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Susitna-Watana Hydroelectric Project Document
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Title:
River productivity study, Study plan Section 9.8 : Initial study report
SuWa 207
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Prepared by R2 Resource Consultants, Inc., Alaska Cooperative Fish and Wildlife Research Unit,
University of Alaska Fairbanks
AEA-identified category, if specified:
Draft initial study report
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Series (ARLIS-assigned report number):
Susitna-Watana Hydroelectric Project document number 207
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Published by:
[Anchorage : Alaska Energy Authority, 2014]
Date published:
February 2014
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Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Study plan Section 9.8
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Draft
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230 p. in various pagings
(including all parts)
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Notes:
The following parts of Section 9.8 appear in separate files: Main report ; Appendices.
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
River Productivity Study
Study Plan Section 9.8
Initial Study Report
Prepared for
Alaska Energy Authority
Prepared by
R2 Resource Consultants, Inc.
Alaska Cooperative Fish and Wildlife Research Unit,
University of Alaska Fairbanks
February 2014 Draft
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i February 2014 Draft
TABLE OF CONTENTS
Executive Summary .......................................................................................................................x
1. Introduction ........................................................................................................................1
2. Study Objectives.................................................................................................................3
3. Study Area ..........................................................................................................................4
4. Methods and Variances In 2013 .......................................................................................4
4.1. River Productivity Implementation Plan ...........................................................5
4.2. Site Selection .....................................................................................................5
4.2.1. Middle River Stations / Focus Areas ...............................................6
4.2.2. Lower River Station .........................................................................6
4.2.3. Talkeetna River Station....................................................................7
4.2.4. Variances..........................................................................................7
4.3. Synthesize existing information on the impacts of hydropower
development and operations (including temperature and turbidity) on
benthic macroinvertebrate and algal communities ............................................8
4.3.1. Variances..........................................................................................9
4.4. Characterize the pre-Project benthic macroinvertebrate and algal
communities with regard to species composition and abundance in the
Middle and Lower Susitna River .......................................................................9
4.4.1. Benthic macroinvertebrate sampling ...............................................9
4.4.2. Benthic algae sampling ..................................................................11
4.4.3. Variances........................................................................................12
4.5. Estimate drift of invertebrates in selected habitats within the Middle
and Lower Susitna River to assess food availability to juvenile and
resident fishes...................................................................................................15
4.5.1. Variances........................................................................................16
4.6. Conduct a feasibility study in 2013 to evaluate the suitability of using
reference sites on the Talkeetna River to monitor long-term Project-
related change in benthic productivity .............................................................17
4.6.1. Variances........................................................................................17
4.7. Conduct a trophic analysis, using trophic modeling and stable isotope
analysis, to describe the food web relationships in the current riverine
community within the Middle and Lower Susitna River .................................18
4.7.1. Develop a trophic model to estimate how environmental
factors and food availability affect the growth rate potential
of focal fish species under current and future conditions ..............18
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii February 2014 Draft
4.7.2. Conduct stable isotope analysis of food web components to
help determine energy sources and pathways in the riverine
communities ...................................................................................19
4.7.3. Variances........................................................................................21
4.8. Generate habitat suitability criteria for Susitna benthic
macroinvertebrate and algal habitats to predict potential change in
these habitats downstream of the proposed dam site .......................................23
4.8.1. Variances........................................................................................23
4.9. Characterize the invertebrate compositions in the diets of
representative fish species in relationship to their source (benthic or
drift component)...............................................................................................23
4.9.1. Variances........................................................................................24
4.10. Characterize organic matter resources (e.g., available for
macroinvertebrate consumers) including coarse particulate organic
matter, fine particulate organic matter, and suspended organic matter
in the Middle and Lower Susitna River ...........................................................25
4.10.1. Variances........................................................................................26
4.11. Estimate benthic macroinvertebrate colonization rates in the Middle
Susitna River Segment under pre-Project baseline conditions to assist
in evaluating future post-Project changes to productivity in the Middle
Susitna River. ...................................................................................................26
4.11.1. Variances........................................................................................27
5. Results ...............................................................................................................................28
5.1. Synthesize existing literature on the impacts of hydropower
development and operations (including temperature and turbidity) on
benthic macroinvertebrate and algal communities. .........................................28
5.2. Characterize the pre-Project benthic macroinvertebrate and algal
communities with regard to species composition and abundance in the
Middle and Lower Susitna River. ....................................................................28
5.3. Estimate drift of benthic macroinvertebrates in selected habitats within
the Middle and Lower Susitna River to assess food availability to
juvenile and resident fishes. .............................................................................28
5.4. Conduct a feasibility study in 2013 to evaluate the suitability of using
reference sites on the Talkeetna River to monitor long-term Project-
related change in benthic productivity. ............................................................29
5.5. Conduct a trophic analysis to describe the food web relationships
within the current riverine community within the Middle and Lower
Susitna River. ...................................................................................................29
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii February 2014 Draft
5.6. Develop habitat suitability criteria for Susitna benthic
macroinvertebrate and algal habitats to predict potential change in
these habitats downstream of the proposed dam site. ......................................30
5.7. Characterize the invertebrate compositions in the diets of
representative fish species in relationship to their source (benthic or
drift component)...............................................................................................30
5.8. Characterize organic matter resources (e.g., available for
macroinvertebrate consumers) including coarse particulate organic
matter, fine particulate organic matter, and suspended organic matter
in the Middle and Lower Susitna River. ..........................................................30
5.9. Estimate benthic macroinvertebrate colonization rates in the Middle
Susitna Segment under pre-Project baseline conditions to assist in
evaluating future post-Project changes to productivity in the Middle
Susitna River. ...................................................................................................30
6. Discussion..........................................................................................................................30
7. Completing the Study ......................................................................................................33
8. Literature Cited ...............................................................................................................33
9. Tables ................................................................................................................................38
10. Figures ...............................................................................................................................55
APPENDICES
Appendix A: Review of the Effects of Hydropower on Factors Controlling Benthic Communities
Appendix B: Site-Specific Sample Collection Locations
Appendix C: Analysis of Potentially Dewatered River Productivity Sampling Sites in 2013
Appendix D: Talkeetna Site Selection Consultation Documentation
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv February 2014 Draft
LIST OF TABLES
Table 4.2-1. Locations and descriptions of Focus Areas selected as sampling stations for
the River Productivity study in the Lower and Middle River Segments of the Susitna
River. “X” indicates site established at that habitat type, “(x)” indicates no site
established at that habitat type. ..............................................................................................39
Table 4.4-1. Sampling Stations and Seasonal Sampling Event dates of collection for the
River Productivity study in the Lower and Middle River Segments of the Susitna
River, and the Talkeetna River. .............................................................................................40
Table 4.4-2. Benthic macroinvertebrate sample totals for 2013 sampling during three
index events (Spr= Spring, Sum=Summer, Fall) and Post-Storm sampling for sites in
the Middle and Lower River Segments of the Susitna River for the River
Productivity Study. ................................................................................................................41
Table 4.4-3. Adult emergence traps deployment locations with install and removal dates,
and count of number of collection visits with the number of successful samples
collected in2013. ....................................................................................................................42
Table 4.4-4. Composite algae sample totals for 2013 sampling during three index events
(Spr= Spring, Sum=Summer, Fall) and Post-Storm sampling for sites in the Middle
and Lower River Segments of the Susitna River, and Talkeetna (TKA) River for the
River Productivity Study. .......................................................................................................43
Table 4.5-1. Benthic drift and plankton tow sample totals for 2013 sampling during three
index events (Spr= Spring, Sum=Summer, Fall) and Post-Storm for sampling sites in
the Middle and Lower River Segments of the Susitna River, and Talkeetna (TKA)
River for the River Productivity Study. .................................................................................44
Table 4.6-1. Benthic macroinvertebrate sample totals for 2013 sampling during three
index events (Spr= Spring, Sum=Summer, Fall) for sites in the Talkeetna River
(TKA) for the River Productivity Study. ...............................................................................45
Table 4.6-2. Composite algae sample totals for 2013 sampling during three index events
(Spr= Spring, Sum=Summer, Fall) for sites in the Talkeetna (TKA) River for the
River Productivity Study. .......................................................................................................45
Table 4.6-3. Benthic drift and plankton tow sample totals for 2013 sampling during three
index events (Spr= Spring, Sum=Summer, Fall) for sites in the Talkeetna (TKA)
River for the River Productivity Study. .................................................................................45
Table 4.7-1. Itemized listing of sample components and the maximum potential number
of samples possible for collection for Stable Isotope Analysis from the four
sampling stations (16 sites total) in each study year in the Middle and Lower River
Segments of the Susitna River for the River Productivity Study, and the actual
number of samples collected and analyzed in 2013. ..............................................................46
Table 4.8-1. Number of Hess, algae, and snag samples collected with associated depth
(D), velocity (V), and substrate composition (Sub) measurements for 2013 sampling
during three index events (Spr= Spring, Sum=Summer, Fall) in the Middle and
Lower River Segments of the Susitna River for the River Productivity Study. ....................47
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v February 2014 Draft
Table 4.9-1. Itemized listing of the maximum potential number of fish gut content
samples possible for collection for the River Productivity Study in each study year,
and the number of actual samples collected and analyzed in 2013. ......................................48
Table 4.9-2. Number of fish collected for fish gut content, scales, and stable isotope
tissue samples during the Spring Index Event for each target species / age class from
each sampling site in the Middle and Lower River Segments of the Susitna River for
the River Productivity Study. .................................................................................................49
Table 4.9-3. Number of fish collected for fish gut content, scales, and stable isotope
tissue samples during the Summer Index Event for each target species / age class
from each sampling site in the Middle and Lower River Segments of the Susitna
River for the River Productivity Study. .................................................................................50
Table 4.9-4. Number of fish collected for fish gut content, scales, and stable isotope
tissue samples during the Fall Index Event for each target species / age class from
each sampling site in the Middle and Lower River Segments of the Susitna River for
the River Productivity Study. .................................................................................................51
Table 4.11-1. Colonization study sites in FA-104 (Whiskers Slough), with temperature
and turbidity conditions, and deployment and retrieval dates for Hester-Dendy
multiplate sampler sets for the five colonization time periods. .............................................52
Table 4.11-2. Number of Hester-Dendy multiplate samplers deployed at the four
colonization study sites in FA-104 (Whiskers Slough) for the five colonization time
periods. ...................................................................................................................................52
Table 4.11-3. Actual deployment duration for Hester-Dendy multiplate samplers at the
four colonization study sites in FA-104 (Whiskers Slough) for the five colonization
time periods. ...........................................................................................................................53
Table 5.2-1. Mean chlorophyll-a and Ash Free Dry Mass (AFDM) values (n=5) from
composite algae samples collected in 2013 during three index events for sites in the
Middle and Lower River Segments of the Susitna River, and Talkeetna (TKA) River
for the River Productivity Study. ...........................................................................................54
LIST OF FIGURES
Figure 3-1. Middle Susitna River Segment, with the four River Productivity sampling
stations /Instream Flow Focus Areas selected for the River Productivity Study, plus
the sampling station for reference sites on the Talkeetna River. ...........................................55
Figure 3-2. Lower Susitna River Segment, with Montana Creek area River Productivity
sampling station selected for the River Productivity Study. ..................................................56
Figure 4.2-1. Focus Area 184 (Watana Dam), and the three River Productivity sampling
sites. .......................................................................................................................................57
Figure 4.2-2. Focus Area 173 (Stephan Lake Complex), and the four River Productivity
sampling sites. ........................................................................................................................58
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vi February 2014 Draft
Figure 4.2-3. Focus Area 141 (Indian River), and the four River Productivity sampling
sites. .......................................................................................................................................59
Figure 4.2-4. Focus Area 104 (Whiskers Slough), and the five River Productivity
sampling sites. ........................................................................................................................60
Figure 4.2-5. Station RP-81 (Montana Creek), and the four River Productivity sampling
sites. .......................................................................................................................................61
Figure 4.2-6. Talkeetna Station (TKA), and the three River Productivity sampling sites. ...........62
Figure 4.4-1. Sampling equipment used to collect benthic macroinvertebrates in streams
and rivers. ...............................................................................................................................63
Figure 4.11-1. Hester-Dendy multiplate sampler set retrieved at RP-HD-3 on September
20, 2013. Declining flows over the previous week resulted in both large amounts of
sediment deposited at the site, which was then dewatered. ...................................................64
Figure 5.2-1. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals
from composite algae samples collected during three index events in 2013 for sites
within FA-184 (Watana Dam) in the Middle River Segment of the Susitna River. ..............65
Figure 5.2-2. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent
confidence intervals from composite algae samples collected during three index
events in 2013 for sites within FA-184 (Watana Dam) in the Middle River Segment
of the Susitna River. ...............................................................................................................65
Figure 5.2-3. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals
from composite algae samples collected during three index events in 2013 for sites
within FA-173 (Stephan Lake Complex) in the Middle River Segment of the Susitna
River. ......................................................................................................................................66
Figure 5.2-4. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent
confidence intervals from composite algae samples collected during three index
events in 2013 for sites within FA-173 (Stephan Lake Complex) in the Middle River
Segment of the Susitna River. ................................................................................................66
Figure 5.2-5. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals
from composite algae samples collected during three index events in 2013 for sites
within FA-141 (Indian River) in the Middle River Segment of the Susitna River. ...............67
Figure 5.2-6. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent
confidence intervals from composite algae samples collected during three index
events in 2013 for sites within FA-141 (Indian River) in the Middle River Segment
of the Susitna River. ...............................................................................................................67
Figure 5.2-7. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals
from composite algae samples collected during three index events in 2013 for sites
within FA-104 (Whiskers Slough) in the Middle River Segment of the Susitna
River. ......................................................................................................................................68
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vii February 2014 Draft
Figure 5.2-8. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent
confidence intervals from composite algae samples collected during three index
events in 2013 for sites within FA-104 (Whiskers Slough) in the Middle River
Segment of the Susitna River. ................................................................................................68
Figure 5.2-9. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals
from composite algae samples collected during three index events in 2013 for sites
within RP-81 (Montana Creek) in the Lower River Segment of the Susitna River...............69
Figure 5.2-10. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent
confidence intervals from composite algae samples collected during three index
events in 2013 for sites within RP-81 (Montana Creek) in the Lower River Segment
of the Susitna River. ...............................................................................................................69
Figure 5.2-11. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals
from composite algae samples collected during three index events in 2013 for sites
within the Talkeetna River study station................................................................................70
Figure 5.2-12. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent
confidence intervals from composite algae samples collected during three index
events in 2013 for sites within the Talkeetna River study station. ........................................70
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page viii February 2014 Draft
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
°C degrees Celsius
°F degrees Fahrenheit
µm micrometer
AEA Alaska Energy Authority
AFDM ash free dry mass
BMI benthic macroinvertebrates
CPOM coarse particulate organic matter
EMAP Environmental Monitoring and Assessment Program
EPA Environmental Protection Agency
FA Focus Areas
FBOM fine benthic organic matter
FERC Federal Energy Regulatory Commission
FPOM fine particulate organic matter
ft2 square feet
FWS Fish and Wildlife Service
g gram
GRP growth rate potential
HSC habitat suitability curve
HSI habitat suitability index
IP Implementation Plan
ISR Initial Study Report
LWD large woody debris
MDN marine-derived nutrients
mm millimeter(s)
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ix February 2014 Draft
Abbreviation Definition
NAWQA National Water-Quality Assessment
NMFS National Marine Fisheries Service
OHWM ordinary high water mark
OM organic matter
PIT-tag Passive Integrated Transponder tags used to individually identify animals and monitor their
movements.
PVC Polyvinyl chloride
QA/QC quality assurance/quality control
RP River Productivity
RSP Revised Study Plan
SIA stable isotope analysis
SPD Study Plan Determination
TKA Talkeetna River
TWG Technical Workgroup
UAF University of Alaska Fairbanks
USEPA United States Environmental Protection Agency
USGS United States Geological Survey
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page x February 2014 Draft
EXECUTIVE SUMMARY
River Productivity Study 9.8
Purpose The overarching goal of this study is to collect baseline data to assist in
evaluating the effects of Project-induced changes in flow and the interrelated
environmental factors (temperature, substrate, water quality) on the benthic
macroinvertebrate and algal communities in the Middle and Lower Susitna
River.
Status The 2013 sampling season was successfully conducted from June 19 through
October 3, 2013. Sample results for most study components are pending
completion of processing by the contracted taxonomic laboratory, and
analyses will be conducted in the next year of study. The literature review
on the impacts of hydropower development and operations on benthic
macroinvertebrate and algal communities is completed, and is included as an
appendix to this report.
Study
Components
Synthesize existing literature on the impacts of hydropower development and
operations (including temperature and turbidity) on benthic
macroinvertebrate and algal communities.
Characterize the pre-Project benthic macroinvertebrate and algal
communities with regard to species composition and abundance in the
Middle and Lower Susitna River.
Estimate drift of benthic macroinvertebrates in selected habitats within the
Middle and Lower Susitna River to assess food availability to juvenile and
resident fishes.
Conduct a feasibility study in 2013 to evaluate the suitability of using
reference sites on the Talkeetna River to monitor long-term Project-related
change in benthic productivity.
Conduct a trophic analysis to describe the food web relationships within the
current riverine community within the Middle and Lower Susitna River.
Develop habitat suitability criteria for Susitna benthic macroinvertebrate and
algal habitats to predict potential change in these habitats downstream of the
proposed dam.
Characterize the invertebrate composition in the diets of representative fish
species in relationship to their source (benthic or drift component).
Characterize organic matter resources (e.g., available for macroinvertebrate
consumers) including coarse particulate organic matter, fine particulate
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page xi February 2014 Draft
River Productivity Study 9.8
organic matter, and suspended organic matter in the Middle and Lower
Susitna River.
Estimate benthic macroinvertebrate colonization rates in the Middle Susitna
Segment under pre-Project baseline conditions to assist in evaluating future
post-Project changes to productivity in the Middle Susitna River.
2013 Variances AEA implemented the methods as described in the Study Plan with the
exception of the following variances. The significance of these variances is
discussed within the ISR.
Lower River site was moved from Trapper Creek to Montana Creek (IP
Section 2.1.3). See ISR Section 4.2.4.1.
Sampling at the FA-173 (Stephan Lake Complex) upland slough replaced by
small unnamed tributary mouth (FERC SPD, B-181). See ISR Section
4.2.4.2.
Storm event sampling at side slough at FA-173 (Stephan Lake Complex)
instead of FA-144 (Slough 21); upper and lower end sites not established
(RSP Section 9.8.4.3; IP Section 2.1.2). See ISR Sections 4.2.4.3. and
4.4.3.2.
Frequent and rapid river stage changes limited sampling sites available with
30-day periods of continuous inundation (RSP Section 9.8.4.3; IP Section
2.2.1). See ISR Section 4.4.3.1.
Number of depth and velocity measures intended to evaluate shoreline
bathymetry reduced for each Hess sample (RSP Section 9.8.4.3; IP Section
2.2.1). See ISR Section 4.4.3.1.
Algae samples were taken from stones and woody debris as opposed to fine
sediment in grab samples (FERC SPD, B-187). See ISR Section 4.4.3.3.
Plankton tows were conducted at 5 still water sites instead the potential total
of 11 recommended by FERC (FERC SPD, B-188). See ISR Section 4.5.1.1.
Dry weights for macroinvertebrate taxa will be estimated using length-
weight relationship data from UAF (RSP Section 9.8.4.3; IP Section 2.2.2.).
See ISR Section 4.4.3.4.
The Talkeetna reference station features a side channel, side slough, and
upland slough, and does not include a main channel macrohabitat type (IP
Section 2.1.4). See ISR Section 4.6.1.
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page xii February 2014 Draft
River Productivity Study 9.8
Stable isotope site selection was increased from the original two stations (3
sites each) to four stations, sampling 16 sites total (IP Section 2.11.1; FERC
SPD, B-201). See ISR Section 4.7.3.1.
Macrohabitat-specific subcutaneous dye marking was not used to track
movements of juvenile chinook, coho or rainbow trout less than 60 mm long
(FERC SPD, B-199). See ISR Section 4.7.3.2.
Fish stomach content samples were not assessed in the field as to whether the
stomach was empty or not (IP Section 2.8.1.). See ISR Section 4.9.1.1.
Dry weights for prey items in stomach contents will be estimated using
length-weight relationship data from UAF (IP Section 2.8.2.). See ISR
Section 4.9.1.2.
Hester-Dendy Samplers were not pre-conditioned before deployment (IP
Section 2.9.1). See ISR Section 4.11.1.
Steps to
Complete the
Study
[As explained in the cover letter to this draft ISR, AEA’s plan for completing
this study will be included in the final ISR filed with FERC on June 3, 2014.]
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page xiii February 2014 Draft
River Productivity Study 9.8
Highlighted
Results and
Achievements
Key achievements of the River Productivity Study are as follows.
1. Benthic samples collected during the three index events in 2013 were
comprised of 301 Hess samples, 155 LWD (snag) samples, 85 petite Ponar
grab samples, 45 adult emergence traps, and 105 Hester-Dendy samples.
These samples were successfully transported to the contracted taxonomic
laboratory in 2013, and results are pending upon completion of processing.
2. Benthic algae samples collected during the three index events in 2013
were comprised of 309 composite algae samples. Results were summarized,
and generally indicated that algae were lower in mainstem macrohabitats
than off-channel habitats (side sloughs, upland sloughs).
3. Drift samples collected during the three index events in 2013 were
comprised of 104 drift samples and 95 plankton tows. These samples were
successfully transported to the contracted taxonomic laboratory in 2013, and
are being processed.
4. The Talkeetna River was sampled for 30 Hess samples, 45 composite
algae samples, 15 petite Ponar grabs, 12 drift samples, and 10 plankton tows
during the three index events in 2013, to assess the feasibility of the
Talkeetna as a reference site for the Middle Susitna River. These samples
were successfully transported to the contracted taxonomic laboratory in
2013, and are being processed.
5. A total of 1,242 sample components were collected in 2013 for Stable
Isotope Analyses, which included collection of stomach contents from 261
Chinook salmon, coho salmon, and rainbow trout . These samples were
successfully transported to UAF laboratory in 2013 for ongoing analyses.
6. A total of 105 Hester-Dendy multiplate samplers were collected at 4 sites
reflecting different temperature/turbidity combinations over an 8-week
colonization period. These samples were successfully transported to the
contracted taxonomic laboratory in 2013, and are being processed.
INITIAL STUDY REPORT RIVER PRODUCTIVITY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 February 2014 Draft
1. INTRODUCTION
On December 14, 2012, Alaska Energy Authority (AEA) filed its Revised Study Plan (RSP) with
the Federal Energy Regulatory Commission (FERC or Commission) for the Susitna-Watana
Project, FERC Project No. 14241, which included 58 individual study plans (AEA 2012).
Included within the RSP was the River Productivity Study, Section 9.8. RSP Section 9.8 focuses
on collecting baseline data to assist in evaluating the effects of Project-induced changes in flow
and the interrelated environmental factors upon the benthic macroinvertebrate and algal
communities in the Middle and Upper Susitna River.
On February 1, 2013, FERC staff issued its study plan determination (February 1 SPD) for 44 of
the 58 studies, approving 31 studies as filed and 13 with modifications. FERC requested
additional information before issuing a SPD on the remaining studies. The Susitna River
Productivity Study Implementation Plan (RP IP) was presented and discussed during a Technical
Work Group (TWG) meeting on February 14, 2013. With consideration of the comment and
suggestions received from licensing participants, a RP IP was filed with FERC on March 1,
2013. On April 1, 2013 FERC issued its study determination (April 1 SPD) for the remaining 14
studies; approving 1 study as filed and 13 with modifications. RSP Section 9.8 was one of the 13
approved with modifications. In its April 1 SPD, FERC recommended the following:
Modified Sampling Locations
We recommend that AEA remove the proposed Upper River mainstem study stations
(RP -248 and RP-233).
Macrohabitat Replicates
We recommend that AEA sample in all unique macrohabitat types present at each
proposed study station for river productivity sampling in the Middle River and Lower
River segments. This would result in 16 sites in the Middle River and five sites in the
Lower River. AEA should collect samples in each macrohabitat type as feasible using
sampling methods and devices proposed in its RSP and final RP IP, with the
modifications we recommend below in Turbidity and Vegetation Influence, Benthic
Sampling Methods, Water Column and Surface Sampling, Organic Matter Sample
Processing, Benthic Macroinvertebrate Sampling on Snags, Emergence Sampling, and
Trophic Modeling.
Turbidity and Vegetation Influence
We recommend that AEA conduct macroinvertebrate drift sampling upstream and
immediately downstream of tributary mouths to collect information needed to assess
the relative contribution of tributaries and the mainstem Susitna River to fish food
resources.
Benthic Sampling Methods
We recommend AEA collect BMI and algae samples in macrohabitats with fine
substrate and low velocities using a bottom dredge or grab sampler. AEA should
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select the most appropriate sampler according to the bottom substrate, water velocity,
and other conditions (see Klemm et al. 1990), but should endeavor to use the same
sampler in all macrohabitats of this type to ensure consistency among samples.
Additionally, AEA should sample benthic algae on cobble substrates at multiple depths
up to 3 feet (e.g., depth categories of 0–1 foot, 1–2 feet, and 2–3 feet) at each
macrohabitat site (main channel, tributary confluences, side channels, and sloughs),
to the extent feasible given the limits of field safety.
Water Column and Surface Sampling
We recommend that AEA sample invertebrates in the water column and the water
surface of still water areas in one side slough, one upland slough, and one tributary
mouth (if present) at each study station in the Middle River and Lower River using a
modified plankton tow or similar sampler. Five replicates should be collected along a
single transect at each site.
Organic Matter Sample Processing
We recommend that AEA obtain AFDM measures of biomass from samples of benthic
and transported organic matter, using generally accepted scientific methods (section
5.9(b)(6)).
Benthic Macroinvertebrate Sampling on Snags
We recommend that AEA sample BMI on measured and representative portions of
LWD in situ by dislodging organisms by hand and collecting them in a net as they
enter the water column at each sample site.
For consistency, we also recommend that AEA use of the term “large woody debris”
(LWD) as defined here: “LWD must be at least 0.1 meter (4 inches) in diameter, and
at least 1.0 meter (39 inches) of the LWD must be below the water’s surface at
bankfull flow” and apply it consistently when referring to “wood” and “snags” in its
RSP and future study reports.
Emergence Sampling
We recommend that AEA sample aquatic insect emergence in ice free areas, if
available, beginning in April, then remove the traps during ice breakup and redeploy
them following ice breakup in late May or early June.
Trophic Modeling
For fish sampled for use in the growth and trophic modeling studies, we recommend
that AEA measure, weigh, and mark the first 50 fish of each target species and age
class captured within each sampled macrohabitat by PIT-tagging to identify the
capture station and date. We recommend that AEA collect fish for the trophic
modeling studies at all available macrohabitat types (up to five per study station) in
each Middle River and Lower River study station. Growth data collected from fish
marked and recaptured in the same macrohabitat site should be used (if possible) to
validate AEA’s proposed growth rate potential model. We also recommend that AEA
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incorporate flow velocity into its foraging models and account for associated capture
efficiencies when establishing consumption rate.
Stable Isotope Analysis
We recommend that AEA consult with NMFS and FWS when identifying the
appropriate two focus areas for stable isotope sampling, where within the focus areas
each type of stable isotope samples would be collected, and the number of adult
salmon tissue samples to be collected.
Talkeetna River Reference Study Station
We recommend that AEA consult with the TWG when selecting the Talkeetna River
reference study station.
In accordance with the April 1 SPD, AEA has adopted the FERC requested modifications.
Following the first study season, FERC’s regulations for the Integrated Licensing Process (ILP)
require AEA to “prepare and file with the Commission an initial study report describing its
overall progress in implementing the study plan and schedule and the data collected, including an
explanation of any variance from the study plan and schedule.” (18 CFR 5.15(c)(1)) This Initial
Study Report (ISR) on River Productivity has been prepared in accordance with FERC’s ILP
regulations and details AEA’s status in implementing the study, as set forth in the FERC-
approved RSP, RP IP, and as modified by FERC’s April 1 SPD (collectively referred to herein as
the “Study Plan”).
2. STUDY OBJECTIVES
The study objectives were established in the Study Plan (RSP Section 9.8.1). The overarching
goal of this study is to collect baseline data to assist in evaluating the effects of Project-induced
changes in flow and the interrelated environmental factors (temperature, substrate, water quality)
upon the benthic macroinvertebrate and algal communities in the Middle and Lower Susitna
River. Individual objectives that will accomplish this are listed below.
• Synthesize existing literature on the impacts of hydropower development and operations
(including temperature and turbidity) on benthic macroinvertebrate and algal
communities.
• Characterize the pre-Project benthic macroinvertebrate and algal communities with
regard to species composition and abundance in the Middle and Lower Susitna River.
• Estimate drift of benthic macroinvertebrates in selected habitats within the Middle and
Lower Susitna River to assess food availability to juvenile and resident fishes.
• Conduct a feasibility study in 2013 to evaluate the suitability of using reference sites on
the Talkeetna River to monitor long-term Project-related change in benthic productivity.
• Conduct a trophic analysis to describe the food web relationships within the current
riverine community within the Middle and Lower Susitna River.
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• Develop habitat suitability criteria for Susitna benthic macroinvertebrate and algal
habitats to predict potential change in these habitats downstream of the proposed dam
site.
• Characterize the invertebrate compositions in the diets of representative fish species in
relationship to their source (benthic or drift component).
• Characterize organic matter resources (e.g., available for macroinvertebrate consumers)
including coarse particulate organic matter, fine particulate organic matter, and
suspended organic matter in the Middle and Lower Susitna River.
• Estimate benthic macroinvertebrate colonization rates in the Middle Susitna Segment
under pre-Project baseline conditions to assist in evaluating future post-Project changes
to productivity in the Middle Susitna River.
3. STUDY AREA
As established by the Study Plan ( RSP Section 9.8.3), the River Productivity Study entails field
sampling throughout the Middle Segment and upper portion of the Lower Segment on the
Susitna River, as well as within the lower portion of the Talkeetna River (Figures 3-1 and 3-2).
The Middle Susitna River Segment encompasses the 85-mile section of river between the
proposed Watana Dam site and the Chulitna River confluence, located at PRM 102.4 (RM 98.6)
(Figure 3-1). Sampling activities within this segment are investigating the benthic communities
that may be affected by the Project and its regulated flows. Sampling has been conducted at
various distances from the proposed dam site to document longitudinal variability, and estimate
the effects that the proposed Project will have on benthos in the river system downstream. The
Lower Susitna River Segment, defined as the approximate 102-mile section of river between the
Three Rivers Confluence and Cook Inlet (Figure 3-2), has been sampled in this study to
document the current conditions within the upper portions of the segment, and estimate possible
Project operation effects, if any, that would affect benthic communities on the mainstem Susitna
River below the Three Rivers Confluence.
The Talkeetna River is an approximate 85-mile long tributary of the Susitna River, joining with
the Susitna and Chulitna rivers at the Three Rivers Confluence (Figure 3-1). Sampling activities
on the Talkeetna River are located approximately 8.5 – 9 miles upstream from the mouth, as an
effort to assess the feasibility of the Talkeetna River as a reference site for post-Project
monitoring activities.
4. METHODS AND VARIANCES IN 2013
This study employed a variety of field methods to build on the existing benthic
macroinvertebrate and algal community information in the Middle Susitna River. The following
sections provide brief descriptions of study site selection, sampling timing, the approach, and
methods that were used to accomplish each objective of this study.
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4.1. River Productivity Implementation Plan
This study report includes a description of the sampling scheme; however, the final sampling
scheme was reported in the River Productivity Implementation Plan, which was filed with FERC
on March 1, 2013 (R2 2013c).
The Implementation Plan included: (1) a summary of relevant macroinvertebrate and algal
studies in the Susitna River, (2) an overview of the life-histories of the target fish species in the
Susitna River that were selected for the trophic analysis, (3) a review of the preliminary results
of habitat characterization and mapping efforts (Characterization of Aquatic Habitat Study,
Study 9.9) and “Focus Areas” (FA) (Fish and Aquatic Instream Flow Study, Study 8.5), (4) a
description of site selection protocols, (5) a description of sampling protocols, (6) a description
of sample processing protocols, (7) a discussion of data analysis methods, (8) development of
field data collection forms, (9) development of database templates that comply with 2012 AEA
QA/QC procedures, and (10) FERC’s requested modifications included in the April 1 SPD. The
Implementation Plan included the level of detail sufficient to instruct field crews in data
collection efforts. In addition, the plan included protocol documents, specific sampling station
locations, details about the choice and use of sampling techniques and apparatuses, and a list of
field equipment needed. The Implementation Plan helped to ensure that field collection efforts
occurred in a consistent and repeatable fashion across field crews and river segments. Objective-
specific sampling methods are presented below.
4.2. Site Selection
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.2.4.).
Sampling was stratified by river segment and mainstem habitat type, as defined in the Project-
specific habitat classification scheme (e.g., main channel, tributary mouth, side channel, side
slough, and upland slough). Sampling occurred at five stations on the Susitna River, and one
station on the Talkeetna River, each station with three to five sites (establishing sites at all
macrohabitat types present within the station), for a total of 23 sites. In the Middle River
Segment, two stations were located between the dam site and the upper end of Devils Canyon,
and two stations were located between Devils Canyon and Talkeetna (Table 4.2-1; Figure 3-1).
All stations established within the Middle River Segment were located at Focus Areas
established by the Fish and Aquatic Instream Flow Study (R2 2013a; R2 2013b), in an attempt to
correlate macroinvertebrate data with additional environmental data (flow, substrates,
temperature, water quality, riparian habitat, etc.) collected by other studies (e.g., Baseline Water
Quality Study, Study 5.5), and for macroinvertebrate habitat suitability curve and habitat
suitability index (HSC/HSI) development. Many of these Focus Areas were also used for
collecting target fish species for trophic analysis (RSP Section 9.8.4.7).
To determine to what extent, if any, the Project operations may affect benthic communities, as
well as the influence that the two tributaries may have on those communities below the
confluence of the Three Rivers, one station was located in the upper portion of the Lower River
(Figure 3-2). Station and site locations are discussed below.
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4.2.1. Middle River Stations / Focus Areas
Within the Middle River, each one of the four sampling locations was located within a Focus
Area (Table 4.2-1; Figure 3-1 and Figures 4.2-1 through 4.2-4). Two stations between the
proposed dam site and Devils Canyon were established in FA-184 (Watana Dam) and FA-173
(Stephan Lake Complex). Between Devils Canyon and Talkeetna, two stations were established
in FA-141 (Indian River) and FA-104 (Whiskers Slough).
FA-184 (Watana Dam) is located approximately 1.4 miles downstream of the proposed dam site
and provides a mainstem site and a side channel site within its 1-mile extent (Figure 4.2-1; Table
4.2-1). In order to meet our objective of sampling sites at 3 or more habitats, it was necessary to
move outside of the FA-184 (Watana Dam) to include a site at the mouth of Tsusena Creek. FA-
173 (Stephan Lake Complex) is located approximately 11.7 miles downstream of the proposed
dam site and contains a complex of main channel and off-channel habitats within a wide
floodplain, thus represented the greatest channel complexity within its geomorphic reach (MR-2;
Figure 4.2-2). FA-173 (Stephan Lake Complex) provided a mainstem site, a side channel site, a
side slough site, and a small tributary mouth site within its 1.8-mile extent (Table 4.2-1).
Below Devils Canyon, FA-141 (Indian River) and FA-104 (Whiskers Slough) were selected due
to the diversity of main- and off-channel habitats that they contained, and documented fish use in
and nearby these Focus Areas. FA-141 (Indian River) includes the Indian River confluence,
which is a primary Middle Susitna River tributary with high levels of fish use. FA-141 (Indian
River) provided a mainstem site, a tributary mouth site, a side channel site, and an upland slough
site within its 1.6-mile extent (Figure 4.2-3; Table 4.2-1). Focus Area FA-104 (Whiskers
Slough) is located approximately 2.4 miles upstream of the confluence of the Chulitna and
Susitna rivers, making it the downstream-most station in the Middle River for the River
Productivity Study. This Focus Area contains the confluence of Whiskers Creek, side channels,
and side slough habitats that have been documented as supporting juvenile and adult fish use.
FA-104 (Whiskers Slough) provided a main channel site, a side-channel site, a side slough site,
an upland slough site, and a tributary mouth site within its 1.2-mile extent (Figure 4.2-4; Table
4.2-1).
Two side slough sites were also established for storm event sampling. After review of historic
data (ADF&G 1983c; Hale et al. 1984) regarding the mainstem discharge required to overtop
various sloughs in the Middle River, slough sites were established in FA-104 (Whiskers Slough)
and FA-173 (Stephan Lake Complex). Both side sloughs maintained at least some wetted habitat
during the summer months, and were sampled as part of a seasonal sampling event (Section 4.2)
just prior to the storm event occurrence in August 2013 making these sites ideal for the pre- and
post-storm evaluation.
4.2.2. Lower River Station
Within the Lower River, one study station, with four sampling sites was established in
conjunction with Fish Distribution and Abundance (Study 9.6) sampling activities on the Lower
Susitna River around the Montana Creek mouth area (Table 4.2-1, Figures 3-2 and 4.2-5). This
Lower River station (RP-81 [Montana Creek]) was located within a 1.2-mile reach beginning
approximately 21 miles downstream of the confluence with the Chulitna and Talkeetna rivers.
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This area was complex, with split channels, side channels, upland sloughs, and tributary mouths
(Figure 4.2-5). Four sites were established at Station RP-81 (Montana Creek) including: 1) a
mainstem site, 2) a side channel site, 3) an upland slough site, and 4) a tributary mouth site
(Table 4.2-1).
4.2.3. Talkeetna River Station
One task within the River Productivity Study was to assess the feasibility of the Talkeetna River
as a reference site for post-Project monitoring activities. Because the Talkeetna River is outside
of the Project area, results from 2012 study efforts and historic information from the 1980s were
limited. Review of the literature has revealed a single USGS study which reports on water
quality and benthic macroinvertebrate data collected from the Talkeetna River, approximately 5
miles upstream from its mouth near a USGS gaging station (Frenzel and Dorava 1999). The
USGS sampling reach was limited to the main channel, with benthic macroinvertebrate sampling
taken off a cobble point bar. Unfortunately, access to this site was not permitted, due to its
location within or adjacent to Cook Inlet Regional Working Group land. The selection of the
station on the Talkeetna River for the feasibility study was initially limited to a review of
topographic maps and available orthographic images. Candidate sites were then selected and
visited with a site reconnaissance trip, in consultation with the TWG, on July 17, 2013. Sites
with physical conditions similar to those of the Middle River Focus Areas were visited. The
Talkeetna station selected featured both main channel and off-channel habitat types to allow for
the establishment of a side channel site, a side slough site, and an upland slough site (Table
4.2-1, Figures 3-1 and 4.2-6).
4.2.4. Variances
4.2.4.1. Lower River Station
The Study Plan stated in IP Section 2.1.3 “Within the Lower River Segment of the Susitna River,
the River Productivity Study will establish one study station, with five sampling sites located in
conjunction with individual sites proposed by the Instream Flow Study and Fish Distribution and
Abundance sampling activities on the Lower Susitna River around the Trapper Creek area.”
During the study site selection process in May and June 2013, the Fish Distribution and
Abundance study determined that Trapper Creek was unsuitable for the installation and proper
functioning of a rotary screw trap. The screw trap, and its supporting crew activities, was
therefore relocated to Montana Creek. Because the River Productivity study collaborated with
the Fish Distribution and Abundance study (Study 9.6) for capturing target fish species and ages
for trophic modeling (Section 4.7.1), stable isotope analysis (Section 4.7.2), and fish dietary
analysis (Section 4.9), the Lower Segment study station was relocated to the area of the Lower
Susitna River around the mouth of Montana Creek (approximately PRM 81). Due to the habitat
composition within the Montana Creek study station, the potential number of sampling sites was
reduced from five to four (main channel, side channel, upland slough, and tributary mouth). No
side slough habitat was available for sampling. This site relocation has no effect on any of the
study objectives, as it establishes one study station within the Lower River Segment. This
variance will be incorporated into the River Productivity Study sampling efforts in the next year
of study, to allow for comparability with 2013 efforts.
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4.2.4.2. Middle River Stations / Focus Areas
As stated in the April 1 SPD (B-181), FERC recommended that AEA sample in all unique
macrohabitat types present at each proposed study station for river productivity sampling in the
Middle and Lower River. At Focus Area FA-173 (Stephan Lake Complex), one of the
macrohabitat types present included an upland slough habitat. Lack of permission to access
Cook Inlet Regional Working Group land prevented sampling at this site. However, habitat
characteristics in the side slough that the upland slough flows into were similar to the upland
slough site, and additional sampling for slow-water habitat was conducted as recommended in
the April 1 SPD (B-186, 187). As such, this variance had no effect on accomplishing the study
objectives. This variance will be incorporated into the River Productivity Study sampling efforts
in the next year of study, to allow for comparability with 2013 efforts.
4.2.4.3. Storm Event Site Relocation
The Study Plan stated in RSP Section 9.8.4.3, “Additional sampling will be conducted both
before and after storm events that meet or exceed a 1.5-year flood event at two side slough sites,
located in two separate Focus Areas in the Middle River Segment between Portage Creek and
Talkeetna (AEA 2012 Section 8.5.4.2.1.2).” Within the Study Plan (IP Section 2.1.2), side
sloughs in FA-104 (Whiskers Slough) and FA-144 (Slough 21) were selected, based on historic
data (ADF&G 1983c; Hale et al. 1984) that indicated that both side sloughs required similar
levels of mainstem discharge for overtopping (ca. 22,000 to 25,000 cfs), and maintained at least
some wetted habitat during the summer months.
Initial site reconnaissance visits to these two side sloughs revealed the FA-104 (Whiskers
Slough) slough offered suitable riffle habitat for sampling with a Hess sampler, whereas FA-144
slough was largely low velocity, silted pools influenced heavily by a series of beaver ponds. As
a result, the FA-144 slough was considered not suitable for Hess sampling. Further
reconnaissance for a second side slough site for storm event sampling was planned for the end of
the summer seasonal sampling event in August 2013, but the major summer storm event
occurred near the conclusion of that sampling trip (August 22). In order to capture before-after
data at two side sloughs for the storm event, the side slough within FA-173 (Stephan Lake
complex) was substituted for the FA-144 slough. The two side sloughs were sampled previous
to the storm event during the summer seasonal sampling event (FA-104 [Whiskers Slough] on
August 12, FA-173 [Stephan Lake Complex] on August 19), and were subsequently sampled on
August 30-31 to capture the pre- and post-storm conditions. These adjustments made it possible
to accomplish the required sampling for the purpose of evaluating the effects of the storm event
in 2013. By utilizing sampling sites already sampled for the three Index Periods, the study
benefits from the extra data collection by providing a second post-flood event sampling during
the Fall Index period, which may give further information on recovery times. This variance will
be incorporated into the River Productivity Study sampling efforts in the next year of study.
4.3. Synthesize existing information on the impacts of hydropower
development and operations (including temperature and
turbidity) on benthic macroinvertebrate and algal communities
AEA implemented the methods as described in the Study Plan with no variances.
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Several reviews have been written on the effects that modified flows have on the benthic
communities residing below dams (Ward 1976; Ward and Stanford 1979; Armitage 1984; Petts
1984; Cushman 1985; Saltveit et al. 1987; Brittain and Saltveit 1989). A majority of these
reviews indicate that temperature and flow regimes are often the most important factors affecting
benthic macroinvertebrates below dams. The type of dam and its mode of operation will have a
large influence over the type and magnitude of effects on the receiving stream below. General
information on the effects of hydropower on riverine habitats, especially glacially-fed river
systems, as well as Project-specific information, was reviewed and synthesized in a white paper
entitled Review of the Effects of Hydropower on Factors Controlling Benthic Communities.
This document is included in this report as Appendix A. The white paper provides a literature
review summarizing relevant literature on macroinvertebrate and algal community information in
Alaska, including 1980s Susitna River data; reviews and summarizes literature on general
influences of changes in flow, temperature, substrate, nutrients, organic matter, turbidity, light
penetration, and riparian habitat on benthic communities; and reviews and summarizes the
potential effects of dams and hydropower operations, including flushing flows and load-
following, on benthic communities and their habitats.
4.3.1. Variances
No variances from the methods described in the Study Plan (RSP Section 9.8.4.1.) occurred
during the 2013 study season.
4.4. Characterize the pre-Project benthic macroinvertebrate and
algal communities with regard to species composition and
abundance in the Middle and Lower Susitna River
4.4.1. Benthic macroinvertebrate sampling
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.4.3).
Three sampling events (also referred to as Index Events) were conducted from June through
October in 2013 to capture seasonal variation in community structure and productivity. The
timing of events was influenced by availability of open water for sampling. A late ice-breakup
occurred in 2013, resulting in late Spring sampling that started on June 19, 2013. Information on
the specific sampling timing within the three Index events is given in Table 4.4-1. Timing was
also coordinated with fish sampling events for coho, Chinook salmon, and rainbow trout (target
species for Objective 5, Section 4.7) and with Fish Distribution and Abundance sampling efforts
within the focus areas (ISR Study 9.6).
Benthic macroinvertebrate sampling was largely conducted in fast-water mesohabitats (typically
riffles/runs) within main channel (i.e., main channel, side channels, and tributary mouths) and
off-channel macrohabitat types (i.e., side sloughs and upland sloughs), when present (Appendix
B). Shoreline bathymetry was evaluated and noted at each site to evaluate the risk of sampling in
areas that were not fully colonized as higher flows submerged new shoreline substrates. This
localized information was used in conjunction with the USGS gages at Gold Creek and above
Tsusena Creek to assess for conditions indicating adequate inundation levels for sampling. Sites
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with extensive and gradually sloping cobble shorelines were generally chosen so that ample
underwater substrates accessible would be available in the event of a drop in surface water level.
Sampling was conducted using a modified Hess sampler (0.93 ft2-area) with a 243-micrometer
(µm) mesh net (Canton and Chadwick 1984; Klemm et al. 1990). Replicate samples (n=5) were
collected at each site to allow for statistical testing of results for short- and long-term monitoring
(see Appendix B for imagery of all sampling locations). A total of 271 Hess samples were
collected from 19 of the 20 study sites in 2013 (Table 4.4-2). Measurements of depth, mean
water column velocity, mean boundary layer velocity (near bed), and substrate composition were
taken concurrently with benthic macroinvertebrate sampling at the sample location for future use
in HSC/HSI development in the instream flow studies (Instream Flow Study, Study 8.5,
Objective 6, Section 4.8). Hourly water temperatures were recorded by submerged temperature
loggers deployed at all sampling sites. Temperature loggers were deployed during Index Event 1
and were retrieved during Index Event 3, usually in conjunction with emergence trap placements.
Some macrohabitats lacked adequate riffle/run mesohabitat (e.g., side sloughs and upland
sloughs), and instead featured deeper pools with fine substrates and low velocity. Use of a Hess
sampler in this type of slow-water habitat was not appropriate; therefore, a petite Ponar grab
sampler was used (Table 4.2-2). Similar to Hess sample collections, replicate Ponar samples
(n=5) were collected to allow for statistical testing of results for short- and long-term monitoring.
A total of 70 Ponar grab samples were collected from 6 of the 20 study sites in 2013 (Table
4.4-2).
To determine both the timing and the amount of adult insect emergence (Cushman 1983),
floating emergence traps were deployed at each site. The emergence trap design was a low-
profile trap with a floating base (Figure 4.4-1), with a collection bottle or tray with alcohol
preservation attached to the trap to collect adult specimens (Cadmus and Pomeranz unpublished).
The trap was anchored to rebar stakes driven into the stream bed, or tied off to securely attached
vegetation, by a length of rope. Ethanol (95 percent) with glycerol added was placed into the
trap collection bottle, and samples were collected from deployed traps approximately every 2
weeks by field crews, from the initial deployment following ice breakup until the last seasonal
sampling event (September-October). A total of 64 collection visits were made to retrieve and
reset traps over the course of the 2013 open-water season, collecting 45 samples total (Table
4.4-3). A loss of 19 samples was recorded, due to a number of disturbances, including bear
damage, boat traffic, and fluctuating flow conditions.
Due to the prevalence of large woody debris (LWD) in the Susitna River, woody snags, if
present at a sampling site, were sampled as a substrate stratum for benthic macroinvertebrates.
Sampling methods for LWD were semi-quantitative, based upon protocols established by the
USGS (Moulton et al. 2002). For the purposes of this study, woody snags were defined as LWD,
adopting the definition from the RSP Section 9.13.4.2.1: “LWD must be at least 0.1 m (4 inches)
in diameter, and at least 1.0 meter (39 inches) of the LWD must be below the water’s surface at
bankfull flow” (AEA 2012).
Suitable LWD had been submerged for an extended period of time so as to be clearly colonized.
Up to five smaller, removable LWD samples, if present at the site, were removed from the water
by using a saw and placed over a plastic bin or in a bucket, and all benthic macroinvertebrates
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were removed by handpicking, brushing, and rinsing. The removed LWD sections were allowed
to dry for a period of time so that any missed organisms crawled out of the crevices and were
collected. Removed sections sampled were measured for length and average diameter to
determine surface area sampled. Each section originated from a separate piece of LWD, and
therefore counted as a separate, replicate sample. In addition, up to five pieces of immobile
LWD, if present at the site, were sampled in situ by dislodging organisms by hand and collecting
them in a D-net positioned immediately downstream as they entered the water column. Pieces of
LWD were not prevalent at all sites, resulting in a total of 155 samples collected from 16 of the
20 sites in 2013 (Table 4.4-2). Pieces of wood were mostly located in off-channel
macrohabitats; main channel sites rarely provided suitable LWD.
Benthic macroinvertebrate replicate samples were stored in individual containers and
immediately preserved in the field with 95 percent ethanol (non-denatured). Samples were
shipped to and processed by Ecoanalysts, Inc. (Moscow, Idaho) using sample processing
protocols established by the USEPA for the Rapid Bioassessment Protocols (Barbour et al. 1999)
and modified for use in Alaska (Major and Barbour 2001).
In support of the bioenergetics modeling (Section 4.7.1), biomass estimates will be taken for
primary invertebrate taxa collected for benthic and emergence sampling. The biomass of each
invertebrate taxon will be estimated from length measurements and taxon-specific length-weight
regression relationships. The body lengths (from head to abdomen, excluding antennae, legs,
setae, and other appendages) of a representative subsample of each invertebrate taxon collected
from each site are measured under a dissecting microscope using digital microscopy software
(Leica Application Suite). Length measurements are then converted to dry mass using length-
weight regression relationships developed specifically for each taxon. Additional benthic
macroinvertebrates and organic matter samples were also collected for stable isotope analysis
(Objective 5, Section 4.7.2).
4.4.2. Benthic algae sampling
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.4.3). To allow for correlation between collection, benthic algae was
collected concurrently with benthic macroinvertebrate sampling at all five stations. In fast -water
habitats, rock surfaces were sampled, based on the methods utilized by the USGS for the
NAWQA program (Moulton et al. 2002), the USEPA for the Rapid Bioassessment Protocol
(Barbour et al. 1999), and the USEPA for the Environmental Monitoring and Assessment
Program (EMAP; Lazorchak et al. 2000; Peck et al 2006). For the purposes of this study, a PVC
pipe area delimiter (1.65 in. diameter) with a rubber collar at one end was adopted, as
recommended by the EPA methods (Barbour et al. 1999; Lazorchak et al. 2000; Peck et al.
2006).
For each algal sample associated with a Hess sample, five rock substrates were randomly
collected. Rock substrates were evenly collected at multiple depths in one-foot depth categories
(e.g., 0 – 1 foot, 1 – 2 feet, and 2 – 3 feet) to the extent feasible, given the limits of field safety.
At each location where a cobble or rock substrate was collected, measurements of depth, mean
water column velocity, mean boundary layer velocity, and area substrate composition were taken
for future use in HSC/HSI development in the instream flow studies (Instream Flow Study, ISR
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Study 8.5, RSP Section 8.5.4.5.1.2.3.). Light availability was measured at each sample location
with an underwater light sensor to measure the photosynthetically-active radiation (PAR)
available to the algal community. PAR readings were taken from just below the water surface to
the stream bottom at regular 10-cm intervals. A turbidity measurement, using a portable
turbidity meter, was also taken at the sampling site to determine water clarity at the time of
collections.
For each rock, the area delimiter was placed on its upper surface, and the enclosed area on the
substrate was scrubbed with a small brush to remove any algal growth. The removed algal
material from the enclosed area and brush were then rinsed into a darkened sample container.
The five discrete collections taken from five cobbles were combined to make a composited
sample, which was placed on ice inside a cooler and kept in the dark until the sample was
processed. Five composited samples (one for each Hess sample) were collected at each site, for
a total of 309 composited algae samples in 2013 (Table 4.4-4).
In macrohabitats with deeper pools, low velocities, and finer substrates, the USGS NAWQA
program protocols were followed for epilithic or epidendric sampling. As a result, rock
substrates or pieces of woody debris, when present within the site, were used to collect algal
samples with the area delimiter.
Procedures for processing algal samples were taken directly from the Quantitative Microalgae
processing procedures (Moulton et al. 2002). An algae filtration apparatus was used to draw
subsamples of the composite sample through a 1.85-inch diameter (47-mm) glass fiber filter.
Two subsamples were taken from each composite sample to determine chlorophyll-a and ash
free dry mass (AFDM) in the laboratory. The subsample filters were folded, wrapped in tinfoil,
labeled, and stored in a freezer at -4° F until shipped overnight on dry ice to the processing
laboratory in Kirkland, Washington. The remaining volume of the sample component was
preserved in 10-percent formalin, and archived for additional analyses, if needed. Benthic algae
samples were processed in a laboratory, using Standard Methods (Eaton et al. 1998; SM 10200H,
SM 2540G).
Results generated from the collections include estimates of AFDM and chlorophyll-a. Each
measure will have the mean and variability (95-percent confidence intervals) calculated for each
site and index event.
4.4.3. Variances
4.4.3.1. Sampling site inundation requirements
The Study Plan stated that: “Higher flows may inundate new shoreline substrates, which poses
the risk of sampling in areas that are not fully colonized. The shoreline bathymetry for each site
will be evaluated such that changes in water level due to increasing or decreasing flows must
remain constant enough that the substrates accessible for sampling will be continually inundated
for a period of at least one month, to facilitate colonization of those substrates” (RSP Section
9.8.4.3.; IP Section 2.2.1.). While the preferred and intended practice was to conduct sampling
at sites where all substrates had remained submerged for 30 days or more, such a condition was
difficult to satisfy given the rapid and sudden changes in flow and river stage during the
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sampling season. Compliance with a 30-day inundation requirement would have prevented any
spring sampling from occurring, due to the delayed ice-break up period, followed by record-high
temperatures that increased glacial flows throughout the months of June and July. Summer
sampling would have been postponed for another 30 days due to a drop in flows and river stage
for a two-day period (August 8-9) a few days before the summer sampling period began (August
12). Instead, USGS gage data was reviewed daily and during periods of risk, sampling was
conducted at the maximum water depths allowed by the Hess sampler (12 to 14 inches), when
present and available, to pursue the highest probability of continuous inundation conditions. An
examination of Hess sampling depths and the recorded USGS river stage gage data was
conducted to estimate the potential exposures of Hess samples within the 30-days prior to sample
collection (Appendix C). Estimates revealed that 24-percent of the Hess samples, specifically
those in main channel macrohabitats, could have been potentially dewatered at some point during
the preceding 30 days due to river stage changes (Appendix C).
The Study Plan also indicated that “the shoreline bathymetry for each site will be evaluated” at
each site (RSP Section 9.8.4.3.; IP Section 2.2.1.). The Study Plan provided details that basic
surveying transects would be used at each Hess sampling location, measuring depth and velocity
at 3-foot intervals, both perpendicular and parallel to the shoreline. Initial transect measurement
efforts during the spring sampling event resulted in over 100 measurements of depth and velocity
at each site. A majority of the measurements had no direct relation to the samples collected, and
were therefore of little use for the trophic model (Section 4.7) and HSC/HSI curve development
(Section 4.8). At many sites, an established point at the ordinary high water mark (OHWM) was
not possible, making it difficult to establish a point of reference for the shoreline position,
especially when flows and river stages were prone to rapid changes. A formal surveying effort
would be needed to provide a set of measurements to survey the shoreline bathymetry. From a
logistics standpoint, the large number of transect measurements required a considerable amount
of time at each site, resulting in the completion of only one sampling site per day. Given that the
projected rate of progress needed to approach two completed sites per day in order to complete
all sampling sites within a 10 to 14 day period, transect measurements for a site’s shoreline
bathymetry were reduced to taking measurements at each sample location. General notes on site
features were recorded, and USGS gage data was reviewed before and during field sampling
efforts. By reducing measurements to just sample locations within each site, all sampling efforts
were able to be completed within a 14-day period, allowing for better comparability among sites
sampled within each seasonal event, and sample-specific depth and velocity measurements were
able to be made to satisfy the requirements for both the trophic modeling effort (Section 4.7), and
the HSC/HSI development effort (Section 4.8). This variance will be incorporated into the River
Productivity Study sampling efforts in the next year of study, to allow for comparability with
2013 efforts.
4.4.3.2. Storm event sampling
The Study Plan stated in RSP Section 9.8.4.3, “Additional sampling will be conducted both
before and after storm events that meet or exceed a 1.5-year flood event at two side slough sites,
located in two separate Focus Areas in the Middle River Segment between Portage Creek and
Talkeetna (RSP AEA 2012, Section 8.5.4.2.1.2).” Because of the timing of the late August storm
event, pre-storm sampling was not able to collect samples at both the upstream and downstream
ends of each slough, as stated in the Study Plan (RSP Section 9.8.4.3). Storm event sampling
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was limited to the summer sampling event and a repeated sample at two side slough sites located
in the middle of the slough (Tables 4.4-2, 4.4-4, and 4.5-1). By utilizing sampling sites already
sampled for the larger sampling efforts during the three Index Periods, repeating those sampling
efforts allowed for a complete before-after data collection for comparison. The study further
benefited by using the fall sampling event as a second post-flood collection, providing additional
information on recovery times from sudden flow increases. These adjustments made it possible
to accomplish the required sampling for the purpose of evaluating the effects of the storm event
in 2013. This variance will be incorporated into the River Productivity Study sampling efforts in
the next year of study, to allow for comparability with 2013 efforts.
4.4.3.3. Grab sampling in slow water areas
As stated in the Study Plan (April 1 SPD, B-187), it was recommended that AEA collect both
BMI and algae samples in macrohabitats with fine substrate and low velocities using a bottom
dredge or grab sampler. While the grab sampler is ideal for collecting macroinvertebrates in fine
sediment, it is unsuitable for sampling algae because the sediment surface is disturbed in the
process of collection and removal of the material from the grab sampler. The USGS National
Water-Quality Assessment (NAWQA) Program protocol, which was the model for this study’s
co-located algal and macroinvertebrate samples, recommends algal sample collections from
epilithic (natural, coarse-grained substrates) or epidendric (woody debris) habitats (Moulton et
al. 2002; Hambrook Berkman and Canova 2007). The USGS NAWQA protocol for algal
sampling from soft substrates uses the inverted petri dish method, but those samples are only
analyzed for taxonomic identification, and not chlorophyll-a or ash free dry mass (AFDM), as is
required for this study. Following the NAWQA protocols, this study therefore collected algae
samples for chlorophyll-a and AFDM from epilithic and epidendric substrates, when present, in
macrohabitats with fine substrate and low velocities, and collected benthic macroinvertebrates
and organic matter with the Petite Ponar grab. With the use of these protocols, algae collections
were possible in slow-water habitats, and samples were consistently collected as required for the
study objective (Section 4.4.2). The adoption of this protocol as a standard approach allowed for
study team to achieve the study objective. This variance will be incorporated into the River
Productivity Study sampling efforts in the next year of study, to allow for comparability with
2013 efforts.
4.4.3.4. Dry mass and energy density measurements
The methods of determining the biomass and energy density of benthic macroinvertebrates were
changed from the methods described in the Study Plan to improve accuracy and better achieve
the study objectives. The Study Plan (RSP Section 9.8.4.3; IP Section 2.2.2) stated that the
oven-dried biomass of benthic macroinvertebrates would be measured directly. Instead, the body
lengths of a subsample of each macroinvertebrate taxon were measured to the nearest millimeter.
The dry mass of each taxon was calculated from length-weight regression relationships derived
from the literature (e.g., Rogers et al. 1976, 1977; Smock 1980; Benke et al. 1999; Johnston and
Cunjak 1999; Sabo et al. 2002) and from recent studies of Alaskan stream invertebrates (M.
Wipfli, UAF, unpublished data). This approach is more accurate than direct measurements of
biomass from samples preserved in ethanol (Meyer 1989). This change also standardized the
estimation of invertebrate biomass between specimens collected from the environment (i.e.,
benthic and drift samples) and those collected from fish stomachs.
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The method of determining the energy density of invertebrates was also changed to improve
accuracy. The Study Plan (RSP Section 9.8.4.3) stated that energy density (J/g wet weight)
would be determined for a subsample of the benthic macroinvertebrate specimens from the
percent dry mass (dry mass/wet mass) of each sample (Ciancio et al. 2007; James et al. 2012).
This method would have produced accurate measurements if fresh invertebrate samples could
have been transported to the lab; however, this method was not suitable for samples preserved in
ethanol, which can cause substantial bias in dry mass measurements (Leuven et al. 1985).
Ethanol preservation was necessary for samples collected at many of the study sites due to the
duration of the sampling trips and the remote locations of the sites. Therefore, taxon-specific
energy density values were derived from the literature. These adjustments therefore increased
accuracy, reduced sampling bias, and provided a standard methodology for estimating biomass
and energy density while achieving the study objective. This variance will be incorporated into
the River Productivity Study sampling efforts in the next year of study, to allow for
comparability with 2013 efforts.
4.5. Estimate drift of invertebrates in selected habitats within the
Middle and Lower Susitna River to assess food availability to
juvenile and resident fishes
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.5.1).
Invertebrate drift sampling was conducted concurrently with benthic macroinvertebrate sampling
at all sites within the five established sampling stations to allow for comparisons between the
drift component and the benthic macroinvertebrate community, as well as reveal the availability
of terrestrial invertebrates for fish predation.
Sampling was conducted in fast-water habitats, if present, within all established sites (Tables
4.2-1 and 4.5-1). In addition, at all tributary mouth sites, a drift net pair was deployed upstream
of the site, to collect information on the relative contribution of tributaries to fish prey resources
in the mainstem Susitna River.
Invertebrate drift sampling was conducted based on the USEPA’s EMAP drift net sampling
protocols (Klemm et al. 2000). A set of two drift nets with a 250-µm mesh size were used to
collect duplicate samples to allow for statistical testing of results for short- and long-term
monitoring (Klemm et al 1990; Klemm et al. 2000). Drift sampling was conducted at the top of
a site reach during daylight hours, preferably beginning shortly after arrival at a site. Water
velocity was recorded with an in-net flow meter (General Oceanics) along with the start and stop
times marking the amount of time the nets were actively sampling. In addition, current velocity
was measured with a Pygmy current meter at the entrance of the net and at 60 percent of the
depth at the start and ends of sampling. Measurements of depth, turbidity, and temperature were
also taken with drift samples. A total of 92 drift samples were taken during the 2013 field season
(Table 4.5-1).
The use of drift nets is not advised with currents less than 0.16 feet per second (0.05 meters per
second); a plankton tow net (243-µm mesh net with a 8-inch opening) was used at still water
sites, taking five replicate horizontal tows along transects across the channel. Two calibrated
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tow lines were attached to the tow net, one going to a crew member on each side of the channel.
This arrangement allowed the collection of tows along shore-to-shore transects across the
channel without repetitive crossing, or attempts to toss the net to the other side of the channel.
Transect distance measurements were made upon retrieval of each tow. A total of 85 plankton
tows were collected from 8 of the 20 sites (Table 4.5-1).
Invertebrate drift and plankton tow samples were shipped to and processed by Ecoanalysts, Inc.
(Moscow, Idaho) using methods similar to those used for benthic samples (Barbour et al. 1999;
Major and Barbour 2001). Organic matter (OM) content was retained and analyzed by size
(coarse and fine particulate OM) as discussed in Section 4.10.
4.5.1. Variances
4.5.1.1. Plankton tow sampling in still water areas
As stated in the Study Plan (April 1 SPD, B-188), it was recommended that “AEA sample
invertebrates in the water column and the water surface of still water areas in one side slough,
one upland slough, and one tributary mouth (if present) at each study station in the Middle River
and Lower River using a modified plankton tow or similar sampler.” This effort would result in
a potential of eleven sites identified in the Implementation Plan where plankton tows could be
collected. However, the relocation of the Lower River Segment study station, and the lack of
permission to access the upland slough site in FA-173 (Stephan Lake Complex), reduced the
potential site number. In addition, most tributary mouth habitats did not present still water areas
in which to take plankton net tows. Most River Productivity sites were established in riffle/run
habitats, with measurable velocity. Upland sloughs were the exception, as they featured deeper
pools with little to no stream velocities. During summer and fall low-flow conditions, side
slough habitat also provided still water habitat areas for plankton tows. Therefore, as a general
rule, in cases where stream velocities were not high enough to take drift net samples, plankton
tows were used as a substitute. Plankton tows and grab samples were often taken together at
sites with low velocity. By defining the use of plankton tows to those flow conditions where
drift net sampling is not conducive (currents less than 0.16 feet per second), sampling of
organisms in the water column was possible at all sites, regardless of current velocities. This
adjustment provided a standardized approach for sampling the water column for invertebrates,
depending upon the velocity, and allowed the study team to achieve the study objective. This
variance will be incorporated into the River Productivity Study sampling efforts in the next year
of study, to allow for comparability with 2013 efforts.
4.5.1.2. Dry mass and energy density measurements
The methods for determining the biomass and energy density of macroinvertebrates were
changed as previously described above in Section 4.4.3.4.
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4.6. Conduct a feasibility study in 2013 to evaluate the suitability of
using reference sites on the Talkeetna River to monitor long-
term Project-related change in benthic productivity
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.6.1). In consultation with the TWG on July 16, 2013 (see Appendix
D for documentation material), three sampling sites were established in the Talkeetna River in
areas that were considered physically similar to those sampled in the Middle Susitna River
(Figure 3-1). These site selections were presented to the TWG on September 23, 2013. One
station was established with a mainstem site (side channel) and two off-channel habitat sites
(side slough and upland slough) within it (Table 4.2-1). Sampling was conducted in riffle
habitats in the side channel and side slough sites, and in low-velocity pools in the upland slough
site (Figure 4.2-6; Appendix B).
Benthic and drift sample timing was consistent with Index Events in the Middle River
(Objectives 2 and 3, Sections 4.4 and 4.5) (Table 4.4-1). Benthic macroinvertebrate, benthic
algae, and drift sampling methods and processing protocols were identical to those used in
sampling the Middle Susitna River (Objectives 2 and 3, Sections 4.4 and 4.5). A total of 30 Hess
samples, 15 Ponar grab samples, 45 composite algae samples, 12 drift samples, and 10 plankton
tows were collected in 2013 (Tables 4.6-1 to 4.6-3).
4.6.1. Variances
The Study Plan stated in IP Section 2.1.4.: “The Talkeetna station will feature both main channel
and off-channel habitat types to allow for the establishment of a main channel site, a side
channel site, and a side slough site.” However, as stated in the April 1 SPD (B-201), it was
recommended that AEA consult with the TWG when selecting the Talkeetna River reference
study station and sites. Candidate sites were selected, and visited with a site reconnaissance trip,
in consultation with the TWG, on July 16, 2013 (Appendix D). From that trip, a side channel,
side slough, and upland slough were selected as sampling sites. Although no main channel site
was established, the TWG representative agreed that a side channel was appropriate as a main
channel habitat within that braided reach of the Talkeetna River where the study station was
located. Given that the main channel habitat in the station location is primarily split main
channel and multiple split main channel, the selection of a side channel would serve a better
comparison with a Middle Susitna side channel. The inclusion of the upland slough as a
sampling site adds in a second off-channel habitat type to compare to the Middle Segment sites,
and therefore further assists in accomplishing the study objective of evaluating the Talkeetna
River as a future reference site for evaluating Project effects within a monitoring program. This
variance will be incorporated into the potential River Productivity Study sampling efforts in the
next year of study, should 2013 results indicate that further sampling in the Talkeetna River is
warranted.
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4.7. Conduct a trophic analysis, using trophic modeling and stable
isotope analysis, to describe the food web relationships in the
current riverine community within the Middle and Lower
Susitna River
4.7.1. Develop a trophic model to estimate how environmental factors and food
availability affect the growth rate potential of focal fish species under
current and future conditions
AEA implemented the methods as described in the Study Plan with no variances. To determine
how water temperature, food availability, and food quality influence the growth of juvenile
Chinook salmon, juvenile coho salmon, and juvenile and adult rainbow trout, field data from the
Fish and Aquatics Instream Flow Study (Study 8.5), Study of Fish Distribution and Abundance
in the Middle and Lower Susitna River (Study 9.6), and this River Productivity Study will be
analyzed using a bioenergetics approach. This analysis will allow comparisons of observed
growth rates, estimated consumption rates, and estimated growth efficiency (i.e., the grams of
growth achieved per gram of food consumed) among different habitats under the environmental
conditions observed during 2013 and the next year of study.
In 2013, growth rates were determined from seasonal mean weight at age data (IP Section 2.7.3)
by collecting fish scales in order to age juvenile Chinook salmon, juvenile coho salmon, and
juvenile and adult rainbow trout (DeVries and Frie 1996). Scales were collected from the first
eight fish of each species and age group captured at each sampling site, in conjunction with
stomach content sampling (Section 4.9) conducted with the assistance of the Fish Distribution
and Abundance Study (ISR Study 9.6). For field sampling purposes during 2013, rainbow trout
with length less than or equal to 120 mm (4.7 in) were provisionally categorized as “juveniles”
(ages 0 and 1) or as “adults” (ages 2 and above) if their fork length was greater than 120 mm (4.7
in) (ADF&G 1983b, pp. G-8, G-14; Sundet and Wenger 1984, part 5, pp. 69, 70).
Approximately six scales were collected using forceps from the preferred sampling area on the
fish (Scarnecchia 1979). Scales were stored dry in small paper envelopes and transported to the
laboratory for analysis.
Fish ages were determined using scales and temporal length distribution data (DeVries and Frie
1996; Isely and Grabowski 2007). Seasonal length-frequency distributions were examined for
juvenile Chinook salmon, juvenile coho salmon, and juvenile rainbow trout. If any species
displayed distinct length modes, suggesting that age-0 and age-1 fish were distinguishable from
each other and from older fish based on length and sampling date alone (e.g., Daum and
Flannery 2011), this method was validated by aging scales from a random subset of 80 fish per
size group. If seasonal length distributions did not contain distinct modes or if the length-
frequency analysis failed to correctly assign at least 95 percent of the fish to the correct age
based on the scale analysis, then all scales from that species were aged. Age classes of rainbow
trout aged 2 years and older were expected to overlap in length, so all rainbow trout were aged
by scale analysis only.
Scales of juvenile fish were removed from envelopes in the lab, soaked in water in a petri dish,
and cleaned of any slime and foreign material. One suitable scale (neither regenerated nor
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damaged) from each fish was examined under a dissecting microscope. Scales were aged
independently by two readers, with the final age assigned by consensus. Images of a subset of
scales were captured and archived with a microscope-mounted digital camera interfaced with a
desktop computer.
Growth rates of juvenile Chinook salmon, juvenile coho salmon, and rainbow trout were
quantified in terms of mean weight at age based on field data from all specimens sampled,
stratified by sampling period and station. To test whether size-selective mortality or migration
introduced bias into these growth rate estimates, seasonal growth rates were also estimated for
individual fish that were recaptured during the PIT tag study. The adopted growth relationships
were used as inputs for the bioenergetics models for each species.
Water temperatures were obtained from temperature loggers deployed at sampling stations
(Section 4.4). Diet composition was determined from stomach contents (Section 4.9). The
energy densities of prey taxa were derived from the literature. Based on these inputs, the
bioenergetics models estimated consumption rates and growth efficiency on a daily basis. These
metrics were compared among habitats and seasons to determine whether growth was limited
primarily by water temperature, food consumption, or food quality in the study area, and whether
these limiting factors differed among habitats (McCarthy et al. 2009).
4.7.2. Conduct stable isotope analysis of food web components to help
determine energy sources and pathways in the riverine communities
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.7.3). To better understand the trophic relationships in the Middle
and Lower Susitna River, stable isotope sampling was conducted at four stations; one in the
Lower River (RP-81 [Montana Creek]) and three in the Middle River (FA-104 [Whiskers
Slough], FA-141 [Indian River], and FA-184 [Watana Dam]) (Table 4.2-1 and Figures 3-1 and
3-2). A total of 1,242 tissue samples were collected for stable isotope analysis (SIA) from
multiple study components, including benthic macroinvertebrates, benthic algae, benthic organic
matter, invertebrates and organic matter in drift samples, salmon carcasses, and fin clips from
fish (Table 4.7-1). Samples were collected at all sites within these four stations, for a total of 16
sites, in conjunction with other related sampling efforts undertaken at each site/habitat type
(Sections 4.4, 4.5, 4.9, and 4.10).
For collection of stable isotope tissues from benthic macroinvertebrates and benthic organic
matter (BOM), qualitative sampling was conducted using either a modified Hess sampler or a
250-μm D-frame kick net. Three composite samples were collected from each site, yielding a
targeted wet weight of approximately 10 g (0.35 oz) BOM, and 2 to5 g (0.07 to 0.17 oz) for each
of four functional feeding groups of benthic macroinvertebrates. Separation of
macroinvertebrates from organic matter, identification, and sorting into feeding groups was
conducted using a dissecting microscope in the lab at the University of Alaska-Fairbanks (UAF).
Macroinvertebrates were sorted into functional feeding groups that each comprised a single
composited sample to be used for stable isotope analysis (Table 4.7-1). A total of 489 benthic
macroinvertebrate sample components and 141 benthic organic matter sample components were
collected for analysis in 2013.
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Benthic algae samples used for stable isotope analysis were collected in addition to the
quantitative algae samples collected for ash free dry mass (AFDM) and chl-a analysis (Section
4.4.2). Three composite samples representative of the periphyton assemblage present in each
habitat type were collected at each site, targeting a wet weight of 10 g (0.35 oz). Each composite
sample was collected by thoroughly brushing the top and side surfaces of five haphazardly
selected rocks and retaining the loosened algal material for analysis in the lab at UAF. A total of
141 benthic algae sample components were collected for analysis in 2013 (Table 4.7-1).
For collection of stable isotope material from drifting invertebrates and organic matter (seston),
qualitative sampling was conducted using a pair of drift nets with 250-μm mesh. Two composite
samples were collected from each site where drift sampling could be conducted, yielding a
targeted wet weight of approximately 10 g (0.35 oz) seston, and 2 to 5 g (0.07 to 0.17 oz) for
each composite sample of benthic macroinvertebrates. A total of 102 drift sample components
and 94 seston sample components were collected for analysis in 2013 (Table 4.7-1). All samples
were preserved in 70 percent ethanol and returned to UAF for further analysis.
For collection of stable isotopes from emerging adult aquatic insects, sample material was taken
from emergence trap samples collected as described in Section 4.4.1. Samples were sent to
Ecoanalysts, Inc. in Moscow, Idaho, where adult insects were identified, to be sent to UAF upon
completion, where insect tissues were used for stable isotope analysis.
Spawning salmon carcass tissue samples were collected as encountered between site RP-81
(Montana Creek) and FA-184 (Watana Dam) (Figures 3-1, and 3-2). A total of up to 40 tissue
samples per year from a combination of pink, chum, coho, sockeye, and Chinook salmon were
targeted for collection for stable isotope analysis of marine-derived nutrients (MDN). When and
where possible, tissue samples were taken from spawning salmon carcass tissues by excising 2 to
5 g (0.07 to 0.17 oz) of muscle tissue approximately 1 to 3 inches behind the dorsal fin. A total
of 14 carcasses were collected during summer and fall index events for stable isotope analysis
(Table 4.7-1). All samples were preserved in 70 percent ethanol and returned to UAF for further
analysis.
Stable isotope samples were collected non-lethally from fish selected and sampled as part of the
fish diet analysis (Section 4.9) for targeted fish species (juvenile Chinook salmon, coho salmon,
and rainbow trout). A total of up to 8 fish per target species per site were sampled, if present; a
total of 261 samples were collected in 2013 (Table 4.7-1). Tissue samples were obtained by
clipping a small portion (at least 0.25 cm2 [0.04 in2]) of the caudal fin with sterilized sharp
scissors. Caudal fin tissue regenerates rapidly and is unlikely to affect the growth or survival of
large fish; however it may cause a reduction in survival for fish smaller than 50 mm (2 in) FL.
Therefore, fish smaller than this size selected for stable isotope sampling were euthanized, and
used as a whole-fish sample. All samples were preserved in 70 percent ethanol and returned to
UAF for further analysis.
All sample types for stable isotope analysis were oven dried at 60°C (140ºF) to a constant weight
and ground to a homogenous powder. Subsamples of approximately 1-2 mg for algae, 0.3-0.4
mg for OM, and 0.2-0.3 mg for animal tissue were weighed to the nearest 0.001 mg on a micro-
analytical balance and placed into tin capsules. Samples were combusted and analyzed in an
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isotope-ratio mass spectrometer interfaced with an elemental analyzer at the Alaska Stable
Isotope Facility at UAF.
Results of stable isotope analysis will be used in conjunction with the bioenergetics model
(Section 4.7.1) to describe and quantify the energy pathways and trophic relationships supporting
salmonid production in the food web of the study area.
4.7.3. Variances
4.7.3.1. Stable Isotope Site Selection
The Study Plan stated in IP Section 2.11.1.: “Isotope samples will be collected from two of the
River Productivity Study sampling stations in the Middle Susitna River, with three habitat-
specific sampling sites per station, for a total of six sampling sites.” However, as stated in the
Study Plan (April 1 SPD, B-181), it was recommended that AEA sample in all unique
macrohabitat types present at each proposed study station for river productivity sampling in the
Middle River and Lower River segments. As such, stable isotope sampling was expanded from
the three habitat-specific sampling sites to all unique macrohabitat types. During the initial
spring sampling event, stable isotope sampling was conducted at two focus areas in the Middle
River below Devils Canyon (FA-104 [Whiskers Slough] and FA-141 [Indian River]) due to their
importance to anadromous fish. The total number of sites for stable isotope sampling was
therefore increased from six sites to nine sites.
Further consideration by AEA during the spring sampling event indicated that additional
resolution along a gradient of high to low levels of marine derived nutrients (MDN) from
spawning salmon would be valuable. Therefore, supplemental sampling was added to the study
at two additional stations, Montana Creek at RP-81 and FA-184 (Watana Dam), bringing the
total number of sites for stable isotope sampling to sixteen sites. This addition of the
supplemental sampling stations is expected to provide a clearer understanding of any food web
differences that may exist between stations with high and low densities of spawning salmon.
Thus, the addition of these stations will better address the study objective of quantifying the
relative influence of riverine, terrestrial, and marine energy sources to juvenile salmon and the
broader river food web. Full stable isotope sampling efforts have been undertaken at the two
original stations (FA-104 [Whiskers Slough] and FA-141 [Indian River]) as well as the two
supplemental sites (FA-184 [Watana Dam] and RP-81 [Montana Creek]) for each of the three
sampling events during 2013. All stable isotope samples collected from the two original
sampling stations will be analyzed, as described in the Study Plan (RSP Section 9.8.4.9, and IP
Section 2.11). Due to the substantial cost of stable isotope lab analysis, a subset of the samples
from sites at the supplemental stations will be selected for analysis. This subset will be selected
with the goal of minimizing the uncertainty in the stable isotope study results, based on
preliminary results from the original sampling stations. This variance will be incorporated into
the River Productivity Study sampling efforts in the next year of study, to allow for
comparability with 2013 efforts.
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4.7.3.2. Subcutaneous Dye Injection
Fish can move between macrohabitats to enhance their growth rates. To incorporate the
movements of juvenile coho salmon and rainbow trout into the growth rate potential (GRP)
models, the Study Plan stated that biotelemetry data from the Fish Distribution and Abundance
in the Middle and Lower River Study (RSP Section 9.6.4.3.2) would be included in the analysis.
Towards this goal, the April 1 SPD (p. B-199) recommended the following specific approach:
“In consideration of the above, for fish sampled for use in the growth and trophic modeling
studies, we recommend that AEA measure, weigh, and mark the first 50 fish of each target
species and age class captured within each sampled macrohabitat by PIT-tagging to identify the
capture station and date.” In a footnote to this recommendation, it was noted that “PIT tags can
generally be implanted in fish > 60 mm in length and a macrohabitat-specific subcutaneous dye
injection should be used on fish less than 60 mm in length.” The movements and individual
growth trajectories of juvenile coho salmon and juvenile rainbow trout were quantified using PIT
tags. However, smaller (less than 60 mm) fish were not marked with subcutaneous dye because
this would have produced relatively little useful data on movements among macrohabitats or
individual growth rates, while requiring a considerable effort.
Dye marking was judged to be of limited utility for the following reasons. First, the 1- to 2-
month interval between River Productivity Study sampling trips would severely limit the
inferences that could be drawn about habitat use between the initial marking and each recapture.
Even for those fish that were recaptured in the same habitat in which they were marked, it would
not be clear whether they had remained in that habitat for the entire interval, or moved away and
then returned. In contrast, the PIT tag approach operated on a much finer temporal scale,
capable of detecting diel horizontal migrations between macrohabitats. Such fine-scale
movements between habitats have been shown to substantially enhance juvenile coho salmon
growth rates in other Alaskan river systems. Second, dye markings would only be sufficient to
mark groups of fish captured in the same macrohabitat on the same date, not to identify
individuals. Thus, while overall net movements could be determined, this information would not
be interpretable in terms of specific movements by individuals, the more useful metric for the
GRP models. Finally, without the ability to identify individuals, growth trajectories could not be
determined. For these reasons, the dye marking data would be much less useful for GRP model
validation than the PIT tag data. Therefore, the study resources were focused on implementing a
robust PIT tag study to most effectively document the movements and growth of individual fish,
test the GRP models, and accomplish the objectives of the study.
Although data from the PIT tag study were not yet available during the preparation of this report,
the size distribution of coho salmon and rainbow trout captured for stomach content sampling
supported the focus on PIT tagging to quantify movements because most captured fish exceeded
the 60 mm size threshold. Only 24 percent (29/119) of the juvenile coho salmon were less than
60 mm (fork length). Of these small fish, most were close to the size threshold: Seventeen were
55-59 mm and only one fish was less than 50 mm. None of the nine juvenile rainbow trout
captured for stomach content sampling were less than 60 mm (fork length). These data suggest
that the movements documented by the PIT tag study provided a reasonable representation of
movements by the juvenile coho salmon and juvenile rainbow trout populations as a whole.
Therefore, this variance had no effect on the study team achieving the study objective.
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4.8. Generate habitat suitability criteria for Susitna benthic
macroinvertebrate and algal habitats to predict potential
change in these habitats downstream of the proposed dam site
AEA implemented the methods as described in the Study Plan with no variances. In 2013, data
were collected in support of HSC/HSI models as described in Section 4.4.1. Approximately 300
Hess samples were collected with depth, velocity, and substrate composition measurements
(Table 4.8-1). In addition, 150 samples of LWD (“snags”) were collected with depth, velocity,
and surrounding substrate composition estimates, and 1,745 rock locations taken for composite
algae samples recorded depth and velocity (Table 4.8-1). Curve and model development will
occur in the next year of study.
4.8.1. Variances
No variances from the methods described in the Study Plan (RSP Section 9.8.4.10.) occurred
during the 2013 study season.
4.9. Characterize the invertebrate compositions in the diets of
representative fish species in relationship to their source
(benthic or drift component)
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.9.1.).
In support of the bioenergetics modeling (Objective 5, Section 4.7), stomach contents were
collected from juvenile coho salmon, juvenile Chinook salmon, and rainbow trout. For the 2013
field season, rainbow trout smaller than 120 mm (4.7 in) fork length were considered
“juveniles”, and larger fish were considered “adults”. The fish collections were coordinated with
the Fish Distribution and Abundance in the Middle and Lower Susitna River Study (Study 9.6.)
and methods used for collecting fish specimens are described in that study’s Initial Study Report
(ISR Study 9.6). Fish sampling was to take place within one week of River Productivity index
event sampling, in order to ensure that fish diet data coincided with food prey availability data,
i.e., the benthic sampling (Section 4.4) and drift sampling (Section 4.5).
Fish sampling was attempted at all study sites, although logistical difficulties in sampling
coordination prevented all sites from being sampled during all index events, especially during
spring (Table 4.9-2). These difficulties were largely due to lack of overlap in sampling
schedules, resulting in fish collections taking place more than one week after River Productivity
sampling events, and lack of overlap of sampling sites according to macrohabitat type, resulting
in different locations than those visited by River Productivity crews. These difficulties were
addressed to substantially improve sampling coverage during summer, and to achieve full
coverage of the 21 study sites during fall. River Productivity index event times were rescheduled
to coincide with fish distribution and abundance fish sampling events (ISR Study 9.6). In
addition, River Productivity crews deployed up to 12 baited minnow traps (approximately 90
minute set times) within the sampling sites where no overlap in sampling sites during collection
efforts was initially identified for Spring and Summer sampling, and further increased that effort
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with minnow traps set at all sites in Fall sampling. Target species were often rare or absent from
catches at some sites, especially FA-173 (Stephan Lake Complex) and FA-184 (Watana Dam),
thus this sampling effort resulted in 260 samples total for 2013 (Tables 4.9-1 through 4.9-4).
Stomach contents were collected from the first eight fish per target species and age class that
were captured at each sampling site during the index period (Tables 4.9-2 through 4.9-4 ). Fish
were anesthetized with clove oil, measured for fork length (mm), weighed (g), and their stomach
contents were flushed with a 10-mL (0.3 oz) syringe assembly (Meehan and Miller 1978).
Stomach contents were flushed into a Whirl-Pak bag and preserved in at least 70 percent ethanol.
Scale samples and tissue samples for stable isotope analysis were taken from the fish at this time
as well, using methods detailed in Section 4.7.
Stomach content samples were examined under a dissecting microscope in the laboratory at
UAF. Invertebrate prey were identified to life stage (i.e., larva, pupa, nymph, or adult) and
family when possible, or otherwise to the lowest possible taxonomic level. Invertebrates were
categorized as aquatic or terrestrial based on their taxon and life stage (Merritt et al. 2008). Fish
prey were identified to species when possible, or otherwise to the lowest possible taxonomic
level. The body lengths of intact prey organisms were measured to the nearest millimeter, and
the lengths of partially digested prey were estimated based on intact individuals of the same
taxon that appeared similar in size. The dry mass of prey organisms was determined from
length-weight regression relationships developed for Alaskan aquatic invertebrates (M. Wipfli,
UAF, unpublished data; Wipfli 1997). All stomach contents were archived in 95 percent ethanol
for future verification.
4.9.1. Variances
4.9.1.1. Processing of empty stomach samples
The Study Plan stated in IP Section 2.8.1 that “A fish that is lavaged and found to have an empty
stomach will be replaced by the next fish of that species and age class that is captured.” This
approach was found to be unworkable in the field. Field personnel were not confident that they
could determine whether a stomach contents sample was empty of very small food items (e.g.,
zooplankton or insect parts) in the field without the aid of a microscope. Further, some samples
that appeared to contain food in the field actually contained only non-food items such as plant
parts and debris. Therefore, field crews did not attempt to determine whether stomach content
samples were empty in the field. Instead, stomach contents were collected from the first eight
fish per target species and age class that were captured at each sampling site, and all of these
samples were analyzed in the laboratory. This variance helped in eliminating uncertainties in
sample collection by standardizing the sampling effort and decision process, thus allowing the
study crew achieve the study objective. While the approach does present the risk of accepting
samples that may consist solely of non-food items, it also prevents the potential to discard viable
samples. This variance will be incorporated into the River Productivity Study sampling efforts
in the next year of study, to allow for comparability with 2013 efforts.
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4.9.1.2. Dry mass measurements
The method of determining the mass of prey items in stomach contents was changed from the
method in the Study Plan to improve accuracy and better achieve the study objective. The Study
Plan (IP Section 2.8.2) stated that the blotted wet weight of each prey category would be
recorded to the nearest 0.1 g using an electronic balance, and a representative subset of prey
items in each category would be measured to the nearest millimeter and weighed to the nearest
0.01 g. Instead, the body lengths of intact prey organisms were measured to the nearest
millimeter, and the lengths of partially digested prey were estimated based on intact individuals
of the same taxon that appeared similar in size. The dry mass of prey organisms was determined
from length-weight regression relationships derived from the literature (e.g., Rogers et al. 1976,
1977; Smock 1980; Benke et al. 1999; Johnston and Cunjak 1999; Sabo et al. 2002) and from
recent studies of Alaskan stream invertebrates (M. Wipfli, UAF, unpublished data). This change
improved the accuracy of diet composition estimates in two ways: 1) by correcting for partial
digestion, to estimate the mass of organisms when they were initially consumed, and 2) by
eliminating potential bias resulting from differential digestion rates of prey taxa with different
amounts of schleritization (e.g., chironomid larvae versus coleopteran adults). This change also
standardized the estimation of invertebrate biomass between specimens collected from the
environment (e.g., with the Hess sampler) and those collected from fish stomachs (Wipfli 1997).
This adjustment therefore increased accuracy, reduced sampling bias, and provided a standard
methodology for estimating biomass while achieving the study objective. This variance will be
incorporated into the River Productivity Study sampling efforts in the next year of study, to
allow for comparability with 2013 efforts.
4.10. Characterize organic matter resources (e.g., available for
macroinvertebrate consumers) including coarse particulate
organic matter, fine particulate organic matter, and suspended
organic matter in the Middle and Lower Susitna River
AEA implemented the methods as described in the Study Plan with no variances. Organic matter
is contributed from the terrestrial environment as both fine particulate organic matter (FPOM)
and coarse particulate organic matter (CPOM). FPOM includes particles ranging from 0.45 to
1000 µm in size, and can occur in the water column as seston, or be deposited in lotic habitats as
fine benthic organic matter (FBOM) (Wallace and Grubaugh 1996). CPOM is defined as any
organic particle larger than 1 mm in size (Cummins 1974). In order to quantify the organic
matter available in the Susitna River for river productivity, CPOM and FPOM (specifically
FBOM) were collected directly from all benthic macroinvertebrate sampling, in Hess and Petite
Ponar samples and drift net samples (Objective 2, Section 4.4; Objective 3, Section 4.5).
Therefore, 301 Hess samples, 85 Ponar grabs, and 104 drift samples were processed for organic
matter content (Tables 4.4-2, 4.5-1, and 4.6-1 through 4.6-3).
To streamline the collection efforts, Hess sampling devices, and sieves used to rinse and retain
sample contents from Hess and grab samplers possessed a net mesh size of 250 µm in order to
retain CPOM particles and FBOM in the 250–1,000 µm size range for analysis. All organic
debris collected within each Hess and grab sample was retained with the sample and preserved in
95 percent ethanol. Suspended FPOM (seston) was collected from material in invertebrate drift
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samples, using drift nets with a 250-µm mesh size in order to retain CPOM particles as well as
FBOM in the 250–1,000 µm size range for analysis. All organic debris collected within each
drift sample was retained with the sample and preserved with 95 percent ethanol.
Processing of benthic macroinvertebrates involved subsampling to acquire a 300-organism fixed-
count (±20 percent) subsample. All invertebrates were removed from debris with the aid of a
dissecting microscope (7-45x), and sorted debris was retained in a labeled, 60-ml (2 oz) bottle
and stored for later for QA/QC assessment and, for Hess samples, organic matter analysis.
Organic matter retained from subsampling after organism sorting and processing was separated
from inorganic material, rinsed through 1-mm and 250-µm nested sieves, to separate CPOM and
FPOM components of the detritus, oven-dried (60°C [140°F]), and weighed. Dried components
were combusted and reweighed to determine ash free dry mass (AFDM) weights.
4.10.1. Variances
No variances from the methods described in the Study Plan (IP Section 2.4, and April 1 SPD [B-
189])occurred during the 2013 study season.
4.11. Estimate benthic macroinvertebrate colonization rates in the
Middle Susitna River Segment under pre-Project baseline
conditions to assist in evaluating future post-Project changes
to productivity in the Middle Susitna River.
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (Section 4.11.1).
In order to assess the influences of turbidity and temperature on the benthic community
colonization rates, the first year of a two-year field study was conducted in 2013 to estimate
potential benthic macroinvertebrate colonization rates for four different habitat types that reflect
these conditions in the Susitna River. Due to the difficulty of isolating each of these conditions
under natural conditions, colonization was examined under turbid/warm, clear/warm, turbid/cold,
clear/cold conditions. “Warm” temperatures were defined as 13°C or higher, and “cold”
temperatures were less than 13°C. Four sampling locations reflecting these condition
combinations were established in FA-104 (Whiskers Slough) (Figure 4.2-4), following a review
of 2012 study results, and from consulting with crews from the Instream Flow Study (Study 8.5),
who had surveyed multiple Focus Areas in the Middle Segment, for possible candidate sites with
clear/cold and turbid/cold conditions. The clear/warm site (RP-HD-1) was established in
Whiskers Slough, downstream of Whiskers Creek (Figure 4.2-4; Appendix B, Figure B-5). The
clear/cold site (RP-HD-2) was located in Whiskers Slough near the head, in proximity to side
slough site RP-104-2 (Figure 4.2-4; Appendix B, Figure B-6). The turbid/cold site (RP-HD-3)
was located at the upstream end of the side channel site RP-104-5, near the outflow of a small
side slough, where colder water seeped out into the more turbid waters of the main channel
(Figure 4.2-4; Appendix B, Figures B-9 and B-10). The turbid/warm site, RP-HD-4 was
established upstream of FA-104 (Whiskers Slough) along the shoreline of a side channel (Figure
4.2-4; Appendix B, Figure B-10).
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Sets of three Hester-Dendy multiplate samplers (Figure 4.4-1) were deployed incrementally for
set periods of colonization time (e.g., 8, 6, 4, 2, and 1 week[s]), beginning on August 1 and 2,
2013, and then pulled simultaneously at the conclusion of the colonization period (September 20,
21, and 27, 2013) (Table 4.11-1). Hester-Dendy sets were deployed at two depths (1 ft and 2 ft)
at fixed sites along the channel bed (Table 4.11-2). The location, depth, velocity (both 60
percent of depth and near-bed measurements), PAR levels, and turbidity were measured both
during the deployments of each set, as well as during the retrievals.
Many samplers located at sites in main channel macrohabitats (RP-HD-3 and -4) were subjected
to fluctuating water levels, and were exposed for short periods of time during the 8-week test run
(Table 4.11-2). Flows rapidly declined during the last two weeks of the test run, resulting in
large amounts of sediment deposited at RP-HD-3, both burying and exposing all samplers at that
site (Figure 4.11-1). All samplers at RP-HD-3 were retrieved on September 20, 2013; to prevent
additional losses due to dewatering, all sampler sets were retrieved from RP-HD-4 the following
day, cutting the exposure times short by one week (Table 4.11-3). The clear water colonization
test sites located in Whiskers Slough did not experience water level reductions as severe, and the
final 1-week sampler sets were successfully deployed and retrieved at those sites (Tables 4.11-1
through 4.11-3).
A total of 105 Hester-Dendy samplers were collected during the 2013 test effort (Table 4.11-2),
and were sent to Ecoanlysts, Inc. in Moscow, Idaho for processing. Benthic macroinvertebrate
processing protocols are identical to those used in Objective 2 (Section 4.4). Specific details on
sampling protocols are provided in the Implementation Plan (R2 2013c).
4.11.1. Variances
The Study Plan stated in IP Section 2.9.1: “All Hester-Dendy samplers will be pre-conditioned
prior to deployment by being placed for 4 weeks in the Susitna River (preferably at a project
base camp) and then air-dried.” Due to manufacturing time and shipping time, the order of 120
Hester-Dendy samplers arrived shortly before the time at which the first sets, which remained in
the river for eight weeks, needed to be deployed. As such, Hester-Dendy samplers were not pre-
conditioned prior to their deployment. Pre-conditioning of the substrates may have better
simulated the conditions of natural substrates in the shoreline areas, which are often inundated
and then exposed, but may still exhibit desiccated organic layers of an epilithic film, which
would encourage initial colonization (Mackay 1992). As a result, colonization rates during
initial weeks of deployment may experience lower colonization rates, as epilithic growth
develops, which may occur in the first two weeks (Osborne 1983). However, as time accrues,
colonization rates may reach equilibrium, resulting in little difference in colonization in later
periods (6 and 8 weeks). By introducing new, clean, and bare substrates at all stages of the
experiment, all Hester-Dendy samplers were standardized, both in the surface areas each
provided and it the condition in which it was introduced to the river for a start point in
colonization. So, while results from the colonization periods of shorter duration may be
underestimated in comparison to natural substrates, all Hester-Dendy samplers would display
equal base colonization conditions, differing only in the factors of temperature, turbidity, depth,
and velocity that would affect colonization rates. Therefore, the lack of preconditioning would
not prevent an assessment the influences of turbidity and temperature on the benthic community
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colonization rates. This variance will be incorporated into the River Productivity Study sampling
efforts in the next year of study, to allow for comparability with 2013 efforts.
5. RESULTS
5.1. Synthesize existing literature on the impacts of hydropower
development and operations (including temperature and
turbidity) on benthic macroinvertebrate and algal communities.
This synthesis document was completed and is included in Appendix A.
5.2. Characterize the pre-Project benthic macroinvertebrate and
algal communities with regard to species composition and
abundance in the Middle and Lower Susitna River.
Benthic samples collected during the three index events in 2013 were comprised of 271 Hess
samples, 155 LWD (snag) samples, 70 petite Ponar grab samples, and 45 adult emergence traps.
These samples were successfully transported to the contracted taxonomic laboratory in 2013, and
results are pending, upon completion of processing.
Benthic algae samples collected during the three index events in 2013 were comprised of 309
composite algae samples. These samples were successfully transported to the contracted
taxonomic laboratory in 2013, which tested samples to determine chlorophyll-a and ash free dry
mass (AFDM) values. Laboratory test results were used to calculate the average chlorophyll-a
(mg/m2) and ADFM (g/m2) for each site for each index event period (Table 5.2-1; Figures 5.2-1
through 5.2-10).
Data developed in support of the ISR is available for download at
http://gis.suhydro.org/reports/isr (ISR_9_8_RIVPRO_AlgaeLabResults). Overall chlorophyll-a
levels sampled in 2013 ranged from an average of 0.04 mg/m2 (near the minimum detectable
testing level) at main channel sites RP-184-3 and RP-81-3 during summer and fall index events,
to 65.7mg/m2 at side slough site RP-104-2 during the fall index event (Table 5.2-1). Estimates
of AFDM ranged from an average of 0.13 g/m2 at main channel site RP-104-3 during the spring
index event, to 17.89 g/m2 at the side channel site RP-173-3 during the summer index event. In
general, chlorophyll-a and AFDM estimates were lower in mainstem macrohabitats than in other
macrohabitat types, especially off-channel habitats (side sloughs, upland sloughs) (Figures 5.2-3
through 5.2-10).
5.3. Estimate drift of benthic macroinvertebrates in selected
habitats within the Middle and Lower Susitna River to assess
food availability to juvenile and resident fishes.
Drift samples collected during the three index events in 2013 were comprised of 92 drift
samples, and 85 plankton tow samples. These samples were successfully transported to the
contracted taxonomic laboratory in 2013, and results are pending completion of processing.
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5.4. Conduct a feasibility study in 2013 to evaluate the suitability of
using reference sites on the Talkeetna River to monitor long-
term Project-related change in benthic productivity.
Benthic and drift samples were collected from three sampling sites established in the Talkeetna
River, in conjunction with sampling during the three index event periods in 2013 at the 20
Susitna River study sites. A total of 30 Hess samples, 15 Ponar grab samples, 45 composite
algae samples, 12 drift samples, and 10 plankton tows were collected from the Talkeetna sites.
Benthic macroinvertebrate samples were successfully transported to the contracted taxonomic
laboratory in 2013, and results are pending completion of processing.
Composite algae samples were successfully transported to the contracted taxonomic laboratory
in 2013, which tested samples to determine chlorophyll-a and AFDM values. Laboratory test
results were used to calculate the average chlorophyll-a (mg/m2) and ADFM (g/m2) for each site
for each index event period (Table 5.2-1; Figures 5.2-11 and 5.2-12). Data developed in support
of the ISR is available for download at http://gis.suhydro.org/reports/isr
(ISR_9_8_RIVPRO_AlgaeLabResults). Chlorophyll-a levels ranged from an average of 0.39
mg/m2 at side channel site RP-TKA-1 during the fall index event, to 81.3 mg/m2 at side slough
site RP-TKA-3 also during the fall index event (Table 5.2-1; Figure 5.2-11). Estimates of
AFDM ranged from an average of 0.64 g/m2 at side channel site RP-TKA-1 during the fall index
event, to 19.2 g/m2 at side slough site RP-TKA-3 also during the fall index event (Figure 5.2-12).
Fall index event estimates for AFDM at the upland slough site RP-TKA-2 averaged 242.6 g/m2,
a large departure from Susitna River algal test results. The preferred epilithic and epidendric
substrates were not present at RP-TKA-2 during the fall index event for sampling chlorophyll-a
and AFDM; therefore, composite samples were taken from the soft bottom substrate with the
algae delimiter. High organic matter content in the sampled sediments would explain the high
AFDM estimates at this site. In general, chlorophyll-a and AFDM estimates were higher at the
side slough site than in the side channel and upland slough sites (Figures 5.2-11 and 5.2-12).
5.5. Conduct a trophic analysis to describe the food web
relationships within the current riverine community within the
Middle and Lower Susitna River.
The trophic modeling analysis was initiated during the fourth quarter of 2013. However, the
model requires inputs in addition to the data collected by River Productivity field teams. The
additional model inputs include: fish movement data from the Fish Distribution and Abundance
in the Lower and Middle Susitna River Study (ISR Study 9.6), fish stomach content and scale
aging analyses, temperature logging data, and drift sample results. The trophic modeling
analysis will proceed as soon as the necessary field data and laboratory data become available.
In 2013, tissue samples were collected for stable isotope analysis (SIA) from multiple study
components, including benthic macroinvertebrates, benthic algae, benthic organic matter,
invertebrates and organic matter in drift samples, salmon carcasses, and fin clips from fish (Table
4.7-1). Most sample components were processed and submitted for analysis in an isotope-ratio
mass spectrometer at the Alaska Stable Isotope Facility at UAF. Additional SIA testing on
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emergent adult insects is pending completion of processing of emergent trap samples by the
contracted taxonomic laboratory, and transport to UAF for testing.
5.6. Develop habitat suitability criteria for Susitna benthic
macroinvertebrate and algal habitats to predict potential
change in these habitats downstream of the proposed dam site.
Depth, velocity, and substrate composition measurements were taken in conjunction with Hess
samples, LWD (“snags”) samples, and composite algae samples collected in 2013 (Section 5.2).
Corresponding benthic macroinvertebrate results required for HSC/HSI development are pending
completion of processing by the contracted taxonomic laboratory.
5.7. Characterize the invertebrate compositions in the diets of
representative fish species in relationship to their source
(benthic or drift component).
The juvenile Chinook salmon, juvenile coho salmon, and rainbow trout sampled in this study
consumed a wide variety of prey items, including benthic macroinvertebrates, terrestrial
invertebrates, zooplankton, salmon eggs, and small fish. Detailed analysis and summary of the
stomach content data is ongoing.
5.8. Characterize organic matter resources (e.g., available for
macroinvertebrate consumers) including coarse particulate
organic matter, fine particulate organic matter, and suspended
organic matter in the Middle and Lower Susitna River.
Organic matter samples were successfully transported to the contracted taxonomic laboratory in
2013. Organic matter results are pending completion of processing.
5.9. Estimate benthic macroinvertebrate colonization rates in the
Middle Susitna Segment under pre-Project baseline conditions
to assist in evaluating future post-Project changes to
productivity in the Middle Susitna River.
Hester-Dendy samples were successfully transported to the contracted taxonomic laboratory in
2013, and results are pending completion of processing.
6. DISCUSSION
At the time of writing this ISR, the River Productivity Study had not yet received the laboratory
results from a majority of the samples collected in 2013. One component, benthic algae
sampling, has been fully processed by the analytical laboratory, and results were available for
inclusion in this report. All samples collected at all sites during each of the three sampling index
events have corresponding results of chlorophyll-a and AFDM values, and that collection effort
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has been determined as complete and adequate for 2013. However, the results for Hess samples,
Ponar Grab samples, LWD (“snag”) samples, emergence trap samples, drift net samples,
plankton tow samples, the organic matter components of benthic samples, and Hester-Dendy
samples for colonization study are all pending completion of their processing by the taxonomic
laboratory. Processing is scheduled for completion by April 2014.
As such, the adequacy of data collection in 2013 cannot be fully assessed until results from the
samples are received in 2014, and data analyses are conducted thereafter. Independent of sample
results, three study objectives have been identified as having sampling deficiencies, or gaps in
data collection in 2013: emergence trap sampling (Section 4.4), fish collection for stomach
contents (Section 4.9), and Hester-Dendy sampling for colonization (Section 4.11).
The Study Plan states that “Adult aquatic insect emergence mass is a product of aquatic insect
production from the stream, and is therefore a good surrogate for actual production. To measure
insect emergence, floating emergence trap samplers will be deployed, with one trap per site” (IP
Section 2.6). Collection efforts in 2013 found that the traps were prone to damage from wildlife,
and were stranded on shorelines due to rapid changes in flow levels or from disturbances by
boating activities (Section 4.4.1.). Due to the prolonged set times of approximately two weeks,
the exact timing occurrence of a disturbance within that period was unknown, making any
sample data that could be retrieved from the trap bottle qualitative, since the total sampling time
was in question. To resolve this concern, emergence trap methods should be reviewed and
refined for efforts in the next year of study. At a minimum, trap designs and deployment
methods should be modified to better withstand flow and stage changes. In previous Alaskan
studies, emergence traps have been deployed on smaller streams or water bodies with lower flow
velocities. A review of the 2013 results when they are received from the processing laboratory
in 2014, should provide additional information about the efficiency of the traps for collecting
emerging adult insects from specific macrohabitat sites with higher velocities, namely the
mainstem sites.
Fish collections for stomach contents, scales, and stable isotopes are required by the Study Plan,
as detailed in RSP Section 9.8.4.11 and IP Sections 2.7, 2.8, and 2.11. The fish collection
methods and scheduled sampling efforts in 2013 were coordinated with the Fish Distribution and
Abundance in the Middle and Lower Susitna River Study (Study 9.6). The River Productivity
Study protocol required that fish collections be conducted in the same macrohabitat site
locations, and within one week of the River Productivity index events. Initial sampling
coordination for the spring index event did not meet these requirements, due to distinct gaps in
sampling schedules and the ongoing establishment and definition of study sampling locations
that would overlap between the two studies. As a result, fish collections for River Productivity
Study needs were missed at six out of 20 sites during the spring index event. In response, the
River Productivity Study crew scheduled the summer and fall index event sampling in
coordination with ISR Study 9.6 fish collection efforts to help ensure samples were collected
within a week of each other. The River Productivity Study crew also increased its efforts by
supplementing fish collection with baited minnow traps at selected sites during the spring and
summer index events, and at all sites during the fall index event (Tables 4.9-2 through 4.9-4).
The River Productivity Study conducted all fish collections at study station RP-81 (Montana
Creek) in the Lower Susitna River. Originally established in conjunction with anticipated Fish
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Distribution and Abundance sampling activities on the Lower Susitna River around the Montana
Creek mouth area (Section 4.2.4.1.), lack of land access prevented the deployment of a rotary
screw trap near the creek mouth, and the trap was located 2.2 miles upstream in Montana Creek
(ISR Study 9.6, Section 4.1.7.2). This prevented the use of fish from the trap for ISR 9.8 fish
samples. As a result, the River Productivity crew deployed minnow traps at all sites except the
split main channel site, where they would have been less effective in the higher velocities.
Numbers of fish collected in 2013 were lower than expected; FDA efforts at several of the River
Productivity sites did not capture juvenile salmonids. Sampling at FA-173 (Stephan Lake
Complex) and FA-184 (Watana Dam) did not capture any of the targeted species/lifestages, and
sampling efforts in the main channel macrohabitat sites produced limited results as well (Tables
4.9-1 through 4.9-2). Given the gaps in collection coverage in 2013, coordination efforts and
fish collection timing and locations requirements will be reviewed and refined for efforts in the
next year of the study. River Productivity Study and Fish Distribution study efforts will
coordinate schedules pre-field season to maximize both site and scheduling overlaps and
facilitate collection of useable target fish. Additional options may include relaxing the collection
requirements for timing (within a week’s time) and simply matching the macrohabitat type in a
Focus Area as opposed to exact site locations. Lastly, no coho salmon or rainbow trout were
observed for fish sampling efforts above Devils Canyon in 2012 (HDR 2013) or in 2013 (ISR
Study 9.6, Sections 5.1.1.3 and 5.1.1.12). Due to the lack of observations/collections of the
target fish species (see also Study 9.6 ISR Section 5.1.2), the feasibility of collecting sufficient
numbers of target species at FA-173 (Stephan Lake Complex) and FA-184 (Watana Dam) will
be revisited and a decision will be made as to eliminate these sites from the models or utilize a
different target species at these locations for ISR 9.8 models.
Benthic macroinvertebrate colonization rates were examined in 2013 using an experimental
design to determine the effect of turbidity and temperature on colonization. The Study Plan
states in RSP Section 9.8.4.9 that , “In order to assess the influences of turbidity and temperature
on the benthic community colonization rates, a field study will be conducted for both study
years. The field study was to estimate potential benthic macroinvertebrate colonization rates for
four different habitat types that reflect these conditions in the Susitna River.” The four sites
established for this experiment required different levels of turbidity (clear or turbid), temperature
(cool or warm), and depth (1- and 2- foot depth). Controlling for all three of these factors
affected the occurrence of other confounding factors, velocity and substrate, that are equally, if
not more, important to colonization. The site that required cool and clear waters was located in
the side slough habitat, where upwelling ground waters supplied those conditions, but the habitat
itself was a low velocity pool, with a cobble bottom that was layered in fine sediments. Sites
with higher velocities were often lacking in depths of over 1 foot, and were therefore unsuitable
for the required parameters. Due to the number of confounding factors involved, it may be
difficult to isolate differences in colonization rates to different temperature and turbidity
conditions. Colonization sampling sites established in 2013 were essentially placed at three of
the five sampling sites established by the River Productivity Study for benthic and drift sampling
(Figure 4.2-4.), sampling main channel, side channel, side slough above tributary mouth
influence, and side slough below tributary mouth influence habitats. Therefore, a modification is
proposed to investigate the overall differences in colonization rates and compositions between
the five macrohabitat types within River Productivity sites in the next year of the study.
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7. COMPLETING THE STUDY
[As explained in the cover letter to this draft ISR, AEA’s plan for completing this study will be
included in the final ISR filed with FERC on June 3, 2014.]
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9. TABLES
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Table 4.2-1. Locations and descriptions of Focus Areas selected as sampling stations for the River Productivity study in the Lower and Middle River Segments of the
Susitna River. “X” indicates site established at that habitat type, “(x)” indicates no site established at that habitat type.
Focus Area ID /
RivProd
ID 1
Common
Name
River
Productivity
Study Use Description
Geomorphic
Reach
Location (PRM)
Area
Length
(mi)
Habitat Types Present Additional Sampling Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Beaver Complex Stable Isotopes Colonization Study Upstream Downstream Focus
Area-184
Watana
Dam
Study Station
(3 sites)
Area approximately 1.4
miles downstream of
dam site
MR-1 185.7 184.7 1.0 X X X X
Focus
Area-173
Stephan
Lake,
Complex
Channel
Study Station
(4 sites), Storm
Event Site
Wide channel near
Stephan Lake with
complex of side
channels
MR-2 175.4 173.6 1.8 X X X X (x)2
Focus
Area-141 Indian River Study Station
(4 sites)
Area covering Indian
River and upstream
channel complex
MR-6 143.4 141.8 1.6 X X X X (x) X
Focus
Area-104
Whiskers
Slough
Study Station
(5 sites), Storm
Event Site
Whiskers Slough
Complex MR-8 106.0 104.8 1.2 X X X3 X X X X
RP-81 Montana
Creek Area
Study Station (4
sites)
Area nearby the mouth
of Montana Creek LR-2 82 81 1.0 X X X X X (x) X
TKA Talkeetna
River
Reference
Station
(3 sites)
Talkeetna River, above
the Clear Creek
confluence
N/A 9.3 8.5 0.8 (x) X X X (x)
Notes:
1 Focus Area identification numbers (e.g., Focus Area 184) represent the truncated Project River Mile (PRM) at the downstream end of each Focus Area.
2 Upland Slough on CIRI lands, considered non-navigable waters, and access not permitted
3 Tributary Mouth macrohabitat too limited for index event sampling activities; sampling conducted in side slough immediately below the mouth.
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Table 4.4-1. Sampling Stations and Seasonal Sampling Event dates of collection for the River Productivity study in the
Lower and Middle River Segments of the Susitna River, and the Talkeetna River.
Seasonal Sampling Event
Station Spring 2013 Summer 2013 Fall 2013
FA-184 (Watana Dam) 7/12 – 7/13 8/20 – 8/21 9/22
FA-173 (Stephan Lake Complex) 7/9 – 7/11 8/19 – 8/20 9/23 – 9/24
FA-141 (Indian River) 6/25 – 6/27 8/17 – 8/18 9/25 – 9/26
FA-104(Whiskers Slough) 6/19 – 6/23 8/12 – 8/13, 8/16 9/28 – 9/30
RP-81 (Montana Creek) 6/29 – 7/1 8/14 – 8/15 10/1 – 10/2
TKA (Talkeetna Reference) 7/17 – 7/18 8/29 10/3
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Table 4.4-2. Benthic macroinvertebrate sample totals for 2013 sampling during three index events (Spr= Spring, Sum=Summer, Fall) and Post-Storm sampling for sites
in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site Macrohabitat Type
Hess Samples Ponar Grab Samples LWD (Snag) Samples
Spr Sum Fall Post-Storm Total Spr Sum Fall Post-Storm Total Spr Sum Fall Post-Storm Total
RP-184-1 Tributary Mouth 5 5 5 15 5 2 3 10
RP-184-2 Side Channel 5 5 5 15 1 1
RP-184-3 Main Channel 5 5 5 15 RP-173-1 Tributary Mouth 5 5 5 15 2 3 1 6
RP-173-2 Main Channel 5 5 5 15 RP-173-3 Side Channel 5 5 5 15 3 3
RP-173-4 Side Slough 5 5 2 5 17 5 5 5 5 20 1 2 5 8
RP-141-1 Tributary Mouth 5 5 5 15 3 5 5 13
RP-141-2 Side Channel 5 5 10 5 5 5 1 6
RP-141-3 Mult Split Main Channel 5 5 5 15 RP-141-4 Upland Slough 5 4 3 12 5 5 5 15 3 4 5 12
RP-104-1 Side Slough 5 5 5 15 2 5 5 12
RP-104-2 Side Slough 5 5 2 5 17 5 5 3 5 5 5 18
RP-104-3 Main Channel 5 5 5 15 RP-104-4 Upland Slough 5 5 5 15 5 5 3 13
RP-104-5 Side Channel 5 5 5 15 2 5 7
RP-81-1 Upland Slough 5 5 5 5 10 5 2 5 12
RP-81-2 Tributary Mouth 5 5 5 15 5 5 5 15
RP-81-3 Split Main Channel 5 5 5 15 2 2 4
RP-81-4 Side Channel 5 5 5 15 5 5 5 15
Totals 90 89 82 10 271 20 20 25 5 70 41 54 55 5 155
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Table 4.4-3. Adult emergence traps deployment locations with install and removal dates, and count of number of
collection visits with the number of successful samples collected in2013.
Station Site Install Date Removal Date
Number of
Collection Visits
Number of
Samples Collected
RP- 81 RP-81-1 7/1/2013 10/1/2013 4 3
(Montana Creek) RP-81-2 6/30/2013 10/1/2013 4 1
RP-81-3 6/29/2013 10/3/2013 4 4
RP-81-4 6/30/2013 10/3/2013 4 3
FA-104 RP-104-1 6/23/2013 9/27/2013 4 4
(Whiskers Slough) RP-104-2 6/19/2013 9/27/2013 4 3
RP-104-3 6/21/2013 9/30/2013 4 4
RP-104-4 6/23/2013 9/28/2013 4 4
RP-104-5 6/21/2013 9/28/2013 4 2
FA-141 RP-141-1 6/25/2013 9/25/2013 3 1
(Indian River) RP-141-2 6/25/2013 9/26/2013 3 2
RP-141-3 6/27/2013 9/25/2013 3 1
RP-141-4 6/27/2013 9/26/2013 3 1
FA-173 RP-173-1 7/11/2013 9/23/2013 3 2
(Stephan Lake Complex) RP-173-2 7/29/2013 9/23/2013 2 2
RP-173-3 7/11/2013 9/23/2013 2 1
RP-173-4 7/10/2013 9/24/2013 3 2
FA-184 RP-184-1 7/13/2013 9/22/2013 3 2
(Watana Dam) RP-184-3 7/12/2013 9/22/2013 3 3
Totals 64 45
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Table 4.4-4. Composite algae sample totals for 2013 sampling during three index events (Spr= Spring, Sum=Summer,
Fall) and Post-Storm sampling for sites in the Middle and Lower River Segments of the Susitna River, and Talkeetna
(TKA) River for the River Productivity Study.
Site Macrohabitat Type
Composite Algae Samples
Spr Sum Fall Post-Storm Total
RP-184-1 Tributary Mouth 5 4 5
14
RP-184-2 Side Channel 5 5 5
15
RP-184-3 Main Channel 5 5 5
15
RP-173-1 Tributary Mouth 5 5 5
15
RP-173-2 Main Channel 5 5 5
15
RP-173-3 Side Channel 5 5 5
15
RP-173-4 Side Slough 5 5 5 5 20
RP-141-1 Tributary Mouth 5 5 5
15
RP-141-2 Side Channel 5 5 5
15
RP-141-3 Mult Split Main Channel 5 5 5
15
RP-141-4 Upland Slough 5 5 5
15
RP-104-1 Side Slough 5 5 5
15
RP-104-2 Side Slough 5 5 5 5 20
RP-104-3 Main Channel 5 5 5
15
RP-104-4 Upland Slough 5 5 5
15
RP-104-5 Side Channel 5 5 5
15
RP-81-1 Upland Slough 5 5 5
15
RP-81-2 Tributary Mouth 5 5 5
15
RP-81-3 Split Main Channel 5 5 5
15
RP-81-4 Side Channel 5 5 5
15
Totals 100 99 100 10 309
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Table 4.5-1. Benthic drift and plankton tow sample totals for 2013 sampling during three index events (Spr= Spring,
Sum=Summer, Fall) and Post-Storm for sampling sites in the Middle and Lower River Segments of the Susitna River,
and Talkeetna (TKA) River for the River Productivity Study.
Site Macrohabitat Type
Drift Samples Plankton Tow Samples
Spr Sum Fall Total Spr Sum Fall Post-Storm Total
RP-184-1 Tributary Mouth 2 2 2 6
RP-184-2 Side Channel 2 2 2 6
RP-184-3 Main Channel 2 2 2 6
RP-173-1 Tributary Mouth 2 2 2 6
RP-173-2 Main Channel 2 2 2 6
RP-173-3 Side Channel 2 2
2
5
5
RP-173-4 Side Slough
5 5 5
15
RP-141-1 Tributary Mouth 2 2 2 6
RP-141-2 Side Channel 2 2 2 6
RP-141-3 Mult Split Main Channel 2 2
2
5
5
RP-141-4 Upland Slough
5 5 5
15
RP-141-5* Main Channel
2
2
RP-104-1 Side Slough 2 2 2 6
RP-104-2 Side Slough 2
2
5 5 5 15
RP-104-3 Main Channel 2 2 2 6
RP-104-4 Upland Slough 2
2 5 5 5
15
RP-104-5 Side Channel 2 2
2
5
5
RP-81-1 Upland Slough
2 2 5 5
10
RP-81-2 Tributary Mouth 2 2 2 6
RP-81-3 Split Main Channel 2 2 2 6
RP-81-4 Side Channel 2 2 2 6
RP-81-5* Side Channel 2 2 2 6
Totals 36 34 28 92 20 25 35 5 85
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Table 4.6-1. Benthic macroinvertebrate sample totals for 2013 sampling during three index events (Spr= Spring,
Sum=Summer, Fall) for sites in the Talkeetna River (TKA) for the River Productivity Study.
Site
Macro-habitat
Type
Hess Samples Ponar Grab Samples
Spring Summer Fall Total Spring Summer Fall Total
RP-TKA-1 Side Channel 5 5 5 15 RP-TKA-2 Upland Slough 5 5 5 15
RP-TKA-3 Side Slough 5 5 5 15
Totals: 10 10 10 30 5 5 5 15
Table 4.6-2. Composite algae sample totals for 2013 sampling during three index events (Spr= Spring, Sum=Summer,
Fall) for sites in the Talkeetna (TKA) River for the River Productivity Study.
Site Macro-habitat Type
Algae Samples
Spring Summer Fall Total
RP-TKA-1 Side Channel 5 5 5 15
RP-TKA-2 Upland Slough 5 5 5 15
RP-TKA-3 Side Slough 5 5 5 15
Totals: 15 15 15 45
Table 4.6-3. Benthic drift and plankton tow sample totals for 2013 sampling during three index events (Spr= Spring,
Sum=Summer, Fall) for sites in the Talkeetna (TKA) River for the River Productivity Study.
Site
Macro-habitat
Type
Drift Samples Plankton Tow Samples
Spring Summer Fall Total Spring Summer Fall Total
RP-TKA-1 Side Channel 2 2 2 6 RP-TKA-2 Upland Slough 5 5 10
RP-TKA-3 Side Slough 2 2 2 6
Totals: 4 4 4 12 0 5 5 10
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Table 4.7-1. Itemized listing of sample components and the maximum potential number of samples possible for collection for Stable Isotope Analysis from the four
sampling stations (16 sites total) in each study year in the Middle and Lower River Segments of the Susitna River for the River Productivity Study, and the actual
number of samples collected and analyzed in 2013.
Category Component Sites Seasons Samples
Maximum Potential Number of Samples Spring Summer Fall
Total Number Analyzed (2013)
Endmembers
Benthic Algae 16 3 3 144 45 48 48 141
Organic Matter - benthic 16 3 3 144 45 48 48 141
Organic Matter - drift 16 3 2 96 30 32 32 94
Salmon carcass - - 40 40 0 8 6 14
Invertebrates
Benthic- grazers 16 3 3 144 48 48 49 145
Benthic- collectors 16 3 3 144 34 33 29 96
Benthic- shredders 16 3 3 144 30 48 39 117
Benthic- predators 16 3 3 144 48 48 35 131
Terrestrial Drift 16 3 2 96 27 36 39 102
Emergents 16 3 1 48 N/A* N/A* N/A* N/A*
Fish
Chinook salmon - juveniles 16 3 8 384 36 46 21 103
Coho salmon - juveniles 16 3 8 384 25 47 46 118
Rainbow trout - juveniles 16 3 8 384 9 0 0 9
Rainbow trout - adults 16 3 8 384 4 17 10 31
Total 2,680 381 459 402 1242
* Emergence sample results were not fully processed and enumerated by the reporting cutoff date of October 31, 2013.
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Table 4.8-1. Number of Hess, algae, and snag samples collected with associated depth (D), velocity (V), and substrate composition (Sub) measurements for 2013
sampling during three index events (Spr= Spring, Sum=Summer, Fall) in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Site Macro-habitat Type
Hess Samples (D, V, Sub) Algae Samples (D, V) Snag Samples (D, V, Sub)
Spr Sum Fall Post-Storm Total Spr Sum Fall Post-Storm Total Spr Sum Fall Post-Storm Total
RP-184-1 Tributary Mouth 5 4 5 14 25 20 25 70 5 2 3 10
RP-184-2 Side Channel 5 5 5 15 25 25 25 75 1 1
RP-184-3 Main Channel 5 5 5 15 25 25 25 75 RP-173-1 Tributary Mouth 5 5 5 15 25 25 25 75 2 3 1 6
RP-173-2 Main Channel 5 5 5 15 25 25 25 75 RP-173-3 Side Channel 5 5 5 15 25 25 25 75 3 3
RP-173-4 Side Slough 5 5 2 5 17 25 25 25 25 100 1 2 5 8
RP-141-1 Tributary Mouth 5 5 5 15 25 25 25 75 3 5 5 13
RP-141-2 Side Channel 5 5 10 25 25 25 75 5 1 6
RP-141-3 Mult Split Main
Channel 5 5 5 15 25 25 25 75 RP-141-4 Upland Slough 5 4 3 12 25 25 25 75 3 4 5 12
RP-104-1 Side Slough 5 5 5 15 25 25 25 75 2 5 5 12
RP-104-2 Side Slough 5 5 2 5 17 25 25 25 25 100 3 5 5 5 18
RP-104-3 Main Channel 5 5 5 15 25 25 25 75 RP-104-4 Upland Slough 25 25 50 5 5 3 13
RP-104-5 Side Channel 5 5 5 15 25 25 25 75 2 5 7
RP-81-1 Upland Slough 5 5 25 25 25 75 5 2 5 12
RP-81-2 Tributary Mouth 5 5 5 15 25 25 25 75 5 5 5 15
RP-81-3 Split Main Channel 5 5 5 15 25 25 25 75 2 2 4
RP-81-4 Side Channel 5 5 5 15 25 25 25 75 0 5 5 10
RP-TKA-1 Side Channel 5 5 5 15 25 25 25 75 RP-TKA-2 Upland Slough 25 25 25 75 RP-TKA-3 Side Slough 5 5 5 15 25 25 25 75
Totals 100 98 92 10 300 575 545 575 50 1745 36 54 55 5 150
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Table 4.9-1. Itemized listing of the maximum potential number of fish gut content samples possible for collection for the
River Productivity Study in each study year, and the number of actual samples collected and analyzed in 2013.
Target Species / Lifestage Sites Seasons Samples Maximum Potential Number of Samples Total Number Analyzed
Chinook salmon - juveniles 20 3 8 480 103
Coho salmon - juveniles 20 3 8 480 117
Rainbow trout - juveniles 20 3 8 480 9
Rainbow trout - adults 20 3 8 480 31
Total 1,920 260
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Table 4.9-2. Number of fish collected for fish gut content, scales, and stable isotope tissue samples during the Spring Index Event for each target species / age class from
each sampling site in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Station Sampling site Habitat Type Sampled By Juvenile Chinook Juvenile Coho Juvenile Rainbow Adult Rainbow FDA RivPro
Spring Totals
FA-184
(Watana Dam)
RP-184-1 Tributary Mouth Y 0 0 0 0
RP-184-2 Side Channel Y Y 0 0 0 0
RP-184-3 Main Channel Y 0 0 0 0
FA-173
(Stephan Lake
Complex)
RP-173-1 Tributary Mouth Y Y 0 0 0 0
RP-173-2 Main Channel Y 0 0 0 0
RP-173-3 Side Channel Y Y 0 0 0 0
RP-173-4 Side Slough Y Y 0 0 0 0
FA-141
(Indian River)
RP-141-1 Tributary Mouth Y 8 8 0 1
RP-141-2 Side Channel - - - -
RP-141-3 Mult Split Main
Channel Y 0 0 0 0
RP-141-4 Upland Slough - - - -
FA-104
(Whiskers Slough)
RP-104-1 Side Slough Y 8 0 0 3
RP-104-2 Side Slough Y - - - -
RP-104-3 Main Channel Y 0 0 0 0
RP-104-4 Upland Slough Y - - - -
RP-104-5 Side Channel Y - - - -
RP- 81
(Montana Creek)
RP-81-1 Upland Slough Y 8 8 0 0
RP-81-2 Tributary Mouth Y 12 8* 9 0
RP-81-3 Split Main Channel - - - -
RP-81-4 Side Channel Y 0 0 0 0
Spring Totals 36 24 9 4
* One additional fish was collected for stable isotope tissues.
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Table 4.9-3. Number of fish collected for fish gut content, scales, and stable isotope tissue samples during the Summer Index Event for each target species / age class
from each sampling site in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Station Sampling site Habitat Type Sampled By Juvenile
Chinook Juvenile Coho Juvenile
Rainbow Adult Rainbow FDA RivPro
Summer Totals
FA-184
(Watana Dam)
RP-184-1 Tributary Mouth Y Y 0 0 0 0
RP-184-2 Side Channel Y Y 0 0 0 0
RP-184-3 Main Channel Y 0 0 0 0
FA-173
(Stephan Lake
Complex)
RP-173-1 Tributary Mouth Y Y 0 0 0 0
RP-173-2 Main Channel Y 0 0 0 0
RP-173-3 Side Channel Y Y 0 0 0 0
RP-173-4 Side Slough Y Y 0 0 0 0
FA-141
(Indian River)
RP-141-1 Tributary Mouth Y 5 8 0 8
RP-141-2 Side Channel - - - -
RP-141-3 Mult Split Main
Channel Y 0 0 0 0
RP-141-4 Upland Slough Y* 8 3 0 0
FA-104
(Whiskers Slough)
RP-104-1 Side Slough Y 8 8 0 0
RP-104-2 Side Slough Y 8 9** 0 9
RP-104-3 Main Channel Y 0 0 0 0
RP-104-4 Upland Slough Y 8 8 0 0
RP-104-5 Side Channel Y* 8 8 0 0
RP- 81
(Montana Creek)
RP-81-1 Upland Slough Y 0 0 0 0
RP-81-2 Tributary Mouth Y 1 4 0 0
RP-81-3 Split Main Channel - - - -
RP-81-4 Side Channel Y 0 0 0 0
Summer Totals 46 48 0 17
* Sampling by the FDA study team covered the same macrohabitat types but different sites than the River Productivity sampling at RP-104 (side channel) and
RP-141 (upland slough).
** One less fish was collected for stable isotope tissues.
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Table 4.9-4. Number of fish collected for fish gut content, scales, and stable isotope tissue samples during the Fall Index Event for each target species / age class from
each sampling site in the Middle and Lower River Segments of the Susitna River for the River Productivity Study.
Station Sampling site Habitat Type Sampled By Juvenile
Chinook Juvenile Coho Juvenile
Rainbow Adult Rainbow FDA RivPro
Fall Totals
FA-184
(Watana Dam)
RP-184-1 Tributary Mouth Y 0 0 0 0
RP-184-2 Side Channel Y Y 0 0 0 0
RP-184-3 Main Channel Y Y 0 0 0 0
FA-173
(Stephan Lake
Complex)
RP-173-1 Tributary Mouth Y Y 0 0 0 0
RP-173-2 Main Channel Y Y 0 0 0 0
RP-173-3 Side Channel Y Y 0 0 0 0
RP-173-4 Side Slough Y Y 0 0 0 0
FA-141
(Indian River)
RP-141-1 Tributary Mouth Y Y 6 8 0 2
RP-141-2 Side Channel Y 0 0 0 0
RP-141-3 Mult Split Main
Channel Y Y 0 0 0 0
RP-141-4 Upland Slough Y 0 1 0 0
FA-104
(Whiskers Slough)
RP-104-1 Side Slough Y Y 8 8 0 8
RP-104-2 Side Slough Y Y 2 8 0 0
RP-104-3 Main Channel Y Y 0 0 0 0
RP-104-4 Upland Slough Y Y 1 5** 0 0
RP-104-5 Side Channel Y* Y 3 9 0 0
RP- 81
(Montana Creek)
RP-81-1 Upland Slough Y 1 4 0 0
RP-81-2 Tributary Mouth Y 0 2 0 0
RP-81-3 Split Main Channel Y 0 0 0 0
RP-81-4 Side Channel Y 0 0 0 0
Fall Totals 21 45 0 10
* Sampling by the FDA study team covered the same macrohabitat type but a different site than the River Productivity sampling at RP-104 (side channel).
** One additional fish was collected for stable isotope tissues.
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Table 4.11-1. Colonization study sites in FA-104 (Whiskers Slough), with temperature and turbidity conditions, and deployment and retrieval dates for Hester-Dendy
multiplate sampler sets for the five colonization time periods.
Site Condition 8-Wk 6-Wk 4-Wk 2-Wk 1-Wk
Retrieval
Date
RP-HD-1
(Side Slough) Clear, Warm 8/1/2013 8/16/2013 8/30/2013 9/12/2013 9/20/2013 9/27/2013
RP-HD-2
(Side Slough) Clear, Cold 8/1/2013 8/16/2013 8/30/2013 9/12/2013 9/20/2013 9/27/2013
RP-HD-3
(Side Channel) Turbid, Cold 8/2/2013 8/16/2013 8/30/2013 9/12/2013 - 9/20/2013
RP-HD-4
(Side Channel)
Turbid,
Warm 8/2/2013 8/16/2013 8/30/2013 9/12/2013 - 9/21/2013
Table 4.11-2. Number of Hester-Dendy multiplate samplers deployed at the four colonization study sites in FA-104 (Whiskers Slough) for the five colonization time
periods.
Site
8-Wk 6-Wk 4-Wk 2-Wk 1-Wk
Shallo
w Deep
Shallo
w Deep
Shallo
w Deep
Shallo
w Deep
Shallo
w Deep
RP-HD-1 3 3 2* 3 3 3 3 3 3 3
RP-HD-2 3 3 3 3 3 3 3 3 3 3
RP-HD-3 3** 3** 3** 3** 3** 3** 3** 3** - -
RP-HD-4 3 3 3** 3** 3 3 3 3 - -
* only 2 replicates for the 6-week shallow sampler set because 1 set of sampler plates had come detached from the cinder block & could not be located
** Sampling set were exposed during their deployment for a short period of time.
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Table 4.11-3. Actual deployment duration for Hester-Dendy multiplate samplers at the four colonization study sites in FA-104 (Whiskers Slough) for the five
colonization time periods.
Site 8-Wk 6-Wk 4-Wk 2-Wk 1-Wk
RP-HD-1 8.1 6 4 2.1 1
RP-HD-2 8.1 6 4 2.1 1
RP-HD-3 7 5 3 1.1 -
RP-HD-4 7.1 5.1 3.1 1.3 -
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Table 5.2-1. Mean chlorophyll-a and Ash Free Dry Mass (AFDM) values (n=5) from composite algae samples collected in 2013 during three index events for sites in the
Middle and Lower River Segments of the Susitna River, and Talkeetna (TKA) River for the River Productivity Study.
Site Macrohabitat Type
Chlorophyll-a (mg/m2) AFDM (g/m2)
Spring Summer Fall Spring Summer Fall
RP-184-1 Tributary Mouth 1.68 0.95 0.61 1.73 0.74 0.62
RP-184-2 Side Channel 0.37 5.76 0.14 1.13 1.30 0.81
RP-184-3 Main Channel 0.74 0.05 0.04 0.52 0.50 0.55
RP-173-1 Tributary Mouth 4.95 9.21 0.20 1.49 4.04 0.42
RP-173-2 Main Channel 0.66 0.06 0.06 0.61 0.30 0.35
RP-173-3 Side Channel 6.86 28.69 41.89 2.87 17.89 12.66
RP-173-4 Side Slough 13.86 14.46 21.14 5.40 13.77 10.18
RP-141-1 Tributary Mouth 0.61 11.22 2.03 0.29 2.17 0.50
RP-141-2 Side Channel 0.82 35.12 1.32 0.91 13.52 2.63
RP-141-3 Multi Split Main Channel 0.32 1.76 0.37 0.39 1.60 0.72
RP-141-4 Upland Slough 5.90 39.02 13.32 4.34 14.16 6.50
RP-104-1 Side Slough 3.77 2.37 46.14 3.92 2.17 11.45
RP-104-2 Side Slough 1.06 16.25 65.73 0.66 11.45 11.46
RP-104-3 Main Channel 0.12 0.20 1.79 0.13 0.46 0.67
RP-104-4 Upland Slough 3.58 3.74 6.02 4.02 5.05 8.98
RP-104-5 Side Channel 0.64 0.28 4.84 0.17 0.31 2.00
RP-81-1 Upland Slough 10.50 1.26 2.46 10.91 13.33 9.80
RP-81-2 Tributary Mouth 3.02 26.36 2.73 1.22 6.45 1.46
RP-81-3 Split Main Channel 0.11 0.04 0.04 0.26 0.28 0.34
RP-81-4 Side Channel 0.27 0.08 0.09 0.51 0.21 0.64
RP-TKA-1 Side Channel 2.90 6.60 0.39 3.54 3.01 0.64
RP-TKA-2 Upland Slough 0.55 5.20 9.41 0.68 6.71 242.64
RP-TKA-3 Side Slough 19.96 24.12 81.26 9.13 8.89 19.18
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10. FIGURES
Figure 3-1. Middle Susitna River Segment, with the four River Productivity sampling stations /Instream Flow Focus Areas selected for the River
Productivity Study, plus the sampling station for reference sites on the Talkeetna River.
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Figure 3-2. Lower Susitna River Segment, with Montana Creek area River Productivity sampling station selected for the River Productivity Study.
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Figure 4.2-1. Focus Area 184 (Watana Dam), and the three River Productivity sampling sites.
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Figure 4.2-2. Focus Area 173 (Stephan Lake Complex), and the four River Productivity sampling sites.
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Figure 4.2-3. Focus Area 141 (Indian River), and the four River Productivity sampling sites.
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Figure 4.2-4. Focus Area 104 (Whiskers Slough), and the five River Productivity sampling sites.
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Figure 4.2-5. Station RP-81 (Montana Creek), and the four River Productivity sampling sites.
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Figure 4.2-6. Talkeetna Station (TKA), and the three River Productivity sampling sites.
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Figure 4.4-1. Sampling equipment used to collect benthic macroinvertebrates in streams and rivers. Top
left: Hess stream sampler. Top right: drift nets. Bottom left: floating aquatic insect emergence trap. Bottom
right: Hester-Dendy multiplate sampler.
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Figure 4.11-1. Hester-Dendy multiplate sampler set retrieved at RP-HD-3 on September 20, 2013. Declining
flows over the previous week resulted in both large amounts of sediment deposited at the site, which was then
dewatered.
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Figure 5.2-1. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals from composite algae
samples collected during three index events in 2013 for sites within FA-184 (Watana Dam) in the Middle
River Segment of the Susitna River.
Figure 5.2-2. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent confidence intervals from
composite algae samples collected during three index events in 2013 for sites within FA-184 (Watana Dam) in
the Middle River Segment of the Susitna River.
RP- 184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean Chlorophyll-a (mg/m2)0
2
4
6
8
10
Spring
Summer
Fall
RP- 184 (Watana Dam)
Station / Site
RP-184-1 RP-184-2 RP-184-3Mean AFDM (g/m2)0.0
0.5
1.0
1.5
2.0
2.5
3.0
Spring
Summer
Fall
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Figure 5.2-3. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals from composite algae
samples collected during three index events in 2013 for sites within FA-173 (Stephan Lake Complex) in the
Middle River Segment of the Susitna River.
Figure 5.2-4. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent confidence intervals from
composite algae samples collected during three index events in 2013 for sites within FA-173 (Stephan Lake
Complex) in the Middle River Segment of the Susitna River.
RP- 173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4Mean Chlorophyll-a (mg/m2)0
5
10
15
20
25
30
35
40
45
50
55
60
SpringSummerFall
RP- 173 (Stephan Lake Complex)
Station / Site
RP-173-1 RP-173-2 RP-173-3 RP-173-4Mean AFDM (g/m2)0
5
10
15
20
25
30
35
40
SpringSummerFall
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FERC Project No. 14241 Page 67 February 2014 Draft
Figure 5.2-5. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals from composite algae
samples collected during three index events in 2013 for sites within FA-141 (Indian River) in the Middle
River Segment of the Susitna River.
Figure 5.2-6. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent confidence intervals from
composite algae samples collected during three index events in 2013 for sites within FA-141 (Indian River) in
the Middle River Segment of the Susitna River.
RP- 141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4Mean Chlorophyll-a (mg/m2)0
5
10
15
20
25
30
35
40
45
50
55
60
SpringSummerFall
RP- 141 (Indian River)
Station / Site
RP-141-1 RP-141-2 RP-141-3 RP-141-4Mean AFDM (g/m2)0
2
4
6
8
10
12
14
16
18
20
22
24
26
SpringSummerFall
INITIAL STUDY REPORT RIVER PRODUCTIVITY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 68 February 2014 Draft
Figure 5.2-7. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals from composite algae
samples collected during three index events in 2013 for sites within FA-104 (Whiskers Slough) in the Middle
River Segment of the Susitna River.
Figure 5.2-8. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent confidence intervals from
composite algae samples collected during three index events in 2013 for sites within FA-104 (Whiskers
Slough) in the Middle River Segment of the Susitna River.
RP- 104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5Mean Chlorophyll-a (mg/m2)0
5
10
15
20
25
45
60
75
90
105
120
SpringSummerFall
RP- 104 (Whiskers Slough)
Station / Site
RP-104-1 RP-104-2 RP-104-3 RP-104-4 RP-104-5Mean AFDM (g/m2)0
2
4
6
8
10
12
14
16
18
SpringSummerFall
INITIAL STUDY REPORT RIVER PRODUCTIVITY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 69 February 2014 Draft
Figure 5.2-9. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals from composite algae
samples collected during three index events in 2013 for sites within RP-81 (Montana Creek) in the Lower
River Segment of the Susitna River.
Figure 5.2-10. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent confidence intervals from
composite algae samples collected during three index events in 2013 for sites within RP-81 (Montana Creek)
in the Lower River Segment of the Susitna River.
RP- 81(Montana Creek)
Station / Site
RP-81-1 RP-81-2 RP-81-3 RP-81-4Mean Chlorophyll-a (mg/m2)0
5
10
15
20
25
30
45
50
SpringSummerFall
RP- 81(Montana Creek)
Station / Site
RP-81-1 RP-81-2 RP-81-3 RP-81-4Mean AFDM (g/m2)0
2
4
6
8
10
12
14
16
18
SpringSummerFall
INITIAL STUDY REPORT RIVER PRODUCTIVITY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 70 February 2014 Draft
Figure 5.2-11. Mean chlorophyll-a values (n=5) with 95 percent confidence intervals from composite algae
samples collected during three index events in 2013 for sites within the Talkeetna River study station.
Figure 5.2-12. Mean Ash Free Dry Mass (AFDM) values (n=5) with 95 percent confidence intervals from
composite algae samples collected during three index events in 2013 for sites within the Talkeetna River study
station.
RP- TKA (Talkeetna River)
Station / Site
RP-TKA-1 RP-TKA-2 RP-TKA-3Mean Chlorophyll-a (mg/m2)0
5
10
15
20
25
30
35
40
80
100
120
140
160
SpringSummerFall
RP- TKA (Talkeetna River)
Station / Site
RP-TKA-1 RP-TKA-2 RP-TKA-3Mean AFDM (g/m2)0
5
10
15
20
100
200
300
400 SpringSummerFall
INITIAL STUDY REPORT RIVER PRODUCTIVITY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 February 2014 Draft
APPENDIX A: REVIEW OF THE EFFECTS OF HYDROPOWER ON
FACTORS CONTROLLING BENTHIC COMMUNITIES
[See separate file for Appendix]
INITIAL STUDY REPORT RIVER PRODUCTIVITY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 February 2014 Draft
APPENDIX B: SITE-SPECIFIC SAMPLE COLLECTION LOCATIONS
[See separate file for Appendix]
INITIAL STUDY REPORT RIVER PRODUCTIVITY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 February 2014 Draft
APPENDIX C: ANALYSIS OF POTENTIALLY DEWATERED RIVER
PRODUCTIVITY SAMPLING SITES IN 2013
[See separate file for Appendix.]
INITIAL STUDY REPORT RIVER PRODUCTIVITY STUDY (9.8)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 February 2014 Draft
APPENDIX D: TALKEETNA SITE SELECTION CONSULTATION
DOCUMENTATION
[See separate file for Appendix.]