1.51 - 2.69
Average 2.27 2.58 2.83 2.81 2.82 3.05 2.17 1.38 2.10
Median 2.30 2.62 2.86 2.88 3.07 3.11 1.71 1.41 2.12
Relative
Abundance Top
3 Taxa (Percent)
Range 26.7 - 85.5 29.7 - 68.6 40.4 - 54.1 37.8 - 57.7 30.1 - 71.9 27.9 - 50.3 37.5 - 79.3 60 - 100 47 - 80.7
Average 59.0 50.5 45.4 46.0 44.6 39.3 60.6 80.7 63.6
Median 60.07 51.41 44.03 44.68 35.74 39.95 71.43 82.26 61.59
Relative
Abundance EPT
(Percent)
Range 5.1 - 12.7 2.1 - 16.5 2.7 - 17.3 0 - 15.1 3.4 - 42.9 4.2 - 29.1 0 - 16.7 0 - 2.5 0 - 0.7
Average 8.6 8.3 9.3 8.2 17.0 14.5 6.3 0.3 0.1
Median 8.28 9.55 9.31 7.52 5.91 14.73 1.96 0.00 0.00
Relative
Abundance
Chironomids
(Percent)
Range 11.2 - 91.5 8.7 - 84.6 15.6 - 81.6 17.8 - 85.5 20.8 - 74.3 14.4 - 82.5 47.1 - 72.5 19.4 - 100 29.4 - 97.3
Average 58.6 52.6 49.7 49.6 53.8 47.5 57.4 60.0 62.4
Median 72.81 64.88 50.58 45.67 60.27 48.97 57.66 50.00 61.59
Relative
Abundance
Zooplankton
(Percent)
Range 0 - 1.8 0 - 51.7 2.7 - 40.1 0 - 36.5 0 - 5.8 0.4 - 40.1 0 - 28.6 0 - 10.8 0 - 16.8
Average 0.7 13.4 17.4 15.4 1.2 14.2 9.3 1.6 5.2
Median 0.31 3.01 10.19 13.26 0.31 7.28 5.88 0.00 4.35
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Table 5.2-2. 2014 overall summary of drift and plankton metrics for sites at River Productivity stations in Middle Reach below Devils Canyon.
Station FA-141 (Indian River) FA-104 (Whiskers Slough)
Site 141-1 141-2 141-3 141-4 141-5 104-1 104-2.1 104-2 104-3 104-4 104-5
Metric
Habitat TM SC MC US
MC/Above
TM TM
SS/Above
TM SS MC US SC
Density
(Individuals/ft3)
Range 0.04 - 0.34 0.012 - 1.96 0.006 - 0.26 0.374 - 9.11 0.069 - 0.43 0.102 - 6.24 0.062 - 3.58 0.08 - 10.48 0.03 - 0.21 0.21 - 121.8 0.01 - 0.48
Average 0.17 0.67 0.10 2.39 0.20 2.21 1.14 2.05 0.08 15.83 0.15
Median 0.15 0.44 0.08 2.06 0.15 0.71 0.59 0.84 0.05 1.31 0.11
Taxa Richness
(number)
Range 41 - 55 1 - 40 18 - 42 4 - 18 30 - 38 4 - 37 1 - 12 1 - 19 20 - 35 2 - 40 11 - 26
Average 48.8 15.0 33.2 9.3 33.2 19.4 5.6 6.7 27.7 12.1 19.8
Median 49.50 10.00 38.50 10.00 33.00 15.00 5.00 5.00 26.50 8.00 20.50
EPT Taxa
(number)
Range 4 - 11 0 - 6 0 - 7 0 - 1 3 - 8 0 - 7 0 - 2 0 - 1 0 - 6 0 - 3 0 - 5
Average 7.7 1.6 4.5 0.3 5.2 2.4 0.3 0.1 3.8 0.6 2.7
Median 8.50 1.00 5.50 0.00 5.00 1.00 0.00 0.00 5.00 0.00 3.00
Chironomid Taxa
(number)
Range 17 - 35 1 - 16 12 - 19 1 - 12 11 - 20 0 - 18 0 - 6 0 - 9 8 - 25 0 - 23 5 - 13
Average 23.7 8.0 15.3 5.1 15.5 9.7 2.4 3.1 14.2 6.8 9.7
Median 23.00 6.00 15.00 5.00 14.50 8.00 2.00 2.00 13.50 4.00 10.00
Diversity (H')
Range 3.01 - 3.3 0 - 3.2 2.68 - 3.02 1.13 - 2.45 2.33 - 3.07 1.32 - 3 0 - 2.27 0 - 2.12 1.81 - 3.13 0.56 - 3.26 2.27 - 2.79
Average 3.15 2.06 2.84 1.81 2.61 2.17 1.20 1.42 2.52 1.76 2.53
Median 3.13 2.24 2.85 1.69 2.52 2.10 1.39 1.45 2.71 1.75 2.59
Relative
Abundance Top 3
Taxa (Percent)
Range 35.7 - 39.2 34.2 - 100 32.1 - 50.8 37.9 - 96.3 32.2 - 65 40 - 87.5 50 - 100 60.2 - 100 34.4 - 74 29 - 100 38.2 - 57.6
Average 37.8 55.6 42.3 66.0 53.3 61.8 81.5 79.4 53.0 69.0 49.7
Median 38.50 45.93 41.35 67.44 59.16 63.10 80.56 75.00 46.26 71.43 51.18
Relative
Abundance EPT
(Percent)
Range 8.7 - 40.5 0 - 16.9 0 - 16.7 0 - 33.3 8.1 - 13 0 - 36.8 0 - 11.1 0 - 1 0 - 15.2 0 - 28.6 0 - 36.4
Average 21.5 5.2 9.1 2.9 9.6 9.5 1.4 0.1 8.2 3.9 13.4
Median 13.64 4.17 8.11 0.00 8.39 5.23 0.00 0.00 9.34 0.00 7.95
Relative
Abundance
Chironomids
(Percent)
Range 23.1 - 76.9 56.4 - 100 30.2 - 75.8 16 - 71.4 34.9 - 81.5 0 - 49.3 0 - 100 0 - 87.5 53.2 - 83.1 0 - 77.9 39.4 - 64.7
Average 55.3 69.8 57.8 44.4 63.3 35.6 32.8 43.0 66.5 41.7 54.1
Median 66.19 66.67 59.76 45.32 73.55 41.83 26.39 39.58 64.93 45.96 55.40
Relative
Abundance
Zooplankton
(Percent)
Range 0 - 6.4 0 - 33.3 0 - 25.9 0 - 33.3 0 - 17.6 0 - 62.5 0 - 33.3 0 - 40.8 0 - 7.8 0 - 28.6 0 - 10.9
Average 2.5 10.2 8.6 9.3 5.9 26.4 10.1 14.4 4.7 5.6 6.1
Median 1.58 4.17 3.66 7.32 0.58 22.03 2.44 12.50 4.83 1.55 6.52
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Table 5.2-3. 2014 overall summary of drift and plankton metrics for sites at River Productivity stations in
Lower Reach downstream of confluence with Chulitna River.
Station RP-81 (Montana Creek)
Site 81-1 81-2 81-3 81-4 81-5
Metric Habitat US TM MC SC
SC/Above
TM
Density
(Individuals/ft3)
Range 0 - 52.83 0.13 - 0.97 0.05 - 0.19 0.001 - 0.04 0.011 - 0.15
Average 16.26 0.33 0.11 0.02 0.08
Median 13.97 0.21 0.10 0.03 0.09
Taxa Richness
(number)
Range 0 - 19 31 - 49 30 - 56 4 - 32 22 - 36
Average 8.2 40.7 43.0 19.3 30.0
Median 7.00 42.50 44.00 20.50 31.50
EPT Taxa
(number)
Range 0 - 1 4 - 11 3 - 8 1 - 6 2 - 5
Average 0.1 7.8 5.3 3.5 3.7
Median 0.00 8.00 5.00 4.00 4.00
Chironomid Taxa
(number)
Range 0 - 9 12 - 25 15 - 19 2 - 14 10 - 17
Average 4.1 18.3 17.5 9.8 14.0
Median 4.00 18.50 18.00 12.00 14.00
Diversity (H')
Range 0 - 2.3 2.33 - 3.15 2.45 - 3.27 1.37 - 3.17 1.53 - 3.09
Average 1.11 2.81 2.83 2.48 2.47
Median 1.56 2.95 2.70 2.51 2.79
Relative
Abundance Top 3
Taxa (Percent)
Range 0 - 100 29.1 - 58.4 34 - 57 29.4 - 80 31.4 - 79
Average 75.5 44.5 48.7 49.5 52.4
Median 77.11 44.30 54.99 44.19 44.29
Relative
Abundance EPT
(Percent)
Range 0 - 2.1 2.9 - 14.4 7.8 - 51.5 8.7 - 27.4 3.6 - 33.3
Average 0.2 8.4 23.8 16.4 19.6
Median 0.00 7.86 11.42 15.93 22.75
Relative
Abundance
Chironomids
(Percent)
Range 0 - 100 56 - 84.8 21.1 - 44 46.7 - 62.3 22.5 - 60
Average 41.3 71.1 36.2 54.7 38.2
Median 48.51 72.14 41.89 55.38 36.05
Relative
Abundance
Zooplankton
(Percent)
Range 0 - 98.7 0.4 - 10.4 0 - 9.3 0 - 6.7 1.5 - 22.4
Average 33.7 4.2 3.6 2.5 7.6
Median 3.23 4.34 3.12 1.93 5.64
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Table 5.4-1. Summary of water temperature patterns across years and macrohabitat types. All metrics
calculated from daily mean temperatures at each station.
Year Habitat Water temperature (°C)
Mean Standard
Deviation (SD) Maximum Minimum
2013 Main channel 10.7495 2.79168 16.8819 1.63667
2013 Side channel 9.67468 2.69146 17.2902 4.445
2013 Side slough 7.73464 3.45712 14.575 3.40771
2013 Trib mouth 10.2155 2.79093 15.8727 -0.014375
2013 Upland slough 9.45116 3.0383 15.9369 0.276667
2014 Main channel 10.1632 1.82555 13.8952 2.03036
2014 Side channel 9.24361 2.23946 14.0573 1.99793
2014 Side slough 6.44367 1.81087 12.7231 3.53593
2014 Trib mouth 8.93124 2.24914 15.0177 2.38571
2014 Upland slough 9.115 2.09717 14.1442 3.659
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Table 5.4-2. Bioenergetics model results showing the growth, proportion of maximum consumption (P),
growth efficiency of juvenile Chinook (SCK) and Coho (SCO) salmon. Consumption rates were estimated
from observed growth between the spring and summer (Spr-Sum) sampling events and between the summer
and fall events (Sum-Fal). Model inputs were pooled for combinations of main channel (MC), side channel
(SC), side slough (SS), tributary mouth (TM), and upland slough (US) macrohabitats based on a statistical
analysis of growth patterns. Growth of age-0 Coho Salmon did not differ among SC, SS, TM, and US
habitats, so inputs were pooled across these habitat types (All).
Species Age Year Interval Habitats Initial
weight (g)
Final
weight (g)
P, Pro-
portion of
maximum
consum-
ption
Growth
efficiency
(%)
Mean
mass-
specific
consum-
ption rate
(g/g/d)
Mean
mass-
specific
growth
rate
(g/g/d)
Chinook 0 2013 Spr-Sum SS, TM, US 0.80 6.48 0.91 31% 31% 3.48%
Chinook 0 2013 Sum-Fal SS, TM, US 6.48 7.20 0.52 15% 14% 0.31%
Chinook 0 2014 Spr-Sum MC, SC 0.60 4.09 0.97 26% 24% 3.31%
Chinook 0 2014 Spr-Sum SS, TM, US 0.60 2.89 1.12 23% 17% 2.72%
Chinook 0 2014 Sum-Fal MC, SC 4.09 4.54 0.54 6% 17% 0.22%
Chinook 0 2014 Sum-Fal SS, TM, US 2.89 3.36 0.55 9% 11% 0.32%
Coho 0 2013 Spr-Sum SC, SS, TM,
US 0.80 2.76 0.29 31% 11% 2.08%
Coho 0 2013 Sum-Fal SC, SS, TM,
US 2.76 3.36 0.18 23% 8% 0.57%
Coho 0 2014 Spr-Sum SC, SS, TM,
US 0.60 2.57 0.40 27% 13% 2.52%
Coho 0 2014 Sum-Fal SC, SS, TM,
US 2.57 2.71 0.17 4% 8% 0.12%
Coho 1 2013 Spr-Sum SC, TM 4.88 9.27 0.26 27% 28% 1.08%
Coho 1 2013 Spr-Sum SS, US 4.97 7.13 0.26 14% 25% 0.61%
Coho 1 2013 Sum-Fal SS, US 7.13 8.32 0.25 19% 19% 0.45%
Coho 1 2014 Spr-Sum SC, TM 4.53 9.20 0.38 20% 40% 1.23%
Coho 1 2014 Spr-Sum SS, US 5.97 6.81 0.23 7% 20% 0.23%
Coho 1 2014 Sum-Fal SS, US 6.81 6.30 0.13 -11% 10% -0.17%
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Table 5.4-3. Growth rate potential model results showing physical parameters and drift invertebrate biomass
density measured at each sampling event, as well as simulated daily ration, growth rate potential, and
proportion of maximum consumption (P) of age-1 Coho Salmon under the observed conditions. Habitat
types abbreviated as main channel (MC), side channel (SC), side slough (SS), t ributary mouth (TM). Bold
text indicates sites with positive growth rate potential values.
Site Habitat Year Season
Tempera-
ture (ºC)
Drift Invert.
Biomass
Density
(mg dry /
m2 / sec)
Velocity
(m/s)
Turbidity
(NTU)
Daily
Ration (g
wet)
Growth
rate
potential
(g / g /
day) P
RP-184-1 TM 2013 Spring 11.3 0.51 0.51 0.59 0.00 -1.5% 0.00
RP-184-1 TM 2013 Summer 7.9 0.28 0.46 34 0.00 -1.1% 0.00
RP-184-1 TM 2014 Spring 6.3 5.91 0.38 1.04 9.41 2.2% 1.00
RP-184-1 TM 2014 Fall 3.6 2.52 0.35 1.54 4.48 0.7% 1.00
RP-184-2 SC 2014 Spring 9.3 2.34 0.30 45.9 1.51 3.8% 1.00
RP-184-2 SC 2014 Summer 10.5 0.13 0.42 59.7 0.00 -1.4% 0.00
RP-184-3 MC 2014 Spring 9.4 0.31 0.52 35.1 0.00 -1.3% 0.00
RP-184-3 MC 2014 Summer 11.0 0.32 0.45 61.1 0.00 -1.4% 0.00
RP-184-3 MC 2014 Fall 6.6 0.59 0.48 9.58 0.00 -1.0% 0.00
RP-173-1 TM 2013 Spring 10.5 0.18 0.32 7.9 0.42 1.5% 0.47
RP-173-1 TM 2014 Spring 6.9 0.71 0.69 3.53 0.00 -1.0% 0.00
RP-173-1 TM 2014 Summer 8.9 0.25 0.87 1.27 0.00 -1.2% 0.00
RP-173-1 TM 2014 Fall 3.5 2.57 0.98 2 0.00 -0.8% 0.00
RP-173-2 MC 2013 Spring 13.0 0.38 0.52 19 0.00 -1.7% 0.00
RP-173-2 MC 2013 Summer 8.5 0.54 0.69 68.2 0.00 -1.2% 0.00
RP-173-3 SC 2013 Spring 6.3 0.15 0.30 1.07 1.04 2.3% 1.00
RP-173-3 SC 2014 Spring 6.3 0.85 0.32 0.59 6.34 2.2% 1.00
RP-173-3 SC 2014 Summer 7.7 1.04 0.50 3.09 0.00 -1.1% 0.00
RP-141-1 TM 2013 Spring 9.3 2.88 0.90 0.02 0.00 -1.2% 0.00
RP-141-1 TM 2013 Summer 8.8 0.85 0.75 0.95 0.00 -1.2% 0.00
RP-141-1 TM 2013 Fall 7.4 1.14 0.34 0.69 3.50 2.9% 1.00
RP-141-1 TM 2014 Spring 8.0 0.43 0.35 0.63 2.08 3.3% 1.00
RP-141-1 TM 2014 Summer 9.6 0.63 0.40 2.32 0.20 0.1% 0.24
RP-141-1 TM 2014 Fall 6.1 0.67 0.59 5.26 0.00 -0.9% 0.00
RP-141-2 SC 2013 Spring 11.8 0.42 0.38 99 0.02 -1.4% 0.02
RP-141-2 SC 2013 Summer 8.4 0.03 0.30 16 0.03 -0.9% 0.05
RP-141-3 MC 2013 Spring 12.0 0.03 0.52 106 0.00 -1.6% 0.00
RP-141-3 MC 2013 Summer 9.4 0.19 0.61 24 0.00 -1.3% 0.00
RP-141-3 MC 2014 Spring 9.8 0.01 0.32 21.7 0.01 -1.2% 0.01
RP-141-3 MC 2014 Summer 11.7 0.21 0.43 47 0.00 -1.5% 0.00
RP-141-3 MC 2014 Fall 5.3 0.27 0.49 13.3 0.00 -0.9% 0.00
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Table 5.4-3 (cont.). Growth rate potential model results showing physical parameters and drift invertebrate
biomass density measured at each sampling event, as well as simulated daily ration, growth rate potential,
and proportion of maximum consumption (P) of age-1 Coho Salmon under the observed conditions. Habitat
types abbreviated as main channel (MC), side channel (SC), side slough (SS), tributary mouth (TM). Bold
text indicates sites with positive growth rate potential values.
Site Habitat Year Season
Tempera-
ture (ºC)
Drift Invert.
Biomass
Density
(mg dry /
m2 / sec)
Velocity
(m/s)
Turbidity
(NTU)
Daily
Ration (g
wet)
Growth
rate
potential
(g / g /
day) P
RP-104-2 SS 2013 Spring 12.5 0.70 0.46 46 0.00 -1.6% 0.00
RP-104-3 MC 2013 Spring 14.4 0.24 0.69 115 0.00 -2.0% 0.00
RP-104-3 MC 2013 Summer 9.6 0.12 0.37 600 0.01 -1.2% 0.01
RP-104-3 MC 2014 Summer 12.4 0.12 0.32 45.7 0.05 -1.2% 0.06
RP-104-3 MC 2014 Fall 6.8 0.26 0.46 27.1 0.00 -1.0% 0.00
RP-104-5 SC 2013 Spring 14.4 0.24 0.43 111 0.00 -1.9% 0.00
RP-104-5 SC 2014 Spring 10.2 0.46 0.32 15.7 0.67 3.0% 0.77
RP-104-5 SC 2014 Fall 7.8 0.20 0.30 46.5 0.07 -0.6% 0.11
RP-81-2 TM 2013 Spring 11.3 0.60 0.69 0.41 0.00 -1.5% 0.00
RP-81-2 TM 2013 Fall 6.5 0.09 0.62 1.18 0.00 -1.0% 0.00
RP-81-2 TM 2014 Summer 13.0 0.38 0.59 1.52 0.00 -1.7% 0.00
RP-81-2 TM 2014 Fall 9.5 0.49 0.30 2.96 1.31 3.8% 1.00
RP-81-3 MC 2013 Summer 9.5 0.11 0.35 66 0.02 -1.1% 0.02
RP-81-3 MC 2014 Spring 10.5 0.13 0.44 35.1 0.00 -1.4% 0.00
RP-81-3 MC 2014 Fall 7.8 0.55 0.40 16 0.03 -0.9% 0.04
RP-81-4 SC 2013 Summer 9.6 0.45 0.79 85 0.00 -1.3% 0.00
RP-81-4 SC 2014 Spring 9.7 0.06 0.47 49 0.00 -1.3% 0.00
RP-81-4 SC 2014 Summer 10.4 0.16 0.34 35 0.07 -0.9% 0.08
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Table 5.4-4. Results of MixSIAR Bayesian stable isotope diet models performed for juvenile Chinook and
Coho salmon, and Arctic Grayling and the potential freshwater, marine, and terrestrial prey categories for
all study sites with sufficient sample size (n > 2) in the Spring 2014 sampling event.
Season Sampling
Site
Macrohabitat
type
Consumer
species (n)
Mean % contribution (2.5%, 97.5% CI)
Freshwater Marine Terrestrial
Spring
184-3 Side channel SCK (3) 70.0 (37.1, 94.8) 12.6 (0.5, 40.8) 17.4 (0.7, 48.6)
GRA (7) 78.5 (61.6, 93.0) 6.3 (0.4, 14.9) 15.2 (2.9, 31.0)
RP-141-1 Tributary mouth SCO (5) 61.3 (39.3, 80.9) 17.6 (4.9, 30.1) 21.1 (5.3, 41.6)
RP-141-2 Side channel SCK (4) 57.7 (24.3, 86.8) 10.1 (0.4, 32.5) 32.2 (6.6, 67.6)
RP-141-3 Main channel SCK (8) 73.1 (48.1, 92.8) 10.1 (0.7, 21.7) 16.8 (1.9, 40.6)
GRA (3) 63.4 (29.7, 90.7) 13.1 (0.9, 29.8) 23.6 (2.1, 54.8)
RP-104-1 Tributary mouth SCK (6) 58.1 (43.6, 73.8) 17.0 (6.8, 26.1) 24.8 (11.7, 39.7)
SCO (10) 61.3 (48.3, 75.5) 14.3 (6.1, 22.3) 24.4 (12.7, 37.3)
RP-104-2 Side slough SCO (5) 57.3 (33.9, 79.4) 15.3 (1.8, 29.6) 27.4 (7.0, 55.4)
RP-104-4 Upland slough SCO (4) 68.6 (51.9, 83.9) 23.0 (8.6, 33.6) 8.4 (0.5, 24.7)
RP-104-5 Side channel SCO (3) 57.9 (14.8, 91.5) 21.6 (0.9, 63.8) 20.5 (0.6, 62.1)
RP-81-1 Upland slough SCO (6) 66.7 (42.8, 92.9) 19.1 (0.6, 40.7) 14.2 (0.7, 38.8)
RP-81-2 Tributary mouth SCO (4) 69.7 (37.5, 93.2) 14.3 (0.9, 37.9) 16.0 (1.1, 45.4)
RP-81-3 Main channel SCK (3) 64.0 (27.0, 93.1) 12.9 (0.3, 43.6) 23.2 (1.6, 60.0)
SCO (6) 64.9 (33.8, 90.0) 10.1 (0.4, 30.2) 25.0 (4.1, 56.1)
RP-81-4 Side channel SCK (5) 62.8 (32.9, 89.7) 13.2 (0.5, 32.4) 24.0 (3.1, 56.1)
Table 5.4-5. Results of MixSIAR Bayesian stable isotope diet models performed for juvenile Chinook and
Coho salmon, and Arctic Grayling and the potential freshwater, marine, and terrestrial prey categories for
all study sites with sufficient sample size (n > 2) in the Summer 2014 sampling event.
Season Sampling
Site
Macrohabitat
type
Consumer
species (n)
Mean % contribution (2.5%, 97.5% CI)
Freshwater Marine Terrestrial
Summer
RP-184-1 Tributary mouth GRA (6) 67.5 (30.4, 93.6) 5.9 (0.1, 22.8) 26.6 (2.5, 62.8)
RP-184-2 Main channel GRA (6) 56.3 (29.3, 80.6) 9.5 (0.8, 19.8) 34.2 (11.9, 62.4)
RP-184-3 Side channel GRA (5) 72.7 (42.3, 94.3) 9.3 (0.5, 26.5) 17.9 (1.5, 47.1)
RP-141-1 Tributary mouth SCK (7) 62.9 (39.4, 87.7) 12.0 (4.0, 20.5) 25.1 (3.9, 46.9)
RP-141-2 Side channel SCK (8) 53.2 (30.9, 79.7) 7.8 (0.5, 17.3) 39.0 (13.3, 63.9)
RP-141-3 Main channel SCK (8) 43.8 (24.0, 64.0) 14.7 (4.1, 24.2) 41.5 (21.3, 65.1)
RP-141-4 Upland slough SCK (5) 61.6 (38.8, 83.2) 26.6 (5.3, 41.6) 11.8 (0.5, 35.9)
RP-104-1 Tributary mouth SCO (6) 53.4 (34.9, 73.5) 6.0 (0.2, 16.9) 40.6 (19.5, 61.3)
RP-104-3 Main channel SCK (10) 65.6 (46.4, 82.9) 8.4 (1.0, 17.4) 26.0 (8.1, 46.9)
RP-104-4 Upland slough SCO (8) 67.7 (47.1, 88.8) 3.9 (0.1, 12.6) 28.4 (7.5, 50.2)
SCK (5) 75.9 (53.4, 95.5) 3.5 (0.1, 12.7) 20.6 (1.5, 44.0)
RP-104-5 Side channel SCO (4) 71.1 (39.1, 95.4) 16.5 (0.6, 39.2) 12.4 (0.3, 42.2)
SCK (8) 50.1 (25.5, 73.8) 5.8 (0.3, 13.9) 44.1 (20.9, 68.9)
RP-81-1 Upland slough SCO (8) 58.3 (35.5, 86.6) 16.0 (1.0, 33.4) 25.6 (4.4, 51.0)
SCK (4) 45.6 (15.7, 83.0) 17.9 (0.4, 44.2) 36.5 (7.5, 69.2)
RP-81-2 Tributary mouth SCO (6) 68.0 (42.9, 90.5) 8.9 (0.6, 20.2) 23.1 (4.5, 47.9)
SCK (6) 54.3 (26.7, 87.0) 7.1 (0.3, 19.3) 38.6 (7.3, 66.8)
RP-81-3 Main channel SCK (8) 64.2 (40.7, 84.3) 5.4 (0.3, 14.1) 30.3 (11.8, 54.8)
RP-81-4 Side channel SCK (3) 52.1 (17.3, 85.6) 12.4 (0.3, 45.4) 35.5 (6.4, 72.3)
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Table 5.4-6. Results of MixSIAR Bayesian stable isotope diet models performed for juvenile Chinook and
Coho salmon, and Arctic Grayling and the potential freshwater, marine, and terrestrial prey categories for
all study sites with sufficient sample size (n > 2) in the Fall 2014 sampling event.
Season Sampling
Site
Macrohabitat
type
Consumer
species (n)
Mean % contribution (2.5%, 97.5% CI)
Freshwater Marine Terrestrial
Fall
RP-184-1 Tributary mouth GRA (6) 46.2 (19.2, 74.7) 6.3 (0.2, 21.3) 47.5 (17.5, 76.2)
RP-141-1 Tributary mouth SCK (7) 59.4 (40.5, 77.4) 31.3 (18.4, 42.2) 9.2 (0.3, 26.9)
RP-141-2 Side channel SCK (8) 74.4 (44.0, 96.0) 4.4 (0.1, 18.1) 21.2 (1.5, 53.9)
RP-141-3 Main channel SCK (8) 74.5 (47.5, 94.6) 7.0 (0.2, 18.3) 18.5 (1.5, 45.7)
RP-141-4 Upland slough SCK (3) 34.4 (5.7, 72.8) 38.6 (8.5, 76.7) 27.0 (2.8, 66.1)
RP-104-1 Tributary mouth SCO (8) 64.5 (43.1, 87.3) 6.7 (0.3, 18.6) 28.8 (6.5, 52.7)
SCK (8) 69.6 (45.5, 90.2) 5.8 (0.2, 16.9) 24.7 (4.4, 51.2)
RP-104-2 Side slough SCO (8) 51.1 (3.0, 70.2) 23.5 (10.2, 40.3) 25.4 (6.1, 51.2)
RP-104-3 Main channel SCK (4) 66.7 (36,0, 92.1) 13.5 (1.0, 30.6) 19.8 (1.9, 48.5)
RP-104-4 Upland slough SCO (8) 69.5 (48.2, 90.3) 9.3 (1.4, 18.6) 21.2 (3.3, 42.7)
RP-104-5 Side channel SCO (4) 55.8 (20.1, 88.1) 12.2 (0.4, 33.5) 31.9 (6.4, 64.1)
SCK (8) 53.3 (26.9, 80.7) 11.7 (0.7, 23.5) 35.0 (12.8, 57.9)
RP-81-1 Upland slough SCO (12) 45.3 (28.5, 64.9) 24.4 (11.9, 36.1) 30.2 (13.4, 48.8)
RP-81-3 Main channel SCK (3) 61.2 (23.0, 91.0) 17.8 (1.9, 40.6) 21.0 (0.9, 57.1)
RP-81-4 Side channel SCK (8) 40.0 (8.3, 78.5) 8.2 (0.1, 36.9) 51.7 (16.6, 85.3)
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Table 5.5-1. MANCOVA models testing for ontogenetic, temporal, and spatial differences in diet
composition. Degrees of freedom (df) are listed for both hypothesis (hyp) and error terms. Type-II p-values
are reported.
Factor Levels Hyp df Error df Wilk's
lambda F P
Arctic grayling (small; ≤ 120 mm FL)
Fork length (covariate) 50-120 mm 4 38 0.878 1.325 0.2784
Season Spring, Summer, Fall 8 76 0.525 3.609 0.0013
Focus Area RP-184, RP-173, RP-104, RP-81 12 101 0.492 2.587 0.0049
Habitat MC, SC, SS, TM 12 101 0.734 1.044 0.4154
Arctic grayling (large; > 120 mm FL)
Fork length (covariate) 124-394 mm 4 46 0.954 0.555 0.6963
Season Spring, Summer, Fall 8 92 0.612 3.206 0.0030
Focus Area RP-184, RP-173, RP-141, RP-104, RP-81 16 141 0.612 1.540 0.0937
Habitat MC, SC, TM 8 92 0.736 1.904 0.0686
Chinook Salmon
Fork length (covariate) 50-133 mm 5 181 0.995 0.181 0.9696
Year 2013, 2014 5 181 0.930 2.734 0.0208
Season Spring, Summer, Fall 10 362 0.745 5.736 <0.0001
Focus Area RP-184, RP-173, RP-141, RP-104, RP-81 20 601 0.841 1.612 0.0448
Habitat MC, SC, SS, TM, US 20 601 0.823 1.816 0.0163
Coho salmon
Fork length (covariate) 48-165 mm 5 233 0.795 11.996 <0.0001
Year 2013, 2014 5 233 0.895 5.494 <0.0001
Season Spring, Summer, Fall 10 466 0.751 7.179 <0.0001
Focus Area RP-141, RP-104, RP-81 10 466 0.851 3.906 <0.0001
Habitat MC, SC, SS, TM, US 20 774 0.769 3.189 <0.0001
Rainbow trout (large; > 120 mm FL)*
Fork length (covariate) 121-490 mm 5 30 0.865 0.933 0.4737
Season Spring, Summer, Fall 10 60 0.363 3.952 0.0004
Focus Area RP-141, RP-104, RP-81 10 60 0.345 4.212 0.0002
Habitat SS, TM, US 10 60 0.645 1.470 0.1731
*Note. Small rainbow trout (≤ 120 mm fork length) were not captured in sufficient numbers for statistical analysis (n
= 7 non-empty stomachs).
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Table 5.6-1. Overall summary of benthic organic matter components collected for 2013 sampling over three sampling events (Spring, Summer, Fall)
and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site
Macro-
habitat
Sampling
Device
Benthic CPOM (g/m2) Benthic FPOM (g/m2) Total Benthic OM (g/m2)
Range Average Median Range Average Median Range Average Median
RP-184 All 0 - 15.8 3.2 1.7 0 - 14 4.7 3.0 0.7 - 26.5 7.9 6.6
RP-184-1 TM Hess 0 - 13.1 2.4 0.9 0.2 - 8.7 3.1 2.7 0.7 - 16.5 5.6 5.1
RP-184-2 SC Hess 0 - 15.8 3 1.4 0 - 12.6 4.2 3.0 1.7 - 17.2 7.2 6.8
RP-184-3 MC Hess 0 - 14.2 4.2 2.7 0.3 - 14 6.6 7.9 1.8 - 26.5 10.8 7.9
RP-173 All 0 - 53 5.4 0.0 0 - 76.2 9.2 5.3 0 - 100.3 14.6 10.3
RP-173-1 TM Hess 0 - 28 8.9 8.5 0.5 - 24.5 7.3 6.5 3 - 38.4 16.2 13.9
RP-173-2 MC Hess 0 - 21.7 6.4 5.1 0.2 - 19.5 5.7 3.1 5.3 - 22.9 12.1 10.5
RP-173-3 SC Hess 0 - 8.2 1.7 0.0 0.5 - 14.9 4.5 3.2 2 - 14.9 6.2 5.2
RP-173-4 SS Hess & P. Ponar 0 - 53 5 0.0 0 - 76.2 13.4 7.0 0 - 100.3 18.4 12.3
RP-141 All 0 - 236.5 16.1 0.0 0.2 - 161.9 21.4 6.8 0.9 - 357.4 37.4 10.8
RP-141-1 TM Hess 0 - 24.8 4 0.0 0.2 - 12.7 4.6 3.8 1 - 27.8 8.6 7.0
RP-141-2 SC Hess & P. Ponar 0 - 120.9 12.7 0.0 1.9 - 73.3 13.3 6.2 1.9 - 150.7 25.9 13.1
RP-141-3 MC Hess 0 - 2 0.3 0.0 0.4 - 12.8 3.7 1.6 0.9 - 12.8 4.1 1.8
RP-141-4 US Hess & P. Ponar 0 - 236.5 33.4 2.6 1.2 - 161.9 44.9 37.2 4.1 - 357.4 78.3 52.1
RP-104 All 0 - 111.9 8.4 0.0 0 - 680.3 29.8 7.4 0.8 - 680.3 38.2 13.3
RP-104-1 TM/SS Hess 0 - 24.3 4.4 0.0 1.3 - 56.6 13.1 6.8 3.6 - 56.6 17.5 13.9
RP-104-2 SS Hess & P. Ponar 0 - 76.2 14.9 0.0 3 - 71 19.2 13.5 3.5 - 136.1 34.1 21.7
RP-104-3 MC Hess 0 - 111.9 12.2 2.4 0.3 - 32.6 8.6 2.6 2.1 - 117.5 20.8 10.0
RP-104-4 US P. Ponar 0 - 29.8 6.8 0.0 0.8 - 680.3 106.6 10.2 0.8 - 680.3 113.3 31.6
RP-104-5 SC Hess 0 - 4 0.8 0.0 0 - 21 6.5 3.4 1.1 - 21 7.3 4.6
RP-81 All 0 - 58 8.5 3.8 0.2 - 275.6 23.8 6.4 1.5 - 275.6 32.3 15.6
RP-81-1 US Hess & P. Ponar 0 - 58 14.2 14.1 5.8 - 275.6 74.1 46.9 22.7 - 275.6 88.2 60.3
RP-81-2 TM Hess 0 - 32.9 10 4.0 0.7 - 25.9 8.7 5.4 5.4 - 46.4 18.7 16.8
RP-81-3 MC Hess 0 - 24.9 7 4.6 0.4 - 40.1 7.7 1.7 3 - 40.1 14.8 15.0
RP-81-4 SC Hess 0 - 9.9 2.8 1.8 0.2 - 13.4 4.8 4.3 1.5 - 14 7.6 7.2
RP-TKA All 0 - 434.9 20.7 0.0 0.5 - 503.8 33.2 7.2 1 - 618.7 53.9 15.1
RP-TKA-1 SC Hess 0 - 27 4.1 0.0 0.5 - 15.3 4.6 3.7 1 - 28.9 8.6 5.5
RP-TKA-2 US P. Ponar 0 - 434.9 45.7 12.5 5.9 - 503.8 87.5 50.8 7.2 - 618.7 133.2 83.5
RP-TKA-3 SS Hess 0 - 99 12.4 0.0 1.4 - 20.9 7.4 5.5 1.7 - 101.8 19.9 13.4
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Table 5.6-2. Overall summary of drift (seston) organic matter components collected for 2013 sampling over three sampling events (Spring, Summer,
Fall) and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site Macrohabitat
Seston CPOM (mg/ft3) Seston FPOM (mg/ft3) Total Seston OM (mg/ft3)
Range Average Median Range Average Median Range Average Median
RP-184 All 0 - 3.5 1.34 1.42 0 - 16.4 1.83 0.83 0.08 - 16.4 3.18 2.99
RP-184-1 TM 0 - 3.5 1.56 1.68 0 - 2 0.51 0.11 0.08 - 3.7 2.07 2.44
RP-184-2 SC 0 - 3 1.27 1.06 0.4 - 1.6 0.98 0.95 0.81 - 4.6 2.25 1.58
RP-184-3* MC 0 - 2.4 1.2 1.36 0.55 - 16.4 4 1.71 1.36 - 16.4 5.20 3.16
RP-173 All 0 - 14.9 2.99 0.37 0.07 - 12.8 1.69 0.31 0.11 - 27.7 4.68 1.31
RP-173-1 TM 0 - 4 1.86 1.88 0.07 - 5.3 1.15 0.29 0.15 - 5.3 3.01 3.56
RP-173-2* MC 0 - 14.9 6.12 4.11 0.32 - 12.8 3.23 1.16 0.61 - 27.7 9.35 5.02
RP-173-3 SC 0 - 0 0 0.00 0.11 - 0.2 0.18 0.18 0.11 - 0.2 0.18 0.18
RP-173-4 SS –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-141 All 0 - 8.3 2.26 1.08 0.11 - 6.1 1.57 1.13 0.38 - 9.8 3.83 4.07
RP-141-1 TM 0 - 8.3 2.65 1.08 0.54 - 6.1 2.2 1.15 1.52 - 9.8 4.85 4.89
RP-141-2 SC 0.33 - 3.7 2.01 2.01 0.24 - 1.2 0.73 0.73 0.57 - 4.8 2.74 2.80
RP-141-3 MC 0 - 6.1 2.7 2.81 0.81 - 4.7 1.98 1.46 1.28 - 8.8 4.68 4.75
RP-141-4 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-141-5* MC, Above TM 0.21 - 0.3 0.26 0.26 0.11 - 0.2 0.14 0.14 0.38 - 0.4 0.4 0.40
RP-104 All 0 - 13.9 3.46 2.44 0 - 6.2 1.66 1.57 0 - 16 5.12 4.50
RP-104-1 TM/SS 0 - 7.5 1.59 0.00 0 - 0.1 0.07 0.08 0 - 7.6 1.66 0.09
RP-104-2* SS 4.81 - 13.9 9.38 9.38 1.73 - 2 1.87 1.87 6.53 - 16 11.24 11.24
RP-104-3 MC 0 - 8.3 3.82 3.68 0.48 - 6.2 3.07 3.07 0.69 - 13.2 6.88 6.92
RP-104-4 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-104-5 SC 1.08 - 4.4 2.78 2.79 1.05 - 2.6 1.83 1.85 2.13 - 6.4 4.61 4.94
RP-81 All 0 - 9.5 1.95 1.05 0.02 - 6.1 1.51 0.69 0.19 - 12.9 3.46 1.40
RP-81-1 US 0.15 - 0.2 0.18 0.18 0.03 - 0 0.04 0.04 0.19 - 0.2 0.21 0.21
RP-81-2 TM 0 - 1 0.46 0.42 0.33 - 0.7 0.46 0.38 0.68 - 1.3 0.92 0.83
RP-81-3 MC 0.25 - 9.5 2.58 1.14 0.27 - 3.4 1.49 0.75 0.52 - 12.9 4.08 1.88
RP-81-4 SC 0.17 - 6 2.91 3.27 0.02 - 6.1 2.66 2.90 0.19 - 12.1 5.57 6.53
RP-81-5* SC, Above TM 0.39 - 5.5 1.93 1.25 0.12 - 4.7 1.57 1.06 0.85 - 10.3 3.5 2.49
RP-TKA All 0 - 5.2 1.65 1.15 0.05 - 4.5 1.26 0.58 0.05 - 7.6 2.90 2.59
RP-TKA-1 SC 0 - 4.4 2.01 2.20 0.71 - 4.5 2.27 1.67 1.1 - 7.6 4.28 4.40
RP-TKA-2 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-TKA-3 SS 0 - 5.2 1.29 0.21 0.05 - 0.5 0.24 0.22 0.05 - 5.5 1.53 0.65
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Table 5.6-3. Overall summary of drift (seston) organic matter components collected for 2014 sampling over three sampling events (Spring, Summer,
Fall) and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site Macrohabitat
Seston CPOM (mg/ft3) Seston FPOM (mg/ft3) Total Seston OM (mg/ft3)
Range Average Median Range Average Median Range Average Median
RP-184 All 0.05 - 23.7 3.09 0.83 0.06 - 31 3.35 0.92 0.11 - 42.3 6.44 2.13
RP-184-1 TM 0.05 - 23.7 5.16 1.55 0.06 - 10.7 2.04 0.19 0.11 - 34.4 7.2 2.13
RP-184-2 SC 0.32 - 11.3 2.29 0.51 0.49 - 31 5.77 0.81 1.01 - 42.3 8.06 1.30
RP-184-3 MC 0.36 - 1.8 0.84 0.62 0.41 - 3.6 1.6 1.39 0.92 - 5.4 2.43 2.03
RP-184-4 MC, Above TM 0.85 - 9.3 4.07 3.86 0.46 - 17.7 3.99 1.18 1.75 - 27 8.07 4.86
RP-173 All 0.02 - 7.1 1.12 0.23 0.02 - 2.7 0.49 0.19 0.04 - 7.4 1.61 0.61
RP-173-1 TM 0.05 - 7.1 2.62 1.68 0.12 - 0.6 0.3 0.27 0.17 - 7.4 2.92 2.16
RP-173-2 MC 0.15 - 3.1 0.85 0.39 0.3 - 2.7 1.24 1.04 0.46 - 5.9 2.09 1.35
RP-173-3 SC 0.02 - 0.1 0.06 0.07 0.02 - 0.1 0.05 0.04 0.04 - 0.2 0.12 0.11
RP-173-4 SS –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-173-5* US 0.13 - 0.5 0.3 0.28 0.03 - 0.2 0.1 0.10 0.17 - 0.7 0.4 0.38
RP-141 All 0.08 - 9.2 1.51 0.61 0.16 - 23 2.13 0.54 0.25 - 32.2 3.64 1.35
RP-141-1 TM 0.2 - 1.6 0.95 0.98 0.19 - 0.6 0.37 0.32 0.47 - 2.1 1.32 1.35
RP-141-2 SC 0.08 - 9.2 4.26 3.90 0.16 - 23 8.53 5.47 0.25 - 32.2 12.79 9.37
RP-141-3 MC 0.19 - 0.7 0.44 0.52 0.22 - 2.1 0.93 0.50 0.43 - 2.8 1.37 0.95
RP-141-4 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-141-5 MC, Above TM 0.23 - 4.5 1.32 0.46 0.42 - 1.4 0.82 0.63 0.66 - 6 2.14 1.40
RP-104 All 0.06 - 4.1 1.35 0.93 0.18 - 4.9 1.51 1.17 0.63 - 8 2.87 2.10
RP-104-1 TM/SS 1.63 - 4.1 3.18 3.49 0.53 - 2.9 1.29 0.88 2.35 - 6.1 4.47 4.72
RP-104-2 SS –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-104-3 MC 0.3 - 0.9 0.71 0.75 0.83 - 1.8 1.27 1.26 1.13 - 2.5 1.99 2.10
RP-104-4 US 0.95 - 1 0.98 0.98 0.18 - 0.2 0.19 0.19 1.14 - 1.2 1.17 1.17
RP-104-5 SC 0.06 - 3.2 0.9 0.28 0.5 - 4.9 2.34 1.43 0.63 - 8 3.24 1.68
RP-81 All 0.1 - 2.1 0.76 0.55 0.06 - 2.6 0.76 0.43 0.28 - 4.3 1.52 1.08
RP-81-1 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-81-2 TM 0.15 - 2.1 0.9 0.67 0.22 - 2.6 1.11 0.86 0.38 - 4.3 2.01 1.53
RP-81-3 MC 0.27 - 2.1 1.01 0.95 0.23 - 0.8 0.37 0.28 0.71 - 2.4 1.39 1.23
RP-81-4 SC 0.1 - 1.1 0.46 0.34 0.1 - 2.4 0.87 0.43 0.28 - 3.5 1.32 0.77
RP-81-5 SC, Above TM 0.23 - 1.8 0.66 0.47 0.06 - 1.7 0.71 0.71 0.29 - 2.8 1.37 1.08
* Upland Slough located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 5.6-4. Summary of mean values of benthic organic matter components collected for 2013 sampling over three sampling events (Spring, Summer,
Fall) and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site
Macro-
habitat
Sampling
Device
Spring Summer Post Storm Fall
Benthic
CPOM
(g/m2)
Benthic
FPOM
(g/m2)
Total
Benthic
OM
(g/m2)
Benthic
CPOM
(g/m2)
Benthic
FPOM
(g/m2)
Total
Benthic
OM
(g/m2)
Benthic
CPOM
(g/m2)
Benthic
FPOM
(g/m2)
Total
Benthic
OM
(g/m2)
Benthic
CPOM
(g/m2)
Benthic
FPOM
(g/m2)
Total
Benthic
OM
(g/m2)
RP-184-1 TM Hess – – 5.49 4.88 3.58 8.46 – – – 2.37 0.39 2.76
RP-184-2 SC Hess – – 6.69 3.82 5.15 8.97 – – – 5.23 0.78 6.01
RP-184-3 MC Hess – – 8.18 9.74 10.98 20.72 – – – 2.97 0.67 3.64
RP-173-1 TM Hess – – 12.56 15.92 8.13 24.05 – – – 10.70 1.15 11.85
RP-173-2 MC Hess – – 12.34 9.03 4.01 13.03 – – – 10.14 0.69 10.83
RP-173-3 SC Hess – – 9.37 2.10 3.09 5.19 – – – 2.97 0.99 3.97
RP-173-4 SS Hess – – 9.35 5.46 3.82 9.28 7.17 6.85 14.02 8.69 1.68 10.37
RP-173-4 SS P. Ponar – – 26.33 0.89 15.31 16.20 14.51 34.31 48.82 5.62 2.66 8.27
RP-141-1 TM Hess – – 6.89 8.21 5.56 13.77 – – – 3.86 1.37 5.23
RP-141-2 SC Hess – – 25.72 30.41 11.32 41.73 – – – – – –
RP-141-2 SC P. Ponar – – – – – – – – – 7.58 2.78 10.36
RP-141-3 MC Hess – – 8.80 0.00 1.76 1.76 – – – 1.00 0.64 1.64
RP-141-4 US Hess – – 55.93 78.04 45.44 123.47 – – – 19.86 2.86 22.72
RP-141-4 US P. Ponar – – 53.97 55.19 40.88 96.07 – – – 50.73 53.81 104.54
RP-104-1 TM/SS Hess – – 25.17 0.55 10.75 11.30 – – – 12.73 3.38 16.11
RP-104-2 SS Hess – – 26.02 19.26 12.02 31.28 1.96 7.13 9.08 31.96 35.38 67.34
RP-104-2 SS P. Ponar – – – – – – – – – 31.17 9.87 41.05
RP-104-3 MC Hess – – 21.47 30.79 3.86 34.66 – – – 5.92 0.46 6.38
RP-104-4 US P. Ponar – – 295.61 6.54 20.80 27.34 – – – 13.83 3.25 17.08
RP-104-5 SC Hess – – 13.60 0.63 5.62 6.25 – – – 1.71 0.35 2.06
RP-81-1 US Hess – – – – – – – – – 24.47 10.54 35.00
RP-81-1 US P. Ponar – – 162.49 18.05 49.17 67.23 – – – – – –
RP-81-2 TM Hess – – 17.05 11.21 7.14 18.35 – – – 18.72 1.86 20.58
RP-81-3 MC Hess – – 20.63 4.41 1.58 5.99 – – – 16.71 0.96 17.68
RP-81-4 SC Hess – – 9.30 4.26 3.97 8.23 – – – 4.13 1.05 5.18
RP-TKA-1 SC Hess – – 9.26 0.00 3.14 3.14 – – – 12.16 1.35 13.51
RP-TKA-2 US P. Ponar – – 171.79 19.20 17.75 36.95 – – – 118.02 72.99 191.00
RP-TKA-3 SS Hess – – 12.11 2.08 3.28 5.36 – – – 35.22 6.94 42.16
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Table 5.6-5. Summary of mean values of drift (seston) organic matter components collected for 2013 sampling over three sampling events (Spring,
Summer, Fall) and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site Macrohabitat
Spring Summer Fall
Drift CPOM
(mg/ft3)
Drift FPOM
(mg/ft3)
Total Drift
OM
(mg/ft3)
Drift CPOM
(mg/ft3)
Drift FPOM
(mg/ft3)
Total Drift
OM (mg/ft3)
Drift
CPOM
(mg/ft3)
Drift FPOM
(mg/ft3)
Total Drift
OM
(mg/ft3)
RP-184-1 TM 0.00 0.08 0.08 2.11 1.38 3.48 2.58 0.07 2.66
RP-184-2 SC 2.74 1.35 4.09 0.00 1.11 1.11 1.06 0.49 1.55
RP-184-3* MC 1.58 0.70 2.27 0.00 9.60 9.60 2.02 1.71 3.74
RP-173-1 TM 1.70 0.12 1.82 0.23 3.04 3.26 3.66 0.29 3.95
RP-173-2* MC 10.49 2.24 12.72 7.47 7.07 14.54 0.40 0.37 0.78
RP-173-3 SC 0.00 0.18 0.18 0.00 0.18 0.18 –PK –PK –PK
RP-173-4 SS –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-141-1 TM 0.00 4.89 4.89 1.08 0.55 1.63 6.87 1.15 8.02
RP-141-2 SC 3.64 1.15 4.79 0.38 0.31 0.69 –PK –PK –PK
RP-141-3 MC 4.76 1.38 6.14 3.11 3.50 6.61 0.24 1.06 1.30
RP-141-4 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-141-5* MC, Above TM – – – 0.26 0.14 0.40 – – –
RP-104-1 TM/SS 0.00 0.05 0.05 0.00 0.06 0.06 4.77 0.09 4.86
RP-104-2* SS 9.38 1.87 11.24 –PK –PK –PK –PK –PK –PK
RP-104-3 MC 7.67 4.96 12.64 3.68 3.25 6.92 0.10 0.99 1.10
RP-104-4 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-104-5 SC 2.79 2.32 5.11 2.76 1.35 4.11 –PK –PK –PK
RP-81-1 US –PK –PK –PK –PK –PK –PK 0.18 0.04 0.21
RP-81-2 TM 0.16 0.54 0.70 – – – 0.76 0.38 1.13
RP-81-3 MC 6.27 3.25 9.52 1.14 0.74 1.88 0.35 0.48 0.83
RP-81-4 SC 4.71 4.30 9.01 3.81 3.64 7.46 0.21 0.03 0.24
RP-81-5* SC, Above TM 3.45 3.43 6.88 1.23 1.06 2.29 1.10 0.22 1.33
RP-TKA-1 SC 2.68 3.30 5.98 0.00 2.79 2.79 3.34 0.73 4.07
RP-TKA-2 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-TKA-3 SS 0.07 0.06 0.13 0.20 0.45 0.65 3.59 0.22 3.81
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Table 5.6-6. Summary of mean values of drift (seston) organic matter components collected for 2014 sampling over three sampling events (Spring,
Summer, Fall) and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site Macrohabitat
Spring Summer Fall
Drift CPOM
(mg/ft3)
Drift FPOM
(mg/ft3)
Total Drift
OM
(mg/ft3)
Drift CPOM
(mg/ft3)
Drift FPOM
(mg/ft3)
Total Drift
OM (mg/ft3)
Drift
CPOM
(mg/ft3)
Drift FPOM
(mg/ft3)
Total Drift
OM
(mg/ft3)
RP-184-1 TM 12.24 5.83 18.07 0.07 0.09 0.16 3.16 0.19 3.36
RP-184-2 SC 5.85 15.99 21.84 0.38 0.81 1.19 0.65 0.50 1.15
RP-184-3 MC 1.07 2.25 3.32 0.93 1.87 2.81 0.50 0.67 1.17
RP-184-4 MC, Above TM 6.90 10.29 17.19 0.98 1.18 2.15 4.35 0.51 4.86
RP-173-1 TM 1.68 0.48 2.16 0.09 0.14 0.22 6.10 0.28 6.38
RP-173-2 MC 2.02 2.36 4.37 0.32 1.04 1.35 0.23 0.33 0.56
RP-173-3 SC 0.10 0.08 0.18 0.03 0.03 0.05 –PK –PK –PK
RP-173-4 SS –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-173-5* US 0.47 0.16 0.62 0.13 0.04 0.17 –PK –PK –PK
RP-141-1 TM 1.08 0.56 1.64 0.30 0.32 0.63 1.47 0.21 1.68
RP-141-2 SC 3.49 4.50 8.00 5.03 12.55 17.58 –PK –PK –PK
RP-141-3 MC 0.20 0.36 0.56 0.67 1.96 2.63 0.44 0.47 0.91
RP-141-4 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-141-5 MC, Above TM 3.23 0.98 4.21 0.39 0.86 1.25 0.33 0.63 0.96
RP-104-1 TM/SS 3.49 1.70 5.20 –PK –PK –PK 2.88 0.88 3.75
RP-104-2 SS –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-104-3 MC 0.89 1.27 2.16 0.79 1.48 2.27 0.46 1.07 1.54
RP-104-4 US 0.98 0.19 1.17 –PK –PK –PK –PK –PK –PK
RP-104-5 SC 2.35 4.84 7.19 0.28 1.08 1.35 0.07 1.10 1.17
RP-81-1 US –PK –PK –PK –PK –PK –PK –PK –PK –PK
RP-81-2 TM 1.15 1.62 2.77 0.16 0.23 0.39 1.40 1.47 2.87
RP-81-3 MC 1.11 0.28 1.38 0.29 0.59 0.87 1.65 0.25 1.90
RP-81-4 SC 0.34 0.43 0.77 0.89 1.97 2.86 0.14 0.19 0.34
RP-81-5 SC, Above TM 0.45 0.07 0.51 0.38 1.28 1.66 1.14 0.79 1.93
* Upland Slough located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 5.8-1. Mean metric values (n=5) from Hess samples collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and
Upper River segments of the Susitna River for the River Productivity Study.
Tributary Name
Devil
Creek* Fog Creek
Deadman
Creek
Watana
Creek
Kosina
Creek Jay Creek
Oshetna
River Tyone River Butte Creek
Site ID RP-DEV-1 RP-FOG-1 RP-DED-1 RP-WAT-1 RP-KOS-1 RP-JAY-1 RP-OSH-1 RP-TYO-1 RP-BUT-1
Density (#/sq m) 8,428.52 9,519.66 132,347.55 28,273.53 5,176.73 20,364.24 1,360.47 21,730.36 7,266.15
Taxa Richness Mean (Total) 33.2 (55) 35.8 (63) 22.6 (39) 33.6 (58) 31.8 (55) 32.2 (59) 22 (45) 37.8 (64) 34.4 (61)
EPT Taxa Mean (Total) 8.8 (16) 10.4 (18) 3.2 (7) 8 (14) 8 (13) 6.4 (11) 6.6 (10) 6 (13) 9 (16)
Mayfly (E) Taxa Mean (Total) 4.8 (7) 5 (8) 2 (3) 4.6 (7) 5.2 (7) 4.4 (7) 4.8 (7) 2.4 (5) 5.6 (9)
Stonefly (P) Taxa Mean (Total) 2.8 (7) 4.6 (7) 0.8 (3) 2.8 (5) 1.8 (3) 1.2 (2) 1.8 (3) 0.6 (1) 2.6 (5)
Caddisfly (T) Taxa Mean (Total) 1.2 (2) 0.8 (3) 0.4 (1) 0.6 (2) 1 (3) 0.8 (2) 0 (0) 3 (7) 0.8 (2)
Chironomid Taxa Mean (Total) 16.2 (25) 17.6 (30) 14 (20) 16.6 (28) 16.8 (29) 16.2 (29) 10.6 (23) 19.8 (32) 17 (27)
Diversity (H') 2.83 2.94 2.17 2.80 2.57 2.72 2.56 2.80 2.88
Evenness (J') 0.81 0.82 0.70 0.80 0.75 0.79 0.84 0.77 0.82
Community Compositions
Percent Mayflies 12.75 13.45 3.29 15.32 17.52 12.64 35.86 1.66 13.68
Percent Stoneflies 5.60 9.48 0.31 5.78 1.37 3.53 11.39 0.26 2.01
Percent Caddisflies 0.70 0.45 0.13 0.25 0.84 0.38 0 4.06 0.32
Percent Chironomids 64.28 61.32 84.47 65.57 61.69 61.64 45.39 49.26 72.40
Percent Other Diptera 1.40 4.40 9.29 4.68 9.02 5.20 3.56 15.91 7.20
Percent Other Insects 0 0 0 0 0 0 0.16 0 0
Percent Non-insects 15.28 10.91 2.51 8.40 9.57 16.60 3.65 28.85 4.38
EPT:Chironomid Ratio 0.23 0.28 0.04 0.25 0.26 0.22 0.51 0.12 0.18
Percent Top Taxa 18.56 17.54 32.23 25.41 26.59 22.12 21.35 22.42 16.94
Percent Top 3 Taxa 42.16 38.21 62.18 44.94 52.46 46.90 48.02 46.15 39.08
Functional Feeding Groups (FFGs)
Percent Collector-Gatherers 79.37 75.04 62.23 75.57 71.96 81.46 56.87 38.23 84.60
Percent Collector-Filterers 1.40 3.32 16.56 2.68 9.26 1.04 1.92 21.73 6.43
Percent Scrapers 9.56 3.17 0.00 12.41 9.16 7.55 21.18 6.17 3.83
Percent Shredders 3.62 7.04 0.38 5.04 0.71 3.79 6.40 6.86 0.97
Percent Predators 4.82 4.78 3.59 3.93 3.50 5.12 13.15 12.74 3.91
Percent Parasites 1.03 3.47 0.18 0.31 3.82 0 0.38 8.91 0.20
Percent Other FFGs 0.19 3.17 17.06 0.06 1.59 1.04 0.10 5.37 0.07
* Site located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 5.8-2. Summary of benthic organic matter components collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and
Upper River segments of the Susitna River for the River Productivity Study.
Site Site ID
Sampling
Device
Benthic CPOM (g/m2) Benthic FPOM (g/m2) Total Benthic OM (g/m2)
Range Average Median Range Average Median Range Average Median
Butte Creek RP-BUT-1 Hess 0.57 - 3.7 1.91 0.97 0.44 - 2.6 1.57 1.55 1 - 6.3 3.48 2.71
Tyone River RP-TYO-1 Hess 5.93 - 10.8 8.24 7.29 4.02 - 16.3 9.39 8.70 9.95 - 23.6 17.63 19.26
Oshetna River RP-OSH-1 Hess 3.5 - 27.3 10.84 5.66 1.31 - 10.5 5.7 5.71 5.31 - 33 16.54 16.08
Jay Creek RP-JAY-1 Hess 6.57 - 41.1 16.69 8.28 3.75 - 32.3 10.47 5.21 11.78 - 73.3 27.16 14.53
Kosina Creek RP-KOS-1 Hess 1.04 - 11.6 5.23 3.05 0.2 - 3.1 1.31 0.66 1.24 - 14.7 6.54 3.83
Watana Creek RP-WAT-1 Hess 1.35 - 23.1 8.68 7.20 1.13 - 28.3 10.84 2.93 2.47 - 42.6 19.52 9.53
Deadman Creek RP-DED-1 Hess 2.88 - 73.8 26 18.57 2.14 - 9.2 4.84 2.96 9.8 - 83 30.84 21.50
Fog Creek RP-FOG-1 Hess 11.63 - 65.7 27.28 20.95 1.56 - 18.2 8.7 7.31 13.19 - 83.9 35.98 27.83
Devil Creek* RP-DEV-1* Hess 1.97 - 18.6 8.33 5.79 1.16 - 5.7 2.71 1.75 3.72 - 20.1 11.03 11.17
* Site located on Cook Inlet Regional Working Group (CIRWG) lands.
Table 5.8-3. Nutrient levels measured from water quality grab samples, and mean chlorophyll-a, pheophytin, and Ash Free Dry Mass (AFDM) values
(n=5) collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitn a River for the River
Productivity Study.
Tributary Name Site ID
Total
Phosphorus
(TP)
(µg/L)
Soluble
Reactive
Phosphorus
(SRP)
(µg/L)
Ammonia
as N
(µg/L)
Nitrate +
Nitrite
(NO3+NO2)
(µg/L)
Total Kjeldahl
Nitrogen
(TKN)
(mg/L)
Dissolved
Organic
Carbon
(DOC)
(mg/L)
Mean
Chlorophyll-a
(mg/m2)
Mean
Pheophytin
(mg/m2)
Mean
AFDM
(g/m2)
Butte Creek RP-BUT-1 2.9 <1 <10 19.8 <200 1.9 1.04 0.12 0.31
Tyone River RP-TYO-1 9.8 2.0 <10 <10 691 13.6 9.34 5.25 8.84
Oshetna River RP-OSH-1 56.7 2.4 <10 37.9 <200 1.0 0.14 0.04 0.10
Jay Creek RP-JAY-1 8.5 6.2 <10 36.7 <200 3.5 3.95 0.50 1.65
Kosina Creek RP-KOS-1 2.8 <1 <10 26.5 <200 1.2 0.44 0.46 0.40
Watana Creek RP-WAT-1 4.5 2.4 <10 30.0 <200 0.9 1.44 0.03 0.59
Deadman Creek RP-DED-1 6.2 2.8 <10 11.2 <200 2.1 14.82 6.50 27.69
Fog Creek RP-FOG-1 7.5 <1 <10 22.6 <200 1.0 3.51 6.40 1.85
Devil Creek* RP-DEV-1* 2.6 1.8 <10 48.7 <200 0.9 2.81 1.98 0.90
* Site located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 5.8-4. Mean metric values (n=2) from drift net samples collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and
Upper River segments of the Susitna River for the River Productivity Study.
Tributary Name
Devil
Creek* Fog Creek
Deadman
Creek
Watana
Creek
Kosina
Creek Jay Creek
Oshetna
River Tyone River Butte Creek
Site ID RP-DEV-1 RP-FOG-1 RP-DED-1 RP-WAT-1 RP-KOS-1 RP-JAY-1 RP-OSH-1 RP-TYO-1 RP-BUT-1
Density (#/cu. ft) 0.219 0.716 1.108 0.524 0.123 0.599 0.214 1.987 0.345
Taxa Richness Mean (Total) 37.5 (44) 45 (58) 34.5 (44) 46 (58) 49 (60) 48.5 (63) 40 (52) 14.5 (24) 36.5 (49)
EPT Taxa Mean (Total) 7 (8) 7 (10) 4 (4) 7.5 (9) 10.5 (14) 5.5 (7) 9 (10) 1 (1) 4.5 (6)
Mayfly (E) Taxa Mean (Total) 5.5 (6) 4 (6) 3 (3) 4.5 (5) 8 (9) 3.5 (5) 5.5 (6) 0 (0) 3.5 (5)
Stonefly (P) Taxa Mean (Total) 1 (1) 1.5 (2) 0 (0) 1.5 (2) 1.5 (3) 1 (1) 2 (2) 0 (0) 1 (1)
Caddisfly (T) Taxa Mean(Total) 0.5 (1) 1.5 (2) 1 (1) 1.5 (2) 1 (2) 1 (1) 1.5 (2) 1 (1) 0 (0)
Chironomid Taxa Mean (Total) 23 (26) 21.5 (25) 20 (24) 24.5 (31) 27.5 (33) 23 (28) 19.5 (26) 4 (7) 22.5 (31)
Zooplankton Taxa Mean (Total) 3 (4) 5 (8) 5.5 (8) 6.5 (8) 6 (7) 7.5 (10) 3.5 (5) 4 (8) 5 (6)
Non-insect Taxa Mean (Total) 0 (0) 2 (3) 0.5 (1) 1.5 (2) 0 (0) 3 (3) 2 (2) 3.5 (5) 1.5 (2)
Diversity (H') 3.01 3.02 2.79 3.19 3.46 3.11 2.83 1.60 2.64
Evenness (J') 0.83 0.79 0.79 0.83 0.89 0.80 0.77 0.60 0.73
Community Compositions
Percent Mayflies 12.89 13.99 9.94 4.39 13.95 2.73 27.32 0.00 6.55
Percent Stoneflies 0.43 0.76 0.00 1.57 0.48 2.13 1.51 0.00 0.30
Percent Caddisflies 0.15 0.55 0.28 0.47 0.48 0.43 0.59 3.80 0.00
Percent Chironomids 70.88 67.55 48.15 72.82 65.53 55.52 63.43 3.72 51.40
Percent Other Diptera 9.20 8.73 28.77 1.82 12.80 2.89 3.35 10.51 6.10
Percent Other Insects 1.13 2.24 0.88 0.78 0.31 1.64 0.92 0.32 0.15
Percent Zooplankton 0.00 2.08 1.34 5.03 0.00 3.61 1.08 78.60 1.04
Percent Non-insects 5.31 4.11 10.65 13.12 6.44 31.06 1.81 3.06 34.46
EPT:Chironomid Ratio 0.16 0.18 0.18 0.08 0.18 0.09 0.32 0.48 0.12
Percent Top Taxa 27.50 25.73 28.49 11.37 12.11 21.81 23.07 42.35 32.79
Percent Top 3 Taxa 39.52 46.47 50.15 31.84 27.72 43.67 54.86 86.70 54.43
* Site located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 5.8-5. Summary of drift (seston) organic matter components collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle
and Upper River segments of the Susitna River for the River Productivity Study.
Site Site ID Sampling
Device
Benthic CPOM (mg/ft3) Benthic FPOM (mg/ft3) Total Benthic OM (mg/ft3)
Range Average Median Range Average Median Range Average Median
Butte Creek RP-BUT-1 Drift Net 0.03 - 0.1 0.05 0.05 0.07 - 0.1 0.09 0.09 0.1 - 0.2 0.14 0.14
Tyone River RP-TYO-1 Drift Net 0.01 - 0.5 0.27 0.27 0.15 - 0.5 0.3 0.30 0.16 - 1 0.57 0.57
Oshetna River RP-OSH-1 Drift Net 0.32 - 0.8 0.55 0.55 0.39 - 0.8 0.61 0.61 0.7 - 1.6 1.16 1.16
Jay Creek RP-JAY-1 Drift Net 0.15 - 0.3 0.22 0.22 0.12 - 0.2 0.17 0.17 0.36 - 0.4 0.38 0.38
Kosina Creek RP-KOS-1 Drift Net 0.31 - 0.6 0.48 0.48 0.34 - 0.6 0.47 0.47 0.91 - 1 0.95 0.95
Watana Creek RP-WAT-1 Drift Net 0.08 - 0.1 0.11 0.11 0.2 - 0.3 0.22 0.22 0.33 - 0.3 0.33 0.33
Deadman Creek RP-DED-1 Drift Net 0.08 - 0.1 0.08 0.08 0.08 - 0.1 0.11 0.11 0.17 - 0.2 0.19 0.19
Fog Creek RP-FOG-1 Drift Net 0.36 - 0.9 0.65 0.65 0.31 - 0.5 0.41 0.41 0.67 - 1.4 1.05 1.05
Devil Creek* RP-DEV-1* Drift Net 0.05 - 0.1 0.08 0.08 0.05 - 0.1 0.05 0.05 0.1 - 0.2 0.13 0.13
* Site located on Cook Inlet Regional Working Group (CIRWG) lands.
Table 5.8-6. In-situ water quality measurements collected in July 2014 at sites in nine tributaries above Devils Canyon in the Middle and Upper River
segments of the Susitna River for the River Productivity Study.
Tributary Name Site ID
Temperature
(°C)
Specific
Conductance
(µS/cm)
General
Conductance
(µS) pH
Dissolved
Oxygen, DO
(mg/L)
Percent
Dissolved
Oxygen
Redox
Potential, ORP
(mv)
Turbidity
(NTU)
Butte Creek RP-BUT-1 7.1 130 86 6.9 12.7 104.9 173.1 0.2
Tyone River RP-TYO-1 16.8 309 260 8.6 11.7 120.6 137.9 8.3
Oshetna River RP-OSH-1 6.2 128 82 6.5 13.6 109.7 159 16.1
Jay Creek RP-JAY-1 8.2 118 80 7.1 11.3 95.5 103.1 0.6
Kosina Creek RP-KOS-1 7.4 52 35 6.3 11.9 100 137.1 0.4
Watana Creek RP-WAT-1 8.8 76 52 6.5 9.6 82.8 137 0.4
Deadman Creek RP-DED-1 11.5 95 70 7.4 10.7 98.2 157.7 3.6
Fog Creek RP-FOG-1 8.1 92 62 7.4 12.3 103.5 125.2 1.3
Devil Creek* RP-DEV-1* 9.5 64 45 6.2 10.6 92.7 187.8 0
* Site located on Cook Inlet Regional Working Group (CIRWG) lands.
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Table 5.8-7. Mean metric values (n=5) from petite Ponar grab samples collected in July 2014 for sites within three lakes in the Upper River Segment of
the Susitna River for the River Productivity Study.
Lake Name Tyone Lake (RP-LTY) Susitna Lake (RP-LSU) Lake Louise (RP-LLO)
Site ID RP-LTY-1 RP-LTY-2 RP-LTY-3 RP-LSU-1 RP-LSU-2 RP-LSU-3 RP-LLO-1 RP-LLO-2 RP-LLO-3
Depth (ft) 4.5 16.5 21 78 22 90 107 133 17
Density (#/sq m) 1,119.45 4,055.84 7,550.52 75.35 6,096.68 667.36 930.00 1,102.22 1,455.28
Taxa Richness Mean (Total) 10.2 (24) 12.2 (25) 13.2 (21) 1 (1) 15.2 (26) 4.8 (8) 4 (6) 5.8 (11) 13.2 (30)
EPT Taxa Mean (Total) 2 (3) 0 0 0 0.2 (1) 0 0 0 0.2 (1)
Mayfly (E) Taxa Mean (Total) 0.8 (1) 0 0 0 0 0 0 0 0
Stonefly (P) Taxa Mean (Total) 0 0 0 0 0 0 0 0 0
Caddisfly (T) Taxa Mean (Total) 0.6 (2) 0 0 0 0.2 (1) 0 0 0 0.2 (1)
Chironomid Taxa Mean (Total) 4.4 (12) 7.8 (17) 7.2 (12) 0 9 (17) 1.2 (3) 1 (2) 2.2 (7) 8 (17)
Diversity (H') 1.91 2.00 1.99 0 1.93 1.36 1.12 1.33 2.27
Evenness (J') 0.92 0.88 0.77 0 0.72 0.88 0.83 0.76 0.94
Community Compositions
Percent Mayflies 8.56 0 0 0 0 0 0 0 0
Percent Stoneflies 0.00 0 0 0 0 0 0 0 0
Percent Caddisflies 1.93 0 0 0 0.16 0 0 0 0.44
Percent Chironomids 41.52 49.18 31.68 0 23.60 8.54 5.68 10.15 65.71
Percent Other Diptera 0 0 0 0 0 0 0 0 1.64
Percent Other Insects 0 0 0 0 0 0 0 0 0
Percent Non-insects 47.99 50.82 68.32 100.00 76.24 91.46 94.32 89.85 32.20
EPT:Chironomid Ratio 0.18 0 0 0 0.01 0 0 0 0.01
Percent Top Taxa 33.58 32.75 36.65 100.00 45.28 41.62 50.23 48.76 27.78
Percent Top 3 Taxa 65.59 67.75 65.48 100.00 69.33 84.16 93.58 86.86 59.62
Functional Feeding Groups (FFGs)
Percent Collector-Gatherers 63.06 47.34 43.71 100.00 27.51 34.46 45.67 80.58 37.49
Percent Collector-Filterers 10.48 6.15 4.96 0 9.45 22.68 27.16 6.78 28.69
Percent Scrapers 0.62 6.07 7.19 0 10.89 0 0.77 1.60 1.76
Percent Shredders 0.31 1.35 0.42 0 1.10 0 0 0 3.38
Percent Predators 9.22 9.81 6.70 0 4.21 4.89 4.91 2.31 23.36
Percent Parasites 14.38 29.28 37.02 0 46.77 37.97 21.49 8.72 4.46
Percent Other FFGs 1.93 0 0 0 0.07 0 0 0 0.85
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Table 5.8-8. Summary of benthic organic matter components from petite Ponar samples (n=5) collected in July 2014 for sites within three lakes in the
Upper River Segment of the Susitna River for the River Productivity Study.
Site Site ID Sampling
Device
Benthic CPOM (g/m2) Benthic FPOM (g/m2) Total Benthic OM (g/m2)
Range Average Median Range Average Median Range Average Median
Tyone Lake RP-LTY P. Ponar 0.08 - 107.2 29.9 17.52 9 - 116.7 56.79 43.92 10.1 - 208.8 86.69 83.17
Tyone Lake - Lower RP-LTY-1 P. Ponar 45.2 - 107.2 68.29 57.26 43.9 - 101.6 75.69 68.89 101.2 - 208.8 143.98 115.82
Tyone Lake - Middle RP-LTY-2 P. Ponar 0.08 - 46.9 20.09 17.52 40.9 - 116.7 78.85 83.10 55.8 - 163.6 98.94 83.17
Tyone Lake - Upper RP-LTY-3 P. Ponar 0.71 - 2.5 1.32 1.10 9 - 26.8 15.83 11.32 10.1 - 29.3 17.15 12.59
Susitna Lake RP-LSU P. Ponar 0.09 - 9.3 2.72 1.42 10.63 - 90.8 33.89 28.59 11.16 - 99.9 36.61 31.87
Susitna Lake - Lower RP-LSU-1 P. Ponar 0.43 - 2.4 1.42 1.42 11.63 - 50.8 28.41 32.08 14.01 - 52.2 29.82 33.98
Susitna Lake - Middle RP-LSU-2 P. Ponar 3.28 - 9.3 6.46 6.03 28.59 - 90.8 58.68 44.78 31.87 - 99.9 65.14 49.51
Susitna Lake - Upper RP-LSU-3 P. Ponar 0.09 - 0.5 0.27 0.24 10.63 - 18.9 14.6 13.22 11.16 - 19.2 14.87 13.30
Lake Louise RP-LLO P. Ponar 0 - 45.6 11.41 0.80 4.26 - 389.2 101.41 30.91 4.41 - 424.8 112.82 30.91
Lake Louise - Lower RP-LLO-1 P. Ponar 0.13 - 1.2 0.67 0.80 4.26 - 27.4 15.09 14.25 4.41 - 28.2 15.76 15.31
Lake Louise - Middle RP-LLO-2 P. Ponar 0 - 0.8 0.17 0.00 25.62 - 39.4 32.87 30.91 25.67 - 40.2 33.04 30.91
Lake Louise - Upper RP-LLO-3 P. Ponar 15.5 - 45.6 33.39 35.61 174.4 - 389.2 256.27 197.63 189.9 - 424.8 289.65 240.25
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Table 5.8-9. Metric values from qualitative shoreline benthic D-net sweep samples collected in July 2014 for sites within three lakes in the Upper River
Segment of the Susitna River for the River Productivity Study.
Lake Name Tyone Lake (RP-LTY) Susitna Lake (RP-LSU) Lake Louise (RP-LLO)
Site ID RP-LTY-1 RP-LTY-2 RP-LTY-3 RP-LSU-1 RP-LSU-2 RP-LSU-3 RP-LLO-1 RP-LLO-2 RP-LLO-3
Taxa Richness 30 34 37 39 24 33 26 32 32
EPT Taxa 1 4 5 3 1 5 3 7 4
Mayfly (E) Taxa 1 2 2 1 0 1 1 1 1
Stonefly (P) Taxa 0 0 1 2 0 1 1 3 1
Caddisfly (T) Taxa 0 2 2 0 1 3 1 3 2
Chironomid Taxa 15 13 17 17 10 13 9 13 9
Diversity (H') 1.90 2.66 2.86 2.93 1.84 2.80 2.54 2.59 2.41
Evenness (J') 0.56 0.76 0.79 0.80 0.58 0.80 0.78 0.75 0.70
Community Compositions
Percent Mayflies 0.66 1.62 3.96 6.10 0.00 7.07 11.65 31.21 29.01
Percent Stoneflies 0.00 0.00 3.96 11.89 0.00 0.32 0.32 3.50 4.14
Percent Caddisflies 0.00 0.65 0.99 0.00 0.33 3.54 0.32 2.55 0.55
Percent Chironomids 72.09 18.51 17.49 28.35 6.89 18.97 42.72 29.94 10.22
Percent Other Diptera 0.00 0.32 0.99 2.13 0.66 1.29 0.32 0.96 1.10
Percent Beetles 0.33 0.00 0.66 1.83 0.98 0.64 3.56 4.46 0.83
Percent Non-insects 26.58 78.57 71.62 49.39 91.15 58.84 41.10 27.39 53.87
EPT:Chironomid Ratio 0.01 0.11 0.34 0.39 0.05 0.37 0.22 0.55 0.77
Percent Top Taxa 57.74 22.40 26.43 25.91 49.18 13.50 17.15 31.21 29.01
Percent Top 3 Taxa 69.42 50.16 41.28 40.69 69.18 35.69 43.69 49.36 59.94
Functional Feeding Groups (FFGs)
Percent Collector-Gatherers 78.91 45.70 66.27 67.53 74.75 57.56 54.37 67.52 59.39
Percent Collector-Filterers 0.66 4.35 1.65 1.83 0.66 0.64 0.97 0.00 2.49
Percent Scrapers 8.64 38.96 4.62 1.22 19.67 19.94 15.86 6.37 25.14
Percent Shredders 5.04 3.76 5.94 13.13 1.97 5.14 12.62 3.18 5.52
Percent Predators 6.09 4.96 18.55 9.16 1.64 14.47 10.03 18.47 5.25
Percent Parasites 0.66 2.27 2.97 4.27 0.98 1.29 6.15 3.82 1.93
Percent Other FFGs 0.00 0.00 0.00 2.87 0.33 0.96 0.00 0.64 0.28
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Table 5.8-10. Mean metric values (n=5) from plankton tow samples collected in July 2014 for sites within three lakes in the Upper River Segment of the
Susitna River for the River Productivity Study. Density and biomass estimates are areal (per m2) as opposed to by volume.
Lake Name Tyone Lake (RP-LTY) Susitna Lake (RP-LSU) Lake Louise (RP-LLO)
Site ID RP-LTY-1 RP-LTY-2 RP-LTY-3 RP-LSU-1 RP-LSU-2 RP-LSU-3 RP-LLO-1 RP-LLO-2 RP-LLO-3
Density (#/m2) 47,513.0 185,087.0 215,180.2 192,272.8 127,312.6 93,342.1 21,576.2 253,697.4 75,365.1
Biomass (mg/m2) 149.11 553.37 487.32 481.49 311.30 214.18 243.11 498.81 202.41
Taxa Richness Mean (Total) 5 (6) 4.6 (5) 4.8 (5) 4 (4) 4.4 (5) 4.4 (6) 2.8 (4) 3.6 (6) 4.2 (5)
Cladocera Taxa Mean (Total) 3 (4) 2.6 (3) 2.8 (3) 2 (2) 2.4 (3) 2.4 (4) 0.8 (2) 1.6 (4) 2.2 (3)
Copepod Taxa Mean (Total) 2 (2) 2 (2) 2 (2) 2 (2) 2 (2) 2 (2) 2 (2) 2 (2) 2 (2)
Community Compositions by Density (percent)
Eubosmina longispina 1.91 0.74 3.57 1.51 1.23 1.98 0.87 1.93 1.33
Daphnia longiremis 9.95 18.11 5.91 3.13 2.49 0.96 0.18 0.10 5.45
Daphnia ambigua 2.64 6.05 1.97 0.00 0.55 0.29 0.00 0.00 0.41
Other Cladocera 0.26 0.00 0.00 0.00 0.00 0.12 0.00 0.26 0.00
Copepoda - nauplii 17.63 33.30 44.67 27.48 45.49 33.93 26.33 28.88 6.90
Copepoda - Calanoida 26.50 17.29 16.27 17.93 28.21 14.28 9.10 14.64 40.42
Copepoda - Cyclopoida 41.10 24.52 27.62 49.95 22.02 48.44 63.52 54.18 45.49
Community Compositions by Weight (percent)
Eubosmina longispina 1.61 1.33 6.88 3.38 2.35 4.43 2.02 3.86 2.69
Daphnia longiremis 11.93 24.65 9.30 9.55 3.63 3.90 0.27 0.52 11.52
Daphnia ambigua 3.63 9.51 4.21 0.00 0.97 1.32 0.00 0.00 0.45
Other Cladocera 0.22 0.00 0.00 0.00 0.00 1.28 0.00 1.56 0.00
Copepoda - nauplii 5.16 10.46 17.39 9.86 16.79 13.44 11.83 13.06 2.27
Copepoda - Calanoida 42.71 32.88 30.80 30.76 54.33 28.29 21.02 21.87 43.32
Copepoda - Cyclopoida 34.74 21.16 31.43 46.44 21.92 47.34 64.87 59.13 39.76
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Table 5.8-11. Mean Secchi depths, light extinction coefficients, and calculated euphotic zone depths for sites
within three lakes in the Upper River Segment of the Susitna River for the River Productivity Study in July
2014.
Site Site ID WaterDepth (ft)
Average Secchi
Depth (ft)
Light Extinction
Coefficient
Calculated
Euphotic Zone
Depth (ft)
Tyone Lake - Lower RP-LTY-1 4.5 Visible to bottom 0.2731 16.9
Tyone Lake - Middle RP-LTY-2 16.5 12.5 0.2291 20.1
Tyone Lake - Upper RP-LTY-3 21 14.25 0.2011 22.9
Susitna Lake - Lower RP-LSU-1 78 18.55 0.1054 43.7
Susitna Lake - Middle RP-LSU-2 22 18.75 0.1436 32.1
Susitna Lake - Upper RP-LSU-3 90 21.5 0.0982 46.9
Lake Louise - Lower RP-LLO-1 107 27 0.1069 43.1
Lake Louise - Middle RP-LLO-2 133 24.75 0.1025 44.9
Lake Louise - Upper RP-LLO-3 17 Visible to bottom 0.1101 41.8
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Table 5.8-12. Nutrient and chlorophyll-a levels measured from water quality grab samples collected near surface, near euphotic depth, and near-
bottom in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the River Productivity Study.
Site ID Replicate
Water Grab
Depth (ft)
Total
Phosphorus
(TP)
(µg/L)
Soluble
Reactive
Phosphorus
(SRP)
(µg/L)
Ammonia as
N
(µg/L)
Nitrate +
Nitrite
(NO3+NO2)
(µg/L)
Total
Kjeldahl
Nitrogen
(TKN)
(mg/L)
Dissolved
Organic
Carbon (DOC)
(mg/L)
Alkalinity
(mg/L)
Mean
Chlorophyll-
a
(µg/L)
Mean
Pheophytin
(µg/L)
RP-LTY-1 1 2 7.2 1.4 <10 <10 434.9 10.4 54.6 2.1 <0.3
RP-LTY-2 1 2 6.5 1.2 <10 <10 398.7 9.7 56.4 1.6 <0.3
RP-LTY-2 2 15 11.5 1.9 11.5 <10 519.3 10.2 56.3 1.1 1.9
RP-LTY-3 1 2 7.1 <1 <10 <10 400.4 8.9 58.2 2.0 0.8
RP-LTY-3 2 18 9.3 2.0 52.5 <10 437.8 9.5 58.6 2.7 0.3
RP-LSU-1 1 6 6.7 <1 <10 <10 429.1 7.9 60.5 2.7 <0.3
RP-LSU-1 2 36 4.6 <1 <10 <10 330.0 7.7 61.5 3.7 <0.3
RP-LSU-1 3 75 11.2 1.3 138.0 52.9 475.1 7.5 67.1 <0.3 2.4
RP-LSU-2 1 2 6.1 1.3 <10 <10 455.4 8.5 60.0 1.1 1.2
RP-LSU-2 2 20 5.9 <1 <10 <10 378.6 9.1 60.8 <0.3 4.5
RP-LSU-3 1 6 5.4 1.2 <10 <10 409.8 7.9 60.5 1.1 2.7
RP-LSU-3 2 36 5.3 1.5 10.5 <10 361.3 7.6 61.7 <0.3 9.3
RP-LSU-3 3 87 5.5 <1 21.7 16.5 426.7 7.4 62.0 1.1 3.4
PR-LLO-1 1 6 6.3 <1 <10 <10 353.0 8.2 62.5 2.1 4.2
PR-LLO-1 2 33 7.0 1.9 <10 <10 620.5 7.5 62.9 1.1 3.8
PR-LLO-1 3 95 9.8 3.7 11.2 11.2 374.5 7.1 63.3 4.8 <0.3
RP-LLO-2 1 6 6.1 2.9 <10 <10 325.0 7.5 62.4 <0.3 <0.3
RP-LLO-2 2 42 8.1 2.7 <10 <10 350.6 7.4 63.0 1.1 <0.3
RP-LLO-2 3 129 15.1 7.9 15.7 12.5 381.0 8.3 63.9 1.6 <0.3
PR-LLO-3 1 2 6.0 1.0 <10 <10 362.1 7.5 62.8 2.1 <0.3
PR-LLO-3 2 16 6.3 1.8 <10 <10 345.6 7.7 62.1 <0.3 <0.3
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Table 6.6-1: Comparison of river site water quality with Alaska standards and other typical measurements in
the region.
Parameter Alaska State Water
Quality Standard
Range of
Values for 9
Tributary
Study Sites
Comparison
Average Range Source
Temperature (ºC)
<15ºC for migration
routes/spawning
areas; <13ºC for
Spawning
areas/Incubation
6.2-16.8 – 4-20 Davis and Davis 2008
DO (mg/L) <5 mg/L 9.6-13.6 – – –
pH >6.5, <8.5 6.3-8.6 7.9 6.7-8.8 Tanana Basin Study
(Moran, 2007)
Specific
Conductivity
(μS/cm)
– 52-309 228.6 12-1323 Tanana Basin Study
(Moran 2007)
Total Phosphorus
(μg/L) <1001 2.7-57 – 50-150 Cook Inlet Studies,(Brabets
et al. 1999)
Ammonium (μg/L) NA <10 240 150-340 Tanana Basin Study
(Moran 2007)
Nitrate-Nitrite
(μg/L) 10,000 <10-49 100 10-1000 Cook Inlet Studies (Glass
et al. 2004)
Dissolved
Organic Carbon
(mg/L)
NA 0.85-13.6 4.3 0.3-4.3;
0.5-18
Tanana Basin Study
(Moran 2007); Cook Inlet
Studies (Glass et al. 2004)
Turbidity (NTU)
May not exceed 25
NTU above natural
conditions
0.2-8.3 – – –
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Table 6.6-2. Comparison of lake site water quality with other lakes in the region.
Parameter
Typical
Oligotrophic
Lake Values1
Range of Values for
9 Lake Study Sites
Cook Inlet Basin Lake Survey2
Average Range
Temperature (ºC) 5.3-16.2 10.8 4.2-18.9
DO (mg/L) 0.11-10.5 8.4 1.1-12
pH 6.9-8.5 7.6 3.8-10.2
Conductivity (μS/cm) 155.7-765.4 89 7.5-670
Secchi (meters) >8-4 3.7-8.2 3.7 0.6-8.5
Total Phosphorus (μg/L) 0-12 <2-15.2 24.1 10-32.3
Ammonia-N (μg/L) <10 - 138 10.2 1.4-51
Nitrate-Nitrite (μg/L) <10 - 53 44.8 0.8-476
TOC, Dissolved (mg/L) 7.1-10.4 5.3 0.5-19.5
Alkalinity (mg/L) 54.6-67.1 44 11-105
Chlorophyll A (μg/L) 0-2.6 <0.3-4.8 6.6 0.18-13.1
1 Carlson and Simpson 1996.
2 ADEC 2008.
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10. FIGURES
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Figure 3-1. Middle Susitna River Segment, with the four River Productivity sampling stations /Instream Flow Focus Areas selected f or the River
Productivity Study, plus the sampling station for reference sites on the Talkeetna River.
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Figure 3-2. Lower Susitna River Segment, with Montana Creek area River Productivity sampling station selected for the River Productivity Study.
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Figure 3-3. Tributary sites and lake sites above Devils Canyon in the Middle and Upper Segments, selected for the 2014 River Productivity Study.
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Figure 3-4. Lake sites above Devils Canyon in the Middle and Upper Segments, selected for the 2014 River
Productivity Study.
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Figure 4.2-1. Focus Area 184 (Watana Dam), and the three River Productivity sampling sites.
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Figure 4.2-2. Focus Area FA-173 (Stephan Lake Complex), and the four River Productivity sampling sites. Site RP-173-3, originally identified as a side
channel, has been reclassified as a side slough by the Aquatic Habitat Study (Study 9.9) in 2014.
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Figure 4.2-3. Focus Area FA-141 (Indian River), and the four River Productivity sampling sites.
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Figure 4.2-4. Focus Area FA-104 (Whiskers Slough), and the five River Productivity sampling sites.
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Figure 4.2-5. Station RP-81 (Montana Creek), and the four River Productivity sampling sites.
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Figure 4.3-1. Size distribution of the 155 snag pieces collected in 2013 during the open water season within
the all sites the Susitna River for the River Productivity Study.
Distribution of Woody Debris Sizes
Diameter Size Range (inches)
0-1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10Number of Woody Debris Pieces0
10
20
30
40
50
60
70
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Figure 4.6-1. Sampling equipment used to collect benthic macroinvertebrates in streams and rivers Top left:
Hess stream sampler. Top right: drift nets. Bottom left: floating aquatic insect emergence trap. Bottom
right: D-net kick sampler.
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Figure 4.10-1. Sampling equipment used to collect invertebrates and water quality samples from lakes. Top
left: Petite Ponar grab sampler. Top right: plankton net. Bottom left: PAR meter and in situ YSI multiprobe
water quality meter. Bottom right: Van Dorn vertical water sampler.
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Figure 5.1-1. Mean emergence trap density estimates (n=1) collected in 2013 during the open water season
within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the Susitna River for the River
Productivity Study. Bar width indicates the length of period deployment for the emergence trap. “N/A”
indicates no sample was collected during that time period.
RP-184-1 TM
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
5
10
15
20
25
30 RP-184-3 MC
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
50
100
150
200
250
N/A
Ephemeroptera Plecoptera Trichoptera
Coleoptera Chironomidae Other Diptera
Hymenoptera Hemiptera Others
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Figure 5.1-2. Mean emergence trap density estimates (n=1) collected in 2013 during the open water season
within the Stephan Lake complex Focus Area (FA-173) in the Middle River Segment of the Susitna River for
the River Productivity Study. Bar width indicates the length of period deployment for the emergence trap.
“N/A” indicates no sample was collected during that time period.
RP-173-1 TM
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50 RP-173-2 MC
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
RP-173-3 SC
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
RP-173-4 SS
Date
Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
N/A
N/A N/A
N/A
N/A
Ephemeroptera Plecoptera Trichoptera
Coleoptera Chironomidae Other Diptera
Hymenoptera Hemiptera Others
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Figure 5.1-3. Mean emergence trap density estimates (n=1) collected in 2013 during the open water season
within the Indian River Focus Area (FA-141) in the Middle River Segment of the Susitna River for the River
Productivity Study. Bar width indicates the length of period deployment for the emergence trap. “N/A”
indicates no sample was collected during that time period.
RP-141-1 TM
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
50
100
150
200
250
300 RP-141-2 SC
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
60
RP-141-3 MC
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
60
RP-141-4 US
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
60
N/A N/A
N/A N/A N/A
N/A
N/A
Ephemeroptera Plecoptera Trichoptera
Coleoptera Chironomidae Other Diptera
Hymenoptera Hemiptera Others
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Figure 5.1-4. Mean emergence trap density estimates (n=1) collected in 2013 during the open water season
within the Whiskers Slough Focus Area (FA-104) in the Middle River Segment of the Susitna River for the
River Productivity Study. Bar width indicates the length of period deployment for the emergence trap.
“N/A” indicates no sample was collected during that time period.
RP-104-1 TM/SS
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50 RP-104-2 SS
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
RP-104-3 MC
Date
Jun Jul Aug Sep Oct Emergence Abundance (number/m2/day)0
10
20
30
40
50
RP-104-4 US
Date
Jun Jul Aug Sep Oct Emergence Abundance (number/m2/day)0
20
40
60
80
100
120
140
160
180
RP-104-5 SC
Date
Jun Jul Aug Sep Oct Emergence Abundance (number/m2/day)0
10
20
30
40
50
N/A
N/A N/A
Ephemeroptera Plecoptera Trichoptera
Coleoptera Chironomidae Other Diptera
Hymenoptera Hemiptera Others
Ephemeroptera Plecoptera Trichoptera
Coleoptera Chironomidae Other Diptera
Hymenoptera Hemiptera Others
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Figure 5.1-5. Mean emergence trap density estimates (n=1) collected in 2013 during the open water season
within the Montana Creek study area (RP-81) in the Lower River Segment of the Susitna River for the River
Productivity Study. Bar width indicates the length of period deployment for the emergence trap. “N/A”
indicates no sample was collected during that time period.
RP-81-1 US
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50 RP-81-2 TM
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
RP-81-3 MC
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
RP-81-4 SC
Date
Jun Jul Aug Sep Emergence Abundance (number/m2/day)0
10
20
30
40
50
N/A N/A
N/A
N/A N/A
Ephemeroptera Plecoptera Trichoptera
Coleoptera Chironomidae Other Diptera
Hymenoptera Hemiptera Others
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Figure 5.1-6. Mean density estimates collected from woody debris in 2013 during three sampling events for
sites within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no sample
was collected.
Figure 5.1-7. Mean taxa richness estimates collected from woody debris in 2013 during three sampling events
for sites within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the Susitna River for
the River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no
sample was collected.
RP- 184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean Density (Individuals/m2)0
2000
4000
6000
8000
10000
12000
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel
N/AN/A N/A N/AN/A
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean Number of Taxa Collected0
5
10
15
20
25
30
35
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel
N/AN/A N/A N/AN/A
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Figure 5.1-8. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates collected from
woody debris in 2013 during three sampling events for sites within the Watana Dam Focus Area (FA-184) in
the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. “N/A” indicates no sample was collected.
Figure 5.1-9. Mean density estimates collected from woody debris in 2013 during three sampling events for
sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A”
indicates no sample was collected.
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean Number of EPT Taxa Collected0
2
4
6
8
10
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel
N/AN/A N/A N/AN/A
RP- 173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4Mean Density (Individuals/m2)0
2000
4000
6000
8000
10000
12000
Spring
Summer
Fall
Trib Mouth Side SloughMain Channel Side Channel
N/A N/AN/A N/AN/A
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Figure 5.1-10. Mean taxa richness estimates collected from woody debris in 2013 during three sampling
events for sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle River Segment of the
Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A”
indicates no sample was collected.
Figure 5.1-11. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates collected from
woody debris in 2013 during three sampling events for sites within the Stephan Lake Complex Focus Area
(FA-173) in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals. “N/A” indicates no sample was collected.
RP-173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4Mean Number of Taxa Collected0
5
10
15
20
25
Spring
Summer
Fall
Trib Mouth Main Channel Side Channel Side Slough
N/A N/AN/A N/AN/A
RP- 173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4Mean Number of EPT Taxa Collected0
1
2
3
4
5
6
Spring
Summer
Fall
Trib Mouth Main Channel Side Channel Side Slough
N/A N/AN/A N/AN/A
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Figure 5.1-12. Mean density estimates collected from woody debris in 2013 during three sampling events for
sites within the Indian River Focus Area (FA-141) in the Middle River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no sample
was collected.
Figure 5.1-13. Mean taxa richness estimates collected from woody debris in 2013 during three sampling
events for sites within the Indian River Focus Area (FA-141) in the Middle River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A”
indicates no sample was collected.
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4Mean Density (Individuals/m2)0
5000
10000
15000
20000
25000
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel
N/A N/A N/AN/A
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4Mean Number of Taxa Collected0
5
10
15
20
25
30
35
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel
N/A N/A N/AN/A
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Figure 5.1-14. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates collected from
woody debris in 2013 during three sampling events for sites within the Indian River Focus Area (FA-141) in
the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. “N/A” indicates no sample was collected.
Figure 5.1-15. Mean density estimates collected from woody debris in 2013 during three sampling events for
sites within the Whiskers Slough Focus Area (FA-104) in the Middle River Segment of the Susitna River for
the River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no
sample was collected.
RP- 141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4Mean Number of EPT Taxa Collected0
2
4
6
8
10
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel
N/A N/A N/AN/A
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5Mean Density (Individuals/m2)0
2000
4000
6000
8000
10000
12000
Spring
Summer
Fall
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
N/A N/AN/A N/A
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Figure 5.1-16. Mean taxa richness estimates collected from woody debris in 2013 during three sampling
events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A”
indicates no sample was collected.
Figure 5.1-17. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates collected from
woody debris in 2013 during three sampling events for sites within the Whiskers slough Focus Area (FA-104)
in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. “N/A” indicates no sample was collected.
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5Mean Number of Taxa Collected0
10
20
30
40
Spring
Summer
Fall
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
N/A N/AN/A N/A
RP- 104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5Mean Number of EPT Taxa Collected0
1
2
3
4
5
6
7
Spring
Summer
Fall
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
N/A N/AN/A N/A
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Figure 5.1-18. Mean density estimates collected from woody debris in 2013 during three sampling events for
sites within the Montana Creek Study Area (RP-81 in the Lower River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A” indicates no sample
was collected. “0” indicates zero organisms were collected on collected woody debris.
Figure 5.1-19. Mean taxa richness estimates collected from woody debris in 2013 during three sampling
events for sites within the Montana Creek Study Area (RP-81) in the Lower River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals. “N/A”
indicates no sample was collected. “0” indicates zero organisms were collected on collected woody debris.
RP-81 (Montana Creek)
Station / Site
RP-81-1 RP-81-2 RP-81-3 RP-81-4Mean Density (Individuals/m2)0
2000
4000
6000
8000
10000
Spring
Summer
Fall
Trib Mouth Main ChannelUpland Slough Side Channel
N/A0
RP-81 (Montana Creek)
Station / Site
RP-81-1 RP-81-2 RP-81-3 RP-81-4Mean Number of Taxa Collected0
5
10
15
20
25
30
Spring
Summer
Fall
Trib Mouth Main ChannelUpland Slough Side Channel
N/A0
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Figure 5.1-20. Mean EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates collected from
woody debris in 2013 during three sampling events for sites within the Montana Creek Study Area (RP -81) in
the Lower River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. “N/A” indicates no sample was collected. “0” indicates zero organisms were
collected on collected woody debris.
Figure 5.2-1. Mean drift density estimates from drift samples (n=2) collected in 2014 during three sampling
events for sites within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP- 81 (Montana Creek)
Station / Site
RP-81-1 RP-81-2 RP-81-3 RP-81-4Mean Number of EPT Taxa Collected0
2
4
6
8
10
Spring
Summer
Fall
Trib Mouth Main ChannelUpland Slough Side Channel
N/A0
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3 RP-184-4Mean Density (Individuals/ft3)0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.56.0
6.5
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel Above Trib Mouth
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Figure 5.2-2. Mean drift taxa richness estimates from drift samples (n=2) collected in 2014 during three
sampling events for sites within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the
Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 5.2-3. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5) collected in 2014
during three sampling events for sites within the Stephan Lake Complex Focus Area (FA-173) in the Middle
River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. Bars marked with a “P” are plankton tows.
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3 RP-184-4Mean Number of Taxa Collected0
10
20
30
40
50
60
70
Spring
Summer
Fall
Trib Mouth Main ChannelSide Channel Above Trib Mouth
RP-173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4 Tow RP-173-5Mean Density (Individuals/ft3)0
2
4
6
8
10
1240
60
80
100
120
Spring
Summer
Fall
Trib Mouth Side SloughMain Channel Side Channel
P
P
P
P P
Upland Slough
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Figure 5.2-4. Mean drift taxa richness estimates from drift samples (n=2) and plankton tows (n=5) collected
in 2014 during three sampling events for sites within the Stephan Lake Complex Focus Area (FA -173) in the
Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals. Bars marked with a “P” are plankton tows.
Figure 5.2-5. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5) collected in 2014
during three sampling events for sites within the Indian River Focus Area (FA-141) in the Middle River
Trib Mouth Side SloughMain Channel Side Channel Upland Slough
RP-173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4 Tow RP-173-5Mean Number of Taxa Collected0
10
20
30
40
50
60
70
Spring
Summer
Fall
P
P P
P
P
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 Tow RP-141-5Mean Density (Individuals/ft3)0
1
2
3
4
5
6
7
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel Main Channel
Above Trib
P
P
P
P
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Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. Bars marked with a “P” are plankton tows.
Figure 5.2-6. Mean drift taxa richness estimates from drift samples (n=2) and plankton tows (n=5) collected
in 2014 during three sampling events for sites within the Indian River Focus Area (FA-141) in the Middle
River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. Bars marked with a “P” are plankton tows.
Figure 5.2-7. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5) collected in 2014
during three sampling events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 Tow RP-141-5Mean Number of Taxa Collected0
10
20
30
40
50
60
Spring
Summer
Fall
Trib Mouth Main Channel Upland SloughSide Channel Main Channel
Above Trib
P
P P P
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2.1 Tow RP-104-2 Tow RP-104-3 RP-104-4 Tow RP-104-5Mean Density (Individuals/ft3)0
2
4
6
8
1040
60
80
100
Spring
Summer
Fall
Trib Mouth Side Slough
Above Trib
Main Channel Upland Slough Side Channel
P
P
P
P
P
Side Slough
N/A
P
P P
P
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Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. Bars marked with a “P” are plankton tows. “N/A” - no samples were collected.
Figure 5.2-8. Mean drift taxa richness estimates from drift samples (n=2) and plankton tows (n=5) collected
in 2014 during three sampling events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle
River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. Bars marked with a “P” are plankton tows. “N/A” - no samples were collected.
Figure 5.2-9. Mean drift density estimates from drift samples (n=2) and plankton tows (n=5) collected in 2014
during three sampling events for sites within the Montana Creek area (RP-81) in the Lower River Segment of
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2.1 Tow RP-104-2 Tow RP-104-3 RP-104-4 Tow RP-104-5Mean Number of Taxa Collected0
10
20
30
40
50
Spring
Summer
Fall
Trib Mouth Side Slough
Above Trib
Main Channel Upland Slough Side ChannelSide Slough
P
P
PP
P
N/A
P
P P
P
RP- 81 (Montana Creek)
Station / Site
RP-81-1 Tow RP-81-2 RP-81-3 RP-81-4 RP-81-5Mean Density (Individuals/ft3)0.00
0.25
0.50
0.75
1.00
1.25
1.50
10.00
20.00
30.00
40.00
50.00
Spring
Summer
Fall
Trib Mouth Main ChannelUpland Slough Side Channel Side Channel
Above Trib Mouth
P P
P
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the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Bars marked with a “P” are plankton tows.
Figure 5.2-10. Mean drift taxa richness estimates from drift samples (n=2) and plankton tows (n=5) collected
in 2014 during three sampling events for sites within the Montana Creek area (RP-81) in the Lower River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. Bars marked with a “P” are plankton tows.
RP- 81 (Montana Creek)
Station / Site
RP-81-1 Tow RP-81-2 RP-81-3 RP-81-4 RP-81-5Mean Number of Taxa Collected0
10
20
30
40
50
60
70
Spring
Summer
Fall
P
P
P
Trib Mouth Main ChannelUpland Slough Side Channel Side Channel
Above Trib Mouth
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Figure 5.4-1. Length-frequency distributions of Chinook Salmon and Coho Salmon sampled during June
2013 and June 2014 in the study area of the River Productivity Study by the Fish Distribution and
Abundance in the Middle and Lower River Study. Distributions are truncated at 60 mm fork length to show
size structure of age-0 fish.
0.0
2.5
5.0
7.5
10.0
0
20
40
60 2013201430 35 40 45 50 55 60
For k length (mm)FrequencyChinook and Coho length frequency dur ing June
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Figure 5.4-2. Seasonal length-at-age relationship of Chinook Salmon collected during 2013 and aged from
scales.
0
2
4
6
0
1
2
3
0
1
2
3 SpringSummerFall60 70 80 90 100 110 120 130 140
Fork length (mm)FrequencyChinook
Age
0
1
2
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Figure 5.4-3. Seasonal length-at-age relationship of Coho Salmon collected during 2013 and aged from scales.
0
2
4
6
0.0
2.5
5.0
7.5
10.0
12.5
0
2
4
6 SpringSummerFall50 70 90 110 130 150 170
Fork length (mm)FrequencyCoho Ag e
0
1
2
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Figure 5.4-4. Seasonal length-at-age relationship of Rainbow Trout collected during 2013 and aged from
scales.
0.0
0.5
1.0
1.5
2.0
0.0
0.5
1.0
1.5
2.0
0.00
0.25
0.50
0.75
1.00 SpringSummerFall50 100 150 200 250 300
For k length (mm)FrequencyRainbow
Age
0
1
2
3
4
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Figure 5.4-5. Seasonal length-at-age relationship of Chinook Salmon aged from scales during 2014.
0
2
4
6
0
5
10
15
0
5
10 SpringSummerFall50 60 70 80 90 100 110
For k length (mm)FrequencyChinook
Age
0
1
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Figure 5.4-6. Seasonal length-at-age relationship of Coho Salmon aged from scales during 2014.
0
1
2
3
4
5
0
3
6
9
0.0
2.5
5.0
7.5
10.0
12.5 SpringSummerFall50 70 90 110 130
Fork length (mm)FrequencyCoho Ag e
0
1
2
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Figure 5.4-7. Seasonal length-at-age relationship of Arctic Grayling aged from scales during 2014.
0.0
2.5
5.0
7.5
10.0
12.5
0.0
2.5
5.0
7.5
10.0
0
5
10 SpringSummerFall50 100 150 200 250 300 350 400
For k length (mm)FrequencyGrayling
Age
0
1
2
3
4
5
6
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Figure 5.4-8. Seasonal length-at-age relationship of Rainbow Trout aged from scales during 2014.
0.0
0.5
1.0
1.5
2.0
0
1
2
3
4
0.0
0.5
1.0
1.5
2.0 SpringSummerFall50 100 150 200 250 300 350 400 450 500
Fork length (mm)FrequencyRainbow
Age
0
2
3
4
5
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Figure 5.4-9. Seasonal mean weights of age-0 Chinook Salmon sampled in main channel and side channel
habitats (main/side channel) and side sloughs, tributary mouths, and upland slough habitats (off-channel)
during 2013 and 2014. Symbols represent means ± 1 SE. The mean weight of age-0 Chinook Salmon during
spring of each year was estimated from length-frequency distributions and a length-weight relationship, and
these values are reported for all habitats combined, without error.
●
●
●
●
●●
0
2
4
6
8
Spring Summer Fall
SeasonWeight (g)Year and Habitat
●
●
2013 Off−channel
2014 Main/side channel
2014 Off−channel
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Figure 5.4-10. Seasonal mean weights of age-0 Coho Salmon sampled in all habitats (side channel, side
slough, tributary mouth, and upland slough) during 2013 and 2014. Symbols represent means ± 1 SE. The
mean weight of age-0 Coho Salmon during spring of each year was estimated from length-frequency
distributions and a length-weight relationship, and these values are reported without error.
●
●
●
0
1
2
3
4
Spring Summer Fall
SeasonWeight (g)Year
●
2013
2014
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Figure 5.4-11. Seasonal mean weights of age-1 Coho Salmon sampled in side channel and tributary mouth
habitats (SC / TM) and side sloughs and upland slough habitats (SS / US) during 2013 and 2014. Symbols
represent means ± 1 SE.
●
●
●
●
●
2
4
6
8
10
12
14
Spring Summer Fall
SeasonWeight (g)Year and Habitat
●
●
2013 SC / TM
2013 SS / US
2014 SC / TM
2014 SS / US
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Figure 5.4-12. Daily mean stream temperatures recorded at all study sites during 2013 and 2014.
0
5
10
15
Jun Jul Aug Sep Oct
DateTemperature (°C)Year
2013
2014
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Figure 5.4-13. Daily mean stream temperatures recorded at each site in 2013, displayed by macrohabitat type
(top panel); daily stream temperatures averaged across all sites within each habitat type (bottom panel).
0
5
10
15
Jun Jul Aug Sep Oct
DateTemperature (°C)Habitat
Main channel
Side channel
Side slough
Trib mouth
Upland slough
4
8
12
16
Jun Jul Aug Sep Oct
DateTemperature (°C)Habitat
Main channel
Side channel
Side slough
Trib mouth
Upland slough
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Figure 5.4-14. Daily mean stream temperatures recorded at each site in 2014, displayed by macrohabitat type
(top panel); daily stream temperatures averaged across all sites within each macrohabitat type (bottom
panel).
0
5
10
15
Jun Jul Aug Sep Oct
DateTemperature (°C)Habitat
Main channel
Side channel
Side slough
Trib mouth
Upland slough
0
5
10
15
Jun Jul Aug Sep Oct
DateTemperature (°C)Habitat
Main channel
Side channel
Side slough
Trib mouth
Upland slough
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Figure 5.4-15. Daily mean stream temperatures recorded at each site in 2014 (gray); sites where the stomach
contents of juvenile salmon contained salmon eggs are plotted in black.
0
5
10
15
Jun Jul Aug Sep Oct
DateTemperature (°C)
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Figure 5.4-16. Associations between temperature, drift invertebrate biomass density, flow velocity, turbidity
and model-estimated growth rate potential of drift feeding age-1 Coho Salmon.
−0.02
−0.01
0.00
0.01
0.02
0.03
0.04
0 1 2 3 4 5 6
Drift Inver tebrate Biomass Density
(mg dr y / m^2 / sec)Growth rate potential (g / g / day)−0.02
−0.01
0.00
0.01
0.02
0.03
0.04
2 4 6 8 10 12 14 16
Temperature (°C)Growth rate potential (g / g / day)−0.02
−0.01
0.00
0.01
0.02
0.03
0.04
0 100 200 300 400 500 600
Turbidity (NTU)Growth rate potential (g / g / day)Habitat
Main channel
Side channel
Side slough
Trib mouth
−0.02
−0.01
0.00
0.01
0.02
0.03
0.04
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Flow velocity (m / sec)Growth rate potential (g / g / day)
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Figure 5.4-17. Monthly length frequency distributions of Chinook Salmon and Coho Salmon sampled in the
Middle and Lower Susitna River during 2013 and 2014.
0.00
0.01
0.02
0.03
0.00
0.01
0.02
0.03
0.00
0.01
0.02
0.03
0.00
0.01
0.02
0.03
0.000
0.005
0.010
0.015
0.020
0.025
0.00
0.02
0.04
0.06
0.000
0.005
0.010
0.015
0.020
0.00
0.01
0.02
0.03
0.000
0.005
0.010
0.015
0.020 FebMarAprMayJunJulAugSepOct20 40 60 80 100 120 140 160 180 200
Fork length (mm)DensityYear
2013
2014
Chinook and Coho length−frequency b y year :
Lower and Middle Susitna Riv er
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Figure 5.4-18. Comparisons of the mean dietary proportions of juvenile Chinook and Coho salmon across
sampling periods in 2013, as determined by Bayesian stable isotope mixing models before genetic analysis of
juvenile salmon tissues (Pre) and after the incorporation of species reassignments and informative priors
from stomach contents (Post).
Overall proportion of diet0.0
0.2
0.4
0.6
0.8
1.0
Chinook SalmonSpring
P ost0.0
0.2
0.4
0.6
0.8
1.0
Coho SalmonFreshwater Marine Terrestrial
PreSummer
P ostPreFall
P ostPre
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Figure 5.4-19. Comparisons of the mean dietary proportions of juvenile Chinook and Coho salmon across
macrohabitats in 2013, as determined by Bayesian stable isotope mixing models before genetic analysis of
juvenile salmon tissues (Pre) and after the incorporation of species reassignments and informative priors
from stomach contents (Post).
0.0
0.2
0.4
0.6
0.8
1.0
Chinook Salmon0.0
0.2
0.4
0.6
0.8
1.0
Coho SalmonOverall proportion of dietSide slough
P ostPreUpland slough
P ostPreTributary mouth
P ostPreSide channel
P ostPreFreshwater Marine Terrestrial
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Figure 5.4-20. Comparisons of the mean dietary proportions of juvenile Chinook and Coho salmon across RP
Focus Areas in 2013, as determined by Bayesian stable isotope mixing models before genetic analysis of
juvenile salmon tissues (Pre) and after the incorporation of species reassignments and informative priors
from stomach contents (Post).
0.0
0.2
0.4
0.6
0.8
1.0
Chinook Salmon0.0
0.2
0.4
0.6
0.8
1.0
Coho SalmonOverall proportion of dietFA 81
P ostPreFA 104
P ostPreFA 141
P ostPreFreshwater Marine Terrestrial
RP -81 RP -104 RP -141
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Figure 5.4-21. Median 13C values (with 2.5, 25, 75, 97.5% ranges; open circles represent values outside the
distribution) for organic matter, algae, and aquatic invertebrates pooled by macrohabitat type.
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Figure 5.4-22. Median 13C values (with 2.5, 25, 75, 97.5% ranges; open circles represent values outside the
distribution) for organic matter, algae, and aquatic invertebrates pooled by reach (Focus Area).
Station
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Figure 5.4-23. Median 13C values (with 2.5, 25, 75, 97.5% ranges; open circles represent values outside the
distribution) for organic matter, algae, and aquatic invertebrates pooled by season.
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Figure 5.4-24. Linear regressions of aquatic invertebrate consumer group 13C against potential food source
(periphyton [filled circles] and terrestrial organic matter [open circles]) 13C for 2014. Each data point
represents site-specific mean invertebrate 13C vs. site-specific mean source 13C for all seasons combined.
-40
-35
-30
-25
-20
-40
-35
-30
-25
-20
-40 -35 -30 -25 -20
-40
-35
-30
-25
-20
Source d13C
1:1 line
Collector d13C Grazer d13C Shredder d13C
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Figure 5.4-25. Diet composition of juvenile Chinook Salmon in 2014, as estimated with MixSIAR Bayesian
mixing models. Box plots show the mean proportional contribution (with 2.5, 25, 75, and 97.5 credibility
intervals) of each prey category to the diet. Contributions of all diet sources from a single sampling event are
stacked vertically across panels. Model results are grouped so that all spatial and temporal dietary trends
addressed in this study may be discerned: first by macrohabitat as indicated by labels at the bottom of the
plot, then by season as indicated by panel color and labels at the top of the plot (SP = spring, SU = summer,
FA = fall), and lastly by increasing distance from the river mouth as indicated by box color (see legend).
RP-81 RP-104 RP-141 RP-184
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Figure 5.4-26. Diet composition of juvenile Coho Salmon in 2014, as estimated with MixSIAR Bayesian
mixing models. Box plots show the mean proportional contribution (with 2.5, 25, 75, and 97.5 credibility
intervals) of each prey category to the diet. Contributions of all diet sources from a single sampling event are
stacked vertically across panels. Model results are grouped so that all spatial and temporal dietary trends
addressed in this study may be discerned: first by macrohabitat as indicated by labels at the bottom of the
plot, then by season as indicated by panel color and labels at the top of the plot (SP = spring, SU = summer,
FA = fall), and lastly by increasing distance from the river mouth as indicated by box color (see legend).
RP-81 RP-104 RP-141 RP-184
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Figure 5.4-27. Diet composition of Arctic Grayling in 2014, as estimated with MixSIAR Bayesian mixing
models. Box plots show the mean proportional contribution (with 2.5, 25, 75, and 97.5 credibility intervals) of
each prey category to the diet. Contributions of all diet sources from a single sampling event are stacked
vertically across panels. Model results are grouped so that all spatial and temporal dietary trends addressed
in this study may be discerned: first by macrohabitat as indicated by labels at the bottom of the plot, then by
season as indicated by panel color and labels at the top of the plot (SP = spring, SU = summer, FA = fall), and
lastly by increasing distance from the river mouth as indicated by box color (see legend).
RP-81 RP-104 RP-141 RP-184
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Figure 5.4-28. Diet composition of resident salmonids (GRA: Arctic Grayling; TRB: Rainbow Trout) in 2014,
as estimated with MixSIAR Bayesian mixing models. Boxplots show the mean proportional contribution
(with 2.5, 25, 75, and 97.5 credibility intervals) of each prey category to the diet. Contributions of all diet
sources from a single sampling event are stacked vertically across panels. Model results are grouped by
season.
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Figure 5.5-1. Overall diet composition of two size classes of Arctic Grayling (GRA), juvenile Chinook Salmon
(SCK), juvenile Coho Salmon (SCO), and two size classes of Rainbow Trout (TRB) sampled during 2013 and
2014 in the Susitna River. Size classes were defined as small (SM; ≤ 120 mm fork length [FL]) and large (LG;
> 120 mm FL). Diet proportions (by dry mass) were determined by stomach content analysis. Prey items
were categorized as aquatic life-stages of freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-stages
of freshwater invertebrates (FW inv. [Ter LS]), terrestrial invertebrates (Ter. inv.), fish and non-salmonid
fish eggs (Fish & non-sm. eggs), or salmon eggs.
0.00
0.25
0.50
0.75
1.00
GRA
(SM)
GRA
(LG)
SCK SCO TRB
(SM)
TRB
(LG)
Species and size classDiet proportion by weightPrey Categor y
FW inv. (Aqu. LS)
FW inv. (Ter. LS)
Ter. inv.
Fish & non−sm. eggs
Salmon eggs
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Figure 5.5-2. Annual and seasonal patterns of diet composition of juvenile Chinook Salmon (SCK) and
juvenile Coho Salmon (SCO) sampled during 2013 and 2014 in the Susitna River. Diet proportions (by dry
mass) were determined by stomach content analysis. Seasons are abbreviated as spring (Spr), summer
(Sum), and fall (Fal). Prey items were categorized as aquatic life-stages of freshwater invertebrates (FW inv.
[Aqu LS]), terrestrial life-stages of freshwater invertebrates (FW inv. [Ter LS]), terrestrial invertebrates
(Ter. inv.), fish and non-salmonid fish eggs (Fish & non-sm. eggs), or salmon eggs.
2013 2014
0.00
0.25
0.50
0.75
1.00
0.00
0.25
0.50
0.75
1.00 SCKSCOSpr Sum Fal Spr Sum Fal
SeasonDiet proportion by weightPrey Categor y
Aqu. inv.
Ter. inv. (Aqu. org.)
Ter. inv. (Ter. org.)
Fish & non−sm. eggs
Salmon eggs
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Figure 5.5-3. Proportion (by dry mass) of salmon eggs in the stomach contents of individual Chinook Salmon,
Coho Salmon, and Rainbow Trout sampled by gastric lavage, as a function of fork length. Figure is
truncated at 150 mm fork length to show detail at smaller lengths. Only fish captured during sampling
events when salmon eggs were available for consumption are shown. These sampling events were determined
by the presence of salmon eggs in the stomach contents of at least one sampled fish.
0.00
0.25
0.50
0.75
1.00
40 50 60 70 80 90 100 110 120 130 140 150
For k length (mm)Proportion salmon eggs in diet (by mass)Species
Chinook
Coho
Rainbow
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Figure 5.5-4. Proportion (by dry mass) of fish in the stomach contents of individual Arctic Grayling, Chinook
Salmon, Coho Salmon, and Rainbow Trout sampled by gastric lavage, as a function of fork length.
0.00
0.25
0.50
0.75
1.00
50 100 150 200 250 300 350 400 450 500
For k length (mm)Proportion fish in diet (by mass)Species
Grayling
Chinook
Coho
Rainbow
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Figure 5.5-5. Seasonal diet composition of two size classes of Arctic Grayling (GRA) sampled during 2014
and two size classes of Rainbow Trout (TRB) sampled during 2013 and 2014 in the Susitna River. Size classes
were defined as small (SM; ≤ 120 mm fork length [FL]) and large (LG; > 120 mm FL). Diet proportions (by
dry mass) were determined by stomach content analysis. Prey items were categorized as aquatic life-stages of
freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-stages of freshwater invertebrates (FW inv. [Ter
LS]), terrestrial invertebrates (Ter. inv.), fish and non-salmonid fish eggs (Fish & non-sm. eggs), or salmon
eggs.
SM LG
0.00
0.25
0.50
0.75
1.00
0.00
0.25
0.50
0.75
1.00 GRATRBSpr Sum Fal Spr Sum Fal
SeasonDiet proportion by weightPrey Categor y
Aqu. inv.
Ter. inv. (Aqu. org.)
Ter. inv. (Ter. org.)
Fish & non−sm. eggs
Salmon eggs
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Figure 5.5-6. Large-scale spatial patterns of diet composition of two size classes of Arctic Grayling (GRA)
sampled during 2014 and two size classes of Rainbow Trout (TRB) sampled during 2013 and 2014 in the
Susitna River. Fish were sampled in five study stations (RP-184, RP-173, RP-141, RP-104, and RP-81), which
were abbreviated in the x-axis labels by project river mile. Size classes were defined as small (SM; ≤ 120 mm
fork length [FL]) and large (LG; > 120 mm FL). Diet proportions (by dry mass) were determined by stomach
content analysis. Prey items were categorized as aquatic life-stages of freshwater invertebrates (FW inv.
[Aqu LS]), terrestrial life-stages of freshwater invertebrates (FW inv. [Ter LS]), terrestrial invertebrates
(Ter. inv.), fish and non-salmonid fish eggs (Fish & non-sm. eggs), or salmon eggs.
SM LG
0.00
0.25
0.50
0.75
1.00
0.00
0.25
0.50
0.75
1.00 GRATRB184 173 141 104 81 184 173 141 104 81
StationDiet proportion by weightPrey Categor y
FW inv. (Aqu. LS)
FW inv. (Ter. LS)
Ter. inv.
Fish & non−sm. eggs
Salmon eggs
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Figure 5.5-7. Habitat-based patterns of diet composition of two size classes of Arctic Grayling (GRA)
sampled during 2014 and two size classes of Rainbow Trout (TRB) sampled during 2013 and 2014 in the
Susitna River. Fish were sampled in five macrohabitat types: main channel (MC), side channel (SC), side
slough (SS), tributary mouth (TM), and upland slough (US). Size classes were defined as small (SM; ≤ 120
mm fork length [FL]) and large (LG; > 120 mm FL). Diet proportions (by dry mass) were determined by
stomach content analysis. Prey items were categorized as aquatic life-stages of freshwater invertebrates (FW
inv. [Aqu LS]), terrestrial life-stages of freshwater invertebrates (FW inv. [Ter LS]), terrestrial invertebrates
(Ter. inv.), fish and non-salmonid fish eggs (Fish & non-sm. eggs), or salmon eggs.
SM LG
0.00
0.25
0.50
0.75
1.00
0.00
0.25
0.50
0.75
1.00 GRATRBMC SC SS TM US MC SC SS TM US
HabitatDiet proportion by weightPrey Categor y
Aqu. inv.
Ter. inv. (Aqu. org.)
Ter. inv. (Ter. org.)
Fish & non−sm. eggs
Salmon eggs
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Figure 5.5-8. Large-scale spatial patterns of diet composition of juvenile Chinook Salmon (SCK) and juvenile
Coho Salmon (SCO) sampled during 2013 and 2014 in the Susitna River. Fish were sampled in five study
stations (RP-184, RP-173, RP-141, RP-104, and RP-81), which were abbreviated in the x-axis labels by
project river mile. Size classes were defined as small (SM; ≤ 120 mm fork length [FL]) and large (LG; > 120
mm FL). Diet proportions (by dry mass) were determined by stomach content analysis. Prey items were
categorized as aquatic life-stages of freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-stages of
freshwater invertebrates (FW inv. [Ter LS]), terrestrial invertebrates (Ter. inv.), fish and non-salmonid fish
eggs (Fish & non-sm. eggs), or salmon eggs.
2013 2014
0.00
0.25
0.50
0.75
1.00
0.00
0.25
0.50
0.75
1.00 SCKSCO184 173 141 104 81 184 173 141 104 81
StationDiet proportion by weightPrey Categor y
FW inv. (Aqu. LS)
FW inv. (Ter. LS)
Ter. inv.
Fish & non−sm. eggs
Salmon eggs
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Figure 5.5-9. Habitat-based patterns of diet composition of juvenile Chinook Salmon (SCK) and juvenile
Coho Salmon (SCO) sampled during 2013 and 2014 in the Susitna River. Fish were sampled in five
macrohabitat types: main channel (MC), side channel (SC), side slough (SS), tributary mouth (TM), and
upland slough (US). Size classes were defined as small (SM; ≤ 120 mm fork length [FL]) and large (LG; > 120
mm FL). Diet proportions (by dry mass) were determined by stomach content analysis. Prey items were
categorized as aquatic life-stages of freshwater invertebrates (FW inv. [Aqu LS]), terrestrial life-stages of
freshwater invertebrates (FW inv. [Ter LS]), terrestrial invertebrates (Ter. inv.), fish and non-salmonid fish
eggs (Fish & non-sm. eggs), or salmon eggs.
2013 2014
0.00
0.25
0.50
0.75
1.00
0.00
0.25
0.50
0.75
1.00 SCKSCOMC SC SS TM US MC SC SS TM US
HabitatDiet proportion by weightPrey Categor y
Aqu. inv.
Ter. inv. (Aqu. org.)
Ter. inv. (Ter. org.)
Fish & non−sm. eggs
Salmon eggs
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Figure 5.6-1. Mean benthic organic matter estimates (g/m2) from Hess samples collected in 2013 during three
sampling events for sites within the Watana Dam Focus Area (FA-184) in the Middle River Segment of the
Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 5.6-2. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2013
during three sampling events for sites within the Watana Dam Focus Area (FA-184) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals.
RP- 184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean AFDM Organic Matter (g/m2)0
5
10
15
20
25
30
Spring
Summer
Fall
FPOM
Trib Mouth Main ChannelSide Channel
2013 Benthic OM
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean AFDM Organic Matter (mg/ft3)0
2
4
6
8
10
20
25
Spring
Summer
Fall
FPOM
Trib Mouth Main ChannelSide Channel
2013 Drift OM
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Figure 5.6-3. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2014
during three sampling events for sites within the Watana Dam Focus Area (FA-184) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals.
Figure 5.6-4. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab samples
collected in 2013 during three sampling events for sites within the Stephan Lake Complex Focus Area (FA-
173) in the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent
RP-184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3 RP-184-4Mean AFDM Organic Matter (mg/ft3)0
5
10
15
20
25
30
40
50
60
70
Spring
Summer
Fall
FPOM
Trib Mouth Main ChannelSide Channel
2014 Drift OM
Main Channel
Above Trib
RP- 173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4 Hess RP-173-4 PonarMean AFDM Organic Matter (g/m2)0
10
20
30
40
50
60
Spring
Summer
Fall
FPOM
Trib Mouth Side SloughMain Channel Side Channel Side Slough
2013 Benthic OM
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95-percent confidence intervals.
Figure 5.6-5. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2013
during three sampling events for sites within the Stephan Lake Complex Focus Area (FA-184) in the Middle
River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “P” indicates plankton tow samples were taken, and no organic matter was collected.
Figure 5.6-6. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2014
during three sampling events for sites within the Stephan Lake Complex Focus Area (FA-184) in the Middle
River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals. “P” indicates plankton tow samples were taken, and no organic matter was collected.
RP-173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4Mean AFDM Organic Matter (mg/ft3)0
5
10
15
20
25
40
Spring
Summer
Fall
FPOM
Trib Mouth Side SloughMain Channel Side Channel
P PPP
2013 Drift OM
RP-173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4 RP-173-5Mean AFDM Organic Matter (mg/ft3)0
1
2
3
4
5
6
7
8
9
Spring
Summer
Fall
FPOM
Trib Mouth Side SloughMain Channel Side Channel
P PPP
2014 Drift OM
Upland Slough
P
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Figure 5.6-7. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab samples
collected in 2013 during three sampling events for sites within the Indian River Focus Area (FA-141) in the
Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals.
Figure 5.6-8. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2013
during three sampling events for sites within the Indian River Focus Area (FA-141) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. “P” indicates plankton tow samples were taken, and no organic matter was collected. “N/A”
indicates that no samples were collected.
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 Hess RP-141-4 PonarMean AFDM Organic Matter (g/m2)0
25
50
75
100
125150
200
250
300
Spring
Summer
Fall
FPOM
Trib Mouth Main Channel Upland SloughSide Channel Upland Slough
2013 Benthic OM
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 RP-141-5Mean AFDM Organic Matter (mg/ft3)0
2
4
6
8
10
12
Spring
Summer
Fall
FPOM
Trib Mouth Main Channel Upland SloughSide Channel Main Channel
Above Trib
P P PP N/AN/A
2013 Drift OM
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Figure 5.6-9. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2014
during three sampling events for sites within the Indian River Focus Area (FA-141) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. “P” indicates plankton tow samples were taken, and no organic matter was collected.
Figure 5.6-10. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab samples
collected in 2013 during three sampling events for sites within the Whiskers Slough Focus Area (FA-104) in
the Middle River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals.
RP-141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4 RP-141-5Mean AFDM Organic Matter (mg/ft3)0
5
10
15
20
2540
50
Spring
Summer
Fall
FPOM
Trib Mouth Main Channel Upland SloughSide Channel Main Channel
Above Trib
P P PP
2014 Drift OM
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 Hess RP-104-2 Ponar RP-104-3 RP-104-4 Ponar RP-104-5Mean AFDM Organic Matter (g/m2)0
25
50
75
100
125
300
400
500
600
Spring
Summer
Fall
FPOM
Trib Mouth Side Slough Main Channel Upland Slough Side ChannelSide Slough
2013 Benthic OM
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Figure 5.6-11. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2013
during three sampling events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. “P” indicates plankton tow samples were taken, and no organic matter was collected.
Figure 5.6-12. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2014
during three sampling events for sites within the Whiskers Slough Focus Area (FA-104) in the Middle River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. “P” indicates plankton tow samples were taken, and no organic matter was collected.
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5Mean AFDM Organic Matter (mg/ft3)0
5
10
15
20
25
Spring
Summer
Fall
FPOM
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
P PP PP P
2013 Drift OM
RP-104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5Mean AFDM Organic Matter (mg/ft3)0
2
4
6
8
10
Spring
Summer
Fall
FPOM
Trib Mouth Side Slough Main Channel Upland Slough Side Channel
P PP PP
2014 Drift OM
P
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Figure 5.6-13. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab samples
collected in 2013 during three sampling events for sites within the Montana Creek Study Area (RP-81) in the
Lower River Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals.
Figure 5.6-14. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2013
during three sampling events for sites within the Montana Creek Study Area (RP-81) in the Lower River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. “P” indicates plankton tow samples were taken, and no organic matter was collected. “N/A”
indicates that no samples were collected.
Trib Mouth Main ChannelUpland Slough Side Channel
RP-81 (Montana Creek)
Station / Site
RP-81-1 Ponar RP-81-2 RP-81-3 RP-81-4Mean AFDM Organic Matter (g/m2)0
20
40
60
80
100
200
300
Spring
Summer
Fall
FPOM
2013 Benthic OM
RP- 81 (Montana Creek)
Station / Site
RP-81-1 RP-81-2 RP-81-3 RP-81-4 RP-81-5Mean AFDM Organic Matter (mg/ft3)0
2
4
6
8
10
12
14
16
18
Spring
Summer
Fall
FPOM
Trib Mouth Main ChannelUpland Slough Side Channel Side Channel
Above Trib Mouth
N/APP
2013 Drift OM
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Figure 5.6-15. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2013
during three sampling events for sites within the Montana Creek Study Area (RP-81) in the Lower River
Segment of the Susitna River for the River Productivity Study. Error bars represent 95-percent confidence
intervals. “P” indicates plankton tow samples were taken, and no organic matter was collected.
Figure 5.6-16. Mean benthic organic matter estimates (g/m2) from Hess and petite Ponar grab samples
collected in 2013 during three sampling events for sites within the Talkeetna River Study Area (RP-TKA) in
the for the River Productivity Study. Error bars represent 95-percent confidence intervals.
RP- 81 (Montana Creek)
Station / Site
RP-81-1 RP-81-2 RP-81-3 RP-81-4 RP-81-5Mean AFDM Organic Matter (mg/ft3)0
1
2
3
4
5
6
7
Spring
Summer
Fall
FPOM
Trib Mouth Main ChannelUpland Slough Side Channel Side Channel
Above Trib Mouth
PP
2014 Drift OM
P
RP-TKA (Talkeetna River)
Station / Site
RP-TKA-1 RP-TKA-2 Ponar RP-TKA-3Mean AFDM Organic Matter (g/m2)0
20
40
60
80
100
200
300
400
500
Spring
Summer
Fall
FPOM
Side SloughSide Channel Upland Slough
2013 Benthic OM
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Figure 5.6-17. Drift (seston) organic matter estimates (mg/ft3) from drift samples (n=2) collected in 2013
during three sampling events for sites within the Talkeetna River Study Area (RP-TKA) for the River
Productivity Study. Error bars represent 95-percent confidence intervals. “P” indicates plankton tow
samples were taken, and no organic matter was collected.
Figure 5.8-1. Mean density estimates (n=5) from Hess samples collected in July 2014 for sites in nine
tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals.
RP-TKA (Talkeetna River)
Station / Site
RP-TKA-1 RP-TKA-2 RP-TKA-3Mean AFDM Organic Matter (mg/ft3)0
2
4
6
8
10
Spring
Summer
Fall
FPOM
Side SloughSide Channel Upland Slough
P PP
2013 Drift OM
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean Density (Individuals/m2)0
10000
20000
30000
40000
50000
60000
150000
200000
250000
300000
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Figure 5.8-2. Mean and total taxa richness estimates (n=5) from Hess samples collected in July 2014 for sites
in nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 5.8-3. Mean and total EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates (n=5)
from Hess samples collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and
Upper River segments of the Susitna River for the River Productivity Study. Error bars represent 95-percent
confidence intervals.
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean Number of Taxa Collected0
10
20
30
40
50
60
70
Mean Taxa
Total Taxa
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean Number of EPT Taxa Collected0
2
4
6
8
10
12
14
16
18
20
Mean EPT
Total EPT
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Figure 5.8-4. Mean percent relative abundances of major taxonomic groups from Hess samples (n=5)
collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River
segments of the Susitna River for the River Productivity Study.
Figure 5.8-5. Mean percent relative abundances of functional feeding groups from Hess samples (n=5)
collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River
segments of the Susitna River for the River Productivity Study.
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTPercent Relative Abundance (%)0
20
40
60
80
100
Ephemeroptera Plecoptera Trichoptera Coleoptera
Chironomids Other Diptera Non-insects
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTPercent Relative Abundance (%)0
20
40
60
80
100
Gatherers Filterers Scrapers Shredders
Predators Parasites Other FFGs
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Figure 5.8-6. Mean benthic organic matter estimates (g/m2) from Hess samples (n=5) collected in July 2014
for sites in nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 5.8-7. Mean chlorophyll-a (mg/m2) from composite algae samples (n=5) collected in July 2014 for sites
in nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals.
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean AFDM Organic Matter (g/m2)0
10
20
30
40
50
60
70
CPOM
FPOM
Benthic OM
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean Chlorophyll-a (mg/m2)0
5
10
15
20
25
Spring
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Figure 5.8-8. Mean ash free dry mass (AFDM, g/m2) from composite algae samples (n=5) collected in July
2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 5.8-9. Mean drift density estimates from drift net samples (n=2) collected in July 2014 for sites in nine
tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna River for the River
Productivity Study. Error bars represent 95-percent confidence intervals.
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean Ash Free Dry Mass (g/m2)0
2
4
6
8
10
12
30
40
50
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean Drift Density (Individuals/ft3)0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
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Figure 5.8-10. Mean and total drift taxa richness estimates from drift net samples (n=2) collected in July
2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River segments of the Susitna
River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 5.8-11. Mean and total drift EPT (Ephemeroptera, Plecoptera, Trichoptera) taxa richness estimates
from drift samples (n=2) collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle
and Upper River segments of the Susitna River for the River Productivity Study. Error bars represent 95-
percent confidence intervals.
1 Density (sq m)
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean Number of Taxa Collected0
10
20
30
40
50
60
70
Mean Drift Taxa
Total Drift Taxa
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean Number of EPT Taxa Collected0
2
4
6
8
10
12
14
16
Mean Drift EPT
Total Drift EPT
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Figure 5.8-12. Mean percent relative abundances of major taxonomic groups from drift net samples (n=2)
collected in July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River
segments of the Susitna River for the River Productivity Study.
Figure 5.8-13. Mean drift (seston) organic matter estimates (g/m2) from drift net samples (n=2) collected in
July 2014 for sites in nine tributaries above Devils Canyon in the Middle and Upper River segments of the
Susitna River for the River Productivity Study. Error bars represent 95-percent confidence intervals.
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTPercent Relative Abundance (%)0
20
40
60
80
100
Ephemeroptera Plecoptera Trichoptera Chironomids
Other Diptera Terrestrial Insects Non-insects Zooplankton
Tributaries Above Devils Canyon
Station / Site
DEV FOG DED WAT KOS JAY OSH TYO BUTMean AFDM Organic Matter (mg/ft3)0.0
0.5
1.0
1.5
2.0
2.5
CPOM
FPOM
Drift OM
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Figure 5.8-14. Mean density estimates (n=5) from petite Ponar samples collected in July 2014 for sites within
three lakes in the Upper River Segment of the Susitna River for the River Productivity Study. Error bars
represent 95-percent confidence intervals.
Figure 5.8-15. Mean and total taxa richness estimates (n=5) from petite Ponar samples collected in July 2014
for sites within three lakes in the Upper River Segment of the Susitna River for the River Productivity Study.
Error bars represent 95-percent confidence intervals.
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Mean Density (Individuals/m2)0
2000
4000
6000
8000
10000
Lake Tyone Lake Susitna Lake Louise
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Mean Number of Taxa Collected0
4
8
12
16
20
24
28
32
Mean Taxa
Total Taxa
Lake Tyone Lake Susitna Lake Louise
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Figure 5.8-15. Mean and total chironomid (midge) taxa richness estimates (n=5) from petite Ponar samples
collected in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 5.8-16. Mean percent relative abundances of major taxonomic groups from petite Ponar samples
collected in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study.
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Mean Number of Chironomid Taxa Collected0
2
4
6
8
10
12
14
16
18
Mean Taxa
Total Taxa
0
Lake Tyone Lake Susitna Lake Louise
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Percent Relative Abundance (%)0
20
40
60
80
100
Ephemeroptera Plecoptera Trichoptera Coleoptera
Chironomids Other Diptera Non-insects
Lake Tyone Lake Susitna Lake Louise
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Figure 5.8-17. Mean percent relative abundances of functional feeding groups from petite Ponar samples
collected in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study.
Figure 5.8-18. Mean benthic organic matter estimates (g/m2) from petite Ponar samples collected in July
2014 for sites within three lakes in the Upper River Segment of the Susitna River for the River Productivity
Study. Error bars represent 95-percent confidence intervals.
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Percent Relative Abundance (%)0
20
40
60
80
100
Gatherers Filterers Scrapers Shredders
Predators Parasites Other FFGs
Lake Tyone Lake Susitna Lake Louise
Upper Susitna Basin Lakes
Lake / SiteMean AFDM Organic Matter (g/m2)0
100
200
300
400
CPOM
FPOM
Benthic OM
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3
Lake Tyone Lake Susitna Lake Louise
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Figure 5.8-18. Taxa richness, chironomid taxa richness, and EPT taxa richness estimates from qualitative
shoreline D-net sweep samples collected in July 2014 for sites within three lakes in the Upper River Segment
of the Susitna River for the River Productivity Study.
Figure 5.8-19. Mean percent relative abundances of major taxonomic groups from qualitative shoreline D-
net sweep samples collected in July 2014 for sites within three lakes in the Upper River Segment of the
Susitna River for the River Productivity Study.
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Number of Taxa Collected in D-net Sweeps0
10
20
30
40
50
Total Taxa
Chironomid Taxa
EPT Taxa
Lake Tyone Lake Susitna Lake Louise
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Percent Relative Abundance (%)0
20
40
60
80
100
Lake Tyone Lake Susitna Lake Louise
Ephemeroptera Plecoptera Trichoptera Coleoptera
Chironomidae Other Diptera Other Insects Non-insects
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Figure 5.8-20. Mean percent relative abundances of functional feeding groups from qualitative shoreline D-
net sweep samples collected in July 2014 for sites within three lakes in the Upper River Segment of the
Susitna River for the River Productivity Study.
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Percent Relative Abundance (%)0
20
40
60
80
100
Gatherers Filterers Scrapers Shredders
Predators Parasites Other FFGs
Lake Tyone Lake Susitna Lake Louise
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Figure 5.8-21. Mean plankton tow density estimates (individuals/m2) from vertical tow net samples (n=5)
collected in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals.
Figure 5.8-22. Mean plankton tow dry weight biomass estimates (mg/m2) from vertical tow net samples (n=5)
collected in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study. Error bars represent 95-percent confidence intervals.
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Mean Estimated Density (Individuals/m2)0
50000
100000
150000
200000
250000
300000
350000
Plankton Density
Lake Tyone Lake Susitna Lake Louise
Upper Susitna Basin Lakes
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Mean Estimated Biomass (mg/m2)0
100
200
300
400
500
600
700
Plankton Biomass
Lake Tyone Lake Susitna Lake Louise
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 227 October 2015
Figure 5.8-23. Mean percent relative abundances of zooplankton taxa density and biomass from vertical tow
net samples (n=5) collected in July 2014 for sites within three lakes in the Upper River Segment of the Susitna
River for the River Productivity Study.
Upper Susitna Basin Lakes
Density
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Percent Relative Abundance Density (%)0
20
40
60
80
100
Biomass
Lake / Site
LTY-1 LTY-2 LTY-3 LSU-1 LSU-2 LSU-3 LLO-1 LLO-2 LLO-3Percent Relative Abundance Biomass (%)0
20
40
60
80
100
Lake Tyone Lake Susitna Lake Louise
Lake Tyone Lake Susitna Lake Louise
Eubosmina longispina Daphnia longiremis D. ambigua Other Cladocera
Copepoda - nauplii Copepoda - Calanoida Copepoda - Cyclopoida
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 228 October 2015
Figure 5.8-24. Depth profiles for temperature and photosynthetically active radiation (PAR) light levels
recorded in July 2014 for sites within three lakes in the Upper River Segment of the Susitna River for the
River Productivity Study. “*” indicates measurements were limited by probe cable length (approx. 96 ft),
and did not reach the lake bottom.
0
4
8
12
16
20
24
4 6 8 10 12 14 16 18
Depth (ft)Temperature (°C)
RP-LTY
RP-LTY-1
RP-LTY-2
RP-LTY-3
0
10
20
30
40
50
60
70
80
90
100
4 6 8 10 12 14 16 18
Depth (ft)Temperature (°C)
RP-LSU
RP-LSU-1
RP-LSU-2
RP-LSU-3
0
10
20
30
40
50
60
70
80
90
100
4 6 8 10 12 14 16 18
Depth (ft)Temp erature (°C)
RP-LLO
RP-LLO-1
RP-LLO-2
RP-LLO-3
0
4
8
12
16
20
24
0 500 1000 1500 2000
Depth (ft)PAR (μmol)
RP-LTY
RP-LTY-1
RP-LTY-2
RP-LTY-3
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500
Depth (ft)PAR (μmol)
RP-LSU
RP-LSU-1
RP-LSU-2
RP-LSU-3
0
10
20
30
40
50
60
70
80
90
100
0 200 400 600 800 1000 1200 1400
Depth (ft)PAR (μmol)
RP-LLO
RP-LLO-1
RP-LLO-2
RP-LLO-3
****
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 229 October 2015
Figure 5.8-25. Depth profiles for dissolved oxygen (DO) and percent dissolved oxygen recorded in July 2014
for sites within three lakes in the Upper River Segment of the Susitna River for the River Productivity Study.
“*” indicates measurements were limited by probe cable length (approx. 96 ft), and did not reach the lake
bottom.
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12
Depth (ft)DO (mg/L)
RP-LSU
RP-LSU-1
RP-LSU-2
RP-LSU-3
0
4
8
12
16
20
24
0 2 4 6 8 10 12
Depth (ft)DO (mg/L)
RP-LTY
RP-LTY-1
RP-LTY-2
RP-LTY-3
0
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100 120
Depth (ft)DO (%)
RP-LSU
RP-LSU-1
RP-LSU-2
RP-LSU-3
0
4
8
12
16
20
24
0 20 40 60 80 100 120
Depth (ft)DO (%)
RP-LTY
RP-LTY-1
RP-LTY-2
RP-LTY-3
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12
Depth (ft)DO (mg/L)
RP-LLO
RP-LLO-1
RP-LLO-2
RP-LLO-3
0
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100 120
Depth (ft)DO (%)
RP-LLO
RP-LLO-1
RP-LLO-2
RP-LLO-3
****
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 230 October 2015
Figure 5.8-26. Depth profiles for general and specific conductivity recorded in July 2014 for sites within three
lakes in the Upper River Segment of the Susitna River for the River Productivity Study. “*” indicates
measurements were limited by probe cable length (approx. 96 ft), and did not reach the lake bottom.
0
10
20
30
40
50
60
70
80
90
100
100 105 110 115 120 125 130 135
Depth (ft)GenCond (µS/cm)
RP-LLO
RP-LLO-1
RP-LLO-2
RP-LLO-3
0
10
20
30
40
50
60
70
80
90
100
200 250 300 350 400 450 500
Depth (ft)GenCond (µS/cm)
RP-LSU
RP-LSU-1
RP-LSU-2
RP-LSU-3
0
4
8
12
16
20
24
250 260 270 280 290 300
Depth (ft)GenCond (µS/cm)
RP-LTY
RP-LTY-1
RP-LTY-2
RP-LTY-3
0
4
8
12
16
20
24
320 330 340 350 360 370 380 390
Depth (ft)SpCond (µS/cm)
RP-LTY
RP-LTY-1
RP-LTY-2
RP-LTY-3
0
10
20
30
40
50
60
70
80
90
100
300 400 500 600 700 800
Depth (ft)SpCond (µS/cm)
RP-LSU
RP-LSU-1
RP-LSU-2
RP-LSU-3
0
10
20
30
40
50
60
70
80
90
100
154 156 158 160 162 164 166 168
Depth (ft)SpCond (µS/cm)
RP-LLO
RP-LLO-1
RP-LLO-2
RP-LLO-3
****
STUDY IMPLEMENTATION REPORT RIVER PRODUCTIVITY STUDY (STUDY 9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 231 October 2015
Figure 5.8-27. Depth profiles for pH and Oxidation Reduction Potential (ORP) recorded in July 2014 for
sites within three lakes in the Upper River Segment of the Susitna River for the River Productivity Study.
“*” indicates measurements were limited by probe cable length (approx. 96 ft), and did not reach the lake
bottom.
0
4
8
12
16
20
24
6.8 7 7.2 7.4 7.6 7.8 8 8.2 8.4 8.6
Depth (ft)pH
RP-LTY
RP-LTY-1
RP-LTY-2
RP-LTY-3
0
10
20
30
40
50
60
70
80
90
100
6.8 7 7.2 7.4 7.6 7.8 8 8.2 8.4 8.6
Depth (ft)pH
RP-LSU
RP-LSU-1
RP-LSU-2
RP-LSU-3
0
10
20
30
40
50
60
70
80
90
100
6.8 7 7.2 7.4 7.6 7.8 8 8.2 8.4 8.6
Depth (ft)pH
RP-LLO
RP-LLO-1
RP-LLO-2
RP-LLO-3
0
4
8
12
16
20
24
0 50 100 150 200 250 300 350 400
Depth (ft)ORP mV
RP-LTY
RP-LTY-1
RP-LTY-2
RP-LTY-3
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300 350 400
Depth (ft)ORP mV
RP-LSU
RP-LSU-1
RP-LSU-2
RP-LSU-3
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300 350 400
Depth (ft)ORP mV
RP-LLO
RP-LLO-1
RP-LLO-2
RP-LLO-3
***