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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
Draft technical memorandum, Selection of focus areas and study sites in
the middle Susitna River for instream flow and joint resource studies - 2013
and 2014
SuWa 27
Author(s) – Personal:
Author(s) – Corporate:
R2 Resource Consultants, Inc.
AEA-identified category, if specified:
January 31, 2013 Filing
AEA-identified series, if specified:
Series (ARLIS-assigned report number):
Susitna-Watana Hydroelectric Project document number 27
Existing numbers on document:
Published by:
[Anchorage, Alaska : Alaska Energy Authority, 2013]
Date published:
January 31, 2013
Published for:
Prepared for Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Attachment E
Final or Draft status, as indicated:
Draft
Document type:
Technical memorandum
Pagination:
vii, 43 p.
Related work(s):
Cover letter (SuWa 22), Attachments A-D (SuWa 23-26)
Pages added/changed by ARLIS:
Added cover letter
Notes:
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/
1
January 31,2013
Ms. Kimberly Bose
Secretary
Federal Energy Regulatory Commission
888 First Street, NE
Washington, DC 20426
Re: Susitna-Watana Hydroelectric Project, FERC Project No. 14241-000
Dear Secretary Bose:
By letter dated January 17, 2013, Staff of the Federal Energy Regulatory
Commission (Commission) issued a modified schedule for its April 1, 2013 study plan
determination (SPD)for 13 of the individual studies contained in the Alaska Energy
Authority’s (AEA) Revised Study Plan (RSP) for the Susitna-Watana Hydroelectric
Project, FERC Project No. 14241.1 Among other milestones, Staff’s modified schedule
required AEA to file specified information related to these 13 individual studies by
January 31, 2013, and to convene public meetings on February 14-15, 2013, to discuss
these materials with federal and state resource agencies and other licensing participants.
In accordance with Staff’s modified schedule, the purposes of this filing are to: (1)
submit all information specified by Staff for filing by January 31; and (2) provide details
of the public meetings to be held in Anchorage, Alaska, on February 14-15, 2013.
Description of Attached Information
Commission Staff’s January 17 modified schedule required AEA to file the
following information by January 31, 2013:
results of 2012 open-water flow routing model and habitat mapping; draft
implementation plans for the Fish Distribution and Abundance in the
Upper Susitna River (study 9.5), the Fish Distribution and Abundance in
the Lower and Middle Susitna River (study 9.6), and River Productivity
1 See Letter from Jeff C. Wright, Federal Energy Regulatory Commission, to Wayne Dyok, Alaska
Energy Authority, Attachment A, Project No. 14241-000 (issued Jan. 17, 2013)[hereinafter, Schedule
Modification Letter]. The 13 individual studies scheduled for Staff’s April 1 SPD consist of the following:
(1) Baseline Water Quality (RSP 5.5); (2) Water Quality Modeling Study (RSP 5.6); (3) Mercury
Assessment and Potential for Bioaccumulation Study (RSP 5.7); (4) Geomorphology Study (RSP 6.5); (5)
Fluvial Geomorphology Modeling Below Watana Dam Study (RSP 6.6); (6) Groundwater Study (RSP 7.5);
(7) Ice Processes in the Susitna River Study (RSP 7.6); (8) Fish and Aquatics Instream Flow Study (RSP
8.5); (9) Riparian Instream Flow Study (RSP 8.6); (10) Study of Fish Distribution and Abundance in the
Upper Susitna River (RSP 9.5); (11) Study of Fish Distribution and Abundance in the Middle and Lower
Susitna River (RSP 9.6); (12) River Productivity Study (RSP 9.8); and (13) Characterization and Mapping
of Aquatic Habitats (RSP 9.9).
2
(study 9.8) studies; all proposed focus areas; and a description of habitat
units within the focus areas for all aquatic studies to be implemented in the
middle Susitna River.2
In response to Staff’s request, and in furtherance of its efforts to finalize study reports
associated with its 2012 early licensing studies, AEA has prepared several study reports
and technical memoranda containing all the requested information. The information
requested by Commission Staff appears in the attachments as follows:
Requested Information Attachment
Results of 2012 Open-Water Flow Routing Attachment A, Open Water HEC-RAS
Flow Routing Model (January 2013)
Results of 2012 Habitat Mapping Attachment B, Middle Susitna River
Segment Remote Line Habitat Mapping
Technical Memo (January 2013)
Draft Implementation Plan for Study of
Fish Distribution and Abundance in the
Upper Susitna River (RSP 9.5)
Attachment C, Draft Susitna River Fish
Distribution and Abundance
Implementation Plan (January 2013)
Draft Implementation Plan for Study of
Fish Distribution and Abundance in the
Middle and Lower Susitna River (RSP 9.6)
Attachment C, Draft Susitna River Fish
Distribution and Abundance
Implementation Plan (January 2013)
Draft Implementation Plan for River
Productivity Study (RSP 9.8)
Attachment D, Draft Susitna River
Productivity Study Implementation Plan
(January 2013)
Proposed Focus Areas Attachment E, Selection of Focus Areas
and Study Sites in the Middle and Lower
Susitna River for Instream Flow and Joint
Resource Studies –2013 and 2014
(January 2013)
Description of Habitat Units within Focus
Areas for All Aquatic Studies to Be
Implemented in the Middle Susitna River
Attachment E, Selection of Focus Areas
and Study Sites in the Middle and Lower
Susitna River for Instream Flow and Joint
Resource Studies –2013 and 2014
(January 2013)
Details of Public Meetings
Commission Staff’s modified schedule directed AEA to hold meetings on
February 14-15, 2013, “to discuss the study results, proposed implementation plans, and
selected focus areas in the middle and lower Susitna River.”3 These Technical
Workgroup (TWG) meetings, which are open to federal and state resource agencies, other
licensing participants, and interested members of the public, will begin each day at 8:30
a.m. (Alaska Standard Time), and will be held in the Public Conference Room of the Z.J.
2 Schedule Modification Letter, Attachment A.
3 Id.
3
Loussac Public Library, located at 3600 Denali Street, Anchorage, Alaska. Additional
information regarding these TWG meetings—including instructions for participating
online and via teleconference for those unable to attend in person—appear at AEA’s
licensing website, http://www.susitna-watanahydro.org/meetings/. More detailed
information regarding these TWG meetings, including a draft agenda, will be posted to
the website in the coming days.
AEA looks forward to discussing these materials in the upcoming TWG meetings.
These discussions will inform and assist AEA in its development of the final
implementation plans for the Study of Fish Distribution and Abundance in the Upper
Susitna River (RSP 9.5), Study of Fish Distribution and Abundance in the Middle and
Lower Susitna River (RSP 9.6), and River Productivity Study (RSP 9.8). As provided in
Commission Staff’s modified schedule, AEA will file these final implementation plans
with the Commission by March 1, 2013.
AEA acknowledges and greatly appreciates the participation and commitment to
this licensing process of Commission Staff, federal and state resource agencies, and other
licensing participants. AEA is particularly appreciative of all participants’ efforts to date
to work efficiently and collaboratively in developing a robust study plan that can be
approved by Commission Staff in accordance with the modified schedule and
implemented beginning with the 2013 field season.
If you have questions concerning this submission please contact me at
wdyok@aidea.org or (907) 771-3955.
Sincerely,
Wayne Dyok
Project Manager
Alaska Energy Authority
Attachments
cc: Distribution List (w/o Attachments)
Attachment E
Selection of Focus Areas and Study Sites in the Middle and Lower Susitna River
for Instream Flow and Joint Resource Studies – 2013 and 2014 (January 2013)
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Draft 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
Prepared by
R2 Resource Consultants, Inc.
January 31, 2013
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i Draft - January 31, 2013
TABLE OF CONTENTS
1. Introduction ................................................................................................................... 1
2. Objectives ....................................................................................................................... 1
3. Review of River Stratification and Study Area Selection Process ............................... 2
3.1. River Stratification ......................................................................................... 2
3.2. Selection of Study Areas/Study Sites .............................................................. 4
3.2.1. Representative Sites ......................................................................4
3.2.2. Critical Sites .................................................................................5
3.2.3. Randomly Located Sites ...............................................................5
3.2.4. Focus Areas ..................................................................................5
4. Focus Areas and Study Sites Identified in the IFS RSP ............................................... 7
4.1. Focus Areas ................................................................................................... 7
4.2. Sites Outside of the Focus Areas .................................................................... 8
5. Habitat Mapping Analysis............................................................................................. 9
5.1. Methods ....................................................................................................... 10
5.1.1. Habitat Data Compilation and Review ........................................ 10
5.1.2. Evaluation of Representativeness – Representation and
Proportionality ............................................................................ 10
5.1.3. Evaluation of Representativeness – Bias ..................................... 11
5.2. Results ......................................................................................................... 11
5.2.1. Habitat Data Compilation and Review ........................................ 11
5.2.2. Evaluation of Representativeness ................................................ 12
6. Implications of Habitat Mapping Results and Study Area Refinements................... 13
7. Final Listing of Focus Areas and Study Sites ............................................................. 14
8. References .................................................................................................................... 15
9. Tables ........................................................................................................................... 16
10. Figures.......................................................................................................................... 27
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii Draft - January 31, 2013
LIST OF TABLES
Table 1. Locations, descriptions and selection rationale of proposed Focus Areas for detailed
study in the Middle River Segment of the Susitna River. Focus Area identification numbers
(e.g., Focus Area 184) represent the truncated Project River Mile (PRM) at the downstream
end of each Focus Area. ..................................................................................................... 17
Table 2. Partial list of river cross-sections, and flow and water surface elevations measured in
2012 on the Susitna River between River Miles 75 and 184. The list does not include
additional measurements in late September/October. Those measurements had not been
processed at the time this study plan was prepared. ............................................................ 18
Table 3. Metrics used to compare the representation and proportionality of habitat types between
focus areas and non-focus areas within each geomorphic reach.......................................... 21
Table 4. Main channel habitat classifications by geomorphic reach in the Middle Susitna River
.......................................................................................................................................... 22
Table 5. Main Channel mesohabitat classifications in the Middle Susitna River. ...................... 23
Table 6. Off channel habitats classified in the Middle Susitna River. ........................................ 24
Table 7. Counts of tributaries with potential fish habitat in the Middle River. ........................... 25
Table 8. Estimated bias for each proportionality metric (total for reach – focus area) where
estimates could be made. Statistical comparison was made using a t-test or nonparametric
alternative when the sample size (number of geomorphic reaches with bias estimate) was
greater than three. .............................................................................................................. 25
Table 9. Habitat types by geomorphic reach and how representativeness will be achieved.
(FA=Focus Area; CS=Cross-section). ................................................................................ 26
LIST OF FIGURES
Figure 1. Map of the Middle Segment of the Susitna River depicting the eight Geomorphic
Reaches and locations of proposed Focus Areas. No Focus Areas are proposed for in MR-3
and MR-4 due to safety issues related to sampling within or proximal to Devils Canyon. .. 28
Figure 2. Map of the Lower Segment of the Susitna River depicting the six Geomorphic
Reaches. Focus Areas have not been identified in this segment but will be considered
pending results of open-water flow routing modeling......................................................... 29
Figure 3. Map showing Focus Area 184 that begins at Project River Mile 184.7 and extends
upstream to PRM 185.7. The Focus Area is located about 1.4 miles downstream of the
proposed Watana Dam site near Tsusena Creek. ................................................................ 30
Figure 4. Map showing Focus Area 173 beginning at Project River Mile 173.6 and extends
upstream to PRM 175.4. This Focus Area is near Stephan Lake and consists of main
channel and a side channel complex. ................................................................................. 31
Figure 5. Map showing Focus Area 171 beginning at Project River Mile 171.6 and extends
upstream to PRM 173. This Focus Area is near Stephan Lake and consists of main channel
and a single side channel with vegetated island. ................................................................. 32
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii Draft - January 31, 2013
Figure 6. Map showing Focus Area 151 beginning at Project River Mile 151.8 and extends
upstream to PRM 152.3. This single main channel Focus Area is at the Portage Creek
confluence. ........................................................................................................................ 33
Figure 7. Map showing Focus Area 144 beginning at Project River Mile 144.4 and extends
upstream to PRM 145.7. This Focus Area is located about 2.3 miles upstream of Indian
River and includes Side Channel 21 and Slough 21............................................................ 34
Figure 8. Map showing Focus Area 141 beginning at Project River Mile 141.8 and extends
upstream to PRM 143.4. This Focus Area includes the Indian River confluence and a range
of main channel and off-channel habitats. .......................................................................... 35
Figure 9. Map showing Focus Area 138 beginning at Project River Mile 138.7 and extends
upstream to PRM 140. This Focus Area is near Gold Creek and consists of a complex of
side channel, side slough and upland slough habitats including Upper Side Channel 11 and
Slough 11. ......................................................................................................................... 36
Figure 10. Map showing Focus Area 128 beginning at Project River Mile 128.1 and extends
upstream to PRM 129.7. This Focus Area consists of side channel, side slough and
tributary confluence habitat features including Skull Creek................................................ 37
Figure 11. Map showing Focus Area 115 beginning at Project River Mile 115.3 and extends
upstream to PRM 116.5. This Focus Area is located about 0.6 miles downstream of Lane
Creek and consists of side channel and upland slough habitats including Slough 6A. ......... 38
Figure 12. Map showing Focus Area 104 beginning at Project River Mile 104.8 and extends
upstream to PRM 106. This Focus Area covers the diverse range of habitats in the
Whiskers Slough complex. ................................................................................................ 39
Figure 13. Percent of main channel in single main, split main, and braided main channel habitat
by geomorphic reach and focus area (F), non-focus area (NF), and total (T). ..................... 40
Figure 14. Side channel, side slough, and upland slough lengths per mile of main channel by
geomorphic reach and focus area (F), non-focus area (NF), and total (T). .......................... 41
Figure 15. Percent of slough habitat that is in beaver complex by geomorphic reach and focus
area (F), non-focus area (NF), and total (T). ....................................................................... 41
Figure 16. Backwaters, tributaries, tributary mouths, and plumes by geomorphic reach and focus
area (F), non-focus area (NF), and total (T). Top graph is counts. Bottom graph is density
(#/mile). ............................................................................................................................ 42
Figure 17. Percent of main and side channel habitat that is in riffle vs. glide/run habitat by
geomorphic reach and focus area (F), non-focus area (NF), and total (T). .......................... 43
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv Draft - January 31, 2013
LIST OF ACRONYMS AND SCIENTIFIC LABELS
Abbreviation Definition
AEA Alaska Energy Authority
Backwater
Off-channel habitat characterization feature found along channel margins and
generally within the influence of the active main channel with no independent
source of inflow. Water is not clear.
Baseline
Baseline (or Environmental Baseline): the environmental conditions that are the
starting point for analyzing the impacts of a proposed licensing action (such as
approval of a license application) and any alternative.
Beaver complex Off-channel habitat characterization feature consisting of a ponded water body
created by beaver dams.
Braided streams
Stream consisting of multiple small, shallow channels that divide and recombine
numerous times. Associated with glaciers, the braiding is caused by excess
sediment load.
Cascade
The steepest of riffle habitats. Unlike rapids, which have an even gradient,
cascades consist of a series of small steps of alternating small waterfalls and
shallow pools.
Cfs cubic feet per second
Channel A natural or artificial watercourse that continuously or intermittently contains water,
with definite bed and banks that confine all but overbank stream flows.
Conductivity In terms of water conductivity, the ability of water to conduct electricity, normally
through the presence of dissolved solids that carry electrical charges.
Confluence The junction of two or more rivers or streams.
Cross-section A plane across a river or stream channel perpendicular to the direction of water
flow.
Devils Canyon
Located at approximately Susitna River Mile (RM) 150-161, Devils Canyon contains
four sets of turbulent rapids rated collectively as Class VI. This feature is a partial
fish barrier because of high water velocity.
Distribution (species) The manner in which a biological taxon is spatially arranged.
Edge habitat The boundary between natural habitats, in this case between land and a stream.
Level five tier of the habitat classification system.
Escapement (spawning) The number or proportion of fish surviving (escaping from) a given fishery at the
end of the fishing season and reaching the spawning grounds.
et al. “et alia”; and the rest
FA Focus Area
FERC Federal Energy Regulatory Commission
Floodplain
1. The area along waterways that is subject to periodic inundation by out-of-bank
flows. 2. The area adjoining a water body that becomes inundated during periods of
over-bank flooding and that is given rigorous legal definition in regulatory programs.
3. Land beyond a stream channel that forms the perimeter for the maximum
probability flood. 4. A relatively flat strip of land bordering a stream that is formed by
sediment deposition. 5. A deposit of alluvium that covers a valley flat from lateral
erosion of meandering streams and rivers.
Floodplain vegetation − groundwater /
surface water regime functional groups
Assemblages of plants that have established and developed under similar
groundwater and surface water hydrologic regimes.
Fluvial Of or pertaining to the processes associated with rivers and streams and the
deposits and landforms created by them.
Focus Area Areas selected for intensive investigation by multiple disciplines as part of the AEA
study program.
Geomorphic reach Level two tier of the habitat classification system. Separates major hydraulic
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v Draft - January 31, 2013
Abbreviation Definition
segments into unique reaches based on the channel’s geomorphic characteristic.
GIS
Geographic Information System. An integrated collection of computer software and
data used to view and manage information about geographic places, analyze
spatial relationships, and model spatial processes.
Glide An area with generally uniform depth and flow with no surface turbulence. Low
gradient; 0-1 % slope.
Gradient The rate of change of any characteristic, expressed per unit of length (see Slope).
May also apply to longitudinal succession of biological communities.
Groundwater (GW) In the broadest sense, all subsurface water; more commonly that part of the
subsurface water in the saturated zone.
Habitat
The environment in which the fish live, including everything that surrounds and
affects its life, e.g. water quality, bottom, vegetation, associated species (including
food supplies). The locality, site and particular type of local environment occupied
by an organism.
Instream flow The rate of flow in a river or stream channel at any time of year.
Juvenile A young fish or animal that has not reached sexual maturity.
licensing participants; Participants Agencies, ANSCA corporations, Alaska Native entities and other licensing
participants
Life stage
An arbitrary age classification of an organism into categories relate to body
morphology and reproductive potential, such as spawning, egg incubation, larva or
fry, juvenile, and adult.
Lower segment Susitna The Susitna River from Cook Inlet (RM 0) to the confluence of the Chulitna River at
RM 98.
LR Lower River Reach
Main channel For habitat classification system: a single dominant main channel. Also, the primary
downstream segment of a river, as contrasted to its tributaries.
Main channel habitat
Level four tier of the habitat classification system. Separates main channel habitat
types including: tributary mouth, main channel, split main channel, multiple split
main channel and side channel into mesohabitat types. Mesohabitat tyes include
pool, glide, run, riffle, and rapid.
Mainstem
Mainstem refers to the primary river corridor, as contrasted to its tributaries.
Mainstem habitats include the main channel, split main channels, side channels,
tributary mouths, and off-channel habitats.
Mainstem habitat
Level three tier of the habitat classification systems. Separates mainstem habitat
into main channel, off-channel, and tributary habitat types. Main channel habitat
types include: tributary mouth, main channel, split main channel, multiple split main
channel and side channel. Off-channel habitat types include: side slough, upland
slough, backwater, and beaver complex. Tributary habitat is not further categorized.
Mesohabitat
A discrete area of stream exhibiting relatively similar characteristics of depth,
velocity, slope, substrate, and cover, and variances thereof (e.g., pools with
maximum depth <5 ft, high gradient rimes, side channel backwaters).
Mi mile(s)
Middle segment Susitna The Susitna River from the confluence of the Chulitna River at RM 98 to the
proposed Watana Dam Site at RM 184.
Migrant (life history type) Some species exhibit a migratory life history type and undergo a migration to from
rivers/lakes/ocean.
Migration Systematic (as opposed to random) movement of individuals of a stock from one
place to another, often related to season.
MR Middle River Reach
Multiple split main channel Main channel habitat characterization feature where more than three distributed
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vi Draft - January 31, 2013
Abbreviation Definition
dominant channels are present.
N/A not applicable or not available
Off-channel Those bodies of water adjacent to the main channel that have surface water
connections to the main river at some discharge levels.
Off-channel habitat Habitat within those bodies of water adjacent to the main channel that have surface
water connections to the main river at some discharge levels.
PHABSIM
Physical Habitat Simulation, aspecific model designed to calculate an index to the
amount of microhabitat available for different life stages at different flow levels.
PHABSIM has two major analytical components: stream hydraulics and life stage-
specific habitat requirements.
Pool Slow water habitat with minimal turbulence and deeper due to a strong hydraulic
control.
PRM
Project River Mile(s) based on the digitized wetted width centerline of the main
channel from 2012 Matanuska-Susitna Borough digital orthophotos. PRM 0.0 is
established as mean lower low water of the Susitna River confluence at Cook Inlet.
Project Susitna-Watana Hydroelectric Project
PSP Proposed Study Plan
Radiotelemetry Involves the capture and placement of radio-tags in adult fish that allow for the
remote tracking of movements of individual fish.
Rapid
Swift, turbulent flow including small chutes and some hydraulic jumps swirling
around boulders. Exposed substrate composed of individual boulders, boulder
clusters, and partial bars. Lower gradient and less dense concentration of boulders
and white water than Cascade. Moderate gradient; usually 2.0-4.0% slope.
Rearing Rearing is the term used by fish biologists that considers the period of time in which
juvenile fish feed and grow.
Riffle
A fast water habitat with turbulent, shallow flow over submerged or partially
submerged gravel and cobble substrates. Generally broad, uniform cross-section.
Low gradient; usually 0.5-2.0% slope.
Riparian Pertaining to anything connected with or adjacent to the bank of a stream or other
body of water.
River A large stream that serves as the natural drainage channel for a relatively large
catchment or drainage basin.
River mile The distance of a point on a river measured in miles from the river's mouth along
the low-water channel.
RM River Mile(s) referencing those of the APA Project.
RSP Revised Study Plan
Run (habitat)
A habitat area with minimal surface turbulence over or around protruding boulders
with generally uniform depth that is generally greater than the maximum substrate
size. Velocities are on border of fast and slow water. Gradients are approximately
0.5 % to less than 2%. Generally deeper than riffles with few major flow
obstructions and low habitat complexity.
Run (migration)
Seasonal migration undertaken by fish, usually as part of their life history; for
example, spawning run of salmon, upstream migration of shad. Fishers may refer to
increased catches as a “run” of fish, a usage often independent of their migratory
behavior.
Sediment Solid material, both mineral and organic, that is in suspension in the current or
deposited on the streambed.
Sediment transport
The movement of solid particles (sediment), typically due to a combination of the
force of gravity acting on the sediment, and/or the movement of the fluid in which
the sediment is entrained.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vii Draft - January 31, 2013
Abbreviation Definition
Side channel
Lateral channel with an axis of flow roughly parallel to the mainstem, which is fed by
water from the mainstem; a braid of a river with flow appreciably lower than the
main channel. Side channel habitat may exist either in well-defined secondary
(overflow) channels, or in poorly-defined watercourses flowing through partially
submerged gravel bars and islands along the margins of the mainstem.
Side slough Off-channel habitat characterization of an Overflow channel contained in the
floodplain, but disconnected from the main channel. Has clear water,
Slough
A widely used term for wetland environment in a channel or series of shallow lakes
where water is stagnant or may flow slowly on a seasonal basis. Also known as a
stream distributary or anabranch.
Spawning The depositing and fertilizing of eggs by fish and other aquatic life.
Split main channel Main channel habitat characterization where three of fewer distributed dominant
channels.
Thalweg A continuous line that defines the deepest channel of a watercourse.
Three Rivers Confluence
The confluence of the Susitna, Chulitna, and Talkeetna rivers at Susitna River Mile
(RM) 98.5 represents the downstream end of the Middle River and the upstream
end of the Upper River.
TM Technical Memorandum
Tributary A stream feeding, joining, or flowing into a larger stream (at any point along its
course or into a lake). Synonyms: feeder stream, side stream.
Tributary mouth Main channel habitat characterization of clear water areas that exist where
tributaries flow into Susitna River main channel or side channel habitats.
TWG Technical Workgroup
U.S., US United States
Upwelling
The movement of groundwater into rivers, stream, sloughs and other surface water
features. This is also called groundwater discharge and may be associated with a
gaining reach of a river or stream.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 Draft - January 31, 2013
1. INTRODUCTION
Construction and operation of the Susitna-Watana Hydroelectric Project (Project) will affect
Susitna River flows downstream of the dam; the degree of these effects will ultimately depend
on final Project design and operating characteristics. The Project will be operated in a load-
following mode. Project operations will cause seasonal, daily, and hourly changes in Susitna
River flows compared to existing conditions. The potential alteration in flows will influence
downstream resources/processes, including fish and aquatic biota and their habitats, channel
form and function including sediment transport, water quality, groundwater/surface water
interactions, ice dynamics, and riparian and wildlife communities (AEA 2011).
The potential operational flow-induced effects of the Project will need to be evaluated as part of
the licensing process and a Revised Study Plan (RSP) has been prepared and submitted to the
Federal Energy Regulatory Commission (FERC) that describes the Susitna-Watana Instream
Flow Study (RSP Section 8.5) that will be conducted to characterize and evaluate these effects.
The plan includes a statement of objectives, a description of the technical framework that is at
the foundation of the Instream Flow Study (IFS), the general methods that will be applied, and
the study nexus to the Project.
Since submittal of the RSP, FERC issued a Revised Study Plan Determination Schedule (January
17, 2013) that specified deliverables of two IFS related analyses; 1) results of the open-water
flow routing model, and 2) identification of all proposed Focus Areas (FAs) with a description of
habitat units within the FAs for all aquatic studies to be implemented in the middle Susitna
River. This Technical Memorandum (TM) pertains to the Focus Areas; a separate TM has been
prepared that describes the open-water flow routing model results (R2 et al. 2013).
2. OBJECTIVES
Specific objectives of this TM include:
Review the general approach to stratification and the study site selection process used in
the IFS RSP (see Section 8.5.4.2);
Identify the 10 FAs that were initially described in the RSP (Section 8.5.4.2.1.2) and the
criteria that were used in their selection;
Describe and summarize the statistical analysis completed on the habitat mapping results
of the Middle River Segment with respect to the 10 FAs and their habitat units;
Describe the implications of the habitat analysis and any modifications to the study site
selection process, including refinements in FAs, and the need to identify supplemental
sites or areas;
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 Draft - January 31, 2013
List all proposed FAs and study sites outside of the FAs for all IFS related studies to be
implemented in the Middle River Segment of the Susitna River 1.
The overall objective of the TM is to describe the rationale and basis for selection of the FAs
identified in the IFS RSP and to present the results and conclusions from the habitat mapping
analysis that was completed to evaluate the representativeness of the FAs.
It is important to note that there are two lines of inquiry relative to the representativeness of the
FAs for the IFS, one for the Fish and Aquatics IFS and one for the Riparian IFS. This TM is
focused on the Fish and Aquatics IFS and is based on results of the habitat mapping analysis that
provided information concerning in-channel habitat characteristics that lend themselves to a
comparative analysis between features (habitat types) within and outside of FAs. The Riparian
IFS evaluation of the FAs is different because these same in-channel characteristics are
secondary to features and processes that are occurring out-of-channel that define riparian
floodplain community structure (see RSP Section 8.6).
Organizationally, the TM contains seven sections that, in addition to the Introduction (Section 1)
and Objectives (Section 2), include sections aligned with the five objectives noted above.
3. REVIEW OF RIVER STRATIFICATION AND STUDY AREA
SELECTION PROCESS
The proposed Project will affect flows in mainstem and off-channel habitats in the Susitna River
downstream of the dam site at RM 184. In order to characterize the existing and proposed flow
regimes and riverine habitats and organisms, the Susitna River was stratified into geomorphic
reaches based on channel type, gradient, confinement, bed material and tributary confluences.
As noted in Section 8.5.4.1.2 of RSP Section 8.5, the selection of study areas or study sites
represents an important aspect of all resource related studies inasmuch as the sites or areas
studied are those that will ultimately be used for characterizing physical, geomorphological,
chemical and biological resources and for evaluating Project effects. It was therefore
fundamentally important that the logic and rationale for the selection of such areas be clearly
articulated, understood, and agreed to by agencies and licensing participants.
As a result, the RSP proceeded in a series of steps that first described the stratification process
used for the entire river, and then discussed and evaluated various approaches to study site
selection that lead to the identification of specific FAs for intensive study within the Middle
River Segment. For convenience, these steps are presented below to provide context for and as a
precursor to the contemporary habitat mapping statistical analysis.
3.1. River Stratification
As an initial step in the selection process, the Susitna River was stratified into distinct stratum
reflective of certain geomorphic, hydrologic, and physical characteristics shared by each stratum.
1 Note that this TM describes sites and Focus Areas for the Middle River segment only as per January 31, 2013 FERC RSP
delivery schedule received by AEA on January 17, 2013. AEA intends to discuss Lower River Segment study site selection
during the February 14-15, 2013 TWG meetings and will include the Lower River Segment study sites in the March 1, 2013
submittal.
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The number of strata was determined based on the realization that the effects to physical
processes and aquatic resources will be resource type-, location-, and habitat-specific. For
example, at the site scale level, responses of fish habitat to changes in flow are expected to be
different in side sloughs versus mainstem versus side channel versus tributary delta versus
riparian habitats. At a broader scale, e.g., segment, it is plausible that effects to the same
mainstem habitat types will differ depending on location in the river network. In addition, there
will be a cumulative effect running down the length of the Susitna River below the dam.
Importantly, different Project operations will affect different habitats and processes differently,
both spatially and temporally. The habitat and process models will therefore need to be spatially
discrete, at potentially the site/area level, mainstem habitat type level, and segment levels, and
yet able to be integrated to allow for a holistic evaluation of each alternative operational
scenario.
As noted in Section 8.5.3 of the RSP, the study area at issue with respect to Project operations
and flow regulation effects consists of two segments of the river:
Middle River Segment – Susitna River from Watana Dam site to confluence of Chulitna
and Talkeetna rivers (Three Rivers Confluence) (RM 184 to RM 98.5)
Lower River Segment – Susitna River extending below Talkeetna River to mouth (RM
98.5 to RM 0)
The Middle River Segment represents the section of river below the Project dam that is projected
to experience the greatest effects of flow regulation caused by Project operations. Within this
reach, the river flows from Watana Canyon into Devils Canyon, the narrowest and steepest
gradient reach on the Susitna River. The Devils Canyon constriction creates extreme hydraulic
conditions including deep plunge pools, drops, and high velocities. Downstream of Devils
Canyon, the Susitna River widens but remains essentially a single main channel with stable
islands, numerous side channels, and sloughs.
The Lower River Segment receives inflow from three other large river systems. An abrupt,
large-scale change in channel form occurs where the Chulitna and Talkeetna rivers join the
Susitna River near the town of Talkeetna in an area referred to as the Three Rivers Confluence.
The annual flow of the Chulitna River is approximately the same as the Susitna River at the
confluence, though the Chulitna contributes much more sediment than the Susitna. The
Talkeetna River also supplies substantial flow rates and sediment volumes. Farther downriver,
the Susitna River becomes notably more braided, characterized by unstable, shifting gravel bars
and shallow subchannels. The Yentna River is a large tributary to the Lower Susitna River and
supplies about 40 percent of the mean annual flow at the mouth of the Susitna River.
Geomorphic analysis of both the Middle River and Lower River segments confirmed the distinct
variations in geomorphic attributes (e.g., channel gradient, confinement, channel planform types,
and others) (see RSP Section 6.5) and resulted in the classification of the Middle River Segment
into eight geomorphic reaches and the Lower River Segment into six geomorphic reaches (see
Figures 8.5-11 and 8.5-12 of RSP Section 8.5, which for convenience have been included as
Figures 1 and 2 of this TM). These reaches were incorporated into a hierarchical stratification
system that scales from relatively broad to more narrowly defined categories as follows:
Segment → Geomorphic Reach → Mainstem Habitat Type →
Main Channel Mesohabitat Types → Edge Habitat Types
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The highest level category is termed Segment and refers to the Middle River Segment and the
Lower River Segment. The Geomorphic Reach level is next and consists of the eight categories
(MR-1 through MR-8) for the Middle River Segment and six categories (LR-1 through LR-4) for
the Lower River Segment (see RSP Section 6.5.4.1.2.2 and RSP Section 8.5 Table 8.5 4). The
geomorphic reach breaks were based in part on the following five factors: 1) Planform type
(single channel, island/side channel, braided); 2) Confinement (approximate extent of floodplain,
off-channel features); 3) Gradient; 4) Bed material / geology; and 5) Major river confluences.
This level is followed by Mainstem Habitat Types, which capture the same general categories
applied during the 1980s studies but includes additional sub-categories to provide a more refined
delineation of habitat features (see RSP Section 8.5 Table 8.5 5). Major categories and sub-
categories under this level include Main Channel Habitats consisting of Main Channel, Split
Main Channel, Braided Main Channel, Side Channel, and Off-channel Habitats that include Side
Slough, Upland Slough, Backwater and Beaver Complexes; and Tributary Habitats that consist
of the segment of the tributary influenced by mainstem flow. The next level in the hierarchy is
Main Channel and Tributary Mesohabitats, which classifies habitats into categories of Cascades,
Riffle, Pool, Run, and Glide. The mesohabitat level of classification is currently limited to the
main channel and tributary mouths for which the ability to delineate these features is possible via
aerial imagery and videography. As noted in the RSP, mesohabitat mapping in side channel and
slough habitat types will require ground surveys. The last level in the classification is Edge
Habitat and is intended to provide an estimate of the length of shoreline in contact with water
within each habitat unit. The amount of edge habitat within a given habitat unit will provide an
index of habitat complexity, i.e., more complex areas that consist of islands, side channels, etc.
will contain more edge habitat than uniform, single channel areas.
Overall, the goal of the stratification step was to define segments/reaches with effectively similar
characteristics where, ideally, repeated replicate sampling would result in parameter estimates
with similar statistical distributions. The stratification/classification system described above was
designed to provide sufficient partitioning of sources of variation that can be evaluated through
focused study efforts that target each of the habitat types, and from which inferences concerning
habitat–flow responses in unmeasured sites can ultimately be drawn.
3.2. Selection of Study Areas/Study Sites
In general (as noted by Bovee 1982), there are three characteristic approaches to instream flow
studies that pertain to site selection that were considered for application in the Project. These
included representative sites/areas, critical sites/areas, and randomly selected sites/areas.
3.2.1. Representative Sites
Representative sites are those where professional judgment or numerically and/or qualitatively
derived criteria are relied on to select one or more sites/areas that are considered representative
of the stratum or larger river. Representative sites typically contain all habitat types of
importance. In general, the representative site approach can be readily applied to simple, single
thread channel reaches, where the attributes that are measured are extrapolated linearly based on
stream length or area. In this case, the goal of stratification will be to identify river segments that
are relatively homogenous in terms of mesohabitat mixes, and the methods used for stratification
tend to be classification-based. This approach typically requires completing some form of
mapping up front, and using the results to select sites that encompass the range of habitat
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conditions desired. The results of such habitat mapping were not available during the initial
study site/area selection, but since then, the results of the habitat mapping of the Middle River
Segment have been completed and analyzed and are reported on in Section 5 of this TM.
Applicability to the Susitna–Watana Project: Yes – see Section 4 of this TM.
3.2.2. Critical Sites
Critical sites are those where available knowledge indicates that either (i) a sizable fraction of the
target fish population relies on that location, (ii) a particular habitat type(s) is (are) highly
important biologically, or (iii) where a particular habitat type is well known to be influenced by
flow changes in a characteristic way. For example, in the case of the Susitna River, historical
fish studies repeatedly showed the importance of certain side slough, upland slough, and side
channel areas for spawning and juvenile rearing. Critical sites or areas are typically selected
assuming that potential Project effects to other areas are secondary in terms of implications to
fish population structure, health, and size. This assumption can only really be tested if other sites
are identified that are similar looking but were not deemed critical, and sampling is performed on
those sites as well to confirm the critical nature of the sites that were identified as such.
Applicability to the Susitna–Watana Project: Yes, especially with respect to selection of side
channel/side slough/upland slough complexes that have been shown to be influenced by main
channel flows and that are biologically important.
3.2.3. Randomly Located Sites
Randomly located sites are those where sites, areas, or measurement locations are selected
randomly from each defined stratum or habitat type, and replicate sites or cross-sections are
sampled to estimate variance (e.g., Williams, 1996; Payne et al. 2004). Site selection based on
random sampling tends to involve statistical multivariate grouping or stratification approaches,
such as cluster analysis or ordination techniques. The approach is the least subject to potential
for bias, because it relies on distinct rules and algorithms. However, the approach becomes
increasingly difficult to apply in site selection when the sites become more complex, such as is
the case on the Susitna River. In addition, the number of sites will be contingent on the
variability within the universal data set: the greater the number of clusters, the greater the
potential number of sites. Strict random sampling is therefore not likely applicable for
evaluating off-channel habitats and sloughs where the morphology of multiple channels varies
substantially and in complex ways within and across sites.
Applicability to the Susitna–Watana Project: Yes, but more appropriate with respect to main
channel mesohabitat sampling (i.e., riffle, run, glide, pool) or selection of mainstem habitat types
for Habitat Suitability Criteria (HSC) sampling.
3.2.4. Focus Areas
During the September 11, 2012, Technical Workgroup (TWG) meeting, the concept of
“intensive study areas” was introduced and discussed. This concept evolved around the
realization that a prerequisite to determining the effects of Project development and operations
on the Susitna River is the need to first develop an understanding of the basic physical, chemical
and ecological processes of the river, their interrelationships, and their relationships with flow.
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Two general paths of investigation were considered, 1) process and resource specific and 2)
process and resource interrelated. Under the first, process and resource specific, studies would
focus on determining relationships of flow with specific resource areas (e.g., water quality,
habitat, ice, groundwater, etc.) and at specific locations of the river without considering
interdependencies of other resource areas at different locations. Under the second, process and
resource interrelated, studies would be concentrated at specific locations of the river that would
be investigated across resource disciplines with the goal of providing an overall understanding of
interrelationships of river flow dynamics on the physical, chemical, and biological factors that
influence fish habitat.
Because the flow dynamics of the Susitna River are complex, it was reasoned that concentrating
study efforts across resource disciplines within specific locations would provide the best
opportunity for understanding flow interactions and evaluating potential Project effects and
therefore major emphasis was placed on selecting those areas, which were termed Focus Areas
(FA). However, it was also reasoned that there will be a need to collect information and data
from other locations to meet specific resource objectives. As a result, the study site/area
selection process presented in the RSP actually represents a combination of both approaches that
includes sampling within specified FAs as well as sampling outside of FAs (see Section 3.2.5 for
discussion of sites outside of FAs).
Composition wise, the FAs contain combinations of different habitat types and features as
characterized according to the hierarchical classification system noted above that may function
and respond differently or similarly (compared to other areas) to changes in flow depending on
flow timing, magnitude, duration, etc., and their interrelationships with each other and other
resource processes. Thus, these areas would be the focus of concentrated studies across
disciplines enabling an integrated assessment of resource characteristics and processes and
providing a more meaningful understanding of resource interrelationships and how flow
regulation would influence these. This approach of concentrating study efforts within selected
areas should allow for a more comprehensive evaluation of Project effects on the different
resources, than if such features were evaluated solely in isolation resulting in a more fragmented
analysis.
As noted in the RSP, the FA concept represents a combination of all three of the study site
selection methods described above, inasmuch as (1) the areas would contain habitat types
representative of other areas; (2) the areas would include certain habitat types repeatedly used by
fish and therefore can be considered “critical areas”; and (3) sampling of certain habitat features
or mesohabitat types within the areas would be best approached via random sampling. Since the
RSP, results of the habitat mapping of the Middle River Segment have been completed which
has allowed for an evaluation of the “representativeness” of the habitat types within the ten FAs
described below, compared to areas outside of the FAs. Results of that analysis are presented in
Section 5.
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4. FOCUS AREAS AND STUDY SITES IDENTIFIED IN THE IFS RSP
4.1. Focus Areas
The RSP identified and described 10 FAs that had been discussed with the TWG and were
originally proposed for detailed study within the Middle River Segment. Locations of the FAs
are depicted in Figure 1 and their specific characteristics and rationale for selection were
described in RSP Section 8.5 Table 8.5.6, which for convenience has been included as Table 1 of
this TM. Schematic photos of each of the areas were likewise depicted in RSP 8.5 as Figures
8.5-13 through Figure 8.5-22 reproduced herein as Figures 3 through 12. The 10 FAs were
intended to serve as specific geographic areas of the river that will be the subject of intensive
investigation by multiple resource disciplines including Fish and Aquatics Instream Flow,
Riparian Instream Flow (see Section 8.6), Groundwater (see Section 7.5), Geomorphology (see
Section 6.0), Ice Processes (see Section 7.6), Water Quality (see Section 5.0), and Fish
Distribution and Abundance in the Middle/Lower River (see RSP Section 9.6). The FAs were
selected during an inter-disciplinary resource meeting that involved a systematic review of aerial
imagery within each of the Geomorphic Reaches (MR-1 through MR-8) for the entire Middle
River Segment. Focus Areas were selected within Geomorphic Reach MR-1 (one Focus Area),
Geomorphic Reach MR-2 (two Focus Areas), Geomorphic Reach MR-5 (one Focus Area),
Geomorphic Reach MR-6 (four Focus Areas), Geomorphic Reach MR-7 (one Focus Area), and
Geomorphic Reach MR-8 (one Focus Area). FAs were not selected for Geomorphic Reaches
MR-3 or MR-4 due to safety considerations related to Devils Canyon.
The FAs were those deemed representative of the major features within each geomorphic reach
and included mainstem habitat types of known biological significance (i.e., where fish have been
observed based on previous and/or contemporary studies), as well as some locations (e.g.,
Slough 17) where previous sampling revealed few/no fish. The FAs were assumed to have
included side channels, side sloughs, upland sloughs, and tributary mouths that were
representative of these habitat types in other portions of the river. This assumption has now been
evaluated based on the results of the habitat mapping and is discussed in Section 6 of this TM.
Three of the Focus Areas in Geomorphic Reach MR-6 and one in Geomorphic Reach MR-8
contain specific habitat types that were found, during the 1980s studies, to be consistently used
by salmon for spawning and/or rearing. These areas included Slough 21, Slough 11, and Skull
Creek in Geomorphic Reach MR-6 and Whiskers Slough in Geomorphic Reach MR-8. Overall,
92 percent of the sockeye, 70 percent of the chum, and 44 percent of the slough-spawning pink
salmon were found in just these four sloughs. By definition, these areas represent “critical areas”
and were included in the FAs to allow some comparisons with the 1980s data. The upper three
FAs (one in Geomorphic Reach MR-1 and two in Geomorphic Reach MR-2) were selected based
on their representativeness of the respective geomorphic reaches and the inclusion of a mix of
side channel and slough habitat types. However, there is no existing fish information on these
areas because they were not sampled in the 1980s. Nominally, the FAs range in length from 0.5
mile to 1.9 miles (Table 1).
Selection criteria for the FAs considered the following:
All major habitat types (main channel, side channel, side slough, upland slough, tributary
delta) will be sampled within each geomorphic reach.
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At least one (and up to three) FA(s) per geomorphic reach (excepting geomorphic reaches
associated with Devils Canyon – MR-3 and MR-4) will be studied that is/are
representative of other areas.
A replicate sampling strategy will be used for measuring habitat types within each FA,
which will include a random selection process of mesohabitat types.
Areas that are known (based on existing and contemporary data) to be biologically
important for salmon spawning/rearing in mainstem and lateral habitats will be sampled
(i.e., critical areas).
Some areas for which little or no fish use has been documented or for which information
on fish use is lacking will also be sampled.
It is important to note that the FA concept and approach will work for the Middle River Segment
since the main channel is relatively confined. However, below the Three Rivers Confluence
where the Chulitna and Talkeetna rivers enter, the Susitna River main channel widens and
becomes heavily braided and therefore the same FA approach, which includes measurement of
the entire main channel, would not be applicable in the Lower River Segment. Rather, the
selection of study sites/areas there will be more targeted to specific biologically important and
representative habitat features, such as tributary mouths, side and upland sloughs, and side
channels. More details describing the general approach that will be used in selecting study sites
in the Lower River Segment will be presented during the February 14, 2013 TWG meeting and
described further in the March 1, 2013 Final Focus Area TM.
4.2. Sites Outside of the Focus Areas
The boundaries of the FAs do not limit the geographic extent of other studies, as many other
study sites and areas already have been or will be located as part of resource specific
investigations. Indeed, other resource studies have identified study sites outside of FAs as
necessary to achieve specific resource study goals and objectives (see Fisheries (RSP Section
9.6, 9.8, and 9.9), Groundwater (RSP Section 7.5), Geomorphology (RSP Section 6.0), Ice
Processes (RSP Section 7.6), and Water Quality (RSP Section 5.0). Fisheries studies for
example, have and will be conducted in multiple locations both within and outside of FAs as a
means to fully characterize fish distributions in the Middle and Lower River segments (see Draft
Fish Distribution and Abundance Implementation Plan for Study 9.6 (R2 2013). In addition, the
salmon escapement studies will be monitoring fish movements within a 184-mile section of the
river extending from RM 22 and extending upstream to Kosina Creek at RM 206.8. In addition,
17 fixed telemetry stations will be installed within a mixture of tributaries and slough habitats at
locations throughout the entire length of the river. Water quality studies will likewise occur at
locations within and outside of FAs. A total of 39 water quality monitoring stations have been
identified that extend from RM 15.1 to RM 233.4. These sites will be used for collection of
baseline water quality data. In addition, water quality sampling will be conducted in selected
FAs to provide a more detailed characterization of water quality characteristics in those areas as
they relate to fish productivity and main channel flow conditions (see RSP Section 5). Fluvial
geomorphology studies involving sediment transport and large woody debris distribution
likewise include areas both within and outside of FAs, as do the Ice Processes studies. The Ice
Processes studies include time-lapse photography at more than 25 sites in the river extending
from RM 11 to RM 223, as well as winter discharge measurements at selected cross-sections,
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and winter field studies of FAs as a means to understand how winter conditions affect fish
habitats and geomorphology.
In terms of the IFS, there are a total of 80 cross-sectional transects in the Middle River Segment
and 8 transects in the Lower River Segment that have been established and flow data collected to
support development of the open-water flow routing model (see Open-water Flow Routing
Model Results TM [R2 2013], and RSP Section 8.5.4.3 and Table 8.5-7 reproduced herein as
Table 2). These transects were primarily located across single thread sections of the river;
however, some do extend across more complex sections. In most cases, two to three sets of flow
measurements have been made at each transect. The resulting data sets can be used, at a
minimum, for evaluating velocity-depth distributions across the channel that can be related to
biologically relevant criteria associated with various life stage requirements (e.g., spawning,
adult holding, juvenile rearing). In many cases (pending review of the cross-sectional data), it
should be possible to develop actual habitat-flow relationships following a 1-D PHABSIM type
analysis (see RSP Section 8.5.4.6). The cross-sectional transects represent an important dataset
that can be used to characterize habitat-flow response characteristics of the main channel of the
Susitna River. These types of data were never collected during the 1980s studies and no main
channel habitat-flow relationships were developed. Importantly, now that the main channel
habitat mapping is completed (see Section 6), the transect locations have been assigned to
specific mainstem habitat types (main channel, side channel, split channel, etc.) and main
channel mesohabitat types (e.g., riffle, run, glide, pool) and can be randomly selected for
analysis. These additional transects may also be useful for extrapolating results/relationships
from measured to unmeasured sites (see RSP Section 8.5.4.7).
As noted in the RSP, results of the 2013 studies will be carefully reviewed and evaluated, and
will likely result in some refinements to existing study sites/areas and/or establishment of
supplemental sites that target specific habitat-flow relationship types. For example, the scaling
up/expansion of flow – habitat relationships derived from measured to unmeasured sites or
locations within the river will likely require measurement of certain flow attributes (e.g.,
determination of the relationships of main channel flow to side channel and side slough
breaching flows; defining areas of turbid/non-turbid waters; defining areas of groundwater
upwelling) at unmeasured areas. The point is that the study sites/areas presented in RSP Section
8.5 and in other resource RSPs are subject to refinement based on results of 2013 investigations
and study needs.
5. HABITAT MAPPING ANALYSIS
Habitat mapping of the Middle River Segment of the Susitna River was completed using a
combination of geo-rectified aerial imagery (2011 Matsu Ortho Imagery at 1:8000 scale.
http://matsu.gina.alaska.edu/wms/imagery) in combination with High Definition aerial
videography that was taken of the river in August 2012 (≈ 10,000 cfs) (HDR 2013). The results
of the habitat mapping provided a spatial depiction of the distribution of habitat types and
features throughout the entire length of the Middle River Segment. Specific habitat types were
digitized using ARC GIS and lineal distances computed of each discrete habitat feature. Results
of the habitat mapping were used to evaluate the “representativeness” of the Focus Areas with
respect to other areas of the river. In this context, representativeness specifically refers to how
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well habitat units within the FAs represent habitat units outside of these areas within the same
geomorphic reach.
There are multiple ways to examine or measure representativeness of the FAs but the most
valuable examination will occur after the first year of sampling when more direct information
will have been obtained of the existing habitat types from field work. However, at the current
planning stage of the study, representativeness was examined by 1) comparing the representation
of habitat types within the FAs to the representation of habitat types in the entire geomorphic
reach; 2) determining if the habitat types have been proportionately represented (focus vs. non-
focus areas); 3) determining if there was a bias in the habitat types that were selected in the FAs;
and 4) evaluating whether a random systematic approach in the selection of FAs would yield
different results than the selection process and criteria applied to the current FAs.
5.1. Methods
The methods used in completing the habitat mapping analysis are described below.
5.1.1. Habitat Data Compilation and Review
The overall objective of Middle River Segment mainstem mapping was to characterize and
classify river habitat in the mainstem from the proposed Watana Dam site to the Chulitna River
confluence. These data were used to evaluate the selection of FAs for the IFS studies (this TM)
as well as to develop a study site selection approach for the fish distribution and abundance
studies (see Draft Fish Distribution and Abundance Implementation Plan for Study 9.6 [R2
2013]). The mapping effort also included tributaries extending 0.5 miles upstream from the
confluence with the mainstem. The 0.5 mile extent was used because it was considered a
conservative standard that is greater than the expected hydrologic influence. The actual
hydrologic influence is currently not known.
As a preliminary step in the analysis, the results of the GIS based habitat mapping were
presented and discussed during an IFS internal technical review meeting. Habitat mapping
generally followed the hierarchical and nested classification system developed specifically for
the Susitna River that was described above. Digital mapping results were displayed and
reviewed with technical staff who had been in the field and were familiar with channel
characteristics. The review process proceeded from the upper to lower geomorphic reaches and
resulted in a number of modifications to the habitat types. These modifications were
subsequently made and a final draft database of habitat mapping results developed. Overall, the
geo-rectified imagery in combination with aerial videography was sufficient to map the Middle
River Segment mainstem habitat to the mesohabitat level. However, the imagery was not
suitable for mapping off-channel or tributary habitats to this level; mapping of these features will
require field surveys.
5.1.2. Evaluation of Representativeness – Representation and Proportionality
The habitat classifications can be summarized by counts or lengths of identified units inside and
outside of FAs. However, the length of river that is included in FAs is less than that not included
in the FAs, so some scaling of counts and lengths is necessary for proportional comparisons. A
suite of scaled metrics were identified and developed that were used in a comparative analysis of
the representativeness of habitat types within and outside of FAs. These metrics included the
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major habitat categories specified in the classification and consisted of percentages or,
proportions of lineal distances, and densities (length per mile) (Table 3).
These metrics are compared graphically. There are two bases for comparison: 1) is each habitat
type contained in the geomorphic reach represented in FAs within the reach; and 2) is the
representation proportional. The metrics cannot be statistically compared within geomorphic
reaches (focus area vs. non-focus area) because they do not represent independent random
samples. Thus, there is no estimation of variance available.
5.1.3. Evaluation of Representativeness – Bias
Statisticians define the representativeness of samples based on the absence of bias. Statistical
bias is a consistent under- or over- estimation of a known population parameter. In this
application, bias could exist if the FAs are consistently over sampling braided main channels, for
example. For model inferences specific to habitat units, bias in proportional sampling is not a
large issue. However, if selected samples for any particular part of the program not related to the
instream flow-habitat models are used to make inference to entire geomorphic reaches, this
selection bias could result in estimation bias.
In this analysis, bias in the selection method was examined by considering the geomorphic
reaches as independent replicates of potential bias, and testing if the average bias is different
from zero using a t-test or a non-parametric equivalent. For example, if the FAs selection has
consistently under-represented upland sloughs, this analysis would highlight that result.
5.2. Results
5.2.1. Habitat Data Compilation and Review
Results of the habitat mapping as presented and summarized in HDR (2013) indicated that the
main channel habitats within the Middle River Segment of the Susitna River varied by
geomorphic reach and generally increased in complexity moving from the upper end of the
segment to downstream locations (Table 4). Mesohabitat in the main channel was generally
dominated by a mixture of run and glide habitats (Table 5). Glide and run habitats were not
distinguished from each other at this level of classification and included smooth-flowing, low
turbulence reaches as well as areas with some standing or wind waves and occasional solitary
protruding boulders. Run-glide mesohabitat dominated all reaches except MR-4, the reach
where Devils Canyon is located. Riffle habitat was most prevalent in MR-4. Riffle habitat was
lacking or only found in small amounts in the other Middle River Segment geomorphic reaches.
Side channels were predominantly glide or run, with some riffle areas in the lower reaches
(Table 5). Many side channels were not completely inundated with flowing water and so
identification of riffle or run habitat was not possible; these were classified as unidentified and
were most prevalent in MR-6.
Cascade habitat was not found within any Middle River Segment geomorphic reach. The
geomorphic reach through Devils Canyon (MR-4) contained the only rapids in the Middle River
Segment, which accounted for 38% of the mainstem habitat in that reach. Only 3 pools were
found in the Middle River Segment and these were also contained in MR-4 between rapids in
Devils Canyon.
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The habitat associated with the confluence of tributaries with the main channel river was
documented as tributary mouth and clear water plume. Not all tributaries that entered the Middle
River had tributary mouth habitat. Small tributaries where the vegetation line was close to the
mainstem did not fan out and create the areas classified as tributary mouth habitat. In addition,
small tributaries or tributaries that flowed into fast moving or turbulent sections of the mainstem
did not produce clear water plume habitats. Clear water plume habitats were located in reaches
MR-2, MR-3, MR-5, and MR-7, with the most being in reach MR-2.
Off-channel habitat was assigned to one of three habitat types observed: upland sloughs, side
sloughs, and backwaters. Upland and side sloughs were prevalent throughout the Middle River
reaches outside of Devils Canyon and downstream of the uppermost reach at MR-1 (Table 6).
Side sloughs were most abundant in MR-5, followed by MR-6. Upland sloughs were most
abundant in MR-8, and generally increased in abundance towards the downstream reaches.
Beaver complexes always were associated with slough habitats and as such were not categorized
as a habitat type but were noted as a characteristic of that slough habitat unit. Beaver dams were
rarely present in side slough habitat, and slightly more prevalent in upland sloughs. Beaver dams
were only observed in reaches MR-5, MR-6 and MR-7.
Backwater habitat was also relatively rare and found in a few areas in the lower reaches from
MR-5 through MR-8. A single backwater was also delineated in MR-2 and MR-4, but accounted
for less than 1 percent of the linear habitat in that reach due to small size. The greatest total area
of backwater habitat was in MR-6.
5.2.2. Evaluation of Representativeness
5.2.2.1. Representation and Proportionality
The FAs have captured the majority of habitat types represented in each geomorphic reach.
Below, the proportionality metrics are graphically displayed and discussed and the minor cases
where FAs may have fallen short of representativeness described.
Main channel proportionality metrics are displayed graphically in Figure 5.1. MR-1 is all single
main channel. MR-2, MR-5 and MR-6 have a small amount of split main channel, which is not
represented within the FA. In MR-7, the split main channel is represented, but at a higher
proportion than exists in the full reach. In MR-8, the braided main channel is not represented in
the FA.
Side channels and sloughs proportionality metrics are displayed graphically in Figure 5.2. MR-1
side channels appear to be represented proportionately. MR-2 FAs contain all habitats, with a
higher portion of side slough than the full reach. MR-5 side channels and side sloughs are not
represented in FAs. MR-7 side sloughs are not represented in FAs, and upland sloughs are
proportionally higher in FAs than in the total reach. In MR-8, all habitats are represented in the
FAs, but there is proportionately more side slough habitat than in the reach at large.
Beaver complex proportionality is displayed in Figure 5.3. Beaver habitat is represented in MR-
6 at a higher proportionality in FAs than without. In MR-7, existing beaver habitat in the reach
is not represented in the FA.
Backwater and tributary-related habitat counts and proportionality are both displayed in Figure
5.4. MR-1 does not contain these habitat types. In MR-2, identified plumes and backwaters are
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not represented in FAs, and tributaries are proportionately under-represented. In MR-5, there is
only one tributary with a mouth and plume, and it is contained in the FA. In MR-6, all habitats
are represented, but tributaries are not proportionately represented. In MR-7, identified tributary
mouths and plumes are not represented. In MR-8, the single backwater is not in the FA, but the
two tributaries are both in the FA.
The main channel mesohabitat comparison is shown in Figure 5.5. MR-1 is all glide/run habitat.
MR-2 and MR-5 have a small amount of identified riffle that is not represented in the FAs. The
other reaches are generally well represented.
It should be noted that tributary and tributary features (mouths and plumes) are subject to some
interpretation from aerial photos, and depend upon flow. As a result, tributaries were further
classified based on the habitat mapping and other sources to identify potential fish bearing
tributaries that should be considered for sampling in the Middle River. Table 7 shows the counts
of potential tributaries by geomorphic reach and focus area vs. non-focus area. This table shows
that tributaries may still be under-represented in FAs, but not by as large a margin as the habitat
mapping results indicated.
5.2.2.2. Bias
Bias estimates are displayed in Table 8. A negative number in this table indicates that a habitat
was over-represented in the Focus Areas, and a positive number indicates that a habitat was
under-represented. There is a fairly even distribution of cases where habitat was under-
represented and over-represented across reaches. Thus, there is no strong evidence (i.e., no
statistically significant results at an alpha level of 0.10) of bias in the habitat types that were
selected within the FAs. Tributary mouths were consistently under-represented, however (p-
value = 0.10). Overall, these results indicate there was no obvious systematic bias in the
selection of FAs.
6. IMPLICATIONS OF HABITAT MAPPING RESULTS AND STUDY
AREA REFINEMENTS
The results of the habitat mapping analysis have provided insight into the types and distributions
of habitats present in the Middle River Segment of the Susitna River. This information and the
GIS mapping layers that have been generated and provided in HDR (2013) have been useful for
evaluating the representativeness of the original Focus Areas presented in the IFS RSP. Results
of that analysis have addressed the following questions:
1. Are the Focus Areas representative of areas and habitat types within the entire Middle
River Segment?
Answer: Yes – the combined FAs contain one or more of the habitat types and features
found within areas outside of the FAs in the Middle River Segment.
2. Are the Focus Areas within a given Geomorphic Reach representative of areas and
habitat types found within other portions of the same Geomorphic Reach?
Answer: In general, Yes – in most instances the FAs within a given Geomorphic Reach
contain one or more of the habitat types and features found within other portions of the
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same Geomorphic Reach. However, there were a few exceptions primarily related to the
absence of certain main channel habitat types (i.e., split main channel and braided
channel) from within FAs. Two off-channel habitat types were likewise absent from
within certain FAs; side channels and side sloughs in MR-5 and side sloughs found in
MR-7 are not represented in the respective FAs. Consideration will be given to either
adjusting the length of the FAs to capture the respective habitat types or simply
identifying and adding discrete sites that include these habitat types that are outside of the
FAs.
3. Are there certain habitat types detected as part of the habitat mapping that warrant special
consideration relative to sampling?
Answer: Yes – very few backwater habitats were detected within the entire Middle River
Segment and none are included in FAs within MR-2 or MR-8. Likewise, relatively few
tributary plume areas were identified in the segment and again, none were included in
FAs within MR-2 and MR-8 even though present within those reaches. These habitats
are important to fish and therefore consideration will be given to adding sites specifically
targeting backwater and tributary plume habitats.
4. Was there a detectable bias in the way in which the FAs were selected?
Answer: No – results of the analysis did not indicate any systematic bias in terms of the
FAs selected and the habitat types they contain.
5. What about the habitat types that have not been included in the FAs but are represented in
the Geomorphic Reaches? Should those be sampled?
Answer: Yes – if those habitat types are not already captured by the cross-sectional
transects located outside of the FAs, then consideration will be given to locating and
adding discrete habitat types to ensure they are captured and measured within a given
Geomorphic Reach. Table 9 shows the habitat types that are represented by FAs, cross-
sections and those that are still needed.
6. Based on the results of the habitat mapping and subsequent analysis of representativeness
of the FAs, is there a need to establish additional Focus Areas within any of the
Geomorphic Reaches?
Answer: No – the existing FAs, with a few exceptions relative to specific habitat types
noted in 2 and 3 above, capture the habitat characteristics and diversity of a given
Geomorphic Reach.
7. FINAL LISTING OF FOCUS AREAS AND STUDY SITES
The results of the habitat mapping analysis indicate that the FAs identified in the IFS Fish and
Aquatic RSP (RSP Section 8.5) are generally representative of habitat types found in other
portions of the river. Those FAs should be finalized for study in 2013 in accordance with the
respective resource specific RSPs. Those FAs, coupled with the existing sites (i.e., cross-
sections) that have been established outside of the FAs, the study sites outside of the FAs that
have been identified as part of other resource studies, as well as a few supplemental sites (to be
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determined and presented during the February 14, 2013 TWG) that will be added in 2013 to fill-
in specific habitat types missing from certain FAs, will collectively provide a comprehensive and
spatially expansive array of study areas and sites within the Middle River Segment of the Susitna
River.
8. REFERENCES
AEA (Alaska Energy Authority). 2011. Pre-Application Document. Susitna-Watana
Hydroelectric Project FERC Project No. 14241. Alaska Energy Authority, Anchorage,
Alaska.
Bovee, K. 1982. A guide to stream habitat analysis using the instream flow incremental
methodology. U.S. Fish and Wildlife Service. FWS/OBS - 82/26.
HDR. 2013. Middle Susitna River Segment remote line habitat mapping technical memo.
Prepared for Alaska Energy Authority, Anchorage, Alaska.
Payne, T.R., S.D. Eggers, and D.B. Parkinson. 2004. The Number of Transects Required to
Compute a Robust PHABSIM Habitat Index. Hydroecol Appl. 14(1): 458-465.
R2 Resource Consultants. 2013. Draft Susitna River Fish Distribution and Abundance
Implementation Plan. Prepared for Alaska Energy Authority. January 2013.
R2 Resource Consultants, GW Scientific, Brailey Hydrologic, and Geovera. 2013. Open-water
HEC-RAS flow routing model. Prepared for Alaska Energy Authority. January 2013.
Williams, J.G. 1996. Lost in space: minimum confidence intervals for idealized PHABSIM
studies. Transactions of the American Fisheries Society. 125: 458-465.
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9. TABLES
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 17 January 31, 2013 Table 1. Locations, descriptions and selection rationale of proposed Focus Areas for detailed study in the Middle River Segment of the Susitna River. Focus Area identification numbers (e.g., Focus Area 184) represent the truncated Project River Mile (PRM) at the downstream end of each Focus Area. Focus Area ID Common Name Description Geomorphic Reach Location (PRM) Area Length (mi) Habitat Types Present Fish use in 1980s Instream Flow Studies in 1980s Rationale for Selection Main Channel, Single Main Channel, Split Side Channel Tributary Mouth Side Slough Upland Slough Beaver Complex Upstream Downstream Spawning Rearing IFG DIHAB RJHAB Focus Area-184 Watana Dam Area approximately 1.4 miles downstream of dam site MR-1 185.7 184.7 1.0 X X X N/A N/A N/A N/A N/A Focus Area-184 length comprises 50% of MR-1 reach length (2 miles long) and contains split main channel and side channel habitat present in this reach. Focus Area-173 Stephan Lake, Complex Channel Wide channel near Stephan Lake with complex of side channels MR-2 175.4 173.6 1.8 X X X X N/A N/A N/A N/A N/A Focus Area-173 contains a complex of main channel and off-channel habitats within wide floodplain. Represents greatest channel complexity within MR-2. Reach MR-2 is 15.5 miles long and channel is generally straight with few side channels and moderate floodplain width (2-3 main channel widths). Focus Area-171 Stephan Lake, Simple Channel Area with single side channel and vegetated island near Stephan Lake MR-2 173.0 171.6 1.4 X X X N/A N/A N/A N/A N/A The single main channel with wide bars, single side channel and moderate floodplain channel width in Focus Area-171 are characteristic of MR-2. Reach MR-2 channel morphology is generally straight with few side channels and moderate floodplain width (2-3 main channel widths). Focus Area-151 Portage Creek Single channel area at Portage Creek confluence MR-5 152.3 151.8 0.5 X X X X Focus Area-151 is a single main channel and thus representative of the confined Reach MR-5. Portage Creek is a primary tributary of the Middle Segment and the confluence supports high fish use. Focus Area-144 Side Channel 21 Side channel and side slough complex approximately 2.3 miles upstream Indian River MR-6 145.7 144.4 1.3 X X X X X X X X X Focus Area-144 contains a wide range of main channel and off-channel habitats, which are common features of Reach MR-6. Side Channel 21 is a primary salmon spawning area. Reach MR-6 is 26 miles long (30% of Middle Segment length) and is characterized by a wide floodplain and complex channel morphology with frequent channel splits and side channels. Focus Area-141 Indian River Area covering Indian River and upstream channel complex MR-6 143.4 141.8 1.6 X X X X X X X X X Focus Area-141 includes the Indian River confluence, which is a primary Middle Susitna River tributary, and a range of main channel and off-channel habitats. Channel and habitat types present in Focus Area-141 are typical of complex Reach MR-6. High fish use of the Indian River mouth has been documented and DIHAB modeling was performed in main channel areas. Focus Area-138 Gold Creek Channel complex including Side Channel 11 and Slough 11 MR-6 140.0 138.7 1.3 X X X X X X X X X The Focus Area-138 primary feature is a complex of side channel, side slough and upland slough habitats, each of which support high adult and juvenile fish use. Complex channel structure of Focus Area-138 is characteristic of Reach MR-6. IFG modeling was performed in side channel habitats. Focus Area-128 Skull Creek Complex Channel complex including Slough 8A and Skull Creek side channel MR-6 129.7 128.1 1.6 X X X X X X X X X Focus Area-128 consists of side channel, side slough and tributary confluence habitat features that are characteristic of the braided MR-6 reach. Side channel and side slough habitats support high juvenile and adult fish use and habitat modeling was completed in side channel and side slough habitats. Focus Area-115 Lane Creek Area 0.6 miles downstream of Lane Creek, including Upland Slough 6A MR-7 116.5 115.3 1.2 X X X X X X X X Focus Area-115 contains side channel and upland slough habitats that are representative of MR-7. Reach MR-7 is a narrow reach with few braided channel habitats. Upland Slough 6A is a primary habitat for juvenile fish and habitat modeling was done in side channel and upland slough areas. Focus Area-104 Whiskers Slough Whiskers Slough Complex MR-8 106.0 104.8 1.2 X X X X X X X X X X X Focus Area-104 contains diverse range of habitat, which is characteristic of the braided, unconfined Reach MR-8. Focus Area-104 habitats support juvenile and adult fish use and a range of habitat modeling methods were used in side channel and side slough areas.
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Table 2. Partial list of river cross-sections, and flow and water surface elevations measured in 2012 on the Susitna River
between River Miles 75 and 184. The list does not include additional measurements in late September/October. Those
measurements had not been processed at the time this study plan was prepared.
Project
River Mile
High Q Trip Mid Q Trip Low Q Trip
Date Time Discharge Date Time Discharge Date Time Discharge
PRM 225.0 6/14/12 17:57 26,932 8/9/12 15:03 11,260 -- -- --
PRM 187.2 6/17/12 16:30 27,698 8/6/12 16:13 14,707 9/15/12 13:17 7,838
PRM 186.2 6/18/12 14:13 24,493 8/6/12 17:05 14,419 9/15/12 14:05 7,630
PRM 185.5 6/18/12 16:10 25,389 -- -- -- -- -- --
PRM 185.2 6/19/12 13:00 26,676 -- -- -- -- -- --
PRM 184.9 6/19/12 15:49 27,619 8/6/12 18:24 14,239 9/15/12 14:57 7,714
PRM 184.4 6/19/12 16:51 27,886 8/7/12 12:38 14,775 9/15/12 15:52 8,353
PRM 183.3 6/20/12 13:19 29,426 8/7/12 13:35 14,183 9/15/12 16:41 8,310
PRM 182.9 6/20/12 16:01 29,218 -- -- -- -- -- --
PRM 181.6 6/20/12 17:56 29,645 8/7/12 14:44 14,705 9/15/12 17:55 8,689
PRM 179.5 6/21/12 12:28 30,866 8/7/12 15:41 14,345 9/14/12 17:05 8,361
PRM 178.5 6/16/12 18:35 29,756 8/7/12 16:37 14,799 9/14/12 17:47 8,738
PRM 176.5 6/21/12 14:40 31,240 8/8/12 12:07 14,559 9/16/12 14:50 10,768
PRM 174.9 6/21/12 16:12 31,163 -- -- -- -- -- --
PRM 173.1 6/21/12 17:39 30,571 -- -- -- 9/16/12 16:29 11,082
PRM 170.1 6/22/12 12:56 31,121 8/8/12 15:16 14,568 9/16/12 17:33 11,137
PRM 168.1 6/22/12 14:33 32,265 8/8/12 16:03 14,655 9/17/12 15:19 14,619
PRM 153.7 6/25/12 17:15 32,162 8/10/12 15:03 14,588 -- -- --
PRM 152.9 6/26/12 13:43 30,487 -- -- -- -- -- --
PRM 152.1 6/26/12 15:38 30,036 8/10/12 16:07 15,351 9/29/12 15:20 18,488
PRM 151.1 6/25/12 14:00 33,180 -- -- -- -- -- --
PRM 148.3 6/26/12 18:24 32,114 8/10/12 18:03 14,941 -- -- --
PRM 146.6 6/27/12 12:24 31,030 -- -- -- -- -- --
PRM 145.7 6/27/12 13:51 31,396 8/12/12 13:12 17,354 9/29/12 16:51 18,131
PRM 145.5 6/27/12 14:40 31,868 -- -- -- -- -- --
PRM 144.9 6/27/12 17:01 31,949 -- -- -- -- -- --
PRM 144.3 6/27/12 18:50 31,121 -- -- -- -- -- --
PRM 143.5 6/28/12 12:17 30,330 8/12/12 14:58 17,006 -- -- --
PRM 143.0 6/28/12 13:53 29,492 -- -- -- -- -- --
PRM 142.2 6/28/12 15:15 29,753 8/12/12 16:29 16,798 9/29/12 17:45 18,301
PRM 141.9 6/28/12 16:27 30,583 8/12/12 17:13 16,803 -- -- --
PRM 141.7 6/28/12 17:41 30,555 -- -- -- -- -- --
PRM 140.0 6/29/12 14:48 30,378 8/13/12 12:54 16,350 9/30/12 13:56 17,619
PRM 139.8 6/29/12 16:21 30,378 -- -- -- -- -- --
PRM 139.0 6/30/12 13:56 28,039 8/13/12 13:58 16,449 -- -- --
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Project
River Mile
High Q Trip Mid Q Trip Low Q Trip
Date Time Discharge Date Time Discharge Date Time Discharge
PRM 138.7 6/30/12 14:51 28,230 8/13/12 14:48 16,344 -- -- --
PRM 138.1 6/30/12 16:33 28,203 -- -- -- -- -- --
PRM 137.6 6/30/12 18:13 27,893 8/13/12 16:14 16,409 9/30/12 15:00 17,382
PRM 136.7 7/1/12 13:35 26,756 -- -- -- -- -- --
PRM 136.2 7/1/12 16:06 26,943 -- -- -- -- -- --
PRM 135.0 7/1/12 18:33 26,526 8/13/12 17:41 15,627 -- -- --
PRM 134.3 7/2/12 12:16 25,463 -- -- -- 10/1/12 13:40 15,568
PRM 134.1 7/2/12 13:18 26,166 8/14/12 13:14 16,491 -- -- --
PRM 133.8 7/2/12 14:30 25,715 8/14/12 14:05 16,275 -- -- --
PRM 133.3 7/2/12 16:22 25,678 -- -- -- -- -- --
PRM 132.6 7/2/12 17:57 25,046 8/14/12 15:17 16,039 -- -- --
PRM 131.4 7/3/12 22:08 28,628 -- -- -- -- -- --
PRM 129.7 7/3/12 17:33 28,243 8/14/12 17:00 16,330 10/1/12 16:16 15,731
PRM 128.1 7/4/12 15:40 26,748 8/15/12 12:50 15,926 -- -- --
PRM 126.8 7/4/12 17:22 27,608 8/15/12 13:40 16,078 10/1/12 17:02 15,582
PRM 126.1 7/5/12 14:24 27,248 -- -- -- -- -- --
PRM 125.4 7/5/12 16:38 26,427 -- -- -- -- -- --
PRM 124.1 7/5/12 18:11 26,132 8/15/12 14:27 16,161 10/1/12 17:42 15,582
PRM 123.7 7/6/12 12:18 23,875 -- -- -- -- -- --
PRM 122.7 7/6/12 14:23 23,331 -- -- -- -- -- --
PRM 122.6 7/6/12 15:59 22,890 8/15/12 16:13 16,287 -- -- --
PRM 120.7 7/6/12 17:19 22,687 -- -- -- -- -- --
PRM 119.9 7/7/12 12:19 20,715 8/16/12 12:54 16,005 10/3/12 14:47 13,998
PRM 118.4 7/7/12 14:06 20,656 -- -- -- -- -- --
PRM 117.4 7/7/12 16:15 20,747 -- -- -- -- -- --
PRM 116.6 7/7/12 17:36 20,665 8/16/12 14:15 16,136 10/3/12 15:53 14,323
PRM 116.3 7/8/12 12:42 23,766 -- -- -- -- -- --
PRM 115.7 7/8/12 14:05 25,006 -- -- -- -- -- --
PRM 115.4 7/8/12 16:13 25,958 -- -- -- -- -- --
PRM 114.4 7/8/12 18:29 25,860 -- -- -- -- -- --
PRM 113.6 7/9/12 14:23 28,329 8/16/12 16:38 16,311 10/3/12 16:41 13,476
PRM 111.9 7/9/12 15:23 28,296 -- -- -- -- -- --
PRM 110.5 7/9/12 16:46 28,825 8/17/12 14:57 15,254 10/3/12 17:33 14,172
PRM 108.3 -- -- -- 8/17/12 17:55 16,394
PRM 107.1 7/9/12 18:26 28,409 8/18/12 13:12 15,508 10/4/12 14:10 14,558
PRM 106.1 -- -- -- 8/18/12 14:22 15,278 -- -- --
PRM 105.3 -- -- -- 8/18/12 15:52 15,362 -- -- --
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Project
River Mile
High Q Trip Mid Q Trip Low Q Trip
Date Time Discharge Date Time Discharge Date Time Discharge
PRM 104.7 -- -- -- 8/18/12 17:48 15,377 -- -- --
PRM 104.1 -- -- -- 8/19/12 12:49 15,345 -- -- --
PRM 103.5 -- -- -- -- -- -- 10/4/12 16:49 14,575
PRM 102.7 7/10/12 13:53 26,635 -- -- -- -- -- --
PRM 101.4 -- -- -- -- -- -- -- -- --
PRM 98.4 7/11/12 14:09 46,499 8/20/12 14:51 40,623 10/5/12 14:37 39,065
PRM 97.0 7/11/12 18:27 45,118 8/20/12 17:03 40,261 -- -- --
PRM 91.6 8/21/12 14:55 46,330 -- -- --
PRM 91.0 7/12/12 15:39 43,922 8/21/12 16:51 46,197 -- -- --
PRM 88.4 -- -- -- 8/22/12 15:01 41,697 -- -- --
PRM 87.1 7/12/12 18:00 42,550 -- -- -- -- -- --
PRM 86.3 7/13/12 13:13 41,895 -- -- -- -- -- --
PRM 85.4 -- -- -- 8/22/12 18:01 40,468 -- -- --
PRM 84.4 -- -- -- 8/23/12 15:16 36,988 -- -- --
PRM 83.0 7/13/12 16:09 41,975 -- -- -- -- -- --
PRM 82.3 -- -- -- 8/23/12 17:52 37,947 -- -- --
PRM 80.0 -- -- -- 8/24/12 15:07 36,580 -- -- --
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Table 3. Metrics used to compare the representation and proportionality of habitat types between focus areas and non-
focus areas within each geomorphic reach.
Level Habitat Type Comparison Metric Numerator Denominator
Macro-
Habitat
Main Channel Percent of main channel that
is single unsplit main channel
Length of main channel
habitat (HDR)
Total length of main
channel (thalweg, R2)
Split Main Channel Percent of main channel that
is in split main channel
Length of main channel
that is in split main
channel (R2 calculated)
Total length of main
channel (thalweg, R2)
Braided Main Channel Percent of main channel that
is in braided main channel
Length of main channel
that is in braided main
channel (R2 calculated)
Total length of main
channel (thalweg, R2)
Side Channel Side channel length per river
mile
Total length of side
channels (HDR)
Total length of main
channel (thalweg, R2)
Upland Slough Upland slough length per
river mile
Total length of upland
slough habitat (HDR)
Total length of main
channel (thalweg, R2)
Side Slough Side slough length per river
mile
Total length of side
channel habitat (HDR)
Total length of main
channel (thalweg, R2)
Backwater density of backwaters
(#/mile) # backwaters (HDR) Total length of main
channel (thalweg, R2)
Tributary density of tributaries (#/mile) # tributaries (HDR) Total length of main
channel (thalweg, R2)
Tributary Mouth density of tributary mouths
(#/mile)
# Tributary Mouths
(HDR)
Total length of main
channel (thalweg, R2)
Clear Water Plume density of plumes (#/mile) # plumes (HDR) Total length of main
channel (thalweg, R2)
Mesohabitat
Glide or Run Percent of main/side channel
habitat in glide/run
Total length of Glide or
Run (HDR)
Total Length of Main +
Side Channel Habitat
(HDR)
Riffle Percent of main/side channel
habitat in riffle
Total length of Riffle
(HDR)
Total Length of Main +
Side Channel Habitat
(HDR)
Beaver Complex Percent of slough habitat that
is beaver complex
Total length of Beaver
Complex Habitat (HDR)
Total length of slough
habitat (HDR)
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 22 January 31, 2013 Table 4. Main channel habitat classifications by geomorphic reach in the Middle Susitna River Main Channel Type MR-1 MR-2 MR-3 MR-4 MR-5 MR-6 MR-7 MR-8 % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) Main Channel 67.2% 10,702 68.5% 74,908 73.2% 16,935 98.3% 66,004 75.9% 24,114 27.5% 96,245 28.0% 41,756 24.3% 18,432 Split Main Channel 0.0% 0 7.5% 8,148 15.6% 3,600 0.0% 0 15.2% 4,835 18.0% 62,885 52.0% 77,407 5.9% 4,453 Multi-Split Main Channel 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.0% 0 7.5% 26,400 0.0% 0 32.3% 24,430 Side Channel 32.8% 5,235 16.1% 17,646 9.0% 2,090 1.0% 699 6.2% 1,954 45.9% 160,659 19.6% 29,178 37.5% 28,398 Tributary Mouth 0.0% 0 1.0% 1,113 0.6% 129 0.6% 426 1.0% 305 0.4% 1,545 0.2% 319 0.0% 0 Clear Water Plume 0.0% 0 6.8% 7,470 1.7% 383 0.0% 0 1.7% 549 0.6% 2,143 0.2% 240 0.0% 0 Grand Total 100% 15,937 100% 109,285 100% 23,137 100% 67,128 100% 31,758 100% 349,877 100% 148,900 100% 75,714
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 23 January 31, 2013 Table 5. Main Channel mesohabitat classifications in the Middle Susitna River. Main Channel Mesohabitat MR-1 MR-2 MR-3 MR-4 MR-5 MR-6 MR-7 MR-8 % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) Main Channel 67.2% 10,702 68.5% 74,908 73.2% 16,935 98.3% 66,004 75.9% 24,114 27.5% 96,245 28.0% 41,756 24.3% 18,432 Glide or Run 67.2% 10,702 65.8% 71,956 71.3% 16,495 30.2% 20,305 75.9% 24,114 25.9% 90,760 22.9% 34,058 24.3% 18,432 Pool 0.0% 0 0.0% 0 0.0% 0 0.7% 500 0.0% 0 0.0% 0 0.0% 0 0.0% 0 Rapid 0.0% 0 0.0% 0 0.0% 0 38.0% 25,519 0.0% 0 0.0% 0 0.0% 0 0.0% 0 Riffle 0.0% 0 2.7% 2,953 1.9% 440 29.3% 19,680 0.0% 0 1.6% 5,485 5.2% 7,698 0.0% 0 Split Main Channel 0.0% 0 7.5% 8,148 15.6% 3,600 0.0% 0 15.2% 4,835 18.0% 62,885 52.0% 77,407 5.9% 4,453 Glide or Run 0.0% 0 7.5% 8,148 15.6% 3,600 0.0% 0 15.2% 4,835 17.7% 61,922 42.1% 62,623 5.9% 4,453 Riffle 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.3% 963 9.9% 14,784 0.0% 0 Multi-Split Main Channel 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.0% 0 7.5% 26,400 0.0% 0 32.3% 24,430 Glide or Run 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.0% 0 7.1% 24,922 0.0% 0 31.7% 24,008 Riffle 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.3% 882 0.0% 0 0.6% 422 Unidentified 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.0% 0 0.2% 595 0.0% 0 0.0% 0 Side Channel 32.8% 5,235 16.1% 17,646 9.0% 2,090 1.0% 699 6.2% 1,954 45.9% 160,659 19.6% 29,178 37.5% 28,398 Glide or Run 32.8% 5,235 5.2% 5,716 7.2% 1,677 0.0% 0 4.2% 1,329 25.3% 88,662 13.1% 19,536 28.4% 21,528 Pool 0.0% 0 0.0% 0 0.0% 0 0.5% 342 0.0% 0 0.0% 0 0.0% 0 0.0% 0 Riffle 0.0% 0 0.0% 0 0.0% 0 0.5% 357 2.0% 625 0.7% 2,522 0.2% 279 9.1% 6,870 Unidentified 0.0% 0 10.9% 11,930 1.8% 414 0.0% 0 0.0% 0 19.9% 69,475 6.3% 9,363 0.0% 0 Tributary Mouth 0.0% 0 1.0% 1,113 0.6% 129 0.6% 426 1.0% 305 0.4% 1,545 0.2% 319 0.0% 0 Clear Water Plume 0.0% 0 6.8% 7,470 1.7% 383 0.0% 0 1.7% 549 0.6% 2,143 0.2% 240 0.0% 0 Total 100% 15,937 100% 109,285 100% 23,137 100% 67,128 100% 31,758 100% 349,877 100% 148,900 100% 75,714
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 24 January 31, 2013 Table 6. Off channel habitats classified in the Middle Susitna River. Off-Channel and Tributary Habitats MR-1 MR-2 MR-3 MR-4 MR-5 MR-6 MR-7 MR-8 % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) % Total (ft) Backwater 0.0% 0 0.0% 0 0.4% 91 0.0% 0 0.9% 1,236 1.5% 1,458 1.5% 453 0.3% 201 Side Slough 0.0% 0 4.5% 712 0.0% 0 66.8% 4,482 27.5% 38,898 10.0% 10,038 20.6% 6,195 20.2% 16,130 Beaver Complex 0.0% 0 0.0% 0 0.0% 0 0.0% 0 3.8% 5,393 2.6% 2,584 0.0% 0 0.0% 0 Side Slough 0.0% 0 4.5% 712 0.0% 0 66.8% 4,482 23.7% 33,505 7.4% 7,454 20.6% 6,195 20.2% 16,130 Tributary 0.0% 0 95.5% 14,946 99.6% 24,700 33.2% 2,232 41.7% 59,066 38.8% 38,945 24.1% 7,266 60.4% 48,143 Upland Slough 0.0% 0 0.0% 0 0.0% 0 0.0% 0 29.9% 42,361 49.8% 50,067 53.8% 16,190 19.1% 15,261 Beaver Complex 0.0% 0 0.0% 0 0.0% 0 0.0% 0 8.8% 12,512 5.0% 5,011 0.0% 0 0.0% 0 Upland Slough 0.0% 0 0.0% 0 0.0% 0 0.0% 0 21.1% 29,849 44.8% 45,056 53.8% 16,190 19.1% 15,261 Grand Total 0.0% 0 100% 79,735 100% 15,658 100% 24,791 100% 6,713 100% 141,561 100% 100,508 100% 30,104
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 25 January 31, 2013
Table 7. Counts of tributaries with potential fish habitat in the Middle River.
Inside FAs Outside of FAs Total
MR-2 2 8 10
MR-5 1 0 1
MR-6 3 19 22
MR-7 1 12 13
MR-8 1 0 1
Table 8. Estimated bias for each proportionality metric (total for reach – focus area) where estimates could be made.
Statistical comparison was made using a t-test or nonparametric alternative when the sample size (number of geomorphic
reaches with bias estimate) was greater than three.
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8
Average
Bias p-value
Main Channel -5.0% -9.5% -17% 42% -23% -2.3% 0.85
Split Main 5.0% 9.5% 22% -42% -3.7% -1.8% 0.87
Braided Main -5.5% 26% 10.4% n/a
Side Channel -0.021 -0.032 0.073 0.17 0.14 -0.13 0.033 0.52
Side Slough -0.33 0.17 -0.070 0.13 -0.14 -0.049 0.62
Upland Slough 0.035 0.035 -0.55 -0.024 -0.12 1
Backwaters 0.012 -1.3 -0.66 n/a
Tributaries 1.7 1.4 0.70 -0.86 0.72 0.29
Tributary Mouth 0.42 0.10 0.27 0.26 0.10
Clear Water Plumes 0.33 0.012 0.17 n/a
Beaver Complex -10% 13% 1.4% n/a
Glides/Runs -3.3% -2.0% 3.7% 13% 0.42% 2.4% 0.46
Riffles 3.3% 2.0% -3.7% -13% -0.42% -2.4% 0.46
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 26 January 31, 2013 Table 9. Habitat types by geomorphic reach and how representativeness will be achieved. (FA=Focus Area; CS=Cross-section). Habitat MR-1 MR-2 MR-5 MR-6 MR-7 MR-8 FA CS NEED FA CS NEED FA CS NEED FA CS NEED FA CS NEED FA CS NEED Main Channel X X X X X X Split Main Channel n/a X X X X X Braided Main Channel n/a n/a n/a X n/a X Side Channel X X X X X X Side Slough n/a X X X X X Upland Slough n/a X n/a X X X Beaver Complex n/a n/a n/a X X X Backwater n/a X n/a X X X Tributary n/a X X X X X Tributary Mouth n/a X X X X n/a Clear Water Plume n/a X X X X n/a
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 27 January 31, 2013
10. FIGURES
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 28 January 31, 2013 Figure 1. Map of the Middle Segment of the Susitna River depicting the eight Geomorphic Reaches and locations of proposed Focus Areas. No Focus Areas are proposed for in MR-3 and MR-4 due to safety issues related to sampling within or proximal to Devils Canyon.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 29 January 31, 2013 Figure 2. Map of the Lower Segment of the Susitna River depicting the six Geomorphic Reaches. Focus Areas have not been identified in this segment but will be considered pending results of open-water flow routing modeling.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 30 January 31, 2013 Figure 3. Map showing Focus Area 184 that begins at Project River Mile 184.7 and extends upstream to PRM 185.7. The Focus Area is located about 1.4 miles downstream of the proposed Watana Dam site near Tsusena Creek.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 31 January 31, 2013 Figure 4. Map showing Focus Area 173 beginning at Project River Mile 173.6 and extends upstream to PRM 175.4. This Focus Area is near Stephan Lake and consists of main channel and a side channel complex.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 32 January 31, 2013 Figure 5. Map showing Focus Area 171 beginning at Project River Mile 171.6 and extends upstream to PRM 173. This Focus Area is near Stephan Lake and consists of main channel and a single side channel with vegetated island.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 33 January 31, 2013 Figure 6. Map showing Focus Area 151 beginning at Project River Mile 151.8 and extends upstream to PRM 152.3. This single main channel Focus Area is at the Portage Creek confluence.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 34 January 31, 2013 Figure 7. Map showing Focus Area 144 beginning at Project River Mile 144.4 and extends upstream to PRM 145.7. This Focus Area is located about 2.3 miles upstream of Indian River and includes Side Channel 21 and Slough 21.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 35 January 31, 2013 Figure 8. Map showing Focus Area 141 beginning at Project River Mile 141.8 and extends upstream to PRM 143.4. This Focus Area includes the Indian River confluence and a range of main channel and off-channel habitats.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 36 January 31, 2013 Figure 9. Map showing Focus Area 138 beginning at Project River Mile 138.7 and extends upstream to PRM 140. This Focus Area is near Gold Creek and consists of a complex of side channel, side slough and upland slough habitats including Upper Side Channel 11 and Slough 11.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 37 January 31, 2013 Figure 10. Map showing Focus Area 128 beginning at Project River Mile 128.1 and extends upstream to PRM 129.7. This Focus Area consists of side channel, side slough and tributary confluence habitat features including Skull Creek.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 38 January 31, 2013 Figure 11. Map showing Focus Area 115 beginning at Project River Mile 115.3 and extends upstream to PRM 116.5. This Focus Area is located about 0.6 miles downstream of Lane Creek and consists of side channel and upland slough habitats including Slough 6A.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 39 January 31, 2013 Figure 12. Map showing Focus Area 104 beginning at Project River Mile 104.8 and extends upstream to PRM 106. This Focus Area covers the diverse range of habitats in the Whiskers Slough complex.
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 40 January 31, 2013
Figure 13. Percent of main channel in single main, split main, and braided main channel habitat by geomorphic reach
and focus area (F), non-focus area (NF), and total (T).
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
F NF T F NF T F NF T F NF T F NF T F NF T
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8% of Main Channel HabitatBraided Main Channel
Split Main Channel
Single Main Channel
DRAFT 2013 FOCUS AREA AND STUDY S ITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 41 January 31, 2013
Figure 14. Side channel, side slough, and upland slough lengths per mile of main channel by geomorphic reach and focus
area (F), non-focus area (NF), and total (T).
Figure 15. Percent of slough habitat that is in beaver complex by geomorphic reach and focus area (F), non-focus area
(NF), and total (T).
0
0.5
1
1.5
2
2.5
F NF T F NF T F NF T F NF T F NF T F NF T
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8Length in Side Habitats/Main Channel LengthUpland Slough/Main Channel
Side Slough/Main Channel
Side Channel/Main Channel
0%
5%
10%
15%
20%
25%
30%
35%
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8Percent of Slough Habitat in Beaver ComplexesFocus Areas
Non Focus Areas
Total
DRAFT 2013 FOCUS AREA AND STUDY SITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 42 January 31, 2013
Figure 16. Backwaters, tributaries, tributary mouths, and plumes by geomorphic reach and focus area (F), non-focus
area (NF), and total (T). Top graph is counts. Bottom graph is density (#/mile).
0
10
20
30
40
50
60
70
80
F NF T F NF T F NF T F NF T F NF T F NF T
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8Count Clear Water Plumes
Trib Mouths
Tributaries
Backwaters
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
F NF T F NF T F NF T F NF T F NF T F NF T
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8#/MileClear Water Plume Density
Trib Mouth Density
Tributary Density
Backwater Density
DRAFT 2013 FOCUS AREA AND STUDY S ITE SELECTION – TECHNICAL MEMORANDUM
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 43 January 31, 2013
Figure 17. Percent of main and side channel habitat that is in riffle vs. glide/run habitat by geomorphic reach and focus
area (F), non-focus area (NF), and total (T).
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
F NF T F NF T F NF T F NF T F NF T F NF T
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8Percent of Main + Side ChannelRiffle
Glide/Run