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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
2012 instream flow planning study, Summary review of Susitna River
aquatic and instream flow studies conducted in the 1980s with relevance to
proposed Susitna-Watana Dam Project - 2012 : a compendium of technical
memoranda
SuWa 69
Author(s) – Personal:
Author(s) – Corporate:
Prepared by R2 Resource Consultants, Inc.
AEA-identified category, if specified:
2012 Environmental Studies
AEA-identified series, if specified:
Series (ARLIS-assigned report number):
Susitna-Watana Hydroelectric Project document number 69
Existing numbers on document:
Published by:
[Anchorage, Alaska : Alaska Energy Authority, 2013]
Date published:
March 19, 2013
Published for:
Prepared for Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Final or Draft status, as indicated:
Document type:
Technical Memorandum
Pagination:
326, [11] p.
Related work(s):
Appendix 3 (SuWa 69 app. 3)
Pages added/changed by ARLIS:
Notes:
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
2012 Instream Flow Planning Study
Summary Review of Susitna River Aquatic and
Instream Flow Studies Conducted in the 1980s with
Relevance to Proposed Susitna – Watana Dam Project
– 2012: A Compendium of Technical Memoranda
Prepared for
Alaska Energy Authority
Prepared by
R2 Resource Consultants, Inc.
March 19, 2013
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i March 2013
TABLE OF CONTENTS
1. Introduction ........................................................................................................................1
2. Brief History of the 1980s Susitna Project .......................................................................4
3. Technical Memorandum – River Stratification and Study Site Selection Process:
1980s Studies and 2013-2014 Studies ...............................................................................6
3.1. Su-Hydro 1980s Studies – River Stratification, Classification and Site
Selection .............................................................................................................6
3.1.1. Middle River Stratification ............................................................. 6
3.1.2. Lower River Stratification and Classification ................................. 8
3.1.3. Study and Sample Sites ................................................................. 10
3.2. Susitna-Watana Hydroelectric Project 2013-2014 Studies: Stratification and
Study Site Selection .........................................................................................13
3.2.1. River Stratification and Classification .......................................... 13
3.3. Selection of Study Areas/Study Sites ..............................................................15
3.3.1. Representative Sites ...................................................................... 15
3.3.2. Critical Sites .................................................................................. 15
3.3.3. Randomly Located Sites ............................................................... 16
3.3.4. Focus Areas and Study Sites – Middle River Segment ................ 16
3.3.5. Study Sites – Lower River Segment ............................................. 17
4. Technical Memorandum – Summary of Fish Distribution and Abundance Studies
Conducted During the 1980s Su-Hydro Project ...........................................................18
4.1. Summary of Methods Used .............................................................................18
4.2. Study Site Locations ........................................................................................19
4.2.1. Upper River Study Sites................................................................ 20
4.2.2. Middle River Study Sites .............................................................. 20
4.2.3. Lower River Study Sites ............................................................... 21
4.3. Results ..............................................................................................................22
4.3.1. Upper River Studies ...................................................................... 22
4.3.2. Middle River Studies .................................................................... 25
5. Technical Memorandum – Selection of Target Species and Development of Species
Periodicity Information for the Susitna River ..............................................................44
5.1. Su-Hydro 1980s Studies ..................................................................................44
5.1.1. Target Species Selection ............................................................... 44
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5.1.2. Species Periodicities ..................................................................... 45
5.2. Susitna-Watana 2013-2014 Studies .................................................................73
6. Technical Memorandum – Habitat Suitability Curve Development Studies for the
Susitna River ....................................................................................................................75
6.1. Su-Hydro 1980s Studies ..................................................................................75
6.1.1. Methods......................................................................................... 76
6.1.2. Results ........................................................................................... 83
6.2. Other Relevant HSC Curve Sets ......................................................................96
6.2.1. Study Descriptions ........................................................................ 97
6.2.2. HSC Data Set Comparisons .......................................................... 98
6.3. Susitna-Watana HSC Studies .........................................................................100
6.3.1. 2012 HSC Studies ....................................................................... 100
6.3.2. Proposed 2013-2014 Studies....................................................... 109
7. Technical Memorandum – Review of Habitat Modeling Methods Applicable for the
susitna River ...................................................................................................................110
7.1. Su-Hydro 1980s Studies ................................................................................110
7.1.1. PHABSIM Models ...................................................................... 111
7.1.2. Direct Input Habitat (DIHAB) Model......................................... 112
7.1.3. Resident Juvenile Habitat (RJHAB) Model ................................ 113
7.1.4. Habitat Mapping ......................................................................... 114
7.1.5. Aerial Photography Interpretation – Habitat Surface Area Mapping
..................................................................................................... 114
7.1.6. Extrapolation Analyses ............................................................... 115
7.2. Susitna-Watana 2013-2014 Studies ...............................................................117
7.2.1. Target Range of Flows ................................................................ 117
7.2.2. Habitat Model Selection ............................................................. 118
7.2.3. Temporal and Spatial Habitat Analyses ...................................... 126
7.2.4. Instream Flow Study Integration ................................................ 131
8. Technical Memorandum – Biologically Relevant Physical Processes in the Susitna
River ................................................................................................................................135
8.1. Su-Hydro 1980s Studies ................................................................................135
8.1.1. Groundwater Upwelling.............................................................. 135
8.1.2. Turbid and Clear Water Zones .................................................... 138
8.1.3. Ice Processes and Open Water Leads ......................................... 139
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii March 2013
8.1.4. Substrate Composition ................................................................ 141
8.2. Susitna-Watana 2013-2014 Studies ...............................................................142
9. References .......................................................................................................................143
10. Tables ..............................................................................................................................157
11. Figures .............................................................................................................................211
LIST OF TABLES
Table 2.1-1. Types of instream flow and fish related studies conducted as part of the Su-Hydro
Fish and Aquatics Study Program during 1981 to 1986. .................................................... 158
Table 3.1-1. Designated Fish Habitat Sites surveyed June through September 1982. .............. 160
Table 3.1-2. Description of habitat zones sampled at Designated Fish Habitat Sites: June through
September 1982 (From Estes and Schmidt 1983). .............................................................. 160
Table 3.1-3. Aggregate Hydraulic (H), Water Source (W) and Velocit y (V) zones. ................ 161
Table 3.1-4. JAHS sample sites for the AJ and AH components of the Aquatic Studies Program
during 1983 and 1984. ........................................................................................................ 162
Table 3.3-1. Locations, descriptions and selection rationale of final Focus Areas for detailed
study in the Middle River Segment of the Susitna River. Focus Area identification numbers
(e.g., Focus Area 184) represent the truncated Project River Mile (PRM) at the downstream
end of each Focus Area. ...................................................................................................... 164
Table 4.1-1. Deployment of fishwheel (F) and sonar stations (S) from 1981 to 1985. ............. 165
Table 4.1-2. Number of fish radio-tagged by year in the Middle Susitna River (MR) and Lower
Susitna River (LR). ............................................................................................................. 166
Table 4.1-3. Deployment of incline plane traps from 1982 to 1985. Stations with two traps had
one each river bank. S=Stationary, M=Mobile. ................................................................. 167
Table 4.2-1. Sites sampled in the Middle Susitna River 1981 to 1985. ..................................... 168
Table 4.2-2. Sites sampled in the Lower Susitna River 1981 to 1984. ...................................... 170
Table 4.3-1. Fish community in the Susitna River drainage. ..................................................... 172
Table 4.3-2. Information from Buckwalter (2011) Synopsis of ADF&G’s Upper Susitna
Drainage Fish Inventory, August 2011. .............................................................................. 173
Table 4.3-3. Estimated Arctic grayling population sizes in tributaries to the upper Middle and
Upper Susitna River during 1981 and 1982. ....................................................................... 174
Table 4.3-4. Chinook salmon escapement survey results from 1982 to 1985 upstream of RM
152. Surveys conducted by helicopter. .............................................................................. 175
Table 5.1-1. Periodicity of Chinook salmon utilization among macro-habitat types in the Middle
(RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna River by life history
REPORT 2012 INSTREAM FLOW PLANNING STUDY
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FERC Project No. 14241 Page iv March 2013
stage. In the Upper Segment (RM 260 – RM 184), adult Chinook are believed to exhibit
similar habitat use to that shown for the Middle Segment, while juvenile Chinook rearing
and migration timing in this segment is not known. Shaded areas indicate timing of
utilization by macro-habitat type and dark gray areas represent areas and timing of peak use.
............................................................................................................................................. 176
Table 5.1-2. Periodicity of sockeye salmon utilization among macro-habitat types in the Middle
(RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna River by life history
stage. Shaded areas indicate timing of utilization by macro-habitat type and dark gray areas
represent areas and timing of peak use. .............................................................................. 177
Table 5.1-3. Periodicity of chum salmon utilization among macro-habitat types in the Middle
(RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna River by life history
stage. Shaded areas indicate timing of utilization by macro-habitat type and dark gray areas
represent areas and timing of peak use. .............................................................................. 178
Table 5.1-4. Periodicity of coho salmon utilization among macro-habitat types in the Middle
(RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna River by life history
stage. Shaded areas indicate timing of utilization by macro-habitat type and dark gray areas
represent areas and timing of peak use. .............................................................................. 179
Table 5.1-5. Periodicity of pink salmon utilization among macro-habitat types in the Middle
(RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna River by life history
stage. Shaded areas indicate timing of utilization by macro-habitat type and dark gray areas
represent areas and timing of peak use. .............................................................................. 180
Table 5.1-6. Periodicity of rainbow trout utilization among macro-habitat types in the Susitna
River by life history stage. Shaded areas indicate timing of utilization by macro-habitat
type and dark gray areas represent areas and timing of peak use. ...................................... 181
Table 5.1-7. Periodicity of Arctic grayling utilization among macro-habitat types in the Susitna
River by life history stage. Shaded areas indicate timing of utilization by macro-habitat
type and dark gray areas represent areas and timing of peak use. ...................................... 182
Table 5.1-8. Periodicity of burbot utilization among macro-habitat types in the Susitna River by
life history stage. Shaded areas indicate timing of utilization by macro-habitat type and
dark gray areas represent areas and timing of peak use. ..................................................... 183
Table 5.1-9 Periodicity of round whitefish utilization among macro-habitat types in the Susitna
River by life history stage. Shaded areas indicate timing of utilization by macro-habitat
type and dark gray areas represent areas and timing of peak use. ...................................... 184
Table 5.1-10. Periodicity of humpback whitefish utilization among macro-habitat types in the
Susitna River by life history stage. Shaded areas indicate timing of utilization by macro-
habitat type and dark gray areas represent areas and timing of peak use. .......................... 185
Table 5.1-11 Periodicity of longnose sucker in the Susitna River by life history stage and habitat
type. Shaded areas represent utilization of habitat types and temporal periods and dark gray
areas indicate peak use. ....................................................................................................... 186
Table 5.1-12. Periodicity of Dolly Varden in the Susitna River by life history stage and habitat
type. Shaded areas represent utilization of habitat types and temporal periods and dark gray
areas indicate peak use. ....................................................................................................... 187
REPORT 2012 INSTREAM FLOW PLANNING STUDY
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FERC Project No. 14241 Page v March 2013
Table 5.1-13. Periodicity of Bering cisco utilization among macro-habitat types in the Susitna
River by life history stage. Shaded areas indicate timing of utilization by macro-habitat
type and dark gray areas represent areas and timing of peak use. ...................................... 188
Table 5.1-14. Periodicity of eulachon utilization among macro-habitat types in the Susitna River
by life history stage. Shaded areas indicate timing of utilization by macro-habitat type and
dark gray areas represent areas and timing of peak use. ..................................................... 189
Table 6.1-1. Species, lifestages, and habitat parameters for which HSC curves have been
developed for the Middle (M) and Lower (L) Susitna River. ............................................. 190
Table 6.1-2. Substrate codes used in the development of HSC curves for the Susitna River
during studies in the 1980s (Vincent-Lang et al. 1984a, 1984b) and for three Bristol Bay
drainages (North/South Fork Koktuli Rivers and Upper Talarik Creek; PLP 2011). ......... 191
Table 6.1-3. Number of salmon redds observed in spawning HSC data collection efforts in the
Middle Segment Susitna River during 1982-1983 studies. ................................................ 192
Table 6.1-4. Sampling effort (number of cells sampled) and juvenile salmon catch (all age
classes) by gear type in the Middle Susitna River during 1981-1982 studies (Suchanek et al.
1984b) ................................................................................................................................. 192
Table 6.1-5. Cover type and percent cover habitat suitability criteria for juvenile salmon in the
Middle Susitna River (Suchanek et al. 1984b). .................................................................. 193
Table 6.1-6. Cover type and percent cover habitat suitability criteria for juvenile salmon in the
Lower Susitna River (Suchanek et al. 1985). ..................................................................... 194
Table 6.1-7. Adult resident fish catch by gear type in the Middle Segment Susitna River during
1981-1982 studies (Suchanek et al. 1984b). Sampling effort involved boat electrofishing in
176 cells and hook-and-line sampling in 79 cells. .............................................................. 195
Table 6.1-8. Cover type habitat suitability criteria for resident fish in the Middle Susitna River
(Suchanek et al. 1984b). ...................................................................................................... 195
Table 6.3-1. Summary of the proposed target species and life stages, macro-habitat types,
sample sites, potential sampling techniques, and sampling timing applied during 2012 HSC
curve validation surveys. .................................................................................................... 196
Table 6.3-2. Site-specific habitat suitability measurements recorded during 2012 at Middle and
Lower Susitna River sampling sites, by fish life stage. ...................................................... 197
Table 6.3-3. Proposed substrate classification system for use in development of HSC/HSI curves
for the Susitna-Watana Project (adapted from Wentworth 1922)....................................... 198
Table 6.3-4. Number of spawning redds sampled by river reach and macrohabitat type during
HSC surveys of the Susitna River, Alaska (combined R2 and LGL datasets). .................. 198
Table 6.3-5. Number of HSC made within each of the major macrohabitat types for each target
species and life stage during the 2012 HSC surveys of the Susitna River, Alaska. ........... 199
Table 6.3-6. Number of HSC observations made within each of the major macrohabitat types for
each target species and life stage during the 2012 HSC surveys of the Susitna River, Alaska.
............................................................................................................................................. 200
REPORT 2012 INSTREAM FLOW PLANNING STUDY
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Table 6.3-7. Periodicity of Pacific salmon habitat utilization in the Middle Segment (RM
184-98.5) of the Susitna River by species and life history stage. Shaded areas indicate
timing of utilization and dark gray areas represent peak use. ............................................. 201
Table 7.1-1. Instream flow sites and habitat modeling methods used during the 1980s in the
Middle and Lower Susitna River (Marshall et al. 1984; Sandone et al. 1984; Vincent-Lang
et al. 1984b; Hilliard et al. 1985; Suchanek et al. 1985). .................................................... 203
Table 7.1-2. Representative Groups used as part of the methodology to extrapolate results from
modeled to non-modeled areas in the Middle Susitna River during 1980s studies. Source:
Aaserude et al. (1985). ........................................................................................................ 204
Table 7.1-3. Representative Groups used as part of the methodology to extrapolate results from
modeled to non-modeled areas in the Middle Susitna River during 1980s studies. Source:
Aaserude et al. (1985). ........................................................................................................ 205
Table 7.2-1. Assessment of physical and biological processes and potential habitat modeling
techniques. .......................................................................................................................... 206
Table 7.2-2. Conceptual Comparison of Multiple Resource Indicators of the Effects of
Alternative Operational Scenarios for the Susitna-Watana Hydroelectric Project. Indicators
to be coordinated with resource-specific working groups. ................................................. 207
Table 8.1-1. Description of habitat zones sampled at Designated Fish Habitat Sites: June through
September 1982 (From Estes and Schmidt 1983). .............................................................. 209
Table 8.1-2. Aggregate Hydraulic (H), Water Source (W) and Velocit y (V) zones. Source: Estes
and Schmidt (1983), Schmidt et al. (1983). ........................................................................ 210
LIST OF FIGURES
Figure 3.1-1. Habitat types identified in the middle reach of the Susitna River during the 1980s
studies (adapted from ADF&G 1983b; Trihey 1982). ........................................................ 212
Figure 3.1-2. Map of Designated Fish Habitat (DFH) sites sampled on the Susitna River, June
through September 1982. .................................................................................................... 213
Figure 3.1-3. Hypothetical slough with delineated habitat zones. ............................................. 214
Figure 3.1-4. Typical arrangement of transects, grids, and cells at a JAHS site. ...................... 215
Figure 3.2-1. Map depicting the Upper, Middle and Lower Segments of the Susitna River
potentially influenced by the Susitna-Watana Hydroelectric Project. ................................ 216
Figure 3.3-1. Map of the Middle Segment of the Susitna River depicting the eight Geomorphic
Reaches and locations of proposed Focus Areas. No Focus Areas are proposed for in MR-3
and MR-4 due to safety issues related to sampling within or proximal to Devils Canyon. 217
Figure 3.3-2. Map showing Focus Area 184 that begins at Project River Mile 184.7 and extends
upstream to PRM 185.7. The Focus Area is located about 1.4 miles downstream of the
proposed Watana Dam site near Tsusena Creek. ................................................................ 218
REPORT 2012 INSTREAM FLOW PLANNING STUDY
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FERC Project No. 14241 Page vii March 2013
Figure 3.3-3. Map showing Focus Area 173 beginning at Project River Mile 173.6 and extends
upstream to PRM 175.4. This Focus Area is near Stephan Lake and consists of main
channel and a side channel complex. .................................................................................. 219
Figure 3.3-4. Map showing Focus Area 171 beginning at Project River Mile 171.6 and extends
upstream to PRM 173. This Focus Area is near Stephan Lake and consists of main channel
and a single side channel with vegetated island. ................................................................. 220
Figure 3.3-5. Map showing Focus Area 151 beginning at Project River Mile 151.8 and extends
upstream to PRM 152.3. This single main channel Focus Area is at the Portage Creek
confluence. .......................................................................................................................... 221
Figure 3.3-6. Map showing Focus Area 144 beginning at Project River Mile 144.4 and extends
upstream to PRM 145.7. This Focus Area is located about 2.3 miles upstream of Indian
River and includes Side Channel 21 and Slough 21. .......................................................... 222
Figure 3.3-7. Map showing Focus Area 141 beginning at Project River Mile 141.8 and extends
upstream to PRM 143.4. This Focus Area includes the Indian River confluence and a range
of main channel and off-channel habitats. .......................................................................... 223
Figure 3.3-8. Map showing Focus Area 138 beginning at Project River Mile 138.7 and extends
upstream to PRM 140. This Focus Area is near Gold Creek and consists of a complex of
side channel, side slough and upland slough habitats including Upper Side Channel 11 and
Slough 11. ........................................................................................................................... 224
Figure 3.3-9. Map showing Focus Area 128 beginning at Project River Mile 128.1 and extends
upstream to PRM 129.7. This Focus Area consists of side channel, side slough and
tributary confluence habitat features including Skull Creek. .............................................. 225
Figure 3.3-10. Map showing Focus Area 115 beginning at Project River Mile 115.3 and extends
upstream to PRM 116.5. This Focus Area is located about 0.6 miles downstream of Lane
Creek and consists of side channel and upland slough habitats including Slough 6A. ...... 226
Figure 3.3-11. Map showing Focus Area 104 beginning at Project River Mile 104.8 and extends
upstream to PRM 106. This Focus Area covers the diverse range of habitats in the
Whiskers Slough complex. ................................................................................................. 227
Figure 3.3-12. Map showing proposed location of lower Susitna River instream flow-fish habitat
transects in Geomorphic Reach LR-1 in the vicinity of Trapper Creek. The proposed
location, number, angle, and transect endpoints are tentative pending on-site confirmation
during open-water conditions. Where feasible, instream flow fish habitat transects will be
co-located with geomorphology, open-water flow routing, and instream flow-riparian
transects. .............................................................................................................................. 228
Figure 3.3-13. Map showing proposed location of lower Susitna River instream flow-fish habitat
transects in Geomorphic Reach LR-2 in the vicinity of Caswell Creek. The proposed
location, number, angle, and transect endpoints are tentative pending on-site confirmation
during open-water conditions. Where feasible, instream flow fish habitat transects will be
co-located with geomorphology, open-water flow routing and instream flow-riparian
transects. .............................................................................................................................. 229
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page viii March 2013
Figure 3.3-14. Map of the Lower Segment of the Susitna River depicting the six Geomorphic
Reaches and locations of proposed 2013 study areas for geomorphology, instream flow–
fish, instream flow-riparian and fish distribution and abundance. ...................................... 230
Figure 4.2-1. Sampling effort at 225 mainstem Selected Fish Habitat sites during 1982. ........ 231
Figure 4.3-1. Distribution of Chinook salmon in the Susitna River Basin from ADF&G’s
Anadromous Waters Catalog. ............................................................................................. 232
Figure 4.3-2. Catch per unit effort of Artic grayling by hook and line in tributaries to the upper
Middle and Upper Susitna River during 1981 and 1982. ................................................... 233
Figure 4.3-3. Total catch of burbot by trotlines during 1981 (top) at tributary mouths and CPUE
of burbot at mainstem sites in the Upper Susitna River during 1982 (bottom). ................. 234
Figure 4.3-4. Spawning habitat utilization by anadromous salmon species and average run size
in the middle Susitna River. ................................................................................................ 235
Figure 4.3-5. Distribution of Chinook salmon spawning in the Middle River 1982 to 1985. ... 236
Figure 4.3-6. Distribution of Chinook Salmon spawning in the Susitna River 1976 to 1984. .. 236
Figure 4.3-7. Escapement to Sunshine, Talkeetna, and Curry stations based upon mark-recapture
techniques. .......................................................................................................................... 237
Figure 4.3-8. Chinook salmon (age 0+) daily catch per unit effort and cumulative catch recorded
at the mouth of Indian River. .............................................................................................. 237
Figure 4.3-9. Chinook salmon (age 0+) daily catch per unit effort and cumulative catch recorded
at the Talkeetna (upper figure) and Flathorn (lower figure) stationary outmigrant traps,
1985. .................................................................................................................................... 238
Figure 4.3-10. Chinook salmon (age 1+) daily catch per unit effort and cumulative catch
recorded at the Talkeetna (upper figure) and Flathorn (lower figure) stationary outmigrant
traps, 1985. .......................................................................................................................... 239
Figure 4.3-11. Second run sockeye salmon escapement estimates to the Susitna River 1981 to
1985. .................................................................................................................................... 240
Figure 4.3-12. Distribution of sockeye salmon in the Susitna River Basin from ADF&G’s
Anadromous Waters Catalog. ............................................................................................. 241
Figure 4.3-13. Distribution of sockeye spawning in Middle Susitna River sloughs. ................ 242
Figure 4.3-14. Chum salmon escapement estimates to the Susitna River 1981 to 1985. .......... 242
Figure 4.3-15. Distribution of chum salmon in the Susitna River Basin from ADF&G’s
Anadromous Waters Catalog. ............................................................................................. 243
Figure 4.3-16. Spawning distribution of 210 chum salmon radio-tagged at Flathorn during 2009.
............................................................................................................................................. 244
Figure 4.3-17. Chum salmon spawning distribution among tributaries and sloughs in the Middle
Susitna River based upon peak counts. ............................................................................... 244
REPORT 2012 INSTREAM FLOW PLANNING STUDY
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Figure 4.3-18. Density distribution and juvenile chum salmon by macrohabitat type on the
Susitna River between the Chulitna River confluence and Devils Canyon, May through
November 1983. .................................................................................................................. 245
Figure 4.3-19. Seasonal distribution and relative abundance of juvenile chum salmon on the
Susitna River between the Chulitna River confluence and Devils Canyon, May through
November 1983. .................................................................................................................. 246
Figure 4.3-20. Coho salmon escapement estimates to the Susitna River 1981 to 1985. ........... 247
Figure 4.3-21. Distribution of coho salmon in the Susitna River Basin from ADF&G’s
Anadromous Waters Catalog. ............................................................................................. 248
Figure 4.3-22. Spawning distribution of 275 coho salmon radio-tagged at Flathorn during 2009.
............................................................................................................................................. 249
Figure 4.3-23. Density distribution and juvenile coho salmon by macrohabitat type on the
Susitna River between the Chulitna River confluence and Devils Canyon, May through
November 1983. .................................................................................................................. 249
Figure 4.3-24. Seasonal distribution and relative abundance of juvenile coho salmon on the
Susitna River between the Chulitna River confluence and Devils Canyon, May through
November 1983. .................................................................................................................. 250
Figure 4.3-25. Pink salmon escapement estimates to the Susitna River 1981 to 1985. ............ 251
Figure 4.3-26. Distribution of pink salmon in the Susitna River Basin from ADF&G’s
Anadromous Waters Catalog. ............................................................................................. 252
Figure 4.3-27. Pink salmon spawning distribution among tributaries in the Middle Susitna River
based upon peak counts. ..................................................................................................... 253
Figure 4.3-28. Total catch of rainbow trout at DFH sites within the middle and lower Susitna
River segments during 1982. .............................................................................................. 254
Figure 4.3-29. Total catch of Artic grayling at DFH sites in the Lower and Middle Susitna River
during 1982. ........................................................................................................................ 255
Figure 4.3-30. Total catch of Dolly Varden at DFH sites during 1982 by gear type. ............... 256
Figure 4.3-31. CPUE of burbot at DFH sites during 1982. ....................................................... 257
Figure 4.3-32. Total catch of round whitefish at DFH sites during 1982 by gear type. ............ 258
Figure 4.3-33. Total catch of humpback whitefish at DFH sites during 1982 by gear type. ..... 259
Figure 4.3-34. Total catch of longnose sucker at DFH sites during 1982 by gear type. ........... 260
Figure 4.3-35. Total catch of threespine stickleback at DFH sites during 1982 by gear type. .. 261
Figure 4.3-36. Total catch of slimy sculpin at DFH sites during 1982 by gear type. ................ 262
Figure 4.3-37. Deshka River Chinook salmon escapement. ...................................................... 263
Figure 4.3-38. Escapement of Chinook salmon to Susitna River index streams other than the
Deshka River. ...................................................................................................................... 263
REPORT 2012 INSTREAM FLOW PLANNING STUDY
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Figure 4.3-39. Mean catch rate of juvenile Chinook salmon at JAHS sites by turbidity bin in the
Lower Susitna River, 1984. ................................................................................................ 264
Figure 4.3-40. Location of fish wheel capture sites, weirs, and radio-tracking stations in the
Susitna River drainage, and the terminal distribution of radio-tagged sockeye salmon based
on aerial surveys, 2007 (top) and 2008 (bottom). ............................................................... 265
Figure 4.3-41. Average chum fry catch rates at side channels in the lower river by turbidity bin
during June through mid-July 1984. ................................................................................... 266
Figure 4.3-42. Seasonal distribution and relative abundance of juvenile coho salmon on the
Lower Susitna River during the open water period, 1984. ................................................. 267
Figure 4.3-43. Pink salmon escapement estimates to the Deshka River 1996 to 2012. ............ 268
Figure 5.1-1. Relative abundance of juvenile Pacific salmon species in the Middle Segment of
the Susitna River among macro-habitat types during the open water season. Sources:
Trihey and Associates and Entrix (1985) and Dugan et al. (1984). .................................... 269
Figure 6.1-1. Depth HSC developed during the 1980s for chum salmon spawning in the Middle
Susitna River (Vincent-Lang et al. 1984b), the Terror and Kizhuyak Rivers (Baldrige
1981), and Wilson River/Tunnel Creek (Lyons and Nadeau 1985). .................................. 270
Figure 6.1-2. Velocity HSC developed during the 1980s for chum salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984b), the Terror and Kizhuyak Rivers
(Baldrige 1981), and Wilson River/Tunnel Creek (Lyons and Nadeau 1985). .................. 270
Figure 6.1-3. Substrate HSC developed during the 1980s for chum salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984b). ............................................................ 271
Figure 6.1-4. Combined substrate/upwelling HSC developed during the 1980s for chum salmon
spawning in the Middle Susitna River (Vincent-Lang et al. 1984b). Codes ending in “.0”
indicate upwelling absent and codes ending in “.1” indicate upwelling present. ............... 271
Figure 6.1-5. Depth HSC developed during the 1980s for juvenile chum salmon in the Lower
(Suchanek et al. 1985) and Middle (Suchanek et al. 1984a) Susitna River. ....................... 272
Figure 6.1-6. Velocity HSC developed during the 1980s for juvenile chum salmon in the Lower
(Suchanek et al. 1985) and Middle (Suchanek et al. 1984a) Susitna River. Note that the two
curves are identical based on verification efforts in the Lower River. ............................... 272
Figure 6.1-7. Depth HSC developed during the 1980s for sockeye salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984b), and from combined observations in the
North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011). ..... 273
Figure 6.1-8. Velocity HSC developed during the 1980s for sockeye salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984b), and from combined observations in the
North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011) ...... 273
Figure 6.1-9. Substrate HSC developed during the 1980s for sockeye salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984b), and from combined observations in the
North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011). ..... 274
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Figure 6.1-10. Combined substrate/upswelling HSC developed during the 1980s for sockeye
salmon spawning in the Middle Susitna River (Vincent-Lang et al. 1984b). Codes ending in
“.0” indicate upwelling absent and codes ending in “.1” indicate upwelling present......... 274
Figure 6.1-11. Depth HSC developed during the 1980s for juvenile sockeye salmon in the
Lower (Suchanek et al. 1985) and Middle (Suchanek et al. 1984a) Susitna River, and from
combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper
Talarik Creek (PLP 2011). .................................................................................................. 275
Figure 6.1-12. Velocity HSC developed during the 1980s for juvenile sockeye salmon in the
Lower (Suchanek et al. 1985) and Middle (Suchanek et al. 1984a) Susitna River, and from
combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper
Talarik Creek (PLP 2011). .................................................................................................. 275
Figure 6.1-13. Depth HSC developed during the 1980s for Chinook salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984a), from combined observations in the North
(NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011), and for
Wilson River/Tunnel Creek (Lyons and Nadeau 1985). .................................................... 276
Figure 6.1-14. Velocity HSC developed during the 1980s for Chinook salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984a), from combined observations in the North
(NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011), and for
Wilson River/Tunnel Creek (Lyons and Nadeau 1985). .................................................... 276
Figure 6.1-15. Substrate HSC developed during the 1980s for Chinook salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984a), and from combined observations in the
North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011). ..... 277
Figure 6.1-16. Depth HSC developed during the 1980s for juvenile Chinook salmon in the
Lower (Suchanek et al. 1985) and Middle (Suchanek et al. 1984a) Susitna River, from
combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper
Talarik Creek (PLP 2011), for Wilson River/Tunnel Creek (Lyons and Nadeau 1985), and
for the Kenai River (Estes and Kuntz 1986). ...................................................................... 277
Figure 6.1-17. Velocity HSC developed during the 1980s for juvenile Chinook salmon in the
Lower (Suchanek et al. 1985) and Middle (Suchanek et al. 1984a) Susitna River, from
combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper
Talarik Creek (PLP 2011), for Wilson River/Tunnel Creek (Lyons and Nadeau 1985), and
for the Kenai River (Estes and Kuntz 1986). ...................................................................... 278
Figure 6.1-18. Depth HSC developed during the 1980s for coho salmon spawning in the Middle
Susitna River (Vincent-Lang et al. 1984a), from combined observations in the North (NFK)
and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011), for the Terror and
Kizhuyak Rivers (Baldrige 1981), and for Wilson River/Tunnel Creek (Lyons and Nadeau
1985). .................................................................................................................................. 278
Figure 6.1-19. Velocity HSC developed during the 1980s for coho salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984a, from combined observations in the North
(NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011), for the Terror
and Kizhuyak Rivers (Baldrige 1981), and for Wilson River/Tunnel Creek (Lyons and
Nadeau 1985). ..................................................................................................................... 279
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Figure 6.1-20. Substrate HSC developed during the 1980s for coho salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984a), and from combined observations in the
North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011). ..... 279
Figure 6.1-21. Depth HSC developed during the 1980s for juvenile coho salmon in the Lower
(Suchanek et al. 1985) and Middle (Suchanek et al. 1984a) Susitna River, from combined
observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek
(PLP 2011), for the Terror and Kizhuyak Rivers (Baldrige 1981), and for Wilson
River/Tunnel Creek (Lyons and Nadeau 1985). Note that the Middle and Lower Susitna
River curves are identical based on verification efforts in the Lower River. ..................... 280
Figure 6.1-22. Velocity HSC developed during the 1980s for juvenile coho salmon in the Lower
(Suchanek et al. 1985) and Middle (Suchanek et al. 1984a) Susitna River, from combined
observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik Creek
(PLP 2011), for the Terror and Kizhuyak Rivers (Baldrige 1981), and for Wilson
River/Tunnel Creek (Lyons and Nadeau 1985). Note that the Middle and Lower Susitna
River curves are identical based on verification efforts in the Lower River. ..................... 280
Figure 6.1-23. Depth HSC developed during the 1980s for pink salmon spawning in the Middle
Susitna River (Suchanek et al. 1984a), the Terror and Kizhuyak Rivers (Baldrige 1981), and
Wilson River/Tunnel Creek (Lyons and Nadeau 1985). .................................................... 281
Figure 6.1-24. Velocity HSC developed during the 1980s for pink salmon spawning in the
Middle Susitna River (Suchanek et al. 1984a), the Terror and Kizhuyak Rivers (Baldrige
1981), and Wilson River/Tunnel Creek (Lyons and Nadeau 1985). .................................. 281
Figure 6.1-25. Substrate HSC developed during the 1980s for pink salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984a). ............................................................ 282
Figure 6.1-26. Depth HSC developed during the 1980s for rainbow trout adult in the Middle
Susitna River (Suchanek et al. 1984b). ............................................................................... 282
Figure 6.1-27. Velocity HSC developed during the 1980s for rainbow trout adult in the Middle
Susitna River (Suchanek et al. 1984b). ............................................................................... 283
Figure 6.1-28. Depth HSC developed during the 1980s for adult arctic grayling in the Middle
Susitna River (Suchanek et al. 1984b), and from combined observations in the North (NFK)
and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011). ........................... 283
Figure 6.1-29. Velocity HSC developed during the 1980s for adult arctic grayling in the Middle
Susitna River (Suchanek et al. 1984b), and from combined observations in the North (NFK)
and South (SFK) Koktuli Rivers and Upper Talarik Creek (PLP 2011). ........................... 284
Figure 6.1-30. Depth HSC developed during the 1980s for adult round whitefish in the Middle
Susitna River (Suchanek et al. 1984b) ................................................................................ 284
Figure 6.1-31. Velocity HSC developed during the 1980s for adult round whitefish in the
Middle Susitna River (Suchanek et al. 1984b) ................................................................... 285
Figure 6.1-32. Depth HSC developed during the 1980s for juvenile round whitefish in the
Middle Susitna River (Suchanek et al. 1984b). .................................................................. 285
Figure 6.1-33. Velocity HSC developed during the 1980s for juvenile round whitefish in the
Middle Susitna River (Suchanek et al. 1984b). .................................................................. 286
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Figure 6.1-34. Depth HSC developed during the 1980s for adult longnose sucker in the Middle
Susitna River (Suchanek et al. 1984b). ............................................................................... 286
Figure 6.1-35. Velocity HSC developed during the 1980s for adult longnose sucker in the
Middle Susitna River (Suchanek et al. 1984b). .................................................................. 287
Figure 6.3-1. Daily discharge values from the USGS gage at Gold Creek (#15292000) on the
Susitna River, from 17 July to 19 September 2012. ........................................................... 287
Figure 6.3-2. Water temperature values from the mainstem Susitna River upstream of Whiskers
Creek from July through October 2012. ............................................................................. 288
Figure 6.3-3. Example of a typical redd observed during spawning surveys. Depth, velocity,
substrate, and redd dimensions were measured at each redd. ............................................. 288
Figure 6.3-4. Example photos of methods used to evaluate visibility conditions using a secchi
disk prior to conducting microhabitat snorkel surveys. ...................................................... 289
Figure 6.3-5. Utilizing snorkel surveys to identify fish habitat use of tributaries delta areas of the
Susitna River, Alaska. ......................................................................................................... 290
Figure 6.3-6. Utilizing stick/pole seine surveys to identify fish habitat use in turbid water areas
of Susitna River, Alaska. .................................................................................................... 291
Figure 6.3-7. Adult arctic grayling captured during seining surveys of turbid water areas
downstream of the proposed Watana Dam site. .................................................................. 292
Figure 6.3-8. Map depicting the Upper, Middle and Lower Segments of the Susitna River
potentially influenced by the Susitna-Watana Hydroelectric Project and 2012 HSC sampling
locations. ............................................................................................................................. 293
Figure 6.3-9. Histogram plots of 2012 HSC observations for juvenile Chinook salmon
normalized to the maximum frequency equal to 1.0 for depth (top), velocity (middle), and
substrate (bottom) microhabitat components, Susitna River, Alaska. ................................ 294
Figure 6.3-10. Histogram plots of 2012 HSC observations for juvenile Chinook salmon
normalized to the maximum frequency equal to 1.0 for depth (top), velocity (middle), and
substrate (bottom) microhabitat components, Susitna River, Alaska. ................................ 295
Figure 6.3-11. Histogram plots of 2012 HSC observations for sockeye salmon spawning
normalized to the maximum frequency equal to 1.0 for depth (top), velocity (middle), and
substrate (bottom) microhabitat components, Susitna River, Alaska. ................................ 296
Figure 6.3-12. Histogram plots of 2012 HSC observations for fry sockeye salmon normalized to
the maximum frequency equal to 1.0 for depth (top), velocity (middle), and substrate
(bottom) microhabitat components, Susitna River, Alaska. ............................................... 297
Figure 6.3-13. Histogram plots of 2012 HSC observations for pink salmon spawning normalized
to the maximum frequency equal to 1.0 for depth (top), velocity (middle), and substrate
(bottom) microhabitat components, Susitna River, Alaska. ............................................... 298
Figure 6.3-14. Histogram plots of 2012 HSC observations for chum salmon spawning
normalized to the maximum frequency equal to 1.0 for depth (top), velocity (middle), and
substrate (bottom) microhabitat components, Susitna River, Alaska. ................................ 299
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Figure 6.3-15. Histogram plots of 2012 HSC observations for fry chum salmon normalized to
the maximum frequency equal to 1.0 for depth (top), velocity (middle), and substrate
(bottom) microhabitat components, Susitna River, Alaska. ............................................... 300
Figure 6.3-16. Histogram plots of 2012 HSC observations for fry coho salmon normalized to the
maximum frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom)
microhabitat components, Susitna River, Alaska. .............................................................. 301
Figure 6.3-17. Histogram plots of 2012 HSC observations for juvenile coho salmon normalized
to the maximum frequency equal to 1.0 for depth (top), velocity (middle), and substrate
(bottom) microhabitat components, Susitna River, Alaska. ............................................... 302
Figure 6.3-18. Histogram plots of 2012 HSC observations for adult artic grayling normalized to
the maximum frequency equal to 1.0 for depth (top), velocity (middle), and substrate
(bottom) microhabitat components, Susitna River, Alaska. ............................................... 303
Figure 6.3-19. Histogram plots of 2012 HSC observations for juvenile arctic grayling
normalized to the maximum frequency equal to 1.0 for depth (top), velocity (middle), and
substrate (bottom) microhabitat components, Susitna River, Alaska. ................................ 304
Figure 6.3-20. Histogram plots of 2012 HSC observations for fry arctic grayling normalized to
the maximum frequency equal to 1.0 for depth (top), velocity (middle), and substrate
(bottom) microhabitat components, Susitna River, Alaska. ............................................... 305
Figure 6.3-21. Histogram plots of 2012 HSC observations for adult rainbow trout normalized to
the maximum frequency equal to 1.0 for depth (top), velocity (middle), and substrate
(bottom) microhabitat components, Susitna River, Alaska. ............................................... 306
Figure 6.3-22. Histogram plots of 2012 HSC observations for juvenile humpback whitefish
normalized to the maximum frequency equal to 1.0 for depth (top), velocity (middle), and
substrate (bottom) microhabitat components, Susitna River, Alaska. ................................ 307
Figure 7.1-1. Locations of instream flow habitat modeling sites established in the Middle
Segment of the Susitna River during the 1980s Su-Hydro studies. .................................... 308
Figure 7.1-2. Locations of instream flow habitat modeling sites established in the Lower
Segment of the Susitna River during the 1980s Su-Hydro studies. .................................... 309
Figure 7.1-3. Locations of instream flow transects and model types applied during the 1980s Su-
Hydro studies in lower and upper Side Channel 11 and in Slough 11, located near Gold
Creek. Breaching flows based on those studies are also depicted for various side channel
and side slough habitats. ..................................................................................................... 310
Figure 7.1-4. Locations of instream flow transects and model types applied during the 1980s Su-
Hydro studies in the Whiskers Slough complex. Breaching flows based on those studies are
also depicted for various side channel and side slough habitats. ........................................ 311
Figure 7.1-5. Illustration of the grid and cell sampling scheme employed at RJHAB modeling
study sites. Sources: Marshall et al. (1984). ...................................................................... 312
Figure 7.1-6. Conceptual figures illustrating procedure used for deriving non-modeled specific
area (sa) Habitat Availability Index curve using a modeled curve in a mainstem (ms)
habitat, as applied during the 1980s Su-Hydro Studies (see Aaserude et al. 1985; Steward et
al. 1985). The procedure included lateral shifts (upper figure) due to adjustments from
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differences in breaching flows (Qms, Qsa) as well as vertical shifts (middle figure)
proportional to structural habitat indices (SHIsa/SHIms) to account for differences in
structural habitat quality. The lower figure shows final hypothetical modeled and non-
modeled specific area curves. Source: Aaserude et al. (1985)........................................... 313
Figure 7.2-1. Exceedance flow values (USGS gage at Gold Creek), target sampling flows and
anticipated model extrapolation range for the Susitna River, Alaska. ................................ 314
Figure 7.2-2. Conceptual layout of 2-D coarse and fine mesh modeling within the proposed
Whiskers Slough Focus Area. ............................................................................................. 315
Figure 7.2-3. Conceptual framework of the varial zone model. ................................................ 316
Figure 8.1-1. Mean daily intergravel and surface water temperature data from a spawning site in
Slough 8A. .......................................................................................................................... 317
Figure 8.1-2. Upwelling locations in the Middle Susitna River reported by Estes and Schmidt
(1983). ................................................................................................................................. 318
Figure 8.1-3. Upwelling locations at Slough 8A reported by Estes and Schmidt (1983). ......... 319
Figure 8.1-4. Upwelling locations at Slough 21 reported by Estes and Schmidt (1983). .......... 320
Figure 8.1-5. Turbidity and temperature measured at the Gold Creek Station and discharge
measured at the Talkeetna Station during 1984. ................................................................. 321
Figure 8.1-6. Range of turbidity during breached and unbreached conditions at twelve side
sloughs and side channels. .................................................................................................. 322
Figure 8.1-7. Hypothetical slough with delineated habitat zones. ............................................. 323
Figure 8.1-8. Typical arrangement of transects, grids, and cells at a JAHS site. ...................... 324
Figure 8.1-9. Percent size composition of fine substrate (<0.08 in. diameter) of McNeil samples
collected in various habitat types in the middle Susitna River, Alaska. ............................. 325
Figure 8.1-10. Percent size composition of fine substrate (<0.08 in. diameter) in McNeil samples
collected at chum salmon redds during May 1984 in study sites of middle Susitna River,
Alaska. ................................................................................................................................ 325
Figure 8.1-11. Relationship between percent survival of salmon embryos and the percent of fine
substrate (<0.08 in. diameter) within Whitlock-Vibert Boxes removed from artificial redds
within selected habitats of the middle Susitna River, Alaska. ............................................ 326
APPENDICES
Appendix 1. Index of Location Names and River Mile
Appendix 2. Listing of Fish and Aquatic Studies Documents and Reports Resulting from the
1980s Su-Hydro Project
Appendix 3. Summary of 1980s Instream Flow Habitat Modeling Sites
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LIST OF ACRONYMS AND SCIENTIFIC LABELS
Term Definition
Accretion
1. Addition of flows to the total discharge of the stream channel, which may come
from tributaries, springs, or seeps. 2. Increase of material such as silt, sand, gravel,
water.
Active floodplain The flat valley floor constructed by river during lateral channel migration and
deposition of sediment under current climate conditions.
Adaptive management A process whereby management decisions can be changed or adjusted based on
additional biological, physical or socioeconomic information.
Adfluvial Fish that spend a part of their life cycle in lakes and return to rivers and streams to
spawn.
Adult Sexually mature individuals of a species.
Age-0 juvenile
The description of an organism that, in its natal year, has developed the anatomical
and physical traits characteristically similar to the mature life stage, but without the
capability to reproduce.
Aggradation
1. Geologic process in which inorganic materials carried downstream are deposited
in streambeds, floodplains, and other water bodies resulting in a rise in elevation in
the bottom of the water body. 2. A state of channel disequilibrium, whereby the
supply of sediment exceeds the transport capacity of the stream, resulting in
deposition and storage of sediment in the active channel.
Anadromous Fish that mature in salt water but migrate to fresh water to spawn.
Annual flow
The total volume of water passing a given point in one year. Usually expressed as
a volume (such as acre-feet) but may be expressed as an equivalent constant
discharge over the year, such as cubic feet per second.
Armoring
1. The formation of an erosion-resistant layer of relatively large particles on the
surface of a streambed or stream bank that results from removal of finer particles by
erosion, and which resists degradation by water currents. 2. The application of
materials to reduce erosion. 3. The process of continually winnowing away smaller
substrate material and leaving a veneer of larger ones.
Average daily flow
The long-term average annual flow divided by the number of days in the year
usually expressed as an equivalent constant discharge such as cubic feet per
second. In some settings, the value can be used to represent only the portion of the
daily flow values in a defined period such as those that occur within a calendar
month.
Bank
The sloping land bordering a stream channel that forms the usual boundaries of a
channel. The bank has a steeper slope than the bottom of the channel and is
usually steeper than the land surrounding the channel.
Bathymetric Related to the measurement of water depth within a water body.
Bedload Material moving on or near the streambed and frequently in contact with it.
Benthic Associated with the bottom of a body of water.
Benthic macroinvertebrates
Animals without backbones, living in or on the sediments, a size large enough to be
seen by the unaided eye, and which can be retained by a U.S. Standard No. 30
sieve (28 openings/inch, 0.595-mm openings). Also referred to as benthos, infauna,
or macrobenthos.
Braid Pattern of two or more interconnected channels typical of alluvial streams.
Breaching flow The mainstem river flow that overtops the inlet elevation of a side channel.
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Term Definition
Calibration
The validation of specific measurement techniques and equipment, or the
comparison between measurements. In the context of PHABSIM, calibration is the
process of adjusting input variables to minimize the error between predicted and
observed water surface elevations.
Capillary fringe The subsurface layer in which groundwater seeps up from a water table by capillary
action to fill soil pores.
Catch per unit effort (CPUE)
The quantity of fish caught (in number or in weight) with one standard unit of fishing
effort. CPUE is often considered an index of fish biomass (or abundance).
Sometimes referred to as catch rate. CPUE may be used as a measure of
economic efficiency of fishing as well as an index of fish abundance.
Channel A natural or artificial watercourse that continuously or intermittently contains water,
with definite bed and banks that confine all but overbank streamflows.
Confidence interval The computed interval with a given probability that the true value of the statistic –
such as a mean, proportion, or rate – is contained within the interval.
Confinement Ratio of valley width (VW) to channel width (CW). Confined channel VW:CW <2;
Moderately confined channel VW:CW 2-4; Unconfined channel VW:CW >4.
Confluence The junction of two or more streams.
Connectivity Maintenance of lateral, longitudinal, and vertical pathways for biological,
hydrological, and physical processes.
Cover
Structural features (e.g., boulders, log jams) or hydraulic characteristics (e.g.,
turbulence, depth) that provide shelter from currents, energetically efficient feeding
stations, and/or visual isolation from competitors or predators.
Cross section A plane across a stream channel perpendicular to the direction of water flow.
Cross-sectional area The area of the stream's vertical cross section, perpendicular to flow.
Cubic feet per second (cfs)
A standard measure of the total amount of water passing by a particular location of
a river, canal, pipe or tunnel during a one second interval. One cfs is equal to
7.4805 gallons per second, 28.31369 liters per second, 0.028 cubic meters per
second, or 0.6463145 million gallons per day (mgd). Also called second-feet.
Current meter Instrument used to measure the velocity of water flow in a stream, measured in
units of length per unit of time, such as feet per second (fps).
Datum A geometric plane of known or arbitrary elevation used as a point of reference to
determine the elevation, or change of elevation, of another plane (see gage datum).
Decision support system (DSS)
Tools developed to evaluate alternative flow scenarios in support of water control
decisions; can include matrices that array differences among alternative flow
regimes by calculating values of indicator variables representing different habitat
characteristics or processes of the riverine ecosystem.
Degradation
1. A decline in the viability of ecosystem functions and processes. 2. Geologic
process by which streambeds and floodplains are lowered in elevation by the
removal of material (also see down cutting).
Delta A low, nearly flat accumulation of sediment deposited at the mouth of a river or
stream, commonly triangular or fan-shaped.
Dendrochronology The science of dating woody species (Fritts 1976).
Density Number of individuals per unit area.
Deposition The settlement or accumulation of material out of the water column and onto the
streambed.
Depth Water depth at the measuring point (station).
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Term Definition
Dewater Remove or drain the water from a stream, pond or aquifer.
DIHAB Direct Input Habitat model
Discharge
The rate of streamflow or the volume of water flowing at a location within a specified
time interval. Usually expressed as cubic meters per second (cms) or cubic feet per
second (cfs).
Dissolved oxygen (DO)
The amount of gaseous oxygen (O2) dissolved in the water column. Oxygen gets
into water by diffusion from the surrounding air, by aeration (rapid movement), and
as a waste product of photosynthesis. More than 5 parts oxygen per million parts
water is considered healthy; below 3 parts oxygen per million is generally stressful
to aquatic organisms.
Disturbance regime
Floodplain vegetation disturbance types found within the Susitna River Study Area
corridor include: channel migration (erosion and depositional processes), ice
processes (shearing impacts, flooding and freezing), herbivory (beaver, moose, and
hare), wind, and, to an infrequent extent, fire. Floodplain soil disturbance is
primarily ice shearing and sediment deposition.
Drainage area The total land area draining to any point in a stream. Also called catchment area,
watershed, and basin.
Ecosystem Any complex of living organisms interacting with nonliving chemical and physical
components that form and function as a natural environmental unit.
Electrofishing A biological collection method that uses electric current to facilitate capturing fishes.
Embeddedness
The degree that larger particles (boulders, rubble, or gravel) are surrounded or
covered by fine sediment. Usually measured in classes according to percent of
coverage.
Emergent vegetation An emergent plant is one which grows in water but which pierces the surface so that
it is partially in air. Collectively, such plants are emergent vegetation.
Euphotic zone Surface layer of an ocean, lake, or other body of water through which light can
penetrate. Also known as the zone of photosynthesis.
FLIR Forward looking infrared (FLIR) is an imaging technology that senses infrared
radiation. Can be used for watershed temperature monitoring.
Flood Any flow that exceeds the bankfull capacity of a stream or channel and flows out on
the floodplain.
Floodplain
1. The area along waterways that is subject to periodic inundation by out-of-bank
flows. 2. The area adjoining a water body that becomes inundated during periods of
over-bank flooding and that is given rigorous legal definition in regulatory programs.
3. Land beyond a stream channel that forms the perimeter for the maximum
probability flood. 4. A relatively flat strip of land bordering a stream that is formed by
sediment deposition. 5. A deposit of alluvium that covers a valley flat from lateral
erosion of meandering streams and rivers.
Floodplain vegetation − groundwater /
surface water regime functional groups
Assemblages of plants that have established and developed under similar
groundwater and surface water hydrologic regimes.
Flushing flow A stream discharge with sufficient power to remove silt and sand from a
gravel/cobble substrate but not enough power to remove gravels.
Focus Area Areas selected for intensive investigation by multiple disciplines as part of the
Instream Flow Study.
Fry A recently hatched fish. Sometimes defined as a young juvenile salmonid with
absorbed egg sac, less than 60 mm in length.
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Term Definition
Gaging station A specific site on a stream where systematic observations of streamflow or other
hydrologic data are obtained.
Geographic information system (GIS)
An integrated collection of computer software and data used to view and manage
information about geographic places, analyze spatial relationships, and model
spatial processes. A GIS provides a framework for gathering and organizing spatial
data and related information so that it can be displayed and analyzed. In the
simplest terms, GIS is the merging of cartography, statistical analysis, and database
technology.
Geomorphic mapping
A map design technique that defines, delimits and locates landforms. It combines a
description of surface relief and its origin, relative age, and the environmental
conditions in which it formed. This type of mapping is used to locate and
differentiate among relief forms related to geologic structure, internal dynamics of
the lithosphere, and landforms shaped by external processes governed by the bio-
climate environment.
Global positioning system (GPS)
A system of radio-emitting and -receiving satellites used for determining positions
on the earth. The orbiting satellites transmit signals that allow a GPS receiver
anywhere on earth to calculate its own location through trilateration. Developed and
operated by the U.S. Department of Defense, the system is used in navigation,
mapping, surveying, and other applications in which precise positioning is
necessary.
Gradient The rate of change of any characteristic, expressed per unit of length (see Slope).
May also apply to longitudinal succession of biological communities.
Groundwater In general, all subsurface water that is distinct from surface water; specifically, that
part which is in the saturated zone of a defined aquifer.
Habitat guild Groups of species that share common characteristics of microhabitat use and
selection at various stages in their life histories.
Habitat suitability criteria (HSC)
A graph/mathematical equation describing the suitability for use of areas within a
stream channel related to water depth, velocity and substrate by various
species/lifestages of fish.
Habitat suitability index (HSI)
An HSI is a numerical index that represents the capacity of a given habitat to
support a selected species. HSI model results represent the interactions of the
habitat characteristics and how each habitat relates to a given species. The value is
to serve as a basis for improved decision making and increased understanding of
species-habitat relationships.
Hydraulic control A horizontal or vertical constriction in the channel, such as the crest of a riffle, which
creates a backwater effect.
Hydraulic head A measure of energy or pressure, expressed in terms of the vertical height of a
column of water that has the same pressure difference.
Hydraulic model A computer model of a segment of river used to evaluate stream flow characteristics
over a range of flows.
Hydrograph A graph showing the variation in discharge over time.
IFG Instream Flow Group
IFIM Instream Flow Incremental Methodology
Incised
Lowering of the streambed by erosion that occurs when the energy of the water
flowing through a stream reach exceeds that necessary to erode and transport the
bed material.
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page xx March 2013
Term Definition
Incremental methodology
The process of developing an instream flow policy that incorporates multiple or
variable rules to establish, through negotiation, flow-window requirements or
guidelines to meet the needs of an aquatic ecosystem, given water supply or other
constraints. It usually implies the determination of a habitat-discharge relation for
comparing streamflow alternatives through time.
Instream flow The rate of flow in a stream channel at any time of year.
Intergravel Intergravel refers to the subsurface environment within the river bed.
Invertebrate All animals without a vertebral column; for example, aquatic insects.
Isotopic dating Direct dating using analyses of stable isotopes.
Large woody debris (LWD) Pieces of wood larger than 10 feet long and 6 inches in diameter, in a stream
channel. Minimum sizes vary according to stream size and region.
LiDAR Light detection and ranging. An optical remote sensing technology that can
measure the distance to a target, can be used to create a topographic map.
Life stage
An arbitrary age classification of an organism into categories relate to body
morphology and reproductive potential, such as spawning, egg incubation, larva or
fry, juvenile, and adult.
Macroinvertebrate An invertebrate animal without a backbone that can be seen without magnification.
Main channel
Main Channel Habitat Types
Main Channel: Single dominant main channel
Split Main Channel: Less than 3 distributed dominant channels
Braided Main Channel: Greater than 3 distributed dominant channels
Side Channel: Channel that is turbid and connected to the active main channel but
represents non-dominant proportion of flow
Tributary Mouth: Clear water areas that exist where tributaries flow into the
Susitna River main channel or side channel habitats
Mainstem
Mainstem refers to the primary river corridor, as contrasted to its tributaries.
Mainstem habitats include the main channel, split main channels, side channels,
tributary mouths, and off-channel habitats.
Manning’s n A measure of channel roughness.
Mesohabitat
A discrete area of stream exhibiting relatively similar characteristics of depth,
velocity, slope, substrate, and cover, and variances thereof (e.g., pools with
maximum depth <5 ft, high gradient rimes, side channel backwaters).
Microhabitat
Small localized areas within a broader habitat type used by organisms for specific
purposes or events, typically described by a combination of depth, velocity,
substrate, or cover.
Non-native
Not indigenous to or naturally occurring in a given area. Presence is usually
attributed to intentional or unintentional introduction by humans. Non-native species
are also termed “exotic” species.
Nose velocity The velocity at the approximate point vertically in the channel where a fish is
located.
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page xxi March 2013
Term Definition
Off-channel
Those bodies of water adjacent to the main channel that have surface water
connections to the main river at some discharge levels.
Off-channel Habitat Types
Side Slough: Overflow channel contained in the floodplain, but disconnected from
the main channel. Has clear water.2
Upland Slough: Similar to a side slough, but contains a vegetated bar and is rarely
overtopped by mainstem flow. Has clear water. 2
Backwater: Found along channel margins and generally within the influence of the
active main channel. Water is not clear.
Beaver Complex: Complex ponded water body created by beaver dams
Peak load The greatest of all load demands on an interconnected electric transmission
network occurring in a specified period of time.
Period of record The length of time for which data for an environmental variable have been collected
on a regular and continuous basis.
pH
A measure of the acidity or basicity of a solution. Pure water is said to be neutral,
with a pH close to 7.0 at 25 °C (77 °F). Solutions with a pH less than 7 are said to
be acidic, and solutions with a pH greater than 7 are said to be basic or alkaline.
PHABSIM
(pronounced P-HAB-SIM) The Physical HABitat SIMulation system; a set of
software and methods that allows the computation of a relation between streamflow
and physical habitat for various life stage of an aquatic organism or a recreational
activity.
Physical habitat Those abiotic factors such as depth, velocity, substrate, cover, temperature, water
quality that make up some of an organism's living space.
Pool Part of a stream with reduced velocity, often with water deeper than the surrounding
areas, which is usable by fish for resting and cover.
Powerhouse A structure that houses the turbines, generators, and associated control equipment.
PRM
Project River Mile(s) based on the digitized wetted width centerline of the main
channel from 2012 Matanuska-Susitna Borough digital orthophotos. PRM 0.0 is
established as mean lower low water of the Susitna River confluence at Cook Inlet.
Process domains Define specific geographic areas in which various geomorphic processes govern
habitat attributes and dynamics (Montgomery 1999).
Q Hydrological abbreviation for discharge, usually presented as cfs (cubic feet per
second) or cms (cubic meters per second). Flow (discharge at a cross-section).
Radiotelemetry Involves the capture and placement of radio-tags in adult fish that allow for the
remote tracking of movements of individual fish.
Ramping rate The rate of change in discharge (typically inches per hour) below a hydroelectric
facility that is fluctuating flow releases.
Recruitment The number of new juvenile fish reaching a certain size/age class; connotes the
process whereby juveniles survive and mature into adults.
Redd The spawning ground or nest of various fishes.
Refugia
An area protected from disturbance and exposure to adverse environmental
conditions where fish or other animals can find shelter from sudden flow surges,
adverse water quality, or other short-duration disturbances.
Regime The general pattern (magnitude and frequency) of flow or temperature events
through time at a particular location (such as snowmelt regime, rainfall regime).
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page xxii March 2013
Term Definition
Reservoir A body of water, either natural or artificial, that is used to manipulate flow or store
water for future use.
Restoration
To return a stream, river, or lake to its natural, predevelopment form and function.
Restoration typically eliminates the human influence that degraded or destroyed
riverine processes and characteristics.
Riffle
A fast water habitat with turbulent, shallow flow over submerged or partially
submerged gravel and cobble substrates. Gradients are approximately 2 to less
than 4%.
Riparian Pertaining to anything connected with or adjacent to the bank of a stream or other
body of water.
Riparian process domain Define specific geographic areas in which various geomorphic processes govern
floodplain habitat attributes and dynamics.
Riparian vegetation Vegetation that is dependent upon an excess of moisture during a portion of the
growing season on a site that is perceptively more moist than the surrounding area.
Riparian zone A stream and all the vegetation on its banks that is influenced by the presence of
the stream, including surface flow, hyporheic flow and microclimate.
River A large stream that serves as the natural drainage channel for a relatively large
catchment or drainage basin.
River corridor
A perennial, intermittent, or ephemeral stream and adjacent vegetative fringe. The
corridor is the area occupied during high water and the land immediately adjacent,
including riparian vegetation that shades the stream, provides input of organic
debris, and protects banks from excessive erosion.
River mile (RM) The distance of a point on a river measured in miles from the river's mouth along
the low-water channel.
RJHAB Resident Juvenile Habitat model
Scour The localized removal of material from the streambed by flowing water. This is the
opposite of fill.
Sediment Solid material, both mineral and organic, that is in suspension in the current or
deposited on the streambed.
Side channel
Lateral channel with an axis of flow roughly parallel to the mainstem, which is fed by
water from the mainstem; a braid of a river with flow appreciably lower than the
main channel. Side channel habitat may exist either in well-defined secondary
(overflow) channels, or in poorly-defined watercourses flowing through partially
submerged gravel bars and islands along the margins of the mainstem.
Sinuosity
The ratio of channel length between two points on a channel to the straight-line
distance between the same two points. The amount of bending, winding and
curving in a stream or river.
Slope
The inclination or gradient from the horizontal of a line or surface. The degree of
inclination can be expressed as a ratio, such as 1:25, indicating one unit rise in 25
units of horizontal distance or as 0.04 height per length. Often expressed as a
percentage and sometimes also expressed as feet (or inches) per mile.
Smolt An adolescent salmon which has metamorphosed and which is found on its way
downstream toward the sea.
Smoltification The physiological changes anadromous salmonids and trout undergo in freshwater
while migrating toward saltwater that allow them to live in the ocean.
Spawning The depositing and fertilizing of eggs by fish and other aquatic life.
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page xxiii March 2013
Term Definition
Split channel
A river having numerous islands dividing the flow into two channels. The islands
and banks are usually heavily vegetated and stable. The channels tend to be
narrower and deeper and the floodplain narrower than for a braided system.
Stage The distance of the water surface in a river above a known datum.
Stage of zero flow (SZF) No discharge flowing through the cross-section if water stage is equal or lower than
SZF. Usually SZF is the channel invert, the lowest point of the channel.
Stage-discharge relationship The relation between the water-surface elevation, termed stage (gage height), and
the volume of water flowing in a channel per unit time.
Stranding Stranding refers to the beaching of fish and other aquatic organisms on low gradient
channel bed as a result of declining river stage.
Streambed The bottom of the stream channel; may be wet or dry.
Substrate
The material on the bottom of the stream channel, such as rocks or vegetation.
Proposed substrate classification system for use in development of HSC/HIS curves
for the Susitna-Watana Project.
Code Substrate Type Size (Inches) Size (mm)
1 Silt, Clay, or Organic <0.01 <0.1
2 Sand 0.01-0.10 0.1-2.0
3 Small Gravel 0.10-0.30 2.0-8.0
4 Medium Gravel 0.30-1.25 8.0-32
5 Large Gravel 1.25-2.50 32-64
6 Small Cobble 2.50-5.0 64-128
7 Large Cobble 5.0-10.0 128-256
8 Boulder >10.0 >256
9 Bedrock
Suitability A generic term used in IFIM to indicate the relative quality of a range of
environmental conditions for a target species.
Temporal variability Pertaining to, or involving the nature of time, occurrence in time, and variability in
occurrence over some increment in time (e.g., diurnally, daily, monthly, annually).
Thalweg The deepest channel of a watercourse.
Time step The interval over which elements in a time series are averaged.
Time-series analysis
Analysis of the pattern (frequency, duration, magnitude, and time) of time-varying
events. These events may be discharge, habitat areas, stream temperature,
population factors, economic indicators, power generation, and so forth.
Transferability
1. Applicability of a model (e.g., habitat suitability criteria) to settings or conditions
that differ from the setting or conditions under which the model was developed. 2.
Applicability of data obtained from a remote source (e.g., a meteorological station)
for use at a location having different environmental attributes.
Trapping Trapping is the isolation of fish and other aquatic organisms in pockets of water with
no access to the free-flowing surface water as a result of declining river stage.
Tributary A stream feeding, joining, or flowing into a larger stream (at any point along its
course or into a lake). Synonyms: feeder stream, side stream.
Turbidity A measure of the extent to which light passing through water is reduced due to
suspended materials.
Varial zone
The area of river channel bed exposed to frequent inundation and dewatering
caused by daily flow fluctuations associated with hydropower load-following
operations.
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page xxiv March 2013
Term Definition
Velocity The distance traveled by water in a stream channel divided by the time required to
travel that distance.
Velocity adjustment factor (VAF) Qsimulated/Qtrial, where Qtrial is the discharge computed by PHABSIM.
Vertical A location along a transect across a river where microhabitat-related data are
collected.
Weighted usable area (WUA) The wetted area of a stream weighted by its suitability for use by aquatic organisms
or recreational activity.
Wetted perimeter The length of the wetted contact between a stream of flowing water and the stream
bottom in a plane at right angles to the direction of flow.
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 March 2013
1. INTRODUCTION
The construction and operation of the Susitna – Watana Hydroelectric Project (Project) (Federal
Energy Regulatory Commission (FERC No. 14241) will affect Susitna River flows downstream
of the dam; the degree of these effects will ultimately depend on final Project design and
operating characteristics. The potential alteration in flows will influence downstream
resources/processes, including fish and aquatic biota and their habitats, channel form and
function including sediment transport, water quality, groundwater/surface water interactions, ice
dynamics, and riparian and wildlife communities (AEA 2011). Determining the effects of
Project operations on the different resources and processes is the focus of a series of studies that
have been proposed by Alaska Energy Authority (AEA) as part of the FERC Integrated
Licensing Process (ILP). Those studies have been described in detail within the Revised Study
Plan (RSP) that was submitted by AEA to the FERC in December 2012.
The development of those study plans benefited from previous studies that were completed in the
early 1980s in conjunction with the then proposed development of an earlier Susitna
Hydroelectric Project (Susitna-Hydroelectric (Su-Hydro) Project (FERC No. 7114)). That
project involved a two-dam configuration with a different proposed operational plan (see Section
2 below). Nevertheless, flow regulation was a paramount issue relative to effects on different
resources (Perry and Trihey 1981) and therefore detailed studies were commissioned by the
Alaska Power Authority (APA) with the majority conducted over a five year period (1981-1985).
The extent and details of many of those studies were provided in the Draft Environmental Impact
Statement (FERC 1984) along with companion appendices and attachments in the way of Alaska
Department of Fish and Game (ADF&G) reports. A gap analysis conducted by HDR (2011)
summarized some of the data and provided an initial listing of salient reports and data that
warranted more detailed evaluations.
A more focused review of existing reports and data specific to the Su-Hydro Project proposed in
the 1980s was initiated by AEA in 2012 that included the identification, acquisition, and
compilation of study plans, reports, data, maps, drawings, photographs, and technical
correspondence pertaining to the 1980s Su-Hydro Project. A substantial amount of this
information had already been provided to and made available through the Alaska Resources
Library and Information Services (ARLIS), and AEA has identified and is working with ARLIS
in acquiring the majority of original files, documents, maps, drawings, and other information that
had been archived in several locations in Alaska. These documents are in a variety of formats
including textual, microfiche, and maps. The majority of these documents will be housed in the
ARLIS library in Anchorage, Alaska (some are available online through the University of
Alaska, Fairbanks library) and will be made available either electronically or by on -site review to
interested parties, licensing participants, and Project team members. AEA has established the
following link to the Su-Hydro documents via ARLIS http://www.susitna-
watanahydro.org/type/documents/.
As part of the 2012 effort, AEA also commissioned the targeted review of reports, data, and
other information specific to the 1980s studies of fish, fish habitats, and instream flow-related
assessments. These documents include 83 separate volumes containing descriptions of field
studies and reports with tabular data, figures, and maps. The reports describe studies that were
focused on a wide range of interrelated topics designed to provide information that would allow
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 March 2013
for an evaluation of the potential effects of the Su-Hydro Project operations on downstream fish
and aquatic resources and habitats. These included studies focused on:
Adult salmon passage in sloughs and side channels
Adult salmon spawn timing and distribution
Salmon Habitat Suitability Criteria
Salmon spawning habitat evaluation
Juvenile salmon abundance and distribution including winter studies
Resident fish abundance, distribution, and life history
Channel geometry investigations
Groundwater upwelling detection; and
Hydrological investigations and modeling of anadromous and resident fish habitat
That work has been completed and has resulted in the preparation of six Technical
Memoranda (TMs) that summarize the salient fish and instream flow-related information
from those studies. For convenience, and because of their interrelationships, the TMs have
been compiled and are included together within this compendium document. The TMs are
presented in the following order:
Technical Memorandum – River Stratification and Study Site Selection Process: 1980s
Studies and 2013-2014 Studies – discusses the study site selection process applied during
the 1980s studies that allows for a comparison with the process proposed for the 2013-
2014 studies.
Technical Memorandum – Summary of Fish Distribution and Abundance Studies
Conducted during the 1980s Su-Hydro Project – summarizes the methods used and study
sites sampled for evaluating fish distributions in the Susitna River in the 1980s. This TM
does not have a corollary section for the 2013-2014 studies since there are 12 separate
fish related studies proposed for 2013-2014 (see RSP Sections 9.5 through 9.16).
Technical Memorandum – Selection of Target Species and Development of Species
Periodicity Information:1980s Studies and 2013-2014 Studies – summarizes the data and
information that was collected in the 1980s that was used in identifying target species and
developing species periodicities, and provides a general overview of the approach for
developing this information in the 2013-2014 studies.
Technical Memorandum – Development of Habitat Suitability Curves and Habitat
Utilization Information: 1980s Studies and 2013-2014 Studies – describes methods used
for collecting HSC data in the 1980s and provides a listing of HSC curves that were
developed; the TM also provides an overview of the approach for developing this
information in the 2013-2014 studies.
Technical Memorandum – Review of Habitat Modeling Methods: 1980s Studies and
2013-2014 Studies – describes the different instream flow related methods that were
applied during the 1980s studies and provides an overview of the approaches that will be
applied in the 2013-2014 studies.
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 3 March 2013
Technical Memorandum – Biologically Relevant and Flow Dependent Physical
Processes: 1980s Studies and 2013-2014 Studies – discusses various physical processes
that were considered biologically relevant during the 1980s studies and that are linked to
surface flow conditions; these processes are also briefly discussed relative to the 2013-
2014 studies.
For convenience, all figures and tables, and a comprehensive listing of all references have been
placed at the end of the compendium. The compendium includes three appendices:
Appendix 1 – index of location names and river miles used in the compendium;
Appendix 2 – a listing of all articles and reports cited in this compendium along with a
hyperlink to the documents via ARLIS; and
Appendix 3 – summary document that describes instream flow study sites and general
modeling approaches used during the 1980s instream flow studies.
It should be noted that the TMs presented herein borrow extensively from the reports and
documents that were prepared by the many scientists and researchers involved during the 1980s
studies. This not only included borrowing from the text and narratives of the reports but in many
cases, specific figures or tables that proved especially useful for explaining both methodologies
as well as results. Throughout this process, special attention was placed on making sure that the
paraphrasing and/or direct quoting or use of materials from these documents was properly cited.
However, in spite of this, there may still be a few instances where such citations were missing or
improperly assigned and for this we apologize to the respective authors.
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 4 March 2013
2. BRIEF HISTORY OF THE 1980S SUSITNA PROJECT
The Susitna Hydroelectric project, as proposed in the 1980s consisted of a two – dam complex
that was scheduled for completion over a 21 year period (Trihey and Associates, and Entrix
(1985) in three stages. The two dams included an upper Watana Dam located at RM1 184 (PRM
187.5) that was to be constructed first (Stage 1), with a second dam, Devils Canyon Dam located
at RM 152 about 32 miles downstream from Watana Dam that was to follow (Stage 2). Stage 3
was to involve raising the height of the Watana Dam, upgrading the four turbines and installing
two additional units. At completion, the project would have had a total installed capacity of
1,880 MW (HDR 2009). Construction of the Watana Dam complex was to have occurred over
an 8-9 year period commencing in 1985 with power generation to have begun in 1994.
Construction of the Devils Canyon Dam was to commence immediately in sequence with the
operation of the Watana Dam complex with initial site development beginning in 1994 with
major construction occurring over a six year period leading to project operations in 2002 (FERC
1984).
Operationally, the Watana Dam was to be operated as a baseload facility until Devils Canyon
operations commenced. At that time, Watana Dam operations were to shift to peak and reserve
operation which would allow for daily and hourly changes in flow to meet daily power demands.
The Devils Canyon Dam would then have been used as a re-regulating facility to smooth-out the
rapid flow fluctuations resulting from operation of the Watana Dam and allow for more stable
flow releases provided as part of baseload operations. Thus, the downstream flow releases from
the Devils Canyon Dam would not have the daily flow fluctuations associated with peaking and
load-following operations of the upper development. In addition, because the Devils Canyon
Dam would create a reservoir that would inundate much of the river between the two dams, the
instream flow and riparian study efforts in the 1980s focused on the effects of flow releases to
the Susitna River downstream of the Devils Canyon Dam site, and the reach between the Devils
Canyon Dam and Watana Dam sites was not really considered as part of the instream flow and
fisheries studies.
The instream flow-related issues that were the focus of studies completed in the 1980s were
more concerned with determining the effects of changes in the timing and magnitude of flows on
the quantity and quality of fish habitats that would occur with the two dams as configured, rather
than flow fluctuations. Indeed, under the two dam configuration, daily/hourly flow fluctuations
would have been of little consequence to the Middle River resources below Devils Canyon.
Nevertheless, many of the flow related resource issues that were of concern in the 1980s are
similar to those raised for the newly proposed Susitna-Watana Hydroelectric Project (see Fish
1 The Project River Mile (PRM) system for the Susitna River was developed to provide a consistent and accurate method of
referencing features along the Susitna River. During the 1980s, researchers often referenced features by river mile without
identifying the source map or reference system. If a feature is described by river mile (RM) or historic river mile (HRM), then
the exact location of that feature has not been verified. The use of PRMs provides a common reference system and ensures tha t
the location of the feature can be verified. The PRM was constructed by digitizing the wetted width centerline of the main
channel from 2011 Matanuska-Susitna Borough digital orthophotos. Project River Mile 0.0 was established as mean low water
of the Susitna River confluence at Cook Inlet. A centerline corresponding to the channel thalweg was digitized upstream to the
river source at Susitna Glacier using data collected as part of the 2012 flow routing transect measurements. The resultant l ine is
an ArcGIS route feature class in which linear referencing tools may be applied. The use of RM or HRM will continue when
citing a 1980s study or where the location of the feature has not been verified. Features identified by PRM are associated with an
ArcGIS data layer and process, and signifies that the location has been verified and reproduced.
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 5 March 2013
and Aquatic Study Requests as posted at http://www.susitna-watanahydro.org/type/documents/).
In the early 1980s, an initial set of issues and concerns regarding the Susitna Hydroelectric
Project were identified as part of an organized survey of state and federal resource agencies and
stakeholders. These concerns were summarized and discussed in Perry and Trihey (1981) and
included comments that were separated into nine instream flow use categories including
commercial, recreational, water quality, water rights, estuary, riparian vegetation, fish and
wildlife, recreation and flow regime. Some of the comments and questions pertaining to fish and
the aquatic ecosystem effects included:
How would changes in flow regime, temperature, silt and water quality parameters affect
spawning, movement, outmigration, egg development and seasonal habitat use?
Would higher stream flow velocities associated with increased winter flows affect young-
of-the-year that migrate into the mainstem from tributaries during winter months?
What overwintering of juvenile and resident anadromous fish occurs in the main channel
and how would it be affected?
What will the effect be of reducing the sediment load and associated nutrients on
downstream biota?
Would the reduction of peak flows affect fishery utilization of side channels and
backwater areas?
What will the magnitude of flow change be under post-project conditions and how would
this affect access (fish) to tributaries?
Will the reduction in the seasonal variability of flow negatively impact the ability of the
river to cleanse itself of debris?
How will flows dampen in a downstream direction?
What is the relationship of groundwater levels to surface flows in the Susitna River?
What will the effect be of increased winter flows on icing?
How would the changes in flow affect sediment transport, bedload transport, stream
morphology and channel characteristics?
To address these questions, a series of studies were completed commencing in 1981 and
extending through 1986. Table 2.1-1 provides a general listing of the types of instream flow and
fish related studies that were completed as part of the Su-Hydro Project Fish and Aquatics Study
Program. More details concerning these studies are provided in other sections of this TM
Compendium, as well as in a synthesis document of 1980s fish data presented in R2 (2013a).
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 6 March 2013
3. TECHNICAL MEMORANDUM – RIVER STRATIFICATION AND
STUDY SITE SELECTION PROCESS: 1980S STUDIES AND 2013-
2014 STUDIES
As in all complex riverine instream flow studies, one of the first and perhaps most important
steps that occurs is the development of a study plan that spells out not only the study objectives
but also the methods and techniques that will be used to accomplish the objectives. A
fundamental part of that plan is typically devoted to specifying the locations/sites in which the
studies will be conducted. For large river systems such as the Susitna River, this generally
involves some form of stratification process in which the river is divided into reaches or
segments based on similarity of physical, hydrologic, and morphologic conditions. This process,
along with a habitat mapping component helps to determine both the number of study sites as
well as their spatial distribution and is integral for being able to make inferences from measured
to unmeasured sites. This TM describes the process that was used during the Su-Hydro 1980s
studies and then how that process factored into the stratification and classification approach
being proposed for the Susitna- Watana 2013-2014 studies.
3.1. Su-Hydro 1980s Studies – River Stratification, Classification
and Site Selection
The stratification approach applied for the 1980s Su-Hydro studies involved dividing the Susitna
River into segments, sub-reaches, and study sites based on hydrology, channel morphology,
tributary input, macro- and mesohabitat features, and fish use. At the broadest scale, the Susitna
River was divided into three segments following the historic river mile convention used at the
time:
1. Upper River – Representing that portion of the watershed above the proposed Devils
Canyon Dam (hereafter referred to as “Devils” Canyon) site at RM 152.
2. Middle River – Extending approximately 53.5 miles from RM 152 downstream through
Devils Canyon to the Three Rivers Confluence at RM 98.5.
3. Lower River – Extending 98.5 miles downstream from the Three Rivers Confluence to
Cook Inlet (RM 0).
These three breaks formed the first order level of stratification in the 1980s studies. It is
important to note that even with a two dam configuration, as was proposed for the Su-Hydro
Project (see above), the studies did not separate out a fourth segment that would have extended
for about 32 miles from Devils Canyon to the proposed Watana Dam site at RM 184. This was
presumably because the lower dam (Devils Canyon Dam) would represent the lowermost point
of the affected upper reach so that the lower boundary of that reach was anchored at that
location.
3.1.1. Middle River Stratification
For the Middle River, a second level of stratification was designated based on classifying
riverine-related habitats of the Susitna River into six macro-habitat categories consisting of
mainstem, side channel, side slough, upland slough, tributaries, and tributary mouths (Estes and
Vincent-Lang 1984; Klinger and Trihey 1984). The distribution and frequency of these habitats
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varied longitudinally within the river depending in large part on its confinement by adjoining
floodplain areas, size, and gradient. The habitat types were described by ADF&G with respect to
mainstem flow influence in the Susitna Hydroelectric Aquatic Studies Procedures Manual
(ADF&G 1984), also in Klinger and Trihey (1984) as follows, with additional clarification added
here where considered appropriate:
Mainstem habitat consisting of those portions of the Susitna River that normally convey
stream flow throughout the year. Both single and multiple channel reaches are included
in this habitat category. Groundwater and tributary inflows appear to be inconsequential
contributors to the overall characteristics of mainstem habitat. Mainstem habitat is
typically characterized by high water velocities and well-armored streambeds. Substrates
generally consist of boulder- and cobble-size materials with interstitial spaces filled with
a grout-like mixture of small gravels and glacial sands. Suspended sediment
concentrations and turbidity are high during summer due to the influence of glacial
meltwater. Stream flows recede in early fall and the mainstem clears appreciably in
October. An ice cover forms on the river in late November or December.
Side channel habitat consisting of those portions of the Susitna River that normally
convey stream flow during the open-water season but become appreciably dewatered
during periods of low flow. Side channel habitat may exist either in well-defined
overflow channels, or in poorly defined water courses flowing through partially
submerged gravel bars and islands along the margins of the mainstem river. Side channel
streambed elevations are typically lower than the mean monthly water surface elevations
of the mainstem Susitna River observed during June, July, and August. Side channel
habitats are characterized by shallower depths, lower velocities, and smaller streambed
materials than the adjacent habitat of the mainstem river.
Side slough habitat located in spring- or tributary-fed overflow channels between the
edge of the floodplain and the mainstem and side channels of the Susitna River and
usually separated from the mainstem and side channels by well-vegetated bars. An
exposed alluvial berm often separates the head of the slough from mainstem or side
channel flows. The controlling streambed/streambank elevations at the upstream end of
the side sloughs are slightly less than the water surface elevations of the mean monthly
flows of the mainstem Susitna River observed for June, July, and August. At
intermediate- and low-flow periods, the side sloughs convey clear water from small
tributaries and/or upwelling groundwater (Estes et al. 1981). These clear water inflows
are essential contributors to the existence of this habitat type. The water surface
elevation of the Susitna River generally causes a backwater to extend well up into the
slough from its lower end (Estes et al. 1981). Even though this substantial backwater
exists, the sloughs function hydraulically very much like small stream systems and
several hundred feet of the slough channel often conveys water independent of mainstem
backwater effects. At high flows the water surface elevation of the mainstem river is
sufficient to overtop the upper end of the slough (Estes et al. 1981). Surface water
temperatures in the side sloughs during summer months are principally a function of air
temperature, solar radiation, and the temperature of the local runoff.
Upland slough habitat differs from the side slough habitat in that the upstream end of
the slough is not interconnected with the surface waters of the mainstem Susitna River or
its side channels at less than bankfull flows. The upstream end can be vegetated with
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mature trees, although a morphologic signature of a converging inlet and gravel levee
closure can still be discerned. These sloughs are characterized by the presence of beaver
dams and an accumulation of silt covering the substrate resulting from the absence of
mainstem scouring flows. They are not truly “upland” in the geomorphic sense, but the
use of this nomenclature in the 1980s studies reflects the observation that the
understanding of floodplain and channel forming processes was in the early stage in
fisheries, where some variation in interpretation existed over what constituted a
floodplain versus an upland terrace (e.g., see Williams 1978). Essentially, the main
distinguishing characteristic between a “side” slough and an “upland” slough was the
level of high flow at which each was engaged.
Tributary habitat consists of the full complement of hydraulic and morphologic
conditions that occur in the tributaries. Their seasonal stream flow, sediment, and
thermal regimes reflect the integration of the hydrology, geology, and climate of the
tributary drainage. The physical attributes of tributary habitat are not dependent on
mainstem conditions.
Tributary mouth habitat extends from the uppermost point in the tributary influenced
by mainstem Susitna River or slough backwater effects to the downstream extent of the
tributary plume that extends into the mainstem Susitna River or slough (Estes et al.
1981).
A schematic of these types of habitats as applied in the 1980s studies is depicted in Figure 3.1-1.
These categories were also used by Trihey and Associates as part of instream flow modeling
studies for the Middle river (Aaserude et al. 1985).
3.1.2. Lower River Stratification and Classification
Because of the increased channel complexity, a three tiered approach was used for stratification
of the Lower River. This consisted of River Segment, Channel and Island Complexes, and
Macrohabitat types (R&M Consultants et al. (R&M and Trihey & Associates 1985). In terms of
River Segments, the Susitna River was divided into five segments based on river morphology
and hydrology (R&M and Trihey & Associates 1985). These segments included breaks in river
miles as follows: Segment 1: RM 98.5 to RM 78; Segment 2: RM 78 to RM 51; Segment 3: RM
51 to RM 42. 5; Segment 4: RM 42.5 to RM 28.5; and Segment V: RM 28.5 to RM 0 (see Figure
2.1 in R&M and Trihey & Associates 1985).
Within each River Segment, two primary classifications were made consisting of Mainstem
Channel and Side Channel complexes with each of these further divided into the following sub-
classifications:
Mainstem Channel – subclassified into: 1: Mainstem river consisting of mainstem
channel and main subchannels; and 2) Alluvial channel complexes consisting of areas of
broad gravel islands with numerous subchannels that dewater as flows decrease; and
Side Channel Complexes – subclassified into 1) Major side channels that were
designated in the 1980s studies as channels overtopped at mainstem flows of 13, 900 cfs
(the flow considered as the low winter flow during project operations (based on 1980s
project design) (these channels may collect groundwater seepage and tributary flow); 2)
Intermediate side channels that were distinguished based on the magnitude of the
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mainstem flows in which the side channels dewater; and 3) Minor side channels that
become dewatered over their entire length at flows of 36,600 cfs (the flow considered
transitional natural flow and project operation flow during May and September (based on
1980s project design) (R&M and Trihey & Associates 1985).
With respect to habitat types, a slightly different classification procedure was used that consisted
of eight general categories of which three (mainstem, side slough, and tributary mouth) were
common with the Middle River categories. These categories were described in R&M et al.
(1985) as follows:
“Mainstem habitats consisting of the thalweg channel, major subchannels, major
subchannels and alluvial island complexes”. This habitat type was generally outside of
areas that were generally considered as “representative areas” (R&M and Trihey &
Associates 1985).
Primary side channels consisting of “those channels which normally convey streamflow
throughout the entire year” (R&M and Trihey & Associates 1985). These side channels
exhibit characteristics similar to Middle river habitat types and are characterized by
glacially induced turbid water, high water velocities and few mid-channel bars.
Turbid backwater habitats consisting of nonbreached channels containing turbid water.
These habitats have “non-vegetated upper thalwegs that are overtopped during periods of
moderate to high mainstem discharge” and represent a “transitional habitat type between
breached secondary side channel habitats and nonbreached Clearwater or side slough
habitats” (R&M and Trihey & Associates 1985).
Clearwater habitats consisting of “nonbreached channels containing clear water that
dewater completely at a mainstem discharge of 13,900 cfs or higher. These channels
have non-vegetated upper thalwegs that are overtopped during periods of moderate to
high mainstem discharge. Groundwater and local surface runoff appear to supply water
to these areas at mainstem flows above 13,900 cfs” (R&M and Trihey & Associates
1985)
Side slough habitats consisting of clear water areas that are supplied via a mixture of
groundwater (upwelling) and local surface runoff. These clear water areas exist up to
mainstem flows of 13,900 cfs (R&M and Trihey & Associates 1985). Similar to the
Middle river, the side sloughs have non-vegetated upper thalwegs that are overtopped at
moderate to high mainstem discharges.
Tributary mouth habitats consisting of “clear water habitat that exist between the
downstream extent of a clear-water plume and upstream into the tributary, to the upper
extent of the backwater influence. The surface area depends on the discharge of both the
tributary and mainstem” (R&M and Trihey & Associates 1985).
Tributary habitats consisting of areas upstream of the tributary mouth habitat. This
habitat type was designated in the Lower River recognizing that tributary habitats may
increase dramatically when tributary flows into nonbreached side channel (side slough)
habitats and clear water tributary flows extend through the side channel to join the
Susitna River (R&M and Trihey & Associates 1985).
During the 1981 and 1982 studies, side sloughs and side channels were distinguished primarily
on their morphology. Side sloughs included (as noted above) an unvegetated berm at the head of
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the slough and were rarely overtopped. In contrast, a side channel conveyed mainstream flow
during most of the year. During 1983 and following years, if a berm was overtopped and a
channel conveyed mainstem flows it was then characterized as a side channel (Dugan et al.
1984). If the berm was not overtopped it was characterized as a side slough. Consequently,
during the latter years of the 1980s Fish and Aquatic Program an area may have been
characterized as a side channel during periods of high flows and a side slough during periods of
lower flows2.
3.1.3. Study and Sample Sites
Specific sites chosen for completion of the various studies by ADF&G between 1981 and 1985
varied from year to year and study to study. In general, sampling was relatively broad during
1981 and 1982, and more focused during 1983 to 1985. The 1981 Aquatic Habitat Studies were
focused on ‘Fishery Habitat’ evaluations and ‘Selected Habitat’ evaluations (Estes et al. 1981).
The Fishery Habitat evaluations collected point information on observed fish habitat use and
general habitat evaluations (water quality, hydrology, and mapping). The Selected Habitat
evaluations collected water quality, discharge, and mapping information at selected sloughs
between Talkeetna and Devils Canyon.
A total of 5 river reaches were delineated and 8 to 13 representative study sites were selected in
each, without consideration of proportional sampling or optimal allocation (e.g., see Cochran
1977). These included the following:
Yentna Reach (Cook Inlet to Little Willow Creek; RM 0.0–50.5): 13 sites
Sunshine Reach (Rustic Wilderness to Parks Highway Bridge; RM 58.1–83.5): 10 sites
Talkeetna Reach (Parks Highway Bridge to Curry; RM 83.5–120.7): 11 sites
Gold Creek Reach (Curry to Portage Creek; RM 120.7–148.8): 12 sites
Impoundment Reach (Devils Canyon to Denali Highway; RM 151–281): 8 tributaries
With few exceptions, the sites sampled for aquatic habitat studies were the same as those
sampled under resident and juvenile anadromous fish studies in 1981 and 1982. Selection of
specific sampling sites was not based upon strict statistical sampling designs. Instead, sites were
selected that were considered representative of each reach, and were based effectively on where
fish were found. This basis was carried forward in subsequent years. For example, in 1982,
habitat information was collected where spawning fish were located within the mainstem Susitna
River downstream of Devils Canyon (tributary/mainstem confluence areas and sloughs were not
sampled). Only spawning sites for chum salmon were observed in the mainstem, which led to
the identification of eight mainstem spawning locations between Lane Creek (RM 113.6) to
Devils Canyon.
Information on the distribution and abundance of juvenile and resident fish was also important to
the Aquatics Study Program. Sampling for juvenile and resident fishes from November 1980
through mid October 1981 included a wide range of sites and sampling techniques. By June of
1981, the Aquatic Studies Program had settled on 39 areas, which they termed “habitat
2 This naming convention is not being applied to the 2013/2014 studies. Rather, side sloughs will remain side
sloughs even if breached via main channel flow.
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locations,” that were the focus of sampling during the open water period (Delaney et al. 1981).
During the winter of 1980 to 1981, 29 of the habitat locations were sampled, plus an addition 48
“selected fish habitat sites” that were described as exploratory sampling. An understanding of
habitat utilization by juvenile anadromous and resident fish was developed as part of more
focused studies during 1982, 1983, and 1984. During 1982, 17 sites referred to as Designated
Fish Habitat (DFH) sites were surveyed twice monthly from June through September during the
open water season (Estes and Schmidt 1983). These sites were selected based upon four criteria
(Estes and Schmidt 1983; ADF&G 1983):
1. Areas that will be affected by changes in discharge of the mainstem Susitna.
2. Sites identified from previous studies to have significant populations of resident and
juvenile anadromous species.
3. Access to areas will not create severe logistics problems and limit the overall scope of
the studies.
4. Sites selected represent a cross-section of critical areas available to resident and juvenile
anadromous fish of the Susitna River.
Twelve of these sites were located in the Middle River (Whiskers Creek and Slough to Portage
Creek Mouth) and five were located in the Lower River (Goose Creek and Side Channel to Birch
Creek and Slough; Table 3.1-1; Figure 3.1-2).
Habitat zones were delineated within each DFH site based upon the influence of mainstem flow,
tributary flow, and water velocity (Table 3.1-2; Figure 3.1-3). Because the zones were based
upon flow characteristics, the size of the zones may have varied from survey to survey. As part
of the statistical analysis the nine zones were aggregated into Hydraulic and Water Source Zones
(Table 3.1-3). In addition to statistical tests to determine associations between fish species catch
per unit effort and aggregate hydraulic and water source zones, tests were also run to examine
correlations between catch per unit effort and habitat variables including water temperature,
turbidity, and velocity (Schmidt and Bingham (1983, Appendix E). A large number of sites (275
mainstem sites and 55 tributary and other slough sites) called Selected Fish Habitat (SFH) sites
were also sampled in 1982, but these sites were usually sampled less frequently (1 to 3 times)
and more opportunistically than DFH sites.
During 1983 and 1984, studies were focused on obtaining information needed for developing
instream flow models under the Anadromous Habitat (AH) component and sampling was
coupled with obtaining additional distribution and abundance information desired for the
Anadromous Juvenile (AJ) component (Schmidt et al. 1984, Suchanek et al. 1985). The instream
flow models include Resident Juvenile Habitat (RJHAB) and Instream Flow Incremental
Methodology (IFIM) models and Direct Input Habitat (DIHAB) models developed by Trihey and
Associates (Hilliard et al. 1985) (more information concerning these models is provided in
Section 8). As before, sites were selected based on where fish were found. During 1983, 32
sites (11 tributaries, 3 upland sloughs, 8 side slough/channel, 6 side channel, 4 side slough) were
sampled in the reach from Talkeetna to Devils Canyon for fish distribution, and 13 sites were
modeled by ADF&G with either the RJHAB (2 upland sloughs, 2 side channel/ sloughs, 1 side
slough, 1 side channel) approach or IFG approach (3 side slough/channels, 1 side slough, 3 side
channels) (see Appendix 3). The 13 modeled sites were chosen based upon observations of large
numbers of spawning salmon or concentrations of juvenile salmon during 1981 and 1982 studies
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(Dugan et al. 1984). They were also selected as being representative of the habitat types present
between the Chulitna River and Devils Canyon likely to be affected by changes in mainstem
flow from the proposed project (Dugan et al. 1984; Marshall et al. 1984).
Sampling in 1984 focused on main channel margins, side channels, side sloughs, and tributary
mouth habitats in the Middle and Lower River segments between RM 147.1 and 35.2. During
1984, crews sampled three types of study sites:
RJHAB sites (16 sites)
IFG sites (6 sites)
DIHAB sites (14 sites)
Opportunistic sites (31 sites)
Opportunistic sites were sampled only once to expand the understanding of juvenile and resident
fish distribution (Suchanek et al. 1985).
Instream flow modeling of spawning habitat was conducted for chum and sockeye salmon at
mainstem margin, side channel, upland slough, and side slough habitat types. Modeled sites
were considered to represent the range of spawning conditions for sloughs and side channels
present in the mainstem between the Chulitna River and Devils Canyon. In addition, instream
flow studies were performed to describe juvenile Chinook habitat-flow responses within
mainstem margins, side channels, side sloughs, and upland sloughs of the middle river. The
modeling studies relied effectively on the habitat classification, and manipulations thereof, for
stratifying and extrapolating model results from sampled sites to larger study reaches (Steward et
al. 1985; Ashton and Klinger-Kingsley 1985; and Klinger-Kingsley et al. 1985). The overall
approach proposed for the extrapolation process was described in Aaserude et al. (1985) and
consisted of methods for both single thread and multiple thread portions of the river (see Section
8). However, project funding was curtailed in 1985 and the approach was never implemented.
The 1983 open water studies for fish included 35 study sites (called Juvenile Anadromous
Habitat Study or JAHS sites) in the lower Middle River while the 1984 studies included 20 sites
in the Lower River (Table 3.1-4). Macro habitat types included in the study were those
described above (i.e., tributary, upland slough, side slough, and mainstem side channel).
Rationale for sites selected for study included (Dugan et al. 1984):
1. Sites where relatively large numbers of spawning adult salmon were recorded in 1982
(ADF&G 1982),
2. Sites where concentrations of rearing juvenile salmon were observed or collected in
1981 and 1982, and
3. Sites representing macrohabitat types associated with the Susitna River that are affected
by changes in mainstem flow.
In addition to the combined AH and AJ sampling efforts, studies were implemented to better
understand juvenile salmon outmigration and growth (Roth et al. 1984, Roth and Stratton 1985),
resident fish distribution and abundance (Sundet and Pechek 1985), river productivity (Wilson
1985, Nieuwenhuyse 1985), and invertebrate food sources for Chinook salmon (Hansen and
Richards 1985).
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The 1983 and 1984 JAHS sites were sampled in a systematic fashion within grids delineated at
each site (Dugan et al. 1984, Suchanek et al. 1985). As described in Dugan et al. (1984) and
depicted in Figure 3.1-4:
“Each of the study sites was divided into one or more grids. Grids were located
to keep water quality (temperature, turbidity) within the site as uniform as
possible and to encompass a variety of depth, velocity, cover, and substrate types.
Each grid consisted of a series of transects which intersected the channels of the
study sites at right angles. There were one to three cells (6 ft. in width by 30 ft. in
length = 300 sq. ft.) at every transect within the grid. An attempt was made to
confine uniform habitat within each cell. Fish were usually sampled from a
minimum of seven cells within each grid at each site.
The cells were selected to represent the complete range of habitat types available
within the grid. Fish density was estimated by electrofishing or beach seining the
entire cell, attempting to capture all fish. Catch per unit effort (CPUE) was
defined as the catch (number of fish) per cell.”
The analysis utilized the percent distribution of each salmon species among the four
macrohabitat types sampled as the evaluation metric. Analysis of variance (ANOVA) techniques
were used to discern factors affecting habitat use by the different juvenile salmon species. In
addition to site and sampling period, the factors collected in each cell following fish sampling
included mean water depth, mean water velocity, mean percent cover, water temperature, and
turbidity. Depth, velocity, and cover measures were averaged over the entire site because the
cells were not randomly distributed.
3.2. Susitna-Watana Hydroelectric Project 2013-2014 Studies:
Stratification and Study Site Selection
Review of the process and methodologies applied in selecting study and sample sites during the
1980s Su-Hydro studies provided a good foundation of information that factored directly into
development of the stratification and study site selection for the resource studies associated with
the Susitna – Watana Project. That process was described in RSP Section 8.5 and restated with
some modification in a Technical Memorandum provided to the FERC on March 1, 2013 (R2
2013b). For convenience, and for comparison with the 1980s studies, salient portions of the TM
(R2 2013b) are presented below.
3.2.1. River Stratification and Classification
As noted in Section 3.1, during the 1980s studies and in consideration of the two-dam
configuration, the Susitna River was characterized into three segments, an Upper segment that
extended above the Devils Canyon Dam site (lower dam), a Middle segment extending from the
lower dam site to the Three Rivers Confluence, and a Lower segment that extended down to
Cook Inlet (see Section 3.1). The currently proposed Susitna – Watana Dam project entails a
single dam configuration at the Watana Dam site at PRM 187.1. Therefore, although the river
was again stratified into three segments, the segment start and end locations differ from those
specified in the 1980s. In this case, the Upper River Segment represents that portion of the
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watershed above the Watana Dam site3 at PRM 187.1 (RM 184), a Middle River Segment
extending from PRM 187.1 downstream to the Three Rivers Confluence at PRM 102.4, and a
Lower River Segment extending from the Three Rivers Confluence to Cook Inlet (PRM 0)
(Figure 3.2-1),. From an instream flow perspective, the study area at issue with respect to the
Susitna-Watana Project operations and flow regulation effects consists of the Middle and Lower
River segments.
The Middle River Segment represents the section of river below the Project dam that is projected
to experience the greatest effects of flow regulation caused by Project operations. Within this
reach, the river flows from Watana Canyon into Devils Canyon, the narrowest and steepest
gradient reach on the Susitna River. The Devils Canyon constriction creates extreme hydraulic
conditions including deep plunge pools, drops, and high velocities. Downstream of Devils
Canyon, the Susitna River widens but remains essentially a single main channel with stable
islands, numerous side channels, and sloughs.
The Lower River Segment receives inflow from three other large river systems. An abrupt,
large-scale change in channel form occurs where the Chulitna and Talkeetna rivers join the
Susitna River near the town of Talkeetna in an area referred to as the Three Rivers Confluence.
The annual flow of the Chulitna River is approximately the same as the Susitna River at the
confluence, though the Chulitna contributes much more sediment than the Susitna. The
Talkeetna River also supplies substantial flow rates and sediment volumes. Farther downriver,
the Susitna River becomes notably more braided, characterized by unstable, shifting gravel bars
and shallow subchannels. The Yentna River is a large tributary to the Lower Susitna River and
supplies about 40 percent of the mean annual flow at the mouth of the Susitna River.
Contemporary geomorphic analysis of both the Middle River and Lower River segments
confirmed the distinct variations in geomorphic attributes (e.g., channel gradient, confinement,
channel planform types, and others) (see RSP Section 6.5) and resulted in the classification of
the Middle River Segment into eight geomorphic reaches and the Lower River Segment into six
geomorphic reaches (see Figures 8.5-11 and 8.5-12 of RSP Section 8.5,). These reaches were
incorporated into a hierarchical stratification system that scales from relatively broad to more
narrowly defined categories as follows:
Segment → Geomorphic Reach → Mainstem Habitat Type →
Main Channel Mesohabitat Types → Edge Habitat Types
The highest level category is termed Segment and refers to the Middle River Segment and the
Lower River Segment. The Geomorphic Reach level is next and consists of the eight reaches
(MR-1 through MR-8) for the Middle River Segment and six reaches (LR-1 through LR-6) for
the Lower River Segment (see RSP Section 6.5.4.1.2.2 and RSP Section 8.5 Table 8.5 4). The
geomorphic reach breaks were based in part on the following five factors: 1) Planform type
(single channel, island/side channel, braided); 2) Confinement (approximate extent of floodplain,
off-channel features); 3) Gradient; 4) Bed material / geology; and 5) Major river confluences.
This level is followed by Mainstem Habitat Types, which capture the same general categories
applied during the 1980s studies but include additional sub-categories to provide a more refined
delineation of habitat features (see RSP Section 8.5 Table 8.5 5). Major categories and sub-
3 The Watana Dam site was the upper dam proposed as part of the Su-Hydro Project.
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categories under this level include: 1) Main Channel Habitats consisting of Main Channel, Split
Main Channel, Braided Main Channel, Side Channel; 2) Off-channel Habitats that include Side
Slough, Upland Slough, Backwater and Beaver Complexes; and 3) Tributary Habitats that
consist of the segment of the tributary influenced by mainstem flow. The next level in the
hierarchy is Main Channel and Tributary Mesohabitats, which classifies habitats into categories
of Cascades, Riffle, Pool, Run, and Glide. The mesohabitat level of classification is currently
limited to the main channel and tributary mouths for which the ability to delineate these features
is possible via aerial imagery and videography. Mesohabitat mapping in side channel and slough
habitat types will require ground surveys, planned to begin in 2013. The last level in the
classification is Edge Habitat and is intended to provide an estimate of the length of shoreline in
contact with water within each habitat unit. The amount of edge habitat within a given habitat
unit will provide an index of habitat complexity, i.e., more complex areas that consist of islands,
side channels, etc. will contain more edge habitat than uniform, single channel areas.
Overall, the goal of the stratification step for the 2013-2014 studies was to define
segments/reaches with effectively similar characteristics where, ideally, repeated replicate
sampling would result in parameter estimates with similar statistical distributions. The
stratification/classification system described above was designed to provide sufficient
partitioning of sources of variation that can be evaluated through focused study efforts that target
each of the habitat types, and from which inferences concerning habitat–flow responses in
unmeasured sites can ultimately be drawn.
3.3. Selection of Study Areas/Study Sites
In general (as noted by Bovee 1982), there are three characteristic approaches to instream flow
studies that pertain to site selection that were considered for application for the Susitna-Watana
Project. These included representative sites/areas, critical sites/areas, and randomly selected
sites/areas.
3.3.1. Representative Sites
Representative sites are those where professional judgment or numerically and/or qualitatively
derived criteria are relied on to select one or more sites/areas that are considered representative
of the stratum or larger river. Representative sites typically contain all habitat types of
importance. In general, the representative site approach can be readily applied to simple, single
thread channel reaches, where the attributes that are measured are extrapolated linearly based on
stream length or area. In this case, the goal of stratification will be to identify river segments that
are relatively homogenous in terms of mesohabitat mixes, and the methods used for stratification
tend to be classification-based. This approach typically requires completing some form of
mapping up front, and using the results to select sites that encompass the range of habitat
conditions desired. The results of such habitat mapping were not available during the initial
study site/area selection, but since then, the results of the habitat mapping have been completed
and analyzed and are reported in R2 2013b.
3.3.2. Critical Sites
Critical sites are those where available knowledge indicates that either (i) a sizable fraction of the
target fish population relies on that location, (ii) a particular habitat type(s) is (are) highly
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important biologically, or (iii) where a particular habitat type is well known to be influenced by
flow changes in a characteristic way. For example, in the case of the Susitna River, historical
fish studies repeatedly showed the importance of certain side slough, upland slough, and side
channel areas for spawning and juvenile rearing. Critical sites or areas are typically selected
assuming that potential Project effects to other areas are secondary in terms of implications to
fish population structure, health, and size. This assumption can only really be tested if other sites
are identified that are similar looking but were not deemed critical, and sampling is performed on
those sites as well to confirm the critical nature of the sites that were identified as such.
3.3.3. Randomly Located Sites
Randomly located sites are those sites, areas, or measurement locations selected randomly from
each defined stratum or habitat type, and replicate sites or cross-sections are sampled to estimate
variance (e.g., Williams 1996; Payne et al. 2004). Site selection based on random sampling
tends to involve statistical multivariate grouping or stratification approaches, such as cluster
analysis or ordination techniques. The approach is the least subject to potential for bias, because
it relies on distinct rules and algorithms. However, the approach becomes increasingly difficult
to apply in site selection when the sites become more complex, such as is the case on the Susitna
River. In addition, the number of sites will be contingent on the variability within the universal
data set: the greater the number of clusters, the greater the potential number of sites. Strict
random sampling is therefore not likely applicable for evaluating off-channel habitats and
sloughs where the morphology of multiple channels varies substantially and in complex ways
within and across sites.
3.3.4. Focus Areas and Study Sites – Middle River Segment
The concept of “intensive study areas” was introduced during a September Technical Workgroup
Meeting (TWG) and discussed relative to sampling the Middle River Segment. This concept
evolved from the realization that a prerequisite to determining the effects of Project development
and operations on the Susitna River is the need to first develop an understanding of the basic
physical, chemical and ecological processes of the river, their interrelationships, and their
relationships with flow. Two general paths of investigation were considered, 1) process and
resource specific and 2) process and resource interrelated. Under the first, process and resource
specific, studies would focus on determining relationships of flow with specific resource areas
(e.g., water quality, habitat, ice, groundwater) and at specific locations of the river without
considering interdependencies of other resource areas at different locations. Under the second,
process and resource interrelated, studies would be concentrated at specific locations of the river
that would be investigated across resource disciplines with the goal of providing an overall
understanding of interrelationships of river flow dynamics on the physical, chemical, and
biological factors that influence fish habitat.
Because the flow dynamics of the Susitna River are complex, it was reasoned that concentrating
study efforts across resource disciplines within specific locations would provide the best
opportunity for understanding flow interactions and evaluating potential Project effects and
therefore major emphasis was placed on selecting those areas, which were termed Focus Areas
(FA). However, it was also reasoned that there will be a need to collect information and data
from other locations to meet specific resource objectives. As a result, the study site/area
selection process presented in the RSP (Section 8.5) pertaining to the Middle River Segment
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represented a combination of both approaches and resulted in the identification of ten FAs that
are described in Table 3.3-1 and displayed in Figures 3.3-1 to 3.3-11.
Composition wise, the FAs contain combinations of different habitat types and features as
characterized according to the hierarchical classification system noted above. The FA concept
represents a combination of all three of the study site selection methods described above,
inasmuch as (1) the areas would contain habitat types representative of other areas; (2) the areas
would include certain habitat types repeatedly used by fish and therefore can be considered
“critical areas,” and (3) sampling of certain habitat features or mesohabitat types within the areas
would be best approached via random sampling. A comparative analysis of the habitat types
present within each of the FAs compared to habitat types outside of FAs was completed and
indicated that the ten FAs are generally representative of habitat types found in other portions of
the river (see Section 3.1.1 of R2 2013b). Analysis of the FAs from the riparian perspective
confirmed the representativeness of eight of the areas for analysis, with a further peer review
resulting in selection of five FAs for final riparian investigation (see Section 3.1.2 of R2 2013).
In addition to the FAs in the Middle River, a number of other study sites have been identified
that are specific to the goals and objectives of different resource investigations (see Fisheries
(RSP Section 9.6, 9.8, and 9.9), Groundwater (RSP Section 7.5), Geomorphology (RSP Section
6.0), Ice Processes (RSP Section 7.6), and Water Quality (RSP Section 5.0).
3.3.5. Study Sites – Lower River Segment
Application of an FA approach to sampling the Lower River Segment was deemed unfeasible
given the channel complexity, size, and inherent changing nature of the channel morphology. As
a result, study areas were tentatively identified by AEA’s inter-disciplinary team including
representatives from geomorphology, instream flow-fish, instream flow-riparian, and
groundwater. One area was selected in each of the geomorphic reaches LR-1 and LR-2 to
describe the mix of thalweg channel, major subchannels, alluvial island complexes, side channels
and sloughs observed in aerial photos of the Lower River Segment channel. The area around
Trapper Creek near PRM 94.5 was selected as representative of the habitat types in LR-1 (Figure
3.3-12), and the area around Caswell Creek near PRM 67 was selected as representative of
habitat types in LR-2 (Figure 3.3-13). Study sites proposed for fish sampling, groundwater, and
riparian studies are depicted in Figure 3.3-14 in 2013. The Susitna-Watana studies have been
founded around an adaptive management framework such that the results from the 2013 studies
for the Lower Susitna River Segment will provide a basis for assessing the need to perform
further data collection and analysis in 2014.
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4. TECHNICAL MEMORANDUM – SUMMARY OF FISH
DISTRIBUTION AND ABUNDANCE STUDIES CONDUCTED
DURING THE 1980S SU-HYDRO PROJECT
One of the primary objectives of the aquatic investigations completed for the 1980s Su-Hydro
Project was to determine the distribution and abundance of both anadromous and resident fish
species in the Susitna River. This information was considered essential for understanding how
project operations may affect different species over space and time. As a result, a substantial
effort was expended over a five year period (1981- 1985) conducting studies concerning the
distribution and abundance of fish.
This TM summarizes salient information concerning those studies and includes a discussion of
methods used, study sites sampled and general results on a species basis. The TM is
complementary to the fish data synthesis document prepared by R2 (2013a) which should be
referred to for more detailed information on the 1980s Su-Hydro fish studies.
4.1. Summary of Methods Used
Information on the distribution and abundance of anadromous and resident fish species in the
Susitna River was collected using a variety of methods deployed at selected locations from the
mouth of the river to the Oshetna River (RM 226.9) and within selected tributaries. Escapement
and distribution of adult salmon during the 1980s Aquatic Studies Program was primarily based
upon three sampling techniques:
Fishwheels and sonar
Spawning surveys
Radio tracking
Floy spaghetti tags or Petersen disc tags were used to study fish movements and to estimate
escapement using Peterson estimation techniques. Adult periodicity information is primarily
available from fishwheels and Bendix sonar stationed at a number of locations in the mainstem
Susitna River and in the Yentna River (Table 4.1-1). Stations were generally deployed in early-
to mid-June and fished through early- to mid-August. Spawning surveys occurred annually by
foot, raft, airplane, or helicopter. Radio tracking of adult Chinook (Oncorhynchus tshawytscha),
coho (O. kisutch), and chum salmon (O. keta) occurred in 1981 and 1982 and was used to
identify spawning and holding locations and better understand migration rates (ADF&G 1981,
ADF&G 1982). The number of salmon tracked within a species and year was 18 or fewer fish
(Table 4.1-2). Length information was obtained from a subsample of salmon captured at the
fishwheels and scales removed to determine the age structure of returning adults and the age at
ocean entry.
Sampling for juvenile salmon and resident fish included a wide range of sampling techniques
that included beach seine, dip net, boat and backpack electrofishing, drift gill nets, set gill nets,
minnow traps, trot lines, fyke/hoop nets, and hook and line. Effort expended by each gear type
varied from year to year and by sampling site. Beach seines, minnow traps, trotlines, and boat
and backpack electrofishing were the most commonly used gear for most sampling sites. Hook
and line was the primary method for capturing Arctic grayling (Thymallus arcticus) in
tributaries of the Upper Susitna River. Similar to adult salmon, captured resident fish were
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commonly tagged with Floy spaghetti or anchor tags to determine fish movements, growth, and
estimation of population size. During 1984 and the winter of 1985-1986 juvenile Chinook and
coho salmon were marked with cold brands or tagged with coded wire tags (CWT) to study
tributary outmigration, overwintering habitat use, and population estimation (Schmidt et al.
1985, Stratton 1986). Radio tracking occurred on rainbow trout (O. mykiss), burbot (Lota lota)
and Arctic grayling to identify spawning areas and movement patterns (Table 4.1-2). Fish
sampling during winter primarily used trotlines and minnow traps, with occasional use of
backpack electrofishing, gill nets, and fyke nets in open leads. Length information was obtained
from a subsample of fish captured and scales removed to determine age structure.
Outmigration timing of juvenile salmon was monitored each year from 1982 to 1985 using
incline plane traps (Schmidt et al. 1983, Roth et al. 1984, Roth and Stratton 1985, Roth et al.
1986). Traps were deployed shortly after ice-off (mid-May to mid-June) and fished until early-
to mid-October (Table 4.1-3). Locations on the mainstem Susitna River included fixed traps
near Flathorn Station (one or two traps at RM 22.4 and 24.6) and at Talkeetna Station (two traps
at RM 103) and deployment of a mobile trap that sampled along a cross sectional transect at RM
25.4 near Flathorn.
4.2. Study Site Locations
In general, resident and juvenile (RJ) studies were broad-based during 1981 and 1982 with the
widest geographic scale and sampling methods. Sampling in the Susitna River upstream of
Devils Canyon (i.e., Reach 1) only occurred during 1981 and 1982, while sampling occurred
downstream of Devils Canyon during 1981 through 1985. As the Aquatic Studies Program
progressed, studies became more focused on acquiring specific information needs for habitat
modeling and acquisition of specific biological data. In addition, the results of 1981 and 1982
sampling led to conclusions regarding fish distribution and hypotheses about habitat utilization
that led to more intensive sampling at fewer sites with known fish use and a reliance on fewer
sampling techniques that had demonstrated effective fish capture success within habitats and
field conditions found in the river.
Sampling for juvenile and resident fish from November 1980 through mid October 1981
included a wide range of sites. By June of 1981, the Aquatic Studies Program had settled on 39
areas in the Lower and lower Middle Susitna River, which they termed “habitat locations”, that
were the focus of sampling during the open water period (Delaney et al. 1981a, 1981b). During
the winter of 1980 to 1981, 29 of the habitat locations were sampled, plus an addition 48
“selected fish habitat sites” that were described as exploratory sampling. An understanding of
habitat utilization by juvenile anadromous and resident fish was developed as part of more
focused studies during 1982, 1983, and 1984. During 1982, 17 sites referred to as Designated
Fish Habitat (DFH) sites were surveyed twice monthly from June through September during the
open water season (Estes and Schmidt 1983). Twelve sites were located in the Middle River
(Whiskers Creek and Slough to Portage Creek Mouth) and five were located in the Lower River
(Goose Creek and Side Channel to Birch Creek and Slough).
During 1983 and 1984, studies were focused on obtaining information needed for developing
instream flow models under the AH component and sampling was coupled with obtaining
additional distribution and abundance information desired for the AJ component (Schmidt et al.
1984, Suchanek et al. 1985). The 1983 open water studies included 35 study sites (called
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Juvenile Anadromous Habitat Study or JAHS sites) in the lower Middle River while the 1984
studies included 20 sites in the Lower River.
4.2.1. Upper River Study Sites
Fish distribution abundance surveys were conducted in the Upper Susitna River during 1981 and
1982. In addition, aerial Chinook salmon spawning surveys were conducted by helicopter in
selected tributaries and tributary mouths each year from 1981 to 1985. During 1981 surveys
were conducted in five tributaries of the Upper Susitna River: Watana Creek (RM 190.4), Kosina
Creek (RM 202.4), Jay Creek (RM 203.9), Goose Creek (RM 224.9), and the Oshetna River
(Delaney et al. 1981c). Each stream was surveyed in up to five segments (0 to 500 ft, 1000 to
1500 ft, 2000 to 2500 ft, 2500 to 3000 ft, 4000 to 4500ft). The lower segments also included
sampling in the Clearwater areas of the mainstem influenced by the tributary outflow. Gillnet
and hook and line surveys also occurred at Sally Lake, which drains to Watana Creek, and hook
and line surveys occurred in Deadman Lake. Delaney et al. (1981) indicated that Arctic grayling
were captured in the Tyone River (RM 346.6), but details regarding the location, gear, or
numbers captured were not reported.
During 1982, tributary surveys in the Upper Susitna River were focused on understanding the
distribution and abundance of Arctic grayling in areas that would be inundated by the proposed
reservoir and surveys were conducted over greater distances: Watana Creek (TRM 4.0 to 6.0;
East Fork TRM 8.5 to 9.8, West Fork TRM 8.5 to 10.6), Kosina Creek (TRM 0.0 to 4.5), Jay
Creek (TRM 0.0 to 3.8), Goose Creek (TRM 0.0 to 1.2), and the Oshetna River (TRM 0.0 to 2.2;
Sautner and Stratton 1983).
Mainstem sampling other than the tributary mouths, only occurred during 1982 at seven
mainstem slough areas: Site No. 1 (RM 191.5), Site No. 2 (RM 191.5), Watana Creek Slough
(RM 194.1), Site No. 3 (RM 197.8), Site No. 3A (RM 201.6), Site No, 4 (RM 201.2), and Site
No. 5 (Lower Jay Creek Slough, RM 208.1; Sautner and Stratton 1983). In addition, Sally Lake
was surveyed during 1982.
4.2.2. Middle River Study Sites
During 1981 and 1982, the Middle Susitna River segment upstream of the proposed Devils
Canyon Dam at RM 152 (upper Middle Susitna River) was considered part of the Upper River
and reported along with other Upper Susitna River tributaries in Delaney et al. (1981) and
Sautner and Stratton (1983). Tributaries surveyed by Delaney et al. (1981) during 1981 included
up to five sections in Fog Creek (RM 173.9), Tsusena Creek (RM 178.9), and Deadman Creek
(RM 183.4). During 1982 survey distances were Fog Creek TRM 0.0 to 1.3, Tsusena Creek
TRM 0.0 to 0.4, and Deadman Creek TRM 0.0 to 2.7. In addition, Cheechako Creek (RM
152.4), Chinook Creek (RM 157.0), and Devil Creek (RM 161.4) were sampled during 1982.
No mainstem sites were surveyed in the upper Middle Susitna River during 1981.
Sampling occurred in the lower Middle Susitna River from the Three Rivers Confluence to the
proposed Devils Canyon Dam during each of the years 1981 to 1985 to discern the distribution
and relative abundance of adult anadromous spawning fish (AA studies) and resident and
juvenile anadromous fish (RJ studies). Spawning surveys were conducted at Chinook salmon
index streams from mid-July through mid-August (ADF&G 1981, ADF&G 1983b, Barrett et al.
1984, Barrett et al. 1985, Thompson 1986). For other salmon species all known slough, side
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channel, and tributary streams known to be used by adult salmon in the Middle River
downstream of Devils Canyon on a weekly basis, generally started in late July to early August
and ended in mid-October.
The RJ studies component sampled 17 habitat locations during 1981, 13 DFH sites during 1982,
35 JAHS sites during 1983, 24 sites during 1984, and 20 sites in 1985 (Table 4.2-1). Many of
the sites were sampled during 1984 and 1985 primarily to mark (cold brand) or tag (coded wire
tag) juvenile Chinook or coho salmon that could potentially be recaptured at incline plane traps
located farther downstream, or were specifically sampled for resident fish. In addition to the
habitat locations and DFH sites sampled in 1981 and 1982, respectively, a relatively large
number of sites called selected fish habitat (SFH) sites were sampled opportunistically 3 or fewer
times over the open water season. During 1981 the SFH sites were sampled primarily by
minnow trap and trotline (Delaney et al. 1981c) while during 1982 these sites were primarily
sampled using boat electrofishing gear (Figure 4.2-1).
During 1984 six lakes with outlets that drain to the lower Middle River Segment were sampled to
determine if rainbow trout were present and whether they use the mainstem Susitna River
(Sundet and Pechek 1985). These included four lakes that drain into Fourth of July Creek,
Miami Lake that drains into the Indian River at TRM 4.5, and one unnamed lake that drains into
Portage Creek at TRM 2.3.
4.2.3. Lower River Study Sites
A relatively large number of habitat location sites (22) were sampled in the Lower Susitna River
for juvenile and resident fish during 1981 (Table 4.2-2; Delaney et al. 1981a, b). Sampling effort
in the Lower Susitna River was somewhat lower in 1982 compared to 1981, with 12 DFH sites
sampled twice per month in the open water period from RM 74.8 (Goose 2 Side Channel) to RM
91.6 (Trapper Creek Side Channel; Schmidt et al. (1983). However, similar to the Middle
Susitna River numerous SFH sites were sampled usually one to three times over the open water
period, which did contribute to the understanding of fish distribution (Figure 4.2-1). During
1983 resident and juvenile salmon sampling was focused on the Middle Susitna River and no
sites were sampled in the Lower Susitna River. Sampling occurred at 20 JAHS sites in the
Lower Susitna River during 1984 and no sites were sampled during 1985.
Sampling specifically for eulachon and Bering cisco occurred during 1982 and 1983 (ADF&G
1983b, Barrett et al. 1984, Vincent-Lang and Queral (1984). From May 16 through June 9,
1981, ADF&G (1983) used set gillnets at two sites in Susitna River estuary between RM 4.0 and
RM 4.5 and dip nets and boat electrofishing gear between RM 4.5 and the Kashwitna River
confluence at RM 61. From May 10 through June 9, 1983, set gillnets were deployed at three
sites between RM 2.3 to RM 4.5 (Barrett et al. 1984). Similar to 1982, dipnets and electrofishing
occurred between RM 4.5 and RM 60 during 1983. The gillnet sampling was used to better
understand run timing while the dipnet and electrofishing was used to identify spawning areas
and better understand the extent of upstream migration by spawning eulachon. Vincent-Lang
and Queral (1984) selected 20 sites between RM 20.0 and RM 36.5 identified by ADF&G (1983)
as eulachon spawning locations for characterizing spawning habitat between May 23 and May
26, 1983. Measurements included depth, velocity, substrate composition, and water quality.
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4.3. Results
4.3.1. Upper River Studies
Because Susitna-Watana Project flow related effects will not occur above the Watana Dam, the
contemporary instream flow studies (IFS) proposed for 2013-2014 will not be modeling or
sampling in the Upper River (see RSP 8.5). Nevertheless, the Upper Susitna River may be a
source of fish that move downstream and use habitat potentially affected by the proposed
Project. Consequently, an understanding of the fish populations present in the Upper Susitna
River is important.
The only anadromous fish known to pass all three of the riffle barriers within Devils Canyon is
Chinook salmon. The Upper Susitna River fish community has relatively low diversity
compared to the Susitna River downstream of Devils Canyon (Table 4.3-1). The Upper Susitna
River is dominated by Arctic grayling in tributary streams (Delaney et al. 1981c, Sautner and
Stratton 1983). The resident fish community also includes burbot, Dolly Varden (Salvelinus
malma), round whitefish (Prosopium cylindraceum), humpback whitefish (Coregonus
pidschian), longnose sucker (Catostomus catostomus), and sculpin (Cottus spp.). However, their
distribution and abundance in the mainstem Susitna River is poorly understood because few
surveys have been conducted. Lake trout are also present in some of the lakes draining to the
Upper Susitna River, but relatively few of the lakes have been surveyed (e.g., Sally Lake and
Deadman Lake). During 1981 and 1982 eight tributaries and tributary mouths were surveyed, as
well as Sally Lake and Deadman Lake. The 1982 sampling in tributaries was focused primarily
on developing abundance estimates for Arctic grayling using mark recapture methods and
angling.
4.3.1.1. Chinook Salmon
The distribution of Chinook salmon (O. tshawytscha) in the Upper Susitna River is uncertain
because relatively few surveys have occurred and their abundance is low. However, Chinook
salmon appear to be present to at least the Oshetna River during some years (Figure 4.3-1).
Surveys conducted by Buckwalter (2011) during 2003 and 2011 resulted in the collection of
Chinook juveniles in the Oshetna River (2003 only) and adults (2011) and juveniles (2003) in
Kosina Creek (Table 4.3-2Table 4.3-). Surveys conducted during 2012 by helicopter resulted in
the observation of 16 adult Chinook salmon in Kosina Creek (HDR 2013).
4.3.1.2. Arctic Grayling
Arctic grayling (Thymallus arcticus) were captured in all of the tributaries sampled (Figure 4.3-
2). Delaney et al. (1981c) reported the capture of 3,313 Arctic grayling during 1981, and Sautner
and Stratton (1983) reported the capture of 4,367 Arctic grayling during 1982. Hook and line
was a very successful capture method in tributary streams during 1981 and 1982 with a median
catch rate of 6.0 fish per hour and a maximum rate of 23.2 fish per hour.
During 1981, catch rates by anglers were highest for Kosina and Jay creeks (Figure 4.3-2).
Angler catch rates increased from May (6.1 fish per hour) to July (8.1 fish per hour) and then
declined in August (4.5 fish per hour) and September (4.0 fish per hour). A Chi-square analysis
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on the number of fish captured by angling indicated there were significant differences in catch
between the tributaries.
For many sites and sampling periods, hook and line catch rates were somewhat higher in 1982
compared to 1981. During 1982, hook and line catch rates were highest for the Oshetna River
(11.1 fish per hour) and Kosina Creek (10.4 fish per hour; Figure 4.3-2). Catch rates were
highest in July (12.8 fish per hour) and August (13.4 fish per hour).
Observations of spent Arctic grayling with frayed fins during late May and early June suggested
that most spawning had already been completed; however two ripe males were collected on May
22 (Delaney et al. 1981c). Based upon this information and experience from other areas,
Delaney et al. (1981c) suggested that Arctic grayling spawning likely occurs during late-April to
mid-May. Arctic grayling fry and Age 1+ were observed in the slough near Jay Creek. Fry were
20 to 22 mm in June, 24 to 45 mm in July, and 47 to 60 mm in September. Age 1 Arctic
grayling were 54 mm in May, 75 to 95 mm in June, and 84 to 98 mm in July.
In 1981, Floy tags were attached to 2,511 Arctic grayling and 268 tagged fish were recaptured
(Delaney et al. 1981c). In 1982, 3,560 Arctic grayling were tagged and 350 tagged fish were
recaptured (Stratton 1983). Population sizes were estimated using the Schnabel method from the
mark-recapture data with a total upper Middle and Upper Susitna River estimate of 10,279 fish
with a 95 percent confidence interval of 9,194 to 11,654 fish (Table 4.3-3Table 4.3-). Total
Arctic grayling population size during 1982 was 16,346 fish (Sautner and Stratton (1983). In the
Upper Susitna River, Arctic grayling abundance was highest in Kosina Creek and lowest in
Goose Creek. Tagged Arctic grayling moved around considerably (Delaney et al. 1981c, Sautner
and Stratton 1983). In 1981, 243 fish were recaptured within the same tributary in which they
were tagged. Of these fish, 50 moved up to 2 miles downstream and 69 fish moved up to 12
miles upstream. Approximately half (124 fish) of the recaptured tagged fish remained at the
tagging location, and nine percent were recaptured in a tributary or tributary mouth different
from the tagging location. The longest movement was 34.5 miles from Goose Creek to Watana
Creek. During 1982, Arctic grayling tagged in tributaries made movements of up to 30.2 miles,
and similar to 1981, a substantial proportion of the recaptured fish (12.0 percent) were recaptured
in a different stream than tagged (Sautner and Stratton 1983).
In 1982, relatively few Arctic grayling were captured at mainstem sites (Sautner and Stratton
1983). Among the seven mainstem slough sites that were sampled, only 21 Arctic grayling and,
and all were captured at the Watana Creek Slough. Sampling in Sally Lake resulted in the
capture of 42 Arctic grayling.
4.3.1.3. Dolly Varden
Dolly Varden (Salvelinus malma) were present in the Upper Susitna River (Delaney et al. 1981c,
Sautner and Stratton 1983), but relatively uncommon compared to Arctic grayling. No Dolly
Varden were captured in the Upper Susitna River during 1981. Sautner and Stratton (1983)
captured a total 16 Dolly Varden at five of the upper Middle and Upper tributaries sampled
during 1982 and three of the tributaries, Watana, Jay creeks, and upper Deadman creeks, were in
the Upper Susitna River. All of the Dolly Varden captured during 1982 in the Upper Susitna
River were small (120 to 205 mm) and considered stunted.
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4.3.1.4. Burbot
Burbot (Lota lota) were present throughout the mainstem Upper Susitna River to at least the
Oshetna River (Delaney et al. 1981c, Sautner and Stratton 1983). Delaney et al. (1981) captured
88 burbot immediately upstream or downstream from the mouth of tributaries. During 1981,
CPUE was not reported by each period and site. However, the overall monthly CPUE ran ged
from 0.5 burbot per trotline-day in June to 1.0 burbot per trotline-day in September. Most burbot
were captured near the mouth of Jay Creek (32 fish) and Watana Creek (24 fish) during 1981
(Figure 4.3-3). Sautner and Stratton (1983) sampled at seven locations within the mainstem
during 1982 and captured 135 burbot by trotline. Overall monthly CPUE ranged from 0.6 (July
and September) to 0.8 (June) fish per trotline-day. For individual sites and periods, CPUE
ranged from zero (Mainstem Site 2 in September) to 3.5 fish per trotline-day (Watana Creek
mouth in May; Figure 4.3-3). Burbot appeared to move little within the Upper Susitna River, or
they may have returned to feeding territories. Floy tags were attached to 23 and 69 burbot in
1981 and 1982, respectively. Four of the burbot tagged during 1981 and three of burbot tagged
during 1982 were recaptured during 1982 at the location of tagging (Sautner and Stratton (1983).
Based upon observation of spent burbot and observations by anglers in Paxson Lake, Delaney et
al. (1981c) suggested that burbot probably spawned during March in the Upper Susitna River.
4.3.1.5. Round Whitefish
Round whitefish (Prosopium cylindraceum) were present in the Upper Susitna River (Delaney et
al. 1981c, Sautner and Stratton 1983). Delaney et al. (1981) captured a total of 80 round
whitefish immediately upstream or downstream of tributary mouths. Gillnets were effective at
capturing adult round whitefish (33 fish), and beach seining and electrofishing captured 47
juvenile round whitefish at the mouth of Jay Creek. Jay and Kosina creeks accounted for 39.4
and 27.3 percent of the adult round fish captured. None of the 17 floy-tagged round whitefish
were recaptured. During the studies by Sautner and Stratton (1983), five adult round whitefish
were captured at the Watana Creek Slough during July and August and in prespawning
condition.
4.3.1.6. Humpback Whitefish
Humpback whitefish (Coregonus pidschian) were present in the Upper Susitna River in low
numbers. During 1981, one humpback whitefish (347 mm in length) was captured at the mouth
of Kosina Creek (Delaney et al. 1981c), and in 1982, a single humpback whitefish was captured
at RM 208.1 (Sautner and Stratton (1983). Delaney et al. 1981c also reported that humpback
whitefish were present in lakes Susitna and Louise. These lakes are headwater lakes to the
Tyrone River, which enters the Susitna River near RM 246.5.
4.3.1.7. Longnose Sucker
Longnose suckers (Catostomus catostomus) were present throughout the mainstem Upper
Susitna River to at least the Oshetna River (Delaney et al. 1981c, Sautner and Stratton 1983).
Delaney et al. (1981) captured 168 longnose suckers immediately upstream or downstream from
the mouth of all surveyed tributaries except Fog and Tsusena creeks. Gillnets were effective at
capturing adult round whitefish (144 fish). Beach seines, electrofishing, and minnow traps
captured 24 juvenile longnose suckers. The Watana Creek and Jay Creek sites accounted for
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52.1 and 19.4 percent of the adult longnose suckers captured. However, catch rates were highest
in Watana Creek (12.5 fish per net-day) and the Oshetna River (4.0 fish per net-day).
During 1982, longnose suckers were captured by gillnets at four of the seven mainstem slough
sites (Sautner and Stratton 1983). Similar to 1981, the highest catch occurred near Watana Creek
(80.3 percent of all captured suckers). The highest catch observed was in July, when 21
longnose suckers were captured near the mouth of Watana Creek. Longnose suckers were in
spawning condition in May and early-June, but all were spent in late-June.
Tags were attached to 97 and 50 longnose suckers in 1981 and 1982, respectively (Sautner and
Stratton 1983). One of the fish tagged in 1981 was recaptured during 1981, and two were
recaptured in 1982. Two fish tagged in 1982 were subsequently recaptured. All recaptures
occurred at the tagging location.
4.3.1.8. Sculpin
In 1981, slimy sculpin (Cottus congnatus) were captured in minnow traps within all tributaries
sampled in the Upper Susitna River except Jay Creek (Delaney et al. 1981c). Catch rates were
highest in Fog Creek (8 per trap-day), Tsusena Creek (9 per trap-day), and the Oshetna River (10
per trap-day). Length of captured sculpins ranged from 37 to 95 mm.
4.3.1.9. Lake Trout
Sampling for lake trout (Salvelinus namaycush) occurred in Sally Lake in 1981 and 1982 and in
Deadman Lake in 1981 (Delaney et al. 1981c, Sautner and Stratton 1983). Sally Lake is a 63
acre lake with a maximum depth of 27 feet and mean depth of 11.6 feet (Sautner and Stratton
1983). The southern end of the lake is shallow (average depth of about 4 feet) and has
substantial aquatic vegetation.
In 1981, sampling in Sally Lake was primarily by gillnet with some angling, and only angling
was attempted at Deadman Lake. Lake trout were captured in both Sally Lake (32 fish, 2 by
angling) and Deadman Lake (3 fish, all by angling). Lake trout in Sally Lake were captured in
less than 6 feet of water and within 100 feet of shore. The length of lake trout in Sally Lake
ranged from 305 to 508 mm with a mean of 410 mm. Most scales removed from Lake Trout
were unreadable. Consequently, no age information was obtained. In 1982, sampling in Sally
Lake resulted in the capture of 32 lake trout (Sautner and Stratton 1983), and fish sizes ranged
from 260 to 490 mm with an average length of 419 mm.
4.3.2. Middle River Studies
4.3.2.1. Upper Middle Susitna River
The fish community in the upper Middle Susitna River was found to be similar to the Upper
Susitna River (Table 4.3-1Table 4.3-). The distribution of Chinook salmon in the upper Middle
Susitna River is uncertain because relatively few surveys have occurred and their abundance is
low. Aerial surveys conducted from 1982 to 1985 were the first to document passage of
Chinook salmon through Devils Canyon and spawning within, or near the mouth of, several
tributaries in the upper Middle Susitna River including Cheechako Creek, Chinook Creek, Devil
Creek, and Fog Creek (ADF&G 1983c, Barrett et al. 1984, Barrett et al. 1985, Thompson et al.
1986; Table 4.3-4). Surveys conducted by Buckwalter (2011) during 2003 and 2011 resulted in
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the observations of Chinook adults in Fog Creek (2003 only) and collection of juveniles during
2003 and 2011. Juvenile Chinook salmon were also collected in Tsusena Creek during 2003
(Table 4.3-2).
4.3.2.1.1. Arctic Grayling
Arctic grayling were captured in Fog Creek and Tsusena Creek in both 1981 and 1982 (Delaney
et al. 1981c, Sautner and Stratton (1983). Mark-recapture population estimates suggested
substantially more Arctic grayling were present in Tsusena Creek (1,000 fish) compared to Fog
Creek (176 fish) during 1981 (Table 4.3-3). Insufficient marks and/or recaptures occurred
during 1982 to develop estimates in Fog and Tsusena creeks (Sautner and Stratton 1983).
Average catch rates were 6.1 fish per angler-hour in Tsusena Creek and 0.4 fish per angler-hour
in Fog Creek during 1982. Sautner and Stratton (1983) indicated that Arctic grayling were
captured in Cheechako and Devil creeks during 1982, but catch rates were not reported. Arctic
grayling were not captured in Chinook Creek.
4.3.2.1.2. Dolly Varden
Dolly Varden were present in the Upper Susitna River (Delaney et al. 1981c, Sautner and
Stratton 1983), but relatively uncommon compared to Arctic grayling. Delaney et al. (1981)
captured one Dolly Varden (235 mm length) at the mouth of Fog Creek. Sautner and Stratton
(1983) captured a total of 16 Dolly Varden at five of the tributaries sampled during 1982 and two
of them, Cheechako and Devil, were in the upper Middle Susitna River. All of the Dolly Varden
captured during 1982 in the Upper Susitna River were small (120 to 205 mm) and considered
stunted.
4.3.2.1.3. Burbot
Burbot were captured by trotline near the mouth of Fog Creek during May (2 fish) and Tsusena
Creek (2 fish during June 1981 (Delaney et al. 1981c). Round whitefish (3 fish over 4 days of
effort) were captured near the mouth of Tsusena Creek by gillnet during 1981, but none were
captured near of the mouths of Fog Creek and Deadman Creek with 3 or 4 gillnet-days of effort,
respectively (Delaney et al. 1981c). Capture of longnose sucker was also low during 1981, with
3 captured near the mouth of Deadman Creek and none captured near Fog and Tsusena creeks.
Sculpin were capture in all tributaries sample during 1981 in the upper Middle Susitna River.
No sampling occurred in the mainstem of the upper Middle Susitna River during 1982 (Sautner
and Stratton 1983).
4.3.2.2. Lower Middle River
The lower Middle River (from Devils Canyon downstream to Three Rivers Confluence) has a
relatively diverse community of anadromous and resident fish species compared to the river
upstream of Devils Canyon (Table 4.3-1). In addition to the seven fish species found upstream
of Devils Canyon, there are four more anadromous salmon species, rainbow trout, three-spine
stickleback (Gasterosteus aculeatus), and Arctic lamprey (Lethenteron japonicum) present in the
lower Middle River.
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4.3.2.2.1. Chinook Salmon
Chinook salmon are one of the most important sport fish in the Susitna River drainage and
present in most of the larger tributary streams of the lower Middle River (Figure 4.3-1). Chinook
salmon spawn exclusively in tributary streams (Thompson et al. 1986, Barrett 1985, Barrett
1984, Barrett 1983; Figure 4.3-4). Consequently, the mainstem Susitna River primarily provides
a migration corridor and holding habitat for adult Chinook salmon. Apportionment of Chinook
salmon among the major Susitna River subbasins based on peak spawning surveys has been
somewhat confounded by inconsistent surveys, in part because poor visibility and partly due to
annual differences in surveying priorities. Nevertheless, major patterns in the distribution of
Chinook salmon spawning during the late 1970s and early 1980s are discernible based upon data
summarized in Jennings (1985). Within the Middle River, Portage Creek and Indian River
account for nearly all Chinook salmon spawning (Figure 4.3-5). These two tributaries in
combination with other Middle River tributaries typically account for about 5 percent of the
Chinook salmon spawning in the Susitna River. Fourth of July Creek and Whiskers Creek
account for minor amounts of spawning, generally with no more than about 2.5 percent of the
spawning in the Middle River (Figure 4.3-6).
Of the five salmon species returning to the Susitna River, Chinook salmon account for the fewest
number of fish but have been the most important sport fish (Jennings 1985). Long term
escapement trend data from 1974 to 2009 is available for a number of index streams in the
Susitna River Basin monitored by ADF&G, but between stream comparisons are unreliable
because of different survey methods (weirs, foot, or aerial; Fair et al. 2010). Most index streams
are tributaries to the mainstem in the Lower River or tributaries in the Chulitna and Talkeetna
subbasins (Fair et al. 2010). No index streams are located in the Middle Susitna River.
Total peak counts of Chinook salmon spawning in Middle River tributaries between 1981 and
1985 ranged from 1,121 to 7,180 fish with a median of 4,179 fish (Jennings 1985, Thompson et
al. 1986). As described above, generally over 90 percent of the Chinook salmon returns to the
Middle Susitna River have spawned in Indian or Portage creeks. Peak spawner counts from
1976 to 1984 ranged from 114 to 1,456 fish (median 479.5 fish) in Indian Creek and 140 to
5,446 fish (median 680.5 fish) in Portage Creek (Jennings 1985).
ADF&G used mark recapture techniques to estimate escapement to fishwheel stations during the
early 1980s (Figure 4.3-7). From 1982 to 1985, total escapement to Talkeetna Station ranged
from 10,900 to 24,591 fish (median 14,400 fish), but was considered an overestimate because
many Chinook salmon tagged at Talkeetna Station were found to have spawned in tributaries
downstream of Talkeetna Station (Jennings 1985).
Juvenile Chinook salmon exhibited very little freshwater life history diversity during studies
conducted in the 1980s. Scale samples from adult Chinook salmon collected at fishwheels
indicated that nearly all Chinook salmon that survive to adulthood exhibit a stream-type life
history pattern and outmigrate to the ocean as yearlings (ADF&G 1981, ADF&G 1983c, Barrett
et al. 1984, Barrett et al. 1985, Thompson et al. 1986). A small percentage of returning adult
Chinook salmon outmigrated as fry.
Roth and Stratton (1985) suggested Chinook salmon juveniles have three patterns of distribution
following emergence in tributary streams. One group rears and overwinters in the natal tributary,
and then outmigrates at Age 1+. Another group rears in the natal tributary during part of the first
summer, migrates to the mainstem for overwintering and additional rearing and eventually
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outmigration to the ocean, again at Age 1+. The third group migrates to the lower Susitna River
as fry. Roth and Stratton (1985) were uncertain what the relative proportion of Chinook
production used the three behavior patterns.
During 1980s studies, the bulk of Chinook salmon fry outmigrated from Indian and Portage
creeks by mid-August and redistributed into sloughs and side channels of the Middle Susitna
River or migrated to the Lower River (Roth and Stratton 1985, Roth et al. 1986; Figure 4.3-8).
Outmigrant trapping occurred at Talkeetna Station (RM 103) during open water periods from
1982 to 1985 and demonstrated Chinook salmon fry were migrating downstream to the Lower
Susitna River throughout the time traps were operating (Schmidt et al. 1983, Roth et al. 1984,
Roth and Stratton 1985, Roth et al. 1986; Figure 4.3-9). Based on timing of movements, Roth
and Stratton (1986) suggested that some Chinook salmon fry from the Middle Susitna River
either overwinter in the Lower Susitna River downstream of Flathorn Station or outmigrate to the
ocean as fry, but are unsuccessful, as demonstrated by the low prevalence of Age 0 outmigrant
characteristics in adult scales.
The capture of a small number of Age 1+ Chinook salmon juveniles in the Indian River during
winter sampling indicated that some Chinook salmon fry remain in natal tributaries throughout
their first year of life (Stratton 1986). During 1984, sampling in the Indian River failed to
capture any Chinook salmon Age 1+ fish during July, but were successful during May and June,
indicating that Age 1+ Chinook salmon juveniles emigrated from tributary streams shortly after
ice-out (Roth and Stratton 1985). The cumulative frequency of Age 1+ Chinook salmon
juveniles catch at the Talkeetna Station reached 90 percent by early July in 1985 and by late-July
at the Flathorn Station (Roth et al. 1986; Figure 4.3-10). Consequently, most outmigrating
Chinook salmon Age 1+ smolts are generally in estuarine or nearshore waters by mid-summer.
4.3.2.2.2. Sockeye Salmon
During the 1980s, sockeye salmon (O. nerka) entered the Susitna River in two runs (Jennings
1985); the first run was the smaller of the two with a run size generally of less than 15,000 fish
(Jennings 1985, Thompson et al. 1986). The second run was substantially larger with total
escapement estimates ranging from approximately 340,000 to 606,000 fish (ADF&G 1981,
Barrett et al.1983, Barrett et al. 1984, Barrett et al. 1985, Thompson et al. 1986; Figure 4.3-11).
Historically, sockeye salmon spawning in the lower Middle Susitna River was a relatively small
component to the total Susitna River run with peak spawner counts from 1981 to 1985 ranging
from 555 to 1,241 sockeye salmon (Jennings 1985, Thompson et al. 1986). Nevertheless, the use
of the middle river is important because these fish exhibit a life history pattern that is not
dependent upon lakes for juvenile rearing. While juvenile lake rearing is the norm for most
sockeye salmon populations, “river-type” and “ocean-type” life history patterns have also been
identified, particularly in glacial rivers (Gustafson and Winans 1999), such as the Susitna River
and several of its major tributaries.
Sockeye salmon are widely distributed in the Susitna River downstream of Devils Canyon
according to ADF&G’s Anadromous Waters Catalog (Figure 4.3-12Figure 4.3-), but are
especially prevalent in tributaries with accessible lake rearing habitat (Yanusz et al. 2011b).
Sockeye Salmon in the lower Middle Susitna River spawn almost exclusively in side sloughs
(Sautner et al. 1984). Sockeye salmon spawning was observed within 24 sloughs of the lower
Middle Susitna River from 1981 to 1985 (Jennings 1985, Thompson et al. 1986). There are no
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accessible juvenile rearing lakes with associated spawning areas accessible to sockeye salmon in
the Middle Susitna River. On rare occasions during the 1980s spawning surveys, one or two
pairs of sockeye were observed spawning along the edge of the main channel, tributaries, or in
side channels (ADF&G 1981, ADF&G 1983c, Barrett et al. 1984, Barrett et al. 1985, Thompson
et al. 1986). Sockeye salmon primarily spawned in Sloughs 11, 8A, and 21 (Figure 4.3-13).
Some sloughs were used for spawning by sockeye salmon in all years while others were only
intermittently used.
Although sockeye salmon spawning was rarely observed within tributaries of the Middle Susitna
River, Roth and Stratton (1985) reported the capture of sockeye salmon fry in the Indian River
during July and August 1984 and Yanusz et al. (2011a) reported the terminal location of one
radio-tagged sockeye salmon in the Indian River and one in Portage Creek during 2007. No
adult sockeye salmon were observed in tributaries to the Middle Susitna River during 1981
through 1983. Barrett et al. (1985) observed one sockeye salmon adult in Indian River and 12 in
Portage Creek during 1984, but suspected most were milling; only one pair of sockeye salmon
were spawning. During 1985, Thompson et al. (1986) observed two adult sockeye salmon in the
Indian River, but no spawning activity.
4.3.2.2.3. Chum Salmon
Chum salmon (O. keta) have been the most abundant anadromous salmon returning to the
Susitna River Basin with the exception of even-year pink salmon runs. Chum salmon have been
an important component to the commercial salmon fishery with an average of 478,000 caught in
the UCI Management Area during 1966 to 2006 (Merizon et al. 2010). Chum salmon also have
contributed to the sport fishery with an average of 2,893 captured during 1998 to 2007 (Merizon
et al. 2010).
Based upon sonar counts to the Yentna River plus the Peterson estimates to the Sunshine Station,
minimum chum salmon returns to the Susitna River averaged 440,751 fish (range 276,577 to
791,466) from 1981 through 19854 (ADF&G 1981, ADF&G 1983c, Barrett et al. 1984, Barrett et
al. 1985, Thompson et al. 1986; Figure 4.3-14). These counts were considered minimums
because sonar counts at the Yentna River station underestimated the total returns (Jennings
1985). The average returns to the Talkeetna Station during a similar time period was 54,640
chum salmon, but this was probably an overestimate since chum salmon have been documented
entering the Middle Susitna River and then migrating back downstream to spawn in Lower River
habitats. The Talkeetna Station was not operated during 1985. Average returns to Curry Station
were 21,993 fish (range 13,068 to 29,413) from 1981 to 1985. The returns to Curry Station were
likely reasonable estimates of the returns to the Middle Susitna River because all of the known
primary spawning areas are upstream of Curry Station.
Chum salmon are widely distributed in the Susitna River downstream of Devils Canyon
according to ADF&G’s Anadromous Waters Catalog (Figure 4.3-15). Merizon et al. (2010)
radio-tagged 239 chum salmon at Flathorn during 2009 and assigned a spawning location to 210
of the tagged fish. Chum salmon were strongly oriented toward the east or west banks.
4 No estimate was available for the Yentna River during 1985 and the estimate at the downstream Flathorn Station was 56,800
fish lower than the Sunshine estimate. Consequently, the minimum chum run size for 1985 was estimated using the Sunshine
estimate plus the four-year average at the Yentna Station from 1981 to 1984.
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Consequently, fish captured and tagged on the west side of the river primarily entered the Yentna
River, while those captured on the east side tended to migrate up the Susitna River. Ten (4.8
percent) of the 210 chum salmon tagged at Flathorn and assigned a spawning location were
assigned as spawning in the Middle Susitna River and none entered tributaries (Figure 4.3-16;
Merizon et al. 2010).
Spawning surveys were conducted each year from 1981 to 1985, but the level of intensity varied
from year to year. Chum salmon spawn primarily in clearwater tributary and side slough habitat
within the Middle Susitna River (Figure 4.3-4). Indian River and Portage Creek account for the
majority of tributary spawning in the Middle Susitna River while Sloughs 11, 8A, and 21
account for the majority of slough spawning (Figure 4.3-17). During 1984 Barrett et al. (1985)
identified 36 non-slough spawning areas in the mainstem of the Middle Susitna River. Peak
counts in these areas ranged from 1 to 131 (RM 136.1) chum salmon. During 1985, with
relatively poor viewing conditions, Thompson et al. (1986) identified three mainstem spawning
areas with 13 to 17 peak chum salmon counts.
While there is some uncertainty regarding the precise proportional distribution of chum salmon
among the different Susitna River spawning areas due to annual variations, the tributaries
associated with the Lower Susitna River are the major chum salmon production areas with lower
amounts of production from side sloughs, and occasional production from mainstem channels
and side-channels. Based upon the radiotracking conducted by Merizon et al. (2010), and the
studies conducted during the 1980s, the Middle Susitna River mainstem channels, sloughs, and
tributaries account for a small, but significant portion of the total river chum salmon production.
All chum salmon outmigrate to marine waters during their first year of life. Based upon the
catch of fry at incline plane traps, Roth et al. (1986) and Roth and Stratton (1985) concluded that
about 95 percent of chum salmon fry from the Middle Susitna River emigrated to the Lower
Susitna River by mid-July. During the period while present in the Middle Susitna River during
1983, chum fry were predominately observed in side sloughs (59%) and, tributaries (34%), but
were also observed occasionally in side channels (4%) and upland sloughs (3%; Dugan et al.
1984; Figure 4.3-18Figure 4.3-). However, most side channels were not sampled until early July
(e.g., side channels 10, 10A and Slough 22) and only one upland slough was sampled more than
once (Slough 6A; Figure 4.3-19). Consequently, chum use of these habitat types may be
somewhat higher than depicted in Figure 4.3-18.
4.3.2.2.4. Coho Salmon
Historically, coho salmon (O. kisutch) have been the least abundant anadromous salmon
returning to the Susitna River Basin. Coho salmon have been an important component to the
commercial salmon fishery with an average of 313,000 caught in the UCI Management Area
during 1966 to 2006 (Merizon et al. 2010). Next to Chinook salmon, coho salmon have been the
second highest contributor to the sport fishery with an average of 40,767 captured during 1998 to
2007 (Merizon et al. 2010).
Based upon sonar counts to the Yentna River plus the Peterson estimates to the Sunshine Station,
minimum coho salmon returns to the Susitna River have averaged 61,986 fish (range 24,038 to
112,874) from 1981 through 1985 (ADF&G 1981, ADF&G 1983c, Barrett et al. 1984, Barrett et
al. 1985, Thompson et al. (1986). These were considered minimums, because sonar counts at the
Yentna River station underestimated the total returns to the Yentna River (Jennings 1985). The
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average returns to the Talkeetna Station from 1981 to 1984 was 5,666 coho salmon (Figure 4.3-
20), but this was probably an overestimate, because radio-tracking studies and traditional tag
recaptures have indicated that coho salmon enter the Middle Susitna River and then migrate back
downstream to spawn. The Talkeetna Station fishwheel was not operated during 1985. Average
returns to Curry Station were 1,613 fish (range 761 to 2,438) from 1981 to 1985. The returns to
Curry Station were likely underestimates of the returns to the Middle River based on milling
behavior described previously and the fact that one of the known primary spawning areas,
Whiskers Creek, is downstream of Curry Station.
Coho salmon are widely distributed downstream of Devils Canyon according to ADF&G’s
Anadromous Waters Catalog (Figure 4.3-21). However, the terminal location of 275 radio-
tagged salmon during 2009 suggests the Middle Susitna River accounts for about 2 percent of the
Susitna River basin coho salmon production (Merizon et al. 2010; Figure 4.3-22). Coho salmon
spawn almost exclusively in clearwater tributary streams (Sautner 1984; Figure 4.3-4). During
1984 Barrett et al. (1985) identified one non-slough spawning area with two coho salmon along
the edge of the mainstem of the Middle Susitna River. However, that was the only observation
of non-tributary spawning of coho salmon in the middle river from 1981 through 1985.
Similar to Chinook salmon, coho salmon demonstrate three behavioral patterns following
emergence in tributaries (Roth and Stratton 1985). One group rears and overwinters in the natal
tributary, and then outmigrates at Age 1+ or 2+. Another group rears in the natal tributary during
part of the first summer but eventually migrates to the mainstem. Overwintering can occur in
tributaries, sloughs, beaver ponds or other areas. The third group migrates to the lower Susitna
River as fry.
The 1983 field work at JAHS sites by Dugan et al. (1984) indicated coho salmon juveniles had
relative high density distribution (51 percent) in tributaries (Figure 4.3-23), followed by upland
sloughs (35.3 percent). Side channels (4.0 percent) and side sloughs (9.8 percent) were
infrequently used by coho salmon. Overall catch rates for the JAHS sites in 1983 are depicted in
Figure 4.3-24. Relatively high catch rates for coho juveniles occurred at Chase Creek, Slough
6A, and Whiskers Creek.
4.3.2.2.5. Pink Salmon
Pink salmon (O. gorbuscha) have a strict two-year life history. Consequently, even and odd year
populations are genetically distinct stocks. During even years pink salmon are often the most
abundant anadromous salmon returning to the Susitna River Basin. Based upon sonar counts to
the Yentna River plus the Peterson estimates to the Sunshine Station, minimum pink salmon
returns to the Susitna River averaged 546,888 fish (range 85,554 to 1,386,321) from 1981
through 1985 (ADF&G 1981, ADF&G 1983c, Barrett et al. 1984, Barrett et al. 1985, Thompson
et al. (1986). These were considered minimums, because sonar counts at the Yentna River
station underestimated the total returns to the Yentna River (Jennings 1985). The average
returns to the Talkeetna Station fishwheel from 1981 to 1984 was 65,684 pink salmon (Figure
4.3-25), but this was probably an overestimate because traditional tag recaptures have indicated
pink salmon have entered the Middle Susitna River and then migrated back downstream to
spawn. The Talkeetna Station was not operated during 1985. Average returns to Curry Station
were 22,437 fish (range 1,041 to 58,835) from 1981 to 1985.
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Pink salmon are found in the mainstem Susitna River downstream of Devils Canyon and many
of tributary rivers and streams (Figure 4.3-26). Pink salmon spawn primarily in clearwater
tributary streams with small numbers observed in side channels or side sloughs (Sautner 1984;
Figure 4.3-4). Barrett et al. (1985) and Thompson et al. (1986) conducted intensive surveys in
1984 and 1985 and found pink salmon spawning in tributaries of the Lower and Middle Susitna
River and concluded that pink salmon did not spawn in main channel habitat. Indian River (RM
138.6), Portage Creek (RM 148.9), 4th of July Creek (RM 131.1), and Lane Creek (RM 113.6)
accounted for the majority of the pink salmon tributary spawning in the Middle Susitna River
(Figure 4.3-27). Pink salmon holding or spawning occurred in a number of sloughs within the
Middle Susitna River. Habitat use was not consistent from year to year. Barrett et al. (1984)
identified 17 sloughs that pink salmon occupied, but only ten of the sloughs were used for
spawning. Barrett et al. (1985) identified Sloughs 8A, 11, and 20 as the most important for pink
salmon spawning. In contrast, during 1985 Thompson et al. (1986) observed pink salmon in
seven sloughs and a peak dead fish count of 5 fish in Slough 16. During 1985, pink salmon were
only observed in one (Slough 20) of the three sloughs considered important during 1984. Use of
sloughs for spawning by pink salmon in the Middle Susitna River may in part depend upon run
strength, which is typically larger during even years.
Most pink salmon fry emerge from the gravel and outmigrate prior to complete ice breakup.
Consequently, there is little information on habitat use. Very few pink salmon fry were captured
as part of juvenile anadromous salmon studies during the 1980s.
4.3.2.2.6. Rainbow Trout
Rainbow trout (O. mykiss) are widely distributed in the Middle Susitna River and its tributaries
downstream of Devils Canyon. During 1982, rainbow trout were widely distributed at the 17
DFH sites (Schmidt et al. 1983); Figure 4.3-28Figure 4.3-). Rainbow trout were captured at all
DFH sites except Whitefish Slough. Rainbow trout catch was frequently higher and more
consistent at DFH sites associated with tributary streams (Lane Creek and Slough 8, 4th of July
Creek, Whiskers Creek and Slough) and clearwater sloughs (e.g., Slough 6A and Slough 8A).
Similar use of these tributaries and tributary mouths were observed during 1983 by Sundet and
Wenger (1984).
Adult rainbow trout utilize clearwater tributary habitats to spawn following ice break-up each
spring (Schmidt et al. 1983). After spawning, adults primarily hold and feed during the open
water period in tributary and tributary mouth habitats, although some utilization of clearwater
side slough habitat was observed during the 1980s (Schmidt et al. 1983). Holding and feeding
areas during the open water period were closely associated with Chinook, chum and pink salmon
spawning areas where it was suspected rainbow trout were feeding on salmon eggs (Sundet and
Pechek 1985). Juvenile rainbow trout generally utilize natal clearwater tributaries as nursery
habitats (Schmidt et al. 1983). Some juveniles also rear in the mainstem and sloughs, but the use
of these habitats appears to be limited (Schmidt et al. 1983, Sundet and Wenger 1984).
Movement from spawning or feeding tributaries to overwintering habitat is commonly in a
downstream direction (Sundet and Pechek 1985). Many adults overwinter relatively close (i.e.,
<4 miles) to spawning tributaries, while others exhibit long-distance migrations that typically
range from 10 to 20 miles downstream but can extend over 76 miles (Schmidt et al. 1983, Sundet
1986).
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Rainbow trout were also documented in lakes within the Susitna River basin. A total of 390 fish
were captured in six lakes surveyed in 1984, comprising 86 percent of the total fish catch
(Sundet and Pechek 1985). Lakes in which rainbow trout were abundant in 1984 include those
that flow into Fourth of July and Portage creeks (Sundet and Pechek 1985).
4.3.2.2.7. Arctic Grayling
In the Middle Susitna River, Arctic grayling primarily use mainstem habitats for overwintering
and tributaries for spawning and rearing (Schmidt et al. 1983, Sundet and Wenger 1984).
Upstream of Talkeetna, Arctic grayling move into tributaries to spawn in May and early June
(Schmidt et al. 1983, Sundet and Wenger 1984). During 1982, Arctic grayling were captured at
15 of the 17 DFH sites (Figure 4.3-29). Arctic grayling catch was highest at tributary mouths of
Indian River, Portage Creek, Lane Creek, 4th of July Creek, and Whiskers Creek and Slough.
After spawning, many adult grayling either remain within spawning tributaries or move to other
nearby tributaries to feed during summer (Delaney et al. 1981b, Schmidt et al. 1983, Sundet and
Pechek 1985). Arctic grayling also use tributary mouth, side slough and main channel habitats
during the open water season, though fish captured in these areas were typically of smaller size
than grayling in tributaries which may suggest that small individuals are displaced from
tributaries by larger, older fish (Schmidt et al. 1983, Sundet and Wenger 1984). During late
summer, most adult grayling disperse from tributaries to mainstem winter holding habitats
typically located in areas proximal to spawning tributaries, though winter movements of 10 to 35
miles were observed by tagged grayling (Sundet and Pechek 1985, Sundet 1986). Juvenile
Arctic grayling typically reside within their natal tributaries for at least one year, though some
age-0+ grayling were observed to move to tributary mouth habitats during late summer (Schmidt
et al. 1983).
4.3.2.2.8. Dolly Varden
Adult Dolly Varden are thought to primarily reside within tributary habitats during the open
water season (Schmidt et al. 1983). Movement into tributaries occurred in June and July during
1980s studies, coincident with the timing of upstream spawning migrations of adult Chinook
salmon (Delaney et al. 1981b, Schmidt et al. 1983). During late September and October adult
Dolly Varden are believed to spawn in the upstream extents of clear tributaries (Delaney et al.
1981b, Schmidt et al. 1983, Sautner and Stratton 1984).
Juvenile Dolly Varden in the Susitna Basin primarily utilize natal tributaries as summer and
winter nursery habitat (Delaney et al. 1981b, Sautner and Stratton 1983, Sundet and Wenger
1984). During winter, some juvenile Dolly Varden move downstream within natal tributaries
(Schmidt et al. 1983).
In the Middle Susitna River downstream of Devils Canyon, Dolly Varden are found primarily in
the upper reaches of tributaries and at tributary mouths (Schmidt et al. 1983, Sundet and Wenger
1984) but also in the mainstem for overwintering (Sundet and Wenger 1984). Spawning and
juvenile rearing areas are suspected to be in tributaries (Schmidt et al. 1983).
Surveys conducted in 1982 captured low numbers of Dolly Varden (28 fish) at nine (53%) of the
17 DFH sites sampled (Figure 4.3-30; Schmidt et al. 1983). Total Dolly Varden catch was
greatest at the Lane Creek and Slough 8 site (8 fish). Surveys conducted during 1981 and 1983
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had their highest catch of Dolly Varden at the mouth of Portage Creek and Indian River (Delaney
et al. 1981b, Sundet and Wenger 1984).
4.3.2.2.9. Burbot
Burbot were present throughout the mainstem of the Middle Susitna River during the 1980s
(Delaney et al. 1981b) and may be present in many of the larger tributaries such as the Talkeetna,
Chulitna, Yentna, and Deshka Rivers. However, surveys targeted for burbot have not been
conducted in many Susitna River tributaries. During 1982, burbot were captured at all DFH sites
surveyed in the Middle Susitna River (Figure 4.3-31Figure 4.3-, Schmidt et al. 1983). Sundet
and Wenger (1984) concluded from surveys conducted during 1981-1983 that few burbot spawn
in the Middle River downstream of Devils Canyon because relatively few juvenile were
observed upstream of the Three Rivers Confluences and fewer adult burbot were captured
upstream of the confluence compared to downstream (Delaney et al. 1981b, Schmidt et al.
1983,). Spawning areas used by burbot in the Middle Susitna River are unknown, but Sundet
and Wenger (1984) hypothesized that it occurred at sloughs and backwaters with ground water
and identified Slough 9 as one potential location due to the higher numbers of juveniles and
adults found at that location. In addition, Sundet and Pechek (1985) hypothesized that ice
processes may disrupt burbot spawning in the Middle Segment. They observed anchor ice
breaking away from substrate and floating to the surface in open water areas of the Middle
Segment, which they suspected might adversely affect burbot spawning success.
4.3.2.2.10. Round Whitefish
Round whitefish were present throughout the mainstem of the Middle Susitna River during the
1980s (Delaney et al. 1981b). Furthermore, abundance is higher upstream of the Three Rivers
Confluence compared to downstream (Schmidt et al. 1983). During the open water season, adult
round whitefish primarily use tributary, tributary mouth and slough habitats of the Susitna River
for feeding (Schmidt et al. 1983, Sundet and Wenger 1984). Many adult whitefish move into
large, clear tributaries in the Middle Segment of the Susitna River in June and return to mainstem
habitats in August and September (Schmidt et al. 1983, Sundet and Wenger 1984). Use of
mainstem habitats was also documented for spawning, juvenile rearing, and as a migration
corridor (Sundet and Wenger 1984).
Spawning occurs in the mainstem and at tributary mouths (Schmidt et al. 1983, Sundet and
Wenger 1984). During 1981 through 1983, nine spawning areas were identified upstream of
Talkeetna. Mainstem sites were: RM 100.8, 102.0, 102.6, 114.0, 142.0 and 147.0 (Sundet and
Wenger 1984). Round white fish also spawn in tributary mouths, such as Lane Creek, Indian
River and Portage Creek (Sundet and Wenger 1984). Juvenile round whitefish rear mainly in the
mainstem and sloughs (Schmidt et al. 1983, Sundet and Wenger 1984). Overwintering areas
used by round whitefish have not been identified (Schmidt et al. 1983).
During the 1982 surveys, round whitefish were captured at all sites by a variety of gear types
(Figure 4.3-32). Round whitefish catch was highest mouths of Portage Creek, Indian River,
Fourth of July Creek, and at Slough 9. Catch at JAHS sites during 1983 were not substantially
different. Relatively high catch rates were reported for Indian River, Portage Creek, Slough 8A,
and Jack Long Creek (Sundet and Wenger 1984). The highest catch rates (actual rates not
reported) for adult round whitefish during 1983 were between RM 147.0 to 148.0 (Sundet and
Wenger 1984).
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4.3.2.2.11. Humpback Whitefish
Humpback whitefish are less common than round whitefish in the Susitna River. They are
distributed throughout the Middle Susitna River mainstem downstream of Devils Canyon, but at
relatively low abundance (Delaney et al. 1981b, Schmidt et al. 1983, Sundet and Wenger 1984).
Relative abundance is lower upstream of the Three Rivers Confluence compared to downstream
(Schmidt et al. 1983), which may in part be due to humpback whitefish typically being an
anadromous species (Morrow 1980). During 1982, humpback whitefish were occasionally
captured in low numbers at DFH sites surveyed in the Middle River Segment (Figure 4.3-33).
During 1983 most juvenile humpback whitefish were captured by downstream migrant traps and
most adults were captured by fishwheel (Sundet and Wenger 1984). Sundet and Wenger (1984)
reported that gillnets, hoop nets, and boat electrofishing captured a few humpback whitefish at
JAHS sites including: Slough 8A (36 fish), Slough 6A (14 fish), and Slough 22 (9 juveniles).
4.3.2.2.12. Longnose Sucker
Longnose suckers are common throughout the Susitna River including the Middle River
Segment (Delaney et al. 1981b, 1981c; Schmidt et al. 1983). However, longnose sucker
abundance appears to be somewhat lower in the Middle Segment compared to the Lower River
(Sundet and Wenger 1984). In the Middle Susitna River downstream of Devils Canyon,
longnose suckers were primarily associated with tributary and slough mouths, although the
mainstem was also used throughout the open-water season (Schmidt et al. 1983, Sundet and
Wenger 1984). Longnose sucker were found in all 12 DFH sites sampled in the Middle Segment
during 1982 (Figure 4.3-34; Schmidt et al. 1983). Boat electrofishing surveys during 1983 were
not substantially different with longnose suckers observed to be most abundant in Slough 8A,
Lane Creek, Fourth of July Creek, a mainstem site between RM 147.0-RM 148.0, and Portage
Creek (Sundet and Wenger 1984).
4.3.2.2.13. Threespine Stickleback
The distribution and abundance of threespine stickleback (Gasterosteus aculeatus) appears to be
quite variable from year to year (Sundet and Wenger 1984). Delaney et al. (1981b) observed
threespine sticklebacks as far upstream as RM 146.9, but Schmidt et al. (1983) found them as far
as RM 101.2 (Whiskers Creek and Slough; Figure 4.3-35) during 1982, and Sundet and Wenger
(1984) observed them at RM 112.3. Threespine sticklebacks can be very numerous at a sited
some years, but absent during others. For example, Sundet and Wenger (1984) reported several
thousand sticklebacks were observed in Slough 6A during 1981, but none during 1982, and 77
during 1983. Sundet and Wenger (1984) hypothesized that annual population dynamics and
year-class strength could explain the variability and that 1981 was a strong year-class for
spawners because few (32 fish) young-of the year were captured by inclined plane traps during
1982, while over 1,400 sticklebacks (88% of those captured) were young-of-the year during
1983. Sundet and Wenger (1984) concluded that 1982 was a relatively week year class for
spawners, and 1983 was intermediate.
4.3.2.2.14. Sculpin
Sculpin appear to be present throughout the fishbearing waters of the Susitna Basin including the
Middle River Segment. Sculpin were only identified to family (Cottidae) during fishery studies
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conducted during the 1980s (ADF&G 1981, ADF&G 1982), but slimy sculpin (Cottus
congnatus) was considered the primary species observed (Delaney et al. 1981b). During 1982,
all sculpin catch was recording as cottid but reported as slimy sculpin (ADF&G 1982, Schmidt et
al. 1983). During some years (e.g., 1983; Sundet and Wenger 1984) catch summaries and
discussion of sculpin were not reported.
Sculpin were considered relatively sedentary with limited movement (Delaney et 1981b, Schmidt
et al. 1983). While sculpin were observed at nearly all sites, relative abundance tended to be
somewhat higher at areas with water contributed from a clearwater tributary (Delaney et al
1981b). During 1982, sculpin were captured at all DFH sites in the Middle River Segment
(Schmidt et al. 1983; Figure 4.3-36Figure 4.3-). During 1981, sculpin were observed at all
habitat locations sampled in the Middle River Segment, but not during all periods (Delaney et al.
1981b)
4.3.2.2.15. Arctic Lamprey
Arctic lamprey (Lethenteron japonicum) are present, but uncommon in the Middle Susitna River
Segment (Delaney.et al. 1981b, Schmidt et al. 1983, Sundet and Wenger 1984). During 1981,
Delaney et al. (1981) captured Arctic lamprey ammocoetes at Whiskers Creek using minnow
traps in early July and late August. During 1982, Schmidt et al. (1983) reported observations of
Arctic lamprey ammocoetes at Whiskers Creek and Slough and Gash Creek (RM 111.6). During
1983, Sundet and Wenger captured 25 Arctic lamprey at Chase Creek (RM 106.9).
4.3.2.3. Lower Susitna River
4.3.2.3.1. Chinook Salmon
Production of Chinook salmon from the Susitna River basin primarily occurs in tributaries to the
lower river segment (Fair et al. 2010), with substantial juvenile rearing in lateral habitats
associated with the mainstem (Suchanek et al. 1985). Most index streams surveyed by ADF&G
were tributaries to the mainstem in the Lower River or tributaries in the Chulitna and Talkeetna
subbasins (Fair et al. 2010). No index streams are located in the Middle Susitna River. The
Deshka River (RM 40.6) has the highest escapement of all tributaries with a median of 35,548
fish (Figure 4.3-37). ADF&G installed a counting weir in the Deshka River prior to the 1995
season to improve the accuracy of salmon escapement counts (Fair et al. (2010). All other index
streams generally have fewer than 5,000 fish spawning during peak surveys (Figure 4.3-38).
From 1982 to 1985, total escapement (point estimates) to Sunshine Station ranged from 52,900
to 185,700 fish with a median 103,614 (ADF&G 1983c, Barrett et al. 1984, Barrett et al. 1985,
Thompson et al. 1986).
Suchanek et al. (1985) sampled 20 JAHS sites in the Lower Susitna River during the 1984 open
water season (Table 4.2-2). They observed that Chinook juveniles, primarily fry, had the highest
density at tributary mouths (average of 1.5 fish per cell sampled), moderate density at side
channels (0.8 fish per cell), and low density at side sloughs (0.1 fish per cell). Relatively little
upland slough habitat is present in the Lower Susitna River and none were sampled during 1984.
Their observations generally confirmed the patterns of macrohabitat use reported by Dugan et al.
(1984) for the lower Middle Susitna River. They also observed that turbidity had a substantial
influence on habitat use by juvenile Chinook salmon. They concluded that areas with moderate
levels of turbidity (100 to 150 NTU) had the highest density of Chinook juveniles (Figure 4.3-
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39). Suchanek et al. (1985) concluded that side channels influenced by the Talkeetna River
plume were the most important rearing areas for Chinook salmon juveniles because of its effect
on turbidity levels.
4.3.2.3.2. Sockeye Salmon
Tributaries to the Lower Susitna River plus the Chulitna and Talkeetna rivers are the major
producers of sockeye salmon in the drainage. Based upon terminal locations of radio-tagged
adults, Yanusz et al. (2011a, 2011b), observed over 97 percent of the returning sockeye salmon
used these spawning areas. Fried (1994, as cited in Fair 2009) used sonar and fishwheel counts
data to estimate that between 41 and 59 percent of the sockeye salmon entering the Susitna River
between 1981 and 1985 spawned in the Yentna River drainage. During the two years (i.e., 1984
and 1985) when Peterson estimates were available from both the Sunshine Station and
Flathorn/Susitna Stations, data indicated that 21 to 30 percent of sockeye salmon spawned
upstream of Sunshine Station (Barrett et al. 1985,Thompson 1986). While there was some
uncertainty regarding the precise proportional distribution of sockeye salmon among the
different Susitna River subwatersheds (Fair 2009), the tributaries associated with the Lower
Susitna River were the major sockeye salmon production areas. In addition to the Yentna River,
other Lower River spawning areas included lakes in the Fish Creek drainage (RM 7.0),
Alexander Lake (Alexander Cree drainage, RM 10.1), Whitsol Lake (Kroto Slough drainage RM
35.2), Trapper and Neil Lakes (Deshka River drainage, RM 40), and Fish Lake (Birch Creek
drainage, RM 89.3). Spawning surveys conducted in the Lower Susitna River indicated that
sockeye salmon did not spawn in the main channel, tributary stream mouths or associated
sloughs (ADF&G 1981, ADF&G 1983c, Barrett et al. 1985).
Yanusz et al. (2007, 2011a, 2011b) radio-tagged 75 sockeye salmon captured by fishwheels at
Sunshine during 2006, 311 during 2007, and 253 during 2008. Sockeye salmon were also radio-
tagged at the Yentna Station. Tracking of tagged fish confirmed the historic data that indicated
sockeye salmon spawn primarily in Susitna River tributaries (Figure 4.3-40). Within the Susitna
River tributaries, spawning occurred in the main channel, sloughs, or in lake systems (inlets,
outlets, and beaches). It is of interest that during 2007 and 2008, more than half of the fish radio-
tagged at Sunshine were returning to the Larson Lake system in the Talkeetna River drainage
(Yanusz et al. 2011a, 2011b). Also during 2007 and 2008, approximately 2.6 percent and 1.8
percent, respectively, of the fish tagged at Sunshine spawned in habitats associated with the
mainstem river. During 2007, 17 fish tagged at Sunshine were not assigned a spawning location
(Yanusz et al. 2011b). These included seven fish last recorded below the Talkeetna River mouth,
one fish that moved downstream below the tagging location, one fish that was recorded in an off-
channel area, four fish (possibly two others) that were captured in the sport fishery, two fish that
moved downstream, and one fish that returned to Cook Inlet. Thus, the terminal locations
depicted in Figure 4.3-40 do not necessarily indicate final spawning locations for tagged fish.
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4.3.2.3.3. Chum Salmon
As discussed previously, minimum chum salmon returns to the Susitna River averaged 440,751
fish (range 276,577 to 791,466) from 1981 through 19855 based upon sonar counts to the Yentna
River plus the Peterson estimates to the Sunshine Station (ADF&G 1981, ADF&G 1983c,
Barrett et al. 1984, Barrett et al. 1985, Thompson et al. 1986; Figure 4.3-14). Based upon the
terminal location of radio-tagged fish tracked by Merizon et al. (2010), the majority of the
Susitna River Basin chum salmon production is from tributaries to the lower river including the
Yentna River (47%), Talkeetna River (13%), Deshka River (5%), and Chulitna River (4%;
Figure 4.3-16). However, a small but significant portion also use lateral habitats adjacent to the
mainstem within lower river and the smaller tributaries (Barrett et al. 1985, Thompson et al.
1986, Merizon et al. 2010). During 1984 Barrett et al. (1985) documented chum spawning in
twelve non-slough and five slough habitats in the mainstem of the Lower River upstream of the
Yentna River. Not all of these locations were used in 1985. For example, 795 chum were
observed to spawn in the Trapper Creek side channel during 1984, but none were reported
observed during 1985 (Barrett et al. 1985, Thompson et al. 1986).
Similar to the middle river, during the early 1980s nearly all chum salmon fry passed the
Flathorn Station incline plane trap by mid- to late-July. During 1984, chum catch rates at JAHS
sites were highest between Island Side Channel (RM 63.2) and Sucker Side Channel (RM 84.5;
Suchanek et al. 1985). Catch rates were also highest at side channels (0.6 fish per cell),
moderate at tributary mouths (0.1 fish per cell), and low at sloughs (0.01 fish per cell). However,
Suchanek et al. (1985) noted that few surveys occurred at sloughs during the period that most
chum could be present. Chum fry catch rates were highest in side channels with low turbidity
(Figure 4.3-41).
4.3.2.3.4. Coho Salmon
Based upon sonar counts to the Yentna River plus the Peterson estimates to the Sunshine Station,
minimum coho salmon returns to the Susitna River averaged 61,986 fish (range 24,038 to
112,874) from 1981 through 1985 (ADF&G 1981, ADF&G 1983c, Barrett et al. 1984, Barrett et
al. 1985, Thompson et al. 1986). Similar to the middle river, nearly all coho spawning is in
clearwater tributary habitat. Based upon the terminal location of radio-tagged fish tracked by
Merizon et al. (2010), the majority of fish spawn in tributaries of the Lower Susitna River
including the Yentna River (47%), Chulitna River (17%), Talkeetna River (7%) and Deshka
River (7%; Figure 4.3-22). During 1982, spawning surveys conducted at 811 sites in the Lower
Susitna River did not identify any coho salmon spawning in the main channel (ADF&G 1983c).
However, in 1984, Barrett et al. (1985) identified two non-slough (RM 87.5 and RM 90.3, 200 to
400 fish) and one slough (RM 57, 10 to 20 fish) spawning areas in the mainstem of the Lower
Susitna River. No coho salmon spawning was observed in main channel of the Lower Susitna
River during 1981 to 1983, and the lower river was not surveyed during 1985.
Similar to the middle river during 1983, surveys at JAHS sites during 1984 suggested coho
juveniles in the Lower Susitna River predominately reared in tributary mouths (observed at all 4
5 No estimate was available for the Yentna River during 1985 and the estimate at the downstream Flathorn Station was 56,800
fish lower than the Sunshine estimate. Consequently, the minimum chum run size for 1985 was estimated using the Sunshine
estimate plus the four-year average at the Yentna Station from 1981 to 1984.
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sites), and to a lesser extent at side channels (5 of 16 sites), and side sloughs (2 of 14 sites)
during the open water period (Suchanek et al. 1985). There are few upland sloughs in the Lower
Susitna River and none were sampled during 1984. JAHS sites with relatively high catch rates
of coho salmon included Caswell Creek mouth, Birch Slough, and Beaver Dam Slough (Figure
4.3-42).
4.3.2.3.5. Pink Salmon
Based upon sonar counts to the Yentna River plus the Peterson estimates to the Sunshine Station,
minimum pink salmon returns to the Susitna River averaged 546,888 fish (range 85,554 to
1,386,321) from 1981 through 1985 (ADF&G 1981, ADF&G 1983c, Barrett et al. 1984, Barrett
et al. 1985, Thompson et al. (1986), and most of these returns are to tributaries draining to the
Lower Susitna River (Figure 4.3-25Figure 4.3-). ADF&G has operated a counting weir at TRM
7.0 on the Deshka River (RM 40.6) since 1995. The weir was built and operated for counting
Chinook salmon. In recent years, the counting operation ceased prior to the completion of the
pink salmon run. Consequently, recent pink salmon escapement counts to the Deshka River
were underestimates. Nevertheless, the available information suggests the Deshka River has
been an important spawning tributary in the lower river for pink salmon with escapement
estimates of up to 1.2 million fish (Figure 4.3-43).
In the Lower Susitna River most pink salmon spawned in Birch Creek, Willow Creek, and
Sunshine Creek. During 1984, Barrett et al. (1985) identified both Birch Creek (5 percent of
peak survey counts) and Birch Creek Slough (59 percent of peak survey counts) as important
spawning locations in the Lower River. Birch Creek Slough was the only slough habitat in the
Lower River with significant pink salmon spawning during 1984. In contrast, during 1985,
Thompson et al. (1986) identified Birch Creek as a spawning area that accounted for 55 percent
of the peak survey counts in the Lower Susitna River. Most of the pink salmon counted in Birch
Creek Slough were live, up to 9,917 fish, while 222 or fewer pink salmon were dead. Thus, it is
possible that Birch Creek Slough provided holding habitat for fish spawning in Birch Creek, with
little to no spawning in the slough.
During 2012, ADF&G began a mark-recapture study to identify major spawning locations of
pink salmon throughout the Susitna River drainage (Cleary et al. in prep). Pink salmon are also
recorded incidentally at the Yentna River sonar site, which is operated primarily for sockeye
salmon and not considered to provide complete estimates of other species (Westerman and
Willette 2011). There are no pink salmon escapement goals in the Susitna River drainage (Fair
et al. 2010).
Similar to the Middle Susitna River, little is known about the distribution and abundance of pink
salmon fry in the Lower River because nearly all fry outmigrate prior to ice-out. Few pink fry
were captured as part of 1980s juvenile salmon distribution and abundance studies.
4.3.2.3.6. Rainbow Trout
Rainbow trout are present throughout the Lower Susitna River and likely in most of the
clearwater tributaries draining to the mainstem. However, their relative abundance in the
mainstem appears to be somewhat less in the Lower River and more variable compared to the
Middle Segment downstream of Devils Canyon (Delaney et al. 1981b, Schmidt et al. 1983).
Comparison of seasonal catch rates, Floy tag recoveries, and radiotracking of rainbow trout
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suggest that many rainbow trout spawn and rear within clearwater tributaries and overwinter
within the mainstem Susitna River (Delaney et al. 1981b, Schmidt et al. 1983, Sundet and
Wenger 1984, Sundet and Pechek 1985). For larger tributaries, such as the Deshka River,
Sundet and Pechek (1985) suggested some rainbow trout may overwinter within the tributary,
while others overwinter in the mainstem. During 1982 Schmidt et al. (1983) captured rainbow
trout at four of the five DFH sites sampled in the Lower River Segment, with the highest
numbers in Birch Creek and Slough and Sunshine Creek and Side Channel (Figure 4.3-28Figure
4.3-). During 1981 Delaney et al. (1981) reported catch of rainbow trout were more consistent
and relatively higher at Anderson Creek, Alexander Creek, and Deshka River sampling sites.
4.3.2.3.7. Arctic Grayling
Arctic grayling are present, usually near tributary mouths, but relatively uncommon in the Lower
Susitna River Segment compared to the Middle Segment. Jennings (1985) and Schmidt et al.
(1983) reported that Arctic grayling likely overwinter in the mainstem Susitna River, but spawn
and rear in tributary streams. During 1982, Schmidt et al. (1983) captured Arctic grayling at four
of the five DFH sites surveyed, but not during all survey periods, and the number captured were
6 fish or fewer. During September 1981, Delaney et al. (1981b) captured relatively high
numbers of Arctic grayling at the Kashwitna River (RM 61.0), Montana Creek (RM 77.0), and
Birch Creek Slough (RM 88.4).
4.3.2.3.8. Dolly Varden
Dolly Varden are present, but relatively uncommon in the mainstem of the Lower Susitna River
Segment. Spawning and rearing areas was suspected to primarily be in tributaries with some use
of the mainstem for overwintering (Schmidt et al. 1983). During 1982, Dolly Varden were
captured in low numbers (1 or 2 fish) at two of the five DFH sites sampled in the Lower River,
Sunshine Creek and Side Channel and Birch Creek and Slough (Figure 4.3-30). During 1981,
Delaney et al. (1981b) captured Dolly Varden at 8 to 20 percent of the habitat locations surveyed
during each two-week period in the Lower Susitna River. During both years capture of Dolly
Varden in the mainstem was usually associated with a nearby tributary mouth (Delaney et al.
1981b, Schmidt et al 1983).
4.3.2.3.9. Burbot
Burbot are relatively common in the Lower Susitna River and its larger tributaries such as the
Yentna, Deshka, Talkeetna, and Chulitna rivers and Alexander Creek. Winter radiotracking b y
Sundet (1966) documented use of the Deshka River by burbot. Surveys by Delaney et al.
(1981b) documented burbot in the Deshka River and Alexander Creek. Burbot were captured at
all five of the DFH sites sampled in the Lower Susitna River during 1982 (Figure 4.3-31) and
Schmidt et al. (1983) reported that patterns of distribution were similar to surveys conducted in
the 1981.
4.3.2.3.10. Round Whitefish
Round whitefish are present throughout the mainstem of the Lower Susitna River Segment, but
appear to be less abundant than in the Middle Segment (Jennings 1985). During 1982, round
whitefish were captured at each of the five DFH sites surveyed in the Lower River, but generally
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in low numbers (Schmidt et al. 1983; Figure 4.3-32Figure 4.3-). The highest number of round
whitefish captured in the Lower River was at Goose Creek 2 and Side Channel. In contrast, the
highest gillnet catch rate for round whitefish during 1981 was at the mouth of Sunshine Creek
(Delaney et al. 1981b), but survey results are difficult to compare between years. Schmidt et al.
(1983) reported that substantially more round whitefish were captured during 1982 because of
greater effort with boat electrofishing.
4.3.2.3.11. Humpback Whitefish
Humpback whitefish are found throughout the mainstem of the Lower Susitna River and more
abundant than the Middle River Segment (Jennings 1985). However, catch rates during 1981
and 1982 were highly variable from site to site and period to period, suggesting humpback
whitefish is, in general, a relatively uncommon species. During 1982, humpback whitefish were
captured at three of the five DFH sites surveyed, but not during every period (Schmidt et al.
1983; Figure 4.3-33). During 1981, humpback whitefish were captured at 10 to 30 percent of the
sites sampled during each two-week period in the Lower River Segment from June through
September, except late July when no humpback whitefish were captured (Delaney et al. 1981b).
4.3.2.3.12. Longnose Sucker
Longnose sucker are commonly found throughout the mainstem of the Lower Susitna River and
generally more abundant than the Middle River Segment downstream of Devils Canyon
(Schmidt et al. 1983, Jennings 1985). During 1982, longnose suckers were captured at all five of
the DFH sites surveyed (Figure 4.3-34) with relatively high catch reported for Goose Creek 2
and Side Channel, Rabideaux Creek and Slough, and Sunshine Creek and Slough (Schmidt et al
1983). During 1981, longnose sucker were captured at 11 to 50 percent of the sites sampled
during each two-week period in the Lower River Segment from June through September
(Delaney et al. 1981b). Areas noted for longnose sucker catch in the Lower River Segment
during 1981 include the Deshka River and Cache Creek Slough, Kroto Slough, and Sheep Creek
(Delaney et al. 1981b). Schmidt et al. (1983) suggested that increased catch of longnose sucker
near tributary mouths during spring were the result of spawning congregations.
4.3.2.3.13. Threespine Stickleback
Threespine sticklebacks are commonly found in the mainstem of the Lower Susitna River and
substantially more abundant than the Middle Segment downstream of Devils Canyon (Schmidt et
al. 1983, Jennings 1985). During 1982, threespine sticklebacks were captured at all five of the
DFH sites surveyed in the Lower Susitna River (Figure 4.3-35) with the highest catch occurring
at Whitefish Slough. Adult threespine sticklebacks were observed migrating upstream to spawn
during late May and early June 1982 (Schmidt et al. 1983). Subsequently, catch rates of adults
were relatively high over the early July spawning period, young of the year were observed during
late July and early August in similar areas, and catch rates of young of year threespine
sticklebacks increased during late August and September at incline plane traps (Schmidt et al.
1983). Jennings (1985) concluded that threespine stickleback likely spawned at tributary and
slough mouths.
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4.3.2.3.14. Sculpin
Similar to the Middle Susitna River Segment, sculpin (primarily slimy sculpin) are abundant
throughout the mainstem of the Lower Susitna River. Schmidt et al. (1983) captured sculpin at
all five of the DFH sites surveyed during 1982 (Figure 4.3-36). Delaney et al. (1981b).
Similarly, Delaney et al. (1981b) captured sculpin at 42 to 76 of the habitat location sites
surveyed during 1981. Sites influenced by clear water tributaries typically had higher catch rates
of sculpin during 1981 and the highest minnow trap catch rate was noted for Birch Creek.
4.3.2.3.15. Arctic Lamprey
Arctic lamprey are present in low numbers within the Lower Susitna River. Delaney et al.
(1981b) captured 30 Arctic lamprey were during 1981in the Lower River with the highest catch
rate occurring at Little Willow Creek (RM 50.5) during early September. Schmidt et al. (1983)
captured 32 Arctic lamprey at DFH sites in Lower River during 1982 of which 30 were captured
at Birch Creek and Slough.
4.3.2.3.16. Eulachon
Adult eulachon (Thaleichthys pacificus) have been observed in the Lower Susitna River up to
RM 50.5, but are more common downstream of the Yentna River near RM 29. Eulachon are an
anadromous fish with two runs that enter the river during late May to early June (Vincent-Lang
and Queral 1984). ADF&G (1984) identified 61 spawning areas used by eulachon during 1983
with about 70 percent of the areas occurring between RM 12.0 and RM 27.0. ADF&G (1984)
also reported that eulachon were observed to spawn in the Yentna River during 1982 and 1983,
but the amount of river used for spawning was not determined. ADF&G (1984) reported that
first run eulachon population size during 1982 and 1983 was approximately several hundred
thousand fish and the second run was about an order of magnitude higher.
4.3.2.3.17. Bering Cisco
Bering cisco (Coregonus laurettae) were collected incidentally to other studies during the 1980s
(Barrett et al. 1984). Consequently, information regarding Bering cisco distribution is relatively
imprecise, and abundance is largely unknown. Adult Bering cisco are apparently present in the
Lower Susitna River up to the Three Rivers Confluence during spawning runs (Jennings 1985).
However, ADF&G (1984) reported a few Bering cisco are sometimes captured at the Talkeetna
and Curry fishwheels at RM 103 and 120, respectively, and a single Bering Cisco was captured
at Fourth of July Creek during 1983. Bering cisco are an anadromous species that enters the
Susitna River in August with spawning completed by the third week of October (Barrett et al.
1984).
4.3.2.3.18. Ninespine Stickleback
Ninespine sticklebacks (Pungitius pungitius) are rare within the Lower Susitna River. Ninespine
stickleback were not captured during surveys conducted during 1981 to 1983. During 1984,
Sundet and Pechek (1985) captured 50 ninespine sticklebacks on August 5 near RM 57.2 and 10
were captured by an outmigrant trap at RM 22.4.
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4.3.2.3.19. Northern Pike
The northern pike (Esox lucius) is an invasive species within the Susitna River drainage, which
were illegally transplanted into several lakes of the Yentna River in the 1950s (Delaney et al.
1981b). During the 1980s Aquatic Studies Program five northern pike were captured: one in
Kroto Slough (RM 36.2), one at the Yenta Station fishwheel, and three at the Flathorn Station
fishwheel (RM 22.4). Since the 1980s, the range of northern pike in the Susitna River basin has
expanded greatly. Ivey et al. (2009) reported northern pike have been documented in Lower
River tributaries as far upstream as Rabideaux Creek (RM 83.1) and the suspected distribution
extends to tributaries up to the Three Rivers Confluence. There is little information specific to
the mainstem of the Susitna River regarding northern pike spawning, juvenile emergence, or
juvenile rearing. Telemetry studies suggest that adult northern pike do not migrate significant
distances within the Susitna Basin. A 1996 study found that over the course of one year, only
one out of 18 radio-tagged northern pike moved a distance greater than 10 km and many moved
less than 1 km (Rutz 1999).
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5. TECHNICAL MEMORANDUM – SELECTION OF TARGET
SPECIES AND DEVELOPMENT OF SPECIES PERIODICITY
INFORMATION FOR THE SUSITNA RIVER
Defining the species of interest (i.e., target species) and then developing an understanding of the
timing of different life stage functions for each of the species is an important aspect of instream
flow studies. Fish species have evolved their life history strategies around the climatic and
hydrologic patterns of a given riverine system. Such strategies are directed toward increasing
population viability by synching important life stage functions during periods of time affording
the greatest opportunities for the success of that lifestage. Thus, the timing of different life stage
functions (e.g., migration, spawning, egg incubation, fry and juvenile rearing, smoltification,
etc.) will differ by species generally, and even for a given species will vary both within
(depending upon local climatological and hydrologic conditions) and between watersheds.
Understanding the timing and duration of these life stage functions as they exist under an
unregulated flow regime is important for being able to evaluate potential changes that may occur
following construction and operation of a hydroelectric project.
Both the 1980s Su-Hydro studies and the Susitna-Watana studies proposed for 2013-2014
recognized the importance of defining target species and their life stage periodicities for
evaluating potential project effects. This TM summarizes the studies completed in the 1980s that
served to identify target species and the periodicities of their life stages, and then provides
summary information concerning the proposed methods for completing this as part of the 2013-
2014 studies. Unlike the fish summary information presented above that discusses fish
distributions on a reach basis, the target species and life stage information for the 1980s studies
was deemed best presented by species for each river reach.
5.1. Su-Hydro 1980s Studies
Based on information provided by Jennings (1985) and Delaney et al. (1981), the Susitna River
basin historically supported at least 20 fish species (Table 4.3-1), of which, with the exception of
northern pike, all were considered to be endemic to the basin. Fish species richness within the
Susitna Basin was generally highest in the Lower reach and lowest in the Upper reach and the
upper Middle reach section upstream of Devils Canyon (River Mile [RM 150 – RM 162]). Steep
channel gradients and high water velocities within Devils Canyon obstructed upstream passage
for many fish species.
5.1.1. Target Species Selection
Aquatic studies conducted in the Susitna River during the 1980s identified the periodicity of
habitat utilization of various fish species. Pacific salmon species (Chinook, sockeye, chum, coho
and pink salmon) were a primary focus of the 1980s studies and can be considered the primary
target species for many of those studies, although some studies specifically targeted other species
including other anadromous fish (e.g., eulachon), and resident species (see Section 4). Thus,
there was no single species that was designated as the target species for the instream flow
studies. Rather, the studies were designed to develop a general understanding of river use by all
species of fish. Certain species were however studied more intensely than others, a factor of
their importance relative to sport and commercial fisheries as well as the degree to which their
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habitats may be directly influenced by the Susitna Project. For example, as more information
was obtained concerning the habitat utilization of adult salmon, in particular spawning habitats,
more emphasis shifted to certain salmon species, in particular, sockeye and chum salmon. Both
of these species were found to utilize clear water lateral habitats that were hydraulically
connected to the main channel of the Susitna River for spawning (keying in on groundwater
upwelling areas) and because these habitats could be affected by the regulation of flows in the
Susitna River, understanding the responses of these habitats to mainstem flows was important.
The other salmon species including primarily Chinook and coho were found to spawn primarily
in other main rivers tributary to the lower Susitna River including the Yentna and Chulitna, as
well as smaller tributaries that enter directly to the river. However, studies of juvenile fish
habitat use indicated that the main channel as well as side channel, side slough and other lateral
habitats were frequently utilized by all species of salmon and therefore understanding how those
habitats functioned and were influenced by main channel flows was a central focus of many of
those studies.
Determining potential effects of the proposed operations of the Su-Hydro Project on different
species and lifestages of fish and their habitats in the Susitna River was never completed due to
funding cuts and project cancellation. The types of information and data that had been collected
at the end of the five years of study, suggest that the flow-effects evaluation may have ultimately
been more macro-habitat based rather than focused on one or more target species.
5.1.2. Species Periodicities
Periodicities of juvenile and adult salmon habitat utilization in the Middle and Lower River were
described during 1980s studies (see Section 4), and the more recent fisheries studies conducted
in the Susitna River during the 2000s (e.g., Merizon etc.) have provided supplemental
information. The periodicities of other fish species were also described during the 1980s studies.
However, the sampling methods employed then were not always well-suited for identifying and
monitoring the complex life history patterns exhibited by resident fish species. Some of the
species other than Pacific salmon for which periodicity information was described included:
rainbow trout, Arctic grayling, burbot, round whitefish, humpback whitefish, longnose sucker,
Dolly Varden, Bering cisco, and eulachon. Although some information is available for most
resident and anadromous non-salmonids in each of the three reaches delineated during the 1980s
studies (Upper, Middle and Lower), most data pertain to the Middle and Lower reaches
downstream of Devils Canyon (RM 152). In general, insufficient information was collected
during the 1980s studies to describe the periodicities of Arctic lamprey, Lake trout, Northern
pike, threespine stickleback, ninespine stickleback, and various sculpin species present in the
Susitna Basin. Information relating to periodicity of fish habitat use in the Upper Segment is
sparse relative to that of the Middle and Lower segments.
To the extent possible, the timing of use by macro-habitat type (main channel, side channel, side
slough, upland slough, tributary mouth and tributary; see Section 4) was provided by species and
life stage for each Segment (Upper, Middle, Lower) based on studies conducted in the Susitna
River. Habitat utilization data for some species and/or life stages in the Susitna River is sparse;
in these cases, the available information for this TM was consolidated among Susitna River
Segments and/or was supplemented by data not specific to the Susitna Basin (e.g., Morrow
1980).
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Adult salmon migration timing in the Susitna River was identified during the 1980s based
primarily on fish capture data at stationary fishwheels, which were operated in the main channel
at Curry (RM 120), Talkeetna (RM 103), Sunshine (RM 80), Susitna (RM 25.7), and Flathorn
(RM 22) stations (e.g., Barrett et al. 1985). Spawning distribution and timing was determined
from visual observation of salmon spawning locations recorded during foot, boat and aerial
surveys. Data from fishwheel operation and spawning distribution studies during the 2000s by
Yanusz et al. (2007, 2011b) and Merizon et al. (2010) provide additional information regarding
adult salmon migration timing and spawning distribution. Salmon spawning surveys during the
1980s were conducted in main channel, off-channel and tributary habitats with varying intensity
among Susitna River tributaries and mainstem areas between the Upper and Lower segments.
The periodicity of habitat use for adult freshwater resident and non-salmonid anadromous
species (i.e., Bering cisco and eulachon) was determined based primarily on 1980s studies to
identify juvenile and resident fish distribution and abundance in the Middle and Lower segments
(e.g., Schmidt et al. 1983). These studies utilized a variety of methods to capture juvenile and
resident fish species (see Section 4). Migration timing of adult resident and non-salmonid
anadromous species was based on fishwheel data in the Middle and Lower segments and on
information from summer and winter radio telemetry and capture-mark-recapture studies
designed to track patterns of fish movement and habitat use. Utilization of the Upper Segment
by resident fish species was derived from summer sampling of the impoundment area in 1982.
Information not available from Susitna River 1980s aquatic studies was obtained from literature
sources relating to fish populations in Alaska or regions with comparable climate.
The periodicity of egg incubation and development for all fish species is based on adult spawn
timing, available information regarding egg development time from fertilization to emergence,
and observations of fry emergence. Egg development and incubation studies were performed for
sockeye and chum salmon during winter in the Susitna River and/or simulated environments
during the 1980s, but site-specific egg development and fry emergence timing is less well
documented for other species. Consequently, data from similar regions and temperature regimes
were used to help estimate the period of egg incubation and development. Documented timing
of fry emergence in late winter or early spring also was used to identify the end of the egg
incubation period and start of fry emergence.
Juvenile fry and smolt movement timing for all species was estimated during the 1980s based
primarily on capture at stationary downstream migrant traps operated in the Susitna River main
channel at Talkeetna (RM 103) and Flathorn (RM 22) stations. Fish capture data from 1980s
summer and winter sampling were used to supplement outmigrant trap data and to identity
habitat utilization of anadromous and resident fish species. Capture sites visited during the
1980s and 2000s were located in all major meso-habitats between Susitna River RM 233.4 and
RM 7.1.
5.1.2.1. Chinook Salmon
The known distribution of Chinook salmon in the Susitna Basin extends from Oshetna Creek
(RM 233.4) to Cook Inlet at RM 0.0 (Jennings 1985, Thompson et al. 1986, Buckwalter 2011).
Estimated total adult Chinook salmon escapement in the Susitna Basin during 1976 – 1984
ranged from 10,453 to 77,937 based on peak counts of spawning survey reaches (Jennings 1985).
During the same period, Chinook salmon escapement to the Lower Susitna was consistently
highest among Susitna River subbasins (Jennings 1985). Chinook escapement to the Lower
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Susitna subbasin ranged from 43 to 58 percent of the total basin escapement during 1981 – 1984,
while the proportion of Middle Susitna subbasin escapement ranged from 7 to 11 percent of the
total escapement during the same period (Jennings 1985).
Juvenile Chinook salmon in the Susitna River typically exhibit one of three freshwater life
history patterns. One group of Chinook fry rear in their natal tributary for nearly one year prior
to emigrating to the ocean as age 1+ smolts, while a second group of Chinook disperse from
natal tributaries throughout the spring and summer to Susitna River main channel, side channel
and slough habitats in the Middle and Lower segments (Roth and Stratton 1985, Stratton 1986).
Winter studies during the 1980s suggest that most Chinook fry utilize the Lower Susitna as
winter nursery habitat (Stratton 1986). A third freshwater life history pattern, in which juvenile
Chinook emigrate to the ocean as age 0+ smolts, was either exhibited by very few juvenile
Chinook during the 1980s or was subject to high ocean mortality based on adult scale analyses
(Barrett et al. 1985, Roth and Stratton 1985, Suchanek et al. 1985). Age analysis of adult
Chinook scales in 1985 indicated that 5% of fish sampled had emigrated as age 0+ smolts
(Thompson et al. 1986).
5.1.2.1.1. Upper Segment
The upstream extent of documented adult Chinook salmon presence in the Upper Susitna River
is Kosina Creek (RM 206.8), while juvenile Chinook have been identified as far upstream as the
Oshetna River (RM 233.4) (Buckwater 2011, AEA unpublished data). Few observations of adult
Chinook salmon have been recorded in the Upper River and as a result, the timing of migration
and spawning is not well defined. Active Chinook spawning was observed in Kosina Creek
during late July, which suggests that the periods of adult Chinook migration and spawning in this
segment may be similar to that described for Chinook in the Middle Susitna River (Table 5.1-1)
(Buckwalter 2011). If so, the timing and duration of egg incubation and fry emergence would
also likely be comparable to the period described for the Middle Segment (Table 5.1-1).
Chinook fry were documented in Kosina Creek (RM 206.8) in 2003 and 2011 and in the Oshetna
River (RM 233.4) in 2003 (Buckwalter 2011). No Chinook salmon were identified in any Upper
River tributaries sampled during impoundment studies in 1982 (Deadman, Watana, Kosina and
Jay Creeks) or in Watana Creek (RM 194.1) or Deadman Creek (RM 186.7) during aerial
spawning surveys conducted in 1984 (Sautner and Stratton 1983, Barrett et al. 1985). The
periodicity of juvenile Chinook salmon rearing and migration are poorly defined in the Upper
River due to a paucity of data pertaining to juvenile Chinook presence and movement. It is
unclear whether juvenile Chinook captured in 2003 and 2011 in the Upper River were age 0+
and/or age 1+ (Buckwalter 2011). Periodicity of juvenile Chinook rearing and migration are
considered undefined until additional data are available.
5.1.2.1.2. Middle Segment
Adult Chinook salmon typically entered the Middle Susitna River during upstream spawning
migrations in early June of each year, with most movement occurring late June and early July
(Table 5.1-1). Adult Chinook primarily utilized main channel habitats for migration to access
spawning sites, which were distributed nearly exclusively in tributary habitat (ADF&G 1983a,
Jennings 1985, Thompson et al. 1986). Upstream migration into Middle Susitna River tributaries
was delayed from that of main channel migration and occurred from in mid-June through early
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August (Jennings 1985, Trihey & Associates and Entrix 1985). Most tributary migration
occurred during July (Table 5.1-1) (Jennings 1985).
The spawning period for Chinook salmon in the Middle Segment during the 1980s was early
July through late August, with the majority of spawning activity occurring between late July and
mid-August (Table 5.1-1) (Barrett et al. 1985, Jennings 1985, Thompson et al. 1986). Chinook
spawning occurred almost entirely in tributaries in the Middle Susitna, with occasional use of
habitat at tributary mouths (ADF&G 1983a, Jennings 1985, Thompson et al. 1986). Spawning
was observed at Cheechako Creek (RM 152.4) and Chinook Creek (RM 157) tributary mouths in
1982 but was not documented at similar habitats elsewhere in the Susitna Basin (ADF&G 1983a,
Barrett et al. 1985, Thompson et al. 1986). Chinook spawning was not documented in main
channel habitats during 1981 – 1985; however, surveys conducted during 1983 – 1985 did not
specifically target Chinook salmon (ADF&G 1983a, Barrett et al. 1984, Jennings 1985,
Thompson et al. 1986). The primary spawning tributaries during the 1980s were Indian River
and Portage Creek; annual peak index counts of live Chinook during 1981 – 1985 in these
streams accounted for over 90 percent of total annual peak index counts among Middle Susitna
tributaries (Jennings 1985, Thompson et al. 1986).
Chinook salmon egg incubation extends from the start of spawning in early July through juvenile
fry emergence, though egg development and the timing of fry emergence in this segment is not
well defined due to limited availability of winter sampling data. Chinook fry emergence began
prior to the start of outmigrant trap seasonal operation in mid-May 1983 and 1985, though ice
cover precluded trap operation prior to this point (Schmidt et al. 1983, Roth et al. 1986). Salmon
egg incubation time depends on water temperature and approximate time necessary for Chinook
egg development from the point of fertilization to fry emergence can range from 316 days at
water temperatures of 2° C to 191 days at 5° C (Murray and McPhail 1988, Quinn 2005). Based
on these data and approximate timing of Chinook emergence in similar areas, emergence in the
Susitna River is estimated to begin in early March (Table 5.1-1) (Scott and Crossman 1973,
Jennings 1985). Small size of juvenile Chinook captured during May and June suggests that
Chinook emergence may continue until early May or later (Roth and Stratton 1985). The small
size (35 mm) of some age-0+ Chinook captured at outmigrant traps in June and July of 1981,
1982 and 1983, supports the possibility that emergence may continue through May or beyond
(Table 5.1-1) (Jennings 1985).
Age 0+ Chinook salmon fry movement from natal tributaries was observed to peak at the start of
tributary sampling in June and continued through September in 1981, 1984, and 1985 (Delaney
et al. 1981a, Roth and Stratton 1985, Roth et al. 1986). These data, in conjunction with early
June presence of age 0+ Chinook in the mainstem Susitna River, indicate that the period of age
0+ fry migration from tributaries occurs from early May through mid-September, with most
movement in late May and July (Table 5.1-1) (Roth et al. 1984, Roth et al. 1986). Chinook that
remained in the Middle Segment primarily occupied tributary and side channel habitats during
the summer and side channels and side sloughs during winter (Figure 5.1-1) (Dugan et al. 1984).
Age 0+ Chinook that emigrated from the Middle Susitna River moved downstream to the Lower
River from early May through late September, and peak movement occurred in July and early
August (Table 5.1-1) (Roth et al. 1984, Roth and Stratton 1985, Roth et al. 1986). These
downstream migrant age 0+ Chinook either selected winter nursery habitats in the Lower Susitna
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or immigrated to estuarine habitats; the relative proportion of fish that demonstrated each life
history was not clear based on 1980s studies (Roth and Stratton 1985).
Age 1+ Chinook salmon utilized side channels and side sloughs as primary nursery habitats
during winter in the Middle Susitna, and tributary mouths, main channels, and upland sloughs as
secondary habitats. Based on winter capture data, emigration of age 1+ Chinook from natal
tributaries and mainstem nursery areas began in early winter and was mostly completed by July
(Table 5.1-1) (Stratton 1986, Roth et al. 1986). Catch records at the Talkeetna Station
outmigrant trap (RM 103) indicated that age 1+ Chinook emigration from mainstem areas started
prior to the late May start of trap operation in 1984 and 1985 (Roth and Stratton 1985, Roth et al.
1986). Outmigration data during 1983 – 1985 indicate age 1+ Chinook emigration from Middle
Susitna mainstem areas occurred from early May through mid-August, with most movement
between late May and early July (Table 5.1-1) (Roth et al. 1984, Roth and Stratton 1985, Roth et
al. 1986).
5.1.2.1.3. Lower River
Adult Chinook salmon entered the Lower Susitna River in late May and upstream migration to
tributary spawning sites continued through the spawn period in late August (Table 5.1-1) (Barrett
et al. 1984, Thompson et al. 1986). The peak of migration in the Lower River occurred during
the latter part of June (Barrett et al. 1984, Thompson et al. 1986). Susitna River fishwheels were
not operational prior to late May during the 1980s studies, so Chinook movement patterns prior
to this time are not well documented. The timing of upstream migration into tributaries is not
well documented in the Lower Susitna; however, based on main channel movement timing and
initiation of spawning in tributaries, tributary migration is estimated to occur from mid-June
through August (Table 5.1-1).
Chinook salmon spawning in the Lower Susitna River occurred entirely in tributary habitat with
no observed use of mainstem, side channel or slough habitats (Barrett et al. 1985, Thompson et
al. 1986). The Chinook spawn period in 1984 and 1985 in tributaries took place from early July
through late August, with the peak of spawning during the last three weeks of July (Table 5.1-1)
(Barrett et al. 1985, Thompson et al. 1986). Primary Chinook spawning tributaries in the Lower
Susitna River included the Yentna River (RM 28), Alexander Creek (RM 10.1), Deshka River
(RM 40.6), Willow Creek (RM 49.1), Montana Creek (RM 77.0), Talkeetna River (RM 97.1)
and Chulitna River (RM 98.5) (Jennings 1985). Chinook escapement in the Deshka River
accounted for at least 60 percent of the total annual Lower Susitna escapement in each year
during 1982 – 1984 (Jennings 1985).
The start of Chinook salmon egg incubation in the Lower Susitna River was coincident with the
start of spawning in early July and is presumed to be similar to estimated incubation and
emergence timing in the Middle Segment (Table 5.1-1) (Schmidt and Bingham 1983, Jennings
1985). Chinook fry emergence was estimated to occur during March, April though the small size
of juvenile Chinook captured in May and June indicate that the period may extend to early May
or later (Table 5.1-1) (Jennings 1985, Roth and Stratton 1985).
Dispersal of age 0+ Chinook salmon from natal tributaries in the Lower River was not well
defined during 1980s studies. Age 0+ Chinook fry were captured at main channel outmigrant
traps in early June during 1984 and 1985, which suggests that timing of tributary migrations
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began in mid-May (Table 5.1-1) (Roth and Stratton 1985, Roth et al. 1986). Weir catch on the
Deshka River (RM 40.6) indicated that age 0+ Chinook movement peaked during July and
continued through September (Delaney et al. 1981a, Roth and Stratton 1985). Age 0+ Chinook
migrated through the Lower Susitna main channel from late May through September, with peak
movement during late July and early August (Table 5.1-1) (Roth and Stratton 1985, Roth et al.
1986). Many of the age 0+ Chinook captured at outmigrant traps at Flathorn Station (RM 22)
were believed to emigrate to the ocean in their first year because few age 0+ fish were captured
downstream of this trap during 1984 site sampling efforts (Roth and Stratton 1985, Suchanek et
al. 1985).
Age 1+ Chinook salmon movement was not well documented for the Lower Susitna, but appears
to be similar to that of the Middle Segment based on available information. Migration of age 1+
Chinook from natal tributaries started in January and continued through July (Stratton 1986);
catch records from Lower Susitna tributaries indicated age 1+ Chinook were absent as of August,
but timing of peak movement is unclear due to sparse data (Table 5.1-1) (Schmidt et al. 1983).
Age 1+ migration from mainstem habitats appeared to start prior to the late May start of trapping
at the Flathorn Station (RM 22) in 1984 and 1985, and is assumed to have begun in early May
(Table 5.1-1). Catch at this trap indicates that movement age 1+ movement continued through
the end of August and peaked during late June and early July (Roth and Stratton 1985, Roth et al.
1986).
5.1.2.2. Sockeye Salmon
Sockeye salmon were distinguished during 1980s studies in terms of first and second runs based
on adult migration timing and spawning location (Jennings 1985, Thompson et al. 1986). First
run sockeye adult spawning and juvenile rearing occurred within the Fish Creek system in the
Talkeetna River Basin (RM 97.2) and in the Fish Lake system located within the Yentna River
(RM 30.1) during the 1980s (Thompson et al. 1986). Second run sockeye spawning and rearing
occurred within Susitna River mainstem and tributary habitats in the Middle and Lower
segments and were distributed from Devils Canyon (RM 150) to Cook Inlet (Barrett et al. 1985,
Jennings 1985, Thompson et al. 1986, Yanusz et al. 2007).
The first run of sockeye salmon was substantially smaller than the second run and was known
during the 1980s to only spawn within tributaries of the Talkeetna (RM 97.2) and Yentna (RM
30.1) rivers (Jennings 1985, Thompson et al. 1986). Total escapement in 1985 for first run
sockeye in the Susitna Basin was 11,750 (Thompson et al. 1986). Estimated escapement of
second run of sockeye salmon was 407,600 for the entire Susitna Basin, 120,800 at the Sunshine
Station fishwheel (RM 80) and 2,800 at the Curry Station fishwheel (RM 120) (Thompson et al.
1986). In 1984, estimated total basin escapement of second run sockeye was 605,800 and the
proportional abundance at Sunshine (RM 80) and Curry (RM 120) stations was similar to that
observed in 1985 (Barrett et al. 1985). Based on estimated escapements at sampling stations in
1984 and 1985, most second run sockeye within the Susitna Basin utilize tributaries downstream
of Sunshine Station (RM 80) (Barrett et al. 1985, Thompson et al. 1986).
Juvenile sockeye salmon in the Susitna River typically reside in freshwater nursery habitats for
one year prior to emigrating as age-1+ smolts, though adult scale analysis during the 1980s and
in 2008 indicate a portion emigrate as age-0+ or age-2+ smolts (Barrett et al. 1984, Barrett et al.
1985, Thompson et al. 1986, Yanusz et al. 2011b). In the Middle Segment, a substantial portion
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of age-0+ sockeye salmon fry redistribute from natal areas during the open water season to
nursery habitats in the Lower River, though some remain within the Middle Segment through
winter (Dugan et al. 1984, Roth and Stratton 1985, Roth et al. 1986). A portion of the Susitna
River sockeye emigrate to marine areas during the first year as age-0+, though the relative
proportion of juvenile sockeye salmon that exhibit this early life history type was believed to be
small based on the small proportion (less than 10 percent) of adult sockeye scales with this
pattern (Barrett et al. 1985, Thompson et al. 1986, Roth et al. 1986).
5.1.2.2.1. Middle Segment
Adult sockeye salmon in the Middle Segment, which are comprised of second run stock,
typically began upstream migration during the 1980s in early July with peak movement during
late July and early August (Table 5.1-2) (Jennings 1985, Thompson et al. 1986). Minimal
holding or milling behavior was observed by adult sockeye salmon, so observed main channel
migration timing at Curry (RM 120) and Talkeetna (RM 103) stations is likely similar to
upstream movements into side slough spawning sites (ADF&G 1983a). Adult sockeye in the
Middle Segment utilize main channel and side channel areas to access primary spawning areas in
side sloughs (Jennings 1985).
Nearly all sockeye spawning in the Middle Segment occurred within side sloughs, though active
spawning in the mainstem and occasional use of tributaries was observed (Jennings 1985,
Thompson et al. 1986). Sockeye salmon spawning in side sloughs occurred from early August
through early October and peaked during the month of September (Jennings 1985, Thompson et
al. 1986). Mainstem spawning in 1983 and 1984 was observed during mid- and late September,
while the few observations of adult sockeye spawning in tributaries occurred in early September
(Table 5.1-2) (Barrett et al. 1984, Barrett et al. 1985). Primary spawning sloughs in the Middle
Segment during the 1980s were Slough 21 (RM 141.1), Slough 11 (RM 135.3), and Slough 8A
(RM 125.1) (Jennings 1985).
Sockeye egg incubation in the Middle Segment is initiated at the start of spawning in early
August and is estimated to continue through May based on observations of sockeye egg
development during winter 1982 (Table 5.1-2) (Schmidt and Estes 1983, Jennings 1985, Roth
and Stratton 1985). Emergence timing for sockeye in side slough habitats is estimated to occur
from late March through May, though timing is likely variable among sites due to differences in
intergravel incubation conditions (e.g., water temperature and dissolved oxygen levels) (Table
5.1-2) (Schmidt and Estes 1983, Wangaard and Burger 1983, Jennings 1985). The duration of
incubation at two Middle Segment sites, Slough 11 (RM 135.3) and Slough 21 (RM 141.1), was
approximately 130-140 days and sockeye fry emergence was either initiated or completed at
these two sites by late April (Schmidt and Estes 1983). The wide size range of juvenile sockeye
salmon fry captured at outmigrant traps and Lower River sampling sites may indicate that
emergence continues over a long period (Roth and Stratton 1985).
Age-0+ juvenile sockeye salmon in the Middle Segment primarily utilize natal side sloughs and
upland sloughs for nursery habitat (Figure 5.1-1) (Schmidt et al. 1983, Dugan et al. 1984).
Juvenile sockeye capture data following breaching events in side sloughs in 1983 suggested that
age-0+ sockeye dispersed from breached side sloughs and redistributed to upland slough areas
during late summer (Dugan et al. 1984). Use of main channel, side channel, tributary and
tributary mouth habitats by juvenile sockeye in the Middle Segment was low during 1980s
studies (Dugan et al. 1984). Juvenile sockeye use of main channel and side channel areas was
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highest in backwatered areas with low water velocity (Dugan et al. 1984). Most age-0+ sockeye
from the Middle Segment disperse downstream during the open water season to either reside in
Lower River nursery habitats for the winter or emigrate to marine areas as age-0+ smolts (Roth
and Stratton 1985, Suchanek et al. 1985, Roth et al. 1986). Dispersal of age-0+ sockeye from
natal habitats was typically underway prior to the start of mainstem outmigrant trapping at
Talkeetna Station (RM 13), but likely began in early May, peaked in late June and July and
declined in September (Table 5.1-2) (Roth and Stratton 1985, Roth et al. 1986). High juvenile
sockeye use was observed in Side Slough 11 (RM 135.3) and upland Slough 6A (RM 112.3)
during summer 1983 (Dugan et al. 1984).
Age-1+ sockeye salmon typically began emigration from the Middle Segment prior to mainstem
outmigrant trap seasonal operation during the 1980s studies, but fyke net traps operated in Lower
River side channels suggest that downstream movement may have begun in early April (Table
5.1-2) (Bigler and Levesque 1985). Age-1+ migration peaked during late May and early June
and was completed by early or late July among sampling years in the 1980s (Table 5.1-2)
(Schmidt et al. 1983, Roth et al. 1984, Roth and Stratton 1985). Based on the low number of
age-1+ sockeye captured at outmigrant traps, it was hypothesized that most juvenile sockeye
salmon from the Middle Segment dispersed to the Lower River prior to winter (Roth et al. 1984,
Roth and Stratton 1985).
5.1.2.2.2. Lower River
First and second runs of adult sockeye utilize the Lower River of the Susitna River for migration
(Thompson et al. 1986). Migration of first run sockeye in the Lower River in 1984 occurred
during late May and June and appeared to peak in early June (Table 5.1-2) (Thompson et al.
1986). First run sockeye spawn exclusively in the Talkeetna and Yentna basins, so Lower River
use by this stock is for passage only (Barrett et al. 1985, Thompson et al. 1986). Second run
adult sockeye salmon migration occurs from early July through September with most movement
during late July and early August (Table 5.1-2) (Barrett et al. 1985, Thompson et al. 1986).
Second run sockeye spawn almost entirely within Lower River tributaries (Barrett et al. 1985,
Thompson et al. 1986, Yanusz et al. 2007, 2011b). No spawning was observed in main channel,
side slough, or tributary mouth habitats in 1984, though approximately 4 percent of adult
sockeye radio tagged in 2006 utilized mainstem areas for spawning (Barrett et al. 1985, Yanusz
et al. 2007). Second run sockeye spawn timing in the Lower River is estimated to occur from
late July through September and peak during August, though data are sparse for spawning
tributaries (Table 5.1-2) (Barrett et al. 1985, Thompson et al. 1986). Principal second run
spawning basins in the Lower River are the Talkeetna (RM 97.2) and Yentna (RM 30.1) rivers
(Barrett et al. 1985, Thompson et al. 1986, Yanusz et al. 2011b).
Sockeye egg incubation and fry emergence timing in mainstem areas of the Lower River are
likely similar to the period described in the Middle Segment (Table 5.1-2), though timing in
Lower River tributaries is not well defined. Egg incubation occurs from the start of spawning in
early August through May based on observations of sockeye egg development during winter
1982 (Table 5.1-2) (Schmidt and Estes 1983, Jennings 1985, Roth and Stratton 1985).
Emergence timing for sockeye in side slough habitats is estimated to occur from late March
through May, though timing can be dependent on site-specific intergravel incubation conditions
such as water temperature and dissolved oxygen levels (Table 5.1-2) (Schmidt and Estes 1983,
Wangaard and Burger 1983, Jennings 1985). Based on wide size ranges of juvenile sockeye
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salmon fry captured at outmigrant traps and Lower River sampling sites, the emergence period
may continue over a long period (Roth and Stratton 1985).
The majority of juvenile sockeye salmon in the Lower River use lacustrine nursery habitats
during freshwater residence, though a portion use areas associated with the mainstem Susitna
River (Suchanek et al. 1985). Age-0+ dispersal from natal areas to Lower River nursery habitats
occurred concurrently with movements in the Middle Segment, from early May through
September, though most movement was during late June, July and early August based on
outmigrant trap data at Talkeetna (RM 103) and Flathorn (RM 22) stations (Table 5.1-2) (Roth
and Stratton 1985, Suchanek et al. 1985). Low age-0+ sockeye abundance within the Lower
River mainstem areas soon after ice breakup was attributed to the general lack of mainstem adult
spawning habitat, while higher abundance during late June was likely a result of juvenile
sockeye redistribution from the Middle Segment (Suchanek et al. 1985). Juvenile sockeye
abundance in the Lower River was highest in tributary mouth habitats, though capture rates were
variable among these areas (Suchanek et al. 1985). Relative to tributary mouths, sockeye use
was low in main channel and side channels and minimal in side sloughs (Suchanek et al. 1985).
Highest capture rates of sockeye salmon were among habitats with low turbidity levels (75 – 125
NTU) (Suchanek et al. 1985). Juvenile sockeye abundance declined in breached side channels
with increasing main channel discharge, either due to elevated turbidity or current velocity levels
caused by breaching (Suchanek et al. 1985). Juvenile sockeye salmon abundance in the Lower
River was generally highest at Beaver Dam Slough and Side Channel (RM 86.3) and at Rolly
Creek mouth (39.0) among sampled sites (see Section 4) (Suchanek et al. 1985).
Age-1+ sockeye salmon emigration from Lower River habitats began in early April, based on
fyke net trapping data from Lower River side channels, and continued through mid- or late July
at the Flathorn Station (RM 22) outmigrant trap (Bigler and Levesque 1985, Roth and Stratton
1985). In 1984, most age-1+ sockeye migrated during late May and June (Table 5.1-4) (Roth
and Stratton 1985).
5.1.2.3. Chum Salmon
Chum salmon are distributed in the Susitna Basin from Devils Canyon (RM 150) downstream to
Cook Inlet (Jennings 1985, Thompson et al. 1986). Among Pacific salmon species, chum
salmon are the most abundant salmon species returning to the Susitna River, except during high
even-year pink salmon runs. The average combined annual chum salmon escapement in the
Yentna Basin and Susitna Basin upstream of RM 80 during 1981-1984 was 452,200; annual
escapement was not estimated for the Susitna Basin downstream of RM 80 during 1981-1983,
excepting the Yentna Basin (Jennings 1985). Escapement during 1981-1984 for the Middle
Segment, upstream of RM 103, was 54,600 (Jennings 1985). During 1980s studies, chum
spawning primarily occurred in the Talkeetna River Basin, whereas in 2009 radio telemetry data
indicated a larger chum escapement in the Yentna Basin (Barrett et al. 1985, Merizon et al.
2010). Approximately 4 percent of tagged chum in 2009 spawned in the Middle Segment and 14
percent used the Lower River and associated tributaries for spawning, excluding the Chulitna,
Talkeetna, and Yentna Rivers (Merizon et al. 2010).
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5.1.2.3.1. Middle River
Adult chum salmon migration in the Middle River of the Susitna River typically began in mid-
July during 1980s studies and peaked during September in mainstem and tributary habitats
(Table 5.1-3) (Jennings 1985, Thompson et al. 1986). Timing of entry into spawning tributaries
by adult chum can be delayed for a week or more as fish hold near the mouth of the tributary,
based on radio tag studies in the early 1980s (ADF&G 1981, ADF&G 1983a). Chum salmon
utilize a range of mainstem and tributary habitat to access Middle Segment spawning areas
located in tributary, side slough, side channel and main channel habitats (Jennings 1985).
Adult chum salmon primarily spawned in tributary and side slough habitats during the 1980s,
though some spawning occurred in mainstem habitats (Jennings 1985, Thompson et al. 1986).
Less than 10 percent of observed chum spawning during 1981-1984 occurred in mainstem
habitats in the Middle Segment (Jennings 1985). Spawn timing was observed to differ among
side slough, tributary and mainstem habitats (Jennings 1985). The tributary spawning period
was from early August through September and peaked in late August and early September (Table
5.1-3) (Barrett et al. 1985, Jennings 1985, Thompson et al. 1986). In side slough habitats, chum
spawning occurred from early August through mid-October, with peak activity occurring during
September (Table 5.1-3) (Barrett et al. 1985, Jennings 1985, Thompson et al. 1986). Mainstem
spawning occurred from early September through early October, though most chum spawned
during early September (Table 5.1-3) (Barrett et al. 1985, Jennings 1985, Thompson et al. 1986).
Portage Creek (RM 148.9), Indian River (RM 138.6) and 4th of July Creek (RM 131.1) were the
primary chum spawning tributaries during the 1980s, while sloughs 21 (RM 141.1), 11 (RM
135.3), and 8A (RM 125.1) were principal side sloughs used for spawning (Jennings 1985).
Incubation of chum salmon eggs began at the start of spawning in each habitat type: early August
in tributary and side sloughs, and early September in main channel areas (Table 5.1-3) (Barrett et
al. 1985, Jennings 1985, Thompson et al. 1986). Egg incubation conditions among these habitats
differ considerably, particularly in terms of water temperature, and such differences can affect
egg development timing (Wangaard and Burger 1983, Vining et al. 1985). Intergravel water
temperatures in tributary and main channel are strongly influenced by surface streamflow, which
suggests that incubation temperatures are high during fall and near freezing during winter
(Vining et al. 1985). In contrast, intergravel water temperatures in side slough habitats are
typically higher relative to tributary and main channel areas during winter due to the influence of
thermally stable groundwater upwelling (Vining et al. 1985). Timing of chum fry emergence in
tributary and main channel areas is estimated to begin in early March, approximately two weeks
later than the estimated start of emergence in side slough areas, based on evaluation of chum egg
incubation and development in variable temperature regimes (Table 5.1-3) (Wangaard and
Burger 1983, Vining et al. 1985). The duration of chum emergence periods among habitats are
not well defined due to sampling difficulty during this time, however, based on the small size of
juvenile chum captured at downstream traps in late May, it is assumed that emergence in
tributary and main channel areas extends through mid-May (Table 5.1-3) (Bigler and Levesque
1985, Roth and Stratton 1985).
Juvenile chum salmon emigrate from the natal habitats to marine areas as age-0+ smolts, though
some may feed within nursery habitats for one to three months prior to or during migration
(Morrow 1980, ADF&G 1983c, Jennings 1985). Primary nursery habitats for age-0+ chum
generally corresponded with areas highly utilized by adult chum spawners (i.e., tributary and side
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slough) (Figure 5.1-1); areas with the highest juvenile density also supported the highest
spawning density (Jennings 1985, Dugan et al. 1984). Tributary mouths and side channels were
also occupied by juvenile chum, though their use was low relative to side slough and tributary
areas (Figure 5.1-1) (Schmidt et al. 1983). Downstream migration of juvenile chum began prior
to the start of outmigrant trap seasonal operation in mid- and late May 1983 and 1985, and fyke
trap data collected in the Lower River suggest an early May start of juvenile chum movement
(Dugan et al. 1984, Roth et al. 1986). Based on these capture data, age-0+ chum movement in
the Middle Segment is estimated to occur from early May through mid-August and peak during
late May and June, though peak timing was variable during the 1980s and correlated with Susitna
River discharge levels (Table 5.1-3) (Roth et al. 1984, Dugan et al. 1984, Roth et al. 1986). The
vast majority (> 95 percent) of juvenile chum movement was completed by mid-July during
1980s studies (Jennings 1985, Roth et al. 1986).
5.1.2.3.2. Lower River
Adult chum salmon spawning migration in the Lower River of the Susitna River during the
1980s began in early July, peaked during late July and early August and continued through the
end of spawning in early October (Table 5.1-3) (Barrett et al. 1985, Thompson et al. 1986).
Timing of entry into Lower River tributaries is likely delayed approximately one to two week
from mainstem movement based on observations of adult chum behavior during radio telemetry
studies in the 1980s (Table 5.1-3) (ADF&G 1981, ADF&G 1983a). Adult chum passage occurs
in a variety of Lower River mainstem habitats to access tributary, tributary mouth, side slough,
side channel and main channel spawning areas (Barrett et al. 1985, Thompson et al. 1986).
In the Lower River, adult chum spawned in tributaries, tributary mouths, side channel, side
slough, and main channel habitats and spawn timing appeared to differ among habitats during
1980s studies (Barrett et al. 1985, Thompson et al. 1986). Spawning in tributary and tributary
mouth habitats occurred from mid-July through September and peaked during late July and early
August (Table 5.1-3) (Barrett et al. 1985). Among main channel, side channel and side slough
habitats, chum spawning started in late August, peaked in early September and was completed in
early October (Table 5.1-3). Tributaries and tributary mouths were primary spawning areas for
chum in the Lower River during 1984; high utilization of Lower River side channels by juvenile
chum during 1984 possibly indicated high spawning use, though this could not be verified during
spawn surveys (Barrett et al. 1985, Suchanek et al. 1985). In 2009, similar proportions of tagged
adult chum used mainstem (i.e., tributary mouth, side channel, side slough, and main channel)
habitats for spawning relative to tributaries (Merizon et al. 2010). The presence of groundwater
upwelling was noted at most main channel, side channel and side slough spawning sites (Barrett
et al. 1985). The Yentna and Talkeetna Rivers were primary spawning tributaries for chum
salmon in the Lower River, while Birch Creek Slough (RM 88.4) was an important side slough
(Barrett et al. 1985).
The periods of chum egg incubation and fry emergence is considered to be similar to that of the
Middle River, though utilization of spawning habitat is distinct between segments. Egg
incubation began in early August in tributary and tributary mouth sites and in early September at
main channel, side channel and side slough areas (Table 5.1-3). Specific information on egg
development and intergravel incubation conditions are lacking for spawning sites in the Lower
River (see Section 3.4.1), but the duration of incubation and timing of fry emergence is assumed
to resemble Middle Segment timing. Timing of chum fry emergence in tributary and mainstem
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areas is estimated to begin in early March and extend through mid-May, based on capture timing
at fyke net trap operated on Lower River side channels and the size of chum captured at
outmigrant traps in late May (Table 5.1-3) (Bigler and Levesque 1985, Roth and Stratton 1985).
Prior to emigration, age 0+ juvenile chum salmon in the Lower River were widely distributed
among habitat types during late spring and early summer, though the highest densities were
captured in side channel and tributary mouth habitats (Suchanek et al. 1985). Juvenile chum
distribution reflected that of adult chum spawning; low use of side slough habitats relative to
tributary mouths by chum fry was an indication of the low number of side sloughs in the Lower
River used for chum spawning (Suchanek et al. 1985). Side channel use by juvenile chum may
have been an indication of adult chum spawning in such habitats, however, the prevalence of
spawning in Lower River side channels could not be assessed due to insufficient sampling
coverage (Suchanek et al. 1985). The period of age-0+ chum salmon emigration from the Lower
River is similar to that described for the Middle Segment; age-0+ chum emigration from the
Lower River is estimated to occur from early May through mid-August and peak during late May
and June (Table 5.1-3) (Bigler and Levesque 1985, Roth and Stratton 1985, Roth et al. 1986).
Emigration started prior to outmigrant trap seasonal operation, but fyke net trapping on Lower
River side channels suggest an early or mid-May start of movement (Bigler and Levesque 1985).
During downstream migration, juvenile chum primarily utilized side channel habitats and use of
side channels mostly occurred prior to high turbidity levels, which are typically elevated from
June to August (Suchanek et al. 1985). Age-0+ chum capture was highest in habitats of low
turbidity (less than 50 NTU) and lowest in areas with turbidity values greater than 200 NTU
(Suchanek at al. 1985). Use of tributary mouths by emigrant chum was low relative to side
channel areas (Suchanek et al. 1985).
5.1.2.4. Coho Salmon
Coho salmon distribution in Susitna River Basin extends from Portage Creek (RM 148.9)
downstream to Cook Inlet (Jennings 1985, Thompson et al. 1986). Average combined
escapement for coho salmon in the Yentna Basin and Susitna Basin upstream of RM 80 during
1981-1984 was 61,400; annual escapement was not estimated for the Susitna Basin downstream
of RM 80 during 1981-1983, excepting the Yentna Basin (Jennings 1985). During 1981-1984,
average escapement at the Talkeetna Station (RM 103) fishwheel was 5,700, while averaged
escapement estimates at the Sunshine Station (RM 80) and Yentna River Station (RM 28.0, TRM
4.0) were 43,900 and 19,600 fish, respectively, during the same time period (Jennings 1985).
Total coho salmon escapement in the Susitna Basin was estimated to be 663,000 in 2002
(Willette et al. 2003).
Most juvenile coho salmon in the Susitna Basin reside in nursery habitats for 1 or 2 years prior to
emigrating as age-1+ and age-2+ smolts to marine areas, based on scale analysis of returning
adults (Barrett et al. 1984, Barrett et al. 1985). The proportions of coho that emigrate as age-1+
and age-2+ varied among years during the 1980s, though approximately equal proportions of
adults exhibited each life history (Barrett et al. 1984, Barrett et al. 1985). A small portion (< 5
percent) of juvenile coho emigrated as age-3+ smolts (Barrett et al. 1984, Barrett et al. 1985).
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5.1.2.4.1. Middle River
Upstream spawning migration of adult coho salmon into the Middle River of the Susitna River
typically began in late July and continued through early October based on studies conducted in
during the 1980s, with peak movement during early and mid-August (Table 5.1-4) (Jennings
1985, Thompson et al. 1986). Adult coho primarily used main channel areas for migration to
access tributary spawning sites (Jennings 1985). Timing of upstream migration into spawning
tributaries was delayed from main channel movement due to holding and milling behavior by
adult coho in the lower extent of the Middle Segment or proximal to spawning tributaries
(ADF&G 1981, ADF&G 1983a). Based on observed milling and/or delay between date of radio
tagging and tributary entry, the timing of tributary entry and upstream migration is estimated to
occur from early August through early October, with peak movement in late August and early
September (Table 5.1-4).
Adult coho salmon spawning occurred almost entirely within clear water tributaries, though
occasional use of one main channel habitat has been observed in the Middle Segment (ADF&G
1984, Barrett et al. 1985, Merizon et al. 2010). Radio tracking studies conducted in 2009
indicated that approximately 1 percent of all tagged coho salmon (n = 275) spawned in mainstem
(i.e., main channel, side channel and/or off-channel) habitats in the Middle Segment (Merizon et
al. 2010). No spawning was observed by coho salmon in surveyed slough or tributary mouth
habitats during 1980s studies (Barrett et al. 1985, Jennings 1985). Coho spawning during 1980s
studies occurred from mid-August through early October and peaked during mid- and late
September (Table 5.1-4). The spawn period for coho salmon main channel spawning is assumed
to be the same as tributary spawning due to sparse main channel spawning data. Primary
spawning tributaries in the Middle Segment are Indian River (RM 138.6), Gash Creek (RM
111.6), Chase Creek (RM 106.4), and Whiskers Creek (RM 101.4) (Jennings 1985, Thompson et
al. 1986).
The timing and duration of coho egg incubation and fry emergency is not well defined in the
Susitna River due to sparse winter data. The incubation period is considered to coincide with the
start of spawning in mid-August and continue through fry emergence (Table 5.1-4). Coho fry
emergence began prior to the start of outmigrant trap seasonal operation in mid-May 1983 and
1985, though ice cover precluded trap operation prior to this point (Schmidt et al. 1983, Roth et
al. 1986). Salmon egg incubation time depends on water temperature and the duration necessary
for coho egg development from the point of fertilization to fry emergence can range from 228
days at water temperatures of 2° C to 139 days at 5° C (Murray and McPhail 1988, Quinn 2005).
Based on these data and approximate timing of coho salmon emergence in similar areas, coho fry
emergence in the Susitna River is estimated to begin in early March (Table 5.1-4) (Scott and
Crossman 1973). The small size (35 mm) of age-0+ coho captured in June and July of 1981,
1982 and 1983 suggests that emergence may continue through May or beyond (Table 5.1-4)
(Jennings 1985).
Age 0+ coho salmon utilized natal tributaries for nursery habitats immediately following
emergence, but many emigrated from tributaries soon after emergence to mainstem habitats
between early May through October (Table 5.1-4; Figure 5.1-1) (Jennings 1985). Within the
Susitna River mainstem, age-0+ coho primarily used clear upland sloughs and side sloughs
relative to turbid areas affected by main channel streamflow (Figure 5.1-1) (Schmidt and
Bingham 1983, Dugan et al. 1984). Many age-0+ coho salmon moved downstream to the Lower
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River during the open water period based on outmigrant trap catch data (Roth et al. 1984).
Downstream movement of age-0+ coho to the Lower River appeared to begin in early May, prior
to outmigrant trap seasonal operation each year, and continued through October, with peak
movement from late June to late August (Table 5.1-4) (Jennings 1985, Roth et al. 1986).
Observed movement by age-0+ coho observed in September and October may have been a
reflection of dispersal to suitable winter nursery habitats, which were primarily located in side
sloughs and upland sloughs in the Middle Segment (Jennings 1985, Roth et al. 1986). Catch at
the Flathorn Station (RM 22) outmigrant trap during fall suggested that some age-0+ coho may
have immigrated to marine or estuarine areas (Roth and Stratton 1985).
Ages-1+ and 2+ coho salmon primarily utilize clear water natal tributaries, side sloughs, and
upland sloughs as nursery habitat in the Middle Segment (Dugan et al. 1984). Juvenile coho
salmon that remain in the Susitna Basin as age-1+ parr, typically disperse from natal tributaries
and mainstem nursery habitats within the Middle Segment to Lower River habitats, as few age-
2+ coho were captured within the Middle Segment during the 1980s (Stratton 1986). Coho parr
that remain within the Middle Segment during winter utilize tributaries, side sloughs and upland
sloughs as nursery habitats (Delaney et al. 1981a, Stratton 1986). During winter and early
spring, juvenile coho parr disperse from nursery habitats, though the timing and pattern of this
movement is not well understood. Limited data collected during winter 1984-1985 suggested
that juvenile coho parr exhibit similar movements as juvenile Chinook salmon, in that
downstream migration from tributaries, and possibly mainstem nursery habitats, begins between
early November and February (Table 5.1-4) (Stratton 1986). Downstream movement of age-1+
coho from the Middle Segment occurs throughout the open water season, with peak activity
between late May and early July (Table 5.1-4) (Schmidt et al. 1983, Roth et al. 1984, Roth et al.
1986). Age 2+ emigration from the Middle Segment habitats begins in early winter and
continues through June, with peak migration in late May and early June (Table 5.1-4) (Schmidt
et al. 1983, Roth et al. 1984, Roth et al. 1986).
5.1.2.4.2. Lower River
Adult coho salmon migration timing in the main channel areas of the Lower River occurred from
early July through early October during studies conducted in the 1980s, with peak passage in late
July and early August (Table 5.1-4) (Roth and Stratton 1985, Roth et al. 1986). Migration into
tributary spawning habitats is estimated to start in mid- or late July and peak during the month of
August (Table 5.1-4) (Roth and Stratton 1985, Roth et al. 1986).
Spawn timing of adult coho salmon in Lower River tributaries is slightly earlier relative to
Middle Segment streams, and occurs from early or mid-August through early October, with peak
spawning in late August and early September (Table 5.1-4) (Roth et al. 1986). Coho salmon
spawning in the Lower River occurred almost entirely in tributary habitats during the 1980s
studies, though approximately 13 percent of adult coho tagged in 2009 studies utilized Lower
River mainstem areas (i.e., main channel, side channel and/or off-channel) for spawning (Roth
and Stratton 1985, Roth et al. 1986, Merizon et al. 2010). No spawning was observed by coho
salmon in surveyed slough or tributary mouth habitats in 1984 (Barrett et al. 1985). Primary
coho spawning tributaries for coho salmon in the Lower River based on 1980s and 2009 data are
the Chulitna, Deshka and Yentna rivers (Thompson et al. 1986, Merizon et al. 2010).
The timing and duration of coho salmon egg incubation and fry emergence is not well defined in
the Susitna Basin due to limited information. The start of egg incubation begins coincident with
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the start of spawning in early August and is estimated to continue through emergence in May
(Table 5.1-4) (see Section 3.5.1). Juvenile coho fry emergence is believed to begin in March and
likely continues through May or later based on the small size of coho captured during June and
July during the 1980s (Table 5.1-4) (Jennings 1985, Roth and Stratton 1985).
Following emergence, age 0+ coho salmon utilized natal tributaries for nursery habitat and a
portion of individuals emigrated from tributaries to mainstem habitats. Age-0+ coho dispersed to
mainstem habitats throughout the open water season, but peak movement occurred during late
June, July and early August (Table 5.1-4) (Suchanek et al. 1985). Within the Lower River
mainstem, age-0+ coho primarily used tributary mouths as nursery habitats, with little
comparative use of side channel or side slough habitats (Suchanek et al. 1985). Many age-0+
coho salmon from the Middle Segment disperse downstream to suitable habitats in the Lower
River during the open water period and a portion of age-0+ coho may emigrate to marine or
estuarine areas during September and October based on capture at the Flathorn Station (RM 22)
outmigrant trap (Roth and Stratton 1985).
Juvenile coho salmon parr (age-1+ and age-2+) primarily utilized natal tributaries and tributary
mouths, side sloughs, and upland sloughs as nursery habitat during the freshwater rearing period
(Dugan et al. 1984). Age-1+ coho in the Lower River redistribute to suitable habitats throughout
the open water season, while a portion immigrate as smolts to estuarine areas (Roth et al. 1986).
Age-2 coho were believed to rear primarily in Lower River habitats during winter based on low
capture rates of age-2 fish in the Middle Segment during winter (Stratton 1986). During winter,
coho parr in the Lower River used tributary mouths and side channels for nursery habitat
(Delaney et al. 1981a, Stratton 1986). Age-1+ and age-2+ coho are believed to begin emigration
from nursery habitats in early winter, based on limited data collected during winter in the Middle
Segment, though the peak of mainstem movement likely occurs during the open water season
(Roth et al. 1986, Stratton 1986). Age-1+ coho movement at the Flathorn Station (RM 22)
occurred through October with peak emigration during August (Table 5.1-4) (Roth et al. 1986).
Age-2+ coho emigration from the Lower River is estimated to occur between early January
through mid-July and peak during June (Table 5.1-4) (Roth et al. 1986).
5.1.2.5. Pink Salmon
Pink salmon exhibit a two-year life cycle such that each spawning population is genetically
distinct. In the Susitna Basin, the even-year pink salmon population is substantially larger than
the population that spawns during odd years (Jennings 1985). Average combined escapement for
the Yentna Basin and Susitna Basin upstream of RM 80 during 1981 to 1984 was 1,138,400 for
even-year pink salmon and 93,400 for odd-year pink salmon; annual escapement was not
estimated for the Susitna River downstream of RM 80 during 1981-1983, excepting the Yentna
Basin (Jennings 1985). In 1984, estimated pink salmon escapement in the Middle Segment was
177,881 at Talkeetna Station (RM 103) and 116,858 at Curry Station (RM 120) which represent
approximately 5 percent and 3 percent of the estimated total Susitna Basin escapement at
Flathorn Station (RM 22), respectively (Jennings 1985). Escapement estimates at the Talkeetna
Station (RM 103) were considered to overestimate pink salmon abundance because many adult
pink tagged at that point returned downstream to spawn (Jennings 1985). Pink escapement
estimated at Sunshine Station (RM 80) in 1984 represented 28 percent of the total Susitna Basin
escapement, which indicates that most adult pink salmon utilize Lower River mainstem and
tributary habitats.
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5.1.2.5.1. Middle River
Adult pink salmon migration in the Middle River of the Susitna River during the 1980s occurred
from mid-July through mid-September and typically peaked during late July and early August
(Table 5.1-5) (Jennings 1985, Barrett et al. 1985, Thompson et al. 1986). Although milling and
holding behavior was observed by pink salmon in the Middle Segment near Talkeetna Station
(RM 103), it is not clear how long adult pink hold in main channel areas prior to migrating up
spawning tributaries (Barrett et al. 1985). Adult pink use main channel areas for passage to
primary spawning areas in tributaries and tributary mouths and secondary spawn sites in side
slough habitats (Jennings 1985).
Adult pink salmon spawning in the Middle River begins in late July and early August in clear
water tributaries and peaks during the first two weeks of August (Table 5.1-5) (Jennings 1985,
Thompson et al. 1986). A small portion (5 percent) of observed spawning occurred in side
slough areas; one main channel pink salmon spawning location was observed in 1984 (Jennings
1985, Barrett et al. 1985). The timing of spawning in side slough habitats is similar to that of
tributaries, though spawning peaks later in August and can extend into early September (Table
5.1-5) (Jennings 1985). Indian River (RM 138.6), Portage Creek (RM 148.9), and 4th of July
Creek (RM 131.1) were the principal spawning tributaries that supported a large proportion of
the adult pink population in the Middle Segment during the 1980s (Jennings 1985). Among side
sloughs in the Middle Segment, most pink salmon spawning occurred in Slough 11 and Slough
20 (Jennings 1985).
The timing of pink salmon egg incubation and fry emergence on the Susitna River is not well
defined due to limited observations of this life stage, though the start of incubation is considered
to be coincident with spawn timing. In controlled environments, the duration of pink egg
incubation from the point of fertilization to hatch is approximately 173 days (Murray and
McPhail 1988). In the Susitna River, emergent pink salmon fry were observed in spawning areas
in Indian River (RM 138.6) and Slough 11 (RM 135.3) during late March and early April
(Delaney et al. 1981). Based on these observations of pink fry emergence timing and general life
history requirements, emergence of pink salmon fry is estimated to occur during March and
April (Table 5.1-5) (Delaney et al. 1981a, Jennings 1985). Differences in egg incubation and fry
emergence timing may occur, however, between side slough spawning areas influenced by
groundwater upwelling and tributary spawning habitats fed primarily by surface streamflows
(Wangaard and Burger 1983, Vining et al. 1985).
Juvenile pink salmon in the Susitna Basin immigrate to estuarine and marine areas soon after
emergence as age-0+ fry and consequently exhibit minimal use of Susitna River nursery habitats
during the short freshwater residence (Jennings 1985). Migration of pink fry appeared to begin
prior to seasonal operation of mainstem outmigrant traps in the 1980s, and researchers during the
1980s considered it likely that many pink salmon fry in the Middle Segment migrated
downstream of the trap prior to the open water season and the start of trap operation (Jennings
1985, Roth et al. 1986, Roth and Stratton 1985). At a fyke net trap operated from April through
May 1985 in a Lower River side channel, pink salmon fry were initially captured in mid-May
(Bigler and Levesque 1985). Downstream migration of pink fry is estimated to begin in April
though sampling of downstream migrants in the Middle Segment was not done prior to May
during the 1980s due to instream ice conditions (Jennings 1985, Roth and Stratton 1985).
Outmigrant trapping during the 1980s at the Talkeetna Station (RM 103) indicated peak
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movement in the Middle River during late May and June (Table 5.1-5) (Jennings 1985, Roth et
al. 1986). Although migration timing varied during the 1980s studies, few juvenile pink were
captured after July (Jennings 1985). Habitat use during downstream is not well known in the
Susitna Basin and it is not clear that any feeding by age-0+ pink occurs while in the Susitna
River (Jennings 1985). In the Susitna River and other river systems, pink salmon utilize thalweg
portions of the river channel with faster current to migrate downstream and the rate of feeding
during freshwater residence often depends upon the length of migration (McDonald 1960, Roth
and Stratton 1985). In short coastal streams, pink salmon fry may not feed during freshwater
residence, while in larger rivers, where migration may last multiple days, pink fry may feed
exogenously (Heard 1991).
5.1.2.5.2. Lower River
Adult pink salmon migration in the Lower River of the Susitna River occurs from early July to
early September, though most adult pink movement was from mid-July to mid-August (Table
5.1-5) (Jennings 1985, Roth and Stratton 1985, Roth et al. 1986). Milling and holding behavior
among adult pink salmon upstream of the Chulitna River confluence (RM 98.6) was identified
during the 1980s, as fish tagged at the Talkeetna Station were observed spawning in Lower River
tributaries (Barrett et al. 1985). Despite these observations, it is not evident that there was a
substantial migratory delay for pink salmon adults between main channel and tributary areas
(Barrett et al. 1985, Thompson et al. 1986).
Adult pink salmon in the Lower River spawned in tributary and tributary mouth habitats during
1984 and 1985; no pink salmon spawning was observed in main channel or side slough habitats
in 1984 (Barrett et al. 1985, Thompson et al. 1986). Based on 1984 and 1985 surveys of Lower
River tributaries, pink spawn timing occurred from mid-July through early September and
peaked during early and mid-August (Table 5.1-5) (Barrett et al. 1985, Thompson et al. 1986).
The Talkeetna River (RM 97.2), Birch Creek (RM 88.4) and Willow Creek (RM 49.1) were
primary spawning tributaries for pink salmon during the 1980s (Barrett et al. 1985, Thompson et
al. 1986).
The periodicity of pink salmon egg incubation and fry emergence in the Lower River of the
Susitna River is similar to that described for the Middle Segment (see Section 3.6.1). Pink
salmon egg incubation occurs from late July through the estimated end of emergence in mid-May
(Table 5.1-5) (Jennings 1985). Emergence timing pink salmon fry likely occurs during March,
April and early May in the Susitna River, based on limited observations of emergent fry during
late winter (Delaney et al. 1981a).
Pink fry emigration in the Susitna River occurs soon after emergence and is similar to that
described for the Middle Segment. The approximate start of pink salmon fry migration is likely
during April based on observed timing of fry emergence in March and early April (Table 5.1-5)
(Delaney et al. 1981a). Though it is possible much of the pink salmon fry migration occurred
prior to the start of mainstem trap operation, capture records indicate that age-0+ pink movement
peaked during early or late June at the Flathorn Station trap (RM 22) in 1984 and 1985 and was
completed by mid- or late July (Roth and Stratton 1985, Roth et al. 1986). A difference in pink
salmon fry migration timing of approximately two weeks between 1984 and 1985 was attributed
to ice breakup, regional winter temperatures and adult spawn timing (Roth and Stratton 1985).
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5.1.2.6. Rainbow Trout
Rainbow trout in the Susitna River are distributed throughout tributary and mainstem areas
downstream of Devils Canyon (RM 150) (Schmidt et al. 1983). Comparison of 1982 capture
data indicated that adult rainbow trout are more abundant in the Middle Segment of the Susitna
River relative to the Lower River (Schmidt et al. 1983). Estimated abundance of rainbow trout
greater than 150 mm in length during the early 1980s in the Middle Segment was approximately
4,000 fish based on a tag-recapture study conducted during 1981–1983 (Sundet and Wenger
1984). The age range of rainbow trout captured during the 1980s was up to 9 years old and all
captured fish that were known to spawn were 5 years old or older (Sundet and Wenger 1984).
Adult rainbow trout in the Susitna Basin utilize clear, non-glacial tributary habitats to spawn
(Schmidt et al. 1983). Adult spawning migrations from main channel holding areas to spawning
tributaries began in March prior to ice breakup and continued through early June (Table 5.1-6)
(Schmidt et al. 1983, Suchanek et al. 1984b, Sundet 1986). Most rainbow trout spawning
occurred during late May and early June (Table 5.1-6) (Schmidt et al. 1983, Suchanek et al.
1984b, Sundet and Pechek 1985). Migration and spawn timing for rainbow trout appears to be
generally similar between Middle and Lower Susitna Segments, though it was noted that timing
of upstream migration into tributary habitats could occur as much as 10 days earlier in the Lower
River (Sundet and Pechek 1985). Primary spawning tributaries in the 1980s were 4th of July
Creek (RM 131.1) and Portage Creek (RM 148.9) in the Middle Segment and the Talkeetna
River (RM 97.2), Montana Creek (RM 77.0) and Kashwitna River (RM 61.0) in the Lower River
(Sundet and Pechek 1985).
After spawning, adults primarily hold and feed during the open water period in tributary and
tributary mouth habitats, though some utilization of clear side slough habitat was observed
during the 1980s (Table 5.1-6) (Schmidt et al. 1983). Holding and feeding areas during the open
water period were closely associated with salmon spawning areas (Chinook, chum and pink
salmon) (Sundet and Pechek 1985). Primary holding and feeding locations for rainbow trout
were 4th of July Creek (RM 131.1) and Indian River (RM 138.6) tributary mouths and Slough 8A
(RM 125.1) and Whiskers Creek Slough (RM 101.2) (Schmidt et al. 1983).
During late summer in 1983 and 1984, adult rainbow trout migrated from tributary habitats
during late August and September, such that many individuals had moved to tributary mouths by
mid-September and few remained in tributaries by early October (Suchanek et al. 1984b, Sundet
and Wenger 1984, Sundet and Pechek 1985). Migration timing to winter holding areas in main
channel and side channel areas occurred from mid-September through early February, with peak
movement in October and late December (Schmidt and Estes 1983, Sundet 1986). In the Middle
Segment, rainbow trout utilize main channel areas during winter, whereas tagged fish in the
Lower River were observed to typically use side channel habitat during the 1980s (Sundet and
Pechek 1985). By December, most adult rainbow trout were in main channel areas apart from
spawning tributaries (Sundet and Wenger 1984). Movements to winter holding habitats were
commonly in a downstream direction from spawning or feeding tributaries (Sundet and Pechek
1985). Many adults hold during winter close to spawning tributaries (0.1 – 4 miles), though
some exhibit long-distance migrations that typically range from 10-20 miles downstream but can
extend over 76 miles (Schmidt and Estes 1983, Sundet 1986). Specific habitat features of winter
holding areas during the 1980s were difficult to measure, though upwelling and ice cover
appeared to be common features (Schmidt et al. 1983, Sundet and Pechek 1985). Tagged
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rainbow trout distribution in winter was patchy and groups of fish were often observed within
100 feet of an open water lead during winter, suggesting that ice cover was important in addition
to the presence of upwelling (Sundet and Pechek 1985, Sundet 1986). No radio tagged fish were
observed in areas with anchor ice during radio telemetry studies in the 1980s (Sundet 1986).
There is minimal information relating to rainbow trout incubation and emergence timing in the
Susitna River from studies conducted in the 1980s; however, incubation is assumed to begin in
May based on observed spawn timing (Table 5.1-6) (Schmidt et al. 1983, Suchanek et al. 1984b,
Sundet and Pechek 1985). The start of rainbow trout fry emergence in tributary habitats is
estimated to occur in early July and continue through mid-August based on generalized
incubation times for rainbow trout in cold water temperature regimes (5-8° C) (Crisp 1988,
Quinn 2005).
Juvenile rainbow trout primarily reside in natal tributary habitats throughout the year, though
occasional use of tributary mouths and clear sloughs has been documented (Table 5.1-6)
(Schmidt et al. 1983). Capture of juvenile rainbow trout in main channel areas was very low,
though use of tributary mouths and clear sloughs was observed (Sundet and Pechek 1985). Lake
systems associated with the 4th of July and Portage creeks were believed to possibly supplement
rainbow trout production in each basin based on analysis of juvenile scale patterns, though no
direct evidence of juvenile rearing in these lakes was recorded (Sundet and Pechek 1985).
Winter rearing for juvenile rainbow trout occurred primarily in tributaries with occasional use of
clear side slough habitats (Schmidt et al. 1983).
5.1.2.7. Arctic Grayling
Arctic grayling occur throughout the Susitna River Basin in mainstem and tributary habitats from
headwater areas in the Upper River to the downstream extent of the Lower River (Delaney et al.
1981b, Buckwalter 2011). Estimated grayling abundance was higher in the Upper River of the
Susitna River relative to the Middle and Lower segments based on 1980s mark-recapture data,
though comparable abundance data among segments are limited (Delaney et al. 1981b, Delaney
et al. 1981c, Schmidt et al. 1983). Estimated abundance of Arctic grayling greater than 200 mm
fork length in the Upper River was 10, 279 (95% confidence interval: 9,194 – 11,654) based on
1981 mark-recapture data, and was 6,783 (95% confidence interval: 4,070 – 15,152) in the
Middle Segment based on 1981-1984 data (Delaney et al. 1981b, Sundet and Pechek 1985).
Grayling of 200 mm fork length or greater are typically 3 years of age or older, while the
maximum observed age of grayling in the Susitna Basin during the 1980s was 15 years (Delaney
et al. 1981b, Schmidt et al. 1983). Sexual maturation of Arctic grayling in Alaska occurs
between ages 2 – 7; male and female grayling spawners during 1984 in the Susitna Basin were
aged 5 to 9 years (Sautner and Stratton 1984).
Adult grayling typically spawn in the upper extents of clear, non-glacial tributaries soon after ice
breakup, though use of areas near tributary mouths for spawning was recorded during 1980s
studies (Sundet and Wenger 1984). The spring spawning migration occurs concurrently with
increasing tributary water temperatures during April and May and movement of some large
adults into ice-free tributaries occurred prior to or during ice breakup (Table 5.1-7) (Sundet and
Wenger 1984, Sundet and Pechek 1985). Spawning typically occurs in May and early June,
though timing can vary among tributary habitats (Table 5.1-7) (Sundet and Wenger 1984, Sundet
and Pechek 1985). Spawning occurred in early May near the mouth of Whiskers Creek, in late
May near the Portage Creek tributary mouth, while large numbers of adult grayling in the upper
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extent of Portage Creek in early to mid-June 1984 may suggest spawning occurred in June in
headwater habitats (Sundet and Pechek 1985). Adult grayling movement and spawn timing
differed up to 10 days among Middle Segment tributaries and up to 20 days between tributaries
in the Middle and Lower segments due to variable tributary water temperature during May and
June (Sundet and Wenger 1984, Sundet and Pechek 1985).
During the open water season, many adult grayling either remain within spawning tributaries or
move to nearby tributaries to feed during summer (Table 5.1-7) (Delaney et al. 1981b, Delaney
et al. 1981c, Schmidt et al. 1983, Sundet and Pechek 1985). Adult grayling also use tributary
mouth, side slough and main channel habitats during the open water season, though fish captured
in these areas were typically of smaller size than adult grayling in tributaries which may suggest
that small individuals are displaced from tributaries by larger, competitively superior fish
(Schmidt et al. 1983, Sundet and Pechek 1985).
Adult grayling disperse from tributaries during early August through early October to winter
holding habitats (Table 5.1-7) (Sundet and Wenger 1984, Sundet and Pechek 1985). Although
many grayling use areas close to spawning tributaries during winter, some migrate long distances
(10-35 miles) to winter holding habitat (Sundet and Pechek 1985, Sundet 1986). Winter habitat
use of Arctic grayling in the mainstem Susitna River is not well understood, but limited radio
telemetry data suggests that grayling and other resident fish species may be patchily distributed
in main channel areas with overhead cover (depth and/or ice cover), very little frazil and/or
anchor ice, and low water velocity (Sundet 1986). Some grayling select lake habitats associated
with some tributary stream networks or deep pools located in larger tributaries in the Middle and
Lower segments (Sundet and Wenger 1984, Sautner and Stratton 1984).
Incubation time for Arctic grayling eggs is generally 11 to 21 days from fertilization to hatching,
depending on water temperature conditions, and young grayling actively feed within eight days
of hatching (Morrow 1980). Based on this general timing, the grayling egg incubation is
estimated to occur during May and June, and fry emergence likely during late May and June
(Table 5.1-7).
Juvenile Arctic grayling typically reside within their natal tributaries for at least one year, though
some age-0+ grayling were observed to move to tributary mouth habitats during late summer
(Schmidt et al. 1983). Ages-1+ and 2+ grayling were observed to use tributary mouth, side
slough and main channel habitats during summer 1982, and many were likely displaced from
tributary nursery habitats by larger, competitively superior adult grayling in early summer
(Schmidt et al. 1983). In general, juvenile grayling were recorded in greater abundance at
tributary mouths and mixing zones at side slough mouths relative to main channel areas
(Suchanek et al. 1984b). Tributaries in the Susitna Basin that support substantial Arctic grayling
populations include Oshetna River (RM 233.4), Kosina Creek (RM 206.8), Portage Creek (RM
148.9), Indian River (RM 138.6), Montana Creek (RM 77.0), Kashwitna River (RM 61.0) and
Deshka River (RM 40.6) (Delaney et al. 1981b, 1981c, Sundet and Pechek 1985).
5.1.2.8. Burbot
Burbot are distributed throughout the Susitna Basin and have been documented in mainstem
habitats upstream of the Upper River to the downstream extent of the Lower River (Delaney et
al. 1981b, Buckwalter 2011). During 1980s studies, burbot were most abundant in the Lower
River of the Susitna River relative to the Middle and Upper River, presumably because of greater
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spawning and nursery habitat availability (Schmidt et al. 1983, Sundet and Pechek 1985).
Burbot typically become sexually mature at age three or four, and were found as old as 15 years
in the Susitna River during 1980s studies (Scott and Crossman 1973, Schmidt et al. 1983, Sundet
and Pechek 1985).
Adult burbot exhibit strong negative phototropism and are strongly associated with turbid water
areas (Morrow 1980, Schmidt et al. 1983, Sundet and Pechek 1985). During the open water
season, burbot were typically captured in low velocity backwater or eddy habitats located in the
Susitna River main channel and at the mouths of select tributaries and side sloughs (Delaney et
al. 1981b, Schmidt et al. 1983, Sundet and Pechek 1985). Although burbot were also located in
shallow, high velocity habitats, the presence of groundwater upwelling appeared to have been a
common feature of habitats used by adult burbot during the 1980s (Sundet and Pechek 1985). A
small number of burbot were recorded in lake habitats in the Upper River of the Susitna River
during the 1980s (Sautner and Stratton 1984). During summer, adult burbot movement appears
to be infrequent and over short distances, based on radio telemetry and Floy tag-recapture studies
during the 1980s (Sundet and Wenger 1984).
In late summer, adult burbot begin migration to spawning locations in tributaries, tributary
mouths and main channel habitats based on 1980s radio telemetry data (Schmidt and Estes 1983,
Sundet 1986). Spawning migrations begin in mid-August to Lower River spawning tributaries
and in September to main channel areas and movement continues through winter until spawning
(Table 5.1-8) (Schmidt and Estes 1983, Sundet 1986). Burbot spawning migrations generally
range from 5 – 40 miles in length, though one tagged individual during the 1980s may have
migrated over 100 miles to a Lower River spawn site (Schmidt and Estes 1983). Spawning
occurs from mid-January to early February in tributaries, tributary mouths and main channel
habitats (Table 5.1-8) (Schmidt and Estes 1983, Sundet and Pechek 1985). Substantial spawning
runs occurred in Alexander Creek (RM 10.1) and the Deshka River (RM 40.6) (Sundet and
Wenger 1984, Sundet and Pechek 1985). Identification of Susitna River main channel spawn
sites was difficult during the 1980s due to thick ice cover during the January and February spawn
period, though observations of radio tagged burbot winter locations suggest that spawning may
occur in low velocity habitats with groundwater presence and ice cover (Schmidt and Estes 1983,
Sundet 1986). Burbot are typically group spawners, and multiple observations of burbot at the
location of radio tagged burbot during late winter suggest that adults congregate during winter
(Schmidt and Estes 1983). The prevalence of anchor ice in the Middle Segment may limit
burbot spawning success and overall abundance in this portion of the Susitna River (Sundet and
Pechek 1985). Post-spawning migrations occur from February through March and are typically
short (0.5 – 7 miles) (Table 5.1-8) (Schmidt and Estes 1983).
Incubation and development of burbot eggs is not well documented in the Susitna River due to
difficulty of sampling ice covered spawning sites during winter (Sundet and Pechek 1985).
Burbot eggs may be initially neutrally buoyant following spawning, but gradually sink and
become lodged within the substrate during development (McPhail and Paragamian 2000). The
necessary time for burbot egg incubation may require 30 days at incubation temperatures of 6°C,
71 days at water temperatures below 2°C, and approximately 100 days or more at near 0°C
temperatures (Bjorn 1940, McCrimmon 1959, McPhail and Paragamian 2000). Based on these
data, burbot egg incubation is estimated to occur from mid-January through April (Table 5.1-8).
Upon hatching, burbot fry are small (3-4 mm, total length), limnetic and drift passively until
swimming ability and mobility improves (McPhail and Paragamian 2000). As such, emergence
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timing is not identified for juvenile burbot. Small age-0+ fry (15 mm, total length) were
observed in mid-June in the Middle and Lower segments during 1980s studies (Sundet and
Pechek 1985).
Juvenile burbot were infrequently captured in association with 1980s sampling efforts (Sundet
and Pechek 1985). In the Lower River, juvenile burbot were captured in main channel and
tributary habitats, and it was believed that juveniles in tributaries utilized habitats proximal to
natal areas (Table 5.1-8) (Schmidt et al. 1983). Most juvenile burbot capture occurred at main
channel outmigrant traps during the 1980s, though positioning of outmigrant traps near the
surface of the water column did not effectively sample benthic movements of juvenile burbot
(Schmidt et al. 1983).
5.1.2.9. Round Whitefish
Round whitefish are distributed among mainstem and tributary habitats in the Upper, Middle and
Lower segments of the Susitna Basin, and have been recorded in mainstem areas upstream of the
Upper River to RM 19 (Schmidt et al. 1983, Buckwalter 2011). Based on 1980s studies
downstream of Devils Canyon (RM 150), round whitefish were more abundant in the Middle
Segment compared to the Lower River, and relative use was particularly high between RM 132 –
RM 151 (Sundet and Pechek 1985). The estimated population size of round whitefish in the
Middle Segment in 1983 was 7,264 (95% confidence interval: 4,829 – 13,806) (Sundet and
Pechek 1985). Within the Lower River, most adult round whitefish were captured between RM
60.1 and RM 98.5 (Sundet and Pechek 1985). Spawning round whitefish during 1980s studies
were age 5 or older, and the maximum age observed was 12 years (Sundet and Wenger 1984,
Sundet and Pechek 1985).
Adult round whitefish in the Susitna River Basin predominantly used tributary, tributary mouth
and sloughs for feeding and holding habitat during the open water season during the 1980s
(Sautner and Stratton 1983, Schmidt et al. 1983, Sundet and Wenger 1984, Sundet and Pechek
1985). Tributary sampling indicated that many large adult round whitefish moved upstream into
large clear tributaries in the Middle Segment in June and returned downstream to mainstem areas
in August and September (Table 5.1-9) (Schmidt et al. 1983, Sundet and Wenger 1984). Low
capture rates of small adults in tributaries during summer may suggest that smaller individuals
were competitively displaced by large adults (Schmidt et al. 1983).
During tag-recapture studies in the 1980s, most recaptured adult round whitefish exhibited little
movement, though approximately 20% of recovered fish in 1983 and 1984 had moved an
average of 18.5 and 16 miles in the respective years (Sundet and Wenger 1984, Sundet and
Pechek 1985). Maximum observed movement of tagged round whitefish was 55.7 miles based
on 1983 recapture data and 69.5 miles based on 1984 tag recaptures (Sundet and Wenger 1984,
Sundet and Pechek 1985). Movement was typically downstream during summer and upstream in
fall (Sundet and Wenger 1984).
In late summer, adult round whitefish migrate upstream and downstream from summer feeding
habitats to spawning areas located in main channel and tributary mouth habitats, though large
schools observed at the mouths of Portage Creek (RM 148.8) and Indian River (RM 138.6) may
indicate tributary spawning (Schmidt et al. 1983, Sundet and Wenger 1984). Based on fishwheel
capture in 1982 and 1983, upstream spawning migration in the main channel of the Middle
Segment occurred during late August and September (Table 5.1-9) (Schmidt et al. 1983, Sundet
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and Wenger 1984). Round whitefish spawning in the Susitna Basin was believed to occur during
October (Table 5.1-9) (Sundet and Wenger 1984, Sundet and Pechek 1985). Spawning sites
discovered in 1983 consisted of four main channel sites (RM 102.0, RM 114.0, RM 142.0 and
RM 147.0) and three tributary mouth sites [Lane Creek (RM 113.6), Indian River (RM 138.6)
and Portage Creek (148.8)] (Sundet and Wenger 1984). Most sexually ripe adults were captured
in pairs or small groups during the 1980s and capture locations were characterized as spawning
sites if captured females discharged eggs via palpation (Sundet and Wenger 1984). After
spawning, it is believed that adult round whitefish utilized mainstem areas to hold for winter, but
little is known regarding winter behavior and habitat use (Sundet and Pechek 1985).
The duration of round whitefish egg incubation and timing of fry emergence in the Susitna River
is not well defined by 1980s studies. Development and incubation time for round whitefish eggs
has been observed to take approximately 140 days at 2.2° C, though duration can vary with water
temperature and other variables (Normandeau 1969, Morrow 1980). Based on this basic
incubation period and the timing of earliest age-0+ round whitefish capture in late May and June,
incubation is estimated to occur from October through June and emergence likely occurs in May
and June (Table 5.1-9) (Schmidt et al. 1983).
Age-0+ juvenile round whitefish are believed to utilize nursery habitats proximal to where
hatching and emergence occurs, though a portion of the Middle Segment population migrated
downstream in each year of 1982 and 1983 (Schmidt et al. 1983, Sundet and Wenger 1984).
Downstream movement of juvenile round whitefish at the Talkeetna Station (RM 103)
outmigrant trap occurred throughout the trap operational period in each year, from late May
through September, and peaked in late June and July (Table 5.1-9) (Schmidt et al. 1983, Sundet
and Wenger 1984). Following downstream movement, primary habitats used by juvenile round
whitefish in the Middle and Lower segments were side slough, upland slough and turbid main
channel and side channel areas (Schmidt et al. 1983, Sundet and Wenger 1984). In the Upper
River, juvenile round whitefish were captured at tributary mouths and slough habitats (Sautner
and Stratton 1983). Juvenile round whitefish may utilize turbid mainstem areas for cover
(Suchanek et al. 1984b). Little is known regarding juvenile round whitefish habitat use during
the winter, but based on spring capture locations during the 1980s, it was presumed that winter
nursery habitats were proximal to summer habitats (Sundet and Pechek 1985).
5.1.2.10. Humpback Whitefish
Humpback whitefish are distributed throughout the Susitna Basin and have been documented
from mainstem habitats upstream of the Upper River to the downstream extent of the Lower
River (Schmidt et al. 1983, Buckwalter 2011). Sampling during the 1980s indicated that
abundance of humpback whitefish was greater in the Lower River of the Susitna River relative to
the Middle Segment (Schmidt et al. 1983, Sundet and Wenger 1984). Abundance estimates of
humpback whitefish were not possible during the 1980s studies due to an insufficient number of
fish captured for mark-recapture estimation. Humpback whitefish typically mature at age 4 to 6
and individuals up to 12 years of age were captured in the Susitna River during the 1980s
(Morrow 1980; Schmidt et al. 1983, Sundet and Wenger 1984).
Humpback whitefish populations in Alaska are typically anadromous, though the marine
distribution and the distance individuals disperse from natal rivers is not well known (Morrow
1980). In the Susitna River, a portion of the population may utilize estuarine or marine habitats
for a portion of their lifespan, while most humpback whitefish appear to exhibit a riverine life
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history pattern based on analysis of adult scale patterns (Sundet and Wenger 1984, Sundet and
Pechek 1985). High growth rates during the first two years of life, which may indicate estuarine
feeding, were apparent in approximately 20% of adult humpback whitefish captured at Lower
River fishwheel traps (Flathorn Station [RM 22], Yentna River Station [Yentna RM 4]) and
about 5% of adults captured at the Talkeetna Station (RM 103) fishwheel in the Middle Segment
(Sundet and Pechek 1985).
Adult humpback whitefish exhibited higher relative use of tributary and slough habitats for
holding and feeding in summer relative to mainstem areas during studies conducted in the
Middle and Lower segments during 1981-1983 (Sundet and Wenger 1984). Just one adult
humpback whitefish was captured in the Upper River during 1980s studies at a tributary mouth
(Sautner and Stratton 1983). In general, adult humpback whitefish exhibit little movement
during summer except for spawn migrations, which in the Susitna River is an upstream migration
that occurs from July through September, with peak movement during August (Table 5.1-10)
(Morrow 1980, Schmidt et al. 1983, Sundet and Wenger 1984). Spawning is believed to occur
during October in tributaries of the Susitna River, based on high capture of adults in tributaries
during fall, but is not well documented (Table 5.1-10) (Sundet and Pechek 1985). Adult
humpback whitefish captured in Deadman Lake in the Upper River were presumed to spawn
within the lake (Sautner and Stratton 1984). Alaskan humpback whitefish populations utilize
estuarine habitat during winter, though in the Susitna River adult humpback whitefish is largely
unknown due to low winter capture rates during winter sampling (Morrow 1980, Schmidt et al.
1983). Humpback whitefish in the Middle Segment were believed to remain in that segment
during winter (Sundet and Pechek 1985).
Incubation and development timing of humpback whitefish eggs is not well known, though it is
presumed hatching occurs in late winter and spring (Morrow 1980). The period of humpback
whitefish egg incubation is estimated to occur from the start of spawning in early October
through June (Table 5.1-10). Emergence of humpback whitefish fry started prior to June during
1980s studies based on outmigrant trap capture records (Schmidt et al. 1983, Sundet and Wenger
1984). Humpback whitefish are estimated to emerge from early May through late June (Table
5.1-10).
Juvenile humpback whitefish rearing was believed to primarily occur in the Lower River in the
Susitna River during the 1980s, though specific nursery habitat use was not well defined due to
low and infrequent capture (Schmidt et al. 1983, Sundet and Wenger 1984). The few juvenile
humpback whitefish were captured in tributary, main channel and side channel habitats (Schmidt
et al. 1983). Most capture of juvenile humpback whitefish during the 1980s studies occurred at
outmigrant traps. Downstream migration of juvenile humpback whitefish was observed to occur
from June through October at the Talkeetna Station (RM 103) outmigrant trap, with peak
movement during July and early August (Table 5.1-10) (Schmidt et al. 1983, Sundet and Wenger
1984). Approximately 20% of juvenile humpback whitefish in the Lower River and 5% in the
Middle Segment were believed to use estuarine areas during the first two years of life (Sundet
and Pechek 1985).
5.1.2.11. Longnose Sucker
Longnose suckers are distributed throughout mainstem habitats in Susitna Basin and have been
documented from headwater tributaries upstream of the Upper River to the downstream extent of
the Lower River (Delaney et al. 1981b, Buckwalter 2011). Longnose suckers were most
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abundant downstream of Devils Canyon (RM 150), particularly in the Lower River between RM
60 and RM 35 (Delaney et al. 1981b, Schmidt et al. 1983, Sundet and Pechek 1985). Estimated
population size of longnose sucker in the Middle Segment of the Susitna River was 7,613 (95%
confidence interval: 4,003 – 20,439) based on 1981-1984 mark-recapture data.
Adult longnose suckers in the Susitna Basin spawn in mainstem and tributary mouth habitats
during May and early June, which corresponds with the approximate timing of other Alaskan
sucker populations (Table 5.1-11) (Morrow 1980, Schmidt et al. 1983). An additional spawning
period may occur in the late summer during October and/or November based on observed
concentrations of adults with well-developed eggs and nuptial tubercles during September in
suitable spawning habitats, though spawning during this time has not been verified (Schmidt et
al. 1983, Sundet and Wenger 1984). Longnose sucker spawning typically occurs at water
temperatures above 5°C (Morrow 1980).
Following spring spawning, a portion of longnose suckers in the Susitna River appeared to move
upstream to summer feeding habitats and return downstream to winter holding areas, based on
1980s mark-recapture data (Sundet and Wenger 1984, Sundet and Pechek 1985). Spring
upstream movement of adult suckers primarily occurred during June and July, while the timing
of downstream fall movement was less defined (Table 5.1-11) (Schmidt et al. 1983, Sundet and
Wenger 1984). Many suckers tagged during 1980s studies moved little during summer, which
reflects summer behavior of other sucker populations (Morrow 1980, Sundet and Wenger 1984,
Sundet and Pechek 1985). Adult suckers were most commonly captured at tributary and slough
sites, though use of mainstem habitat was greater in the Middle Segment relative to that of the
Lower River (Schmidt et al. 1983, Sundet and Wenger 1984, Sundet and Pechek 1985). High
capture rates of adults in tributaries and sloughs in August and September may indicate
opportunistic feeding on salmon eggs during this time (Sundet and Wenger 1984). In the Upper
River, only sub-adult suckers were captured in mainstem habitats, while larger adults were
captured at the mouths of suspected spawning tributaries (Sautner and Stratton 1983). Habitat
utilization by adult longnose suckers during winter in the Susitna River is not well known,
though winter holding is believed to occur in the mainstem and the only winter capture of a
longnose sucker occurred in side channel habitat (Schmidt and Bingham 1983, Schmidt et al.
1983).
Incubation and development of longnose sucker eggs in the Susitna River has not been
documented, however, general incubation time required from fertilization to hatching is one to
two weeks and newly hatched fry may remain in the gravel for an additional two weeks prior to
emerging (Morrow 1980). Timing of longnose sucker egg incubation is estimated to occur from
early May to mid-July based on this information (Table 5.1-11). Fry emergence likely occurs
during June and early July (Table 5.1-11).
Juvenile longnose sucker fry typically drift from natal sites following emergence to summer
nursery areas (Morrow 1980). Suckers in the Susitna River appear to exhibit this early life
history strategy, though it is not clear to what extent such dispersal occurs based on low catch at
outmigrant traps at Talkeetna Station (RM 103) (Schmidt et al. 1983). Age-0+ downstream
movement in the Middle Segment occurred throughout the open water period in 1982 and 1983,
and exhibited a bi-modal peak during June and during late August and September, based on
outmigrant traps in the Susitna River main channel and Deshka River (Table 5.1-11) (Schmidt et
al. 1983, Sundet and Wenger 1984, Sundet and Pechek 1985). Summer nursery habitats used by
juvenile longnose in the Susitna River during the 1980s were side channels, upland sloughs, side
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sloughs and to a lesser extent, tributary mouths (Schmidt et al. 1983, Sundet and Wenger 1984).
Winter habitat use by juvenile suckers is not known (Schmidt et al. 1983). Shallow depth, low
water velocity and turbidity or structural (i.e., aquatic or overhead vegetation) cover are
considered important characteristics for juvenile longnose nursery habitat (Suchanek et al.
1984b).
5.1.2.12. Dolly Varden
Dolly Varden are widely distributed within the Susitna Basin, from headwater tributaries to the
downstream extent of the Lower River (Schmidt et al. 1983, Buckwalter 2011). Estimation of
relative abundance of Dolly Varden among the Upper, Middle, and/or Lower segments was not
possible during 1980s studies due to low capture rates at sampling sites, though abundance of
Dolly Varden downstream of Devils Canyon appeared to be lower relative to upstream
populations (Schmidt et al. 1983, Sundet and Wenger 1984). The geographic ranges of the small
northern and larger southern forms of Dolly Varden overlap in then Susitna River (Morrow
1980). Adult Dolly Varden of the southern form become sexually mature at 4 to 6 years of age,
while maturity occurs between 7 to 9 years in the northern form (Morrow 1980).
Life history patterns of Dolly Varden can be complex and variable among habitats (Morrow
1980). General life history patterns exhibited by the southern form of Dolly Varden include
amphidromous populations that spawn in stream habitat and migrate to marine areas for a portion
of their life, adfluvial populations that are stream spawners but use lakes associated with natal
streams for nursery and holding habitat, fluvial Dolly Varden that migrate among stream
habitats, and stream resident populations that reside entirely within natal riverine habitats during
their life cycle (Morrow 1980). The extent to which each life history pattern is present in the
Susitna River isn’t clear, though adfluvial, fluvial and stream resident populations were apparent
during 1980s studies (Sautner and Stratton 1983, Schmidt et al. 1983, Sautner and Stratton
1984). Stream resident populations present in headwater areas of Susitna River tributaries were
of substantially smaller size than adfluvial and fluvial populations, though comparison of
morphological features among disparately-sized individuals indicated each was of the same
species (Sautner and Stratton 1983, Schmidt et al. 1983, Sautner and Stratton 1984).
Adult Dolly Varden primarily reside within tributary habitats during the open water season,
though apparent adfluvial populations were observed to use lakes to feed during summer
(Sautner and Stratton 1983, Sundet and Wenger 1984, Sautner and Stratton 1984). Movement
into tributaries occurred in June and July during 1980s studies, coincident with the timing of
upstream spawning migrations of adult Chinook salmon (Table 5.1-12) (Delaney et al. 1981b).
Adult Dolly Varden are believed to spawn in the upstream extents of clear tributaries during late
September and October based on a small number of observations of spawning behavior and
sexually ripe individuals (Table 5.1-12) (Delaney et al. 1981b, Schmidt et al. 1983, Sautner and
Stratton 1984). Primary tributary habitats in the Susitna River during the 1980s were Deadman
Creek (RM 186.7) in the Upper River, Portage Creek (RM 148.9) and Indian River (RM 138.6)
in the Middle Segment, and the Kashwitna River (RM 61.0) in the Lower River (Delaney et al.
1981b, Schmidt et al. 1983). Fishwheel capture data at the Talkeetna Station (RM 103) in 1982
and mark-recapture data during 1982-1983 suggest upstream movement of adult Dolly Varden in
the main channel in spring and fall, which may represent spring movement to tributary feeding
areas and fall migration to spawning areas (Schmidt et al. 1983, Sundet and Wenger 1984).
Most adult Dolly Varden are believed to migrate downstream from tributaries during September
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and October to winter holding habitats in the Susitna River main channel, though little is known
regarding the timing of such movement or locations of winter rearing (Table 5.1-12) (Schmidt et
al. 1983, Sundet and Wenger 1984). Adfluvial populations likely utilize lacustrine habitats
during winter, though timing of movement from tributaries is not known (Sautner and Stratton
1984).
Dolly Varden egg incubation and development to hatching occurs over a period of approximately
130 days at 8.5°C, but may require up to approximately 240 days on the north slope of Alaska
(Blackett 1968, Yoshihara 1973, Morrow 1980). After hatching, pre-emergent fry remain in the
gravel for 60 – 70 days (Morrow 1980). Based on this information, Dolly Varden egg incubation
is estimated to occur from mid-September through late May, and fry emergence likely occurs
during April and May (Table 5.1-12).
Juvenile Dolly Varden in the Susitna Basin primarily utilize natal tributaries as summer and
winter nursery habitat, though juvenile use of lakes was observed during 1980s studies (Table
5.1-12) (Delaney et al. 1981b, Sautner and Stratton 1983, Sautner and Stratton 1984). Little is
known regarding possible seasonal differences in juvenile Dolly Varden habitat use because
capture rates were generally very low during 1980s studies (Delaney et al. 1981b, Schmidt et al.
1983, Suchanek et al. 1984b). Dolly Varden that use lake habitats are likely part of adfluvial
populations that disperse to lakes from natal tributaries (Sautner and Stratton 1984). Few
juvenile Dolly Varden were captured in main channel outmigrant traps in 1982 (n=7) and 1983
(n=7) and at tributary mouths in the Susitna River mainstem, suggesting that few juveniles use
mainstem habitat (Delaney et al. 1981b, Sundet and Wenger 1984, Schmidt et al. 1983). During
winter, it is possible that juvenile Dolly Varden move downstream within natal tributaries,
though there is no evidence that juveniles utilize mainstem habitat during winter (Schmidt et al.
1983). In headwater tributaries with adfluvial populations, juvenile Dolly Varden likely use
lacustrine habitats during winter (Sautner and Stratton 1984).
5.1.2.13. Bering Cisco
The ecology of Bering cisco in Alaska is not well understood. Most Bering cisco in Alaska
exhibit diadromy by dispersing to estuarine or marine habitats during winter, though some
populations appear to reside entirely within freshwater (Morrow 1980). In the Susitna River,
most Bering cisco appear to migrate to estuarine or marine areas as age-0+ fry, but the duration
of residence in saltwater habitats is not known (ADF&G 1983a, Jennings 1985). The known
distribution of Bering cisco in the Susitna Basin ranges from the 4th of July Creek confluence
(RM 131.1) downstream to Cook Inlet (ADF&G 1983a, Barrett et al. 1984). Cisco
predominantly used the Lower River during 1980s research; in 1984, a total of 361 adult Bering
cisco were captured at the Flathorn Station (RM 22) fishwheel, while 3 were captured at the
Talkeetna Station (RM 103) (Barrett et al. 1985). Age of Bering cisco captured at Susitna River
fishwheels ranged from 4 to 6 (Barrett et al. 1984).
Adult Bering cisco were captured at fishwheel traps but were never captured during other
summer or winter sampling in the Susitna River in 1982 (Schmidt et al. 1983). As a result, little
is known regarding adult Bering cisco macro-habitat utilization for holding and feeding and
periodicity of this life stage is not described here. Upstream spawning migrations of Bering
cisco in the Susitna River occurred from early August through October, though fishwheel
operation ended October 1 in 1982 and earlier in other years, so the end of migration is not well
defined (Table 5.1-13) (ADF&G 1983a). Migration appeared to peak in late September during
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1982 (Table 5.1-13) (ADF&G 1983a). Adult Bering cisco utilized mainstem areas for spawning
and large concentrations of spawners were observed in the Lower River between RM 85 – RM
75 during 1980s studies (ADF&G 1983a, Barrett et al. 1984). Spawning during 1982 and 1983
occurred during September and October, with peak activity in early October (Table 5.1-13)
(ADF&G 1983a, Barrett et al. 1984). No spawning was observed in the Middle Segment during
1981, 1982, or 1983 (ADF&G 1983a, Barrett et al. 1984).
Egg incubation and emergence timing is not well defined for Bering cisco populations. In
general, egg incubation of other cisco (e.g., arctic cisco) occurs through the winter and early
spring and fry hatch in the spring (Morrow 1980). Based on this general timing, Bering cisco
egg incubation is estimated to occur from early September through June and fry emergence is
presumed to occur in May and June (Table 5.1-13). Soon after emergence, cisco fry emigrate to
the estuarine environment to rear (Morrow 1980). Juvenile fry emigration from natal areas in the
Lower Susitna is estimated to occur from mid-May through mid-July (Table 5.1-13).
5.1.2.14. Eulachon
Eulachon in the Susitna Basin have been documented from RM 50 downstream to Cook Inlet
(Barrett et al. 1984, Vincent-Lang and Queral 1984). Eulachon in the Susitna River were
characterized during 1980s studies in terms of first and second runs (Vincent-Lang and Queral
1984). The approximate abundance of the first run eulachon during 1982 and 1983 was likely
several hundred thousand while the size of the second run was several million (Barrett et al.
1984, Jennings 1985).
Eulachon are an anadromous species that reside in marine areas for most of their life and spawn
in freshwater streams (Morrow 1980). In 1982 and 1983, adult eulachon were captured in the
downstream extent of the Susitna River Lower River during the first sampling event in mid-May;
ice conditions precluded sampling prior to early or mid-May in each year (Vincent-Lang and
Queral 1984). The first run of adult eulachon spawning migration was believed to begin in early
or mid-May and the second run was considered to start in early June (Table 5.1-14) (Vincent-
Lang and Queral 1984). Barrett et al. (1984) concluded that adult eulachon spawn within 5 days
of entering the Susitna River. Eulachon spawning during 1982 and 1983 occurred downstream
of RM 29 in marginal areas of the Susitna River mainstem (Vincent-Lang and Queral 1984).
Adult eulachon that spawned in the Lower River in 1982 were predominantly age-3+ adult fish
that immigrated to marine habitats as age-0+ fry (ADF&G 1983a).
Eulachon eggs, after extrusion from the female, float to the bottom and become attached to the
spawning substrate (Morrow 1980). At water temperatures between 4.4° C and 7.2° C, time
required to egg hatching occurs in 30 to 40 days (Morrow 1980). Based on this, eulachon egg
incubation is estimated to occur from early May through mid-July (Table 5.1-14). The hatched
larvae are not strong swimmers and remain close to the substrate (Morrow 1980). Soon after
hatching, young eulachon larvae passively migrate to estuarine areas where rearing occurs
(Morrow 1980). Juvenile migration in the Susitna River is estimated to start in early June and
continue through July (Table 5.1-14). All juvenile rearing occurs in estuarine and marine
environments (Morrow 1980).
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5.2. Susitna-Watana 2013-2014 Studies
The periodicity of fish habitat use in the Susitna will be described during 2013-2014 fish and
aquatic studies (see AEA 2012, Section 9). Studies in 2013-2014 will be conducted in each
Susitna River segment (Upper, Middle and Lower) and will target resident fishes, anadromous
salmonids, and the freshwater life stages of non-salmon anadromous species. Target species
proposed for 2013-2014 fish and aquatic studies include: Chinook, sockeye, chum, coho and
pink salmon, rainbow trout, Arctic grayling, burbot, round whitefish, humpback whitefish,
longnose sucker, Dolly Varden, Bering cisco, eulachon, northern pike, Pacific lamprey, and
Arctic lamprey. Proposed target species and methods for the 2013-2014 fish and aquatic studies
identified in the Revised Study Plan (RSP) (AEA 2012) will be finalized in association with
Technical Work Group (TWG) meetings during spring 2013.
Adult resident fish holding and feeding habitats during summer and winter will be identified
using fish tagging and tracking technologies (radio and Passive Integrated Transponder [PIT]
tags) and a variety of capture techniques (AEA 2012). Adult fish capture methods proposed for
2013-2014 studies include gillnets, seines, trotlines, hoop traps, and angling. Sampling will be
performed by meso-habitat type to discern periodicity of holding and feeding among resident
fish species. Spawning and other seasonal migrations exhibited by resident fish species will be
described based on radio telemetry and PIT tag monitoring.
Adult salmon migration timing will be monitored during 2013-2014 aquatic studies in based on
fishwheel operation in the Middle and Lower segments and using radio telemetry and PIT
tracking. Spawn timing and habitat utilization will be monitored using radio telemetry and PIT
tracking in conjunction with ground/boat and aerial spawning surveys. Movement of tagged fish
will occur at fixed stations and based on mobile aerial tracking (radio telemetry only).
The periodicity of egg incubation and emergence timing will be identified for salmon species
spawning in mainstem areas using fyke net and minnow trapping, electrofishing and seining in
areas of known spawning. Sampling will be performed bi-weekly to identify the period and peak
of emergence for each species. Snorkeling may also be used where appropriate. Outmigrant
traps (i.e., rotary screw traps) operated near tributary mouths in each segment will supplement
emergence timing observations.
Juvenile fry and smolt movement timing for all species was estimated during the 1980s based
primarily on capture at stationary downstream migrant traps operated in the Susitna River main
channel at Talkeetna (RM 103) and Flathorn (RM 22) stations. Fish capture data from 1980s
summer and winter sampling were used to supplement outmigrant trap data and to identity
habitat utilization of anadromous and resident fish species. Capture sites visited during the
1980s and 2000s were located in main channel, off-channel and tributary habitats between
Susitna River RM 233.4 and RM 7.1.
Periodicity information gathered during 2013-2014 will be instrumental for instream flow
studies. Descriptions of the temporal and spatial utilization of mainstem and tributary habitats in
the Susitna River by fish species and life stages and will be essential to evaluate potential effects
of Susitna River discharge fluctuations on fish communities. Fish spawning and egg incubation
are critical life history stages that are particularly sensitive to fluctuations in stream flow.
Moreover, rearing and holding conditions in main channel and off-channel habitats in the Susitna
River that are utilized by juvenile and adult fish can be transformed in response to changes in
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river discharge. During 2013–2014 instream flow studies, periodicity analyses will be used to
guide habitat-specific modeling and spatial and temporal habitat analyses. Target fish species for
instream flow analyses will be identified in association with TWG meetings during spring 2013.
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6. TECHNICAL MEMORANDUM – HABITAT SUITABILITY CURVE
DEVELOPMENT STUDIES FOR THE SUSITNA RIVER
Habitat suitability criteria (HSC) curves represent an assumed functional relationship between an
independent variable, such as depth, velocity, substrate, groundwater upwelling, turbidity, etc.,
and the response of a species life stage to a gradient of the independent variable (suitability). In
traditional instream flow studies and in particular those associated with the Instream Flow
Incremental Methodology (IFIM) (Bovee 1982), HSC curves for depth, velocity, substrate,
and/or cover are combined in a multiplicative fashion to rate the suitability of discrete areas of a
stream for use by a species and life stage of interest (e.g., spawning, fry, juvenile, and adult).
HSC curves typically serve as input into hydraulic and habitat models and translate hydraulic and
channel characteristics into measures of overall habitat suitability in the form of weighted usable
area (WUA), which is an index of habitat. Depending on the extent of data available, HSC
curves can be developed from the literature, or from physical and hydraulic measurements made
in the field in areas used by the species and life stages of interest (Bovee 1986).
This TM summarizes readily available HSC information that may be relevant to the Susitna-
Watana Instream Flow Study (IFS), with a primary focus on information collected during the
1980s Su-Hydro studies. However, other relevant (i.e., from Alaska) HSC data were also
compiled and presented, and as well, a summary of HSC efforts related to the current Susitna-
Watana IFS that were conducted in 2012 and are proposed for 2013-2014 are likewise presented.
6.1. Su-Hydro 1980s Studies
An extensive set of HSC curves were developed as part of the 1980s Su-Hydro instream flow
studies. These criteria were developed using a combination of site-specific data collected
through fish sampling and literature sources, and through refinement based on the professional
judgment of project biologists. Microhabitat data were collected for various species and life
stages of fish, reflective of a suite of different parameters influenced by, or potentially influenced
by, flow. These included water depth, water velocity, substrate, upwelling occurrence, turbidity,
and cover.
Spawning HSC for chum and sockeye salmon were developed from redd observations in sloughs
and side channels of the Middle Segment of the Susitna River (Vincent-Lang et al. 1984b). Data
collection sites were concentrated in areas used for hydraulic simulation modeling to maximize
the concomitant collection of utilization and availability data necessary for the evaluation of
preference. HSC for chum salmon were modified using limited preference data; however,
preference could not be incorporated for sockeye salmon. HSC for depth, velocity, and substrate
were developed from this effort. Additionally, modified HSC were developed for substrate that
reflected the presence or absence of upwelling. Spawning habitat utilization for Chinook, coho,
and pink salmon was evaluated in tributaries of the Middle Segment of the Susitna River
(Vincent-Lang et al. 1984a). Sufficient data were collected to develop depth, velocity, and
substrate HSC curves for Chinook salmon. However, observations for spawning coho and pink
salmon were insufficient to develop HSC. Instead, spawning HSC for these two species were
based solely on literature data and modified using qualitative field observations.
HSC for rearing juvenile salmon were developed for the habitat parameters of depth, velocity,
and cover used by juvenile Chinook, coho, sockeye, and chum salmon (Suchanek et al. 1984b).
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These HSC were developed based on field data collected at representative tributary, slough, and
side channel sites between the Chulitna River confluence and Devils Canyon (Middle Susitna
River) and were considered to be specific to this reach. In addition, if differences in habitat
utilization were apparent at varying turbidity levels, separate HSC were developed for turbid vs.
clear water conditions for those species with sufficient sample sizes (i.e., juvenile Chinook). A
subsequent effort used similar methods to verify the applicability of these juvenile salmon
rearing HSC curves for the Lower River downstream of the Chulitna River confluence
(Suchanek et al. 1985). Findings from this effort resulted in some modifications to HSC for use
in the Lower River.
HSC for resident fish species were developed based on data collected through electrofishing,
beach seining, and hook-and-line sampling in tributary mouths, tributaries, and sloughs of the
middle Susitna River (Suchanek et al. 1984a). Cover and velocity HSC were developed for adult
rainbow trout, arctic grayling, round whitefish, and longnose sucker. HSC for cover were
developed separately for turbid vs. clear water conditions. A single depth HSC was developed
for all of these species combined. Only round whitefish were collected in sufficient numbers to
develop separate HSC for juveniles.
The following sections provide additional details regarding the 1980s efforts to develop HSC
curves, including a description of methods, study sites, data analyses, and the resulting curve
sets. A summary of species, lifestage and habitat parameters for which HSC curves were
developed for the Middle and Lower Segments of the Susitna River is provided in Table 6.1-1.
These curves are presented exactly as reported in their respective source references and have not
been modified. Substrate curves are one exception; to allow comparability between 1980s
substrate curves and those from other studies, adjusted substrate codes (Table 6.1-2) were used to
standardize the curves for this habitat parameter. Because some substrate size classes
overlapped, these adjusted codes are not exact.
6.1.1. Methods
The 1980s data collection and HSC curves development were conducted during several different
studies, each targeting certain species and life stages. Thus, methods used to collect and develop
HSC curves are presented in the following section by study.
6.1.1.1. Chum and Sockeye Salmon Spawning (Vincent-Lang et al. 1984a)
Studies related to the development of HSC for spawning chum and sockeye salmon are described
by Vincent-Lang et al. (1984a). These studies were initiated in 1982 to collect measurements of
depth, velocity, substrate, and upwelling at redd sites and determine the behavioral responses of
spawning chum and sockeye salmon to the various levels of these habitat variables. However,
utilization data collected in 1982 were inadequate to fully develop HSC because low discharge
and flow conditions 1imited access of adult chum and sockeye salmon into study sites.
Additional utilization data were collected in 1983 which, when combined with 1982 data,
information from literature, and professional judgment of project biologists, were sufficient for
developing chum and sockeye salmon spawning HSC.
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6.1.1.1.1. Site Selection
Sites for the collection of utilization data in sloughs and side channels of the Middle Segment of
the Susitna River (Talkeetna to Devils Canyon reach) were selected based on the presence of
spawning salmon and the ability to observe their activities. Efforts were concentrated in areas of
sloughs (Sloughs 8A, 9, and 21) and side channels (Side Channels 21 and Upper 11) where
hydraulic simulation modeling data were being collected to maximize the collection of combined
utilization and availability data, thereby allowing for the evaluation of preference. Other sloughs
and side channels in the Middle Segment of the Susitna River were also surveyed for spawning
activity and, if present, selected as additional study sites to extend the utilization data base.
These non-modeled sites were Sloughs 9A, 11, 17, 20, and 22; habitat availability data were not
collected at these sites. Spawning utilization data for chum salmon were also collected in
tributary mouth habitat locations (Lane and Fourth of July creeks; Sandone et al. 1984). While
these data were not included in the development of formal HSC curves, Sandone et al. (1984) did
compare utilization in tributary mouth habitats with findings from slough and side channel
habitats. A list of sites and the number of redds where suitability data were collected in support
of HSC development are provided in Table 6.1-3.
6.1.1.1.2. Collection Methods
At each study site, spawning salmon were located by visual observation. Fish activities were
observed from the stream bank for 10 to 30 minutes to determine active redd locations prior to
entering the water for measurements. A redd was considered active if a female was observed to
fan the substrate at least twice and a male exhibiting aggressive or quivering behavior was
present during the observation period. Water depth and velocity measurements were collected at
the upstream end of each active redd with a topsetting wading rod and a Marsh McBirney or
Price AA meter. The general substrate composition of each redd pit was visually evaluated using
the size classifications listed in Table 6.1-2. The presence of upwelling in the vicinity of the
redd was assessed visually and the distance from the redd was noted. For redds within hydraulic
simulation modeling study sites, staff gage readings were recorded and used to estimate the flow
at the time of redd measurements based on rating curves presented by Quane et al. (1984). This
flow was then used to simulate available depth, velocity, and substrate data to evaluate
preference.
6.1.1.1.3. Data Analysis and HSC Curve Development
In developing HSC curves for chum and sockeye salmon spawning, Vincent-Lang et al. (1984a)
first arranged redd measurements (depth and velocity) as histograms using several different
incremental grouping methods. Each grouping method was used to create a unique utilization
curve and statistical methods were then applied to identify which utilization curve best
represented the data based on minimal variance, irregular fluctuations, and peakedness. Because
substrate data were not continuous, using different grouping methods for substrate was not
appropriate and the utilization data plot was treated as the best substrate utilization curve. For
depth, velocity, and substrate, the best utilization curve was evaluated in terms of availability
data (i.e., preference), published information, and/or the professional opinion of project
biologists familiar with middle Susitna River salmon stocks to develop suitability curves.
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6.1.1.2. Chinook, Coho, and Pink Salmon Spawning (Vincent-Lang et al. 1984b)
The 1980s studies related to the development of HSC for spawning Chinook, coho, and pink
salmon were described by Vincent-Lang et al. (1984b). For Chinook salmon, HSC were
developed based on utilization data for the habitat variables of depth, velocity, and substrate
composition at spawning sites in selected tributaries of the Middle Segment of the Susitna River.
These data were modified using statistical methods and the professional judgments of project
biologists familiar with Susitna River Chinook salmon stocks to develop suitability criteria for
Chinook salmon spawning in tributaries of the Middle Segment. Suitability criteria were also
developed for coho and pink salmon spawning in tributaries of the Middle Segment based on
literature information as modified using the professional judgments of project biologists familiar
with the Susitna River coho and pink salmon stocks.
6.1.1.2.1. Site Selection
Out of 11 tributaries surveyed in the Middle Segment of the Susitna River, four tributaries
(Portage Creek, Indian River, Fourth of July Creek, and Cheechako Creek) were found to
support relatively high levels of Chinook salmon spawning and were therefore selected for
collection of Chinook salmon spawning utilization data. These four tributaries supported more
than 98% of the 1983 Chinook salmon spawning in the Middle Segment of the Susitna River,
with the majority occurring in Portage and Indian Creeks. These four tributaries also supported
more than 97% of the pink salmon spawning and more than 70% of the coho salmon spawning in
tributaries of the middle reach of the Susitna River (Barrett et al. 1983). Within the selected
tributaries, specific sites were chosen from helicopter reconnaissance that had high
concentrations of fish and were conducive to the deployment of field personnel. A list of sites
and the number of redds where suitability data were collected in support of HSC development
are provided in Table 6.1-3.
6.1.1.2.2. Collection Methods
Data collection efforts were timed to coincide with peak Chinook salmon spawning activity in
selected tributaries, which occurred from July 10 to August 20, 1983. Spawning salmon were
located in each study stream by visual observation and the same methods described by Vincent-
Lang et al. (1984b) for collecting chum and sockeye spawning utilization were used.
6.1.1.2.3. Data Analysis and HSC Curve Development
For Chinook salmon spawning, sufficient data were collected to develop HSC using utilization
data collected at redds in tributaries to the Middle Segment of the Susitna River. Analytical
methods were similar to those used for chum and sockeye salmon spawning summarized above
and described by Vincent-Lang et al. (1984a) and Vincent-Lang et al. (1984b). Utilization data
for coho and pink salmon spawning were insufficient to develop HSC. Curves for these two
species were instead derived from previously published information, as modified using the
opinion of field biologists familiar with Susitna River salmon stocks.
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6.1.1.3. Juvenile Salmon Rearing in the Middle Susitna River (Suchanek et al. 1984a)
Studies related to the development of HSC for juvenile salmon rearing in the Middle Segment of
the Susitna River are described by Suchanek et al. (1984a). These studies were conducted to
support evaluations of the effects of changes in Susitna River flow regimes on habitat used by
rearing juvenile salmon. In order to model changes in habitat usability, data were collected for
development of suitability criteria for the habitat attributes of cover, velocity, and depth used by
juvenile Chinook, coho, sockeye, and chum salmon based on representative sites between the
Chulitna River confluence and Devils Canyon.
6.1.1.3.1. Site Selection
Locations selected for sampling in 1983 for this effort had substantial numbers of rearing
juvenile salmon during previous studies in 1981 and 1982 or were thought to be typical sites
having the potential for juvenile rearing. Sites were located in the Middle Segment of the
Susitna River between Whiskers Creek (RM 101.2) and Portage Creek (RM 148.8). Seven
tributary sites, two upland sloughs, and 12 other sites characterized as side sloughs or side
channels (depending on mainstem flows) were sampled at least four times. Nine additional sites
were sampled only once and five sites were sampled two or three times. These additional sites
were chosen to represent a wider cross section of habitat conditions experienced by rearing
juvenile salmon in this reach of the Susitna River in addition to the intensive sampling in
tributaries, upland sloughs, side sloughs, and side channels. Limited sampling was done in the
mainstem channel and large side channels because of the difficulty in sampling these areas and
because high velocities in these areas was thought to limit juvenile rearing.
6.1.1.3.2. Collection Methods
Sampling was conducted during 8- to 10-day field efforts, twice monthly between May and
October, 1983. Twenty-three sites were sampled from three to seven times while 12 other sites
were only incidentally sampled on one or two occasions. Approximately eight staked transects
from 75 to 200 feet apart were established across each study site. Sampling cells 50 feet long by
six feet wide (300 ft2) were delineated upstream from each transect along each shoreline and
another mid-channel cell was located between shoreline cells. Transects were placed to
maximize the within-site variability of habitat types sampled while also attempting to maintain
uniform physical habitat within individual sampling cells. Cells were selected to represent a
wide range of habitat types; approximately 20 cells were sampled per day.
Sampling effort was targeted at sites where rearing fish were numerous based on knowledge of
seasonal movements. Sampling frequency was reduced if efforts to catch 30 or more juveniles of
a species in a grid of transects were unsuccessful. Backpack electrofishing units and 1/8" mesh
beach seines were used to sample cells in their entirety. Beach seining was typically limited to
turbid water areas whereas electrofishing was used in clear water areas. Electrofishing was the
preferred sampling method, but was found to be ineffective in turbid water. Each captured fish
was identified to species and measured for total length.
After sampling for fish, a set of habitat parameters for each cell was measured even if no fish
were captured. The average depth and velocity was measured and the total amount of available
cover (expressed in percent areal coverage) and dominant cover type was estimated for each cell.
Water temperature, dissolved oxygen, pH, conductivity, and turbidity were measured at one
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point in the grid, with a second measurement taken if an obvious water quality gradient existed
across the grid.
6.1.1.3.3. Data Analysis and HSC Curve Development
The first step in developing HSC curves for rearing juvenile salmon was to separate data by gear
type due to differences in effectiveness and because each gear was used selectively, dependent
upon sampling conditions. Different types of analyses were used for Chinook and coho salmon
in comparison to sockeye and chum salmon based on differences in territoriality and propensity
for schooling behavior. Suitability for Chinook and coho salmon was derived by dividing total
fish catch for a given habitat parameter value (utilization) by the number of cells fished with the
same habitat parameter value (effort). Fish density was assumed to be a function of mean catch
per cell. Differences in mean catch per cell by habitat value were analyzed with analysis of
variance and least squares regression.
For sockeye and chum salmon, suitability was derived by dividing the total number of cells with
fish present for a given habitat value (utilization) by the number of cells fished (effort). This
modification was needed for sockeye and chum salmon because the typical schooling behavior
exhibited by these species could lead to the capture of a large school within a cell, which might
disproportionately affect mean catch per cell. Differences in proportional presence by habitat
attribute value were analyzed with chi-square tests of association.
For all analyses, data from all sites over the entire season were pooled by species. Data from
tributary sites without major runs of sockeye salmon were excluded from the sockeye suitability
criteria development. Data collected between May 1 and 15, when only a small percentage of
sockeye had emerged, were also excluded. Because the vast majority of chum salmon
outmigrate from the upper Susitna River prior to July 15 (ADF&G 1983a), only data collected
before July 15 were used to develop suitability relationships for this species.
Statistical analyses used included analysis of variance, linear regression and chi-square tests of
association. All velocity and depth criteria were fit to the data by hand using professional
judgment to give the best fit.
6.1.1.4. Juvenile Salmon Rearing in the Lower Susitna River (Suchanek et al. 1985)
In 1984, Suchanek et al. (1985) conducted a follow-up study to evaluate juvenile salmon rearing
habitat suitability in the Lower Susitna River (below the Chulitna River confluence). The goal of
the study was to verify the applicability of the suitability criteria developed for the Middle
Segment of the Susitna River in 1983 by Suchanek et al. (1984b), such that the 1983 Middle
River curves could be used for the Lower River unless the 1984 studies in the Lower River
provided evidence for modifications.
6.1.1.4.1. Site Selection
Sampling sites included 20 habitat model sites that were normally sampled twice a month and 31
opportunistic sites which were usually sampled only once. The 20 modeled sites were
distributed between the Yentna River confluence and Talkeetna. Eight of these sites were
located within slough or side channel complexes. Four of the sites were normally clear-water
sloughs or tributary mouths while the other sites were turbid secondary side channels at normal
summer flows. Opportunistic sampling sites were selected by sampling crews as potential
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habitat which upon sampling might provide for a better analysis of fish abundance and
distribution. Sites sampled were more diverse than the modeled sites and included areas within
alluvial island complexes.
6.1.1.4.2. Collection Methods
Sampling methods were the same as those used during the 1983 studies in the Middle River
(Suchanek et al. 1984a) described above.
6.1.1.4.3. Data Analysis and HSC Curve Development
Initial data analysis methods were the same as those used by Suchanek et al. (1984a) in the
Middle River. However, additional methods were used to compare the Middle (1983) and Lower
(1984) River data. Comparisons were made by plotting the suitability criteria derived for the
Middle River on the same graph with corresponding data from the Lower River. After
normalizing criteria from the two years, composite weighting factors were calculated for each
cell using the 1983 suitability criteria and revised 1984 criteria. These weighting factors were
then compared with catch. If the fit of the 1984 data to the 1983 suitability criteria were
substantially different upon visual inspection, the 1983 criteria were modified.
6.1.1.5. Resident Fish (Suchanek et al. 1984b)
Studies related to the development of HSC for select resident fish species are described by
Suchanek et al. (1984b). The microhabitat suitability for rainbow trout, Arctic grayling, round
whitefish, and longnose suckers in the Middle Segment of the Susitna River were evaluated
using electrofishing, beach seine, and hook and line catch data and habitat data collected at radio
telemetry relocation sites (rainbow trout and burbot) and spawning sites (round whitefish).
6.1.1.5.1. Site Selection
Thirteen study sites were sampled from July to October, 1983 to develop HSC for adult resident
species. These sites were located between the Chulitna River confluence and Devils Canyon and
consisted of six tributary mouths, three tributaries, three side sloughs, and one upland slough.
Nine slough and tributary mouth sites with relatively high numbers of adult resident fish were
selected for sampling by boat electrofishing, which occurred twice a month from mid-July to
October. Supplemental observations of resident fish were also obtained during other study
efforts. The upper reaches of four tributaries were irregularly sampled by hook and line in
conjunction with other study efforts (Sundet and Wenger 1984). Juvenile and a few adult
resident fish were also captured incidentally at 35 sites sampled during the juvenile salmon
studies described above (Suchanek et al. 1984a). Microhabitat was also measured at relocation
sites of 24 radio tagged rainbow trout and burbot that included tributary mouths, sloughs, sites in
the mainstem Susitna River between RM 100.8 and RM 148.7 and at three tributaries.
6.1.1.5.2. Collection Methods
Adult and a small number of juvenile (< 200 mm) resident fish were captured at accessible
locations in the Middle Segment of the Susitna River using a boat mounted electrofishing unit.
In tributaries, adult resident fish were also captured by hook and line. Juvenile resident fish at
upland slough, side slough, mainstem and tributary sites were collected with beach seines and
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backpack electrofishing units. All resident fish were identified to species and length, sex, and
sexual maturity information were recorded. Juvenile resident fish were also captured
incidentally during juvenile anadromous sampling of cells and grids located at a greater diversity
of sites using beach seining and backpack electrofishing as described above.
Each microhabitat study location was divided into one to three grids, located such that water
quality conditions were as uniform as possible and to encompass a variety of habitat types. At
tributary mouths, one grid was established in the mainstem Susitna River upstream of the
tributary confluence, a second grid was established within or below the confluence where the
tributary was the primary water source, and a third grid was established where the mainstem and
tributary waters mixed. Slough and tributary sites each had one to three grids depending on the
water quality. Grid locations were reestablished during each sampling effort to account for
changes in hydraulic conditions. Each grid was subdivided into rectangular cells of varying
length and width. Stream width constituted the width of cells in tributaries, which were sampled
by hook and line. Cell widths at sloughs and tributary mouths, which were sampled by boat
electrofishing, were typically five feet which was the average effective capture width of the boat
electrofishing equipment used.
Microhabitat data was collected at relocation sites of four burbot and 20 rainbow trout that had
been radio tagged in 1983. These fish were tracked from airplanes and boats and habitat
measurements were taken after a radio tagged fish was relocated by boat to an area of no greater
than 30 feet by 30 feet; in some cases, radio tagged fish were observed. For each cell and radio
tagged fish relocation site, mean depth, mean velocity, turbidity, and other water quality
parameters were measured.
6.1.1.5.3. Data Analysis and HSC Curve Development
Due to differences in habitat conditions sampled, hook and line data were analyzed separately
from boat electrofishing data. Observations were grouped according to the frequency
distribution of each habitat parameter. Turbidity values were grouped into three categories (1-9
NTU, 10-30 NTU, and >30 NTU) based on inflection points at which light penetration changes
considerably in glacial systems in Alaska and because Chinook salmon fry were found to use
turbidities >30 NTU for cover.
After grouping, Kendall rank-order correlation coefficients were calculated between habitat
values and catch. Because cells varied in size, catch was standardized in terms of fish caught per
1,000 ft2 of surface area, which was assumed to reflect density as well as suitability. Suitability
was determined for velocity, depth, cover type, and percent cover. Velocity was considered an
important determinant of distribution and suitability criteria were fit by hand to the distributions
of catch using professional judgment for each species. Because data for velocities greater than
4.3 ft/s were not collected, it was assumed that suitability for all species was 0.0 for velocities
greater than 4.5 ft/s. Depth was not considered an important determinant of distribution;
therefore, suitability criteria were not fit to depth observations. However, because minimum
depth was considered limiting, suitability was conservatively set to 1.0 for all depths greater than
0.6 ft and to 0.0 for depths less than 0.5 ft.
While percent cover and cover type both were considered to have potential importance in
determining adult fish distribution, limited sample sizes only allowed for the consideration of
cover type. Turbidity was incorporated into suitability indices for cover type because the
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suitability of cells without cover was found to increase as turbidity increased. This was
accomplished by developing cover type suitability indices for both clear (<10 NTU) and turbid
(>30 NTU) conditions.
Overall, only round whitefish juveniles were captured in sufficient numbers at juvenile salmon
study sites to warrant development of HSC. The habitat parameters of velocity, depth, percent
cover and cover type were examined for criteria development.
6.1.2. Results
The following sections summarize the results of HSC data collection efforts and the resulting
development of HSC curves from the various 1980s studies. Results are organized and reported
by species and life stage and therefore include results from multiple studies.
6.1.2.1. Chum Salmon
Chum salmon HSC curves were developed for spawning in the Middle Segment of the Susitna
River (Vincent-Lang et al. 1984a) and for juvenile rearing in the Middle (Suchanek et al. 1984a)
and Lower segments (Suchanek et al. 1985). The basis for the curves developed for each life
stage is provided below.
6.1.2.1.1. Spawning
A total of 333 chum salmon redds were surveyed by Vincent-Lang et al. (1984a) during 1982
and 1983 for the habitat variables of depth, velocity, substrate, and the presence of upwelling
groundwater. Of these redds, 131 were within hydraulic simulation modeling study sites and had
associated availability data. Because of the limited number of measurements in Side Slough 8A
and Side Channel 21, only utilization (128 measurements) and availability data obtained in Side
Sloughs 9 and 21 were used in the evaluation of preference. This information was used to
develop chum salmon spawning HSC for depth, velocity, substrate, upwelling, and a combined
substrate/upwelling criteria index, which are described in the following sections.
Although depths less than 0.2 ft were available, they were not used by spawning chum salmon.
Depths less than 0.2 ft were therefore assigned a suitability index of 0.0 (Figure 6.1-1). A strong
preference was identified for depths between 0.8 and 2.3 ft (i.e., the frequency of utilization was
greater than the frequency of available), and therefore, these depths were assigned a suitability
index of 1.0. Based on published data (Hale 1981) and the opinion of project biologists familiar
with chum salmon in the Middle Segment of the Susitna River, it was assumed that depths >2.3
ft would not limit chum salmon spawning within the range of conditions encountered at the study
sites. Because the maximum predicted depth at all modeled study sites was 7.5 ft, the suitability
index of 1.0 was extended out to 8.0 ft. For depths from 0.8 to 2.3 ft, the ratio of utilized to
available habitat for the 0.2 to 0.5 ft increment was less than for the 0.5 to 0.8 ft increment.
Suitability was therefore assumed to increase in an exponential fashion over the range of 0.2 to
0.8 ft, which was reflected by assigning a suitability index of 0.2 to a depth of 0.5 ft.
A general preference was exhibited by spawning chum salmon for velocities between 0.0 and 1.3
ft/s. Thus, a suitability index of 1.0 was assigned to this range of velocities (Figure 6.1-2).
Suitability for higher velocities was subjectively determined because no concurrent
utilization/availability data were collected for velocities exceeding 1.3 ft/s. The maximum
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utilized velocity was 4.3 ft/s; thus, a velocity of 4.5 ft/s was selected as a maximum value and
assigned a suitability index of 0.0. Utilization from 1.3 ft/s to 2.8 ft/s was greater than from 2.8
ft/s to 4.5 ft/s. Therefore, a suitability index of 0.2 was assigned to a velocity of 2.8 ft/s.
Substrates ranging from large gravel to large cobble (reported simply as cobble) appear to be
preferred for chum spawning. However, published data (Hale 1981; Wilson et al. 1981) suggest
that large cobble substrates are less preferred for chum salmon spawning than large gravels and
small cobbles (reported as rubble). Discussions with field personnel also suggested a potential
sampling bias for larger substrates since field personnel were more likely to overestimate
substrate sizes. For these reasons, a suitability index of 1.0 was assigned to large gravel and
small cobble substrates (Figure 6.1-3). Larger cobble substrates were divided into several
increments and assigned suitability indices ranging from 0.85 to 0.25, while boulders were
assigned an index value of 0.0. Silt and smaller substrates were not utilized and were assigned a
suitability index of 0.0. A small utilized to available ratio was observed for sand increments,
which were assigned a low suitability index (0.025 and 0.05). This was supported by published
information (Hale 1981; Wilson et al. 1981). Intermediate substrate size classes were assigned
by assuming a linearly increasing suitability.
A binary approach was used to assign suitability criteria for upwelling. A suitability index of 1.0
was assigned for the presence of upwelling while a suitability index of 0.0 was assigned for the
absence of upwelling (Figure 6.1-4). This approach was considered justified based on field data
that indicated spawning chum salmon appear to key on upwelling (ADF&G 1983a). Suitability
criteria were also developed for the combination of substrate and upwelling. When upwelling is
present, criteria were identical to the individual substrate suitability criteria. However, when
upwelling is not present, a suitability index of 0.0 was assigned to each substrate class.
6.1.2.1.2. Juvenile Rearing
6.1.2.1.2.1. Middle Susitna River
Suchanek et al. (1984a) captured a total of 1,157 juvenile chum salmon from 514 sample cells
during efforts to collect juvenile salmon suitability criteria data in the Middle River (Table 6.1-
4). This total excludes some cells that were sampled after the period of peak chum salmon
outmigration to avoid biasing analyses based on the presence or absence of juvenile chum
salmon. Chi-square tests indicated that the association of juvenile chum salmon presence was
significant for depth, velocity, cover type, and percent cover.
To determine the relative importance of each habitat parameter, composite weighting factors
were developed using various combinations of habitat parameters. The effect of depth on the
distribution of juvenile salmon was not considered limiting beyond a minimum threshold, and
the inclusion of depth in composite weighting factors showed only minimal improvement in the
correlation with catch. Therefore, for juvenile chum and all other juvenile salmon species
considered, depths greater than or equal to 0.15 ft were assigned a suitability index of 1.0 (Figure
6.1-5). Depths less than 0.15 were assigned a suitability index of 0.0 based on professional
judgment.
Sample sizes were insufficient to develop separate suitability curves based on turbid vs. clear-
water conditions. Thus, observations from electrofishing (clear-water) and seining (turbid-water)
were pooled for analyses. Slow velocities between 0.0 and 0.35 ft/s were found to be optimal for
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juvenile chum salmon and were assigned a suitability index of 1.0 (Figure 6.1-6). Velocities
greater than 0.35 ft/s were assigned decreasing suitability indices, reaching 0.0 at velocities of
2.10 and greater.
Compared to juvenile sockeye, Chinook, and coho salmon, chum salmon rear for the shortest
duration in the Middle Susitna River (ADF&G 1983b). Suchanek et al. (1984a) observed that
juvenile chum initially use substrate as cover and then rely on protection provided by schooling
behavior. This was reflected by a greater relative use of large substrate for cover by chum
salmon compared to other species. Mean catches of juvenile chum salmon were less in cells
without object cover in turbid water, suggesting avoidance of turbid conditions. However, this
may have also been an artifact of clear-water conditions predominating near emergence areas.
Cover type and percent cover suitability are shown for juvenile chum salmon in Table 6.1-5.
6.1.2.1.2.2. Lower Susitna River
Sampling in 1984 by Suchanek et al. (1985) found that the use of side channels in the Lower
River of the Susitna River by juvenile chum salmon was limited by high turbidities. For this
reason, sampled cells with turbidities greater than 200 NTU were eliminated from suitability
criteria development. Cells were also excluded from analyses if they were sampled before the
date when most chum salmon outmigration occurred (July 16). After applying these criteria, 249
cells were available for analysis; juvenile chum were captured in 98 (39.4%) of these cells.
The distribution of chum presence by depth interval in the Lower River in 1984 was similar to
that found in the Middle River in 1983. Thus, the criteria developed for the Middle River was
generally the same as that developed for the Lower River (Figure 6.1-5). One exception was that
the curve developed for the Lower River increased directly from a suitability index of 0.0 (at a
depth of 0.0 ft) to 1.0 (at a depth of 0.1 ft). In contrast, the Middle Segment depth curve (used
for all juvenile salmon species) increased from a suitability index of 0.0 (at a depth of 0.14 ft) to
1.0 (at a depth of 0.15 ft). Presumably, this difference represents a lack of refinement to the
Lower River curve to account for a minimum depth requirement. Alternatively, 0.1-ft depth
increments may have been deemed adequate for modeling efforts, making the suitability of
depths between 0.0 and 0.1 irrelevant.
With respect to velocity, data collected in the Lower River in 1984 indicated that the distribution
of juvenile chum presence was similar to the Middle Segment in 1983. Therefore, the suitability
criteria for chum salmon developed for the Middle Segment in 1983 was selected for use in 1984
for the Lower River (Figure 6.1-6).
The relationship of chum salmon use to percent cover and cover type in the Middle Segment in
1983 was the weakest of any of the four species. In the Lower River in 1984, the 0-5% cover
category and the "no cover" type had the highest proportional presence within their respective
distributions, suggesting that chum salmon fry do not orient to cover during rearing. Because no
trends were apparent, cover type and percent cover were not used in the 1984 analysis of chum
habitat use. Thus, a suitability index of 1.0 was applied to all cover types and percentages of
cover for the Lower River (Table 6.1-6). Again, the lack of a relationship between juvenile
chum and cover was attributed to a reliance on schooling behavior for protection from predators
rather than cover.
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6.1.2.2. Sockeye Salmon
Sockeye salmon HSC curves were developed for spawning in the Middle Segment (Vincent-
Lang et al. 1984a) and for juvenile rearing in the Middle (Suchanek et al. 1984a) and Lower
segments (Suchanek et al. 1985). The basis for the curves developed for each life stage are
provided below.
6.1.2.2.1. Spawning
During 1982 and 1983, a total of 81 sockeye salmon redds were sampled by Vincent-Lang et al.
(1984a) for depth, velocity, substrate, and the presence of upwelling groundwater. Of these
redds, only one was located within a hydraulic simulation modeling study site, which precluded
an analysis of preference for sockeye salmon spawning. Thus, the derived sockeye salmon
spawning HSC were based solely on utilization data, as modified by the professional opinion of
project biologists familiar with middle Susitna River sockeye salmon stocks using literature data
and accumulated field observations. This information resulted in HSC for depth, velocity,
substrate, upwelling, and a combined substrate/upwelling criteria index, which are described in
the following sections.
Depths from 0.0 to 0.2 ft were not utilized for spawning and were therefore assigned a suitability
index of 0.0 (Figure 6.1-7). Depths that were most utilized centered around 0.75 ft, which was
therefore assigned a suitability index of 1.0. It was assumed that depths greater than 0.75 ft
would not likely limit sockeye salmon spawning within the range of conditions in the study sites,
based on the opinion of project biologists. The suitability index of 1.0 was therefore extended
out to 8.0 ft. Depths ranging from 0.2 to 0.5 ft were thought to be less suitable for spawning than
depths ranging from 0.5 to 0.75 ft. Thus, a suitability index of 0.9 was assigned to a depth of 0.5
ft.
For a velocity of 0.0 ft/s, a suitability index of 1.0 was assigned (Figure 6.1-8); this suitability
index was extended out to a velocity of 1.0 ft/s based on a review of literature data (USFWS
1983) and the opinion of project biologists. A suitability index of 0.0 was assigned to a velocity
of 4.5 ft/s to be consistent with the endpoint of the velocity curve for chum salmon spawning.
This rationale was applied because it was assumed that velocities for sockeye salmon spawning
would be no greater than for chum salmon spawning and because data were not available to
support lower velocities as an end point. Velocities ranging from 1.0 to 3.0 ft/s were thought to
be more suitable for sockeye salmon spawning than velocities from 3.0 to 4.5 ft/s. Therefore, a
suitability index of 0.10 was assigned to a velocity of 3.0 ft/s.
Large gravel and small cobble substrates appeared to be most often utilized for sockeye salmon
spawning. This finding was supported by published information (USFWS 1983), and these
substrates were assigned a suitability index of 1.0 (Figure 6.1-9). Large cobble and boulder
substrates were also utilized for spawning but to a lesser extent. However, the apparent
utilization of these 1arger substrates was thought to reflect a sampling bias toward larger
substrates than smaller substrates; that is, field personnel more likely noted larger substrate sizes
than smaller substrate sizes. Published information (USFWS 1983) also showed that large
cobble and boulder substrates were not as preferred as large gravels and small cobble.
Therefore, substrates between small cobble and large cobble were assigned a suitability index
from 0.90 to 0.10, respectively. Boulders were assigned a suitability index of 0.0 as were
substrates of sand and silt. Moderate utilization of small gravel substrates were observed though
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accumulated field experience and literature information (USFWS 1983) suggested that larger
gravel substrates would be more suitable for sockeye spawning. Thus, suitability index of 0.10
were assigned to substrates between sand and small gravel, 0.50 to small gravel substrate, 0.95 to
substrates between small gravel and large gravel.
Suitability criteria for upwelling were assigned using a binary approach in which a suitability
index of 1.0 was assigned where upwelling was present and a suitability index of 0.0 was
assigned where upwelling was absent (Figure 6.1-10). This approach was considered justified
based on field data that indicated spawning sockeye salmon appear to key on upwelling
(ADF&G 1983a). Suitability criteria were also developed for the combination of substrate and
upwelling. When upwelling is present, criteria were identical to the individual substrate
suitability criteria. However, when upwelling is not present, a suitability index of 0.0 was
assigned to each substrate class.
6.1.2.2.2. Juvenile Rearing
6.1.2.2.2.1. Middle Susitna River
Suchanek et al. (1984a) captured a total of 1,006 juvenile sockeye salmon from 1,013 sample
cells during efforts to collect juvenile salmon suitability criteria data in the Middle Susitna River
(Table 6.1-4). To avoid biasing analyses based on the presence or absence of juvenile sockeye
salmon, this total excludes some cells that were sampled in tributaries without major sockeye
salmon runs or when only a small percentage of sockeye had emerged. Chi-square tests
indicated that the association of juvenile sockeye salmon presence was significant for depth,
velocity, cover type, and percent cover.
To determine the relative importance of each habitat parameter, composite weighting factors
were developed using various combinations of habitat parameters. The effect of depth on the
distribution of juvenile salmon was not considered limiting beyond a minimum threshold, and
the inclusion of depth in composite weighting factors showed only minimal improvement in the
correlation with catch. Therefore, for juvenile sockeye and all other juvenile salmon species
considered, depths greater than or equal to 0.15 ft were assigned a suitability index of 1.0 (Figure
6.1-11). Depths less than 0.15 were assigned a suitability index of 0.0 based on professional
judgment.
Sample sizes were insufficient to develop separate suitability curves based on turbid vs. clear-
water conditions. Thus, observations from electrofishing (clear-water) and seining (turbid-water)
were pooled for analyses. Slow velocities between 0.0 and 0.05 ft/s were found to be optimal for
juvenile sockeye salmon and were assigned a suitability index of 1.0 (Figure 6.1-12). Velocities
greater than 0.05 ft/s were assigned decreasing suitability indices, reaching 0.0 at velocities of
2.10 and greater.
Compared to Chinook and coho juveniles, sockeye juveniles were apparently much less
dependent on cover because they are more likely to use the schooling behavior as a means of
predator avoidance. Schools of sockeye juveniles were observed ranging throughout areas
varying from heavy cover to no cover. However, the distribution of juvenile sockeye salmon
appeared to have some relationship to cover, reflected in the suitability indices developed. Cover
type and percent cover suitability are shown for juvenile sockeye salmon in Table 6.1-5.
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6.1.2.2.2.2. Lower Susitna River
Sampling in 1984 by Suchanek et al. (1985) found that the use of Lower River side channels by
juvenile sockeye salmon was limited by high turbidities. For this reason, sampled cells with
turbidities greater than 250 NTU were eliminated from suitability criteria development. After
these cells were excluded, 922 cells were available for analysis; juvenile sockeye were captured
in 117 (12.7%) of these cells.
No trend was noted in the 1984 depth distribution data for the Middle River. Fish were captured
in 2 of the 20 cells sampled with a depth of 0.1 ft, suggesting that this depth was suitable. The
distribution of chum presence by depth interval in the Lower River in 1984 was similar to that
found in the Middle Segment in 1983. Thus, the criteria developed for the Middle River was
generally the same as that developed for the Lower River (Figure 6.1-11). One exception was
that the curve developed for the Lower River increased directly from a suitability index of 0.0 (at
a depth of 0.0 ft) to 1.0 (at a depth of 0.1 ft). In contrast, the Middle River depth curve (used for
all juvenile salmon species) increased from a suitability index of 0.0 (at a depth of 0.14 ft) to 1.0
(at a depth of 0.15 ft). Presumably, this difference represents a lack of refinement to Lower
River curve to account for a minimum depth requirement. Alternatively, 0.1-ft depth increments
may have been deemed adequate for modeling efforts, making the suitability of depths between
0.0 and 0.1 irrelevant.
With respect to velocity, the proportional presence of juvenile sockeye in the Lower River in
1984 by velocity interval was very similar to that found in the Middle Segment in 1983.
Velocities greater than 1.2 ft/s were not used by juvenile sockeye in either year, although Middle
River sample sizes were smaller. Because no use was observed at velocities greater than 1.2 ft/s,
the curve developed in 1984 for the Lower River was revised such that velocities greater than 1.2
ft/s had a suitability index of 0.0 (Figure 6.1-12).
For percent cover, the distribution of proportional presence was similar to that found in the
Middle River of the Susitna River in 1983. The 1983 suitability relationship was therefore
selected in 1984 for use in the Lower River (Table 6.1-6). For cover type, the distribution of
proportional presence by cover type categories differed slightly from that found in the Middle
Segment in 1983. Thus, the cover type suitabilities developed for the Middle Segment were
deemed appropriate for the Lower River, with two exceptions. Because sample sizes were small
(less than 25) for the cover type categories of undercut bank and overhanging riparian
vegetation, suitabilities calculated for the Middle Segment were averaged with the Lower River
suitabilities to give a value intermediate between the two (Table 6.1-6).
6.1.2.3. Chinook Salmon
Chinook salmon HSC curves were developed for spawning in the Middle River (Vincent-Lang et
al. 1984b) and for juvenile rearing in the Middle (Suchanek et al. 1984a) and Lower segments
(Suchanek et al. 1985). The basis for the curves developed for each life stage are provided
below.
6.1.2.3.1. Spawning
A total of 265 Chinook salmon redds were sampled during 1983 for the habitat variables of
depth, velocity, and substrate. Of these redds, the majority of measurements were made in
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Portage Creek (n=137) and Indian River (n=125). This information was used to develop HSC
for Chinook spawning depth, velocity, and substrate, which are described in the following
sections.
Chinook salmon did not utilize depths from 0.0-0.5 ft for spawning; this range of depths was
therefore assigned a suitability index of 0.0 (Figure 6.1-13). Depths ranging from 1.0 to 1.6 ft
appeared to be most often utilized for spawning and were therefore assigned a suitability index
of 1.0. Based on utilization patterns, a linear relationship between depth and suitability was
assumed for depths between 0.5 and 1.0 ft. Because it was assumed that depths greater than 1.6 ft
would not likely limit spawning, a suitability index of 1.0 was extended out to depths of 4.0 ft,
which was the maximum depth commonly encountered in tributary habitats of the middle
Susitna River.
Velocities ranging from 0.0-0.3 ft/s were not utilized for spawning and thus were assigned
suitability indices of 0.0 (Figure 6.1-14). Velocities from 1.7 to 2.3 ft/s were most often utilized
for spawning and were therefore assigned a suitability index of 1.0. Suitability indices of 0.25
and 0.60 were assigned to velocities of 0.8 and 2.6 ft/s, respectively, based on observed
utilization. Velocities greater than 4.5 ft/s were considered unsuitable for spawning and assigned
a suitability index of 0.0.
Utilization data indicated that small cobble substrates were the most often utilized for spawning.
These size classes were assigned a suitability index of 1.0 (Figure 6.1-15). Based on literature
information (Beauchamp et al. 1983; Estes et al. 1981), the suitability index of 1.0 extended to
include large gravel substrates. Small gravel and smaller substrates were not utilized; however,
1iterature data (Beauchamp et al. 1983; Estes et al. 1981) indicated that small to large gravel
substrates may be used by spawning Chinook salmon. A linear relationship between substrate
and suitability was therefore assumed for substrates ranging from small gravel (with a suitability
of 0.0) to large gravel/small cobble (with a suitability of 1.0). Large cobble and boulder
substrates were a1so utilized, but to a lesser extent than small cobble substrates. However, it was
assumed that the field observations were biased toward larger substrates and 1iterature
information indicated that large cobble and boulder substrates were less preferred than large
gravel and small cobble substrates (Beauchamp et al. 1983; Estes et al. 1981). Based on this
rationale, large cobble substrates were assigned a suitability index of 0.7, large cobble/boulder
substrates were assigned a suitability index of 0.35, and boulder substrates were assigned a
suitability index of 0.0.
6.1.2.3.2. Juvenile Rearing
6.1.2.3.2.1. Middle Susitna River
Suchanek et al. (1984a) captured a total of 4,395 juvenile Chinook salmon from 1,260 sample
cells during efforts to collect juvenile salmon suitability criteria data in the Middle Susitna River
(Table 6.1-4). Chinook salmon were the only juvenile salmon captured in sufficient numbers to
develop separate suitability curves based on turbid vs. clear-water conditions. Thus,
observations from electrofishing (clear-water) and seining (turbid-water) were analyzed
separately. Analysis of variance on clear-water data indicated that depth and velocity were not
significantly related to juvenile Chinook catch when considered individually, but were
significant when considered together. Both cover type and percent cover were significantly
related to juvenile Chinook catch. Analysis of variance on turbid-water data indicated that
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juvenile Chinook catch was significantly related to velocity but not depth. The effect of object
cover was not analyzed for significance because seining effectiveness was reduced by the
amount and type of object cover. Moreover, object cover was considered less important when
turbidity was available.
To determine the relative importance of each habitat parameter, composite weighting factors
were developed using various combinations of habitat parameters. The effect of depth on the
distribution of juvenile salmon was not considered limiting beyond a minimum threshold, and
the inclusion of depth in composite weighting factors showed only minimal improvement in the
correlation with catch. Therefore, for juvenile Chinook and all other juvenile salmon species
considered, depths greater than or equal to 0.15 ft were assigned a suitability index of 1.0
(Figure 6.1-16). Depths less than 0.15 were assigned a suitability index of 0.0 based on
professional judgment. While separate depth curves were not developed for clear- vs. turbid-
water conditions, Suchanek et al. (1984a) suggested that juvenile Chinook preferred shallower
depths in turbid water.
Under clear-water conditions, velocities between 0.35 and 0.65 ft/s were found to be optimal for
juvenile Chinook salmon and were assigned a suitability index of 1.0 (Figure 6.1-17). Velocities
greater than 0.65 ft/s were assigned decreasing suitability indices, reaching 0.0 at velocities of
2.60 and greater. Under turbid-water conditions, juvenile Chinook appeared to prefer slower
velocities; velocities between 0.05 and 0.35 ft/s were found to be optimal and were assigned a
suitability index of 1.0 (Figure 6.1-17). Velocities greater than 0.35 ft/s were assigned
decreasing suitability indices, and like the clear-water curve, reached 0.0 at velocities of 2.60 and
greater. Suchanek et al. (1984a) suggested that the preference for slower velocities in turbid
water may be attributable to the absence of velocity breaks to rest behind when turbidity is used
for cover rather than objects.
The use of object cover appeared stronger in clear-water compared to turbid water. While the
limited use of object cover apparent in turbid water was partly due to gear bias from seining,
Suchanek et al. (1984a) found that the distribution of juvenile Chinook salmon was clearly
different in turbid water compared to clear water. Depth and velocity were considered the
greatest influence on distribution in turbid water, while object cover was more important in clear
water. It was concluded that turbidity was used as cover rather than object cover. Thus,
suitability criteria for various cover types and percent-cover were developed for clear-water
conditions, whereas turbid-water suitability criteria was only varied based on percent cover; all
turbid-water cover types were assigned the same suitability (Table 6.1-5).
6.1.2.3.2.2. Lower Susitna River
Data collected in the Lower River by Suchanek et al. (1985) in 1984 showed that high turbidity
may limit the distribution of Chinook salmon. Thus, sampled cells were excluded from analyses
if turbidities were greater than 350 NTU. Of the remaining 1,155 sample cells, 400 were
sampled in water with a turbidity of 30 NTU or less; as with sampling in the Middle River in
1983, 30 NTU was used as the breakpoint between turbid and clear water. Mean adjusted catch
was 1.3 fish per cell in the 400 clear-water cells, and 1.1 fish per cell in the 755 turbid cells.
Comparisons between Middle and Lower river data were made independently for clear-water and
turbid-water conditions.
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While Middle River efforts in 1983 suggested that depth in clear water had little effect on
juvenile Chinook catch relative to other habitat parameters, Lower River efforts in 1984
suggested a more frequent use of greater depths. Based on this finding, a clear-water Lower
River depth curve was developed using professional judgment in which only depths greater than
2.1 ft were assigned a suitability index of 1.0 (Figure 6.1-16). For turbid-water conditions, the
Lower River depth curve was developed by adjusting the Middle River curve such that optimum
depths ranged from 0.3 to 1.5 ft (Figure 6.1-16). A depth of 0.1 ft was also modified to have a
suitability >0.0 based on observations of limited Chinook use at this depth.
In clear water, the distribution of Chinook catch in the Middle River in 1984 showed peak
catches at velocities ranging from 0.1 to 0.3 fps. This range suggested that under clear-water
conditions, Chinook used lower velocities in the Lower River compared to the Middle River.
The 1984 clear-water distribution of catch by velocity interval was more similar to the 1983
turbid-water suitability criteria. Thus, the 1983 turbid-water velocity criteria from the Middle
River were selected to represent the clear-water velocity criteria for the Lower River (Figure 6.1-
17). Under turbid-water conditions, velocities used by juvenile Chinook were similar in the
Lower and Middle River and the turbid-water Middle River velocity criteria was considered
appropriate for the Lower River. Thus, the selected velocity criteria for the Lower River was
identical for turbid- and clear-water conditions (Figure 6.1-17).
In clear water, the observed relationship between percent cover and catch in the Lower River was
found to be very similar to the suitability criteria developed for the Middle River in 1983. Thus,
the Middle River suitability criteria were considered a good estimate of this relationship for the
Lower River (Table 6.1-6). Likewise, the turbid-water Middle River suitability criteria for
percent cover were deemed appropriate for turbid-water conditions in the Lower River.
Clear-water cover type suitabilities derived for the Lower River in 1984 differed dramatically
from those derived in the Middle River in 1983. Compared to the Middle River, debris was used
less frequently in the Lower River while emergent vegetation was more frequently used. Thus,
the clear-water cover type suitability criteria for the Lowe River was adjusted accordingly (Table
6.1-6). Catches in cells without object cover were also relatively higher in the Lower River than
in the Middle River. However, this difference was attributed to a greater use of deeper water for
cover in the Lower River, and suitability for “no cover” from the Middle River was therefore
retained. While turbid-water cover type suitability criteria were not developed for the Middle
River, Suchanek et al. (1985) refined cover type suitability criteria specific to the Lower River.
To account for the reduced importance of object cover under turbid conditions, a maximum
suitability index of 0.4 was applied to all cover types.
6.1.2.4. Coho Salmon
Coho salmon HSC curves were developed for spawning for the Middle River (Vincent-Lang et
al. 1984b) and for juvenile rearing in the Middle (Suchanek et al. 1984a) and Lower River
(Suchanek et al. 1985). The bases for the curves developed for each life stage are provided
below.
6.1.2.4.1. Spawning
Utilization data were not collected for coho salmon spawning in the Susitna River during the
1980s. However, Vincent-Lang et al. (1984b) developed HSC for the habitat variables of depth,
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velocity, and substrate based entirely on previously published information, as modified using the
opinion of field biologists familiar with Susitna River salmon stocks. Due to limited published
information available on coho salmon spawning habitat requirements in the Susitna River
watershed, the coho salmon spawning HSC developed for the Terror Lake environmental
assessment (Wilson et a1. 1981) were chosen as the basis for modification.
The depth HSC developed for coho salmon spawning generally followed the Terror lake system
curve, with the exception that the curve developed for the Susitna River deflected upward at a
depth of 0.3 ft as opposed to 0.5 ft in the Terror Lake curve (Figure 6.1-18). This was based on
the opinion of project biologists that depths less than 0.5 ft but greater than 0.3 ft, would be
suitable for coho spawning. Additionally, the suitability index of 1.0 was extended out to a
depth of 4.0 ft based on the opinion of project biologists that depth alone, if greater than 2.0 ft
(the depth at which suitability on the Terror Lake curve begins to decline) would not likely limit
coho salmon spawning.
The velocity HSC developed for coho salmon spawning generally coincided with the velocity
curve developed for the Terror Lake system. The curve was smoothed slightly to reflect the
opinion of field biologists familiar with coho salmon spawning in the Susitna River watershed
(Figure 6.1-19).
The substrate suitability criteria curve developed for coho salmon spawning in the Terror Lake
system was thought to be representative of substrate suitability for coho salmon spawning in the
middle reach of the Susitna River and is reflected in the criteria presented (Figure 6.1-20).
6.1.2.4.2. Juvenile Rearing
6.1.2.4.2.1. Middle Susitna River
Suchanek et al. (1984a) captured a total of 2,020 juvenile coho salmon from 1,260 sample cells
during efforts to collect juvenile salmon suitability criteria data in the Middle Susitna River
(Table 6.1-4). Sample sizes were insufficient to develop separate suitability curves based on
turbid vs. clear-water conditions. Juvenile coho catches were small in turbid water and
electrofishing (clear-water) data were deemed sufficient for criteria development. Thus, juvenile
coho criteria were developed based exclusively on catches under clear-water conditions.
Analysis of variance indicated that depth and velocity were significantly related to juvenile coho
catch, as were both cover type and percent cover. To determine the relative importance of each
habitat parameter, composite weighting factors were developed using various combinations of
habitat parameters. The effect of depth on the distribution of juvenile salmon was not considered
limiting beyond a minimum threshold, and the inclusion of depth in composite weighting factors
showed only minimal improvement in the correlation with catch. Therefore, for juvenile coho
and all other juvenile salmon species considered, depths greater than or equal to 0.15 ft were
assigned a suitability index of 1.0 (Figure 6.1-21). Depths less than 0.15 were assigned a
suitability index of 0.0 based on professional judgment.
Velocities between 0.05 and 0.35 ft/s were considered optimal for juvenile coho salmon and
were assigned a suitability index of 1.0 (Figure 6.1-22). Velocities greater than 0.35 ft/s were
assigned decreasing suitability indices, reaching 0.0 at velocities of 2.10 and greater.
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Suchanek et al. (1984a) suggested that the distribution of juvenile coho salmon fry may be
1imited by a lack of suitable cover type, noting very strong preferences for certain cover types
such as debris and undercut banks. Unlike juvenile Chinook salmon, substrate was seldom used
as cover by juvenile coho. Also unlike Chinook salmon, coho salmon did not appear to use
turbid water as cover. This was consistent with other studies reviewed by Suchanek et al.
(1984a), including Bisson and Bilby (1982) and Sigler et al. (1984). In addition, catches of coho
salmon were very low in turbid side channels (Dugan et al. 1984). However, cover types
preferred by coho were also very scarce at these sites and almost impossible to sample
effectively with seines. Suchanek et al. (1984a) speculated that coho may leave a site when
turbidities exceed a certain level. Based on this information, suitability criteria developed for
percent cover and cover type are provided in Table 6.1-5.
6.1.2.4.2.2. Lower Susitna River
Sampling in 1984 by Suchanek et al. (1985) captured few coho in habitat types other than
tributary mouths in the Lower River. Therefore, only tributary mouth data were used to compare
suitability criteria for the Middle and Lower River. Turbidities in the tributary mouths were
generally less than 30 NTU.
A total of 345 cells with complete habitat data were sampled in tributary mouths as well as
another 2 cells with partial habitat data. The mean adjusted catch in these cells was 1.2 fish/cell.
Of the habitat parameters considered, cover type was most highly correlated with coho catch.
For depth, the catch distributions from the Lower River in 1984 were very different from catch
distributions in the Middle River in 1983. However, after adjusting for the effects of velocit y,
percent cover, and cover type there was no trend in depth suitability. Therefore, depth suitability
criteria for the Lower River was not changed from that developed for the Middle River (Figure
6.1-21).
For velocity, the catch distribution from the Lower River in 1984 matched closely with the
suitability criteria derived for the Middle River in 1983. The Middle River velocity criteria were
therefore chosen as representative for the Lower River (Figure 6.1-22).
In relation to percent cover, the distribution of coho catch data from the Lower River in 1984
showed slight differences from the Middle River data in 1983. However, after adjusting for the
effects of other habitat parameters, results from the two years appeared more similar. Because
the 1983 sample size was larger, the percent cover suitability relationship for the Middle River
was chosen for use in the Lower River (Table 6.1-6).
Initial calculations of the suitability of cover type indicated that suitabilities in the Lower River
in 1984 were similar to those found in the Middle River. However, after adjusting for the effects
of other habitat parameters, some differences were apparent and the cover type suitability for the
Lower River was adjusted accordingly (Table 6.1-6).
6.1.2.5. Pink Salmon Spawning
Utilization data were not collected for pink salmon spawning in tributaries of the Middle River
during the 1980s. Rather, Vincent-Lang et al. (1984b) developed depth, velocity, and substrate
HSC for pink salmon spawning based solely on previously published information as modified by
the opinions of project biologists familiar with Susitna River pink salmon stocks. As with coho
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salmon, limited information was available on pink salmon spawning habitat suitability in the
Susitna River watershed (Estes et al. 1981). Therefore, spawning HSC developed in the Terror
Lake environmental assessment (Wilson et al. 1981) were chosen as the basis for modification.
Because the Terror River has hydraulic and physical characteristics similar to many of the larger
clear water tributaries of the middle Susitna River, the curves developed for pink salmon depth,
velocity, and substrate spawning suitability were considered an appropriate basis for
modification by Vincent-Lang et al. (1984b). The depth suitability criteria curve developed for
pink salmon spawning approximated the depth suitability curve developed for the Terror Lake
system, except that the suitability index of 0.0 was extended from 0.1 to 0.3 ft (Figure 6.1-23). It
was also assumed that depths less than 0.3 ft would not be suitable for pink salmon spawning. A
final modification was to extend the suitability index of 1.0 out to 4.0 feet based on the opinion
of field biologists that depths greater than 2.5 ft (the depth at which suitability in the Terror Lake
curves begins to decline) would not likely limit pink salmon spawning in tributaries of the
Middle Susitna River.
The velocity suitability criteria curve developed for pink salmon spawning generally matched the
velocity suitability curve developed for the Terror Lake system except that velocities ranging
from 2.0 to 5.0 ft/s were assigned slightly higher suitability indices (Figure 6.1-24). This
modification was based on the opinions of project biologists that these velocities are utilized to a
greater degree by spawning pink salmon in tributaries of the Middle River.
The substrate suitability criteria curve developed for pink salmon spawning in the Terror Lake
system was considered representative of substrate suitability for pink salmon spawning in the
Middle Susitna River (Figure 6.1-25).
6.1.2.6. Rainbow Trout Adult
Suchanek et al. (1984b) captured a total of 143 adult rainbow trout by boat electrofishing (n=44)
and hook-and-line sampling (n=99) in the Middle Susitna River (Table 6.1-7). Adult rainbow
trout captured by boat electrofishing were typically found in cells with water velocities less than
1.5 ft/s. Preferred cover types included rocks with diameters >3 inches, and secondarily, debris
and overhanging riparian vegetation. The highest densities of adult rainbow trout were found in
cells with 6 to 25% object cover and greater than 50% object cover.
Results of hook and line sampling suggested that adult rainbow trout preferred pools with depths
greater than 2.0 ft. As with other adult resident species however, depth was only thought to limit
the distribution of adult rainbow trout as a minimum. Therefore, for all adult resident species,
depth suitability was conservatively set to 1.0 for all depths greater than 0.6 ft, and to 0.0 for
depths less than 0.5 ft (Figure 6.1-26).
Results of hook and line sampling suggested that adult rainbow trout preferred pools with
velocities less than 0.5 ft/s. However, because electrofishing data were collected at more cells in
a wider variety of habitat types, velocity HSC were fit to the boat electrofishing data. Based on
this information, velocities between 0.05 and 1.05 ft/s were assigned a suitability of 1.0, with
decreasing suitability values up to 4.5 ft/s, which was assigned a suitability of 0.0 (Figure 6.1-
27).
Hook and line sampling also suggested that adult rainbow trout used debris, undercut bank, and
riparian vegetation cover more than cobble or boulder cover. Abundant cover was generally
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considered important to adult rainbow trout distribution. Because electrofishing data were
collected at more cells in a wider variety of habitat types, cover type HSC were also fit to the
boat electrofishing data. Since the hook and line data suggested that debris, overhanging riparian
vegetation, and undercut bank cover types were more suitable than cobble or boulders, suitability
for these cover types were adjusted to the suitability of cobble and boulders, which was 1.0.
Suitability indices for each cover type are presented in Table 6.1-8 and were developed for both
clear- and turbid-water conditions.
6.1.2.7. Arctic Grayling
Suchanek et al. (1984b) captured a total of 140 adult arctic grayling by boat electrofishing
(n=138) and hook-and-line sampling (n=2) in the Middle Susitna River (Table 6.1-7). Adult
arctic grayling were often found to use rocks for cover as well as high velocity and relatively
deep water (Suchanek et al. 1984b). As with other adult resident species, however, depth was
only thought to limit the distribution of adult arctic grayling as a minimum. Therefore, for all
adult resident species, depth suitability was conservatively set to 1.0 for all depths greater than
0.6 ft, and to 0.0 for depths less than 0.5 ft (Figure 6.1-28). HSC were developed by fitting catch
distributions to values of observed velocity (Figure 6.1-29) and cover type. Arctic grayling were
thought to avoid high turbidity waters and make little use of turbidity for cover. Suitability
indices for each cover type are presented in Table 6.1-8 and were developed for both clear- and
turbid-water conditions.
6.1.2.8. Round Whitefish
Round whitefish HSC curves were developed for adults and juvenile rearing in the Middle River
(Suchanek et al. 1984b). The basis for the curves developed for each life stage is provided
below.
6.1.2.8.1. Adult
Suchanek et al. (1984b) captured a total of 138 adult round whitefish by boat electrofishing in
the Middle Susitna River (Table 6.1-7). As with other adult resident species considered, depth
was only thought to limit the distribution of adult round whitefish as a minimum. Therefore, for
all adult resident species, depth suitability was conservatively set to 1.0 for all depths greater
than 0.6 ft, and to 0.0 for depths less than 0.5 ft (Figure 6.1-30).
HSC for velocity (Figure 6.1-31) and cover type were developed by fitting suitability values to
catch distributions. Velocity did not appear to have a strong effect on distribution, although
observations most frequently occurred at velocities of 2 to 3 ft/s. Distribution of adult round
whitefish was influenced by turbidity, presumably as a use of cover. Round whitefish also used
object cover, most frequently in the form of cobble or boulders, debris, and overhanging riparian
vegetation. Suitability indices for each cover type are presented in Table 6.1-8 and were
developed for both clear- and turbid-water conditions.
6.1.2.8.2. Juvenile Rearing
Suchanek et al. (1984b) found that turbidity had a significant (p< 0.01) effect on the relative
abundance of juvenile round whitefish. Catch rates in water with turbidity less than 30 NTU
were extremely low. The total catch (n=569) of round whitefish by beach seines in turbid
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(greater than 30 NTU) water was predominantly comprised of age 0+ juveniles. Mean catches
by velocity, depth and percent cover suggested that velocity had the greatest effect on
distribution. Juvenile round whitefish showed a strong preference for water without a significant
velocity. Catches in cells with little object cover were higher than in cells with large amounts of
cover, suggesting that object cover is not major determinant of habitat use. However, because
beach seining efficiency was greatly reduced by the amount and type of cover present, catch
distributions by cover type were not presented. For round whitefish fry, shallow depths were
found to be most suitable.
Round whitefish were the only juvenile resident species for which Suchanek et al. (1984b)
captured sufficient numbers to develop HSC. HSC were fit to the catch distributions for both
depth (Figure 6.1-32) and velocity (Figure 6.1-33) by hand using professional judgment.
Suitability for turbid water for all cover types was set to 1.0 and suitability for all cover types in
clear water was set to 0.0 (Table 6.1-8).
6.1.2.9. Longnose Sucker Adult
Suchanek et al. (1984b) captured a total of 157 adult longnose sucker by boat electrofishing in
the Middle Susitna River (Table 6.1-7). As with other adult resident species, depth was only
thought to limit the distribution of adult longnose sucker as a minimum. Therefore, for all adult
resident species, depth suitability was conservatively set to 1.0 for all depths greater than 0.6 ft,
and to 0.0 for depths less than 0.5 ft (Figure 6.1-34). Adult longnose sucker HSC were
developed for velocity (Figure 6.1-35) and cover type by fitting observed distributions of catch.
Adult longnose suckers were often found to use turbid water for cover, but also emergent or
aquatic vegetation, debris, and overhanging riparian vegetation (Suchanek et al. 1984b). Shallow
depths and waters of low velocity were found to be most suitable. Suitability indices for each
cover type are presented in Table 6.1-8 and were developed for both clear- and turbid-water
conditions.
6.1.2.10. Burbot Adult
Suchanek et al. (1984b) captured a total of 18 adult burbot by boat electrofishing in the Middle
Susitna River (Table 6.1-7). Other catch data from the 1980s consistently documented adult
burbot in the mainstem during the summer (ADF&G 1983c), suggesting they prefer areas of
moderate to high turbidities (Suchanek et al. 1984b). Telemetry data also found burbot
consistently in the mainstem. While in these mainstem areas, radio tagged burbot appeared to
prefer low velocities (<1.5 ft/s) and shallow depths (approximately 2.5 ft). Burbot also appeared
to prefer areas with small cobble (referred to as rubble) or large cobble (referred to as simply
cobble) substrate; however, nearly all of the mainstem river between the Chulitna River
confluence and Devils Canyon, where the radio tagged fish were found, had predominately small
or large cobble substrate. Burbot catches were insufficient to develop HSC for this species.
6.2. Other Relevant HSC Curve Sets
While the HSC curves developed for the Susitna River during the 1980s represent the most site-
specific information available for the Susitna-Watana IFS, reviewing other curve sets offers a
comparative means for evaluating similarities and differences for a given species and life stage.
Vincent-Lang et al. (1984a, 1984b) and Suchanek et al. (1984a) reviewed other curve sets
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available at the time and some of the resulting comparisons are described below. Additional
HSC data were compiled, reviewed and compared with the 1980s data as part of this evaluation.
Given the scope of curve sets already developed for the Susitna River, the comparisons were
limited to information from Alaska studies.
6.2.1. Study Descriptions
Baldrige (1981) developed HSC curve sets for the Terror and Kizhuyak rivers, located on the
northern end of Kodiak Island, Alaska. These curves were also reviewed by researchers for the
Su-Hydro instream flow study of the 1980s, using an alternate reference citation (Wilson et al.
1981). Fish species present in the Terror and Kizhuyak basins include pink, chum, and coho
salmon, and Dolly Varden. The Terror River basin drains a 46.3-square mile area and average
annual flow is 224 cfs. The river valley is broad, U-shaped, and supports abundant vegetation.
The Kizhuyak River basin drains approximately 54 square miles and monthly flows average
between 24 and 370 cfs. Study reaches were located in the lower and middle reaches of the
Kizhuyak River. Channel form consists of a broad, flat floodplain, leading into an intertidal
delta system. Preliminary curves were formed from available literature for the Kodiak Island
area. Field data collected from March through October of 1980 were used to refine the
preliminary curve sets. Point measurements of depth, velocity, substrate, and temperature were
made at each fish location. HSC curves for depth, velocity, and substrate were produced for
spawning pink, chum, and coho salmon and Dolly Varden. Insufficient field data were collected
for development of site-specific curves for coho and Dolly Varden spawning. A total of 815
observations were made for pink spawning, 121 for chum spawning, 752 for coho fry, 199 for
coho juvenile, 460 for Dolly Varden fry, and 344 for Dolly Varden juvenile.
Lyons and Nadeau (1985) developed HSC curve sets for the Wilson River and Tunnel Creek,
which are located in the south-central part of the Misty Fjords National Monument, about 50
miles east of Ketchikan, Alaska. Both streams have steep topography, high drainage density,
shallow, porous and well-drained soils and large areas of exposed bedrock. These conditions
result in a “flashy” basin hydrology. Field sampling was conducted in August and October of
1984. The Wilson River watershed encompasses 116 square miles while the Tunnel Creek
watershed encompasses 9.9 square miles. The average annual discharge is 1,390 cfs in the
Wilson River and 68 cfs in Tunnel Creek. Pink and chum salmon are the most abundant fish
species present, though coho, Chinook, and sockeye salmon, steelhead, and Dolly Varden are
also present. Habitat data were collected for pink and chum salmon. While a large number of
measurements were made for pink salmon spawning, actual sample sizes are not reported. Depth
and velocity measurements were made for 27 spawning chum salmon. HSC curves for Chinook
and coho spawning, incubation, fry, and juveniles were based solely on pre-existing depth and
velocity curves.
Estes and Kuntz (1986) collected habitat utilization data for rearing juvenile Chinook salmon in
selected bank-type habitats of the Kenai River from the mouth to the outlet of Skilak Lake. Data
indicated that depth, velocity, and cover could be used to assess the usability of habitat for
juvenile Chinook. Velocity and cover appeared to be the most important in determining habitat
usability, though a set of “weighting factors” were developed all three habitat parameters.
More recently, PLP (2011) has developed HSC curves for several species inhabiting the North
and South Fork Koktuli rivers (Nushugak River tributaries) and Upper Talarik Creek (a Lake
Iliamna/Kvichak River tributary). HSC curves were developed using a combination of literature
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information and curve sets from other studies, as well as through collecting and analyzing site-
specific data for various target species and life stages. The collection of site-specific data
focused on collecting data related to spawning and juvenile rearing habitat use for salmon, and
adult rearing habitat use for resident salmonids. HSC data collected included microhabitat data
(depth, velocity, and substrate) over redds and at observed locations of juvenile and adult habitat
use from 2005 to 2008. HSC curves included the following species (and life stages): sockeye
salmon (spawning and juvenile), Chinook salmon (spawning and juvenile), coho salmon
(spawning and juvenile), and arctic grayling (adult).
6.2.2. HSC Data Set Comparisons
Vincent-Lang et al. (1984a) compared some of their findings with information available in the
literature. For chum salmon spawning, utilization data collected within the Susitna River
drainage were similar to the ranges summarized in a literature survey by Hale (1981). While
Hale (1981) did not develop criteria curves to which specific comparisons could be made, the
importance of upwelling groundwater to chum was emphasized which supported the binary
criteria developed for upwelling by Vincent-Lang et al. (1984a). Wilson et al. (l981) developed
suitability curves for chum salmon spawning that generally fell within the range of the Susitna
Basin curves, although some differences were found. Differences between these curve sets are
illustrated for depth (Figure 6.1-1) and velocity (Figure 6.1-2). For example, the chum salmon
velocity suitability curves developed for the Susitna River indicate a peak suitability in much
slower waters than do the Wilson et al. (1981) curves, although the upper limits of the two
curves only differed by 0.5 ft/s. Vincent-Lang et al. (1984a) suggest this difference may be
attributed to the fact that upwelling was not taken into account by Wilson et al. (1981). The
substrate suitability curves for chum salmon spawning for the two studies were similar, although
the Susitna River curve had a slightly wider range.
Vincent-Lang et al. (1984a) also reviewed information related to sockeye salmon spawning
criteria summarized in a literature review by the U.S. Fish and Wildlife Service (USFWS 1983).
The ranges of depth, velocity, and substrate conditions observed by Vincent-Lang et al. (1984a)
in sloughs and side channels of the middle Susitna River were within the ranges outlined in the
USFWS review. However, preference or suitability curves were not developed, limiting the
value of these comparisons. Curves developed for the North/South Fork Koktuli rivers and
Upper Talarik Creek (PLP 2011) were generally similar to those developed for the Susitna River
(Figure 6.1-7). However, the velocity curves were considerably different (Figure 6.1-8); optimal
velocities were much slower for the Susitna River curves. This difference may be related to the
importance of upwelling for sockeye spawning in the Susitna River. Curves for substrate had
similar optimal values, though a broader range of substrate size classes were deemed suitable for
the Susitna River curve (Figure 6.1-9). For juvenile sockeye, the PLP (2011) curves were
slightly different, showing higher suitability at greater depths (Figure 6.1-11), and slower
velocities (Figure 6.1-12).
For Chinook spawning, the depth curve developed by Vincent-Lang et al. (1984b) for the Susitna
River showed a slightly higher suitability for greater depths compared to the Wilson
River/Tunnel Creek curve (Lyons and Nadeau 1985) (Figure 6.1-13). However, the depth curve
for the North/South Fork Koktuli rivers and Upper Talarik Creek (PLP 2011) showed higher
suitability for greater depths. Spawning velocity curves (Figure 6.1-14) showed similar
deviations, with higher suitability for greater velocities compared to the North/South Fork
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Koktuli rivers and Upper Talarik Creek curve (PLP 2011), and lower suitability for slower
velocities compared to the Wilson River/Tunnel Creek curve (Lyons and Nadeau 1985).
Substrate suitability was generally similar (Figure 6.1-15) for the Susitna River curve and the
North/South Fork Koktuli rivers and Upper Talarik Creek (PLP 2011); the slight differences may
be a function of standardizing the different substrate classifications used in each study.
The Susitna River depth curves developed for juvenile Chinook salmon by Suchanek et al.
(1984a, 1985) showed a dramatic difference in suitability between the Middle and Lower River
and under turbid- and clear-water conditions. Suchanek et al. (1984a) also reviewed depth
criteria developed in other systems, noting that they varied significantly from the Susitna River
curves in which optimum depths were 1.0 to 1.5 ft in clear water and less than 0.5 ft in turbid
water. A depth probability-of-use curve described from Bovee (1978) showed an optimum range
from 1.2 to 3.0 ft, while described from Delaney and Wadman (1979) suggest an optimum of 2.5
to 3.2 ft. Findings from Burger et al. (1982) were reviewed in which Chinook fry were observed
in pools to ten ft deep and depths of less than 0.2 ft were thought to be avoided. The juvenile
Chinook depth curves for the North/South Fork Koktuli rivers and Upper Talarik Creek (PLP
2011) and the Wilson River/Tunnel Creek (Lyons and Nadeau 1985) both generally fall in
between the two Susitna River curves (Figure 6.1-16). The depth curve for the Kenai River, in
contrast, is nearly identical to the Lower Susitna River turbid-water curve.
The various velocity curves for juvenile Chinook are generally similar, showing a decrease in
suitability beyond an optimum of roughly 0.7 ft/s (Figure 6.1-17). Suchanek et al. (1984a)
reviewed information from Bovee (1978) and Burger et al. (1982), indicating a probability of
velocity utilization that was almost identical with the curve developed for clear water of the
Susitna River with the peaks at approximately 0.2 to 0.6 ft/sec. Minnow trap Chinook catch data
from the Little Susitna River was also compared (Delaney and Wadman 1979), and suggested an
optimum velocity for juvenile Chinook salmon from approximately 0.3 to 0.6 ft /sec, with little
use of velocities greater than 1.8 ft /s.
While coho spawning HSC data were not collected by Vincent-Lang et al. (1984b), the literature-
based curves for the Susitna River are generally in agreement with other studies. Suitability
reached an optimum at only a slightly greater depth (1.1 ft) for the North/South Fork Koktuli
rivers and Upper Talarik Creek (PLP 2011) compared to that chosen for the Susitna River
(Figure 6.1-18). Coho spawning velocity suitability was generally the same for all curves
considered (Figure 6.1-19). However, optimal substrates were larger for the North/South Fork
Koktuli rivers and Upper Talarik Creek curve (PLP 2011) (Figure 6.1-20).
For juvenile coho, Suchanek et al. (1984a) reviewed other studies in comparison to the Susitna
River. On the Terror and Kizhuyak rivers, for example, optimum depths for coho fry were cited
as from near 0.0 ft to 1.0 ft and then declining rapidly to zero at 2.5 ft (Baldrige 1981).
Suchanek et al. (1984a) also cited data from Bovee (1978) indicating very 1ittle use until 1.0 ft in
depth with an optimum at 2.0 ft and a gradual decline to zero use at 5.0 ft. In the Susitna River,
Suchanek et al. (1984a) reported an apparent optimum suitability at approximately 1.6 to 2.0 ft
with limited data above this depth. Based on these conflicting observations, Suchanek et al.
(1984a) concluded that depth suitability may vary greatly from river to river for unknown
reasons, but also suggested that the importance of depth may be highly correlated with other
habitat parameters. Thus, the selected depth curve for juvenile coho was fairly inclusive (Figure
6.1-21).
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Suchanek et al. (1984a) also reviewed other sources of information regarding juvenile coho
depth suitability, concluding that the optimum velocities derived for coho in the Susitna River
were very similar to velocity criteria developed for coho in other streams. This is also generally
consistent with the velocity suitabilities plotted in Figure 6.1-22.
6.3. Susitna-Watana HSC Studies
6.3.1. 2012 HSC Studies
Just like the Su-Hydro 1980s studies, one of the major components associated with completion
of the Susitna-Watana IFS will be the development and selection of species and life stage HSC
curves. This work was initiated in 2012 and will be continued in 2013-2014. The 2012 studies
were conducted over a three month period extending from July to September. Results of the
2012 surveys are presented below.
Importantly, there were no significant deviations or required revisions to the Final 2012 Instream
Flow Planning Study (March 20, 2012) related to the 2012 HSC data collection effort. The only
exception was the expansion of the proposed sampling area to include a portion of the Lower
River Segment (RM 95.4 to RM 77.0). HSC sampling within the lower river segment was added
when it became evident that IFS studies sites were being proposed for that area. As such, results
of 2012 HSC surveys are reported for both the Lower and Middle River segments of the Susitna
River. There were no changes to the timing or sampling methods proposed and utilized in
response to expansion of the 2012 sampling area.
6.3.1.1. Mainstem Susitna River Flow and Temperature – 2012
Discharge data for the Susitna River during the 2012 data collection period was obtained from
the USGS Gold Creek Station (USGS #15292000), located approximately 15 miles upstream of
Curry, Alaska (http://water.usgs.gov/). From 17 July to 19 September 2012, daily discharge
averaged 18,069 cubic feet per second (cfs) and ranged from a high of 29,600 cfs on 23 July to a
low of 10,200 cfs on 14 September (Figure 6.3-1).
Mainstem water temperature during this time period as reported at the Whiskers Creek
monitoring station ranged from a high of 16°C to a low of 5°C during the HSC sampling period
of mid-July to mid-September, 2012(Figure 6.3-2).
6.3.1.2. Preliminary Selection of Target Species and Life Stages
For the 2012 HSC sampling effort, a preliminary list of target fish species for sampling included
Chinook, coho, chum, and sockeye salmon; rainbow trout; arctic grayling; Dolly Varden; burbot;
longnose sucker; humpback whitefish; and round whitefish. These species are generally
considered the most sensitive to habitat loss through manipulation of flows in the Susitna River.
Other species and life stages will be considered in collaboration with the TWG.
6.3.1.3. Study Site Selection
The 2012 collection of microhabitat use data focused on mainstem, side channel, side slough,
and tributary delta habitat areas identified as having the highest abundance/use during the 1980s
surveys (Table 6.3-1). This information was used to define the relative proportion of species and
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life stages that utilize macro habitat types and the selection and use of species and life stage
specific microhabitat characteristics. The focus of the 2012 HSC curve sampling was on the
upper portion of the Lower River Segment and the Middle River Segment from the confluence
with Montana Creek upstream to near the proposed Watana Dam site.
The selection of study sites for the 2012 collection of HSC microhabitat data was based on
several factors including:
The distribution of the most highly utilized macrohabitat types (main channel, side
slough, side channel, tributary delta) by fish species and life stage;
Having good spatial representation of sampling sites within a segment;
Location of the sampling sites to proposed flow routing and IFS Focus Areas (see Section
3);
Prevailing flow conditions/visibility; and
Accessibility and safe sampling conditions.
Table 6.3-1 provides a summary of the species and life stages, macrohabitat types, study sites,
potential sampling techniques, and proposed sampling timing that was applied during the 2012
effort.
6.3.1.4. Field Data Collection
The 2012 HSC field effort focused primarily on collecting field measurements of microhabitat
use by different species and life stages. These data were then used to develop preliminary site-
specific HSC curves for comparison with the HSC curves developed during the 1980s studies.
Specific objectives of the 2012 field effort were to:
Provide HSC data collection training to field personnel from other AEA contractors
involved in fish studies to ensure uniformity in data collection efforts;
Collect microhabitat utilization data for selected target fish species and life stages;
Record different macro and mesohabitat types utilized by the different fish species and
life stages;
Recommend additional/new data collection techniques to be used during the 2013/2014
HSC data collection efforts.
The 2012 HSC field effort consisted of three separate sampling events completed during July
17–19, August 21–23, and September 17–19. During 2012 sampling, site-specific habitat data
were collected at 22 Middle River Segment sites located in tributary deltas, main channel, side
channel, and side slough macrohabitats between RM 178.0 and RM 101.4 (Table 6.3-2). In the
Lower River Segment, 11 sites were sampled in tributary deltas, side channel and side slough
habitats between RM 95.4 and RM 77.0 (Table 6.3-2). Site-specific observations were obtained
using visual means in clear water areas using snorkel and pedestrian surveys and pole/beach
seining methods in turbid water areas. Specific sampling methods utilized for each of these
methods is provided in subsequent sections.
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6.3.1.4.1. HSC Field Data Collection Training
To ensure consistent HSC data collection between field crews, field training sessions were held
with crew leaders from HDR (James Brady, HDR Alaska) and LGL (Sean Burril, LGL Alaska)
on July 17 and 19, 2012, respectively. Prior to the training sessions, standardized data collection
forms were developed and distributed to representatives from each firm for review and comment.
During the training sessions, field personnel from each firm reviewed the data collection forms,
equipment needs, sampling techniques, definition of terms, quality control checks, and data
storage and management procedures. HSC data collection efforts conducted by both LGL and
HDR were to be focused on macro and microhabitat use by spawning anadromous (LGL) and
resident fish species only. Data collection efforts by LGL were to be focused on the Middle
River Segment, while HDR was focused their efforts on the Upper River Segment.
6.3.1.4.2. Spawning/Redd Surveys
The timing and location of spawning/redd surveys was based in part on the periodicity data
developed from the 1980s data as well as from information obtained during radio telemetry
surveys conducted as part of fisheries studies (LGL 2012 Interim Draft Report). This
information was used to help identify sampling timing and areas with the highest concentration
of spawning activity for the five salmon species (sockeye, coho, Chinook, pink, and chum
salmon).
Although several different methods were used to identify the presence of spawning fish
(biotelemetry, pedestrian survey, and snorkel surveys), once an actively spawning fish or newly
constructed redd was identified in the field (Figure 6.3-3), the following measurements were
made:
Location of sample area on high-resolution aerial photographs and/or GPS location for
individual or groups of measurements
Species of fish occupying the redd or responsible for construction
Redd dimensions (length and width in feet to nearest 0.1 ft)
Water depth at upstream end of the redd (nearest 0.1 ft), using a top setting rod
Mean water column velocity (feet per second to nearest 0.05 fps), using a Swoffer current
meter
Substrate size (dominant, sub-dominant, and percent dominant) characterized in
accordance with a Wentworth grain size scale modified to reflect English units (Table
6.3-3)
Water temperature (to nearest 0.1 degree Celsius)
Indications of the presence of groundwater upwelling (changes in water clarity,
temperature, or visible upwelling)
Turbidity (using a portable turbidity meter) for each group of redds or in mainstem
habitat areas with relatively large concentrations of spawning fish (this information to be
used for comparison to measurements made during the 1980s survey)
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6.3.1.4.3. Snorkel Survey/Fish Observations
Snorkel surveys were conducted by a team of two or three fish biologists with extensive
experience in salmonid species identification. These surveys were conducted in conjunction
with adult spawner surveys at those areas identified in Table 6.3-1.
Prior to each survey, a Secchi disk reading was taken to determine the visibility corridor for
sampling. For this, a Secchi disk was held underwater by the data recorder, and a tape measure
extended by the snorkeler from the Secchi disk outward to a point where the disk is no longer
clearly visible (Figure 6.3-4). As a general rule, when visibility conditions were less than four
feet, no underwater sampling occurred. Water temperature was also recorded at the beginning of
each survey.
Starting at the lower/downstream point within a study area, the snorkelers proceeded in an
upstream direction making observations of all microhabitat types within their line of sight
(Figure 6.3-5). The following information was recorded for each observation:
Location of sample sites or areas marked on high-resolution aerial photographs and/or
GPS location recorded for individual or groups of measurements
Fish species observed
Assumed life stage (adult, juvenile, or fry)
Total fish length (estimated mm)
Number of fish observed
Mesohabitat type
Water depth (nearest 0.1 ft) using a top setting rod
Location in water column (distance from the bottom)
Focal point (location fish observed in the water column) and mean column velocity (feet
per second to nearest 0.05 fps) measured using a calibrated Swoffer current meter
Substrate size (dominant, sub-dominant, and percent dominant) characterized in
accordance with a Wentworth grain size scale modified to reflect English units (Table
6.3-3)
Proximity/affinity to habitat structure/cover features (e.g., boulder, wood debris, aquatic
vegetation, undercut bank, and overhanging vegetation)
Relevant comments pertaining to cover associations and/or behavioral characteristics of
the fish observed
All data were recorded on waterproof data sheets to ensure consistent data collection between
surveys. Only fish holding over a fixed position were included in the microhabitat survey.
Moving fish were not enumerated in order to minimize inaccurate habitat measurements, and to
prevent double-counting of fish.
6.3.1.4.4. Pole/Beach Seining
Pole seining was used in turbid water areas of all mainstem habitat types that could not be
sampled with underwater techniques due to visibility limitations. Pole seines used in this effort
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were 4 feet in depth and 40 feet in length, 3/16-inch mesh (net body) with a 1/8-inch mesh net
bag. The pole seine was operated with one person on each pole and the net was worked through
the sample area in an upstream direction (Figure 6.3-6). The seine contains a collection bag in
the middle to collect fish as they are directed into the net.
An attempt was made to sample fish from relatively small areas of approximately 15 feet by 15
feet with consistent depths, velocities, and substrates; however, exact size and dimensions were
sometimes changed to facilitate sampling larger areas of relatively uniform habitat or when fish
densities were expected to be low. The area (length and width) of each sampled area was
recorded on the field form.
Once captured, fish were identified to species, counted, and released in close proximity to the
capture site (Figure 6.3-7). For each area sampled, data collection was similar to that collected
during snorkel surveys with the exception of fish distance from the bottom and focal velocity.
Because no direct observation of the position of the fish in the water column can be made in
turbid water, fish position and focal velocity could not be recorded; a single depth and velocity
measurement was therefore recorded at a location with representative characteristics of the area
seined. All data were recorded on waterproof data sheets. Representative digital photographs
were taken of different macro and mesohabitat types where fish of different species and size
classes were observed.
6.3.1.5. Data Analysis
Prior to computation of HSC curves, the microhabitat data were entered into commercially
available spreadsheets and subsequently checked for data entry accuracy (QC 2). Any necessary
edits or corrections were then made to the database and checked by a senior staff member for
completeness (QC3). Frequency distributions were then generated for mean velocity, depth, and
substrate type for each species. Frequency bin widths of 0.2 were initially used to evaluate the
mean velocity and depth utilization distributions. Histogram plots of depth and mean column
velocity utilization were then produced for each species and life stage for which field
observations were recorded. A subset of HSC curves developed from the 2012 data were then
compared with HSC curve sets produced in the 1980s to see if patterns of use were similar. HSC
data collected by LGL for spawning fish/redds was reviewed for accuracy and incorporated into
the larger data set. No HSC data were received from HDR.
6.3.1.6. Results
A total of 284 observations of site-specific habitat use were recorded during 2012 HSC surveys
of the lower and middle segments of the Susitna River. Habitat measurements were obtained for
four different life history stages (spawning, juvenile, fry, and adult) and nine different fish
species including Chinook, sockeye, chum, coho, and pink salmon; rainbow trout; Arctic
grayling; humpback whitefish, and longnose sucker. As previously described, microhabitat
observations were concentrated in the Lower and Middle River segments of the Susitna River in
macrohabitat types where significant numbers of fish had been observed during the 1980s
studies. Figure 6.3-8 displays the relative location of the 2012 HSC observations collected by
both R2 and LGL. Spawning HSC observations were predominately made in the Middle River
Segment with only 17 of the 117 redd observations made in the Lower River Segment. The
number of HSC observations for the adult, juvenile, and fry life stages were split fairly equally
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between the Lower and Middle River segments with 69 observations in the lower river and 98 in
the middle river. A summary of results of the 2012 HSC data collection are presented below for
each of the eight species mentioned above.
6.3.1.6.1. Chinook Salmon
In 2012, no Chinook salmon were found spawning in the mainstem Susitna River (Table 6.3-4).
Radio telemetry surveys conducted by LGL indicated that adult Chinook were holding in the
main channel of the Susitna River, but there was no evidence that any of the 352 tagged fish
spawned in the main channel (LGL 2012). A total of 11 Chinook juvenile and 31 Chinook fry
microhabitat measurements were recorded, with nearly half (42.8%) of the total Chinook rearing
observations occurring in side channel macrohabitat areas (Table 6.3-5). Side slough and
tributary delta habitats had nearly equal numbers of observations with 12 and 11, respectively
(Table 6.3-5). Half of the Chinook salmon rearing observations occurred during the August 21-
23 sampling effort. Thirty-one percent were made during the mid-July sampling and the
remaining nineteen percent occurred during the mid-September sampling (Table 6.3-6).
Microhabitat depth measurements of Chinook fry utilization ranged from 0.5-1.9 feet with the
highest frequency occurring at a depth of 1.1 feet (Figure 6.3-9). For velocity, fry utilization
ranged from 0.1-1.7 feet per second (fps) with the highest frequency occurring at a velocity of
0.1 fps (Figure 6.3-9). Chinook juvenile were most frequently observed in slightly deeper water
with depths ranging from 0.5-2.1 feet with peak utilization occurring at a depth of 1.5 feet
(Figure 6.3-10). The range of observed velocity utilized by Chinook juvenile was also higher at
0.1-1.9 fps with the highest frequency occurring at velocities of 0.1 fps and 0.9 fps (Figure 6.3-
10). Although substrate utilization for both the fry and juvenile life stages of Chinook were
greatest for “fines” particle sizes (Table 6.3-3), some utilization was observed at nearly every
substrate size (Figures 6.3-9 and 6.3-10).
6.3.1.6.2. Sockeye Salmon
All of the 43 observations of sockeye spawning in the mainstem Susitna River were found in the
Middle River Segment in side slough macrohabitats (Table 6.3-4). Only six sockeye fry
microhabitat measurement were recorded, with all but one of the observations occurring in side
channel macrohabitat areas (Table 6.3-5). As expected, no juvenile sockeye were observed
during the HSC surveys as outmigration in the Susitna River occurs shortly after fry emergence
(Table 6.3-7 periodicity table). Although sockeye spawning was observed during all three of the
HSC surveys, the largest number of redd measurements occurred during the mid-September
sampling. All of the sockeye fry observations occurred during the mid-August sampling (Table
6.3-6).
Sockeye spawning depth utilization ranged from 0.7-2.3 feet with the highest frequency
occurring at 1.3 feet (Figure 6.3-11). For velocity, spawning utilization ranged from 0.1-1.5 fps
with the highest frequency occurring at a velocity of 0.1 fps (Figure 6.3-11). The low velocity
utilized by spawning sockeye is not surprising since all observations were made in side slough
macrohabitat areas with low mean column velocities. Substrate utilization ranged from sand to
small cobble with the highest frequency occurring in areas with medium gravel substrates (Table
6.3-3 and Figure 6.3-11). Water depths associated with the six sockeye fry ranged from 0.7-1.7
feet (Figure 6.3-12), whereas the range of water velocities was limited to 0.1-0.9 fps (Figure 6.3-
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12). Substrate utilization for sockeye fry was equally split between sand and small gravel
(Figure 6.3-12).
6.3.1.6.3. Pink Salmon
Spawning pink salmon (n=17) were found in both the Lower and Middle River segments with
the largest number of observations (n=14) occurring in tributary delta macrohabitats (Table 6.3-
4). No fry or juvenile pink salmon life stages were observed during the 2012 HSC surveys. The
absence of observations of rearing pink salmon is probably due to the early outmigration of
young fish prior to mid-August when the first 2012 HSC survey occurred (Table 6.3-7
periodicity table). All of the pink salmon spawning observations occurred during the mid-
August sampling (Table 6.3-6).
Pink salmon spawning depth utilization ranged from 0.5-1.9 feet with the highest frequency
occurring at 1.7 feet (Figure 6.3-13). For velocity, spawning utilization ranged from 0.5-3.1 fps
with the highest frequency occurring at a velocity of 2.5 fps (Figure 6.3-11). The relatively high
range of velocities utilized by spawning pink salmon is not surprising since most (14 of 17) of
the observations were made in tributary delta macrohabitat areas which generally have higher
mean column velocities than sloughs. Substrate utilization ranged from small gravel to small
cobble with the highest frequency occurring in areas with large gravel substrates (Table 6.3-3
and Figure 6.3-13).
6.3.1.6.4. Chum Salmon
Observations of chum salmon spawning were widely distributed in both the lower and middle
Susitna river segments with the largest number of observations (n=43) occurring in side slough
macrohabitats areas of the Middle River Segment (Table 6.3-4). Overall, chum spawning HSC
measurements were collected in six different side sloughs, two tributary deltas (n=4), and one
side channel (n=10) macrohabitat area. Eight chum salmon fry and no juvenile chum were
observed during the 2012 HSC surveys. Observations of chum fry were nearly equally split
between side channel, side slough, and tributary delta macrohabitat types. Chum salmon
spawning was observed during both the mid-August and mid-September 2012 HSC samplings
(Table 6.3-6).
Depth utilization by spawning chum salmon ranged from 0.3-4.3 feet with the highest frequency
occurring at 0.7 feet (Figure 6.3-14). For velocity, spawning utilization ranged from 0.1-2.5 fps
with the highest frequency occurring at the lowest measured velocity of 0.1 fps (Figure 6.3-14).
Like spawning sockeye salmon, the low velocities utilized by spawning chum is a result of most
of the microhabitat use observations being made in side slough macrohabitat areas which
generally have low mean column velocities. Substrate utilization ranged from fines to small
cobble with the highest frequency occurring in areas with large gravel substrates (Table 6.3-3
and Figure 6.3-14). For chum fry, water depth utilization ranged from 0.5-1.7 feet (Figure 6.3-
15). Water velocity utilization ranged from 0.1-1.3 fps with the highest frequency occurring at
0.1 fps (Figure 6.3-15). Substrate utilization for chum fry ranged from fines to large cobble with
the highest frequency of use found in areas with fine sediment (Figure 6.3-15).
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6.3.1.6.5. Coho Salmon
Like Chinook, there was no coho salmon spawning observed in the mainstem Susitna River
during the 2012 HSC surveys (Table 6.3-4). Although a total of 184 adult coho salmon were
radio tagged and their movement tracked as part of LGL’s adult salmon distribution study, there
was no evidence of spawning activity in the main channel of the river (LGL 2012). A total of 19
juvenile and 53 coho fry microhabitat measurements were recorded (Table 6.3-5). Coho fry
observations were nearly equally split with 24 measurements made in side slough habitats and 20
measurements in tributary delta macrohabitat areas (Table 6.3-5). For juvenile coho, side slough
and tributary delta habitats had equal numbers of observations with eight observations in each
(Table 6.3-5). The remaining three observations were made in side slough macrohabitats. Over
98 percent of the coho salmon rearing observations occurred during the mid-July and mid-
August sampling effort, with only one observation made during the mid-September sampling
(Table 6.3-6).
Microhabitat depth measurements for coho fry utilization ranged from 0.3-2.1 feet with the
highest frequency occurring at a depth of 0.9 feet (Figure 6.3-16). For velocity, fry utilization
ranged from 0.1-1.7 feet per second (fps) with the highest frequency occurring at a velocity of
0.1 fps (Figure 6.3-16). Coho juvenile were most frequently observed in slightly deeper water
with depths ranging from 0.9-2.1 feet with peak utilization occurring at a depth of 1.3 feet
(Figure 6.3-17). The range of observed velocity utilized by coho juvenile was slightly lower
than for fry at 0.1-1.3 fps with the highest frequency occurring at velocities of 0.1 fps (Figure
6.3-17). Although substrate utilization for both the fry and juvenile life stages of coho occurred
over a wide range of particle sizes, the frequency of use by both life stages has the highest for the
fines substrate size (Figure 6.3-17).
6.3.1.6.6. Arctic Grayling
Observations of arctic grayling were limited to the adult, juvenile and fry life stages as no
grayling spawning was observed. Although arctic grayling were observed in all four
macrohabitat types, only two of the 19 total observations were made in main channel
macrohabitat areas (Table 6.3-5). Arctic grayling observations were made in both the Lower and
Middle River segments. Eight of the 19 arctic grayling observations were for the adult life stage
and ten for the fry life stage (Table 6.3-5). No juvenile arctic grayling were observed during the
2012 HSC surveys. Arctic grayling microhabitat use observations were made during all three
sampling efforts (Table 6.3-6).
Depth utilization by adult grayling ranged from 1.5-3.1 feet with the highest frequency occurring
at 1.5 feet (Figure 6.3-18). For velocity, adult utilization ranged from 0.1-3.9 fps with the
highest frequency occurring at the lowest measured velocity of 0.1 fps (Figure 6.3-18). Substrate
utilization was limited to small and large cobble (Figure 6.3-18). Only one observation was
made for the juvenile life stage; depth was 1.1 feet and velocity was 0.3 fps (Figures 6.3-19 and
6.3-20). For grayling fry, water depth utilization ranged from 0.5-1.7 feet (Figure 6.3-20).
Water velocity utilization ranged from 0.1-1.7 fps with the highest frequency occurring at 0.1 fps
(Figure 6.3-20). Substrate utilization for grayling fry ranged from fines to large cobble with the
highest frequency of use found in areas with fine sediment (Figure 6.3-20).
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6.3.1.6.7. Rainbow Trout, Humpback Whitefish, and Longnose Sucker
A combined total of 20 HSC measurements were made for the other three species of fish
sampled during the surveys; rainbow trout, humpback whitefish, and longnose sucker (Table 6.3-
5). The lowest number of microhabitat measurements was for longnose sucker with only two
observations. No spawning observations were made for any of the three species. Seventy-
percent of the observations for these species occurred in side channel and tributary delta
macrohabitats (Table 6.3-5). None of the three species were detected during sampling of main
channel macrohabitat areas.
Adult rainbow trout and juvenile humpback whitefish were the only species and life stage
combinations with multiple HSC observations and so only those results are presented here. For
rainbow trout adult, depth utilization ranged from 0.9-3.1 feet and velocity utilization ranged
from 0.1-1.5 fps (Figure 6.3-21). Substrate utilization ranged from small cobble to boulder
(Figure 6.3-21). For juvenile humpback whitefish, depth utilization ranged from 1.1-1.5 feet,
and velocity utilization ranged from 0.1-1.1 fps (Figure 6.3-22). Substrate utilization for juvenile
whitefish ranged from fines to large cobble with the highest frequency of use found in areas with
fine sediment (Figure 6.3-22).
6.3.1.7. Recommendations for 2013 HSC Surveys
This TM summarized relevant information from the 1980s Su-Hydro studies and presented
preliminary results of the 2012 HSC surveys. One of the goals of the 2012 HSC surveys was to
evaluate the timing and distribution of HSC sampling efforts and the methods used for detecting
and measuring microhabitat use by different species and life stages of fish. The following are
preliminary recommendations based on results of the 2012 surveys that are designed to help
refine the 2013 surveys. It is expected that these recommendations will be discussed and refined
during TWG meetings planned for Q1 2013.
Coordinate with LGL to better identify the beginning of the upstream migration period
for each fish species by reviewing fish wheel capture records. Initiate spawning/redd
surveys immediately following reports of fish wheel capture of adult fish.
Work closely with LGL to utilize the results of real-time radio telemetry surveys of adult
fish to assist in determining the timing and use of different macrohabitat types.
Coordinate HSC spawning/redd sampling to take full advantage of real-time habitat use
information obtained from the radio telemetry surveys.
Review testing results of use of side-scan and DIDSON sonar to detect spawning in
turbid main channel and side channel macrohabitat types completed by LGL in
September 2012. If these methods show promise for detecting spawning in turbid water
areas, work with LGL to expand the use of these methods to both lower and middle river
segments to identify spawning/redd areas for microhabitat measurements.
Based on results of 2013 Winter Pilot studies, include winter surveys of microhabitat use
at a representative subset of the IFS Focus Areas. If possible, incorporate nighttime HSC
surveys to detect any variations in diurnal microhabitat use by juvenile fish.
Pursue the use of electrofishing techniques to determine meso and microhabitat use of the
target species and life stages in turbid water areas. Although the use of stick seining does
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appear effective in capturing fish in turbid water areas, use of this method is somewhat
restricted to areas with shallow depth (<4 ft), low velocity, and small substrate sizes.
Utilizing results of mainstem habitat mapping, conduct systematic sampling of all
representative macro and mesohabitat types within each of the IFS Focus Areas. Special
effort should be made to ensure that HSC sampling occurs within each of the main
channel mesohabitat types present. The proposed number and distribution of 2013 HSC
sampling sites will be presented to the TWG during the Q2 2013 meeting.
Increase the frequency, duration, and distribution of summertime HSC surveys to detect
potential difference in microhabitat use by different species and life stages based on
spatial and/or temporal variability. HSC sampling crews will work closely with fish
distribution surveys to ensure that sampling priority can be given to those macro and
mesohabitat types that support the largest diversity and number of fish.
Continue to build HSC database utilizing site-specific microhabitat observations. Utilize
database to identify relationships between macro, meso, and microhabitat use by target species
and life stages as well as differences in use of clear water versus turbid water and areas with and
without groundwater upwelling.
6.3.2. Proposed 2013-2014 Studies
The HSC surveys completed in 2012 provided an initial opportunity to test various gear sampling
techniques and to collect a preliminary set of microhabitat data. The results of those surveys will
be useful in refining and implementing the more rigorous HSC data collection program in 2013-
2014 as specified in RSP Section 8.5.2.1.5.
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7. TECHNICAL MEMORANDUM – REVIEW OF HABITAT MODELING
METHODS APPLICABLE FOR THE SUSITNA RIVER
Instream flow studies invariably result in the collection of copious amounts of data that are
typically evaluated via application of one or more models. These can range from empirically
derived models such as those derived from expert habitat mapping (Railsback and Kadvany
2008) to more sophisticated methods involving a suite of hydraulic and habitat models such as
are available via the Physical Habitat Simulation (PHABSIM) package of programs that is often
referenced as part of the Instream Flow Incremental Methodology (IFIM) (Stalnaker et al. 1995;
Bovee 1982). There are many other methods that have been developed and used as part of
instream flow studies, some of which are described below, while others can be found in
reference documents such as those of Annear et al. (2004), Locke et al. (2008) and others. This
TM first describes the types of models that were used as part of the 1980s Su-Hydro studies and
then summarizes the methods and models that are being proposed as part of the 2013-2014
Susitna-Watana IFS studies.
7.1. Su-Hydro 1980s Studies
The instream flow studies completed during the 1980s were conducted in the Middle and Lower
River segments of the Susitna River downstream of Devils Canyon. Studies during the 1980s
were designed to evaluate changes in fish habitat relative to changes in mainstem Susitna River
discharge, and employed a variety of techniques that included hydraulic and/or habitat modeling
and habitat mapping. In the Middle River, modeling and mapping efforts were performed at 36
sites between River Mile6 (RM) 148 and RM 101 during 1983 and 1984 (Table 7.1-1, Figures
7.1-1 and 7.1-2). In the Lower River, hydraulic and habitat modeling was completed at 20 sites
between RM 92 and RM 35 (Table 7.1-1). Fish habitat availability at different locations was
modeled over a range of Susitna River discharges using one or more of the following habitat
models: IFIM –IFG3 (HABTAT), Direct Input Habitat (DIHAB), and Resident Juvenile Habitat
(RJHAB). The IFIM HABTAT model was used in conjunction with Instream Flow Group (IFG)
hydraulic models (IFG-4), whereas no hydraulic modeling was completed in association with
DIHAB or RJHAB models. In addition to these modeling techniques, two-dimensional mapping
was used to quantify available habitat at tributary mouths and extrapolation analyses were
proposed that were designed to project modeling results to non-modeled areas throughout the
Susitna River.
Habitat model selection during the 1980s studies was based on site-specific channel and
hydrologic characteristics, the desired resolution of microhabitat simulation, and the field
logistics associated with each method. The output provided by IFIM HABTAT, DIHAB, and
RJHAB habitat models was generally similar to that provided by the habitat mapping method
used at tributary mouths. Each method characterized changes in fish habitat by relating the
amounts of wetted surface area and wetted usable area for juvenile and adult fish to Susitna
River discharge. More detail concerning each of the methods applied in the 1980s is provided
below. More specific information concerning overall locations of methods application including
numbers of transects and flows measured can be found in Appendix 3.
6 River mile designations are those used in the 1980s studies and designated within R&M (1981a).
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7.1.1. PHABSIM Models
7.1.1.1. Description
The PHABSIM group of models were developed in the late 1970s and early 80s by the USFWS
Instream Flow Group (IFG) in Fort Collins, Colorado (Milhous et al. 1984; Bovee and Milhous
1978). For this reason, many of the models coined the prefix of IFG as part of their description;
e.g., IFG-2, IFG-3, IFG-4 etc.). These models include both hydraulic and habitat models and are
commonly used within the IFIM as a means to predict changes in fish habitat quantity relative to
incremental changes in stream discharge. In the 1980s, all of the hydraulic models were one-
dimensional (1D) models with their vector orientation uni-directional. The IFG models are
generally suitable in areas characterized by steady or uniform flow conditions and rigid stream
channels and where stream flow is assumed to be the primary determinant of fish habitat quality
(Trihey 1979; Hilliard et al. 1985). The IFG hydraulic models predict conditions (i.e., water
depth and velocity) within a stream section over a range of discharges based on measurements
recorded at points along multiple transects. Water depth, velocity, substrate and cover conditions
are recorded at each transect measurement point at multiple discharge levels. Within the IFG
model, each measurement point is a cell within which mean depth and velocity and substrate and
cover conditions are assigned based on measured values. The wetted surface area of the cell is
calculated within the model based on measurement point spacing.
The output of the hydraulic models are entered into habitat models (e.g., HABTAT) with
additional data pertaining to habitat parameter preferences (e.g., depth, velocity, substrate, cover)
of individual fish species and life stages to obtain an index of fish habitat area (Weighted Usable
Area [WUA]). Habitat preferences often vary among fish species and life stages and are
characterized for each target fish and/or life stages (see Section 6). Within measurement cells,
the fish/life stage preference values for each habitat variable are multiplied with the cell area to
obtain a weighted area for that cell. All transect cells are summed to provide the total weighted
useable area (WUA) at the measured discharge. The final model results depict WUA
(normalized to 1,000 square feet of stream) versus flow relationships by species and life stage.
7.1.1.2. Summary of Results
During the 1980s Su-Hydro instream flow studies, IFG and HABTAT models were used to
model changes in juvenile fish habitat with flow at 15 sites in the Middle Segment during 1983
and 1984 and at 6 sites in the Lower River in 1983 (Table 7.1-1; Appendix 3) (Vincent-Lang
1984b, Hilliard et al. 1985, Suchanek et al. 1985). IFG modeling sites in the Middle and Lower
River segments were located in side channel and side slough habitats (no main channel habitats
were modeled with PHABSIM) and were primarily used to describe changes in rearing habitat
for juvenile Chinook salmon, although they were also applied to juvenile sockeye and chum
salmon (Hilliard et al. 1985, Suchanek et al. 1985). Examples of IFG transect locations in
various side channel habitats in the Middle Susitna River are depicted in Figure 7.1-3 and Figure
7.1-4. At IFG sites in the Middle River segment, data were measured at Susitna River discharge
levels ranging from approximately 6,000 cfs to 22,000 cfs (USGS Gold Creek gaging station,
RM 136.6) and juvenile Chinook rearing habitat area was modeled at discharge levels ranging
from 5,000 cfs to 35,000 cfs (Hilliard et al. 1985). In the Lower River, IFG models were used to
model changes in juvenile Chinook, sockeye, and chum habitat at Susitna River discharge levels
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ranging up to approximately 60,000 cfs to 70,000 cfs (USGS Sunshine gaging station, RM 83.9)
(Suchanek et al. 1985).
In the Middle Segment, WUA for juvenile Chinook at IFG sites was positively and negatively
associated with Susitna River discharge among sites (Hilliard et al. 1985). Habitat area at lower
discharge levels was typically limited by depth, while at higher flows negative trends in WUA
were attributed to increased water velocity (Hilliard et al. 1985). In the Lower River, Susitna
River discharge was a very important factor in determining habitat conditions in side channels
and side sloughs (Suchanek et al. 1985). For example, suitable habitat for juvenile Chinook
salmon typically increased as side channel and slough habitats became breached by increasing
Susitna River discharge, but WUA decreased at elevated discharge levels due to unsuitable
turbidity and water velocity levels (Suchanek et al. 1985).
7.1.2. Direct Input Habitat (DIHAB) Model
7.1.2.1. Description
The DIHAB model was created by Trihey and Associates during the 1980s Su-Hydro studies for
stream reaches that were not compatible with IFG model assumptions of steady, or gradually
varied streamflow conditions (Hilliard et al. 1985). Sites in which the DIHAB model was
applied were characterized by very low and spatially varied water velocities (Hilliard et al.
1985). In the Susitna River, such areas were often located on stream margins or in areas affected
by backwater from the Susitna River main channel (Hilliard et al. 1985).
The DIHAB model was used to evaluate changes in fish habitat based on habitat conditions
measured at points on multiple transects and at two or more Susitna River discharge levels. Data
collection for DIHAB models was similar to that of IFG models, but differed in that the presence
or absence of upwelling at each site was recorded in addition to water depth, current velocity and
substrate data. Upwelling presence was a binary variable (i.e., present, not present) in DIHAB
models. In contrast to IFIM models, DIHAB models did not incorporate hydraulic models;
changes to fish habitat area over the range of empirically measured stream flows was estimated
using hydraulic and channel geometry data.
The output provided by the DIHAB model was similar to that supplied by the IFG and HABTAT
models in that changes in preferred fish habitat in terms of WUA or other habitat metrics were
presented relative to Susitna River discharge. As noted, the DIHAB model does not incorporate
hydraulic modeling, so WUA or other habitat indices were estimated by linear interpolation for
discharge values that were not directly measured but were within the range of measured
discharges (Hilliard et al. 1985).
7.1.2.2. Summary of Results
The DIHAB model was applied at 14 sites in the Middle River segment on main channel margins
and side channels in 1984 (Table 7.1-1; Appendix 3) (Hilliard et al. 1985). DIHAB modeling
during the 1983 studies targeted adult chum salmon spawning which often occurred in areas with
low and/or variable current velocity and groundwater upwelling (Hilliard et al. 1985). An
example of DIHAB transects location in mainstem margin and side channel habitat in the Middle
Susitna River is depicted in Figure 7.1-4. Among the 14 Middle Segment sites, measured
discharge levels ranged from approximately 7,500 cfs to 20,000 cfs (USGS Gold Creek gaging
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station, RM 136.6) and habitat conditions were modeled between Susitna River discharges of
5,000 cfs and 25,000 cfs (Hilliard et al. 1985).
In general, WUA (habitat) for adult chum spawning at backwater sites was positively associated
with discharge until water depth was not limiting to chum spawning preference, at which point
WUA flattened (Hilliard et al. 1985). In contrast, adult chum spawning WUA in mainstem
margin areas was negatively associated with Susitna River discharge, as higher velocities limited
suitability for chum spawning (Hilliard et al. 1985). In side channel habitats, trends in WUA
were positive at lower discharge levels but became negative as velocities exceeded spawning
preference values at higher discharges (Hilliard et al. 1985). In all areas, the amplitude of the
WUA curve was positively associated with presence of upwelling and substrate quality (Hilliard
et al. 1985).
7.1.3. Resident Juvenile Habitat (RJHAB) Model
7.1.3.1. Description
The RJHAB habitat model was a simplified means of estimating changes in fish habitat without
using hydraulic models. Data collection methods for the RJHAB were generally similar to that
of the DIHAB model, although measurement points on each transect were apportioned
differently. For the RJHAB model, multiple cross-sections were established and two shoreline
cells and one mid-channel cell were created for each transect at each site (Figure 7.1-5). In each
cell, the mean values for water depth, current velocity, substrate, and cover were recorded.
WUA (habitat) was calculated for each cell and the total site WUA was derived from the sum of
WUA from all shoreline and mid-channel cells among all transects at the site (Marshall et al.
1984). WUA was calculated only for measured discharge levels, so WUA was interpolated for
intervening discharges and extrapolated for flow conditions outside the measured range
(Suchanek et al. 1985).
7.1.3.2. Summary of Results
RJHAB modeling was applied at six side channel, side slough, and upland slough sites in the
Middle Segment in 1983 and at 16 side channel, side slough, and tributary mouth sites in the
Lower River in 1984 (Table 7.1-1; Appendix 3) (Marshall et al. 1984; Suchanek et al. 1985). An
example of RJHAB transect location in side slough habitat in the Middle Susitna River is
depicted in Figure 7.1-4. RJHAB modeling in the Middle and Lower River segments targeted
juvenile Chinook, sockeye, chum and coho salmon rearing habitat (Marshall et al. 1984;
Suchanek et al. 1985). Model measurements in the Middle River segment were recorded at
Susitna River discharges ranging from approximately 10,000 cfs to 30,000 cfs (USGS Gold
Creek gaging station, RM 136.6) and WUA were calculated for discharge levels between 5,000
cfs and 45,000 cfs (Marshall et al. 1984). RJHAB modeling in the Middle River segment
indicated that in side channel habitats, WUA peaked during a narrow range of flows that
occurred following breaching of the side channel (Marshall et al. 1984). In side and upland
sloughs, WUA was affected by backwater effects from the Susitna River main channel (Marshall
et al. 1984). At all habitat types, WUA was strongly affected by cover (Marshall et al. 1984).
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7.1.4. Habitat Mapping
7.1.4.1. Description
Two-dimensional habitat mapping was conducted at tributary mouths in the Middle River
segment in 1983 to characterize changes in habitat independently of hydraulic modeling
(Sandone et al. 1984). The habitat mapping method targeted adult chum spawning at the
confluences of 4th of July Creek (RM 131.1) and Lane Creek (113.6) with the Susitna River main
channel (Table 7.1-1). The two tributary mouth sites were considered to be representative of the
14 major tributary confluences in the Middle Segment (Sandone et al. 1984). Water depth,
velocity and substrate data were collected at points on multiple transects and at several discharge
levels (Sandone et al. 1984). These data were used to create two-dimensional parameter-specific
maps delineating the area of suitable chum spawning habitat. The three separate parameter-
specific maps were then overlaid to identify the composite area of habitat suitability that was
available at each measured flow level (Sandone et al. 1984).
7.1.4.2. Summary of Results
Habitat mapping was conducted at four separate Susitna River stream flows ranging from
approximately 8,000 cfs to 24,000 cfs (USGS Gold Creek gaging station, RM 136.6). Results of
the mapping exercise indicated a positive association between usable habitat area at 4th of July
Creek (RM 131.1) and Susitna River discharge, while at Lane Creek (RM 113.6) the relationship
was slightly negative (Sandone et al. 1984).
7.1.5. Aerial Photography Interpretation – Habitat Surface Area Mapping
7.1.5.1. Description
In addition to methods that involved field data collection, the Su-Hydro instream flow studies
also utilized aerial photography interpretation as a means to identify and map aquatic habitat
types in the Susitna River under different flow conditions. Separate analyses were completed for
the Middle River (Klinger-Kingsley et al. 1985) and Lower River (R&M Consultants et al. 1985)
but both employed similar analytical techniques. These generally included completion of aerial
photography of each of the river sections under different flow conditions and then identifying,
delineating and digitizing specific habitat types (see Section 3) occurring within specific
segments of the river under each of the flow conditions. This provided the ability to plot habitat
areas (of specific habitat types) versus flow conditions for the different habitat types which could
then be rolled up to provide estimates of total surface areas by habitat type for the entire river
corridor (for the Middle River) or river segments (for the Lower River).
7.1.5.2. Summary of Results
Analysis of the Middle River involved aerial photo interpretation of photographs taken at
mainstem discharges of 23,000 cfs, 16,000 cfs, 12,500 cfs and 9,000 cfs (Klinger-Kingsley et al.
1985), along with surface area measurements taken at four other discharges; 18,000 cfs, 10,600
cfs, 7,400 cfs, and 5,100 cfs. The analysis allowed for an interpretation of habitat
transformations as flows change which are well depicted in the series of photo plates presented
in Trihey and Associates (1985).
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Analysis of the Lower River involved aerial photo interpretation of photographs taken at 75,200
cfs, 59,100 cfs, 36,600 cfs, 21,100 cfs, and 13,900 cfs. Because of the complexity of the Lower
River, the analysis was organized into different river segments and habitat types were delineated.
Representative areas were then identified for which habitat types would be mapped and wetted
surface areas measured. These included; Side Channel IV-4 located within RMs 32.5-36;
Willow Creek Side Channel located within RMs 49-52; Caswell Creek – RM 64, Sheep Creek –
RM 66.1, Goose Creek Side Channel located within RMs 689.5-72.5, Montana Creek Side
Channel located within RMs 77-78, Sunshine Slough Side Channel located within RMs 84-86.5
and Birch Creek Slough located within RMs 88.5-93 (R&M Consultants et al. 1985). More
details concerning the Lower River analysis can be found in Tetra Tech (2013).
7.1.6. Extrapolation Analyses
7.1.6.1. Description
Extrapolation of habitat modeling results from modeled sites to non-modeled areas is typically
performed as part of habitat analyses to evaluate the response of fish habitat quantity and/or
quality in the entire stream system to discharge levels (Aaserude et al. 1985). During
extrapolation analyses, it is important to assess the representativeness of modeled sites to non-
modeled areas. Extrapolation is typically applied as part of IFIM in stream segments that exhibit
homogenous hydrologic, hydraulic and morphological characteristics (Bovee 1982). Modeling
results obtained within a reach that is representative of a homogenous segment can then be
applied to non-modeled areas in the segment on a proportional length basis (Bovee 1982). In
single-thread rivers, it is possible to derive a system-wide response of habitat change relative to
discharge using this method (Bovee 1982, Aaserude et al. 1985). In braided or multiple-thread
rivers such as the Susitna River, extrapolation of modeling results based on this method cannot
always be done reliably (Mosley 1982). Although multiple-thread rivers can be divided into
homogenous segments, it is often not possible to extrapolate hydraulic characteristics laterally
across braided channels, which are frequently quite variable and highly dynamic (Mosley 1982).
The extrapolation methods developed during the 1980s modeling studies for the multiple-thread
Susitna River differed from that of IFIM extrapolation techniques in three important ways (Table
7.1-2) (Aaserude et al. 1985, Klinger-Kingsley et al. 1985, Steward et al. 1985). First,
extrapolation from modeled sites to non-modeled areas was performed based on proportional
area rather than a proportional length basis to reflect the greater variability in channel widths in a
multiple-thread system relative to a single channel stream (Table 7.1-2) (Aaserude et al. 1985).
Secondly, Aaserude et al. (1985) noted another distinction between single- and multiple-thread
rivers was that although morphologically similar areas existed in braided rivers, these areas never
occurred within a continuous homogenous segment (Table 7.1-2). Areas that were
morphologically similar were termed ‘Representative Groups’ by Aaserude et al. (1985), and
were identified by an approach that consisted of comprehensive reconnaissance level surveys in
addition to intensive study reaches where modeling occurred. A third primary difference
between traditional IFIM and 1980s Susitna River extrapolation techniques was that results from
1980s modeled sites applied to non-modeled areas were adjusted to account for the greater
degree of variability in structural habitat in a multiple-thread river system relative to that
typically present in a single-thread river (Table 7.1-2) (Aaserude et al. 1985). Areas that are
similar in terms of hydrology and/or hydraulics may exhibit disparate structural attributes that
affect fish habitat quality (Aaserude et al. 1985).
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7.1.6.2. Summary of Results
Extrapolation analyses were developed as part of the 1980s habitat modeling studies as a means
to expand habitat-streamflow relationships developed at modeled sites to non-modeled sites. As
a basis, habitats were characterized in terms of hydrologic (e.g., side channel breaching flow),
hydraulic (e.g., water depth, velocity, groundwater upwelling), and structural cover (i.e.,
vegetation, debris, and/or substrate) attributes over a range of stream discharge levels using
aerial photography and aquatic habitat survey data (Aaserude et al. 1985). Representativeness
between modeled and non-modeled sites was evaluated using these data (Aaserude et al. 1985).
All habitat types (e.g., mainstem, side channel, side slough, upland slough) throughout the
Middle River segment were characterized, except tributary areas, at multiple discharge levels.
The methodology used by Aaserude et al. (1985) consisted of quantification, stratification, and
simulation pathways. A preliminary step of quantification was to delineate areas of homogenous
habitat types (e.g., mainstem, side channel, side slough, upland slough) using aerial photos (see
Klinger-Kingsley et al. 1985). The response of habitat surface area to changes in discharge was
measured for each habitat over several discharge levels (Klinger-Kingsley et al. 1985). Wetted
surface area (WSA) was used as the metric of habitat quantity for this exercise (Aaserude et al.
1985, Klinger-Kingsley et al. 1985).
The stratification pathway classified delineated habitats into similar groups and provided a
means to associate modeled and non-modeled areas. Each habitat area was classified into
Representative Groups, based on hydrologic, hydraulic and structural characteristics (Table 7.1-
3). Important hydrologic features used to classify habitats included breaching flow, the presence
and extent of groundwater upwelling, and the transformational response of the habitat to changes
in Susitna River discharge (Aaserude et al. 1985). Primary hydraulic characteristics used to
distinguish Representative Groups were mean channel current velocity, dominant substrate type,
and channel morphology, as an index of site hydraulics (Aaserude et al. 1985). Structural cover
conditions in each habitat area were used in conjunction with cover suitability data for individual
fish species and life stage to derive a Structural Habitat Index (SHI). The SHI was used to
associate a modeled habitat area with non-modeled areas and was not intended to be an index of
overall habitat quality (Aaserude et al. 1985).
The simulation pathway consisted of hydraulic and/or habitat modeling at representative habitats,
which predicted the relationship between habitat area and Susitna River discharge. Habitat
models used as part of this exercise consisted of the IFG/HABTAT, DIHAB, and RJHAB
models. The available habitat at each modeled streamflow was represented as WUA.
For extrapolation of modeled results to non-modeled sites, a Habitat Area Index (HAI) was used
to represent the response of available habitat relative to stream discharge for a given habitat type
and was calculated as the quotient of WUA and WSA (Aaserude et al. 1985). Modeled results
were extrapolated using the HAI at the modeled site and representative grouping, breaching
flows, and SHI at the modeled and non-modeled habitat areas (Aaserude et al. 1985). During
extrapolation, HAI were adjusted for differences in breaching discharge and SHI between
modeled and non-modeled areas (Figure 7.1-6). Assumptions of the extrapolations included: 1)
HAI curves of modeled areas were representative of non-modeled areas within the same
Representative Group, 2) breaching flows appear on the same relative position on HAI curves,
and 3) linear adjustment of HAI versus discharge curve amplitude can be derived for non-
modeled areas using the ratio of SHIs for modeled and non-modeled areas (Aaserude et al.
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1985). Once relationships were derived from un-modeled areas, it was then possible to integrate
results into an overall assessment of habitat-flow responses within each representative group;
these were presented in Steward et al. (1985). The next proposed step in the extrapolation
process would have been to conduct a system-wide (at least for the Middle River segment)
evaluation of habitat-flow responses that would have aggregated the responses into a system-
wide habitat-flow response relationship. However, that step was never completed as part of the
1980s studies since the project was cancelled.
7.2. Susitna-Watana 2013-2014 Studies
There have been substantial advances in the development and application of instream flow
methods and models since the 1980s and many of these new tools are being proposed for use as
part of the 2013-2014 Susitna-Watana IFS program. Of particular note is the proposed
application of two dimensional hydrodynamic modeling for much of the work. Two-
dimensional models (2-D) were not available in the 1980s and therefore it was not possible to
model large, contiguous sections of the river over a wide range of flows. Indeed, habitat – flow
modeling of the main channel of the Susitna River was not even attempted during the 1980s
studies. As a point of reference, Personal Computer (PC) development was just in its infancy so
that data entry, data analysis and modeling was largely handled as a post-field activity and likely
often involved main-frame computer systems.
Data collection instrumentation has likewise improved and has facilitated the application of 2D
models. Most notably the advent of the Acoustic Doppler Current Profiler (ADCP) allows for
the measurement and recording of a velocity array that spans the majority of the entire water
column across a river cross-section efficiently, safely, and relatively quickly. Coupled with Real
Time Kinematic (RTK) Global Positioning Satellite (GPS) survey instruments and bathymetric
sonars, this suite of instruments now allows for the collection of accurate river bed topography in
relatively long reaches of large river systems. These data allow for development of 2D
hydrodynamic models that can be used not only for evaluating habitat –flow relationships via a
PHABSIM analysis, but also for sediment transport modeling and fluvial geomorphological
analysis. Contemporary software packages allow for much more detailed and complex analysis
of large amounts of data than was possible in the 1980s and when linked within a Geographical
Information System (GIS) framework, provide the ability for large-scale detailed spatial
depiction of information. The IFS methods proposed for 2013-2014 will rely on many of these
new technologies and analytical tools. Those methods have been presented in RSP Section 8.5
with portions reproduced here for convenience and to allow comparison with approaches applied
in the 1980s.
7.2.1. Target Range of Flows
In conventional instream flow studies involving field data collection, one of the initial planning
activities relates to the identification of a target range of flows that are of interest in terms of
modeling and field data collection. These flows typically represent the range of flows over
which project operations would have a notable effect and that would occur during biologically
sensitive periods. The objective then is to collect sufficient data and information that would
allow the development of models and analytical tools that can evaluate habitat conditions over
the range of operational flows that may occur during those biologically sensitive periods.
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During the 1980s studies, ranges of flows were identified for both the Middle River (5,000 cfs to
23,000 cfs) and Lower River (≈ 13,000 cfs to ≈ 75,000 cfs) segments as part of the habitat
surface area analysis completed by Klinger-Kingsley et al. (1985) and R&M Consultants et al.
(1985). As noted by Klinger-Kingsley et al. (1985), the discharge range for the Middle River
was assumed to be adequate for identifying the transformation of areas from one type of habitat
to another as a result of reductions in flow due to project operations, and the range of flows
highlighted for the Lower River was presumably selected with that in mind.
For the 2013-2014 studies, these same general ranges of flow will likely serve as targets for the
two respective segments. Recent results of hydrological analysis completed by Tetra Tech
(2013) provide a comparison of average annual and monthly flows under Pre- and Post – project
operations at four gage stations in the Middle and Lower segments of the river. Those data along
with results of the open-water flow routing model (R2 et al. 2013), other hydrologic information
(e.g., monthly exceedance flows for the Susitna River at Gold Creek (USGS No. 15292000)
(Figure 7.2-1), an evaluation of channel characteristics and habitat types and their sensitivity to
flows, and the periodicities of the target fish species and life stages will be used to identify
appropriate ranges of flows for analysis within the two river segments. In conventional
PHABSIM modeling, a rule of thumb for extrapolation of 1D hydraulic models is that the range
of extrapolation can extend 0.4 x the lowest measured flow and 2.5 x the highest measured flow.
Based on that convention, the range of target flows identified above would provide an
extrapolation range generally within the flow ranges found under Pre-project hydrologies.
However, it should be noted that there is no convention regarding the range of extrapolation for
the 2-D hydrodynamic models which are being proposed for application in the FAs.
7.2.2. Habitat Model Selection
Identifying and quantifying the predicted changes in aquatic habitat in the Middle and Lower
segments of the Susitna River under the proposed Project operational scenarios will require the
use of several different hydraulic and biological models. Each of the models proposed for use
has been selected to assist in the evaluation of the physical and biological effects of the proposed
Project. Development of these models will require careful evaluation of existing data and
information as well as focused discussions with technical representatives from the TWG. These
models will rely in part on information and technical analyses performed in other study
components as a basis for developing model structures (e.g., Habitat Mapping; other riverine
process studies).
As noted above, physical habitat models are often used to evaluate alternative instream flow
regimes in rivers (e.g., the Physical Habitat Simulation [PHABSIM] modeling approach
developed by USGS; Bovee 1998; Waddle 2001). Methods available for assessing instream flow
needs vary greatly in the issues addressed, their intended use, their underlying assumptions, and
the intensity (and cost) of the effort required for the application. Many techniques have been
used, ranging from those designed for localized site or specific applications to those with more
general utility. The summary review reports of Wesche and Rechard (1980), Stalnaker and
Arnette (1976), EA Engineering, Science and Technology (1986); the proceedings of the
Symposium on Instream Flow Needs (Orsborn and Allman eds. 1976); Electric Power Research
Institute (2000); and more recently the Instream Flow Council (Annear et al. 2004 and Locke et
al. 2008) provide more detailed information on specific methods. The methods proposed in the
IFS include a combination of approaches that vary depending on habitat types (e.g., mainstem,
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side channel, slough, etc.) and the biological importance of those types, as well as the particular
instream flow issue (e.g., connectivity/fish passage into the habitats, provision of suitable habitat
conditions in the habitats, etc.). Field efforts will be concentrated within Focus Areas (within the
Middle Segment) and at representative habitat types (within the Lower Segment) and will entail
collection of data suitable for 2-D modeling (Middle Segment) and 1D modeling (Lower
Segment) as well as other analysis. Of particular note is that the models and analysis include a
directed effort toward evaluating potential project effects of load following and the resulting
fluctuations in flow that can occur on a daily basis. This type of analysis was not needed during
the 1980s studies since the project configuration involved two dams one of which was a re-
regulating dam. Thus, project operations in the Middle River were proposed as baseload
operation and such effects (i.e., daily/hourly flow fluctuations) were not anticipated. The overall
methods proposed for the 2013-2014 studies are described in more detail in RSP Section
8.5.2.1.8 and are summarized below.
Development of the models that will be used in the 2013-2014 studies will involve coordination
with other resource studies and consultation with the TWG. Once final study areas (Focus
Areas) and transects/study segments have been identified, proposed methods of analysis and
modeling will be reviewed with the TWG. The models will be tailored based on habitat types to
be measured and the selected models to be used. This will involve a combination of 1-D and 2-
D modeling approaches and may also involve application of empirically-based methods. Table
7.2-1 provides a listing of potential models/methods that will be considered as part of the IFS.
The most appropriate methods for selected study areas will be determined via careful review of
site conditions and the underlying questions needing to be addressed.
The following section provides an overview of the habitat and hydraulic models proposed as part
of the evaluation of Project-related effects including boundary conditions transects, 2-D
modeling, single transect PHABSIM (1-D), stranding and trapping, and fish
passage/connectivity.
7.2.2.1. Boundary Condition Transects
The upstream and downstream boundaries as well as the lateral extent of the Focus Areas have
been chosen so that appropriate boundary conditions can be established for the hydraulic and bed
evolution modeling. Considerations include encompassing potential inflow and outflow points
to preserve the mass balance and minimize difficulties and assumptions associated with inflow
points. Potential upstream connections for side channels, side sloughs, and upland sloughs were
also identified and included in the modeling domain. The upstream and downstream limits on
the main channel were identified to either provide relatively uniform flow conditions or
sufficient distance upstream and downstream from areas of interest so that flow conditions in the
area of interest are not significantly affected by the flow directions at the boundary.
Water levels measured during the cross-section and bathymetric surveys for each boundary
condition transect will be used to assist in calibrating the 2-D models for each Focus Area. In
addition to water surface elevations, the depths and velocities measured at the boundary transects
will be used to assist with hydraulic modeling for the single transect PHABSIM sites.
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7.2.2.2. 2-D Modeling
Determining the relationship between river flow and the physical and hydraulic characteristics of
a river system as dynamic as the Susitna River is a complex undertaking that requires
considerable investigation and coordination. This is especially true for assessing project-related
impacts to small, local-scale channel areas containing unique morphology and habitat features
(e.g., fish spawning, groundwater upwelling, stranding and trapping, fish passage/connectivity).
To assist with this effort, 2-D hydraulic modeling will be used to evaluate the detailed hydraulic
characteristics of the Susitna River within the Focus Areas where it is necessary to consider the
more complex flow patterns to understand and quantify project effects under various Project
operation scenarios. The 2-D model will be applied to specific Focus Areas that are
representative of important habitat conditions and the various channel classification types. These
sites will be chosen in coordination with the TWG. A detailed discussion of the 2-D modeling is
presented in RSP Section 6.6.
Selection of the appropriate mesh size for the 2-D bed evolution mode is dictated by several
factors including the size and complexity of the site feature(s); the desired resolution of output
information such as water surface elevation, velocity, depth, and bed material gradation; and any
limitations on the maximum number of elements that the model can simulate. The 2-D models
being considered for this study are formulated with a flexible mesh, allowing the size of the
model element to be varied. Figure 7.2-2 provides examples of a relatively coarse and relatively
fine mesh applied to the potential Focus Area at Whiskers Slough in the Middle River Segment.
Examples of areas that may require finer mesh sizes include sloughs, smaller side channels,
spawning areas, stranding and trapping areas, hydraulic control features, and tributary mouths.
Areas where lower spatial resolution may be appropriate include main channel, floodplains, and
large side channels. In the areas of higher resolution, the mesh size will be on the order of
several feet to 25 feet. In areas where lower spatial resolution is appropriate, the mesh size may
be in the range of 25 to 100 feet (RSP 6.6.4).
At some Focus Areas, two model meshes may need to be developed. One mesh would be for
executing the bed evolution model, which requires orders of magnitude more time to execute
than the 2-D model without the moveable bed options running. The other mesh would be
associated with a fixed bed representation of the site that would be used to output the hydraulic
conditions at a finer resolution for development of aquatic habitat indices. The 2-D
hydrodynamic models will be linked with PHABSIM habitat models and appropriate HSC
criteria to enable development of habitat-flow relationships within Focus Areas.
7.2.2.3. 1-D Modeling Single Transect PHABSIM
Consideration will also be given to the use of 1-D modeling and application and development of
a single transect PHABSIM model. The PHABSIM model (Milhous et al. 1981) will likely be
applied to some of the open-water flow routing model transects to develop relationships between
main channel flow and habitat for the spawning and rearing life stages of the target fish species.
Supplemental main channel transects will be established as needed to more fully characterize
main channel habitats, either as part of the Focus Area analysis or at separate locations
associated with specific habitat types. In addition, the single transect 1-D modeling approach
will also be applied to the Lower Segment studies to capture representative habitat types.
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7.2.2.4. Breaching Flows
The breaching or topping of off-channel habitat features by main channel river flows not only
affects the quantity of water within these features but water quality (turbidity and temperature)
and habitat quality as well. During the 1980s study of the Susitna River, researchers reported
that although breaching flows typically increase the availability of juvenile rearing habitat in
small off-channel areas, as mainstem discharge increases the quality of rearing habitat declines
as velocities in nearshore areas increase (Schmidt et al. 1985). A similar finding was reported
for the effect of water turbidity. Although some turbidity did increase off-channel use by
juvenile Chinook salmon, high turbidity resulting from mainstem flows topping reduced juvenile
fish use (Steward et al. 1985). Vining et al. 1985, reported that the winter topping of cold
mainstem river water into off-channel habitats was the most significant factor contributing to
high levels of embryo mortality in habitats used for chum salmon incubation in the Middle River
Segment. Determining the relationship between mainstem river flow and overtopping or
breaching of sensitive off-channel features will allow for the assessment of potential impacts of
proposed winter Project operation scenarios.
7.2.2.5. Weighted Usable Area Habitat Metrics
The methods proposed in the IFS include a combination of approaches depending on habitat
types (e.g., mainstem, side channel, slough, etc.) and the biological importance of those types, as
well as the particular instream flow issue (e.g., connectivity/fish passage into the habitats,
provision of suitable habitat conditions in the habitats, etc.). During the 1980s studies, methods
were designed to focus on both mainstem and off-channel habitats, although mainstem analysis
was generally limited to nearshore areas. PHABSIM-based 1-D models, juvenile salmon rearing
habitat models, fish passage models, and others were employed and will be considered as part of
the IFS plan. As part of the 2013–2014 study efforts, more rigorous approaches and intensive
analyses will be applied to habitats determined as representing especially important habitats for
salmonid production. As noted above, this will include both 1-D and 2-D hydraulic modeling
that will be linked to habitat-based models.
As part of the Geomorphology Modeling Study (see RSP Section 6.6), several 2-D models are
being considered including the Bureau of Reclamation’s SRH2-D, USACE’s Adaptive
Hydraulics ADH, the USGS’s MD_SWMS suite, DHI’s MIKE 21, and the suite of River2D
models (RSP Section 6.6 for a description of various 2-D model attributes and references). The
River2D model is a two-dimensional, depth-averaged finite-element hydrodynamic model
developed at the University of Alberta and is capable of simulating complex, transcritical flow
conditions. River2D also has the capability to assess fish habitat using the PHABSIM Weighted
Usable Area approach (Bovee 1982). Habitat suitability indices are input to the model and
integrated with the hydraulic output to compute a weighted useable area at each node in the
model domain. While evaluation of habitat indices is directly incorporated into the River2D
suite of models, other 2-D models are also complementary to habitat evaluations. Selection of
potential 2-D models for fish and aquatics evaluations will be coordinated with other pertinent
studies and the TWG.
In response to the effect of potential load-following operations, habitat modeling using weighted
usable area indices may need to be developed using both daily and hourly time steps. Evaluating
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the effects of changes in habitat conditions on an hourly basis may require additional habitat-
specific models such as effective habitat and varial zone modeling.
7.2.2.6. Effective Spawning/Incubation Habitat Analyses
Operation of the Susitna-Watana Project has the potential to influence the quantity and quality of
spawning habitat by altering stream flow in the main channel and off-channel areas of the
Susitna River. While changes in physical conditions (i.e., depth, velocity, and substrate) will
determine the suitability of habitat for salmon spawning, the subsequent survival of eggs and
alevins can be influenced by a different suite of flow-related processes. The eggs of Pacific
salmon are laid in nests, or egg pockets, dug by the female in the gravel of the streambed. The
female then covers the egg pockets with several inches of gravel by vigorous body and tail
movements. Eggs within the spawning site (redd) incubate through the winter and depending on
water temperature, hatch in late winter through spring, then remain within the redd as alevin until
emergence. Mortality during the incubation period, which includes the egg and alevin stages, is
generally high and can be caused by scour associated with flood flows or dewatering and
freezing during low flow conditions. The location of redds within the river channel may have a
major influence on redd survival. If redds are constructed toward the center of the channel when
mainstem flows are low, redds may be scoured by winter flood events. If redds are constructed
along the channel margins or in off-channel areas when mainstem flows are high, redds are at
risk of dewatering or freezing when flows drop during the winter incubation season. In the
Susitna River, as elsewhere, upwelling areas provide stable intergravel conditions and warmer
temperatures during the winter incubation period, providing some protection from dewatering or
freezing.
Flow changes can influence the prevalence of groundwater upwelling, which in turn can affect
the rate of survival and development for eggs and alevins. In the Susitna River, Vining et al.
(1985) suggested that upwelling is the single most important feature in maintaining the integrity
of incubation in slough habitat as well as localized areas in side channel habitats. Upwelling and
intergravel flow also play an important role in determining the water quality at redd sites,
particularly with respect to temperature and dissolved oxygen concentrations. Winter increases
in mainstem flow or stage may affect upwelling by:
Decreasing the rate of groundwater upwelling from the adjacent floodplain.
Diluting relatively warm, stable, upwelling habitats when side channels are breached by
mainstem flow.
Changing the rate of intergravel flows associated with hydraulic gradients between main
channel and off-channel habitats.
The risks posed by flow-related processes on salmonid redds and egg/alevin incubation will be
assessed by developing an effective spawning/incubation model that incorporates separate but
integrated analyses for each process. The spawning/incubation model will be based on
identifying potential use of discrete channel areas (cells) by spawning salmonids on an hourly
basis. Use of each cell by spawning fish will be assumed to occur if the minimum water depth is
suitable and velocity and substrate suitability indices are within an acceptable range defined by
HSC/HSI. Species-specific HSC/HSI information used to identify potential use of a cell by
spawning fish will be developed as described in RSP Section 8.5.4.5. If suitable spawning
conditions exist, that cell will then be tracked on an hourly time step from the initiating time step
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through emergence to predict whether eggs and alevin within that cell were subject to interrupted
upwelling, dewatering, scour, freezing, or unsuitable water.
This process will be repeated for each hour of the potential spawning period based on the species
and life stage periodicities. If sufficient site-specific periodicity information is available, each
hour can be weighted depending on whether it occurs during the peak or off-peak of the
spawning period. If hydraulic conditions during the spawning season were considered suitable
for spawning in a particular cell during the initiating time step, and conditions remained suitable
for egg viability every hour through emergence, then the cell area at the initiating time step
would be considered effective spawning/incubation habitat. This process is repeated for each
cell within the habitat unit containing suitable spawning habitat at time step 1, and the entire
process repeated for each time step through the end of incubation. The resulting areas will then
be summed to determine the cumulative total effective spawning/incubation area for the habitat
unit under existing conditions and alternative operational scenario for each hydrologic year under
consideration.
All of the analyses associated with the effective spawning/incubation model will be performed at
each of the Focus Areas with suitable spawning habitat. The results of the effective
spawning/incubation analysis will be a reach-averaged area calculated by weighting the effective
spawning area derived for each Focus Area by the proportion of Focus Area within the
geomorphic reach (RSP Section 8.5.4.7). The results are calculated in terms of weighted area
(similar to PHABSIM results) and do not represent actual area dimensions. The results cannot
be used to calculate numbers of emergent fry but instead provide habitat indicators that will be
used to conduct comparative analyses of alternative operating scenarios under various hydrologic
conditions.
7.2.2.7. Varial Zone Analysis
Fluctuations in flow will cause shallow portions of the river channel to alternate between wet and
dry conditions; this area of alternating wet and dry is referred to as the varial zone (Figure 7.2-3).
Flow reductions along the channel margins can cause stranding and trapping of juvenile fish and
benthic macroinvertebrates within the varial zone. Repeated dewatering of the varial zone can
result in reduced macroinvertebrate and algae density, diversity, and growth (Fisher and LaVoy
1972; Dos Santos et al. 1988).
Analyses of Project effects on the downstream varial zone can be quantified as the frequency,
magnitude, and timing of downramping events exceeding specified downramping rates; the
frequency, number, and timing of downramping events that occur following varying periods of
inundation; and the frequency, timing, and magnitude of potential stranding and trapping of
aquatic organisms.
The proposed load-following operations of the Project will affect hourly flow fluctuations
downstream of the Watana Dam site. Based on analyses of studies of the effects of hydropower
load-following operations in Washington State, it is generally assumed that faster rates of water
surface elevation reduction are correlated to an increased risk of stranding of aquatic organisms
(Hunter 1992). Salmonid fry are particularly susceptible to stranding and the daily and seasonal
timing of downramping events will influence the potential risk to aquatic organisms.
The goal of the downramping analysis will be to quantify the frequency, magnitude, and timing
of downramping rates by downramping event by geomorphic reach downstream of the Watana
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Dam site. The objectives of this analysis will be to quantify reach-averaged downramping
events by rate under existing conditions and under alternative operating scenarios for selected
hydrologic years. Using the results of the mainstem flow routing models, a post-processing
routine will be used to identify those specific hourly time periods when the water surface
elevations are decreasing (i.e., downramping). For those time periods, the hourly reduction in
water surface elevation will then be computed and expressed in units of inches per hour. A
frequency analysis will be conducted on the hourly downramping hours by downramping event
by geomorphic reach. The frequency analysis will determine the number of downramping events
exceeding selected numeric categories. These categories will be selected in collaboration with
the TWG, but for planning purposes, the following categories are proposed:
Greater than 0 but less than 1 inch per hour
Greater than 1 but less than 2 inches per hour
Greater than 2 but less than 4 inches per hour
Greater than 8 inches per hour
Exceeding downramping guidelines developed by Hunter (1992).
The number of events where downramping rates exceed these categories will be tabulated by
month and by annual total under existing conditions and for alternative operating scenarios.
The frequency, number, and timing of downramping events that occur following varying periods
of inundation will be quantified to evaluate the effects of downramping events on organisms
exhibiting a range of colonization rates. This varial zone analysis can be conducted by total
Focus Area or can be conducted by discrete habitat types within a Focus Area (e.g., main
channel, side channel, sloughs) using an hourly time step integrated over a specified period that
considers antecedent fluctuations in water surface elevations.
7.2.2.8. Fish Stranding and Trapping
Though stranding and trapping are related processes, there are differences that require two
separate analyses for the effects. Both analyses develop indices that represent the potential effect
of reductions in water levels during downramping events on fish and other aquatic organisms.
Stranding involves the beaching of fish as the water levels recede and is typically associated with
low gradient shoreline areas or cover conditions that attract fish to areas where dewatering
occurs. Mortality occurs when stranded fish are beached on dewatered portions of the channel
bed. As water levels recede, some fish may become trapped in channel depressions or pools.
Although trapped fish may survive for short periods of time, the potential for mortality increases
based on factors including temperature fluctuations, reduction in dissolved oxygen, predation,
and stranding as the water in the pool infiltrates the substrate.
The approach to the stranding and trapping analyses will be similar to other analyses involving
the evaluation of the effects of water surface elevation fluctuations in the varial zone. Stranding
and trapping indices utilize results of the mainstem flow routing models to determine the water
surface elevations on an hourly basis within Focus Areas. Stage fluctuations are applied within
Focus Areas using the digital terrain models to quantify the frequency, timing, and magnitude of
stranding events under existing conditions and alternative operational scenarios. The results of
the mainstem flow routing models and the digital terrain models are also combined to quantify
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the frequency, timing, and duration of trapping events for discrete channel features within Focus
Areas. The stranding and trapping analyses determine evaluation indices based on each water
level fluctuation cycle.
The stranding and trapping analyses track the period of dewatering (stranding) or the period of
disconnection (trapping). Fish are assumed to return to potential stranding and trapping areas
shortly after the water surface elevation rises to once again inundate/connect the side channel
areas. Stranding and trapping indices are not treated as values that are summed on an hourl y
basis; instead, stranding and trapping are viewed as a series of events, and part of the index
expression includes this frequency of events. Therefore, the results are computed at the end of
an event based on the duration of the event, and then results are summed over the series of
events.
Downramping rates will be determined as part of the stranding analyses including the
exceedance of specific numeric categories ranging from 1 inch per hour to over 8 inches per
hour. For trapping analyses, ramping rates will not be directly incorporated as a factor in the
calculation of the indices. Strong relationships between ramping rate and incidence of trapping
are not consistently demonstrated in previous studies (Hunter 1992; Higgins and Bradford 1996;
R.W. Beck and Associates 1989). The results of both stranding and trapping evaluation
indicators can be quantified under existing conditions and alternative operational scenarios for
selected hydrologic conditions.
The indices for stranding and trapping are based on equations that relate physical characteristics
of the stranding and trapping sites to the potential for stranding and trapping to occur. The
information for the physical site characteristics will be derived from the bathymetry and mapping
through the application of GIS. The index equations have physical factors related to site area,
depth, and cover conditions. The observations and data collected during the stranding and
trapping field surveys will assist in developing the ratings for several of these factors (RSP
Section 8.5.4.5).
For planning purposes, potential stranding areas are defined as areas with a bed slope of 4
percent or less, excluding depression areas that are included in the trapping area analysis.
Stranding areas are also defined as areas with features, such as emergent vegetation found
alongside slough margins, which are observed to contribute to an increased risk of stranding
regardless of bed slope based on the results of site-specific surveys. Specific stranding zones are
defined at elevation intervals to allow for tracking of dewatering of stranding areas as the water
surface elevation rises and falls. Stranding areas are also defined as contiguous areas of 1,000
square feet or greater. The potential presence of fish in a stranding site is assumed to be directly
proportional to the size of the stranding area. RSP Section 8.5.4 presents a detailed description
of the equations and indexes use to calculate the potential for stranding and trapping events.
7.2.2.9. Fish Passage/Off-channel Connectivity
Several environmental variables may affect fish passage and connectivity within sloughs and
side channels and tributary deltas. In general, at a given passage area the water conditions
(primarily depth) interact with conditions of the channel (length and uniformity, substrate size) to
characterize the passage conditions that a particular fish encounters when attempting to migrate
into, within, and out of a slough, side channel, or tributary delta. The likelihood of a particular
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fish successfully navigating through a difficult passage reach will depend on the environmental
conditions as well as the individual capabilities and condition of the fish.
Depth passage in sloughs, upland sloughs, side channels, and at tributary delta mouths will be
assessed following the methods of Sautner et al. (1984) that focus on salmon passage in sloughs
and side channels. Two-dimensional modeling, not available in the 1980s, will also be applied.
Although salmon passage remains a key concern, the passage methods are generally applicable
to other species where depth passage criteria are known or can be developed. The main goal of
the fish passage and off-channel connectivity is to evaluate the potential creation of fish passage
barriers within existing habitats (tributaries, sloughs, side channels, off-channel habitats) related
to future flow conditions and water surface elevations. Further details concerning the fish barrier
and passage analysis are presented in RSP 9.12.
7.2.3. Temporal and Spatial Habitat Analyses
The IFS will result in the collection of data and development of different types of habitat-flow
relationships from spatially distinct locations within each of the Focus Areas, and from selected
cross-sectional transects outside of the Focus Areas that contain a variety of habitat types. Types
of relationships will include but not be limited to those founded on PHABSIM that depict WUA
or habitat versus flow by species and life stage; effective habitat versus discharge relationships
that define how spawning and incubation areas respond to flow changes; varial zone analysis that
quantifies areas of stranding and trapping relative to flow change; and groundwater-surface water
flow relationships relative to upwelling and spawning habitats. Additional components that will
factor into the habitat – flow relationships will include those associated with breaching flows,
upwelling, water temperature, and turbidity. These relationships will be part of the analytical
framework and conceptual models that will be used in evaluating the operational effects of the
Project (RSP Section 8.5.4.8) on different habitats. This will require both a temporal analysis
that focuses on how the various habitat response variables change with flow over biologically
important time periods (i.e., periodicity), and a spatial analysis that can be used not only for
evaluating specific relationships on a site/transect specific or Focus Area basis, but also for
expanding or extrapolating results from measured to unmeasured habitats within the river. This
latter analysis is needed in order to assess system-wide Project effects.
7.2.3.1. Temporal Analysis
Temporal analysis will involve the integration of hydrology, Project operations, the Mainstem
Open-water Flow Routing Model, and the various habitat-flow response models to project
spatially explicit habitat changes over time. Several analytical tools will be utilized for
evaluating Project effects on a temporal basis. This will include development and completion of
habitat-time series that represent habitat amounts resulting from flow conditions occurring over
different time steps (e.g., daily, weekly, monthly), as well as separate analysis that address
effects of rapidly changing flows (e.g., hourly) on habitat availability and suitability.
The Mainstem Open-water Flow Routing Model and habitat models will be used to process
output from the Project operations model. This will be done for different operating scenarios,
hydrologic time periods (e.g., ice free periods: spring, summer, fall; ice-covered period: winter
[will rely on Ice Processes Model – Section 7.6]), Water Year types (wet, dry, normal), and
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biologically sensitive periods (e.g., migration, spawning, incubation, rearing) and will allow for
the quantification of Project operation effects on the following:
Habitat areas (for each habitat type – main channel, side channel, slough, etc.) by species
and life stage; this will also allow for an evaluation of the effects of breaching flows on
these respective habitat areas and biologically sensitive periods (e.g., breaching flows in
side channels during egg incubation period resulting in temperature change).
Varial zone area (i.e., the area that may become periodically dewatered due to Project
operations, subjecting fish to potential stranding and trapping and resulting in reduced
potential invertebrate production).
Effective spawning areas for fish species of interest (i.e., spawning sites that remain
wetted through egg incubation and hatching).
Other riverine processes that will be the focus of the Geomorphology (see Sections 6.5
and 6.6), Water Quality Modeling (see Section 5.6), and Ice Processes (see Section 7.6)
studies including mobilization and transport of sediments, channel form and function,
water temperature regime, and ice formation and decay timing. The IFS studies will be
closely linked with these studies and will incorporate various model outputs in providing
a comprehensive evaluation of instream flow-related effects on fish and aquatic biota and
habitats.
As an example, using the habitat versus flow relationships (based on HSC and HSI metrics
described in RSP Sections 8.5.4.5.1.1 and 8.5.4.5.1.2) developed within the different Focus
Areas and at selected cross-sections, an evaluation of habitat change over time can be completed
using habitat time series analysis. The basic premise of a habitat time series analysis is that the
physical habitat in a stream at any given time can be calculated from the stream flow using the
equation:
HA(t) = WUA{Q(t)}
where WUA = physical habitat versus flow relationship for a given species and life
stage;
Q(t) = stream flow at time t; and
HA(t) = habitat area for time t.
The results of the time series analysis will be compared under baseline (unregulated) conditions
with one or more Project Operational Scenarios. This type of analysis will be done for each
biologically relevant period (e.g., adult migration and holding, spawning, incubation, juvenile
rearing, and others) for a given species and life stage, and for different Water Year types (e.g.,
wet, normal, dry). Consideration will also be given to identifying year types that reflect cold,
normal, and above average air temperatures. The analysis will include development of habitat-
duration curves that depict habitat exceedances based on the hydrologic record.
7.2.3.2. Spatial Analysis
How the data and habitat-flow relationships collected and developed from one location relate to
other unmeasured locations is the focus of the spatial analysis. This analysis is crucial to
providing an overall understanding of how Project operations may affect habitats and riverine
processes on a system-wide basis and will feed directly into the Integrated Resource Analysis
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(RSP Section 8.5.4.8). This analysis will be completed in 2014 after all data are collected and
respective models have been developed. Just like the temporal analysis, the final procedure(s)
for completing spatial analysis will be developed collaboratively with the TWG and with input
from other resource disciplines.
Completion of spatial analyses of the Susitna River will be challenging given its length, widely
variable size (width), diverse geomorphologies, and complex habitat types. This variability is
readily apparent in the Middle River Segment and becomes even more pronounced in the Lower
River Segment with the addition of flow from the Talkeetna and Chulitna rivers and resulting
expanded floodplain. This will require the development of an approach that considers the
distinctiveness of the different habitat types within a given area and at the same time the
similarity of these habitat types to other areas. Development of habitat – flow relationships for
specific habitat types (e.g., side channel, side slough) and mesohabitat types (riffle, run, pool,
etc.) from one area should then, with appropriate adjustment for dimensional differences and
other distinguishing factors, be expandable to unmeasured areas containing similar
characteristics.
A substantial effort was already advanced toward development of a spatial habitat analysis
approach as part of the 1980s studies (Aaserude et al. 1985; Klinger-Kingsley et al. 1985;
Steward et al. 1985) (see Section 7.1.6). Inspection of those studies indicates that although the
tools and computational techniques that were applied may be outdated, the general principles and
precepts that served to guide development of the approach remain sound today. As a result, they
provide a good starting point from which to build a more contemporary approach founded on
new sampling technologies and more sophisticated models that will provide for a more robust
spatial analysis, including procedures for extrapolation of habitat-flow relationships from
measured to unmeasured areas.
Importantly, the 1980s studies made a clear distinction regarding extrapolation approaches that
are suited for single thread channel versus those for multi-thread channels. Aaserude et al.
(1985) correctly noted that for single thread channels, it is appropriate and is routinely done
today to utilize extrapolation procedures that are based on proportional lengths of mesohabitat
types that are identified as part of a habitat mapping exercise. This approach was originally
fostered by Morhardt et al. (1983) and has remained in use since. Indeed, this approach, or some
modification thereof, will be utilized for extrapolating PHABSIM-based habitat–flow
relationships derived from main channel mesohabitat specific transects (e.g., riffle, run, pool,
etc.) as identified from the Characterization of Aquatic Habitats Study (RSP Section 9.9) to
unmeasured mesohabitats within a given geomorphic reach. This will be done in a series of
steps that include the following:
Completion of habitat mapping (see Section 9.9) that will delineate main channel
mesohabitats into categories of cascades, riffle, pool, run, and glide as described in
Section 8.5.4.2.1.1.
Determination of percentages of each mesohabitat type within each geomorphic reach.
Assignment of existing transects (those already established as input to the open-water
flow routing model (RSP Section 8.5.4.3) and new main channel transects established
either as part of the detailed Focus Area studies (RSP Section 8.5.4.6.1.2) or added to
capture a specific main channel habitat not represented by the existing transects to a
specific mesohabitat category.
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Weigh each of the transects within a given geomorphic reach based on the percentages of
mesohabitats represented in the reach (e.g., in a reach that is 30 percent riffle with 6 riffle
transects; each transect would be assigned a weighting factor of 5 percent (30 percent/6)
of the total reach length).
Apply additional transect weighting based on location to account for tributary and
accretion flow.
Derive habitat-flow relationships (by species and life stage) for a given geomorphic reach
based on transect specific habitat-flow relationships by mesohabitat type weighted by the
percentages of the reach (based on lineal distance) containing each mesohabitat type (as
determined from habitat mapping).
This latter step will then result in a composited habitat-flow relationship that considers all
mesohabitat types within a given geomorphic reach. Further compositing of relationships for all
geomorphic reaches (with consideration for flow accretion, etc.) will allow for the derivation of
habitat-flow relationships (by species and life stage) for the entire segment of the main channel
Susitna River. Coupled with the open-water flow routing model, these relationships can then be
used to evaluate how main channel habitats may vary under different operational scenarios and
will provide one of the tools necessary for completing the spatial analysis.
A different approach will be needed for multi-thread channels because they contain multiple
habitat types (e.g., side channel, side slough, upland slough, etc.) within which each may contain
multiple mesohabitat types (e.g., riffle, run, pool, etc.). In addition, flows within some of the
habitat types may be governed by groundwater-surface water interactions that cannot be modeled
directly by PHABSIM. The framework for evaluating multi-channel habitats described in
Aaserude et al. (1985) provides a logical construct for achieving this and as noted above, is the
starting point for the current Instream Flow Study. Unlike the approach for a single thread
channel where a reasonable assumption is that habitat-flow response relationships will generally
be similar among mesohabitat types, the diversity of habitats within a multi-thread channel
means that habitat-flow responses are dynamic and highly variable. In addition, multi-thread
channels are spatially discontinuous and disconnected so that it is not possible to extrapolate
entire multi-channel units to others. As noted by Aaserude et al. (1985), the braided river
environment is too dynamic and variable for the development of quantitative relationships
between discharge and physical habitat variables such as depth, velocity, and channel structure
on a river corridor-wide basis for use in extrapolation. Instead, an approach for evaluating
habitat is needed that focuses on portions of the river corridor but then relates the findings of
those portions to other areas of similar character.
The method presented by Aaserude et al. (1985) was based on the provision of two separate
databases, the first containing habitat-flow response relationships for the full range of habitat and
mesohabitat types found within selected portions of the river, the second an expansive database
consisting of aerial imagery and targeted measurements of a select number of habitat response
variables from essentially all of the habitat types found within the primary multi-threaded
channels in the Middle River Segment. Input to the first database was provided largely by a
number of site-specific studies that included application of PHABSIM (IFG), DIHAB, and
RJHAB models to define habitat-flow response relationships in different habitat types, as well as
surveys to determine breaching flows. However, the “one size fits all” concept that may be valid
for expansion of mesohabitat types does not apply to the multi-thread network of channels in the
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Susitna River. Consequently, further stratification of the habitat types (side channel, side slough,
upland slough, etc.) was needed and resulted in the designation of 10 “representative groups”
that provided a sub-level of categorization to the habitat types (Steward et al. 1985; Aaserude et
al. 1985). These 10 groups consisted of “identifiable combinations of flow – related attributes”
(Steward et al. 1985) that were deemed readily distinguishable and included the following:
Group I – Predominantly upland sloughs. Areas are highly stable due to persistence of
non-breached conditions. Area hydraulics characterized by pooled clear water with
velocities frequently near 0 fps and depths > 1 ft. Pools commonly connected by short
riffles with velocities < 1 fps and depths < 0.5 ft.
Group II – Side sloughs that are characterized by relatively high breaching flows
(>19,500 cfs), clear water caused by upwelling groundwater and large channel length to
width ratios (> 15:1).
Group III – Areas with intermediate breaching flows and relatively broad channel
sections. These areas consist of side channels which transform into side sloughs at
mainstem discharges ranging from 8,200 to 16,000 cfs. These areas are distinguishable
from Group II by lower breaching flows and smaller length to width ratios. Upwelling
water is present.
Group IV – Side channels that are breached at low flows and possess intermediate mean
velocities (2–5 fps) at a mainstem discharge of approximately 10,000 cfs.
Group V – Mainstem and side shoal areas that transform to clear water side sloughs as
mainstem flows recede. Transformations generally occur at moderate to high breaching
flows.
Group VI – Similar to Group V. Sites within this group are primarily overflow channels
that parallel the adjacent mainstem, usually separated by sparsely vegetated gravel bar.
Upwelling may or may not be present. Habitat transformations within this group are
variable in type and timing.
Group VII – Side channels that breach at variable yet fairly low mainstem discharges and
exhibit characteristic riffle/pool sequence. Pools are frequently large backwater areas
near the mouth of the sites.
Group VIII – Area that dewater at relatively high flows. Flow direction at the head of the
channels tends to deviate sharply (> 30 degrees) from the adjacent mainstem.
Group IX – Secondary mainstem channels that are similar to the primary mainstem
channels in habitat character, but distinguished as being smaller and conveying a lesser
proportion of the total discharge. Areas within this group have low breaching discharges
and are frequently similar in size to large side channels, but have characteristic mainstem
features, such as relatively swift velocities (> 5fps) and coarser substrate.
Group X – Large mainstem shoals and margins of mainstem channels that show signs of
upwelling.
Another element of the method described by Aaserude et al. (1985) that was used as part of the
representative group designation was its consideration of habitat transformation wherein
mainstem areas may functionally transition from side channels to side sloughs and ultimately
become dewatered as flows recede. A total of 11 habitat transformation categories were defined
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and considered when comparing flow conditions; these included comparative categories of clear
vs. turbid water, upwelling present vs. absent, and distinct vs. indistinct side channel formation.
Model development from which to base habitat-flow response relationships within each of the
groups relied upon the site-specific models applied at different study areas. In addition to
traditional metrics of weighted usable area (WUA), a number of other metrics were derived that
included Wetted Surface Area (WSA), Gross Habitat Area (GHA), a Habitat Availability Index
(HAI), a Habitat Distribution Index (HDI), and a Habitat Quality Index (HQI). These
relationships were then applied to un-modeled areas assigned to different “representative groups”
taking into account two important distinguishing characteristics—structural habitat quality and
breaching flow. Structural habitat quality was evaluated for each site based on field data that
considered cover type, percent cover, dominant substrate size, substrate embeddedness, channel
geometry, and riparian vegetation. From this, a Structural Habitat Index (SHI) was computed for
each un-modeled area. Breaching flows were likewise determined for each unmeasured area.
These two elements were then used as adjustment factors for defining the derived non-modeled
habitat – flow response relationship. Once relationships were derived from un-modeled areas, it
was then possible to integrate results into an overall assessment of habitat-flow responses within
each representative group; these were presented in Steward et al. (1985). The next step in the
process would have been to conduct a system-wide (at least for the Middle River Segment)
evaluation of habitat-flow responses that would have aggregated the responses into a system-
wide habitat-flow response relationship. However, this step was never completed as part of the
1980s studies.
7.2.4. Instream Flow Study Integration
As described in Section 2, construction and operation of the proposed Project will change
downstream flow conditions on an hourly, daily, and seasonal basis. Load-following operations
will increase the frequency, timing, and magnitude of hourly and daily flow fluctuations, and
increased flow releases during winter months will be followed by decreased flow releases as the
reservoir refills. The effects of such flow changes will vary depending on the operational rules
guiding power generation. The suite of Project operational rules governing hourly, daily, and
seasonal dam releases are termed operational scenarios. Scenarios developed to benefit one
specific resource may have a detrimental effect on another resource. For instance, maintaining
high flow releases during the spring salmon smolt out-migration period may delay reservoir refill
and could affect Project releases for late summer coho rearing. An operational scenario designed
to benefit one resource, such as cottonwood germination, may have an unintended detrimental
effect on another resource. Constraints on Project flow releases to benefit one natural resource
may affect the ability of AEA to meet its energy needs. Identifying an operational scenario that
satisfies the interests of all parties requires an evaluation of multiple resource benefits and risks.
Tools to inform the evaluation of flow scenarios have been developed in support of other water
control decisions. A Decision Support System (DSS) was developed to support the evaluation of
alternative flow regimes on resources of the Black Canyon of the Gunnison National Park (Auble
et al. 2009). The DSS developed by Auble was intended to provide decision-makers with the
tools to manage large data sets of simulated flow alternatives and evaluate the relative
desirability of those alternatives with respect to natural resources. The intent was not to evaluate
alternatives, but to provide a tool for informing the evaluation of alternatives. The basic
approach was to array differences among alternative flow regimes by calculating values of
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indicator variables representing different habitat characteristics or processes of the riverine
ecosystem. Auble noted that the scientific understanding and quantitative relations between flow
and the physical and biological responses of riverine systems are complex and may be
imperfectly represented by the indicators. Disagreement about the relative importance or
weighting of multiple resource concerns can delay or derail the decision-making process.
Ideally, a DSS requires a balance between simplification of assumptions to reduce complexity
and oversimplification that does not reflect the constituent variables and calculations. Auble
produced a set of indicators grouped into several areas of natural resources concerns. The
indicators were replicable calculations that reflected conditions or processes within each area of
concern. Alternatives were compared directly in terms of these indicators, each of which could
be individually understood and challenged in terms of the assumptions involved in the
calculations. Different users could make different decisions using this system because they
might weight the importance of multiple indicators differently or value different aspects of the
system. Thus, the goal of the DSS was not to make a decision, but rather to reduce the
complexity of information and focus attention on trade-offs involved in the decision.
The Yakima River DSS (Bovee et al. 2008) was designed to quantify and display the
consequences of alternative water management scenarios to provide water releases for fish,
agriculture, and municipal water supply. Output of the Yakima River DSS consisted of a series
of conditionally formatted scoring tables that compiled changes in evaluation indicators.
Increases in the values of selected indicators were reflected in a color-coded scoring matrix to
provide decision-makers with a quick visual assessment of the overall results of an operating
scenario. The scoring matrix required that evaluation indicators used to describe resources be
rated as comparative values. A variety of weighting strategies were provided during the
decision-making process to reflect the relative importance of different indicators.
In support of relicensing decisions for the Baker River Hydroelectric Project, FERC No. 2150, a
DSS-style matrix was developed to evaluate multiple resource concerns under alternative
operational scenarios (Hilgert et al. 2008). The focus of the operations and aquatic habitat
analyses was to identify a mode of operation that would protect aquatic resources while meeting
multiple licensing participant interests. Aquatic habitat analyses were run concurrent with
analyses of economic, flood control, and other resources. Various licensing participants
championed different approaches to the relationships between minimum and maximum flow
releases, minimum and maximum reservoir pool levels, and downramping rates. Through study
and analysis, some scenarios were proven infeasible and abandoned, others were modified, and
others were dissected and recombined with other approaches. Alternative operational scenarios
were evaluated using a matrix that presented indicators of resource concerns without applying
comparative weighting factors. Collaboration among licensing participants gradually led to
consensus on a preferred flow management plan that contributed led to a Settlement Agreement.
Evaluation of Project effects on Susitna River resources will require inventive modeling
approaches that integrate aquatic habitat modeling with evaluation of riverine processes such as
groundwater-surface water interactions, water quality, and ice processes. The number of
reaches, habitat types, target species and life stages, and resource-specific models will result in
large data sets for multiple resources that will be difficult to comprehend when evaluating
alternative operational scenarios. A DSS-type process will be needed to evaluate the benefit and
potential impacts of alternative operational scenarios. For illustration purposes, an example
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matrix was developed (Table 7.2-2) to display a range of potential indicator variables including
the following:
Power
Hydrologic
Reservoir
Ramping rates
Stranding and trapping
Salmon spawning and incubation
Salmon rearing
Other fish species
Riparian
Recreation
Other aquatic conditions
As habitat-specific models are developed, they will be used to evaluate existing conditions and
the effects of alternative operational scenarios for multiple resources and riverine processes. A
Project operations model will be used to simulate Project inflow, outflow, power generation, and
reservoir pool levels for alternative operational scenarios under a range of hydrologic years. The
operations model will be used to quantify revenue from power generation based on operational
constraints selected for each alternative scenario. Types of constraints may include maximum
and minimum instream flow releases, ramping rates, and reservoir levels. These constraints may
be varied within a hydrologic year according to schedules specified for each alternative.
Operations model output may include simulated reservoir elevations, turbine, spill, and total
outflow, as well as hourly stream flow immediately below the powerhouse. Output from the
operations model will be used as input for the downstream habitat models. Hourly flows
immediately below the powerhouse will be routed downstream using the mainstem open-water
flow routing models (see RSP Section 8.5.4.3) and Ice Processes Model (see RSP 7.6).
Each habitat and riverine processes model can be used to develop large data sets of hourly
habitat conditions. The DSS-type process will be used to focus attention on those attributes that
the TWG believes are highest priority in evaluating the relative desirability of alternative
scenarios with respect to natural resources. Evaluation indicators selected for a DSS-type matrix
represent a preliminary analysis to identify the most promising scenarios. When discussion of
alternatives focuses on only a few remaining scenarios, those final scenarios will be evaluated
using the larger data set of habitat indicators to ensure that environmental effects are consistent
with the initial analyses.
The selection of indicator variables will be developed in collaboration with the TWG. For
planning purposes, it is assumed that values for each evaluation indicator will be developed and
presented for a range of alternative operational scenarios without rating or comparative
weighting of various resources. Although incorporating a relative weighting system similar to
the Yakima River DSS (Bovee et al. 2008) would simplify the evaluation process, reaching
consensus on weighting factors may divert attention from understanding and discussing the
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merits of constituent variables. Table 7.2-2 represents one option to present Project decision-
makers with information on the effects of alternative operational scenarios on resource values.
Development of a DSS-type process, and supporting software to efficiently process data
analyses, will be initiated in collaboration with the TWG after the initial results of the various
habitat modeling efforts are available in 2014. The intent is to prepare the DSS-type evaluation
process by early 2015 to assist scenario evaluations in support of the License Application.
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8. TECHNICAL MEMORANDUM – BIOLOGICALLY RELEVANT
PHYSICAL PROCESSES IN THE SUSITNA RIVER
From a riverine ecosystem perspective, the flow regime of a given system serves not only to
create and maintain the structure of the habitat (i.e., channel morphology) that is defined by the
interaction of flow with the local geology, but also the associated physical processes that can
express themselves in biologically meaningful ways. Understanding those processes and their
linkage to flow regime is an integral component when considering instream flows for fish,
aquatics, and riparian natural resources, especially when considering the effects of flow
regulation. Importantly, such physical processes can go beyond those typically defined at the
microhabitat level such as the parameters of depth, velocity and substrate that are part of the
elements comprising HSC.
This TM serves to describe the processes that were identified in the Susitna River during the
1980s Su-Hydro studies that were considered biologically relevant, and how those processes may
be influenced by flow regulation. This is followed by a brief discussion of how the 2013-2014
studies will be addressing these processes.
8.1. Su-Hydro 1980s Studies
A number of biologically relevant physical processes were identified during the early 1980s Su-
Hydro studies of the Susitna River including groundwater, turbidity, water clarity, ice, and
substrate composition. These processes were investigated primarily as part of biological studies
to determine their influence on fish distribution and abundance and salmon egg incubation and
survival. Investigators concluded relatively early-on that these factors in addition to, or in
combination with, discharge were important components to fish and aquatic habitat and could be
affected by the proposed hydroelectric development (Trihey 1982, Estes and Bingham 1982).
During later phases, the studies became more focused on acquiring specific information that
could be used in the development of instream flow models (see Section 7). Those studies
included investigations of species and lifestage specific HSI models that considered turbidity,
water clarity, and the presence of groundwater upwelling (see Section 7, Habitat Utilization and
Habitat Suitability Curve Development Studies).
8.1.1. Groundwater Upwelling
During the winter of 1981-1982 Trihey (1982) investigated water temperatures at 13 sites in the
Middle River Segment between RM 125 and RM 143 and compared surface water to intergravel
measurements. These sites were selected because they had observations of salmon spawning
earlier in 1981 and they were the first sites evaluated that suggested the importance of
groundwater upwelling to fish species in the Susitna River. Measurements of surface and
intergravel water temperature at these sites revealed that intergravel temperatures were higher
and more stable than surface water temperatures (e.g., Figure 8.1-1). Trihey (1982) offered the
following three hypotheses developed from his observations:
1. Mid-winter water temperatures in the sloughs are independent of mainstem water
temperatures.
2. River stage appears to be influencing groundwater upwelling in the sloughs.
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3. Spawning success at upwelling areas in side channels appears to be limited by
availability of suitable substrate (streambed materials).
Flow changes can influence the prevalence of groundwater upwelling, which in turn can affect
the rate of survival and development for eggs and alevins. In the Susitna River, Vining et al.
(1985) suggested that upwelling is the single most important feature in maintaining the integrity
of incubation in slough habitat as well as localized areas in side channel habitats. Upwelling and
intergravel flow also play an important role in determining the water quality at redd sites,
particularly with respect to temperature and dissolved oxygen concentrations. Thus, increases in
winter discharge and stage that may result from the operation of a hydroelectric project may
affect upwelling by:
Decreasing the rate of groundwater upwelling from the adjacent floodplain.
Diluting relatively warm, stable, upwelling habitats when side channels are breached by
mainstem flow.
Changing the rate of intergravel flows associated with hydraulic gradients between main
channel and off-channel habitats.
In addition to the importance to incubating salmon eggs, groundwater inflows to sloughs were
also considered potentially important as overwintering habitat (Dugan et al. 1984). Groundwater
upwelling locations were mapped at a number of survey locations in the Middle and Lower River
as part of the Su-Hydro Aquatics Studies. Estes and Schmidt (1983, Appendix F) reported the
location of approximately 90 upwelling sites in the Middle River (Figure 8.1-2). Examples of
upwelling locations at Slough 8A and Slough 21, which were sampled as DFH sites during 1982
and sampled during winter studies by Hoffman et al. (1983), are provided in Figures 8.1-2 to 8.1-
4.
Intensive winter studies were implemented in March 1983 (Hoffman et al. (1983) and 1984-1985
(Vining et al. 1985; described in the previous section). Hoffman et al. (1983) reported on surface
and intergravel water temperature monitoring at seven sites during the winter of 1982 to 1983
and also conducted incubation and emergences studies. In addition to water temperature,
Hoffman et al. (1983) also monitored dissolved oxygen, pH, and specific conductance levels and
noted the importance of dissolved oxygen exchange as a factor affecting egg incubation.
Continuous surface and intergravel monitoring sites were established at six sloughs (Sloughs 21,
19, 16B, 11, 9, and 8A) and the mainstem at LRX 29 and Gold Creek. Measurements were
collected from late August 1982 through early June 1983. Sites were chosen because they were
known chum salmon and/or sockeye salmon spawning locations.
Incubation and emergence studies were conducted at seven sites during the winter of 1982-83
(Sloughs 21, 20, 11, 9 and 8A) and two side channels (A and B located at RM 136.2 and 137.3,
respectively; Hoffman et al. 1983). Standpipes located along each bank of the selected sloughs
were used to measure intergravel water temperature and chemistry (10 per bank, 20 total per
location). Sampling at these locations occurred during April 15 to 18 and April 29 to May 2.
Eggs were sampled once per month from September 1982 through May 1983 using a high
pressure water jet to dislodge eggs into a mesh sack.
The 1982-1983 winter study (Hoffman et al. 1983) and 1984-1985 study (Vining et al. 1985)
confirmed patterns of surface- and ground-water temperature observed by Trihey (1982).
Intergravel water temperatures in slough habitats tend to be relatively stable (Hoffman et al.
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1983). Vining et al. (1985) observed similar patterns for sloughs and side channels where
upwelling was present. At tributary and mainstem sites Vining et al. (1985) observed that
intergravel temperatures were variable and approach 0°C in October, which indicated intergravel
waters were originating from surface waters. The continuous monitoring stations demonstrated
intergravel water temperatures in areas with upwelling were warmer than surface waters during
the ice covered period. As the spring thaw begins (about mid-April in 1983), intergravel
temperatures then become cooler than surface water temperatures.
Monitoring during three days in mid-April and four days in late-April,1983, at sites with
standpipes placed along slough banks indicated substantial variability in upwelling water
temperatures with no consistent relationship between right bank and left bank standpipes at a site
(Hoffman et al. 1983). Average intergravel temperatures were cooler than surface waters, which
was consistent to the patterns observed from continuous monitoring.
Mean intergravel dissolved oxygen measurements ranged from 4.6 mg/L at Slough 8A during
both sampling periods to 8.5 mg/L at Slough 11 during the first sampling period of 1983
(Hoffman et al. 1983). Intergravel dissolved oxygen was substantially lower than surface water
dissolved oxygen that ranged from a mean of 9.1 mg/L at Slough 21 during the first sampling
period to 11.2 mg/L at Slough 8A during the second sampling period. Measurements of pH were
found to be within suitable levels for both intergravel and surface water. Significant differences
and a significant interaction were found for specific conductance between sites and between left
and right banks within the sites. Hoffman et al. (1983) concluded that multiple water sources
were the cause of these differences. Vining et al. (1985) observed similar patterns for dissolved
oxygen and pH. For specific conductance, Vining et al. (1985) observed similar patterns in
sloughs; however, specific conductance was lower in tributary sites, which were not studied by
Hoffman et al. (1983), than slough and mainstem sites.
Bigler and Levesque (1985) monitored surface and intergravel water temperature, egg
development, outmigration, and substrate composition at three Lower River side channels where
relatively high levels of chum salmon spawning was documented. The three sites included the
Trapper Creek side channel (RM 91.6), Sunset Side Channel (RM 86.9), and Circular Side
Channel (RM 75.3). Chum salmon surveys and instream flow modeling were also conducted at
these sites. Egg development was also monitored at the Birch Creek Camp Mainstem (RM 88.6)
site and a fyke net deployed for two days in early May 1984.
Similar to Hoffman et al. (1983), Bigler and Levesque (1985) observed that most of these chum
salmon spawning areas had upwelling and intergravel temperatures were higher than surface
water temperatures. In general, eggs developed through the alevin and emergence stage at all
sites. The upper portion of the Sunset Side Channel did not have groundwater upwelling and
eggs laid in this portion of the study site froze.
As described above, substantial effort was expended to understand groundwater effects (i.e.,
temperature and dissolved oxygen) that are important to salmon egg incubation rates and
survival. The results of these studies led to the development of alternative HSC curves for chum
and pink salmon spawning that could be used in the instream flow models (see Section 7, Habitat
Utilization and Habitat Suitability Curve Development Studies).
Determining overwintering locations and habitat conditions for juvenile salmon and resident fish
species was difficult during the 1980s because fish captures in general decline in the winter
period. In addition, because of logistical and safety considerations relatively few sites could be
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sampled in the winter and those were infrequently sampled. Nevertheless, studies concluded that
upwelling in sloughs was an important factor contributing to favorable overwintering habitat for
Chinook and to a lesser extent coho salmon (Roth and Stratton 1985, Stratton 1986). Roth and
Stratton (1985) reported that young of the year Chinook salmon became more concentrated in
upwelling areas of sloughs as temperatures declined during late September and early October.
8.1.2. Turbid and Clear Water Zones
Typical of glacial fed streams and rivers, the Susitna River is extremely turbid during most of the
year (Harza-Ebasco 1985). Turbidity, as measured in nephelometric turbidity units (NTUs) is a
metric of light penetration which is an important factor affecting primary productivity. Turbidity
in the Susitna River was primarily determined by levels of inorganic glacial flour suspended in
the water. Glacial water from the Chulitna River, with turbidity measured as high as 1,920 NTU,
is a major contributor of turbidity to the mainstem Susitna River. The maximum turbidity level
measured in the Talkeetna River during 1982 was 272 NTU. Turbidity is affected by the amount
of glacial melt and precipitation in the form of rain. Consequently, turbidity tends to be high in
the summer and low in the winter (Harza-Ebasco 1985; Figure 8.1-5). Turbidity levels tended to
decline in a downstream direction below the Three Rivers Confluence. Maximum turbidity
measurements at Sunshine and Susitna stations were 1,056 and 790 NTU, respectively.
Turbidity in side channels and side sloughs was affected by inflows from clear water tributaries
and groundwater (Harza-Ebasco 1985). In addition, breaching at the heads of side sloughs or
side channels allowed turbid mainstem water to flow through. When flows were below
breaching levels, turbidity was substantially lower and less variable (Figure 8.1-6).
While turbidity information was collected at fish sampling sites during 1981, the study design for
1982 explicitly considered turbid mainstem water, clear water from tributaries or groundwater,
and mixing zones, as well as water velocity and how the mainstem river stage influenced
conditions. During 1982, 17 sites referred to as Designated Fish Habitat (DFH) sites were
surveyed twice monthly from June through September during the open water season (Estes and
Schmidt 1983). Twelve sites were located in the Middle River (Whiskers Creek and Slough to
Portage Creek Mouth) and five were located in the Lower River (Goose Creek and Side Channel
to Birch Creek and Slough; Tables 4.2-1 and 4.2-2).
Habitat zones were delineated within each DFH site based upon the influence of mainstem flow,
tributary flow, and water velocity (Table 8.1-1; Figure 8.1-7). Because the zones were based
upon flow characteristics, the size of the zones may have varied from survey to survey. As part
of the statistical analysis the nine zones were aggregated into Hydraulic and Water Source Zones
(Table 8.1-2). In addition to statistical tests to determine associations between fish species catch
per unit effort and aggregate hydraulic and water source zones, tests were also run to examine
correlations between catch per unit effort and habitat variables including water temperature,
turbidity, and velocity (Schmidt and Bingham (1983, Appendix E).
Similarly, sampling of Juvenile Anadromous Habitat Study (JAHS) sites during 1983 and 1984
occurred in a systematic fashion within grids delineated at each site (Figure 8.1-8; Dugan et al.
1984, Suchanek et al. 1984a, 1985). Each 6 ft by 30 ft sampling cell was intended to be
relatively homogeneous with respect to temperature, turbidity, depth, velocity, cover and
substrate composition. Cells within a site were then selected such that the full range of
conditions were sampled. Analysis of the fish collections by beach seine and backpack
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electrofishing and the physical factors measured within each cell were used in the development
of habitat suitability curves (HSC) for juvenile salmon species (Suchanek et al. 1984a, 1985; also
see Section 8.1.1.3 Juvenile Salmon Rearing in the Middle Susitna River).
Surveys for juvenile anadromous and resident fish with monitoring of turbidity in areas sampled
led to a number of conclusions regarding the influence of turbid and clear water zones on habitat
utilization. Turbidity was found to be a significant factor in analysis of variance of catch rates
for Age 0 Chinook and coho juveniles (Dugan et al. 1984). Chinook juveniles were found to use
relatively turbid water greater than 30 NTU as cover (Dugan et al. 1984, Suchanek et al. 1984a).
In contrast, coho juveniles were found to prefer relatively clear water zones. Nevertheless,
separate HSC for turbid (>30 NTU) and clear water (<30 NTU) were only developed for
Chinook salmon juveniles, because there was insufficient data for coho salmon (Suchenek et al.
1984).
Turbidity was also considered an important factor incorporated into cover HSC for rainbow trout
adult, Arctic grayling adult, round whitefish adult and juveniles, and longnose sucker adult
(Suchanek et al. 1984b). Suchanek et al. (1984b) found these species utilized cover differently
depending upon whether using turbid or clear water. In general, rainbow trout and Arctic
grayling had higher catch rates in areas with lower turbidity levels while round whitefish and
longnose sucker had higher catch rates in more turbid areas (Suchanek et al. 1984b). Turbidity
levels were also considered an important factor affecting habitat utilization by burbot, humpback
whitefish, and Dolly Varden (Schmidt and Bingham 1983), but catch rates were insufficient for
developing HSC (Suchanek et al. 1984b). Adult burbot tended to be more common in turbid
mainstem and mixed water sources. Similar to round whitefish, humpback whitefish were also
more commonly captured in turbid mainstem and mixed water rather than clear water areas.
Dolly Varden were more commonly associated with tributaries and tributary mouths with
relatively low turbidity.
8.1.3. Ice Processes and Open Water Leads
A discussion of ice processes and open water leads was presented as part of RSP Section 7.6 and
is summarized herein because of their overall relevance when discussing physical processes. As
noted in Section 7.6, ice affects the Susitna River for approximately seven months of the year,
between October and May. When air and water temperatures drop below freezing in September
and October, border ice grows along the banks of the river, and frazil ice begins accumulating in
the water column and flowing downstream. Flowing ice eventually clogs the channel in shallow
or constricted reaches, or at tidewater, forming ice bridges. Frazil pans flowing downstream
accumulate against ice bridges, causing the ice cover to progress upstream. By January, much of
the river is under a stable ice cover, with the exception of persistent open leads corresponding
with warm upwelling water or turbulent, high-velocity flows. Flows generally drop slowly
throughout the winter until snowmelt commences in April. During April and May, river stages
rise and the ice cover weakens, eventually breaking into pieces and flushing downstream (R&M
1982a). Ice jams are recurrent events in some reaches of the river. If severe, jams can flood
upstream and adjacent areas, drive ice overbank onto gravel bars and into sloughs and side
channels, shear-off or scar riparian vegetation, and threaten infrastructure such as the Alaska
Railroad and riverbank property (R&M 1982a).
Ice processes were documented between the mouth of the Susitna River (RM 0) and the
proposed dam site (RM 184) between 1980 and 1985 (R&M 1981b, 1982b, 1983, 1984, 1985,
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1986). Winter observations have spanned a range of climatic conditions. The freeze-up period
of 1985 was unusually cold, with about twice the accumulated freezing-degree days as the long-
term average (R&M 1986), while the freeze-up period of 1984 was warm (R&M 1985). In the
1980s modeling studies, cold, average, and warm conditions were simulated using records from
the winters of 1971–1972, 1976–1977, and 1981–1982, respectively (Harza-Ebasco 1984). The
winter of 1971–1972 still stands as one of the coldest on record at Talkeetna; however, according
to the Western Regional Climate Data Center, the warmest winter on record occurred in 2002–
2003. Both freeze-up and break-up progressions were monitored using aerial reconnaissance.
Locations of ice bridges during freeze-up and ice jams during break-up were recorded each
season.
In addition to its effect on river morphology, riparian function, and sediment transport, ice
processes influence the freeze-up and ice cover on salmon spawning and overwintering habitat
areas. Water levels at certain sloughs in the Middle River and Lower River were monitored
during the winter to determine whether staging during freeze-up and ice cover diverted water
into side channels and sloughs (R&M 1984). Changes in water levels in spawning sloughs and
side channels as a result of ice processes can have adverse effects in several ways (Vining et al.
1985). First, inflows of cold mainstem water into areas with warmer groundwater upwelling can
result in longer incubation times. Secondly, large decreases in flows relative to flows during
spawning can result in some redds being dewatered and subjected to freezing.
Ice processes can also affect the quality of overwinter habitat (Brown et al 2011). For example,
anchor ice can reduce the amount of interstitial space between large cobbles and boulders, which
is used as cover and resting locations by salmonids. Large amounts of frazil ice drifting in the
water column can also cause fish to move location, which can be stressful under low temperature
conditions (Brown et al. 2011).
As part of winter studies, ADF&G mapped the location of open leads. Open leads typically
occurred in areas of groundwater upwelling or in areas of relatively high water velocity where
turbulence tends to maintain open areas. Barrett et al. (1985) reported that upwelling, bank
seepage, or open leads were present during the winter 1983 at 10 of 12 mainstem/side channel
sites in the Lower River with chum salmon spawning observed during 1984. Spawning in
sloughs was also associated the presence of upwelling, bank seepage, or open leads as well as the
presence of tributaries (Barrett et al. 1985).
Freeze-up and melt-out processes in the Middle River (between Gold Creek and Talkeetna) were
modeled using ICECAL, a numerical model developed by the USACE Cold Regions Research
and Engineering Laboratory (CRREL) (Harza-Ebasco 1984). The model utilized the outputs
from a temperature model developed for the river (SNTEMP) and empirical data on frazil
production and ice-cover progression derived from observations. Representative year types were
modeled under both the proposed 1980s Watana-only and Watana-Devils Canyon operations,
including a cold winter (1971–1972), a very warm winter (1976–1977), a warm winter (1982–
1983), and an average winter (1981–1982). The results of the model included predictions of the
extent of ice cover, the timing of ice-cover progression, ice surface elevations, and the inundated
area beneath the ice cover for selected cross-sections. The elevation of water flowing beneath
the ice was compared to the elevation necessary to overtop slough berms at selected fish habitat
study areas in the Middle River in order to assess the impacts of Project operation on winter flow
in these sloughs. Empirical data on frazil production and ice-cover progression was used to
estimate changes in ice-cover progression between tidewater and Talkeetna. Reservoir ice was
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simulated using a DYRESM model and calibrated to conditions at Eklutna Lake (Harza-Ebasco
1986).
Key findings of the 1980s modeling effort included the following (for the Watana-only
scenarios):
The open water reach would likely extend 44–57 miles downstream of the dam site.
Ice thicknesses were generally similar under project conditions, where ice was predicted
to occur.
Winter water surface elevations under ice would be 2–7 feet higher under project
conditions, and would result in the flooding of some sloughs with mainstem water in the
Middle River without mitigation.
Freeze-up would be delayed by 2–5 weeks in the fall, and ice-out would occur 5–7 weeks
earlier in the spring.
Ice jams during break-up would be reduced in severity post-project because of the
regulation of spring snowmelt flows.
8.1.4. Substrate Composition
Substrate composition is determined primarily by geomorphic processes that produce a state of
dynamic equilibrium with the upstream water and sediment supply by adjusting their physical
characteristics to the imposed conditions (Chorley et al. 1984; Lane 1955). These physical
characteristics, that include gradient, channel geometry, planform, and boundary materials
(stream bed and banks), form the habitat that is used by the aquatic and riparian organisms, and
they occur and adjust at a variety of spatial and temporal scales.
Substrate composition is an important factor contributing to quality of spawning, rearing, and
overwintering habitat quality (Bjornn and Reiser 1991). During the 1980s Su-Hydro studies,
substrate composition was typically described as part of characterizing the physical environment
at sampling sites. Species and life stage specific suitability of substrate can be described and
incorporated into instream flow modeling. Habitat suitability curves (HSC) development and
collection of substrate composition data at instream flow modeling sites was in important part of
the 1980s Su-Hydro studies (see Section 7, Habitat Utilization and Habitat Suitability Curve
Development Studies).
In addition, substrate composition, and more specifically the level of fines (particles less than
0.08 inches in diameter), were studied as part of chum and sockeye egg incubation studies (e.g.,
Vining et al. 1985). The presence of excessive amounts of fines may result primarily in two
types of adverse effects (Bjornn and Reiser 1991). The first is that fines can reduce the amount
of intergravel flow such that eggs do not receive sufficient oxygen and that waste products are
not removed from the redd. The second is that influxes of fines during incubation can entomb a
redd and prevent alevins from emerging. Vining et al. (1985) observed that slough habitats had
the highest level of fines, followed by side channel, tributary, and mainstem habitats (Figure 8.1-
9). However, sediment composition sampled directly from redds were much lower (Figure 8.1-
10). The difference in the amount of fines between redd samples and overall can be at least
partially explained by the redd digging process by salmon females which can remove substantial
amounts of fines (Bjornn and Reiser 1991). Vining et al. (1985) suggested that egg survival at
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Susitna River study sites approached zero when fines (< 0.08 inches in diameter) in redds
exceeded 16 percent (Figure 8.1-Figure 8.1-11).
One of the early conclusions from the surveys conducted during 1981 and 1982 was that little to
no salmon spawning occurred in the main channel habitats because of high water velocities and
unsuitable spawning substrate. Mainstem substrates generally consisted of boulder and cobble
size materials with interstitial spaces filled with a grout-like mixture of small gravels and glacial
sands (Estes and Schmidt 1983). In contrast, the more protected side channels and side sloughs
often included smaller substrates that were occasionally disturbed during high flow events that
breached berms at the head of the channel or slough. In addition, many side channels and
sloughs had upwelling from hyporheic or groundwater sources that provided more stable and
higher temperatures during egg incubation than mainstem water (Hoffman et al. 1983).
Fines can also adversely affect overwintering habitat for juvenile salmon. As temperatures cool
during the late fall and winter, salmonids tend to use areas with low water velocity such as deep
pools, high levels of cover such as large woody debris or coarse substrate (large cobble and
boulders), and areas with upwelling (Brown et al. 2011). High levels of fines can fill the
interstitial spaces between coarse substrate which reduces the amount of available habitat and
can reduce upwelling groundwater (Vining et al. 1985).
8.2. Susitna-Watana 2013-2014 Studies
In terms of the 2013-2014 studies, essentially all of the processes identified during the 1980s
studies and described above (e.g., groundwater- upwelling, intergravel water temperature, water
turbidity and water clarity, ice processes, and substrate composition) will be evaluated as part of
one or more of the proposed studies. In addition, several other processes that were not explicitly
studied or that were not studied in any detail during the 1980s will also be evaluated. These
include detailed fluvial geomorphology studies/processes (see RSP 6.5 and 6.6), studies of large
woody debris recruitment (see RSP 6.5.4.9) and an extensive evaluation of riparian community
processes and interactions with flows (see RSP 8.6).
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10. TABLES
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Table 2.1-1. Types of instream flow and fish related studies conducted as part of the Su-Hydro Fish and Aquatics Study Program during 1981 to 1986.
Year Adult Anadromous Studies Resident and Juvenile Studies Aquatic Habitat Studies
1981
Mainstem escapement monitoring (gillnet,
electrofishing, fishwheel, and sonar sampling); radio-
tracking, run timing, age and length, sex ratios, aerial
and foot spawning surveys between Cook Inlet and
Devils Canyon plus the Yentna River and selected
tributaries (ADF&G 1981a).
Resident fish distribution, abundance, age, length,
sex composition, and floy tagging from Cook Inlet to
Devils Canyon (Delaney et al. 1981a) and upstream
of Devils Canyon (Delaney et al. 1981b);
Juvenile anadromous winter and summer distribution,
abundance, age, and length (Delaney et al. 1981c).
Measurement of physical parameters including
hydrology (flow), hydraulics (water stage and
velocity), water quality, and morphologic mapping at
selected sites (Estes et al. 1981).
1982
Mainstem escapement monitoring (fishwheels, sonar)
downstream of Devils Canyon, tagging, radio-
tracking, run timing, age composition, fecundity,
aerial and foot spawning surveys, eulachon and
Bering cisco spawning surveys (ADF&G 1983).
Chum and sockeye egg incubation and intergravel
water monitoring in the Middle River (Hoffman et al.
1983);
Distribution and abundance of resident fish and
juvenile salmon downstream of Devils Canyon, radio-
tracking of resident fish, emergence and outmigration
of juvenile salmon, food habitats of juvenile salmon
(Schmidt et al. (1983);
Distribution and abundance of resident fish upstream
of Devils Canyon, tributary habitat, passage barriers,
and fish distribution/abundance, lake habitat and fish
distribution (Sautner and Stratton 1983).
Characterization of spawning and rearing habitat for
anadromous and resident fish (Estes and Schmidt
1983);
Slough hydrogeology (Burgess 1983);
Side slough access by spawning salmon (Trihey
1982);
1983
Mainstem escapement monitoring (fishwheels, sonar)
downstream of Devils Canyon, tagging, run timing,
age composition, fecundity, aerial and foot spawning
surveys, eulachon and Bering cisco spawning
surveys (Barrett et al. 1984).
Outmigration of juvenile salmon upstream of
Talkeetna, distribution and abundance of juvenile
salmon upstream of Talkeetna (Schmidt et al.
1984a);
Temperature effects on chum and sockeye salmon
egg development (Wangaard and Burger 1983);
Access and transmission corridor aquatic study
(Schmidt et al. 1984b)
Collection of hydrologic and water quality information
and information needed for modeling adult salmon
spawning habitat and access into selected sloughs
used for spawning (Sautner et al. 1984);
Juvenile salmon and resident fish rearing suitability
criteria and habitat modeling (Schmidt et al. 1984a);
Assessment of access into Indian and Portage
creeks by spawning salmon (Trihey 1983).
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Year Adult Anadromous Studies Resident and Juvenile Studies Aquatic Habitat Studies
1984
Mainstem escapement monitoring (fishwheels, sonar)
downstream of Devils Canyon, tagging, run timing,
age composition, aerial and foot spawning surveys
(Barrett et al. 1985).
Migration and growth of juvenile salmon (Roth and
Stratton 1985);
Abundance and distribution of juvenile salmon
(Suchanek et al. 1985);
Abundance, distribution, and radio-tracking of
resident fish in the lower Middle River (Sundet and
Pechek 1985);
Invertebrate food sources for Chinook salmon
juveniles (Hansen and Richards 1985).
Water quality monitoring and chum egg incubation
study in the lower Middle River (Vining et al. 1985);
Intergravel water temperature, substrate composition,
chum spawning habitat, and egg incubation in the
Lower River (Bigler and Levesque 1985)
Collection of hydrologic and water quality information
and information needed for modeling spawning and
rearing flow:habitat relationships (Quane et al. 1985);
Instream flow relationships for juvenile salmon
(Suchanek et al. 1985);
Access of spawning salmon into tributaries
downstream of Talkeetna (Ashton and Trihey 1985);
Chum spawning habitat in the Lower River instream
flow model development (Bigler and Levesque 1985).
1985
Mainstem escapement monitoring (fishwheels)
downstream of Devils Canyon, tagging, run timing,
age composition, aerial and foot spawning surveys
(Thompson et al. 1986);
Summary of fishery data (Hoffman 1985).
Winter distribution of burbot and rainbow trout
(Sundet 1986);
Winter distribution, abundance, movement, and
length of juvenile Chinook and coho salmon (Stratton
1986);
Migration and growth of juvenile salmon (Roth et al.
1986).
Preliminary results of primary productivity and
macroinvertebrate monitoring in the Susitna and
Kasilof rivers (Wilson 1985),
Characterization of aquatic habitats in the lower
Middle River (Aaserude et al. 1985);
Juvenile Chinook salmon instream flow modeling
(Steward et al. 1985);
Response of water surface area to discharge in the
Yentna to Talkeetna Reach (Ashton and Klinger-
Kingsley 1985) and Talkeetna to Devils Canyon
Reach (Klinger Kingsley et al. 1985).
Development of quantitative relationships regarding
the influences of incremental changes in streamflow,
stream temperature and water quality on fish habitats
in the Middle River (Trihey and Associates and Entrix
1985).
1986 No field, laboratory, or desktop studies. No field, laboratory, or desktop studies. Chum salmon spawning instream flow modeling
(Trihey and Hilliard 1986).
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Table 3.1-1. Designated Fish Habitat Sites surveyed June through September 1982. Source: Estes and Schmidt (1983).
Reach Site Historic River Mile
Lower River
GOOSE CREEK 2 AND SIDE CHANNEL 73.1
WHITEFISH SLOUGH 78.7
RABIDEUX CREEK AND SLOUGH 83.1
SUNSHINE CREEK AND SIDE CHANNEL 85.7
BIRCH CREEK AND SLOUGH 88.4
Middle River
WHISKERS CREEK AND SLOUGH 101.2
SLOUGH 6A 112.3
LANE CREEK AND SLOUGH 8 113.6
SLOUGH 8A 125.3
SLOUGH 9 129.2
4th OF JULY CREEK-MOUTH 131.1
SLOUGH 11 135.3
INDIAN RIVER—MOUTH 138.6
SLOUGH 19 140.0
SLOUGH 20 140.1
SLOUGH 21 142.0
PORTAGE CREEK-MOUTH 148.8
Table 3.1-2. Description of habitat zones sampled at Designated Fish Habitat Sites: June through September 1982 (From
Estes and Schmidt 1983).
Zone Code Description
1 Areas with a tributary or ground water source which are not influenced by mainstem stage and which usually
have a significant1 surface water velocity.
2 Areas with a tributary or ground water source which have no appreciable1 surface water velocity as a result of a
hydraulic barrier created at the mouth of a tributary or slough by mainstem stage.
3 Areas of significant surface water velocities, primarily influenced by the mainstem, where tributary or slough
water mixes with the mainstem water.
4 Areas of significant water surface velocities which are located in a slough or side channel above a tributary
confluence (or in a slough where no tributary is present) when the slough head is open.
5 Areas of significant water surface velocities which are located in at slough or side channel below a tributary
confluence when the slough head is open.
6
Backwater areas with no appreciable surface water velocities which result from a hydraulic barrier created by
mainstem stage which occur in a slough or side channel above a tributary confluence (or in a slough or side
channel where no tributary is present), when the head of the slough is open.
7
Backwater areas with no appreciable surface water velocities which result from a hydraulic barrier created by
mainstem stage which occur in a slough or side channel below a tributary confluence, when the head of the
slough is open.
8 Backwater areas consisting of mainstem eddies.
9 A pool with no appreciable surface water surface velocities which is created by a geomorphological feature of a
free-flowing zone or from a hydraulic barrier created by a tributary; not created as a result of mainstem stage.
Notes:
1 “Significant” and “appreciable” surface water velocities mean a velocity of at leas t 0.5 ft/sec. However, there
are site-specific exceptions to this, based on local morphology.
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Table 3.1-3. Aggregate Hydraulic (H), Water Source (W) and Velocity (V) zones. Source: Estes and Schmidt (1983),
Schmidt et al. (1983).
Aggregate Zone Habitat Zone Included Definition
H-I 1, 4, 5, 9 not backed up by mainstem
H-II 2, 6, 7, 8 backed up by mainstem
H-III 3 mainstem
W-I 1, 2 tributary water and/or ground water only
W-II 4, 6, 8, sometimes 3 mainstem water only
W-III 5, 7, sometimes 3 mixed water sources
V-I1 1, 3, 4, 5 Fast water
V-II1 2, 6, 7, 8, 9 Slow water
Notes:
1 The habitat zones included in aggregate zones V-I and V-II were not provided in the source documents. Zone
descriptions were used to classify which zones were fast and slo w water.
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Table 3.1-4. JAHS sample sites for the AJ and AH components of the Aquatic Studies Program during 1983
and 1984.
Site
River
Mile
Macro-
habitat
Type2
1983/1984 Sampling1
1982
DFH
Site
1982
SFH
Site
1981
Sample
Site
Fish
Distri-
bution
Site
RJHAB
Modeling
Site
IFIM
Modeling
Site
Eagles Nest Side Channel3 36.2 SC X X
Hooligan Side Channel3 36.2 SC X X
Kroto Slough Head 36.3 SS X X
Rolly Creek Mouth 39.0 T X X
X
Bear Bait Side Channel 42.9 SC X X
Last Chance Side Channel 44.4 SC X X
Rustic Wilderness Side Channel 59.5 SC X X
Caswell Creek Mouth3 63.0 T X X
X X
Island Side Channel 63.2 SC X X X
Mainstem West Bank 74.4 SC X
X
Goose 2 Side Channel 74.8 SC X X
X
Circular Side Channel 75.3 SC X
X
Sauna Side Channel 79.8 SC X
X
Sucker Side Channel3 84.8 SC X X
Beaver Dam Slough3 86.3 T X X
Beaver Dam Side Channel3 86.3 SC X X
Sunset Side Channel3 86.9 SC X
X
Sunrise Side Channel3 87.0 SC X X
Birch Slough3 89.4 T X X
X
X
Trapper Creek Side Channel 91.6 SC X X X
Whiskers Creek Slough 101.2 SS/SC X X
X
X
Whiskers Creek4 101.2 T X
X
X
Slough 3B 101.4 SS X
Mainstem at head of Whiskers
Creek Slough4 101.4 SC X
Chase Creek 106.9 T X
X
Slough 5 107.6 US X X
Oxbow I 110.0 SC/SS X
Slough 6A 112.3 US X X
X
X
Mainstem above Slough 6A4 112.4 SC X
Lane Creek4 113.6 T X
X
X
Slough 8 113.6 SS X X
X
Mainstem II 114.4 SC/SS X
X
Lower McKenzie Creek4 116.2 T X
X
Upper McKenzie Creek4 116.7 T X
X
Side Channel below Curry4 117.8 SC X
Oxbow II4 119.3 SC/SS X
Slough 8A 125.3 SS X
X X
Side Channel 10A 127.1 SC X X
Slough 9 129.2 SS/SC X
X X
Slough/Side Channel 10 133.8 SC/SS X
X
X X
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Site
River
Mile
Macro-
habitat
Type2
1983/1984 Sampling1
1982
DFH
Site
1982
SFH
Site
1981
Sample
Site
Fish
Distri-
bution
Site
RJHAB
Modeling
Site
IFIM
Modeling
Site
Lower Side Channel 114 134.6 SC X
X
Slough 11 135.3 SS X
X
X
Upper Side Channel 114 136.2 SC X
X
Indian River-Mouth 138.6 T X
X
X
Indian River-TRM 10.1 138.6 T X
Slough 194 140.0 US X
X
Slough 204 140.1 SS/SC X
X
X
Side Channel 21 140.6 SC
X
Slough 21 142.0 SS/SC
X X
Slough 22 144.3 SS/SC X X
Jack Long Creek4 144.5 T X
X
Portage Creek Mouth 148.8 T X
X
X
Portage Creek TRM 4.2 148.8 T X
Portage Creek TRM 8.0 148.8 T X
Notes:
1 Sites from RM 36.2 to RM 91.6 were sampled in 1984 (Suchanek et al. 1985). Sites from RM 101.2 to 148.8
were sampled in 1983 (Dugan et al. 1984).
2 T – Tributary
US – Upland Slough
SS – Side Slough
SC – Side Channel
3 Located within representative side channel or slough complexes mapped by Ashton and Klinger-Kingsley
(1985).
4 Sites sampled less than 3 times in 1983.
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Table 3.3-1. Locations, descriptions and selection rationale of final Focus Areas for detailed study in the Middle River Segment of the Susitna River. Focus Area identification numbers (e.g., Focus Area 184) represent the truncated Project River Mile (PRM) at the downstream end
of each Focus Area.
Focus
Area ID
Common
Name Description
Geomorphic
Reach
Location (PRM)
Area
Length
(mi)
Habitat Types Present
Fish use in
1980s
Instream Flow
Studies in 1980s
Rationale for Selection Main Channel, Single Main Channel, Split Side Channel Tributary Mouth Side Slough Upland Slough Beaver Complex Upstream Downstream Spawning Rearing IFG DIHAB RJHAB Focus
Area-
184
Watana Dam
Area approximately 1.4
miles downstream of dam
site
MR-1 185.7 184.7 1.0 X X X N/A N/A N/A N/A N/A Focus Area-184 length comprises 50% of MR-1 reach length (2 miles long) and contains split
main channel and side channel habitat present in this reach.
Focus
Area-
173
Stephan Lake,
Complex
Channel
Wide channel near
Stephan Lake with
complex of side channels
MR-2 175.4 173.6 1.8 X X X X N/A N/A N/A N/A N/A
Focus Area-173 contains a complex of main channel and off-channel habitats within wide
floodplain. Represents greatest channel complexity within MR-2. Reach MR-2 is 15.5 miles long
and channel is generally straight with few side channels and moderate floodplain width (2-3 main
channel widths).
Focus
Area-
171
Stephan Lake,
Simple Channel
Area with single side
channel and vegetated
island near Stephan Lake
MR-2 173.0 171.6 1.4 X X X N/A N/A N/A N/A N/A
The single main channel with wide bars, single side channel and moderate floodplain channel
width in Focus Area-171 are characteristic of MR-2. Reach MR-2 channel morphology is
generally straight with few side channels and moderate floodplain width (2-3 main channel
widths).
Focus
Area-
151
Portage Creek Single channel area at
Portage Creek confluence MR-5 152.3 151.8 0.5 X X X X
Focus Area-151 is a single main channel and thus representative of the confined Reach MR-5.
Portage Creek is a primary tributary of the Middle Segment and the confluence supports high fish
use.
Focus
Area-
144
Side Channel
21
Side channel and side
slough complex
approximately 2.3 miles
upstream Indian River
MR-6 145.7 144.4 1.3 X X X X X X X X X
Focus Area-144 contains a wide range of main channel and off-channel habitats, which are
common features of Reach MR-6. Side Channel 21 is a primary salmon spawning area. Reach
MR-6 is 26 miles long (30% of Middle Segment length) and is characterized by a wide floodplain
and complex channel morphology with frequent channel splits and side channels.
Focus
Area-
141
Indian River
Area covering Indian River
and upstream channel
complex
MR-6 143.4 141.8 1.6 X X X X X X X X X
Focus Area-141 includes the Indian River confluence, which is a primary Middle Susitna River
tributary, and a range of main channel and off-channel habitats. Channel and habitat types
present in Focus Area-141 are typical of complex Reach MR-6. High fish use of the Indian River
mouth has been documented and DIHAB modeling was performed in main channel areas.
Focus
Area-
138
Gold Creek
Channel complex including
Side Channel 11 and
Slough 11
MR-6 140.0 138.7 1.3 X X X X X X X X X
The Focus Area-138 primary feature is a complex of side channel, side slough and upland slough
habitats, each of which support high adult and juvenile fish use. Complex channel structure of
Focus Area-138 is characteristic of Reach MR-6. IFG modeling was performed in side channel
habitats.
Focus
Area-
128
Skull Creek
Complex
Channel complex including
Slough 8A and Skull Creek
side channel
MR-6 129.7 128.1 1.6 X X X X X X X X X
Focus Area-128 consists of side channel, side slough and tributary confluence habitat features
that are characteristic of the braided MR-6 reach. Side channel and side slough habitats support
high juvenile and adult fish use and habitat modeling was completed in side channel and side
slough habitats.
Focus
Area-
115
Lane Creek
Area 0.6 miles downstream
of Lane Creek, including
Upland Slough 6A
MR-7 116.5 115.3 1.2 X X X X X X X X
Focus Area-115 contains side channel and upland slough habitats that are representative of MR-
7. Reach MR-7 is a narrow reach with few braided channel habitats. Upland Slough 6A is a
primary habitat for juvenile fish and habitat modeling was done in side channel and upland slough
areas.
Focus
Area-
104
Whiskers
Slough Whiskers Slough Complex MR-8 106.0 104.8 1.2 X X X X X X X X X X X
Focus Area-104 contains diverse range of habitat, which is characteristic of the braided,
unconfined Reach MR-8. Focus Area-104 habitats support juvenile and adult fish use and a
range of habitat modeling methods were used in side channel and side slough areas.
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Table 4.1-1. Deployment of fishwheel (F) and sonar stations (S) from 1981 to 1985. Sources: ADF&G (1982), ADF&G (1983b), Barrett et al. (1984), Barrett et al. (1985),
Thompson et al. (1986).
Station River Mile
1981 1982 1983 1984 1985
Gear
Period of
Operation Gear
Period of
Operation Gear
Period of
Operation Gear
Period of
Operation Gear
Period of
Operation
Flathorn Station 22 4F 6/29 to 9/3 4F-6F 5/26 to 9/3
Susitna Station 26.7 2F, 2S 6/27 to 9/2 2F, 2S 7/1 to 9/5
Yentna Station 28, TRM
04
2F, 2S 6/29 to 9/7 2F, 2S 6/27 to 9/5 2F, 2S 6/30 to 9/5 2F, 2S 7/1 to 9/5
Sunshine
Station
80 4F, 2S 6/23 to 9/15 4F, 2S 6/4 to 10/1 4F 6/3 to 9/11 4F 6/4 to 9/10 4F 6/3 to 9/10
Talkeetna
Station
103 4F, 2S 6/22 to 9/15 4F, 2S 6/5 to 9/14 4F 6/7 to 9/12 4F 6/3 to 9/11
Curry Station 120 2F 6/15 to 9/21 2F 6/9 to 9/18 2F 6/9 to 9/14 2F 6/9 to 9/14 2F 6/10 to 9/12
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Table 4.1-2. Number of fish radio-tagged by year in the Middle Susitna River (MR) and Lower Susitna River (LR).
Source: ADF&G (1981), ADF&G (1983a), Schmidt et al. (1983), Sundet and Wenger (1984), Sundet and Pechek (1985),
Sundet (1986).
Species 1981 1982 1983 1984
Chinook salmon 16 – MR 16 – MR
Coho salmon 10 – MR 16 – MR
Chum salmon 11 – MR 18 – MR
Rainbow trout 5 – LR 29 – MR 36 – LR
13 – MR
Burbot 5 – LR 4 – MR 14 – LR
3 – MR1
Arctic grayling 6 – MR
1. The position of three radio-tagged burbot were reported in Sundet and Pechek (1985), but the number tagged was not.
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Table 4.1-3. Deployment of incline plane traps from 1982 to 1985. Stations with two traps had one each river bank. S=Stationary, M=Mobile. Sources: Schmidt et al.
(1983), Roth et al. (1984), Roth and Stratton (1985), Roth et al. (1986)
Station
River
Mile
1982 1983 1984 1985
No.
Traps
Period of
Operation
No.
Traps
Period of
Operation
No.
Traps
Period of
Operation
No.
Traps
Period of
Operation
Flathorn Station 22.4 1 S
1 M
5/20 to 10/1
7/12 to 9/13
2 S
1 M
5/27 to 9/23
6/6 to 8/24
Talkeetna Station 103.0 1 S 6/18 to 10/12 2 S 5/18 to 8/30 2 S 5/14 to 10/6 1 S 5/27 to 10/12
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Table 4.2-1. Sites sampled in the Middle Susitna River 1981 to 1985. Does not included selected habitat sites (SFH) sampled during 1981 and 1982. Macrohabitat type
was not reported for all sites. Source: Delaney et al. (1981a), Schmidt et al. (1983), Schmidt et al. 1984, Suchanek et al. (1985), Sundet and Pechek (1985), Sundet (1986),
Stratton (1986).
Site RM
Macro-
habitat
Type
1981
Habitat
Locations
1982
DFH
Site
1983
JAHS
Site
1984 1985
JA
Tagging/
Marking
Site
Resident
Fish JAHS
JA
Sampling
Site
Whiskers Creek Slough 101.2 SS/SC X X X X
Whiskers Creek 101.2 T X X X
Slough 3B 101.4 SS X
Mainstem at head of Whiskers
Creek Slough 4
101.4 SC X
Chase Creek 106.9 T X
Slough 5 107.6 US X
Oxbow I 110 SC/SS X
Slough 6A 112.3 US X X X X X
Mainstem above Slough 6A 112.4 SC X
Lane Creek 113.6 T X X X X
Slough 8 113.6 SS X X
Mainstem II 114.4 SC/SS X X
Lower McKenzie Creek 116.2 T X
Upper McKenzie Creek 116.7 T X
Side Channel below Curry 117.8 SC X
Oxbow II 119.3 SC/SS X
Mainstem Susitna – Curry 120.7 X
Susitna Side Channel 121.6 X
Slough 8B 122.2 X
Moose Slough 123.5 X
Mainstem Susitna – Gravel Bar 123.8 X
Skull Creek 124.7 X
Slough 8A 125.3 SS X X X X X X
Side Channel 10A 127.1 SC X X
Slough 9 129.2 SS/SC X X X
Fourth of July Creek – Mouth 131.1 X X X
Slough 9A 133.6 X
Slough/Side Channel 10 133.8 SC/SS X X X X
Lower Side Channel 11 134.6 SC X
Slough 11 135.3 SS X X X X
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Site RM
Macro-
habitat
Type
1981
Habitat
Locations
1982
DFH
Site
1983
JAHS
Site
1984 1985
JA
Tagging/
Marking
Site
Resident
Fish JAHS
JA
Sampling
Site
Slough 14 135.9 X
Upper Side Channel 11 136.2 SC X X
Mainstem Susitna Gold Creek 136.9 X
Slough 15 137.2 X
Slough 16 137.7 X
Mainstem West Bank 137.3 to 138.3 X
Indian River – Mouth 138.6 T X X X X X
Indian River – TRM 1.9 138.6 X
Indian River – TRM 2.3 138.6 X
Indian River – TRM 10.1 138.6 T X
Indian River – TRM 11.9 138.6 X
Indian River TRM 0.0 to 12.3 138.6 X X
Slough 17 138.9 X
Slough 19 140 US X X X X
Slough 20 140.1 SS/SC X X X X X X
Side Channel 21 X
Slough 21 142 SS/SC X X X
Anna Creek Slough 143.2 X
Slough 22 144.3 SS/SC X X X
Jack Long Creek 144.5 T X X
Mainstem Susitna – Island 146.9 X
Mainstem 147.0 to 148.0 X
Portage Creek Mouth 148.8 T X X X X X
Portage Creek TRM 4.2 148.8 T X
Portage Creek TRM 8.0 148.8 T X
Mainstem Eddy 150.1 X
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Table 4.2-2. Sites sampled in the Lower Susitna River 1981 to 1984. Does not included selected habitat sites (SFH) sampled during 1981 and 1982. Macrohabitat type
was not reported for all sites. Source: Delaney et al. (1981a), Schmidt et al. (1983), Schmidt et al. (1984), Suchanek et al. (1985), Sundet and Pechek (1985), Sundet
(1986), Stratton (1986).
Site RM
Macro-
habitat
Type
1981
Habitat
Locations
1982
DFH
Site
1983
JAHS
Site
1984
JA
Tagging/
Marking
Site
Resident
Fish JAHS
Alexander Creek 10.1 X
Anderson Creek 23.8 X
Kroto Slough Mouth 30.1 X
Mainstem Susitna Slough 31.0 X
Eagles Nest Side Channel 36.2 SC X
Hooligan Side Channel 36.2 SC X
Kroto Slough Head 36.3 SS X
Mid Kroto Slough 36.3 X
Rolly Creek Mouth 39.0 T X
Deshka River 40.6 X
Bear Bait Side Channel 42.9 SC X
Delta Islands 44.0 X
Last Chance Side Channel 44.4 SC X
Little Willow Creek 50.5 X
Rustic Wilderness 58.1 X
Rustic Wilderness Side Channel 59.5 SC X
Kashwitna River 61.0 X
Caswell Creek Mouth 63.0 T X X
Island Side Channel 63.2 SC X
Slough West Bank 65.6 X
Sheep Creek Slough 66.1 X
Goose Creek 72.0 & 73.1 X
Mainstem West Bank 74.4 SC X X
Goose 2 Side Channel 74.8 SC X X
Circular Side Channel 75.3 SC X
Montana Creek 77.0 X
Sauna Side Channel 79.8 SC X
Rabideaux Creek and Slough 83.1 X
Mainstem 1 84.0 X
Sucker Side Channel 84.8 SC X
Sunshine Creek 85.7 X
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Site RM
Macro-
habitat
Type
1981
Habitat
Locations
1982
DFH
Site
1983
JAHS
Site
1984
JA
Tagging/
Marking
Site
Resident
Fish JAHS
Sunshine Creek and Side Channel 85.7 X
Beaver Dam Slough 86.3 T X
Beaver Dam Side Channel 86.3 SC X
Sunset Side Channel 86.9 SC X
Sunrise Side Channel 87.0 SC X
Birch Creek Slough 88.4 X
Birch Creek 89.2 T X X
Birch Creek and Slough 88.4 X
Trapper Creek Side Channel 91.6 SC X
Whitefish Slough 78.7 X
Cache Creek Slough 95.5 X
Cache Creek 96.0 X
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Table 4.3-1. Fish community in the Susitna River drainage. Source: Jennings (1985), Delaney et al. (1981b).
Common Name Scientific Name
Susitna River Segment
Tributaries Lakes Lower
Middle River1
Upper Lower Upper
Arctic grayling Thymallus arcticus X X X X X
Dolly Varden Salvelinus malma X X X X X
Humpback whitefish Coregonus pidschian X X X
Round whitefish Prosopium cylindraceum X X X X X
Burbot Lota lota X X X X
Longnose sucker Catostomus catostomus X X X X X
Sculpin2 Cottid X X X X X
Eulachon Thaleichthys pacificus X
Bering cisco Coregonus laurettae X
Threespine stickleback Gasterosteus aculeatus X X X
Ninespine stickleback Pungitius pungitius X
Arctic lamprey Lethenteron japonicum X X X
Chinook salmon Oncorhynchus tshawytscha X X X X X
Coho salmon Oncorhynchus kisutch X X X
Chum salmon Oncorhynchus keta X X X
Pink salmon Oncorhynchus gorbuscha X X X
Sockeye salmon Oncorhynchus nerka X X X
Rainbow trout Oncorhynchus mykiss X X X
Northern pike Esox lucius X ? X X
Lake trout Salvelinus namaycush X X
Notes:
1 The Lower Middle River is from the confluence of the Chulitna River to Devils Canyon. Upper Middle River is from Devils Cree k to the proposed Watana
Dam Site.
2 Sculpin primarily include slimy sculpin (C. cognatus), but may also include coastrange sculpin (C. aleuticus), sharpnose sculpin (C. acuticeps), Pacific
staghorn sculpin (Leptocottus armatus) and possibly others.
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Table 4.3-2. Information from Buckwalter (2011) Synopsis of ADF&G’s Upper Susitna Drainage Fish Inventory, August 2011.
Stream River Mile Date Lifestage
Number of
Fish
Method
Reference
Above Devils Canyon (RM 152)
Fog Creek 176.7 8/1/2003 adults 2 helicopter/foot Buckwalter 2011, AWC Survey ID: FSS03USU01
Tsusena Creek 181.3 8/1/2003 adults 1 helicopter/foot Buckwalter 2011, AWC Survey ID: FSS03USU02
Fog Creek 176.7 8/13/2003 juveniles 5 electrofishing Buckwalter 2011, AWC Survey ID: FSS0305A01
Fog Creek Trib 176.7 8/6/2011 juveniles 8 electrofishing Buckwalter 2011, AWC Survey ID: FSS1104c01
Fog Creek 176.7 8/6/2011 redds Survey ID: FSS1104B01
Above Watana Dam Site (RM 184)
Kosina Creek 201 8/14/2003 juveniles 1 electrofishing Buckwalter 2011, AWC Survey ID: FSS0306A01
Oshetna River 225 8/14/2003 juveniles 3 electrofishing Buckwalter 2011, AWC Survey ID: FSS0306A05
Kosina Creek 201 8/15/2003 juveniles 2 electrofishing Buckwalter 2011, AWC Survey ID: FSS0307A06
Kosina Creek 201 7/27/2011 adults 1 helicopter/foot Buckwalter 2011, Survey ID: FSS1101G04
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Table 4.3-3. Estimated Arctic grayling population sizes in tributaries to the upper Middle and Upper Susitna
River during 1981 and 1982. Source: Delaney et al. (1981b), Sautner and Stratton (1983).
Stream River Mile
19811 19821
Point Estimate
(fish)
95%
Confidence Interval
(fish)
Point Estimate
(fish)
Point Estimate
(fish/mile)
Oshetna River 233.4 2,017 1,525-2,976 2,426 1,103
Goose Creek 224.9 1,327 1,016-1,913 949 791
Jay Creek 203.9 1,089 868-1,462 1,592 455
Kosina Creek 202.4 2,787 2,228-3,720 5,544 1,232
Watana Creek 190.4 3,925 324
Deadman Creek 186.7 979 604-2,575 734 1,835
Tsusena Creek 181.3 1,000 743-1,530
Fog Creek 176.7 176 115-369 440
Upper Susitna River 10,279 9,194-11,654 16,3462
Notes:
1 Fish densities were not reported for 1981. Confidence intervals were not reported for 1982.
2 Total of point estimates from 1982 plus 1981 point estimates for Tsusena and Fog creeks.
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Table 4.3-4. Chinook salmon escapement survey results from 1982 to 1985 upstream of RM 152. Surveys conducted by helicopter. Source: ADF&G (1983a), Barrett et
al. (1984), Barrett et al. (1985), Thompson et al. (1986).
Stream
1982 1983 1984 1985 # Flights Date of Peak Count Peak Count APA Source/PDF Page # Flights Date of Peak Count Peak Count APA Source/PDF Page # Flights Date of Peak Count Peak Count APA Source/PDF Page # Flights Date of Peak Count Peak Count APA Source/PDF Page Cheechako Cr 9 6-Aug 16 589/314 2 1-Aug 25 1450/111 7 1-Aug 29 2748/60, 506 11 24-Jul 18 3412/127
Chinook Cr 5 6-Aug 5 589/314 2 1-Aug 8 1450/111 7 1-Aug 15 2748/60, 506 11 23-Aug 1 3412/128
Devil Cr 5 0 589/314 1 1-Aug 1 1450/111 6 0 2748/60, 506 11 0 3412/128
Fog Cr 0 2748/60 0 2748/60 4 21-Jul 2 2748/60, 506 3 0 3412/128
Bear Cr 0 0 2748/151 4 0 2748/506 3 0 3412/128
Tsusena Cr 0 0 2748/151 4 0 2748/507 3 0 3412/128
Deadman Cr 0 0 3 0 2748/507 0 Watana Cr 0 0 2 0 2748/507 0
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Table 5.1-1. Periodicity of Chinook salmon utilization among macro-habitat types in the Middle (RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna
River by life history stage. In the Upper Segment (RM 260 – RM 184), adult Chinook are believed to exhibit similar habitat use to that shown for the Middle Segment,
while juvenile Chinook rearing and migration timing in this segment is not known. Shaded areas indicate timing of utilization by macro-habitat type and dark gray
areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Middle Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Rearing
Age 0+ Migration
Age 1+ Rearing
Age 1+ Migration
Lower Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Rearing
Age 0+ Migration
Age 1+ Rearing
Age 1+ Migration
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Table 5.1-2. Periodicity of sockeye salmon utilization among macro-habitat types in the Middle (RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna
River by life history stage. Shaded areas indicate timing of utilization by macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Middle Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Rearing
Age 0+ Migration
Age 1+ Rearing
Age 1+ Migration
Lower Susitna River
Adult Migration1
Spawning
Incubation
Fry Emergence
Age 0+ Rearing
Age 0+ Migration
Age 1+ Rearing
Age 1+ Migration
Notes:
1 First run sockeye migration timing occurs during May and June and second run sockeye migration is July through September.
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Table 5.1-3. Periodicity of chum salmon utilization among macro-habitat types in the Middle (RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna River
by life history stage. Shaded areas indicate timing of utilization by mac ro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Middle Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Rearing
Age 0+ Migration
Lower Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Rearing
Age 0+ Migration
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Table 5.1-4. Periodicity of coho salmon utilization among macro-habitat types in the Middle (RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna River
by life history stage. Shaded areas indicate timing of utilization by macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Middle Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Rearing
Age 0+ Migration
Age 1+ Rearing
Age 1+ Migration
Age 2+ Rearing
Age 2+ Migration
Lower Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Rearing
Age 0+ Migration
Age 1+ Rearing
Age 1+ Migration
Age 2+ Rearing
Age 2+ Migration
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Table 5.1-5. Periodicity of pink salmon utilization among macro-habitat types in the Middle (RM 184 – 98.5) and Lower (RM 98.5 – 0.0) segments of the Susitna River
by life history stage. Shaded areas indicate timing of utilization by macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Middle Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Migration
Lower Susitna River
Adult Migration
Spawning
Incubation
Fry Emergence
Age 0+ Migration
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Table 5.1-6. Periodicity of rainbow trout utilization among macro-habitat types in the Susitna River by life history stage. Shaded areas indicate timing of utilization by
macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Holding
Adult Migration
Spawning
Incubation
Fry Emergence
Juvenile Rearing
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Table 5.1-7. Periodicity of Arctic grayling utilization among macro-habitat types in the Susitna River by life history stage. Shaded areas indicate timing of utilization by
macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Holding
Adult Migration
Spawning
Incubation
Fry Emergence
Juvenile Rearing
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Table 5.1-8. Periodicity of burbot utilization among macro-habitat types in the Susitna River by life history stage. Shaded areas indicate timing of utilization by macro-
habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Holding
Adult Migration
Spawning
Incubation
Juvenile Migration
Juvenile Rearing
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Table 5.1-9 Periodicity of round whitefish utilization among macro-habitat types in the Susitna River by life history stage. Shaded areas indicate timing of utilization by
macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Holding
Adult Migration
Spawning
Incubation
Fry Emergence
Juvenile Migration
Juvenile Rearing
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Table 5.1-10. Periodicity of humpback whitefish utilization among macro-habitat types in the Susitna River by life history stage. Shaded areas indicate timing of
utilization by macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Holding
Adult Migration
Spawning
Incubation
Fry Emergence
Juvenile Migration
Juvenile Rearing1
Notes:
1 A portion of juvenile humpback whitefish may utilize estuarine habitats to rear during the first two years of life.
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Table 5.1-11 Periodicity of longnose sucker in the Susitna River by life history stage and habitat type. Shaded areas represent utilization of habitat types and temporal
periods and dark gray areas indicate peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Holding
Adult Migration
Spawning1
Incubation
Fry Emergence
Juvenile Migration
Juvenile Rearing
Notes:
1 Longnose sucker typically spawn in spring, however, a second unconfirmed spawn period may occur during the late summer in Oct ober or November.
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Table 5.1-12. Periodicity of Dolly Varden in the Susitna River by life history stage and habitat type. Shaded areas represent utilization of habitat types and temporal
periods and dark gray areas indicate peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Holding
Adult Migration
Spawning
Incubation
Fry Emergence
Juvenile Rearing
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Table 5.1-13. Periodicity of Bering cisco utilization among macro-habitat types in the Susitna River by life history stage. Shaded areas indicate timing of utilization by
macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Holding1
Adult Migration
Spawning
Incubation
Fry Emergence
Juvenile Migration2
Notes:
1 Adult Bering Cisco holding and feeding habitat use in the Susitna River is not known; it is possible these fish reside in mar ine areas until spawning.
2 Juvenile rearing is not represented here because Bering cisco fry migrate to marine nursery habitats soon after hatching.
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Table 5.1-14. Periodicity of eulachon utilization among macro-habitat types in the Susitna River by life history stage. Shaded areas indicate timing of utili zation by
macro-habitat type and dark gray areas represent areas and timing of peak use.
Life Stage
Habitat Type
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Main Channel Side Channel Tributary Mouth Side Slough Upland Slough Tributary Adult Migration
Spawning
Incubation
Juvenile Migration1
Notes:
1 Juvenile rearing is not represented here because eulachon larvae migrate soon after hatching to estuar ine nursery habitats to rear.
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Table 6.1-1. Species, lifestages, and habitat parameters for which HSC curves have been developed for the Middle (M)
and Lower (L) Susitna River.
Species Life Stage Depth Velocity Substrate Cover
Chum Salmon Spawning M M MU
Juvenile M,L M,L M,L
Sockeye Salmon Spawning M M MU
Juvenile M,L M,L M,L
Chinook Salmon Spawning M M M
Juvenile M,L M,L M,L
Coho Salmon Spawning M M M
Juvenile M,L M,L M,L
Pink Salmon Spawning M M M
Rainbow Trout Adult M M M
Arctic Grayling Adult M M M
Round Whitefish Adult M M M
Juvenile M M M
Longnose Sucker Adult M M M
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Table 6.1-2. Substrate codes used in the development of HSC curves for the Susitna River during studies in the 1980s
(Vincent-Lang et al. 1984a, 1984b) and for three Bristol Bay drainages (North/South Fork Koktuli Rivers and Upper
Talarik Creek; PLP 2011).
Basin Literature
Code1
Adjusted
Code1 Substrate Size
(inches)
Size
(mm)
Susitna River
(Vincent-Lang et al. 1984a,
1984b)
1 1 Silt NA NA
2 1.5 Silt/Sand NA NA
3 2 Sand NA NA
4 2.5 Sand/Small Gravel NA NA
5 3 Small Gravel 1/8-1 0.125-25
6 4 Small Gravel/Large Gravel NA NA
7 5 Large Gravel 1-3 25-76
8 5.5 Large Gravel/Rubble NA NA
9 6 Rubble 3-5 76-127
10 6.5 Rubble/Cobble NA NA
11 7 Cobble 5-10 127-254
12 7.5 Cobble/Boulder NA NA
13 8 Boulder >10 >254
North/South Fork Koktuli
Rivers and Upper Talarik
Creek
(PLP 2011)
1 0 Vegetation NA NA
1.99 0.99 Vegetation NA NA
2 1 Fines <1/16 <2
2.99 1.99 Fines <1/16 <2
3 3 Small Gravel 1/16-3/4 2-16
3.99 3.99 Small Gravel 1/16-3/4 2-16
4 5 Large Gravel 3/4-2.5 16-64
4.99 5.99 Large Gravel 3/4-2.5 16-64
5 6 Small Cobble 2.5-5 64-128
5.99 6.99 Small Cobble 2.5-5 64-128
6 7 Large Cobble 5-10 128-256
6.99 7.99 Large Cobble 5-10 128-256
7 8 Boulder >10 >256
Notes:
1 “Literature codes” were standardized for comparability purposes by assigning “adjusted codes” used to
present substrate information in this document.
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Table 6.1-3. Number of salmon redds observed in spawning HSC data collection efforts in the Middle Segment Susitna
River during 1982-1983 studies.
Species Location HRM Habitat Type # Redds
Chum Slough 8A 125.3 Slough 52
Slough 9 126.3 Slough 76
Fourth of July Creek 131.0 Tributary Mouth 28
Slough 9A 133.3 Slough 24
Slough 11 135.3 Slough 34
Upper Side Channel 11 136.2 Side Channel 2
Indian River 138.6 Tributary Mouth 3
Slough 17 138.9 Slough 6
Slough 20 140.1 Slough 11
Side Channel 21 140.6 Side Channel 2
Slough 21 141.1 Slough 83
Slough 22 144.3 Slough 12
Sockeye Slough 8A 125.3 Slough 17
Slough 11 135.3 Slough 42
Slough 17 138.9 Slough 2
Slough 21 141.1 Slough 20
Chinook Fourth of July Creek 131.0 Tributary 1
Indian River 138.6 Tributary 125
Portage Creek 148.9 Tributary 137
Chechako Creek 152.5 Tributary 2
Table 6.1-4. Sampling effort (number of cells sampled) and juvenile salmon catch (all age classes) by gear type in the
Middle Susitna River during 1981-1982 studies (Suchanek et al. 1984b)
Species Electrofishing Beach Seining Total
Effort Catch Effort Catch Effort Catch
Chinook 871 3066 389 1329 1260 4395
Coho 871 1907 389 113 1260 2020
Sockeye1 658 814 355 192 1013 1006
Chum2 408 1152 106 5 514 1157
Notes:
2 Cells removed from consideration if located in tributaries without major runs or sampled when only a small
percentage of sockeye had emerged.
3 Cells removed from consideration if sampled after period of peak chum outmigration.
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Table 6.1-5. Cover type and percent cover habitat suitability criteria for juvenile salmon in the Middle Susitna River
(Suchanek et al. 1984b).
Cover Type Code Percent Cover Chinook
(clear)
Chinook
(turbid) Chum Coho Sockeye
No cover 1.1 0-5% 0.01 0.45 0.29 0.00 0.11
Emergent vegetation 2.1 0-5% 0.01 0.57 0.29 0.03 0.18
2.5 76-100% 0.12 1.00 0.53 0.29 0.47
Aquatic vegetation 3.1 0-5% 0.07 0.57 0.29 0.07 0.39
3.5 76-100% 0.68 1.00 0.53 0.65 1.00
Debris/deadfall 4.1 0-5% 0.11 0.57 0.47 0.10 0.19
4.5 76-100% 1.00 1.00 0.87 0.90 0.49
Overhanging riparian
vegetation
5.1 0-5% 0.06 0.57 0.40 0.04 0.30
5.5 76-100% 0.61 1.00 0.74 0.38 0.78
Undercut banks 6.1 0-5% 0.10 0.57 0.40 0.12 0.11
6.5 76-100% 0.97 1.00 0.74 1.00 0.29
Large gravel (1-3") 7.1 0-5% 0.07 0.57 0.37 0.03 0.17
7.5 76-100% 0.63 1.00 0.68 0.24 0.44
Rubble (3-5") 8.1 0-5% 0.09 0.57 0.54 0.02 0.12
8.5 76-100% 0.81 1.00 1.00 0.18 0.30
Cobble or boulder
(>5")
9.1 0-5% 0.09 0.57 0.46 0.02 0.11
9.5 76-100% 0.89 1.00 0.86 0.18 0.29
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Table 6.1-6. Cover type and percent cover habitat suitability criteria for juvenile salmon in the Lower Susitna River
(Suchanek et al. 1985).
Cover Type Code Percent Cover Chinook
(clear)
Chinook
(turbid) Chum Coho Sockeye
No cover 1.1 0-5% 0.01 0.15 1.00 0.00 0.18
Emergent vegetation
2.1 0-5% 0.11 0.23 1.00 0.05 0.39
2.2 6-25% 0.33 0.30 1.00 0.14 0.54
2.3 26-50% 0.55 0.33 1.00 0.24 0.70
2.4 51-75% 0.78 0.39 1.00 0.33 0.85
2.5 76-100% 1.00 0.40 1.00 0.42 1.00
Aquatic vegetation
3.1 0-5% 0.10 0.23 1.00 0.04 0.23
3.2 6-25% 0.32 0.30 1.00 0.13 0.32
3.3 26-50% 0.53 0.33 1.00 0.21 0.41
3.4 51-75% 0.76 0.39 1.00 0.30 0.50
3.5 76-100% 0.97 0.40 1.00 0.38 0.59
Debris/deadfall
4.1 0-5% 0.05 0.15 1.00 0.08 0.21
4.2 6-25% 0.17 0.20 1.00 0.24 0.29
4.3 26-50% 0.28 0.20 1.00 0.39 0.37
4.4 51-75% 0.39 0.20 1.00 0.55 0.45
4.5 76-100% 0.50 0.20 1.00 0.70 0.53
Overhanging riparian
vegetation
5.1 0-5% 0.04 0.15 1.00 0.07 0.25
5.2 6-25% 0.13 0.20 1.00 0.20 0.34
5.3 26-50% 0.21 0.20 1.00 0.33 0.44
5.4 51-75% 0.30 0.20 1.00 0.46 0.54
5.5 76-100% 0.38 0.20 1.00 0.59 0.63
Undercut banks
6.1 0-5% 0.11 0.23 1.00 0.12 0.25
6.2 6-25% 0.33 0.30 1.00 0.34 0.34
6.3 26-50% 0.55 0.33 1.00 0.56 0.44
6.4 51-75% 0.78 0.39 1.00 0.78 0.54
6.5 76-100% 1.00 0.40 1.00 1.00 0.63
Large gravel (1-3")
7.1 0-5% 0.02 0.15 1.00 0.02 0.18
7.2 6-25% 0.08 0.20 1.00 0.06 0.24
7.3 26-50% 0.13 0.20 1.00 0.10 0.32
7.4 51-75% 0.18 0.20 1.00 0.14 0.38
7.5 76-100% 0.23 0.20 1.00 0.18 0.45
Rubble (3-5")
8.1 0-5% 0.03 0.15 1.00 0.02 0.18
8.2 6-25% 0.10 0.20 1.00 0.06 0.24
8.3 26-50% 0.17 0.20 1.00 0.10 0.32
8.4 51-75% 0.23 0.20 1.00 0.14 0.38
8.5 76-100% 0.30 0.20 1.00 0.18 0.45
Cobble or boulder
(>5")
9.1 0-5% 0.03 0.15 1.00 0.02 0.18
9.2 6-25% 0.11 0.20 1.00 0.06 0.24
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Cover Type Code Percent Cover Chinook
(clear)
Chinook
(turbid) Chum Coho Sockeye
9.3 26-50% 0.18 0.20 1.00 0.10 0.32
9.4 51-75% 0.25 0.20 1.00 0.14 0.38
9.5 76-100% 0.32 0.20 1.00 0.18 0.45
Table 6.1-7. Adult resident fish catch by gear type in the Middle Segment Susitna River during 1981-1982 studies
(Suchanek et al. 1984b). Sampling effort involved boat electrofishing in 176 cells and hook-and-line sampling in 79 cells.
Species Boat Electrofishing Hook and Line
Rainbow trout 44 99
Arctic grayling 138 2
Round whitefish 384
Longnose sucker 157
Burbot 18
Humpback whitefish 15
Dolly Varden 2
Table 6.1-8. Cover type habitat suitability criteria for resident fish in the Middle Susitna River (Suchanek et al. 1984b).
Cover Type Code
Rainbow Trout
(Adult)
Arctic Grayling
(Adult)
Round
Whitefish
(Adult)
Round
Whitefish
(Juvenile)
Longnose
Sucker
(Adult)
Clear Turbid Clear Turbid Clear Turbid Clear Turbid Clear Turbid
No cover 1 0.00 0.29 0.00 0.07 0.00 0.26 0.00 1.00 0.00 0.47
Emergent
vegetation 2 0.00 0.29 0.00 0.07 0.47 0.47 0.00 1.00 1.00 1.00
Aquatic
vegetation 3 0.00 0.29 0.00 0.07 0.47 0.47 0.00 1.00 1.00 1.00
Debris/deadfall 4 1.00 1.00 0.14 0.14 0.65 0.65 0.00 1.00 0.46 0.47
Overhanging
riparian
vegetation
5 1.00 1.00 0.14 0.14 0.65 0.65 0.00 1.00 0.46 0.47
Undercut banks 6 1.00 1.00 0.14 0.14 0.65 0.65 0.00 1.00 0.46 0.47
Large gravel (1-
3") 7 0.00 0.29 0.00 0.07 0.33 0.33 0.00 1.00 0.00 0.47
Rubble (3-5") 8 0.77 0.77 0.69 0.69 0.41 0.41 0.00 1.00 0.00 0.47
Cobble or boulder
(>5") 9 1.00 1.00 1.00 1.00 1.00 1.00 0.00 1.00 0.00 0.47
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Table 6.3-1. Summary of the proposed target species and life stages, macro-habitat types, sample sites, potential sampling techniques, and sampling timing applied
during 2012 HSC curve validation surveys.
Species Life Stage River Segment
Macro-Habitat
Areas1 Sample Sites1
Possible Sampling
Technique Sample Timing1
Chinook
Juvenile Middle River Slough, side channel,
tributary mouths Slough 21, 8A, and 6A Snorkel, electrofishing,
seining June, July, August, September
Spawning Middle River Tributary, mainstem Indian R., 4th of July
Cr., Lane Cr.
Pedestrian survey, side
scan sonar, DIDSON July, August
Sockeye
Juvenile Middle River Slough, side channel,
tributary mouths Slough 20, 9, 8, 6A Snorkel, electrofishing,
seining June, July, August, September
Spawning Middle River Slough, and side
channels Slough 11, 8A, Pedestrian survey, side
scan sonar, DIDSON August, September, October
Coho
Juvenile Middle River Slough, side channel,
tributary mouths
Slough 6A, Lane Cr.,
Birch & Sunshine Cr.
Snorkel, electrofishing,
seining June, July, August, September
Spawning Middle River Tributary mouths Indian R., 4th of July
Cr., Slough 8A Pedestrian survey August, September
Chum
Juvenile Middle River Slough, side channel,
tributary mouths Slough 21, 9, and 6A Snorkel, electrofishing,
seining June, July, August,
Spawning Middle River Slough, side channel,
mainstem Slough 21, 11, and 8A Pedestrian survey, side
scan sonar, DIDSON August, September
Pink
Juvenile Middle River Slough, side channel,
tributary mouths None specified Snorkel, electrofishing,
seining June, July
Spawning Middle River Slough, side channel,
tributary mouths Slough 21, 15, and 11 Pedestrian survey July, August
Notes:
1 ADF&G 1983 – Synopsis of the 1982 Aquatic Studies and Analysis of Fish and Habitat Relationships
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Table 6.3-2. Site-specific habitat suitability measurements recorded during 2012 at Middle and Lower Susitna River
sampling sites, by fish life stage.
Susitna River
Segment
River
Mile Site Name Habitat Type
Fish Life
Stage
Number of
Observations
Middle 178.3 178.3R Side Channel
Fry 6
Juvenile 4
Adult 5
Middle 176.6 Fog Creek mouth Tributary Mouth Fry 4
Adult 1
Middle 174.2 174.2L Mainstem N/A 0
Middle 144.4 Slough 22 Side Slough Fry 5
Adult 1
Middle 141.8 Slough 21 Side Slough N/A 0
Middle 141.2 Side Channel 21 Side Channel Fry 9
Adult 7
Middle 138.6 Indian River Mouth Tributary Mouth Fry 11
Adult 8
Middle 135.6 Slough 11 Side Slough Adult 8
Middle 133.9 Slough 10 Upland Slough N/A 0
Middle 133.7 Slough 9A Side Slough Adult 19
Middle 131.2 Unnamed Side Channel Side Channel Adult 11
Middle 131.1 4th of July Creek Mouth Tributary Mouth Fry 3
Adult 8
Middle 128.8 Slough 9 Side Slough Adult 15
Middle 125.3 Skull Creek Side Slough Adult 26
Middle 122.5 Slough 8B Side Slough N/A 0
Middle 121.0 Tulips Creek mouth Tributary Mouth N/A 0
Middle 115.0 115.0R Side Channel Fry 2
Middle 113.7 Slough 8 Side Slough Fry 4
Juvenile 1
Middle 113.6 Lane Cr Mouth Tributary Mouth Fry 2
Adult 1
Middle 112.5 Slough 6A Upland Slough Fry 15
Middle 101.4 Whiskers Slough Side Slough Fry 13
Adult 3
Middle 101.4 Whiskers Creek Mouth Tributary Mouth Fry 12
Lower 95.4 Cache Creek slough Side Slough Fry 6
Juvenile 1
Lower 95.4 Unnamed Side Channel Side Channel Fry 4
Juvenile 1
Lower 93.5 Unnamed Side Channel Side Channel Fry 4
Juvenile 1
Lower 91.6 Trapper Creek Side Channel Side Channel Fry 12
Juvenile 4
Lower 91.5 Trapper Creek Tributary Mouth Fry 4
Lower 91.5 Birch Slough Side Slough Fry 2
89.2 Birch Slough Side Slough Fry 1
Lower 85.2 Sunshine Creek Side Channel Side Channel Fry 13
Juvenile 3
Lower 85.1 Sunshine Creek Tributary Mouth Fry 18
Lower 83.1 Rabideux Creek Tributary Mouth N/A 0
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Susitna River
Segment
River
Mile Site Name Habitat Type
Fish Life
Stage
Number of
Observations
Lower 77.0 Montana Creek Tributary Mouth Adult 7
Side Channel Adult 10
Table 6.3-3. Proposed substrate classification system for use in development of HSC/HSI curves for the Susitna -Watana
Project (adapted from Wentworth 1922).
Substrate Code Substrate Type Size (Decimal Inches) Size (mm)
1 Silt, Clay, or Organic <0.01 <0.1
2 Sand 0.01-0.10 0.1-2.0
3 Small Gravel 0.10-0.30 2.0-8.0
4 Medium Gravel 0.30-1.25 8.0-32
5 Large Gravel 1.25-2.50 32-64
6 Small Cobble 2.50-5.0 64-128
7 Large Cobble 5.0-10.0 128-256
8 Boulder >10.0 >256
9 Bedrock
Table 6.3-4. Number of spawning redds sampled by river reach and macrohabitat type during HSC surveys of the
Susitna River, Alaska (combined R2 and LGL datasets).
Macrohabitat Type
River Salmon Species
Segment Chinook Sockeye Pink Chum Coho
Sloughs
Slough 21 Middle 0 0 0 7 0
Slough 11 Middle 0 4 0 4 0
4th of July Slough Middle 0 0 0 11 0
Slough 10 Middle 0 0 0 0 0
Slough 9A Middle 0 4 0 19 0
Slough 9 Middle 0 14 0 1 0
Slough 8a Middle 0 21 0 1 0
Whiskers Slough Middle 0 0 3 0 0
Tributary Delta
Indian River Middle 0 0 0 3 0
4th of July Cr. Middle 0 0 7 1 0
Montana Cr. Lower 0 0 7 0
Side Channel
Montana Cr. Lower 0 0 0 10 0
Total 0 43 17 57 0
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Table 6.3-5. Number of HSC made within each of the major macrohabitat types for each target species and life stage
during the 2012 HSC surveys of the Susitna River, Alaska.
Species & Life Stage
Number of HSC Observations by Macrohabitat Type
MC SC SS T. Delta
Chinook
Juvenile 0 3 4 4
Fry 1 15 8 7
Sockeye
Spawning 0 0 43 0
Fry 0 5 0 1
Pink
Spawning 0 0 3 14
Chum
Spawning 0 10 43 4
Fry 3 3 2
Coho
Juvenile 0 8 3 8
fry 3 6 24 20
Arctic Grayling
Adult 1 3 0 4
Juvenile 0 1 0 0
Fry 1 3 4 2
Rainbow Trout
Adult 0 0 1 6
Juvenile 0 0 1 0
Fry 0 0 0 1
Whitefish
Juvenile 0 3 3 1
Fry 0 2 0 0
Longnose Sucker
Adult 0 1 0 0
Juvenile 0 0 1 0
Total 6 63 141 74
Percent of Total 2% 22% 50% 26%
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Table 6.3-6. Number of HSC observations made within each of the major macrohabitat types for each target species and
life stage during the 2012 HSC surveys of the Susitna River, Alaska.
Species & Life Stage
Number and Percent of HSC Observations by 2012 Survey Date
July (17-19) Aug (21-23) Sep (17-19) Total Obs.
Chinook
Juvenile 11 (100%) 11
Fry 13 (41.9%) 10 (32.3%) 8 (25.8%) 31
Sockeye
Spawning 11 (25.6%) 32 (74.4%) 43
Fry 6 (100%) 6
Pink
Spawning 17 (100%) 17
Chum
Spawning 56 (98.2%) 1 (1.8%) 57
Fry 3 (37.5%) 5 (62.5%) 8
Coho
Juvenile 5 (26.3%) 14 (73.7%) 19
Fry 44 (83%) 8 (15.1%) 1 (1.9%) 53
Arctic Grayling
Adult 4 (50%) 4 (50%) 8
Juvenile 1 (100%) 1
Fry 1 (10%) 4 (40%) 5 (50%) 10
Rainbow Trout
Adult 7 (100%) 7
Juvenile 1 (100%) 1
Fry 1 (100%) 1
Whitefish
Juvenile 5 (71.4%) 2 (28.6%) 7
Fry 2 (100%) 2
Longnose Sucker
Adult 1 (100%) 1
Juvenile 1 (100%) 1
Total/Percent of Total 78/27.5% 152/53.5% 54/19% 284
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Table 6.3-7. Periodicity of Pacific salmon habitat utilization in the Middle Segment (RM 184-98.5) of the Susitna River by species and life history stage. Shaded areas
indicate timing of utilization and dark gray areas represent peak use.
Species Life Stage Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Chinook
Salmon
Adult Migration
Spawning
Incubation
Fry Emergence
Rearing (0+)
Rearing (1+)
Juvenile Migration
(0+)
Juvenile Migration
(1+)
Chum
Salmon
Adult Migration
Spawning
Incubation
Fry Emergence
Rearing (0+)
Juvenile Migration
(0+)
Coho
Salmon
Adult Migration
Spawning
Incubation
Fry Emergence
Rearing (0+)
Rearing (1+)
Rearing (2+)
Juvenile Migration
(0+)
Juvenile Migration
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Species Life Stage Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
(1+)
Juvenile Migration
(2+)
Sockeye
Salmon1
Adult Migration1
Spawning1
Incubation
Fry Emergence
Rearing (0+)
Rearing (1+)
Juvenile Migration
(0+)
Juvenile Migration
(1+)
Pink
Salmon2
Adult Migration
Spawning
Incubation
Fry Emergence
Juvenile Migration
(0+)
Notes:
1 First-run and second-run sockeye salmon exhibit distinct timing of adult migration and spawning, and utilize separate areas for spawning. Periodi city
presented here represent that of second-run sockeye, as first-run sockeye do not utilize the Middle Susitna River.
2 No rearing period for age 0+ pink salmon is identified because this species migrates to the estuary soon after emergence.
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Table 7.1-1. Instream flow sites and habitat modeling methods used during the 1980s in the Middle and Lower Susitna
River (Marshall et al. 1984; Sandone et al. 1984; Vincent-Lang et al. 1984b; Hilliard et al. 1985; Suchanek et al. 1985).
River
Mile Site Name
Susitna
Segment Habitat Type Site Type
No. of
Transects
Year(s)
Measured
35.2 Hooligan Side Channel Lower Side Channel RJHAB 5 1984
36.2 Eagles Nest Side Channel Lower Side Channel RJHAB 4 1984
36.3 Kroto Slough Head Lower Side Slough RJHAB 5 1984
39.0 Rolly Creek Mouth Lower Tributary Mouth RJHAB 6 1984
42.9 Bear Bait Side Channel Lower Side Channel RJHAB 5 1984
44.4 Last Chance Creek Side Channel Lower Side Channel RJHAB 6 1984
59.5 Rustic Wilderness Side Channel Lower Side Channel RJHAB 5 1984
63.0 Caswell Creek Lower Tributary Mouth RJHAB 8 1984
63.2 Island Side Channel Lower Side Channel IFG-4, RJHAB 9 1984
74.4 Mainstem West Bank Lower Side Slough IFG-4 7 1984
74.8 Goose 2 Side Channel Lower Side Channel RJHAB 6 1984
75.3 Circular Side Channel Lower Side Channel IFG-4 6 1984
79.8 Sauna side channel Lower Side Channel IFG-4 4 1984
84.5 Sucker side channel Lower Side Channel RJHAB 6 1984
86.3 Beaver Dam side channel Lower Side Channel RJHAB 5 1984
86.3 Beaver Dam Slough Lower Side Slough RJHAB 5 1984
86.9 Sunset side channel Lower Side Channel IFG-4 7 1984
87.0 Sunrise side channel Lower Side Channel RJHAB 7 1984
88.4 Birch Slough Lower Side Slough RJHAB 8 1984
91.6 Trapper Creek side channel Lower Side Channel IFG-4, RJHAB 5 1984
101.2 101.2 R, Whiskers East Middle Side Channel IFG-4 9 1984
101.4 Whiskers Slough Middle Side Slough RJHAB 8 1983
101.5 101.5 L, Whiskers West Middle Side Channel IFG-2 5 1984
101.7 101.7 L Middle Side Channel DIHAB 4 1984
105.8 105.8 L Middle Mainstem DIHAB 4 1984
107.6 Slough 5 Middle Upland Slough RJHAB 9 1983
112.5 Slough 6A Middle Upland Slough RJHAB 8 1983
112.6 112.6 L, Side Channel 6A Middle Side Channel IFG-2 9 1984
113.6 Lane Creek mouth Middle Tributary Mouth
Habitat
Mapping 7 1983
113.7 Slough 8 Middle Side Slough RJHAB 5 1983
114.1 114.1 R Middle Side Channel DIHAB 3 1984
115.0 115.0 R Middle Side Channel DIHAB 4 1984
118.9 118.9 L Middle Mainstem DIHAB 3 1984
119.1 119.1 L Middle Mainstem DIHAB 3 1984
119.2 119.2 R, Little Rock side channel Middle Side Channel IFG-2 5 1984
125.2 125.2 R Middle Side Channel DIHAB 2 1984
125.3 Skull Creek Middle Side Slough IFG-4 11 1983
128.8 Slough 9 Middle Side Slough IFG-4 10 1983
130.2 130.2 R Middle Side Channel DIHAB 3 1984
131.1 4th of July Creek mouth Middle Tributary Mouth
Habitat
Mapping 8 1983
131.3 131.3 L Middle Side Channel DIHAB 4 1984
131.7 131.7 L Middle Side Channel IFG-4 7 1984
132.6 132.6 L, Side channel 10A Middle Side Channel IFG-4, RJHAB 9 1983-1984
133.8 133.8 R Middle Mainstem DIHAB 3 1984
133.8 Side channel 10 Middle Side Channel IFG-4 4 1983
134.9 Lower Side channel 11 Middle Side Channel IFG-2 6 1983
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River
Mile Site Name
Susitna
Segment Habitat Type Site Type
No. of
Transects
Year(s)
Measured
136.0 136.0 L, Slough 14 Middle Side Channel IFG-4 6 1984
136.3 Upper Side channel 11 Middle Side Channel IFG-4 4 1983
137.5 137.5 R Middle Side Channel DIHAB 3 1984
138.7 138.7 L Middle Mainstem DIHAB 3 1984
139.0 139.0 L Middle Mainstem DIHAB 4 1984
139.4 139.4 L Middle Side Channel DIHAB 3 1984
141.2 Side channel 21 Middle Side Channel IFG-4 5 1983
141.8 Slough 21 Middle Side Slough IFG-4 5 1983
144.4 Slough 22 Middle Side Slough RJHAB 8 1983
147.1 147.1 L, Fat Canoe SC Middle Side Channel IFG-2 6 1984
Table 7.1-2. Representative Groups used as part of the methodology to extrapolate results from modeled to non-modeled
areas in the Middle Susitna River during 1980s studies. Source: Aaserude et al. (1985).
Extrapolation for Single-Thread River System (IFIM)
Extrapolation for Multiple-Thread River System
(Aaserude et al. 1985)
Proportional length basis Proportional area basis
Continuous segments Discontinuous segments termed ‘Representative Groups’
Intensively studied representative reaches Intensively studied representative reaches plus general
reconnaissance level survey of entire river system
Extrapolation from representative reaches to associated
subsegments without adjustment
Extrapolation from representative reaches to associated
representative groups with adjustment to account for
inequalities in structural habitat between specific areas
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Table 7.1-3. Representative Groups used as part of the methodology to extrapolate results from modeled to non-modeled
areas in the Middle Susitna River during 1980s studies. Source: Aaserude et al. (1985).
Representative
Group Description
Group I Predominantly upland sloughs. Areas are highly stable due to persistence of non-breached conditions.
Area hydraulics characterized by pooled clear water with velocities frequently near 0 fps and depths > 1 ft.
Pools commonly connected by short riffles with velocities < 1 fps and depths < 0.5 ft.
Group II Side sloughs that are characterized by relatively high breaching flows (>19,500 cfs), clear water caused by
upwelling groundwater and large channel length to width ratios (> 15:1).
Group III Areas with intermediate breaching flows and relatively broad channel sections. These areas consist of
side channels which transform into side sloughs at mainstem discharges ranging from 8,200 to 16,000 cfs.
These areas are distinguishable from Group II by lower breaching flows and smaller length to width ratios.
Upwelling water is present.
Group IV Side channels that are breached at low flows and possess intermediate mean velocities (2–5 fps) at a
mainstem discharge of approximately 10,000 cfs.
Group V Mainstem and side shoal areas that transform to clear water side sloughs as mainstem flows recede.
Transformations generally occur at moderate to high breaching flows.
Group VI Similar to Group V. Sites within this group are primarily overflow channels that parallel the adjacent
mainstem, usually separated by sparsely vegetated gravel bar. Upwelling may or may not be present.
Habitat transformations within this group are variable in type and timing.
Group VII Side channels that breach at variable yet fairly low mainstem discharges and exhibit characteristic
riffle/pool sequence. Pools are frequently large backwater areas near the mouth of the sites.
Group VIII Area that dewater at relatively high flows. Flow direction at the head of the channels tends to deviate
sharply (> 30 degrees) from the adjacent mainstem.
Group IX Secondary mainstem channels that are similar to the primary mainstem channels in habitat character, but
distinguished as being smaller and conveying a lesser proportion of the total discharge. Areas within this
group have low breaching discharges and are frequently similar in size to large side channels, but have
characteristic mainstem features, such as relatively swift velocities (> 5fps) and coarser substrate.
Group X Large mainstem shoals and margins of mainstem channels that show signs of upwelling.
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Table 7.2-1. Assessment of physical and biological processes and potential habitat modeling techniques.
Physical and
Biological Processes
Habitat Types
Mainstem Side Channel Slough
Tributary
Mouths
Spawning PHAB/VZM PHAB PHAB/HabMap PHAB/RFR
Incubation RFR/VZM PHAB PHAB/HabMap PHAB/RFR
Juvenile Rearing PHAB/RFR PHAB PHAB/HabMap PHAB/RFR
Adult Holding RFR RFR PHAB/HabMap PHAB/RFR
Macroinvertebrates VZM/WP VZM/WP PHAB/HabMap/WP N/A
Standing/Trapping VZM VZM VZM/WP VZM/WP
Upwelling/Downwelling FLIR HabMap/FLIR HabMap/FLIR HabMap/FLIR
Temperature WQ WQ WQ WQ
Ice Formation IceProcesses/WQ/RFR IceProcesses/WQ/RFR HabMap/Open leads N/A
Notes:
1 PHAB-Physical Habitat Simulation Modeling (1-D, 2-D, and empirical); VZM-Effective Spawning and
Incubation/Varial Zone Modeling; RFR-River Flow Routing Modeling; FLIR – Forward-looking Infrared
Imaging; HabMap-Surface Area Mapping; WQ-Water Quality Modeling; WP-Wetted Perimeter Modeling.
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Table 7.2-2. Conceptual Comparison of Multiple Resource Indicators of the Effects of Alternative Operational Scenarios
for the Susitna-Watana Hydroelectric Project. Indicators to be coordinated with resource-specific working groups.
(Indicators provided for illustration purposes only)
Existing
Conditions
(EC-01)
Scenario 1
(Ver. 1/20/15)
(OS-01)
Scenario 2
(Ver. 02/14/15)
(OS-02)
Scenario 3
(Ver. 02/14/15)
(OS-03) Run Description Average monthly MIF(cfs)
Max generation Nov-Mar (cfs)
Min generation Nov-Mar (cfs)
Max generation Apr-Oct (cfs)
Min generation Apr-Oct (cfs)
Ramping Rates
Evaluation Indicators Power Weighted average generation Nov-Mar (MWh)
Weighted average generation Apr-Oct (MWh)
Weighted annual dependable capacity (MWh) Hydrologic Max 1-day flow (cfs) wet / avg /dry wet / avg / dry wet / avg / dry wet / avg / dry wet / avg / dry
Min 2-day low, Nov-Mar (cfs)
Min 2-day low Jul-May as % of 2-day max Jul-Sep
Freshets (Apr-Jun) [Qc]>1.5*[QC-1+QC-2+QC-3]/3
Water Particle Travel Time, 25% exceedance, Apr-
Jun
Other IHA statistics Reservoir Average reservoir volume (KAF) wet / avg /dry
wet / avg / dry wet / avg / dry wet / avg / dry
Min 2-day reservoir volume (KAF)
Weighted annual euphotic zone (KAF)
Other Biological/recreation indicators Ramping Weighted avg annual total, Middle Susitna, reach-
averaged (ra) downramping events >1-inch pr
hour
Weighted average annual total, Middle Susitna,
reach-averaged downramping events > 2-inch per
hour
Weighted average annual total, Middle Susitna,
reach-averaged downramping events > 4-inches per
hour
Varial Zone Median annual, MS, reach-averaged (ra) channel
width-ft
Total varial zone, MS, 12-hr/12-hr, ra, median
annual channel width-ft
Total varial zone, MS, 12-hr/7-day, ra, median
annual channel width-ft
Total varial zone, MS, 12-hr/30-day, ra, median
annual channel width-ft
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Evaluation Indicators
(Indicators provided for illustration purposes only)
Existing
Conditions
(EC-01)
Scenario 1
(Ver. 1/20/15)
(OS-01)
Scenario 2
(Ver. 02/14/15)
(OS-02)
Scenario 3
(Ver. 02/14/15)
(OS-03) Potential Salmon Habitat Chum spawning habitat, Devils Canyon to 3 Rivers
(DCto3R) reach-averaged(ra), gross channel
width, (ft)
Chum effective spawning/incubation, DCto3R-
reach-averaged (ra), channel width accounting for
dewatering, groundwater/surface water interactions,
water quality effects, net width (ft)
Coho effective spawning/incubation, DCto3R-ra, net
width, (ft)
Sockeye effective spawning and incubation,
DCto3R-ra, slough/side channel, net width (ft)
Pink effective spawning/incubation, DCto3R-ra,
slough/side channel, net width (ft)
Coho juvenile habitat, open-water, DCto3R-ra,
channel width (ft)
Coho juvenile habitat, ice-period, DCto3R-ra,
channel width (ft)
Chinook juvenile habitat, ice-period, DCto3R-ra,
slough/side channel width (ft) Other Fish Grayling average minimum spawning, Watana Dam
to Devils Canyon (DtoDC), reach averaged WUA,
(ft2)
Northern pike effective spawning and incubation,
DCto3R-reach averaged slough/side channel net
width (ft)
Riparian Wet meadow area, reach averaged, DC to3R, post-
licensing yrs 10-20 (acres)
Scrub thickets, reach averaged, DC to 3R, post-
licensing yrs 10-20 (acres)
Floodplain plant community colonization area, reach
averaged, DC to 3R, post-licensing yrs 10-20
(acres)
Other riparian indicators Recreation Devils Canyon to 3R, tour boat accessible, May to
Sep (days)
Three Rivers to Sunshine, days channel exceeds
minimum boating depth, May to Sep
Devils Canyon to 3 R, upstream extent of January
ice cover for snow machine travel
Other recreation/access indicators Other Aquatics Other potential indicators of Project effects such as:
▫ minimum slough area,
▫ percent of river length mobilized-D25
▫ downstream extent of ice-free zone,
▫ 30-day wetted euphotic streambed,
▫ other reaches, seasons, life stages, mesohabitats
to be determined in consultation with TWG
Notes:
1. Average of five select years weighted by likelihood of occurrence (Dry Year* 0.077, Somewhat Dry Year* 0.231, Average Year *
0.462, Somewhat Wet Year * 0.115, Wet Year*0.115) (values are for illustration purposes only)
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Table 8.1-1. Description of habitat zones sampled at Designated Fish Habitat Sites: June through September 1982 (From
Estes and Schmidt 1983).
Zone Code Description
1 Areas with a tributary or ground water source which are not influenced by mainstem stage and which usually
have a significant1 surface water velocity.
2 Areas with a tributary or ground water source which have no appreciable1 surface water velocity as a result of a
hydraulic barrier created at the mouth of a tributary or slough by mainstem stage.
3 Areas of significant surface water velocities, primarily influenced by the mainstem, where tributary or slough
water mixes with the mainstem water.
4 Areas of significant water surface velocities which are located in a slough or side channel above a tributary
confluence (or in a slough where no tributary is present) when the slough head is open.
5 Areas of significant water surface velocities which are located in at slough or side channel below a tributary
confluence when the slough head is open.
6
Backwater areas with no appreciable surface water velocities which result from a hydraulic barrier created by
mainstem stage which occur in a slough or side channel above a tributary confluence (or in a slough or side
channel where no tributary is present), when the head of the slough is open.
7
Backwater areas with no appreciable surface water velocities which result from a hydraulic barrier created by
mainstem stage which occur in a slough or side channel below a tributary confluence, when the head of the
slough is open.
8 Backwater areas consisting of mainstem eddies.
9 A pool with no appreciable surface water surface velocities which is created by a geomorphological feature of a
free-flowing zone or from a hydraulic barrier created by a tributary; not created as a result of mainstem stage.
Notes:
1 “Significant” and “appreciable” surface water velocities mean a velocity of at least 0.5 ft/sec. However, there
are site-specific exceptions to this, based on local morphology.
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Table 8.1-2. Aggregate Hydraulic (H), Water Source (W) and Velocity (V) zones. Source: Estes and Schmidt (1983),
Schmidt et al. (1983).
Aggregate Zone Habitat Zone Included Definition
H-I 1, 4, 5, 9 not backed up by mainstem
H-II 2, 6, 7, 8 backed up by mainstem
H-III 3 mainstem
W-I 1, 2 tributary water and/or ground water only
W-II 4, 6, 8, sometimes 3 mainstem water only
W-III 5, 7, sometimes 3 mixed water sources
V-I1 1, 3, 4, 5 Fast water
V-II1 2, 6, 7, 8, 9 Slow water
Notes:
1 The habitat zones included in aggregate zones V-I and V-II were not provided in the source documents. Zone
descriptions were used to classify which zones were fast and slow water.
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11. FIGURES
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Figure 3.1-1. Habitat types identified in the middle reach of the Susitna River during the 1980s studies (adapted from
ADF&G 1983b; Trihey 1982).
Side
Slough
Upland
Slough
Tributary Tributary
Mouth
Lake
Hyporheic
Zone
Side Channel
Mainstem
Channel
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Figure 3.1-2. Map of Designated Fish Habitat (DFH) sites sampled on the Susitna River, June through September 1982.
Source: Schmidt et al. (1983).
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Figure 3.1-3. Hypothetical slough with delineated habitat zones. Source: Estes and Schmidt (1983).
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Figure 3.1-4. Typical arrangement of transects, grids, and cells at a JAHS site. Source: Dugan et al. (1984).
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Figure 3.2-1. Map depicting the Upper, Middle and Lower Segments of the Susitna River potentially influenced by the Susitna-Watana Hydroelectric Project.
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Figure 3.3-1. Map of the Middle Segment of the Susitna River depicting the eight Geomorphic Reaches and locations of proposed Focus Areas. No Focus Areas are
proposed for in MR-3 and MR-4 due to safety issues related to sampling within or proximal to Devils Canyon.
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Figure 3.3-2. Map showing Focus Area 184 that begins at Project River Mile 184.7 and extends upstream to PRM 185.7. The Focus Area is located about 1.4 miles
downstream of the proposed Watana Dam site near Tsusena Creek.
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Figure 3.3-3. Map showing Focus Area 173 beginning at Project River Mile 173.6 and extends upstream to PRM 175.4. This Focus Area is near Stephan Lake and
consists of main channel and a side channel co mplex.
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Figure 3.3-4. Map showing Focus Area 171 beginning at Project River Mile 171.6 and extends upstream to PRM 173. This Focus Area is near Stephan Lake and
consists of main channel and a single side channel with vegetated island.
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Figure 3.3-5. Map showing Focus Area 151 beginning at Project River Mile 151.8 and extends upstream to PRM 152.3. This single main channel Focus Area is at the
Portage Creek confluence.
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Figure 3.3-6. Map showing Focus Area 144 beginning at Project River Mile 144.4 and extends upstream to PRM 145.7. This Focus Area is located about 2.3 miles
upstream of Indian River and includes Side Channel 21 and Slough 21.
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Figure 3.3-7. Map showing Focus Area 141 beginning at Project River Mile 141.8 and extends upstream to PRM 143.4. This Focus Area includes the Indian River
confluence and a range of main channel and off-channel habitats.
Slough 17
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Figure 3.3-8. Map showing Focus Area 138 beginning at Project River Mile 138.7 and extends upstream to PRM 140. This Focus Area is near Gold Creek and consists
of a complex of side channel, side slough and upland slough habitats including Upper Side Channel 11 and Slough 11.
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Figure 3.3-9. Map showing Focus Area 128 beginning at Project River Mile 128.1 and extends upstream to PRM 129.7. This Focus Area consists of side channel, side
slough and tributary confluence habitat features including Skull Creek.
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Figure 3.3-10. Map showing Focus Area 115 beginning at Project River Mile 115.3 and extends upstream to PRM 116.5. This Focus Area is located about 0.6 miles
downstream of Lane Creek and consists of side channel and upland slough habitats including Slough 6A.
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Figure 3.3-11. Map showing Focus Area 104 beginning at Project River Mile 104.8 and extends upstream to PRM 106. This Focus Area covers the diverse range of
habitats in the Whiskers Slough complex.
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Figure 3.3-12. Map showing proposed location of lower Susitna River instream flow -fish habitat transects in Geomorphic Reach LR-1 in the vicinity of Trapper Creek.
The proposed location, number, angle, and transect endpoints are tentative pending on-site confirmation during open-water conditions. Where feasible, instream flow
fish habitat transects will be co-located with geomorphology, open-water flow routing, and instream flow-riparian transects.
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Figure 3.3-13. Map showing proposed location of lower Susitna River instream flow -fish habitat transects in Geomorphic Reach LR-2 in the vicinity of Caswell Creek.
The proposed location, number, angle, and transect endpoints are tentative pending on-site confirmation during open-water conditions. Where feasible, instream flow
fish habitat transects will be co-located with geomorphology, open-water flow routing and instream flow -riparian transects.
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Figure 3.3-14. Map of the Lower Segment of the Susitna River depicting the six Geomorphic Reaches and locations of proposed 2013 study ar eas for geomorphology,
instream flow –fish, instream flow-riparian and fish distribution and abundance.
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Figure 4.2-1. Sampling effort at 225 mainstem Selected Fish Habitat sites during 1982. Data Source: Schmidt et al. (1983).
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Figure 4.3-1. Distribution of Chinook salmon in the Susitna River Basin from ADF&G’s Anadromous Waters Catalog.
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Figure 4.3-2. Catch per unit effort of Artic grayling by hook and line in tributaries to the upper Middle and Upper Susitna River during 1981 and 1982.The absence of a
line at zero indicates no sampling occurred at that site and period. Data Source: Delaney et al. (1981 c), Sautner and Stratton (1983).
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Figure 4.3-3. Total catch of burbot by trotlines during 1981 (top) at tributary mouths and CPUE of burbot at mainstem
sites in the Upper Susitna River during 1982 (bottom). Data Sources: Delaney et al. (1981c), Sautner and Stratton (1983).
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Figure 4.3-4. Spawning habitat utilization by anadromous salmon species and average run size in the middle Susitna
River. Large arrows indicate primary spawning habitat and thin arrows indicate secondary spawning habitat. Source:
Trihey and Entrix (1985) as modified from Sautner et al. (1984). Run size information from Barrett et al. (1985).
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Figure 4.3-5. Distribution of Chinook salmon spawning in the Middle River 1982 to 1985. Sources: Thompson et al.
(1986); Barrett et al. (1985, 1984, 1983). Age of Return.
Figure 4.3-6. Distribution of Chinook Salmon spawning in the Susitna River 1976 to 1984. Source: Jennings (1985).
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Figure 4.3-7. Escapement to Sunshine, Talkeetna, and Curry stations based upon mark-recapture techniques. No
escapement estimates were made for Talkeetna Station during 1985. Source: ADF&G (1983a), Barrett et al. (1984),
Barrett et al. (1985), Thompson et al. (1986).
Figure 4.3-8. Chinook salmon (age 0+) daily catch per unit effort and cumulative catch recorded at the mouth of Indian
River. Source: Roth et al. (1986).
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Figure 4.3-9. Chinook salmon (age 0+) daily catch per unit effort and cumulative catch recorded at the Talkeetna (upper
figure) and Flathorn (lower figure) stationary outmigrant traps, 1985. Source: Roth et al. (1986).
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Figure 4.3-10. Chinook salmon (age 1+) daily catch per unit effort and cumulative catc h recorded at the Talkeetna
(upper figure) and Flathorn (lower figure) stationary outmigrant traps, 1985. Source: Roth et al. (1986).
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Figure 4.3-11. Second run sockeye salmon escapement estimates to the Susitna River 1981 to 1985. No estimates for the
following stations and years Susitna/Flathorn (1982, 1983), Yentna (1982, 1985), and Talkeetna (1985). *: Estimate based
upon apportionment of sonar counts. Source: ADF&G (1981), ADF&G (1983 a), Barrett et al. (1984), Barrett et al.
(1985), Thompson et al. (1986).
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Figure 4.3-12. Distribution of sockeye salmon in the Susitna River Basin from ADF&G’s Anadromous Waters Catalog.
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Figure 4.3-13. Distribution of sockeye spawning in Middle Susitna River sloughs. Source: Jennings (1985), Thompson et
al. (1986).
Figure 4.3-14. Chum salmon escapement estimates to the Susitna River 1981 to 1985. No estimates for the following
stations and years Susitna/Flathorn (1982, 1983), Yentna (1982, 1985), and Talkeetna (1985). *: Estimate based upon
apportionment of sonar counts. Source: ADF&G (1981), ADF&G (1983a), Barrett et al. (1984), Barrett et al. (1985),
Thompson et al. (1986).
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Figure 4.3-15. Distribution of chum salmon in the Susitna River Basin from ADF&G’s Anadromous Waters Catalog.
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Figure 4.3-16. Spawning distribution of 210 chum salmon radio-tagged at Flathorn during 2009. Data Source: Merizon et
al. (2010).
Figure 4.3-17. Chum salmon spawning distribution among tributaries and sloughs in the Middle Susitna River based
upon peak counts. Data Source: Barrett et al. (1985), Thompson et al. (1986).
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Figure 4.3-18. Density distribution and juvenile chum salmon by macrohabitat type on the Susitna River between the
Chulitna River confluence and Devils Canyon, May through November 1983. Percentages are based on mean catch per
cell. Source: Dugan et al. (1984).
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Figure 4.3-19. Seasonal distribution and relative abundance of juvenile chum salmon on the Susitna River between the
Chulitna River confluence and Devils Canyon, May through November 1983. Source: Dugan et al. (1984).
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Figure 4.3-20. Coho salmon escapement estimates to the Susitna River 1981 to 1985. No estimates for the following
stations and years Susitna/Flathorn (1982, 1983), Yentna (1982, 1985), and Talkeetna (1985). *: Estimate based upon
apportionment of sonar counts. Source: ADF&G (1981), ADF&G (1983a), Barrett et al. (1984), Barrett et al. (1985),
Thompson et al. (1986).
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Figure 4.3-21. Distribution of coho salmon in the Susitna River Basin from ADF&G’s Anadromous Waters Catalog.
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Figure 4.3-22. Spawning distribution of 275 coho salmon radio-tagged at Flathorn during 2009. Source: Merizon et al.
(2010).
Figure 4.3-23. Density distribution and juvenile coho salmon by macrohabitat type on the Susitna River between the
Chulitna River confluence and Devils Canyon, May through November 1983. Percentages are based on mean catch per
cell. Source: Dugan et al. (1984).
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Figure 4.3-24. Seasonal distribution and relative abundance of juvenile coho salmo n on the Susitna River between the
Chulitna River confluence and Devils Canyon, May through November 1983. Source: Dugan et al. (1984).
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Figure 4.3-25. Pink salmon escapement estimates to the Susitna River 1981 to 1985. No estimates for the following
stations and years Susitna/Flathorn (1982, 1983), Yentna (1982, 1985), and Talkeetna (1985). *: Estimate based upon
apportionment of sonar counts. Source: ADF&G (1981), ADF&G (1983 a), Barrett et al. (1984), Barrett et al. (1985),
Thompson et al. (1986).
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Figure 4.3-26. Distribution of pink salmon in the Susitna River Basin from ADF&G’s Anadromous Waters Catalog.
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Figure 4.3-27. Pink salmon spawning distribution among tributaries in the Middle Susitna River based upon peak
counts.Source: Barrett et al. (1985), Thompson et al. (1986).
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Figure 4.3-28. Total catch of rainbow trout at DFH sites within the middle and lower Susitna River segments during 1982. Data from Schmidt et al. (1983).
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Figure 4.3-29. Total catch of Artic grayling at DFH sites in the Lower and Middle Susitna River during 1982. Data Source: Schmidt et al. (1983).
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Figure 4.3-30. Total catch of Dolly Varden at DFH sites during 1982 by gear type. Data Source: Schmidt et al. (1983).
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Figure 4.3-31. CPUE of burbot at DFH sites during 1982. Data Source: Schmidt et al. (1983)
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Figure 4.3-32. Total catch of round whitefish at DFH sites during 1982 by gear type. Data Source: Schmidt et al. (1983).
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Figure 4.3-33. Total catch of humpback whitefish at DFH sites during 1982 by gear type. Data Source: Schmidt et al. (1983).
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Figure 4.3-34. Total catch of longnose sucker at DFH sites during 1982 by gear type. Data Source: Schmidt et al. (1983).
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Figure 4.3-35. Total catch of threespine stickleback at DFH sites during 1982 by gear type. Data Source: Schmidt et al. (1983).
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Figure 4.3-36. Total catch of slimy sculpin at DFH sites during 1982 by gear type. Data Source: Schmidt et al. (1983).
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Figure 4.3-37. Deshka River Chinook salmon escapement. Source: Fair et al. (2010).
Figure 4.3-38. Escapement of Chinook salmon to Susitna River index streams other than the Deshka River. Source: Fair
et al. (2010).
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Figure 4.3-39. Mean catch rate of juvenile Chinook salmon at JAHS sites by turbidity bin in the Lower Susitna River,
1984. Source: Suchanek et al. (1985).
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Figure 4.3-40. Location of fish wheel capture sites, weirs, and radio-tracking stations in the Susitna River drainage, and
the terminal distribution of radio-tagged sockeye salmon based on aerial surveys, 2007 (top) and 2008 (bottom). Terminal
location does not necessarily mean a spawning location Source: Yanusz et al. (2011a, 2011b).
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Figure 4.3-41. Average chum fry catch rates at side channels in the lower river by turbidity bin during June through
mid-July 1984. Source: Suchanek et al. (1985)
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Figure 4.3-42. Seasonal distribution and relative abundance of juvenile coho salmon on the Lower Susitna River during
the open water period, 1984. Sources: Suchanek et al. (1985).
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Figure 4.3-43. Pink salmon escapement estimates to the Deshka River 1996 to 2012. Source:
http://www.adfg.alaska.gov/sf/FishCounts/.
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Figure 5.1-1. Relative abundance of juvenile Pacific salmon species in the Middle Segment of the Susitna River among
macro-habitat types during the open water season. Sources: Trihey and Associates and Entrix (1985) and Dugan et al.
(1984).
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Figure 6.1-1. Depth HSC developed during the 1980s for chum salmon spawning in the Middle Susitna River (Vincent-
Lang et al. 1984b), the Terror and Kizhuyak Rivers (Baldrige 1981), and Wilson River/Tunnel Creek (Lyons and Nadeau
1985).
Figure 6.1-2. Velocity HSC developed during the 1980s for chum salmon spawning in the Middle Susitna River (Vincent -
Lang et al. 1984b), the Terror and Kizhuyak Rivers (Baldrige 1981), and Wilson River/Tunnel Creek (Lyons and Nadeau
1985).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Chum Salmon Spawning
Susitna R. (middle)
Terror and Kizhuyak Rivers
Wilson River/Tunnel Creek
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Chum Salmon Spawning
Susitna R. (middle)
Terror and Kizhuyak Rivers
Wilson River/Tunnel Creek
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Figure 6.1-3. Substrate HSC developed during the 1980s for chum salmon spawning in the Middle Susitna River
(Vincent-Lang et al. 1984b).
Figure 6.1-4. Combined substrate/upwelling HSC developed during the 1980s for chum salmon spawning in the Middle
Susitna River (Vincent-Lang et al. 1984b). Codes ending in “.0” indicate upwelling absent and codes ending in “.1”
indicate upwelling present.
0.0
0.2
0.4
0.6
0.8
1.0
0 1 2 3 4 5 6 7 8 9Suitability
Substrate (code)
Chum Salmon Spawning
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
1.01.12.02.13.03.14.04.15.05.16.06.17.07.18.08.19.09.110.010.111.011.112.012.113.013.1SuitabilitySubstrate/Upwelling (code)
Chum Salmon Spawning
Susitna R. (middle)
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Figure 6.1-5. Depth HSC developed during the 1980s for juvenile chum salmon in the Lower (Suchanek et al. 1985) and
Middle (Suchanek et al. 1984a) Susitna River.
Figure 6.1-6. Velocity HSC developed during the 1980s for juvenile chum salmon in the Lower (Suchanek et al. 1985) and
Middle (Suchanek et al. 1984a) Susitna River. Note that the two curves are identical based on verification efforts in the
Lower River.
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Chum Salmon Juvenile
Susitna R. (lower)
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Chum Salmon Juvenile
Susitna R. (lower)
Susitna R. (middle)
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Figure 6.1-7. Depth HSC developed during the 1980s for sockeye salmon spawning in the Middle Susitna River (Vincent-
Lang et al. 1984b), and from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper
Talarik Creek (PLP 2011).
Figure 6.1-8. Velocity HSC developed during the 1980s for sockeye salmon spawning in the Middle Susitna River
(Vincent-Lang et al. 1984b), and from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and
Upper Talarik Creek (PLP 2011)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Sockeye Salmon Spawning
NFK/SFK/UT Combined
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Sockeye Salmon Spawning
NFK/SFK/UT Combined
Susitna R. (middle)
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Figure 6.1-9. Substrate HSC developed during the 1980s for sockeye salmon spawning in the Middle Susitna River
(Vincent-Lang et al. 1984b), and from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and
Upper Talarik Creek (PLP 2011).
Figure 6.1-10. Combined substrate/upswelling HSC developed during the 1980s for sockeye salmon spawning in the
Middle Susitna River (Vincent-Lang et al. 1984b). Codes ending in “.0” indicate upwelling absent and codes ending in
“.1” indicate upwelling present.
0.0
0.2
0.4
0.6
0.8
1.0
0 1 2 3 4 5 6 7 8 9Suitability
Substrate (code)
Sockeye Salmon Spawning
NFK/SFK/UT Combined
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
1.01.12.02.13.03.14.04.15.05.16.06.17.07.18.08.19.09.110.010.111.011.112.012.113.013.1SuitabilitySubstrate/Upwelling (code)
Sockeye Salmon Spawning
Susitna R. (middle)
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Figure 6.1-11. Depth HSC developed during the 1980s for juvenile sockeye salmon in the Lower (Suchanek et al. 1985)
and Middle (Suchanek et al. 1984a) Susitna River, and from combined observations in the North (NFK) and South (SFK)
Koktuli Rivers and Upper Talarik Creek (PLP 2011).
Figure 6.1-12. Velocity HSC developed during the 1980s for juvenile sockeye salmon in the Lower (Suchanek et al. 1985)
and Middle (Suchanek et al. 1984a) Susitna River, and from combined observations in the North (NFK) and South (SFK)
Koktuli Rivers and Upper Talarik Creek (PLP 2011).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Sockeye Salmon Juvenile
NFK/SFK/UT Combined
Susitna R. (lower)
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Sockeye Salmon Juvenile
NFK/SFK/UT Combined
Susitna R. (lower)
Susitna R. (middle)
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Figure 6.1-13. Depth HSC developed during the 1980s for Chinook salmon spawning in the Middle Susitna River
(Vincent-Lang et al. 1984a), from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper
Talarik Creek (PLP 2011), and for Wilson River/Tunnel Creek (Lyons and Nadeau 1985).
Figure 6.1-14. Velocity HSC developed during the 1980s for Chinook salmon spawning in the Middle Susitna River
(Vincent-Lang et al. 1984a), from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper
Talarik Creek (PLP 2011), and for Wilson River/Tunnel Creek (Lyons and Nadeau 1985).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Chinook Salmon Spawning
NFK/SFK/UT Combined
Susitna R. (middle)
Wilson River/Tunnel Creek
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Chinook Salmon Spawning
NFK/SFK/UT Combined
Susitna R. (middle)
Wilson River/Tunnel Creek
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Figure 6.1-15. Substrate HSC developed during the 1980s for Chinook salmon spawning in the Middle Susitna River
(Vincent-Lang et al. 1984a), and from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and
Upper Talarik Creek (PLP 2011).
Figure 6.1-16. Depth HSC developed during the 1980s for juvenile Chinook salmon in the Lower (Suchanek et al. 1985)
and Middle (Suchanek et al. 1984a) Susitna River, from combined observations in the North (NFK) and South (SFK)
Koktuli Rivers and Upper Talarik Creek (PLP 2011), for Wilson River/Tunnel Creek (Lyons and Nadeau 1985), and for
the Kenai River (Estes and Kuntz 1986).
0.0
0.2
0.4
0.6
0.8
1.0
0 1 2 3 4 5 6 7 8 9Suitability
Substrate (code)
Chinook Salmon Spawning
NFK/SFK/UT Combined
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Chinook Salmon Juvenile
NFK/SFK/UT Combined
Susitna R. (lower) Turbid
Susitna R. (lower) Clear
Susitna R. (middle)
Kenai River
Wilson River/Tunnel Creek
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Figure 6.1-17. Velocity HSC developed during the 1980s for juvenile Chinook salmon in the Lower (Suchanek et al. 1985)
and Middle (Suchanek et al. 1984a) Susitna River, from combined observations in the North (NFK) and South (SFK)
Koktuli Rivers and Upper Talarik Creek (PLP 2011), for Wilson River/Tunnel Creek (Lyons and Nadeau 1985), and for
the Kenai River (Estes and Kuntz 1986).
Figure 6.1-18. Depth HSC developed during the 1980s for coho salmon spawning in the Middle Susitna River (Vincent-
Lang et al. 1984a), from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik
Creek (PLP 2011), for the Terror and Kizhuyak Rivers (Baldrige 1981), and for Wilson River/Tunnel Creek (Lyons and
Nadeau 1985).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Chinook Salmon Juvenile
NFK/SFK/UT Combined
Susitna R. (lower)
Susitna R. (middle) Turbid
Susitna R. (middle) Clear
Kenai River
Wilson River/Tunnel Creek
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Coho Salmon Spawning
NFK/SFK/UT Combined
Susitna R. (middle)
Terror and Kizhuyak Rivers
Wilson River/Tunnel Creek
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Figure 6.1-19. Velocity HSC developed during the 1980s for coho salmon spaw ning in the Middle Susitna River (Vincent-
Lang et al. 1984a, from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik
Creek (PLP 2011), for the Terror and Kizhuyak Rivers (Baldrige 1981), and for Wilson River/Tunnel Cr eek (Lyons and
Nadeau 1985).
Figure 6.1-20. Substrate HSC developed during the 1980s for coho salmon spawning in the Middle Susitna River
(Vincent-Lang et al. 1984a), and from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and
Upper Talarik Creek (PLP 2011).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Coho Salmon Spawning
NFK/SFK/UT Combined
Susitna R. (middle)
Terror and Kizhuyak Rivers
Wilson River/Tunnel Creek
0.0
0.2
0.4
0.6
0.8
1.0
0 1 2 3 4 5 6 7 8 9Suitability
Substrate (code)
Coho Salmon Spawning
NFK/SFK/UT
Combined
Susitna R. (middle)
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Figure 6.1-21. Depth HSC developed during the 1980s for juvenile coho salmon in the Lower (Suchanek et al. 1985) and
Middle (Suchanek et al. 1984a) Susitna River, from combined observations in the North (NFK) and South (SFK) Koktuli
Rivers and Upper Talarik Creek (PLP 2011), for the Terror and Kizhuyak Rivers (Baldrige 1981), and for Wilson
River/Tunnel Creek (Lyons and Nadeau 1985). Note that the Middle and Lower Susitna River curves are identical based
on verification efforts in the Lower River.
Figure 6.1-22. Velocity HSC developed during the 1980s for juvenile coho salmon in the Lower (Suchanek et al. 1985)
and Middle (Suchanek et al. 1984a) Susitna River, from combined observations in the North (NFK) and South (SFK)
Koktuli Rivers and Upper Talarik Creek (PLP 2011), for the Terror and Kizhuyak Rivers (Baldrige 1981), and for
Wilson River/Tunnel Creek (Lyons and Nadeau 1985). Note that the Middle and Lower Susitna River curves are
identical based on verification efforts in the Lower River.
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Coho Salmon Juvenile
NFK/SFK/UT Combined
Susitna R. (lower)
Susitna R. (middle)
Terror and Kizhuyak Rivers
Wilson River/Tunnel Creek
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Coho Salmon Juvenile
NFK/SFK/UT Combined
Susitna R. (lower)
Susitna R. (middle)
Terror and Kizhuyak Rivers
Wilson River/Tunnel Creek
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Figure 6.1-23. Depth HSC developed during the 1980s for pink salmon spawning in the Middle Susitna River (Suchanek
et al. 1984a), the Terror and Kizhuyak Rivers (Baldrige 1981), and Wilson River/Tunnel Creek (Lyons and Nadeau 1985).
Figure 6.1-24. Velocity HSC developed during the 1980s for pink salmon spawning in the Middle Susitna River
(Suchanek et al. 1984a), the Terror and Kizhuyak Rivers (Baldrige 1981), and Wilson River/Tunnel Creek (Lyons and
Nadeau 1985).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Pink Salmon Spawning
Susitna R. (middle)
Terror and Kizhuyak Rivers
Wilson River/Tunnel Creek
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Pink Salmon Spawning
Susitna R. (middle)
Terror and Kizhuyak Rivers
Wilson River/Tunnel Creek
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Figure 6.1-25. Substrate HSC developed during the 1980s for pink salmon spawning in the Middle Susitna River
(Vincent-Lang et al. 1984a).
Figure 6.1-26. Depth HSC developed during the 1980s for rainbow trout adult in the Middle Susitna River (Suchanek et
al. 1984b).
0.0
0.2
0.4
0.6
0.8
1.0
0 1 2 3 4 5 6 7 8 9Suitability
Substrate (code)
Pink Salmon Spawning
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Rainbow Trout Adult
Susitna R. (middle)
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Figure 6.1-27. Velocity HSC developed during the 1980s for rainbow trout adult in the Middle Susitna River (Suchanek
et al. 1984b).
Figure 6.1-28. Depth HSC developed during the 1980s for adult arctic grayling in the Middle Susitna River (Suchanek et
al. 1984b), and from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik
Creek (PLP 2011).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Rainbow Trout Adult
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Arctic Grayling Adult
NFK/SFK/UT Combined
Susitna R. (middle)
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Figure 6.1-29. Velocity HSC developed during the 1980s for adult arctic grayling in the Middle Susitna Ri ver (Suchanek
et al. 1984b), and from combined observations in the North (NFK) and South (SFK) Koktuli Rivers and Upper Talarik
Creek (PLP 2011).
Figure 6.1-30. Depth HSC developed during the 1980s for adult round whitefish in the Middle Susitna River (Suchanek
et al. 1984b)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Arctic Grayling Adult
NFK/SFK/UT
Combined
Susitna R.
(middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Round Whitefish Adult
Susitna R. (middle)
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Figure 6.1-31. Velocity HSC developed during the 1980s for adult round whitefish in the Middle Susitna River (Suchanek
et al. 1984b)
Figure 6.1-32. Depth HSC developed during the 1980s for juvenile round whitefish in the Middle Susitna River
(Suchanek et al. 1984b).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Round Whitefish Adult
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Round Whitefish Juvenile
Susitna R. (middle)
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Figure 6.1-33. Velocity HSC developed during the 1980s for juvenile round whitefish in the Middle Susitna River
(Suchanek et al. 1984b).
Figure 6.1-34. Depth HSC developed during the 1980s for adult longnose sucker in the Middle Susitna River (Suchanek
et al. 1984b).
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Round Whitefish Juvenile
Susitna R. (middle)
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Depth (ft)
Longnose Sucker Adult
Susitna R. (middle)
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Figure 6.1-35. Velocity HSC developed during the 1980s for adult longnose sucker in the Middle Susitna River (Suchanek
et al. 1984b).
Figure 6.3-1. Daily discharge values from the USGS gage at Gold Creek (#15292000) on the Susitna River, from 17 July
to 19 September 2012.
0.0
0.2
0.4
0.6
0.8
1.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0Suitability
Velocity (ft/s)
Longnose Sucker Adult
Susitna R. (middle)
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Figure 6.3-2. Water temperature values from the mainstem Susitna River upstream of Whiskers Creek from July
through October 2012.
Figure 6.3-3. Example of a typical redd observed during spawning surveys. Depth, velocity, substrate, and redd
dimensions were measured at each redd.
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Figure 6.3-4. Example photos of methods used to evaluate visibility conditions using a secchi disk prior to conducting
microhabitat snorkel surveys.
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Figure 6.3-5. Utilizing snorkel surveys to identify fish habitat use of tributaries delta areas of the Susitna River, Alaska.
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Figure 6.3-6. Utilizing stick/pole seine surveys to identify fish habitat use in turbid water areas of Susitna River, Alaska.
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Figure 6.3-7. Adult arctic grayling captured during seining surveys of turbid water areas downstream of the proposed
Watana Dam site.
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Figure 6.3-8. Map depicting the Upper, Middle and Lower Segments of the Susitna River potentially influenced by the Susitna -Watana Hydroelectric Project and 2012
HSC sampling locations.
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Figure 6.3-9. Histogram plots of 2012 HSC observations for juvenile Chinook salmon normalized to the maximum
frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River,
Alaska.
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Figure 6.3-10. Histogram plots of 2012 HSC observations for juvenile Chinook salmon normalized to the maximum
frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River,
Alaska.
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Figure 6.3-11. Histogram plots of 2012 HSC observations for sockeye salmon spawning normalized to the maximum
frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River,
Alaska.
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Figure 6.3-12. Histogram plots of 2012 HSC observations for fry sockeye salmon normalized to the maximum frequency
equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River, Alaska.
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Figure 6.3-13. Histogram plots of 2012 HSC observations for pink salmon spawning normalized to the maximum
frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River,
Alaska.
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Figure 6.3-14. Histogram plots of 2012 HSC observations for chum salmon spawning normalized to the maximum
frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River,
Alaska.
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Figure 6.3-15. Histogram plots of 2012 HSC observations for fry chum salmon normalized to the maximum frequency
equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River, Alaska.
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Figure 6.3-16. Histogram plots of 2012 HSC observations for fry coho salmon normalized to the maximum frequency
equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River, Alaska.
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Figure 6.3-17. Histogram plots of 2012 HSC observations for juvenile coho salmon normalized to the maximum
frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River,
Alaska.
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Figure 6.3-18. Histogram plots of 2012 HSC observations for adult artic grayling normalized to the maximum frequency
equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River, Alaska.
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Figure 6.3-19. Histogram plots of 2012 HSC observations for juvenile arctic grayling normalized to the maximum
frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River,
Alaska.
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Figure 6.3-20. Histogram plots of 2012 HSC observations for fry arctic grayling normalized to the maximum frequency
equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River, Alaska.
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Figure 6.3-21. Histogram plots of 2012 HSC observations for adult rainbow trout normalized to the maximum frequency
equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River, Alaska.
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Figure 6.3-22. Histogram plots of 2012 HSC observations for juvenile humpback whitefish normalized to the maximum
frequency equal to 1.0 for depth (top), velocity (middle), and substrate (bottom) microhabitat components, Susitna River,
Alaska.
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Figure 7.1-1. Locations of instream flow habitat modeling sites established in the Middle Segment of the Susitna River during the 1980s Su-Hydro studies.
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Figure 7.1-2. Locations of instream flow habitat modeling sites established in the Lower Segment of the Susitna River during the 1980s Su-Hydro studies.
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Figure 7.1-3. Locations of instream flow transects and model types applied during the 1980s Su-Hydro studies in lower and upper Side Channel 11 and in Slough 11,
located near Gold Creek. Breaching flow s based on those studies are also depicted for various side channel and side slough habitats.
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Figure 7.1-4. Locations of instream flow transects and model types applied during the 1980s Su-Hydro studies in the Whiskers Slough complex. Breaching flows based
on those studies are also depicted for various side channel and side slough habitats.
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Figure 7.1-5. Illustration of the grid and cell sampling scheme employed at RJHAB modeling study sites. Sources:
Marshall et al. (1984).
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Figure 7.1-6. Conceptual figures illustrating procedure used for deriving non-modeled specific area (sa) Habitat
Availability Index curve using a modeled curve in a mainstem (ms) habitat, as applied during the 1980s Su-Hydro Studies
(see Aaserude et al. 1985; Steward et al. 1985). The procedure included lateral shifts (upper figure) due to adjustments
from differences in breaching flows (Qms, Qsa) as well as vertical shifts (middle figure) proportional to structural habitat
indices (SHIsa/SHIms) to account for differences in structural habitat quality. The lower figure shows final hypothetical
modeled and non-modeled specific area curves. Source: Aaserude et al. (1985).
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Figure 7.2-1. Exceedance flow values (USGS gage at Gold Creek), target sampling flows and anticipated model
extrapolation range for the Susitna River, Alaska.
May 01 Jun 01 Jul 01 Aug 01 Sep 01 Oct 01 Nov 01 Flow (cfs)0
10000
20000
30000
40000
50000
10% Exceedance
Median
90% Exceedance
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Figure 7.2-2. Conceptual layout of 2-D coarse and fine mesh modeling within the proposed Whiskers Slough Focus Area.
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Figure 7.2-3. Conceptual framework of the varial zone model.
Dry Zone
Maximum stage during previous 12 hours
Minimum stage during previous 7 days
Varial Zone
Continuously Wetted
Zone
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Figure 8.1-1. Mean daily intergravel and surface water temperature data from a spawning site in Slough 8A. Source:
Trihey (1982).
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Figure 8.1-2. Upwelling locations in the Middle Susitna River reported by Estes and Schmidt (1983).
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Figure 8.1-3. Upwelling locations at Slough 8A reported by Estes and Schmidt (1983).
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Figure 8.1-4. Upwelling locations at Slough 21 reported by Estes and Schmidt (1983).
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Figure 8.1-5. Turbidity and temperature measured at the Gold Creek Station and discharge measured at the Talkeetna
Station during 1984. Source: Harza-Ebasco (1985).
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Figure 8.1-6. Range of turbidity during breached and unbreached conditions at twelve side sloughs and side channels.
Source: Harza-Ebasco (1985).
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Figure 8.1-7. Hypothetical slough with delineated habitat zones. Source: Estes and Schmidt (1983).
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Figure 8.1-8. Typical arrangement of transects, grids, and cells at a JAHS site. Source: Dugan et al. (1984).
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Figure 8.1-9. Percent size composition of fine substrate (<0.08 in. diameter) of McNeil samples collected in various
habitat types in the middle Susitna River, Alaska. Source: Vining et al. (1985).
Figure 8.1-10. Percent size composition of fine substrate (<0.08 in. diameter) in McNeil samples collected at chum salmon
redds during May 1984 in study sites of middle Susitna River, Alaska. Source Vining et al. (1985).
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Figure 8.1-11. Relationship between percent survival of salmon embryos and the percent of fine substrate (<0.08 in.
diameter) within Whitlock-Vibert Boxes removed from artificial redds within selected habitats of the middle Susitna
River, Alaska. Source: Vining et al. (1985).
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APPENDIX 1. INDEX OF LOCATION NAMES AND RIVER MILE
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Sorted By River Mile
Sorted By Location Name
Location Name River Mile
Location Name River Mile
Alexander Creek 10.1
Alexander Creek 10.1
Flathorn Station 18.2
Anderson Creek 23.8
Anderson Creek 23.8
Answer Creek 84.0
Susitna Station 25.5
Birch Creek 88.4
Kroto Slough Mouth 30.1
Birch Creek Slough 88.4
Yentna River 30.1
Byers Creek (Chulitna R) 98.6
Mainstem Susitna Slough 31.0
Cache Creek 96.0
Mid Kroto Slough 36.3
Cache Creek Slough 95.5
Deshka River 40.6
Caswell Creek 63.0
Delta Islands 44.0
Chase Creek 106.4
Little Willow Creek 50.5
Cheechako Creek 152.4
Rustic Wilderness 58.1
Chinook Creek 157.0
Kashwitna River 61.0
Chulitna River 98.6
Caswell Creek 63.0
Curry Station 120.0
Slough West Bank 65.6
Dead Horse Creek 120.9
Sheep Creek Slough 66.1
Deadman Creek 186.7
Goose Creek 72.0
Delta Islands 44.0
Montana Creek 77.0
Deshka River 40.6
Sunshine Station 80.0
Devil Creek 161.0
Rabideaux Creek Slough 83.1
Devils Canyon Back Eddy 150.0
Parks Highway Bridge 83.9
Fat Canoe Island 147.0
Answer Creek 84.0
Fifth of July Creek 123.7
Question Creek 84.1
Fish Creek (Talkeetna R) 97.2
Sunshine Creek 85.7
Flathorn Station 18.2
Birch Creek Slough 88.4
Fog Creek 176.7
Birch Creek 88.4
Fourth of July Creek 131.1
Cache Creek Slough 95.5
Gash Creek 111.6
Cache Creek 96.0
Gold Creek 136.7
Fish Creek (Talkeetna R) 97.2
Gold Creek Bridge 136.7
Talkeetna River 97.2
Goose Creek 72.0
Byers Creek (Chulitna R) 98.6
Goose Creek 231.3
Troublesome Creek (Chulitna R) 98.6
Indian River 138.6
Swan Lake (Chulitna R) 98.6
Jack Long Creek 144.5
Chulitna River 98.6
Jay Creek 208.5
Slough 1 99.6
Kashwitna River 61.0
Slough 2 100.2
Kosina Creek 206.8
Whiskers Creek Slough 101.2
Kroto Slough Mouth 30.1
Whiskers Creek 101.4
Lane Creek 113.6
Slough 3B 101.4
Little Portage Creek 117.7
Slough 3A 101.9
Little Willow Creek 50.5
Talkeetna Station 103.0
Lower McKenzie Creek 116.2
Slough 4 105.2
Mainstem Susitna Slough 31.0
Chase Creek 106.4
Mid Kroto Slough 36.3
Slough 5 107.6
Montana Creek 77.0
Slough 6 108.2
Moose Slough 123.5
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Sorted By River Mile
Sorted By Location Name
Location Name River Mile
Location Name River Mile
Oxbow I 110.2
Oshetna River 233.4
Slash Creek 111.5
Oxbow I 110.2
Gash Creek 111.6
Parks Highway Bridge 83.9
Slough 6A 112.3
Portage Creek 148.9
Slough 7 113.2
Question Creek 84.1
Lane Creek 113.6
Rabideaux Creek Slough 83.1
Slough 8 113.7
Rustic Wilderness 58.1
Lower McKenzie Creek 116.2
Sheep Creek Slough 66.1
Upper McKenzie Creek 116.7
Sherman Creek 130.8
Little Portage Creek 117.7
Side Channel 10A 132.1
Curry Station 120.0
Skull Creek 124.7
Dead Horse Creek 120.9
Slash Creek 111.5
Susitna Side Channel 121.6
Slough 1 99.6
Slough 8D 121.8
Slough 10 133.8
Slough 8C 121.9
Slough 10 133.8
Slough 8B 122.2
Slough 10 Side Channel 133.7
Moose Slough 123.5
Slough 11 135.3
Fifth of July Creek 123.7
Slough 12 135.4
Slough A prime 124.6
Slough 13 135.9
Slough A 124.7
Slough 14 135.9
Skull Creek 124.7
Slough 15 137.2
Slough 8A 125.1
Slough 16B 137.3
Slough B 126.3
Slough 17 138.9
Slough 9 128.3
Slough 18 139.1
Slough 9B 129.2
Slough 19 139.7
Sherman Creek 130.8
Slough 2 100.2
Fourth of July Creek 131.1
Slough 20 140.0
Side Channel 10A 132.1
Slough 21 141.1
Slough 10 Side Channel 133.7
Slough 21 Side Channel 140.5
Slough 10 133.8
Slough 21A 144.3
Slough 9A 133.8
Slough 22 144.3
Slough 10 133.8
Slough 3A 101.9
Slough 11 135.3
Slough 3B 101.4
Slough 12 135.4
Slough 4 105.2
Slough 13 135.9
Slough 5 107.6
Slough 14 135.9
Slough 6 108.2
Gold Creek 136.7
Slough 6A 112.3
Gold Creek Bridge 136.7
Slough 7 113.2
Slough 15 137.2
Slough 8 113.7
Slough 16B 137.3
Slough 8A 125.1
Indian River 138.6
Slough 8B 122.2
Slough 17 138.9
Slough 8C 121.9
Slough 18 139.1
Slough 8D 121.8
Slough 19 139.7
Slough 9 128.3
Slough 20 140.0
Slough 9A 133.8
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Sorted By River Mile
Sorted By Location Name
Location Name River Mile
Location Name River Mile
Slough 21 Side Channel 140.5
Slough 9B 129.2
Slough 21 141.1
Slough A 124.7
Slough 21A 144.3
Slough A prime 124.6
Slough 22 144.3
Slough B 126.3
Jack Long Creek 144.5
Slough West Bank 65.6
Fat Canoe Island 147.0
Sunshine Creek 85.7
Portage Creek 148.9
Sunshine Station 80.0
Devils Canyon Back Eddy 150.0
Susitna Side Channel 121.6
Cheechako Creek 152.4
Susitna Station 25.5
Chinook Creek 157.0
Swan Lake (Chulitna R) 98.6
Devil Creek 161.0
Talkeetna River 97.2
Fog Creek 176.7
Talkeetna Station 103.0
Tsusena Creek 181.3
Troublesome Creek (Chulitna R) 98.6
Deadman Creek 186.7
Tsusena Creek 181.3
Watana Creek 194.1
Upper McKenzie Creek 116.7
Kosina Creek 206.8
Watana Creek 194.1
Jay Creek 208.5
Whiskers Creek 101.4
Goose Creek 231.3
Whiskers Creek Slough 101.2
Oshetna River 233.4
Yentna River 30.1
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 1 - Page 4 March 2013
APPENDIX 2. LISTING OF FISH AND AQUATIC STUDIES DOCUMENTS
AND REPORTS RESULTING FROM THE 1980S SU-HYDRO PROJECT
(EACH OF THESE DOCUMENTS SHOULD BE COMPILED AND MADE
AVAILABLE AS PDFS FOR SEPARATE DISK THAT CAN BE ATTACHED
TO THE COMPENDIUM)
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 2 - Page 1 March 2013
Citation Year Title
APA
Document
Number
No. of
APA
Docs
Aaserude et al. 1985 1985 Characterization of aquatic habitats in the Talkeetna-to-Devil
Canyon segment of the Susitna River, Alaska
2919 1
ADF&G 1981 1981 Adult Anadromous Fisheries Project 324 1
ADF&G 1982a 1982 Aquatic Studies Procedures Manual and Appendices 3554, 3555 2
ADF&G 1982b 1982 Stock Separation Feasibility 320 1
ADF&G 1983a 1983 Adult Anadromous Fish Studies, 1982 and Appendices 588, 589 2
ADF&G 1983b 1983 Aquatic Studies Procedures Manual 938 1
ADF&G 1983c 1983 Summarization of Volumes 2, 3, 4; Parts I and II, and 5 96 1
ADF&G 1984 1984 ADF&G Su Hydro Aquatic Studies (May 1983 - June 1984)
Procedures Manual and Appendices
885, 886 2
ADF&G 1985 1985 Resident and Juvenile Anadromous Studies Procedures
Manual
3014 1
Ashton and Klinger-
Kingsley 1985
1985 Response of Aquatic Habitat Surface Areas to Discharge in
the Yentna to Talkeetna Reach of the Susitna River.
2774 1
Ashton and Trihey 1985 1985 Assessment of Access by Spawning Salmon into Tributaries
of the Lower Susitna River
2775 1
Barrett 1974 1974 An Assessment of the Anadromous Fish Populations in the
Upper Susitna River Watershed between Devil Canyon and
Chulitna River
1612 1
Barrett 1975 1975 December, January, and February Investigations on the
Upper Susitna River Watershed Between Devil Canyon And
Chulitna River
1609 1
Barrett et al. 1984 1984 Adult Anadromous Fish Investigations (May -October 1983) 1450 1
Barrett et al. 1985 1985 Adult Anadromous Fish Investigations (May - October 1984) 2748 1
Barrick et al. 1983 1983 Upper Susitna River Salmon Enhancement Study, Draft
report
522 1
Bigler and Levesque
1985
1985 Lower Susitna River Preliminary Chum Salmon Spawning
Habitat Assessment
3504 1
Blakely et al. 1985 1985 Salmon Passage Validation Studies 2854 1
Burgess 1983 1983 Slough Hydrogeology Report 519 1
Cannon 1986 1986 Susitna River Aquatic Studies Review: Findings And
Recommendations
3501 1
Delaney et al. 1981a 1981 Resident Fish Investigation on the Lower Susitna River 318 1
Delaney et al. 1981b 1981 Juvenile Anadromous Fish Study on the Lower Susitna River 1310 1
Delaney et al. 1981c 1981 Resident Fish Investigation on the Upper Susitna River 316 1
Dugan et al. 1984 1984 The distribution and relative abundance of juvenile salmon in
the Susitna River drainage
1784 1
Entrix 1985a 1985 Access Corridor, Construction Zone And Transmission
Corridor Fish Impact Assessment and Mitigation Plan
2921 1
Entrix 1985b 1985 Impoundment Area Fish Impact Assessment and Mitigation
Plan
2922 1
Estes and Bingham
1983
1982 Aquatic Studies Program 1982 517 1
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 2 - Page 2 March 2013
Citation Year Title
APA
Document
Number
No. of
APA
Docs
Estes and Schmidt
1983
1983 Aquatic Habitat and Instream Flow Studies 1982 (Parts I and
II). Part II and Appendices A, B-D, E-J available on ARLIS.
585, 586,
587
3
Estes et al. 1981 1981 Aquatic Habitat and Instream Flow Project; Volume 1 and
Volume2, Parts 1 and 2.
311, 312,
1307
3
Friese 1975 1975 Preauthorization Assessment of Anadromous Fish
Population Upper Susitna River Watershed in the Vicinity of
Proposed Devil Canyon Hydroelectric Project
549 1
Hansen and Richards
1985
1985 Availability of Invertebrate Food Sources for Rearing
Juvenile Chinook Salmon In Turbid Susitna River Habitats
2846 1
Harza-Ebasco 1985 1985 Susitna Hydroelectric Project License Application Exhibit E
Chapters 1 and 2 (Tables, Figures); Chapter 3 (References);
Chapter 10
3430,
3431,
3432,
3433,
3435, 3438
6
Harza-Ebasco and
R&M 1984
1984 Slough Geohydrology Studies 1718 1
Hilliard et al. 1985 1985 Hydraulic relationships and model calibration procedures at
1984 study sites in the Talkeetna-to-Devil Canyon segment
of the Susitna River, Alaska and Appendices A-C
2898, 2899 2
Hoffman 1985 1985 Summary Of Salmon Fishery Data For Selected Middle
Susitna River Sites
2749 1
Hoffman et al. 1983 1983 Winter Aquatic Studies (October 1982 - May 1983) 397 1
Jennings 1985 1985 Fish Resources and Habitats in the Middle Susitna River 2744 1
Klinger and Trihey 1984 1984 Response of Aquatic Habitat Surface Areas to Mainstem
Discharge in the Talkeetna to Devil Canyon Reach of the
Susitna River, Alaska.
1693 1
Klinger-Kingsley et al.
1985
1985 Response of aquatic habitat surface areas to mainstem
discharge in the Talkeetna-to-Devil Canyon segment of the
Susitna River, Alaska and Appendix 1 (Maps)
2945,
2945_maps
2
Marshall et al. 1984 1984 Juvenile salmon rearing habitat models 1784 1
Meyer et al. 1984 1984 Assessment of the Effects of the Proposed SHP on Instream
Temperature and Fishery Resources in the Watana to
Talkeetna Reach
2330 1
Quane et al. 1984 1984 Stage and discharge investigations 1930 1
Quane et al. 1985 1985 Hydrological Investigations at Selected Lower Susitna River
Study Sites
2736 1
R&M 1981 1981 Attachment D to Hydrographic Surveys: Susitna River Mile
Index
483 1
Riis 1977 1977 Pre-authorization Assessment of the Proposed Susitna River
Hydroelectric Projects: Preliminary Investigations of Water
Quality and Aquatic Species Composition
1610 1
Riis and Friese 1978 1978 Preliminary Environmental Assessment of Hydroelectric
Development on the Susitna River
1613 1
Roth and Stratton 1985 1985 The migration and growth of juvenile salmon in Susitna
River, 1985
2836 1
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 2 - Page 3 March 2013
Citation Year Title
APA
Document
Number
No. of
APA
Docs
Roth et al. 1984 1984 The outmigration of juvenile salmon from the Susitna River
above the Chulitna River confluence
1784 1
Roth et al. 1986 1986 The Migration and Growth of the Juvenile Salmon in the
Susitna River, 1985
3413 1
Sandone et al. 1984 1984 Evaluations of chum salmon spawning habitat in selected
tributary mouth habitats of the middle Susitna River
1937 1
Sautner and Stratton
1983
1983 Upper Susitna River Impoundment Studies 1982 590 1
Sautner and Stratton
1984
1984 Access and transmission corridor studies 2049 1
Sautner et al. 1984 1984 An evaluation of passage conditions for adult salmon in
sloughs and side channels of the middle Susitna River
1935 1
Schmidt and Bingham
1983
1983 Report Synopsis of the 1982 Aquatic Studies and Analysis of
Fish and Habitat Relationships and Appendices
40a_ver2,
40
2
Schmidt and Stratton
1984
1984 Population dynamics of Arctic grayling in the Upper Susitna
Basin
2049 1
Schmidt et al. 1983 1983 Resident and Juvenile Anadromous Fish Studies on Susitna,
Below Devil Canyon and Appendices
486, 487 2
Seagren and Wilkey
1985a
1985 Preliminary Evaluations of Potential Fish Mitigation Sites in
the Middle Susitna River
2908 1
Seagren and Wilkey
1985b
1985 Summary of Water Temperature and Substrate Data from
Selected Salmon Spawning and Groundwater Upwelling
Sites in the Middle Susitna River
2913 1
Steward et al. 1985 1985 Response of juvenile Chinook habitat to mainstem discharge
in the Talkeetna to Devil Canyon Segment of the Susitna
River, Alaska
2909 1
Stratton 1986 1986 Summary of juvenile Chinook and coho salmon winter
studies in the Middle Susitna River, 1984-1985
3063 1
Suchanek et al. 1984a 1984 Resident fish habitat studies 1784 1
Suchanek et al. 1984b 1984 Juvenile salmon rearing suitability criteria 1784 1
Suchanek et al. 1985 1985 The relative abundance, distribution, and instream flow
relationships of juvenile salmon in the Lower Susitna River
2836 1
Sundet 1986 1986 Winter resident fish distribution and habitat studies
conducted in the Susitna River below Devil Canyon, 1984-
1985
3062 1
Sundet and Pechek
1985
1985 Resident fish distribution and life history in the Susitna River
below Devil Canyon
2837 1
Sundet and Wenger
1984
1984 Resident fish distribution and population dynamics in the
Susitna River below Devil Canyon
1784 1
Thompson et al. 1986 1986 Adult Salmon Investigations (May-October 1985) and
Appendix
3412,
3412_v2
2
Trihey & Associates
and Entrix 1985
1985 Instream flow relationships report, Volume 1 3060 1
Trihey & Associates
and Entrix 1985
1985 Instream flow relationships report, Volume 2 3061 1
Trihey 1982a 1982 1982 Winter Temperature Study Open File Report 526 1
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 2 - Page 4 March 2013
Citation Year Title
APA
Document
Number
No. of
APA
Docs
Trihey 1982b 1982 Preliminary Assessment of Access by Spawning Salmon to
Side Slough Habitat above Talkeetna
510 1
Trihey 1983 1983 Preliminary Assessment of Access by Spawning Salmon into
Portage Creek and Indian River
508 1
Trihey and Hilliard 1986 1986 Response of Chum Salmon Spawning Habitat to Discharge
in the Talkeetna to Devil Canyon Segment of the Susitna
River, Alaska
3423 1
Vincent-Lang and
Queral 1984
1984 Eulachon spawning habitat in the Lower Susitna River 1934 1
Vincent-Lang et al.
1984a;
1984 Habitat suitability criteria for Chinook, coho, and pink salmon
spawning in tributaries of the middle Susitna River
1938 1
Vincent-Lang et al.
1984b
1984 An evaluation of chum and sockeye salmon spawning
habitat in sloughs and side channels of the Middle Susitna
River
1936 1
Vining et al. 1985 1985 An evaluation of the incubation life-phase of chum salmon in
the middle Susitna River, Alaska, and Appendices A-E;
Appendix F
2658, 2659 2
Wangaard and Burger
1983
1983 Effects of Various Water Temperature Regimes on the Egg
and Alevin Incubation of Susitna River Chum and Sockeye
Salmon
317 1
Wilson 1985 1985 Task 31 Primary Production Monitoring Report 4018 1
Wilson et al. 1984 1984 Effects of Project-related Changes in Temperature, Turbidity
and Stream Discharge on Upper Susitna Salmon Resources
During June - Sept
454 1
Woodward-Clyde
Consultants 1984
1984 Interim Mitigation Plan for Chum Spawning Habitat in Side
Sloughs of the Middle Susitna River
2332 1
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 March 2013
APPENDIX 3. SUMMARY OF 1980S INSTREAM FLOW HABITAT
MODELING SITES
REPORT 2012 INSTREAM FLOW PLANNING STUDY
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 3 - Page 1 March 2013
Appendix 3 is provided in a separate file.
1. Susitna Flow