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Susitna-Watana Hydroelectric Project Document
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Title:
Fish and aquatics instream flow study, Study plan Section 8.5 : Initial study
report
SuWa 207
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Prepared by R2 Resource Consultants, Inc.
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Draft initial study report
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Susitna-Watana Hydroelectric Project document number 207
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[Anchorage : Alaska Energy Authority, 2014]
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February 2014
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Study plan Section 8.5
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Appendices D-F ; Appendices G-I.
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Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Fish and Aquatics Instream Flow Study
Study Plan Section 8.5
Initial Study Report
Prepared for
Alaska Energy Authority
Prepared by
R2 Resource Consultants, Inc.
February 2014 Draft
INITIAL STUDY REPORT FISH AND AQUATICS INSTREAM FLOW STUDY (8.5)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i February 2014 Draft
TABLE OF CONTENTS
Executive Summary ................................................................................................................... xviii
1. Introduction ......................................................................................................................... 1
2. Study Objectives ................................................................................................................. 2
3. Study Area .......................................................................................................................... 4
4. Methods............................................................................................................................... 4
4.1. IFS Analytical Framework ...................................................................................... 5
4.1.1. Methodology ................................................................................... 5
4.1.2. Variances ......................................................................................... 7
4.2. River Stratification and Study Area Selection ........................................................ 7
4.2.1. Methodology ................................................................................... 7
4.2.2. Variances from Study Plan ........................................................... 17
4.3. Hydrologic Data Analysis ..................................................................................... 18
4.3.1. Methodology ................................................................................. 18
4.3.2. Variances from Study Plan ........................................................... 21
4.4. Reservoir Operations Model and Open-water Flow Routing Model .................... 22
4.4.1. Methodology ................................................................................. 23
4.4.2. Variances from Study Plan ........................................................... 26
4.5. Habitat Suitability Criteria Development ............................................................. 26
4.5.1. Methodology ................................................................................. 27
4.5.2. Variances from Study Plan ........................................................... 40
4.6. Habitat-Specific Model Development .................................................................. 42
4.6.1. Methodology ................................................................................. 43
4.6.2. Variances from Study Plan ........................................................... 50
4.7. Temporal and Spatial Habitat Analyses ................................................................ 50
4.7.1. Methodology ................................................................................. 51
4.7.2. Variances from Study Plan ........................................................... 51
4.8. Instream Flow Study Integration .......................................................................... 51
4.8.1. Methodology ................................................................................. 52
4.8.2. Variances from Study Plan ........................................................... 52
5. Results ............................................................................................................................... 52
5.1. IFS Analytical Framework .................................................................................... 53
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5.2. River Stratification and Study Area Selection ...................................................... 53
5.2.1. Stratification .................................................................................. 53
5.2.2. Study Area Selection ..................................................................... 53
5.2.3. Middle River Study Area/Site Selection ....................................... 54
5.2.4. Lower River Study Area/Study Site Selection .............................. 57
5.3. Hydrologic Data Analysis ..................................................................................... 57
5.3.1. Mainstem Susitna River ................................................................ 57
5.3.2. Tributaries to Susitna River .......................................................... 58
5.3.3. Realtime Hydrologic Data and Network ....................................... 59
5.3.4. Representative Years .................................................................... 59
5.3.5. Indicators of Hydrologic Alteration and Environmental Flow
Components .................................................................................. 60
5.4. Reservoir Operations and Open-water Flow Routing Modeling .......................... 60
5.4.1. Reservoir Operations Model ......................................................... 60
5.4.2. Open-water Flow Routing Model ................................................. 61
5.5. Habitat Suitability Criteria Development ............................................................. 64
5.5.1. Selection of Target Species and Life Stages ................................. 65
5.5.2. Development of Draft HSC Curves Using Existing Information . 65
5.5.3. HSC/HSI Study Area Selection .................................................... 67
5.5.4. Collect Site-Specific Habitat Suitability Information ................... 67
5.5.5. Habitat Availability Data Collection ............................................ 72
5.5.6. Habitat Utilization Frequency Histograms/HSC/HSI Curve
Development ................................................................................. 73
5.5.7. Methods for HSC/HSI Curve Development ................................. 74
5.5.8. Winter Habitat Use Sampling ....................................................... 75
5.5.9. River Productivity ......................................................................... 78
5.5.10. Draft Periodicity Tables ................................................................ 78
5.5.11. Biological Cues Study................................................................... 78
5.5.12. Relationship between Microhabitat Use and Fish Abundance ..... 79
5.5.13. Stranding and Trapping ................................................................. 80
5.6. Habitat-Specific Model Development .................................................................. 80
5.6.1. Habitat Model Selection ............................................................... 80
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5.6.2. Field Coordination and Collection of Physical and Hydraulic Data
....................................................................................................... 80
5.6.3. Model Development ...................................................................... 82
5.6.4. Habitat Evaluation Metrics ........................................................... 83
5.7. Temporal and Spatial Analysis ............................................................................. 86
5.8. Instream Flow Study Integration .......................................................................... 87
6. Discussion ......................................................................................................................... 87
6.1. IFS Analytical Framework .................................................................................... 87
6.2. River Stratification and Study Area Selection ...................................................... 87
6.3. Hydrologic Data Analysis ..................................................................................... 87
6.3.1. Mainstem Susitna River ................................................................ 87
6.3.2. Tributaries to the Susitna River .................................................... 88
6.3.3. Realtime Hydrologic Data and Network ....................................... 89
6.3.4. Representative Years .................................................................... 89
6.3.5. Indicators of Hydrologic Alteration and Environmental Flow
Components .................................................................................. 89
6.4. Reservoir Operations and Open-water Flow Routing Modeling .......................... 90
6.4.1. Reservoir Operations Model ......................................................... 90
6.4.2. Open-water Flow Routing Model ................................................. 90
6.5. Habitat Suitability Criteria Development ............................................................. 91
6.5.1. Selection of Priority Species and Life Stage ................................. 91
6.5.2. HSC/HSI Study Site Selection ...................................................... 91
6.5.3. Collection of Site-Specific Microhabitat Utilization and
Availability Data ........................................................................... 92
6.5.4. Habitat Utilization Frequency Histograms ................................... 92
6.5.5. Winter Studies ............................................................................... 92
6.5.6. Stranding and Trapping ................................................................. 92
6.5.7. River Productivity ......................................................................... 92
6.5.8. Interim Periodicity Tables............................................................. 93
6.5.9. Biological Cues ............................................................................. 93
6.5.10. Relationship Between Microhabitat Use and Fish Abundance ..... 93
6.6. Habitat-Specific Model Development .................................................................. 94
6.6.1. Habitat Model Selection ............................................................... 94
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6.6.2. Field Coordination and Collection of Physical and Hydraulic Data
....................................................................................................... 94
6.6.3. Model Development ...................................................................... 95
6.6.4. Fish Habitat Evaluation Metrics ................................................... 96
6.7. Temporal and Spatial Habitat Analyses ................................................................ 97
6.8. Instream Flow Study Integration .......................................................................... 97
7. Completing the Study ....................................................................................................... 97
8. Literature Cited ................................................................................................................. 97
9. Tables .............................................................................................................................. 108
10. Figures............................................................................................................................. 150
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LIST OF TABLES
Table 4.2-1. Geomorphic reach designations for the Upper River (UR) Segment, Middle River
(MR) Segment, and Lower River (LR) Segment of the Susitna River. .......................... 109
Table 4.2-2. Nested and tiered habitat mapping units, categories, and definitions. .................. 110
Table 4.2-3. Locations, descriptions and selection rationale of 10 Final Focus Areas identified
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. ....................................................... 112
Table 4.2-4. Summary of Potential Effects of With-Project Flows on Tributaries of the Lower
Susitna River from 1980s studies, and tributary mouths proposed for modeling in 2013
(indicated by highlighting) (1980s summary adapted from Ashton and Trihey (1985)).113
Table 4.3-1. Susitna Real-Time Reporting Network Stations. .................................................. 114
Table 4.3-2. Summary of gaging stations established on Susitna River in 2012....................... 115
Table 4.3-3. Tributary gaging site information. ......................................................................... 115
Table 4.3-4. Period of record of flows measured by the USGS on the Susitna River. .............. 116
Table 4.3-5. Period of record of flows measured by the USGS on tributaries of the Susitna
River. ............................................................................................................................... 116
Table 4.4-1. Comparison of the content contained in the three versions of the hydraulic routing
model............................................................................................................................... 117
Table 4.4-2. Summary of 2012-2013 surface water data collected at selected ESS stations in the
Susitna River. ESS = AEASusitnaSurface water measurements. .................................. 118
Table 4.5-1. Common names, scientific names, life history strategies, and habitat use of fish
species within the Lower, Middle, and Upper Susitna River, based on sampling during
the 1980s (from HDR 2011). .......................................................................................... 119
Table 4.5-2. Priority ranking of fish species for development of site-specific Habitat Suitability
Curves for the Susitna River, Alaska. ............................................................................. 120
Table 4.5-3. Summary of HSC curves developed during 1980s Susitna Studies. ..................... 120
Table 4.5-4. Summary of habitat units selected from within each Focus Area for HSC sampling
in 2013. ........................................................................................................................... 121
Table 4.5-5. Substrate classification system used in development of HSC/HSI curves for the
Susitna-Watana Project (adapted from Wentworth 1922). ............................................. 121
Table 4.5-6. Summary of velocity meter and water quality probe specifications. .................... 121
Table 4.6-1. Assessment of physical and biological processes and potential habitat modeling
techniques. ...................................................................................................................... 122
Table 5.2-1. Metrics used to compare the representation and proportionality of habitat types
between Focus Areas and non-Focus Areas within each geomorphic reach. ................. 123
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Table 5.2-2. Estimated bias for each proportionality metric (total for reach – Focus Area) where
estimates could be made. Statistical comparison was made using a t-test or
nonparametric alternative when the sample size (number of geomorphic reaches with bias
estimate) was greater than three. ..................................................................................... 124
Table 5.2-3. Identification of existing Focus Area boundaries and counterpart locations of areas
selected via a random systematic approach. ................................................................... 124
Table 5.2-4. Estimated bias for each proportionality metric (total for reach – Focus Area) where
estimates could be made for random Focus Areas. Statistical comparison was made using
a t-test or nonparametric alternative when the sample size (number of geomorphic
reaches with bias estimate) was greater than three. ........................................................ 125
Table 5.3-1. 2012 and provisional 2013 cross-sectional data ( indicate measured WSEs). ... 126
Table 5.3-2. Summary of Focus Area measurements. ............................................................... 131
Table 5.3-3. Tributary gaging streamflow and staff gage measurements collected in 2013. .... 138
Table 5.4-1. USGS Gage No. 15292000 – Susitna River at Gold Creek (cfs). ......................... 139
Table 5.4-2. Inflows to Watana Reservoir (cfs). ........................................................................ 140
Table 5.5-1. Number of microhabitat use measurements by Focus Area and habitat type for all
species and life stages observed during the 2013 HSC surveys of the Middle River
Segment of the Susitna River, Alaska. ............................................................................ 141
Table 5.5-2. Number of individual sampling events by Focus Area, habitat type, and sampling
session during 2013 HSC sampling in the Middle Susitna River, Alaska. ..................... 142
Table 5.5-3. Number of HSC microhabitat use observations by sampling session for each
species and life stage collected during the summer 2013 sampling of the Middle Segment
of the Susitna River, Alaska............................................................................................ 143
Table 5.5-4. Number of microhabitat availability measurements by Focus Area and habitat type
collected during the 2013 field season for the Middle Segment of the Susitna River,
Alaska. ............................................................................................................................ 144
Table 5.5-5. Summary statistics for water quality variables collected during summer 2013 in
habitat units within the Middle Segment of the Susitna River, Alaska. ......................... 145
Table 5.5-6. Number of water quality observations by metric bin and habitat type collected
during summer 2013 HSC surveys in the Middle Segment of the Susitna River, Alaska.
......................................................................................................................................... 146
Table 5.5-7. Total number of fish captured by species and life stage during daytime and
nighttime electrofishing surveys conducted in FA-104 (Whiskers Slough) and FA-128
(Slough 8A) in March and April 2013. ........................................................................... 147
Table 5.5-8. Total number of HSC observations recorded during electrofish sampling in March
and April 2013 by species and life stage. ....................................................................... 147
Table 5.5-9. Number of Hess, algae, and snag samples collected with associated depth (D),
velocity (V), and substrate composition (Sub) measurements for 2013 sampling during
three index events (Spr= Spring, Sum=Summer, Fall) in the Middle and Lower River
Segments of the Susitna River for the River Productivity Study. ................................... 148
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Table 5.5-10. Source and projected availability of water quality and fish abundance data needed
for completion of an evaluation of relationships between fish abundance and water
quality within Middle River Segment Focus Areas. ....................................................... 149
LIST OF FIGURES
Figure 2-1. Study interdependencies for Fish and Aquatics Instream Flow Study. .................. 151
Figure 3-1. Map depicting the Upper, Middle and Lower Segments of the Susitna River
potentially influenced by the Susitna-Watana Hydroelectric Project. ............................ 152
Figure 3-2. Map of the Middle Segment of the Susitna River depicting the eight Geomorphic
Reaches and locations of ten Focus Areas. No Focus Areas were located in MR-3 and
MR-4 due to safety issues related to sampling within or proximal to Devils Canyon. .. 153
Figure 3-3. Map of the Lower Segment of the Susitna River depicting the six Geomorphic
Reaches. Focus Areas have not been identified in this segment but will be considered
pending results of open-water flow routing modeling. ................................................... 154
Figure 4.1-1. Conceptual framework for the Susitna-Watana Instream Flow Study depicting
integration of habitat specific models and riverine processes to support integrated
resource analyses; and integration of riverine processes to develop fish and aquatic
habitat specific models. ................................................................................................... 156
Figure 4.2-1. Map showing FA-184 (Watana Dam) that begins at Project River Mile 184.7 and
extends upstream to PRM 185.7. This Focus Area is located about 1.4 miles downstream
of the proposed Watana Dam site near Tsusena Creek. .................................................. 157
Figure 4.2-2. Map showing FA-173 (Stephan Lake)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. ..................................................................... 158
Figure 4.2-3. Map showing FA-151 (Portage Creek)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. ........................................................................................................... 159
Figure 4.2-4. Map showing FA-144 (Slough 21) 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. ........................................... 160
Figure 4.2-5. Map showing FA-141 (Indian River) 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 including Slough 17. ................. 161
Figure 4.2-6. Map showing FA-138 (Gold Creek) beginning at Project River Mile 138.5 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. ............................................................................................. 162
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Figure 4.2-7. Map showing FA-128 (Slough 8A) 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. ................................... 163
Figure 4.2-8. Map showing FA-115 (Slough 6A) 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. ................................................................................................................................... 164
Figure 4.2-9. Map showing FA-113 (Oxbow 1) beginning at Project River Mile 113.6 and
extends upstream to PRM 115.3. This Focus Area consists of side channel and slough
habitats including Oxbow 1. ........................................................................................... 165
Figure 4.2-10. Map showing FA-104 (Whiskers Slough) 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. ................................................................................... 166
Figure 4.2-11. Map showing location of lower Susitna River instream flow-fish habitat transects
in Geomorphic Reach LR-1 in the vicinity of Trapper Creek. ....................................... 167
Figure 4.2-12. Map showing location of lower Susitna River instream flow-fish habitat transects
in Geomorphic Reach LR-2 in the vicinity of Caswell Creek. These transects will be
measured in 2014. 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. ......................................................... 168
Figure 4.3-1. 2013 Tributary Gaging Locations. ....................................................................... 169
Figure 4.4-1. Mainstem gaging locations. ................................................................................. 170
Figure 4.5-1. Map showing 2013 HSC sampling locations (yellow circles) in relationship to
geomorphic reaches and Focus Areas (red circles) in the Middle River Segment of the
Susitna River, Alaska. ..................................................................................................... 171
Figure 4.5-2. Locations of 2012-2013 winter sites for continuous and instantaneous water
quality monitoring, water level monitoring, and fish sampling in FA-104 (Whiskers
Slough). ........................................................................................................................... 172
Figure 4.5-3. Locations of 2012-2013 winter sites for continuous and instantaneous water
quality monitoring, water level monitoring, and fish sampling in FA-128 (Slough 8A).
......................................................................................................................................... 173
Figure 5.2-1. Percent of main channel in single main, split main, and braided main channel
habitat by geomorphic reach and Focus Area (F), non-Focus Area (NF), and total (T). 174
Figure 5.2-2. Side channel, side slough, and upland slough lengths per mile of main channel by
geomorphic reach and Focus Area (F), non-Focus Area (NF), and total (T). ................ 174
Figure 5.3-1. Location of 2012 and 2013 flow routing cross-sections. ..................................... 175
Figure 5.3-2. Pre and post September 2012 flood channel comparison for project river mile’s
98.4, 101.4, 110.5, 113.6, 119.9, and 124.1. ................................................................... 176
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Figure 5.3-3. Pre and post September 2012 flood channel comparison for project river mile’s
126.8, 129.7, 134.3, 137.6, 140.0, 142.2, 145.7, and 152.1. ........................................... 177
Figure 5.3-4. Comparison of cross-sectional profiles collected in 2012 and 2013. ................... 178
Figure 5.3-5. Stage readings for mainstem Susitna River sites ESS10-ESS40 for available data
from June through October 2012. ................................................................................... 179
Figure 5.3-6. Stage readings for mainstem Susitna River sites ESS45-ESS80 for available data
from June through October 2012. ................................................................................... 180
Figure 5.3-7. Example mainstem Susitna River data at station ESS20 for 2012 and 2013. ...... 181
Figure 5.3-8. Monthly average flow for potential wet, average, and dry representative years
using a linear scale. ......................................................................................................... 182
Figure 5.3-9. Monthly average flow for potential wet, average, and dry representative years
using a log scale. ............................................................................................................. 183
Figure 5.4-1. Flow releases from the proposed Watana Dam site, input to the flow routing model
for the Pre-Project and Maximum Load Following OS-1 scenarios during calendar year
1984................................................................................................................................. 184
Figure 5.4-2. Examples of cross-sections established on the Susitna River in 2012 at PRM 173.1
on June 21, 2012 and PRM 80 on August 24, 2012. ...................................................... 185
Figure 5.4-3. Output from ADCP from one pass across the Susitna River at PRM 173.1 on June
21, 2012........................................................................................................................... 185
Figure 5.4-4. Longitudinal thalweg profile of the Susitna River extending from PRM 80.0 to
PRM 187.2 (Devils Canon is represented by the dashed red line). ................................ 186
Figure 5.4-5. Locations of flow measurements in the Susitna River in 2012, and classification of
flows as low, medium, or high based on concurrent measurements in the Susitna River at
Gold Creek (USGS Gage No. 15292000). ...................................................................... 187
Figure 5.4-6. Manning’s n channel roughness coefficients derived from steady-state calibration
of flow routing model for 88 cross-sections of the Susitna River surveyed in 2012. ..... 188
Figure 5.4-7. Flow hydrographs measured at 15-minute intervals by the U.S. Geological Survey
in the Susitna River at Sunshine (Gage No. 15292780), at Gold Creek (Gage No.
15292000), and above Tsusena Creek (Gage No. 15291700) during the week of August
11 to 17, 2012, when there were diurnal pulses associated with glacial melt. ............... 189
Figure 5.4-8. Flow hydrographs measured at 15-minute intervals by the U.S. Geological Survey
in the Chulitna River near Talkeetna (Gage No. 15292400) and in the Talkeetna River
near Talkeetna (Gage No. 15292700) during the week of August 11 to 17, 2012, when
there were diurnal pulses associated with glacial melt. .................................................. 190
Figure 5.4-9. Flow hydrographs measured at 15-minute intervals by the U.S. Geological Survey
in the Susitna River at Gold Creek (Gage No. 15292000) and above Tsusena Creek (Gage
No. 15291700, shifted forward by 6.4 hours) during the week of August 11 to 17, 2012.
......................................................................................................................................... 191
Figure 5.4-10. Ungaged lateral inflow hydrographs at 15-minute intervals to the Susitna River to
four reaches between Tsusena Gage and Sunshine Gage, August 11 to 17, 2012. ........ 192
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Figure 5.4-11. Comparison of measured versus simulated flow hydrographs in the Susitna River
at Gold Creek (USGS Gage No. 15292000) during the period from August 11 to August
17, 2012, when there were distinct diurnal flow fluctuations associated with glacial melt.
......................................................................................................................................... 193
Figure 5.4-12. Flow hydrographs measured at 15-minute intervals by the U.S. Geological
Survey in the Susitna River at Sunshine (Gage 15292780), at Gold Creek (Gage
15292000), and above Tsusena Creek (USGS 15291700) during the period from June 4 to
October 14, 2012. ............................................................................................................ 194
Figure 5.4-13. Flow hydrographs measured at 15-minute intervals by the U.S. Geological
Survey in the Chulitna River near Talkeetna (Gage No. 15292400) and in the Talkeetna
River near Talkeetna (Gage No. 15292700) during the period from June 4 to October 14,
2012................................................................................................................................. 195
Figure 5.4-14. Ungaged lateral inflow hydrographs at 15-minute intervals to the Susitna River to
four reaches between Tsusena Gage and Sunshine Gage during the period from June 4 to
October 14, 2012. ............................................................................................................ 196
Figure 5.4-15. Comparison of measured versus simulated flow hydrographs in the Susitna River
at Gold Creek (USGS Gage No. 15292000) during the period from June 4 to October 14,
2012................................................................................................................................. 197
Figure 5.4-16. Comparison of measured versus simulated flow hydrographs in the Susitna River
at Sunshine (USGS Gage No. 15292780) during the period from June 4 to October 14,
2012................................................................................................................................. 198
Figure 5.4-17. Illustration of 15-minute flow hydrograph, synthesized from available daily
flows. The synthesized 15-minute flow hydrograph does not account for potential diurnal
variation associated with glacial melt. ............................................................................ 199
Figure 5.4-18. Flow hydrographs synthesized at 15-minute intervals from daily flows reported
by the U.S. Geological Survey in the Susitna River at Sunshine (Gage No. 15292780), at
Gold Creek (Gage No. 15292000), and above Tsusena Creek (Gage No. 15291700)
during calendar year 1984. .............................................................................................. 200
Figure 5.4-19. Flow hydrographs synthesized at 15-minute intervals from daily flows reported
by the U.S. Geological Survey in the Chulitna River near Talkeetna (Gage No.
15292400) and in the Talkeetna River near Talkeetna (Gage No. 15292700) during
calendar year 1984. ......................................................................................................... 201
Figure 5.4-20. Ungaged lateral inflow hydrographs at 15-minute intervals to the Susitna River to
four reaches between Tsusena Gage (15291700) and Sunshine Gage (15292780) during
calendar year 1984. ......................................................................................................... 202
Figure 5.4-21. Predicted stage hydrographs in the Susitna River at Gold Creek (USGS Gage No.
15292000) under Pre-Project and Maximum Load Following OS-1 conditions during the
week of July 23 to July 29, 1984. Pre-Project conditions do not account for potential
diurnal fluctuations associated with glacial melt. ........................................................... 203
Figure 5.4-22. Predicted stage hydrographs in the Susitna River at Sunshine (USGS Gage No.
15292780) under Pre-Project and Maximum Load Following OS-1 conditions during the
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week of July 23 to July 29, 1984. Pre-Project conditions do not account for potential
diurnal fluctuations associated with glacial melt. ........................................................... 204
Figure 5.5-1. Map showing FA-104 (Whiskers Slough) with randomly selected habitat segments
and the location of each 2013 HSC sampling event within the Middle Segment of the
Susitna River, Alaska. ..................................................................................................... 205
Figure 5.5-2. Map showing FA-113 (Oxbow I) with randomly selected habitat segments and the
location of each 2013 HSC sampling event within the Middle Segment of the Susitna
River, Alaska................................................................................................................... 206
Figure 5.5-3. Map showing FA-115 (Slough 6A) with randomly selected habitat segments and
the location of each 2013 HSC sampling event within the Middle Segment of the Susitna
River, Alaska................................................................................................................... 207
Figure 5.5-4. Map showing FA-128 (Slough 8A) with randomly selected habitat segments and
the location of each 2013 HSC sampling event within the Middle Segment of the Susitna
River, Alaska................................................................................................................... 208
Figure 5.5-5. Map showing FA-138 (Gold Creek) with randomly selected habitat segments and
the location of each 2013 HSC sampling event within the Middle Segment of the Susitna
River, Alaska................................................................................................................... 209
Figure 5.5-6. Map showing FA-141 (Indian River) with randomly selected habitat segments and
the location of each 2013 HSC sampling event within the Middle Segment of the Susitna
River, Alaska................................................................................................................... 210
Figure 5.5-7. Map showing FA-144 (Slough 21) with randomly selected habitat segments and
the location of each 2013 HSC sampling event within the Middle Segment of the Susitna
River, Alaska................................................................................................................... 211
Figure 5.5-8. Average daily discharge as reported at the Gold Creek gage (USGS Gage No.
15292000) during each of the seven HSC sampling session (vertical gray bars) complete
during the summer of 2013 in the Middle River Segment of the Susitna River, Alaska.212
Figure 5.5-9. Example comparison of depth (top) and velocity (bottom) habitat suitability for
chum spawning based on utilization and preference, all normalized to have maximum
suitability of 1. ................................................................................................................ 213
Figure 5.5-10. Comparison of substrate habitat suitability for chum spawning based on
utilization and preference, all normalized to have maximum suitability of 1. ............... 214
Figure 5.5-11. Comparison of change in normalized water surface elevation among continuous
monitoring sites in FA-104 (Whiskers Slough) during February through April 2013. .. 214
Figure 5.5-12. Comparison of change in normalized water surface elevation among continuous
monitoring sites in FA-128 (Slough 8A) during March through early August 2013. .... 215
Figure 5.5-13. Water temperature recorded above the substrate surface and at intergravel depths
of 5 cm, 20 cm, and 35 cm at main channel (MC-50), side channel (WSC-30) and side
slough (CFSL-10) continuous monitoring sites in FA-104 (Whiskers Slough) during
February - April 2013. .................................................................................................... 216
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Figure 5.5-14. Water temperature recorded above the substrate surface and at intergravel depths
of 5 cm, 20 cm, and 35 cm at upland slough (SL3A-70) and side channel (SL3B-10,
WSC-10) continuous monitoring sites in FA-104 (Whiskers Slough) during February -
April 2013. ...................................................................................................................... 217
Figure 5.5-15. Water temperature recorded above the substrate surface and at intergravel depths
of 5 cm, 20 cm, and 35 cm at tributary (WC-10) and side slough (WS-20, WS-40)
continuous monitoring sites in FA-104 (Whiskers Slough) during February - April 2013.
......................................................................................................................................... 218
Figure 5.5-16. Comparison of continuous surface and intergravel water temperatures at side
channel (WSC-30), tributary (WC-10) and side slough (WSL-20) sites relative to change
in normalized water surface elevation at each site and at main channel site MC-50. .... 219
Figure 5.5-17. Instantaneous measurements of surface water temperature and specific
conductance recorded at sites in FA-104 (Whiskers Slough) during April 2013, by habitat
type. ................................................................................................................................. 220
Figure 5.5-18. Instantaneous measurements of surface water temperature and specific
conductance recorded at sites in FA-128 (Slough 8A) during April 2013, by habitat type.
Asterisks represent measurements of bank seepage. ...................................................... 221
Figure 5.5-19. Continuous intergravel dissolved oxygen and temperature data recorded at FA-
128 (Slough 8A) site SL8A-15 during March and April 2013. ...................................... 222
Figure 5.6-1. FA-104 (Whiskers Slough) showing fine and course mesh overlays, channel inlet
and outlet measurement locations, and alignment of 2013 calibration transects. ........... 223
Figure 5.6-2. FA-113 (Oxbow 1) showing fine and course mesh overlays, channel inlet and
outlet measurement locations, and alignment of 2013 calibration transects. ................. 224
Figure 5.6-3. FA-115 (Slough 6A) showing fine and course mesh overlays, channel inlet and
outlet measurement locations, and alignment of 2013 calibration transects. ................. 225
Figure 5.6-4. FA-128 (Slough 8A) showing fine and course mesh overlays, channel inlet and
outlet measurement locations, and alignment of 2013 calibration transects. ................. 226
Figure 5.6-5. FA-138 (Gold Creek) showing fine and course mesh overlays, channel inlet and
outlet measurement locations, and alignment of 2013 calibration transects. ................. 227
Figure 5.6-6. FA-141 (Indian River) showing fine and course mesh overlays, channel inlet and
outlet measurement locations, and alignment of 2013 calibration transects. ................. 228
Figure 5.6-7. FA-144 (Slough 21) showing fine and course mesh overlays, channel inlet and
outlet measurement locations, and alignment of 2013 calibration transects. ................. 229
Figure 5.6-8. Example 2-D hydraulic model output for use as input to 2-D habitat model. ..... 230
Figure 5.6-9. Screen shot of VB modeling showing potential configuration for parameters to be
used in the habitat modeling. .......................................................................................... 230
Figure 5.6-10. Example of tabular output from VB model for 2-D habitat analysis with new
column of computed suitability highlighted. .................................................................. 230
Figure 5.6-11. Example of graphic interface for VB model to provide preliminary display of
results used as an initial check on model output. ............................................................ 231
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Figure 5.6-12. Generalized data flow for 2-D habitat modeling in the middle river Focus Areas.
......................................................................................................................................... 231
Figure 5.6-13. Example of data dependencies and data flow for Effective Spawning/Incubation
Analysis in Middle River Focus Areas. .......................................................................... 232
Figure 5.6-14. Example of data flow from physical process and data analysis to the Effective
Spawning/Incubation Analysis. ...................................................................................... 233
Figure 5.6-15. Example of smaller spatial area analysis for effective spawning/incubation habitat
analysis (Note: the circled areas are for demonstration only and may not reflect actual
use). ................................................................................................................................. 234
Figure 5.6-16. Flow chart showing analysis sequence for effective spawning/incubation 2-D
habitat model highlighting groundwater dependency and analysis sequence. ............... 235
Figure 5.6-17. Example of groundwater data flow for use in Effective Spawning/Incubation
Analysis........................................................................................................................... 236
Figure 5.6-18. Example of groundwater upwelling data or trend supplied to 2-D habitat analysis.
......................................................................................................................................... 236
Figure 5.6-19. Example data analysis sequence for depth, scour (velocity), and water quality for
Effective Spawning/Incubation Analysis in Focus Areas. .............................................. 237
Figure 5.6-20. Example of other inputs from physical models for Effective Spawning/Incubation
Analysis........................................................................................................................... 238
Figure 5.6-21. Example of GIS tool output showing habitat suitability for an entire Focus Area.
......................................................................................................................................... 238
Figure 5.6-22. Example of GIS tool output showing depth for an entire Focus Area. .............. 239
Figure 6.3-1. Aerial photo of locations of cross-sectional data collected at PRM 124.1 of the
Susitna River 2012 and 2013. ......................................................................................... 240
Figure 6.3-2. Aerial photo of locations of cross-sectional data collected at PRM 137.6 of the
Susitna River in 2012 and 2013. ..................................................................................... 241
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APPENDICES
Appendix A: Hydrologic Methods
Appendix B: Biological Cues Study
Appendix C: Moving Boat ADCP Measurements
Appendix D: GINA Initial Study Report 8.5 Data Files
Appendix E: Tributary Gaging Site Schematics
Appendix F: Tributary Gaging Representative Site Photos
Appendix G: HSC Histogram Plots
Appendix H: Periodicity Tables
Appendix I: Lower River Hydraulic Model Calibration
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LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
ADCP Acoustic Doppler Current Profiler
ADF&G Alaska Department of Fish and Game
AEA Alaska Energy Authority
cfs cubic feet per second
CIRWG Cook Inlet Region Working Group
DO dissolved oxygen
DSS data storage system
EFC Environmental Flow Component
EFM Ecosystem Functions Model
FA focus area
FERC Federal Energy Regulatory Commission
fps feet per second
FSP Final Study Plan
ft/sec feet per second
GIS geographic information system
GPS global positioning system
HRM Historic River Mile
HSC Habitat Suitability Criteria
HSI Habitat Suitability Index
IFIM Instream Flow Incremental Methodology
IFS Instream Flow Study
IFS-FA Instream Flow Study – Fish and Aquatics (8.5)
IHA Indicators of Hydrologic Alteration
ISR Initial Study Report
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Abbreviation Definition
LiDAR Light Detection and Ranging
LR Lower River
LWD large woody debris
mg/L milligrams per liter
MHz megahertz
mph miles per hour
MR Middle River
MWH MWH Global
NMFS NOAA National Marine Fisheries Service
NTU nephelometric turbidity unit
OS Operating Scenario
QA/QC quality assurance/quality control
PDO Pacific Decadal Oscillation
PHABSIM Physical Habitat Simulation
ppm parts per million
PRM Project River Mile
REFDSS Riverine Environmental Flow Decision Support System
RIRP Railbelt Integrated Resources Plan
RM River Mile
RSP Revised Study Plan
RTK Real time kinematic
SOP Standard Operating Procedure
SPD Study Plan Determination
TM Technical Memorandum
TNC The Nature Conservancy
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Abbreviation Definition
TT Technical Team
TWG Technical Workgroup
USACE United States Army Corps of Engineers
USGS United States Geological Survey
USR Updated Study Report
WUA Weighted Usable Area
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EXECUTIVE SUMMARY
Fish and Aquatics Instream Flow Study 8.5
Purpose The objective of the Fish and Aquatics Instream Flow Study (IFS) is to
characterize and evaluate the potential operational flow-induced effects of the
proposed Project on fish habitat below the proposed Project dam. The focus
of implementation of this study is on establishing a set of analytical
tools/models based on site-specific channel and hydraulic data that can be
used for defining existing conditions (i.e., without Project) and how these
resources and processes will respond to alternative Project operational
scenarios.
Status The IFS study, which consists of eight study components, was initiated in
2013 in accordance with the Study Plan and resulted in the selection of study
areas and study sites that are being used across resource disciplines, as well as
the collection of substantial field data (including completion of pilot winter
fish studies) that will be used in evaluating flow related effects of the Project
on fish habitats. In addition, Version 1 of the Open-water Flow Routing
Model was developed and used by a number of resource disciplines for
planning studies and defining the downstream extent of Project effects. The
IFS study team is currently analyzing data, developing habitat – flow models,
refining the Open-water Flow Routing Model, and preparing to continue data
collection efforts for the next year of study.
Study
Components
The IFS study includes the following components as described in the Study
Plan:
1. IFS Analytical Framework
2. River Stratification and Study Area Selection
3. Hydraulic Routing and Operations Modeling
4. Hydrologic Data Analysis
5. Habitat Suitability Criteria Development
6. Habitat-Specific Model Development
7. Temporal and Spatial Habitat Analyses
8. Instream Flow Study Integration
2013 Variances While land access was not available for the three upper Focus Areas adjacent
to Cook Inlet Regional Working Group (CIRWG) lands in 2013, this was not
considered a variance because this study was designed to collect data over
multiple years. Alaska Energy Authority (AEA) implemented the methods as
described in the Study Plan with the exception of the following variances:
The Study Plan indicated 13 mainstem water-level recording stations would
be maintained in 2013 (RSP Section 8.5.4.3.1). After calibration and
validation of the Version 1 Open-water Flow Routing Model, and in response
to land owner access issues, five stations were not maintained in 2013 (ISR
Study 8.5, Section 4.4.2).
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Fish and Aquatics Instream Flow Study 8.5
The Study Plan indicated continuous stage measurements would be collected
in the mainstem (RSP Section 8.5.4.3.1). Due to ice damage, flooding and
land access issues, some short and long-term data gaps of water stage exist for
eight hydrology locations (ISR Study 8.5, Section 4.3.2).
The Study Plan indicated continuous gaging would be installed at Fog Creek
and Portage Creek (RSP Section 8.5.4.4.1.1). Due to land access issues, these
were not installed in 2013 (ISR Study 8.5, Section 4.3.2).
The Study Plan indicated that specific representative years and the duration of
the continuous flow record would be selected by AEA in consultation with
the TWG in Q3 2013 (RSP Section 8.5.4.4.1.2). This selection was discussed
at the November 13-15, 2013 Riverine Modelers meeting and Q4 2013 TWG
meeting. (ISR Study 8.5, Section 4.3.2).
The Study Plan indicated that hydrologic parameters for IHA analysis would
be developed in consultation with the TWG in Q3 2013 and interim results of
IHA-type analysis would be presented in the ISR (RSP Section 8.5.4.4.1.3).
A description of the initial proposed methodology is provided in ISR Study
8.5, Section 5.3, and will undergo continued discussion and coordination with
the TWG (ISR Study 8.5, Section 4.3.2).
The Study Plan indicated that HSC sample sites would be stratified and
randomly selected from within the Middle River Segment and Lower River
Segment (RSP Section 8.5.4.5.1.1.3). Due to access restrictions, the Middle
River Segment was limited to habitat areas between Portage Creek and Three
Rivers Confluence. Due to flow related delays in completing the habitat
mapping surveys and the desire to focus sampling in 2013 on the Middle
River, the Lower River segment was not sampled (ISR Study 8.5, Section
4.5.2).
The Study Plan indicated spawning redd dimensions would be collected (RSP
Sections 8.5.4.5.1.1.4 and 8.5.4.5.1.1.5). These were collected in 2012 but in
2013 deemed unnecessary for developing evaluation metrics (ISR Study 8.5,
Section 4.5.2).
The Study Plan indicated that substrate size (dominant, sub-dominant, and
percent dominant) would be characterized in accordance with a Wentworth
grain size scale modified to reflect English units (RSP Sections 8.5.4.5.1.1.4,
8.5.4.5.1.1.5, 8.5.4.5.1.1.6.1, and 8.5.4.6.1.2.4). Field personnel found it
impracticable to attempt to accurately differentiate gravel composition into
three size classes in turbid water conditions and used two instead (ISR Study
8.5, Section 4.5.2).
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Fish and Aquatics Instream Flow Study 8.5
The Study Plan indicated that location in water column, focal point and mean
column velocity would be measured using a Price AA current meter (RSP
Section 8.5.4.5.1.1.6.1). Most fish captures occurred using electrofishing,
seining or a combination of the two methods which precluded the
identification of fish focal point position within the water column (ISR Study
8.5, Section 4.5.2).
The Study Plan indicated that mesohabitat type would be recorded for fish
observation/capture points (RSP Section 8.5.4.5.1.1.6.1). After the
mesohabitat mapping task is complete, GIS data layers containing the
location of HSC fish use observations will be used (ISR Study 8.5, Section
4.5.2).
The Study Plan indicated that field surveys would be conducted at potential
stranding and trapping areas on an opportunistic basis following up to three
flow reduction events during 2013 (RSP Section 8.5.4.5.1.2.2). The need for
these studies will be discussed with the TWG..
The Study Plan indicated that 2012-2013 winter study results would be
distributed to the TWG by Q3 2013 (RSP Section 8.5.4.5.1.2.1). The results
will be distributed to the TWG in 2014 (ISR Study 8.5, Section 4.5.2).
The Study Plan indicated that macroinvertebrate sampling would occur at six
stations, each with three sites (one mainstem site and two off-channel sites
associated with the mainstem site), for a total of 18 sites (RSP Section
8.5.4.5.1.2.3). This sampling occurred at five stations on the Susitna River,
each station with three to five sites (establishing sites at all macrohabitat types
present within the station), for a total of 20 sites (ISR Study 8.5, Section
4.5.2).
The Study Plan indicated the Deshka River Chinook salmon and Yentna
River sockeye salmon datasets would be examined for flow-dependent
biological cues (RSP Section 8.5.4.5.1.3). Mainly due to lack of the
necessary data, the Deshka River and the Yentna River were not used for this
study. Through further discussions with ADF&G, the Taku River and Stikine
River Chinook salmon stocks were selected (ISR Study 8.5, Section 4.5.2).
The Study Plan indicated that additional variables would be compared to fish
distribution and abundance: surface flow and groundwater exchange fluxes,
dissolved oxygen (intergravel and surface water), macronutrients, temperature
(intergravel and surface water), pH, dissolved organic carbon, alkalinity, and
Chlorophyll-a. Depending on these relationships, additional HSC preference
curves may be needed (FERC 2013c [FERC April 1 SPD, page B-85]). Most
of the data necessary to complete this analysis is still being processed and/or
undergoing quality assurance checks and is not available at this time (ISR
Study 8.5, Section 4.5.2).
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Fish and Aquatics Instream Flow Study 8.5
The Study Plan indicated that five tributary mouths, including Sheep Creek
and Caswell Creek, would be investigated as part of the Lower River studies
(R2 2013b [Technical Memorandum, Selection of Focus Areas and Study
Sites in the Middle and Lower Susitna River for Instream Flow and Joint
Resource Studies – 2013 and 2014]). Two of the five sites identified for
study in 2013 were not completed and were deferred to the next study year in
order to evaluate the effectiveness of the model outputs from the other three
sites and evaluate the need for additional sites (ISR Study 8.5, Section 4.6.2).
The Study Plan indicated that an evaluation of the representativeness of the
Lower River study areas was to occur by Q4 2013 (R2 2013b [Technical
Memorandum, Selection of Focus Areas and Study Sites in the Middle and
Lower Susitna River for Instream Flow and Joint Resource Studies – 2013
and 2014]). This task is scheduled to be completed before the start of the next
field data collection period (ISR Study 8.5, Section 4.6.2).
The Study Plan indicated that the final approach and details concerning
methods for conducting temporal analysis and Project operational scenarios
would be discussed with the TWG in Q4 2013 (RSP Section 8.5.4.7.1.1). The
general approaches to be used for the spatial analysis of the fish habitat
models and the temporal analysis for the different resource models were
discussed as part of the November 13-15, 2013 Instream Flow Study
Technical Team Riverine Modelers meeting. More details concerning these
methods are provided in this ISR and AEA is planning on finalizing the
methods in 2014, in accordance with the Study Plan schedule, and
demonstrating the application of the methods during the Proof of Concept
TWG meeting in 2014 (ISR Study 8.5, Section 4.7.2).
Steps to
Complete the
Study
As explained in the cover letter to this draft ISR, AEA’s plan for completing
this study will be included in the final ISR filed with FERC on June 3, 2014.
Highlighted
Results and
Achievements
In 2013, the major field efforts were associated with collection of HSC/ HSI
fish habitat data (winter and open-water periods), mainstem Susitna and
tributary hydrology data, bathymetry and topographic data, and
characterization of substrates.
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Fish and Aquatics Instream Flow Study 8.5
HSC/HSI activities included the selection of target species and life stages,
development of draft HSC curves using existing information, selection of
HSC sampling locations, collection of microhabitat use and availability data
for the target fish species, development of histograms displaying frequency of
use for different microhabitat variables, and preliminary development of
microhabitat preference curves. A total of 68 HSC data collection sites were
randomly selected for collection of HSC field data to quantify microhabitat
use by spawning and freshwater ‘rearing’ (juvenile resident or anadromous
fish) or ‘holding’ (adult resident fish) life stages of target fish species. During
each survey, both microhabitat utilization (water depth, velocity, substrate
composition, turbidity, and cover) and availability data were collected during
each sampling event. Habitat measurements were collected for four different
life history stages (spawning, juvenile, fry, and adult) and twelve different
fish species: Chinook, sockeye, chum, coho, and pink salmon; rainbow trout;
Arctic grayling; Arctic lamprey; Dolly Varden char; whitefish; longnose
sucker; and burbot. A total of 1,433 observations of site-specific habitat use
was recorded during 2013 HSC surveys of the Middle Susitna River. A total
of 3,297 measurements of habitat availability was collected from within each
of the seven Focus Areas and from additional areas located outside of the
Focus Areas. Pilot winter studies were also initiated during 2012–2013 to
monitor water quality and stage conditions at salmon spawning locations and
to record fish habitat use.
Hydrology data collected in 2012 and 2013 were used in development of
Version 1 of the Open-water Flow Routing Model. Hydrology data collection
included streamflow and/or water surface elevation measurements at 13
mainstem sites in 2012, 8 mainstem sites in 2013, and 13 tributary sites in
2013. Streamflow, water surface elevation, or bathymetry data were also
collected at 145 mainstem transects over both the 2012 and 2013 field
seasons. These data were used in refining the Open-water Flow Routing
Model.
Bathymetric, ADCP, and substrate characterization surveys were completed
for seven of the ten Focus Areas; data will be used in development of a 2-D
hydraulic model that will be used in a PHABSIM related analysis to develop
habitat-flow relationships for target fish species and life stages. Surveys in
the Lower River Segment consisted of the collection of field data at 1-D
single transect locations that will be used for defining habitat-flow
relationships. Lower River field data collection during 2013 consisted of
three site visits (June, August and September) to coincide with high, moderate
and low flow conditions.
Analysis of data collected in 2013 is ongoing and is focused on development
of different models that will be used for evaluating fish habitat-flow
relationships, as well as developing plans for continuing data collection and
analysis for the next year of study.
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1. INTRODUCTION
On December 14, 2012, AEA filed with the Federal Energy Regulatory Commission (FERC or
Commission) its Revised Study Plan (RSP), which included 58 individual study plans (AEA
2012). Included within the RSP was the Fish and Aquatics Instream Flow Study (FA-IFS),
Section 8.5. RSP Section 8.5 focuses on establishing an understanding of important biological
communities and associated habitats, and of the hydrologic, physical, and chemical processes in
the Susitna River that directly influence those resources. RSP Section 8.5 also described the
study methods that will be used to evaluate Project effects, including the selection of study sites,
collection of field data, data analysis, and modeling.
Following submittal of the RSP, the FERC issued a Study Plan Determination (SPD) Schedule
on January 17, 2013 (FERC 2013a) that specified deliverables of three IFS-related analyses: 1)
results of the Open-water Flow Routing Model; 2) identification of all proposed Focus Areas
with a description of habitat units within the Focus Areas for all aquatic studies to be
implemented in the Middle Susitna River; and 3) identification of final Focus Areas for 2013
Middle and Lower River studies. Technical Memoranda (TM) pertaining to the first two
deliverables were prepared and submitted to the FERC on January 31, 2013 (R2 Resource
Consultants, Inc. [R2] et al. 2013; R2 2013a). The Final Middle and Lower River Focus Areas
TM was filed with FERC on March 1, 2013 (R2 2013b).
On April 1, 2013, FERC issued its Study Plan Determination (April 1 SPD) for 14 of the 58
studies approving RSP Section 8.5 with modifications (FERC 2013b).
In its April 1 SPD, FERC recommended the following:
Microhabitat Types, HSC and HSI Development
- We recommend that AEA file with the Initial Study Report, a detailed evaluation of the
comparison of fish abundance measures (e.g., number of individuals by species and age
class) with specific microhabitat variable measurements where sampling overlaps, to
determine whether a relationship between a specific microhabitat variable and fish
abundance is evident. We expect the majority of locations where fish sampling and the
eight additional microhabitat variable sampling efforts would overlap at a scale where
they could be related would occur in focus areas where these sampling efforts are
concentrated. If results from these initial comparisons indicate strong relationships may
exist between a specific microhabitat parameter and fish abundance for a target species
and life stage, expanded sampling may be necessary in 2014 to investigate these
microhabitat relationships further. Accordingly, we recommend that AEA include in the
evaluation to be filed with the Initial Study Report, any proposals to develop HSC curves
for any of the 8 additional parameters as part of the 2014 study season.
Upwelling and Downwelling
- We recommend that AEA test the feasibility of measuring vertical hydraulic gradient as
a site-specific microhabitat variable using field measurements, and if determined feasible
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and effective at describing upwelling, incorporate the methods into the site-specific HSC
development process. The results of the feasibility test (regardless of whether a feasible
or infeasible finding is made) should be summarized in the Initial Study Report.
Water Quality Monitoring at Salmon Spawning Locations
- We recommend that AEA monitor temperature, dissolved oxygen, and water level
monitoring data at one or more select Chinook, pink, and coho spawning locations within
Middle River focus areas.
Instream Flow Study Areas and Study Sites
- We recommend that AEA: (1) consult with the TWG and select an appropriate focus
area within MR-2 to eliminate from the study; (2) consult with the TWG and establish an
additional focus area in geomorphic reach MR-7 that is sufficient for conducting
interdisciplinary studies, possibly near Lower McKenzie Creek or below Curry on old
Oxbow II; and (3) file a detailed description of the changes to the proposed focus area
locations in MR-2 and MR-7 by May 31, 2013, and include in the filing documentation of
consultation with NMFS, FWS, and Alaska DFG, including how the agency comments
were addressed.
In accordance with the April 1 SPD, an Instream Flow Technical Team meeting was held on
April 26, 2013, and the AEA conferred with the TWG representatives concerning the changes to
the Focus Area locations. On May 31, 2013, the AEA filed with FERC the Adjustments to
Middle River Focus Areas TM (R2 2013c), providing the details requested in the April 1 SPD.
Information in the Adjustments to the Middle River Focus Areas TM provides supplemental
detail concerning the final selection of Focus Areas presented in the RSP and the Middle and
Lower River Focus Areas TM filed with FERC on March 1, 2013 (R2 2013b).
Following the first study season, FERC’s regulations for the Integrated Licensing Process (ILP)
require AEA to “prepare and file with the Commission an initial study report describing its
overall progress in implementing the study plan and schedule and the data collected, including an
explanation of any variance from the study plan and schedule.” (18 CFR 5.15(c)(1)) This Initial
Study Report on the Fish and Aquatic Instream Flow Study has been prepared in accordance
with FERC’s ILP regulations and details AEA’s status in implementing the study, as set forth in
the FERC-approved RSP and as modified by FERC’s April 1 SPD, the Open-water Flow
Routing Model Technical Memo (R2 et al. 2013), the Final Middle and Lower River Focus
Areas TM (R2 2013b), and the Adjustments to Middle River Focus Areas TM (R2 2013c)
(collectively referred to herein as the “Study Plan”).
2. STUDY OBJECTIVES
The goal of the Fish and Aquatics Instream Flow Study (FA-IFS) 8.5 and its component study
efforts is to provide quantitative indices of existing aquatic habitats that enable a determination
of the effects of alternative Project operational scenarios. The study objectives are established in
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RSP Section 8.5.1.2. Specific FA-IFS Study Plan objectives and associated companion studies
include the following:
1. Map the current aquatic habitat in main channel and off-channel habitats of the Susitna
River affected by Project operations. This objective will be completed as part of the
Characterization of Aquatic Habitats Study (Study 9.9) (Figure 2-1).
2. Select study areas and sampling procedures to collect data and information that can be
used to characterize, quantify, and model mainstem and lateral Susitna River habitat
types at different scales. This objective will be completed via a collaborative process
with the other resource studies (Riparian Instream Flow [Study 8.6], Groundwater [Study
7.5], Geomorphology [Studies 6.5 and 6.6], Water Quality [Studies 5.5 and 5.6], and Fish
and Aquatics studies), and is described in ISR Study 8.5, Section 4.
3. Develop a mainstem Open-water Flow Routing Model that estimates water surface
elevations and average water velocity along modeled transects on an hourly basis under
alternative operational scenarios. See ISR Study 8.5, Sections 4.4 and 5.3.
4. Develop site-specific Habitat Suitability Criteria (HSC) and Habitat Suitability Indices
(HSI) for various species and life stages of fish for biologically relevant time periods
selected in consultation with the TWG. Criteria will include observed physical
phenomena that may be a factor in fish preference (e.g., depth, velocity, substrate,
embeddedness, proximity to cover, groundwater influence, turbidity). If study efforts are
unable to develop robust site-specific data, HSC/HSI will be developed using the best
available information and selected in consultation with the TWG. See ISR Study 8.5,
Sections 4.5 and 5.5.
5. Develop integrated aquatic habitat models that produce a time series of data for a variety
of biological metrics under existing conditions and alternative operational scenarios.
These metrics may include (but are not limited to) the following:
• Water surface elevation at selected river locations
• Water velocity within study areas subdivisions (cells or transects) over a range of
flows during seasonal conditions
• Length of edge habitats in main channel and off-channel habitats
• Habitat area associated with off-channel habitats
• Clear water area zones
• Effective spawning and incubation habitats
• Varial zone areas
• Frequency and duration of exposure/inundation of the varial zone at selected river
locations
• Habitat suitability indices
See ISR Study 8.5, Sections 4.6 and 5.6.
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6. Evaluate existing conditions and alternative operational scenarios using a hydrologic
database that includes specific years or portions of annual hydrographs for wet, average,
and dry hydrologic conditions and warm and cool Pacific Decadal Oscillation (PDO)
phases. See ISR Study 8.5, Sections 4.3 and 5.4.
7. Coordinate instream flow modeling and evaluation procedures with complementary study
efforts, including Riparian Instream Flow (Study 8.6), Geomorphology (Studies 6.5 and
6.6), Groundwater (Study 7.5), Baseline Water Quality (Study 5.5), Fish Passage Barriers
(Study 9.12), and Ice Processes (Study 7.6) (see Figure 2-1).
8. Develop a Decision Support System-type framework to conduct a variety of post-
processing comparative analyses derived from the output metrics estimated under aquatic
habitat models. These include (but are not limited to) the following:
• Seasonal juvenile and adult fish rearing
• Habitat connectivity
• Spawning and egg incubation
• Juvenile fish stranding and trapping
• Ramping rates
• Distribution and abundance of benthic macroinvertebrates
See ISR Study 8.5, Sections 4.8 and 5.8.
3. STUDY AREA
The IFS program is focused on addressing flow-related effects of Project operations downstream
of the Watana Dam (PRM 187.1). As established in the Study Plan, the Susitna River is
characterized into three segments (Figure 3-1). The overall study area of the IFS includes the
two lower segments of the river: the Middle River Segment which extends from PRM 187.1
downstream to the Three Rivers Confluence at PRM 102.4 (Figure 3-2) and the Lower River
Segment which extends from the Three Rivers Confluence to Cook Inlet (Figure 3-3). These
river segments are described in ISR Study 8.5, Section 4.2.
4. METHODS
Evaluation of potential Project effects to Middle and Lower river habitats will consist of the
following components:
• IFS Analytical Framework (ISR Study 8.5, Section 4.1)
• River Stratification and Study Area Selection (ISR Study 8.5, Section 4.2)
• Hydraulic Routing (ISR Study 8.5, Section 4.4)
• Hydrologic Data Analysis (ISR Study 8.5, Section 4.3)
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• Habitat Suitability Criteria Development (ISR Study 8.5, Section 4.5)
• Habitat-Specific Model Development (ISR Study 8.5, Section 4.6)
• Temporal and Spatial Habitat Analyses (ISR Study 8.5, Section 4.7)
• Instream Flow Study Integration (ISR Study 8.5, Section 4.8)
Details concerning each of these components including proposed methodologies are provided
below.
4.1. IFS Analytical Framework
4.1.1. Methodology
AEA implemented the methods as described in this section of the Study Plan with no variances.
The Instream Flow Study (IFS) is designed to characterize the existing, unregulated flow regime
and the relationship of instream flow to riparian and aquatic habitats under alternative
operational scenarios. The instream flow framework is designed to integrate riverine processes,
including geomorphology, ice processes, water quality, and groundwater-surface water
interactions to quantify changes in indicators used to measure the integrity of aquatic resources.
Figure 4.1-1 depicts the analytical framework of the IFS, which will be used to evaluate
unregulated flows and alternative operational scenarios under average, wet, dry, and warm and
cool hydrologic conditions. These conditions are defined further in ISR Study 8.5, Section 5.3.
The overall framework includes analytical steps that are consistent with those described in the
Instream Flow Incremental Methodology (IFIM) (Stalnaker et al. 1995), which will be used as a
guide for completing the instream flow evaluation for the Project. The framework also generally
follows the analytical steps that were applied for evaluating the effects of the proposed 1980s
Susitna Hydroelectric Project on aquatic biota (Entrix 1986).
The proposed Project will alter streamflow and the transport of sediment and large woody debris
(LWD) downstream of the proposed dam site. These stressors will affect channel morphology
and the quantity, quality, and timing of downstream habitats. The IFS framework will be used to
assess Project effects on downstream habitats under existing channel conditions, and will also
provide for the evaluation of alternative operational scenarios under estimated future channel
conditions. Changes in flow, ice processes, and sediment and LWD transport may cause channel
degradation, avulsion, and other channel changes and may contribute to changes in the
distribution and abundance of various habitat units (see page 2 of Figure 4.1-1). Integration of
the Geomorphology studies (ISR Study 6.5 and 6.6) and other riverine process studies will allow
future channel change to be evaluated at future time steps (e.g., current, 25 years, 50 years)
within the expected term of the license.
Figure 4.1-1 depicts the analytical framework of the IFS that included for 2013 the initial
development of a number of resource specific models. These included the Reservoir Operations
Model that will be used to generate Project flow releases under alternative operational scenarios.
The Reservoir Operations Model (see ISR Study 8.5, Section 4.4) will provide input data to the
mainstem Open-water Flow Routing Model (see ISR Study 8.5, Section 4.4) and ice processes
models (ISR Study 7.6) that will be used to predict hourly flow and water surface elevations at
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multiple downstream locations, taking into account accretion and flow attenuation. Coincident
with the development of the Open-water Flow Routing Model, a series of biological and riverine
process studies was initiated in 2013 to supplement the information collected in the 1980s, as
necessary to assess the temporal and spatial relationships between riverine and biological
functions. These analyses are being used to develop a series of flow-sensitive models that will
quantify Project effects on indicators for each aquatic and riparian resource.
Resource and process effects will be location- and habitat-specific (e.g., responses are expected
to be different in sloughs versus main channel versus split channel versus tributary delta versus
riparian habitats), but there will also be a cumulative analysis that translates effects throughout
the Susitna River. The IFS framework provides for the analysis of indicators that estimate flow-
habitat response patterns for different species and life stages of fish and other aquatic biota.
These models represent core tools that will be used for assessing changes in aquatic habitats
under alternative operational scenarios. Additionally, a fish passage analysis (Study 9.12) will
be used to develop the relationship between main channel flow and connectivity with side
channel and off-channel areas. Data collection and modeling for Study 9.12 will be coordinated
with the FA-IFS study, Fish and Aquatics studies, and Geomorphology studies 6.5 and 6.6 to
ensure identification of potential fish passage barriers and hydraulic control points (see Figure 2-
1).
Alternative operational scenarios will likely affect habitats and riverine processes on both a
spatial and temporal scale. The habitat and process models will therefore be spatially discrete
(e.g., by Focus Area, reach, and segment) and yet able to be integrated to allow for a holistic
evaluation by alternative operational scenario. This will allow for an Integrated Resource
Analysis of multiple resources for each operational scenario and provides feedback, leading to
potential modifications of alternative operational scenarios (see ISR Study 8.5, Section 4.8).
The IFS framework (Figure 4.1-1) represents a measurement-oriented approach to assessing the
relationship of hydrologic and geomorphic variables to the biological and ecological resources of
concern. Stressors associated with Project effects include changes in the volume, timing, and
quality of instream flow, and changes in ice processes and in sediment and large woody debris
transport. The effects of these stressors on resources of concern will be evaluated using
indicators that measure changes in habitat suitability, quality, and accessibility. Reference
conditions establish the range of variation for each indicator and are defined by analysis of
unregulated flows under average, wet, and dry hydrologic conditions and warm and cool Pacific
Decadal Oscillation phases. Project effects under alternative operational scenarios are defined as
departures from the reference conditions. The IFS framework provides the tools to identify
operational scenarios that balance resource interests and quantify any loss of aquatic resources
and their habitats that result from Project operations.
As part of the analytical framework, an Instream Flow Study–Technical Workgroup (IFS-TWG)
was formed consisting of technical representatives. The IFS-TWG has provided and will
continue to provide input into specific study design elements pertaining to the IFS, including
selection of study areas, selection of methods and models, selection of HSC criteria, review and
evaluation of hydrology and habitat-flow modeling results, and review of Project
operations/habitat modeling results. For example, a TWG meeting occurred on September 14,
2012, and focused on the study area selection process. Since then, IFS-TWG meetings have
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occurred on October 24, 2012, February 7, 2013, February 14, 2013, March 27, 2013, June 25,
2013, September 24, 2013, and December 3, 2013. In addition, several IFS-Technical Team
(IFS-TT) meetings have occurred outside of the TWG meetings as a means to address specific
technical questions or issues central to IFS-related studies. For example, IFS-TT meetings have
been held to discuss final selection of study sites (April 26, 2013), model selection (May 13,
2013), HSC/HSI sampling approaches (May 17, 2013 and June 11, 2013), and the integration of
resource models (November 13-15, 2013). A site visit and methods review was conducted with
TWG members on October 3-4, 2012. Results of the IFS-TT meetings are reported back to the
larger TWG.
4.1.2. Variances
AEA implemented the methods as described in this section of the Study Plan with no variances.
4.2. River Stratification and Study Area Selection
AEA implemented the methods as described in the Study Plan with the exception of variances
explained below (ISR Study 8.5, Section 4.2.2).
4.2.1. Methodology
4.2.1.1. River Stratification
The proposed Project would affect flows in mainstem and off-channel habitats in the Susitna
River downstream of the dam site at PRM 1 187.1. Two segments of the river are encompassed
within this 187.1-mile section:
• Middle River Segment – Susitna River from Watana Dam site to confluence of
Chulitna and Talkeetna rivers (Three Rivers Confluence) (PRM 187.1 to PRM 102.4)
• Lower River Segment – Susitna River extending below Three Rivers Confluence to
mouth (PRM 102.4 to PRM 0)
The Middle River Segment represents the section of river below the proposed Project dam that is
expected 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
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 that 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 line 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.
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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. 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
of the Susitna River at its mouth.
In order to characterize the existing and proposed flow regimes and potential Project-induced
impacts to riverine habitats and organisms, the Susitna River was initially stratified into
geomorphic reaches based in part on channel type, gradient, confinement, bed material, and
tributary confluences.
This analysis was completed for both the Middle River and Lower River segments, confirming
distinct variations in geomorphic attributes (e.g., channel gradient, confinement, channel
planform types, and others) (see ISR Study 6.5; and Tetra Tech 2013b). That analysis resulted in
the classification of the Middle River Segment into eight geomorphic reaches (Table 4.2-1, and
Figure 3-2) and six geomorphic reaches in the Lower River Segment (Figure 3-3).
Further refinements to the stratification system were applied based on discussions during the
August 16, 2012, September 14, 2012, October 2, 2012, February 14, 2013, and March 27, 2013,
TWG meetings, and two interdisciplinary team meetings that were focused on study area
selection and habitat mapping. This resulted in a more refined hierarchical stratification system
that scales from relatively broad to more narrowly defined categories as follows:
Segment →
Geomorphic Reach→
Macrohabitats (Mainstem, Off-channel, Tributary)→
Mesohabitats (Mainstem, Off-channel and Tributary)
The highest level category is termed Segment and refers to the Middle River Segment and the
Lower River Segment. The Geomorphic Reach level is next and consists of the eight categories
(MR-1 through MR-8) for the Middle River Segment and six categories (LR-1 through LR-6) for
the Lower River Segment (see Table 4.2-1 and ISR Study 6.5). 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
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Macrohabitat 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 (Table 4.2-2). Major categories and sub-categories under this level include: 1)
Mainstem Habitats consisting of Main Channel, Split Main Channel, Multiple Split Main
Channel, Side Channel, and Tributary Mouth (consisting of the segment of the tributary
influenced by mainstem flow; 2) Off-channel Habitats that include Side Slough and Upland
Slough; and 3) Tributary Habitats consisting of single channel, split channel, and channel
complex. The next level in the hierarchy is Mesohabitats, which for the Mainstem and Off-
channel classifies habitats into categories of Rapid, Riffle, Pool, Run/Glide, Clearwater plume,
Backwater, and Beaver Complex; and for Tributaries classifies habitats into Falls, Cascade,
Chute, Rapid, Boulder Riffle, Riffle, Run/glide, Pool (includes four subtypes), Beaver pond,
Alcove, and Percolation channel. These are more fully described in ISR Study 9.9.
The mesohabitat level of classification is currently limited to the main channel and tributary
mouths for which the ability to delineate these features was possible via aerial imagery and
videography. Mesohabitat mapping in side channel and slough habitat types and in six
tributaries of the Middle River Segment requires field surveys, which were initiated in 2013 (see
ISR Study 9.9). These field surveys were also designed to ground-truth and evaluate the
“classification type designations” that were made in 2013 and were based on remote aerial
imagery (see ISR Study 9.9).
Overall, the goal of the stratification step was to define segments/reaches with effectively similar
characteristics where, ideally, repeated replicate sampling would result in parameter estimates
with similar statistical distributions. The stratification/classification system described above was
designed to provide sufficient partitioning of sources of variation that can be evaluated through
focused study efforts that target each of the habitat types, and from which inferences concerning
habitat–flow responses in unmeasured sites can ultimately be drawn.
4.2.1.2. Selection of Study Areas/Study Sites
The selection of study areas/study sites differed between the Middle River Segment and Lower
River Segment. Because Project operations are anticipated to affect the Middle River Segment
the greatest, the selection of study areas and study sites within that segment received
considerable attention and review with the TWG. The selection of study sites within the Lower
River Segment was made subsequent to completion and review of the Open-water Flow Routing
Model (R2 et al. 2013) and other hydrologic analysis that was presented and discussed during the
February 14, 2013, TWG meeting. The site selection process for the Lower River Segment was
less intense than for the Middle River Segment and concentrated on establishing habitat-flow
relationships within visually determined representative sections of the river as well as selected
side channels, side sloughs, and tributary mouths that were repeatedly used by fish as noted in
the 1980s studies.
4.2.1.2.1. Middle River Study Area/Study Site Selection
In general (as noted by Bovee 1982), there are three characteristic approaches to instream flow
studies that pertain to site selection, and which were considered for application in the Middle
River Segment. These are representative sites/areas, critical sites/areas, and randomly selected
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sites/areas, and all three were employed to some degree in the selection of study areas and study
sites.
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 applied fairly readily 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 is 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, results of the aerial-based imagery habitat mapping of
the Middle River Segment were completed and analyzed (HDR 2013) (see ISR Study 8.5,
Section 5.2).
Critical Sites
Critical sites are those where available knowledge indicates that either i) a sizable fraction of the
target fish population relies on a specific location; ii) a particular habitat type(s) is (are) highly
important biologically; or iii) a particular habitat type is well known to be influenced by flow
changes in a characteristic way, and the decision is made to focus on those areas. 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. This information
factored directly into the selection of certain side channel/side slough/upland slough complexes.
Critical sites or areas are typically selected assuming that 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 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. This was likewise considered and resulted in the incorporation of
other off-channel habitats (i.e., habitats for which nothing was known regarding fish use or for
which previous studies indicated little fish use) into the overall study areas.
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
dataset: the greater the number of clusters, the greater the potential number of sites. Strict
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random sampling was therefore not considered applicable for evaluating off-channel habitats and
sloughs where the morphology of multiple channels varies substantially and in complex ways
within and across sites. However, random sampling was applied with respect to selection of
mainstem habitat types for HSC sampling (see ISR Study 8.5, Section 4.5) and fish distribution
and abundance sampling (see ISR Study 9.6).
Focus Areas
During the September 11, 2012, TWG meeting, the concept of “intensive study areas” was
introduced and discussed relative to sampling the Middle River Segment. This concept evolved
around the realization that a prerequisite to determining the effects of Project development and
operations on the Susitna River is the need to first develop an understanding of the basic
physical, chemical, and ecological processes of the river, their interrelationships, and their
relationships with flow. 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;
therefore, major emphasis was placed on selecting those specific locations, termed Focus Areas.
The Focus Area concept represents a combination of all three of the study site selection methods
described above, inasmuch as 1) the areas contain habitat types representative of other areas; 2)
the areas include certain habitat types repeatedly used by fish and therefore can be considered
“critical areas”; and 3) sampling of certain habitat types within the areas is being completed via
random sampling. As a corollary to the Focus Area approach, it was also reasoned there would
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 used for the Middle River Segment
represents a combination of both approaches.
Selection of Focus Areas
AEA’s interdisciplinary water resources team identified ten candidate Focus Areas using a
systematic review of aerial imagery within each of the Geomorphic Reaches (MR-1 through
MR-8) for the entire Middle River Segment (Table 4.2-3). Selection criteria for the Focus Areas
considered the following:
• All major habitat types (main channel, side channel, side slough, upland slough,
tributary delta) will be sampled within each geomorphic reach. All major habitat
types (main channel, side channel, side slough, upland slough, tributary mouth, clear
water plume) within the selected geomorphic reaches will be sampled.
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• At least one (and up to three) Focus Area(s) that is/are representative of other areas
will be studied per geomorphic reach (excepting geomorphic reaches associated with
Devils Canyon, i.e., MR-3 and MR-4).
• A replicate sampling strategy will be used for measuring habitat types within each
Focus Area, which will include a random selection process of mesohabitat types.
• Areas that are known (based on existing and contemporary data) to be biologically
important for salmon spawning/rearing in mainstem and lateral habitats (i.e., critical
areas) will be sampled.
• Some areas for which little or no fish use has been documented or for which
information on fish use is lacking will also be sampled.
Based on these criteria, Focus Areas were selected within Geomorphic Reach MR-1 (one Focus
Area), Geomorphic Reach MR-2 (one Focus Area)2, Geomorphic Reach MR-5 (one Focus
Area), Geomorphic Reach MR-6 (four Focus Areas), Geomorphic Reach MR-7 (two Focus
Areas)3, and Geomorphic Reach MR-8 (one Focus Area) (R2 2013a, 2013b, 2013c). Focus
Areas were not selected for Geomorphic Reaches MR-3 or MR-4 due to safety considerations
related to Devils Canyon.
The Focus Areas were those deemed representative of the major features within each
geomorphic reach and included mainstem habitat types of known biological significance (i.e.,
where fish have been observed based on previous and/or contemporary studies), as well as some
locations (e.g., Slough 17) where previous sampling revealed few/no fish. Two of the Focus
Areas in Geomorphic Reach MR-6 (FA-144 [Slough 21], FA-138 [Gold Creek], one in
Geomorphic Reach MR-7 (FA-115 [Slough 6A]), and one in Geomorphic Reach MR-8 (FA-104
[Whiskers Slough]) contain specific habitat types that were found, during the 1980s studies, to be
consistently used by salmon for spawning and/or rearing. Overall, 92 percent of the sockeye, 70
percent of the chum, and 44 percent of the slough-spawning pink salmon were found in just these
four sloughs. The Focus Area in Geomorphic Reach MR-7 included Slough 6A which, based on
the 1980s studies, provided primary juvenile rearing habitat; the Focus Area likewise included
side channel and upland slough habitats that had been modeled in the earlier studies. By
definition, these areas of known fish use represent “critical areas” and were included in the Focus
Areas to allow some comparisons with the 1980s data. The upper two Focus Areas (one in
Geomorphic Reach MR-1 and one in Geomorphic Reach MR-2) were selected based on their
representativeness of the respective geomorphic reaches and the inclusion of a mix of side
channel and slough habitat types. However, these areas were not sampled for fish in the 1980s.
The Focus Areas range in length from 0.5 mile to 1.8 miles (Table 4.2-3). Details of each of the
Focus Areas, including their identification number, common name, description, geomorphic
reach assignment, location (PRM), length, habitat types included in the Focus Area, fish use and
types of instream flow studies conducted in the 1980s, and the rationale for selection, are
2 MR-2 originally contained two Focus Areas – FA-171 (Stephan Lake, Simple Channel) and FA-173 (Stephan Lake
Complex). Based on consultation with the TWG (see R2 2013c), FA-171 (Stephan Lake, Simple Channel) was
deleted from MR-2.
3 MR-7 originally contained one Focus Area – FA-115 (Slough 6a). Based on consultation with the TWG (see R2
2013c), a new Focus Area was established in MR-7 (FA-113[Oxbow 1]).
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presented in Table 4.2-3; maps of each of the areas are depicted in Figure 4.2-1 through Figure
4.2-10.
The Focus Areas were assumed to have included side channels, side sloughs, upland sloughs,
and tributary mouths that were representative of these habitat types in other portions of the river.
This assumption has been initially evaluated using the results of the aerial imagery-based habitat
mapping. The results of that analysis were presented in a Draft Middle and Lower River Focus
Areas TM filed with FERC on January 31, 2013, and was subsequently presented and discussed
during the TWG meeting on February 14, 2013. With consideration of the comments and
suggestions received from licensing participants, a Final Middle and Lower River Focus Areas
TM was filed with FERC on March 1, 2013 (R2 2013b). In accordance with the April 1 SPD, an
Instream Flow Technical Team meeting was held on April 26, 2013, and AEA conferred with the
TWG representatives concerning the changes to the Focus Area locations. On May 31, 2013,
AEA filed with FERC the Adjustments to Middle River Focus Areas TM, providing the details
requested in the April 1 SPD. Information in the Adjustments to the Middle River Focus Areas
TM provides supplemental information concerning the final selection of Focus Areas. These
results are summarized in ISR Study 8.5, Section 5.2. In addition, field surveys were initiated in
2013 to ground-truth the aerial imagery-based habitat mapping results (see ISR Study 9.9).
Detailed surveys were initiated on the lower seven of the ten Focus Areas in 2013; limited
surveys were completed on the upper three Focus Areas (FA-151 [Portage Creek]; FA-173
[Stephan Lake Complex]; FA-184 [Watana Dam]) due to access restrictions associated with
Cook Inlet Regional Working Group (CIRWG) lands.
The data and information collected in 2013 from this study and other related investigations will
be reviewed, and necessary refinements to existing selected study sites will be determined in
2014.
Middle River Segment Sites Outside of the Focus Areas
In addition to the identified Focus Areas, a total of 83 cross-sectional transects were established
in 2012 and 2013 in the Middle River Segment and flow data collected to support development
of the Open-water Flow Routing Model (see ISR Study 8.5, Section 5.4). These transects were
primarily located across single thread sections of the river; however, some extend across more
complex sections, including portions of Focus Areas. In most cases, two to three sets of flow
measurements have been made at each transect. The resulting datasets of transects that traverse
fish habitat will be identified and reviewed for possible use in evaluating velocity-depth
distributions across the channel that can be related to biologically relevant criteria associated
with various life stage requirements (e.g., spawning, adult holding, juvenile rearing). In some
cases, it may be possible to develop actual habitat-flow relationships following a 1-D PHABSIM
type analysis. However, the need for doing so will be determined based on results obtained from
the Focus Area fish habitat-flow modeling. Once the main channel habitat mapping is completed
(ISR Study 9.9), each of the transect locations will be assigned to specific mesohabitat types
(e.g., riffle, run, glide, pool) that could be randomly selected for analysis. These additional
transects may also be useful for extrapolating results/relationships from measured to unmeasured
sites (see ISR Study 8.5, Section 4.7). Supplemental main channel transects may be established
during the next year of study as needed to more fully characterize main channel habitats, either
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as part of the Focus Area analysis or at separate locations associated with specific mesohabitat
types. The need for and number of supplemental transects will be determined based on results of
the habitat mapping.
4.2.1.3. Lower River Study Area/Study Site Selection
The determination of whether, and the extent to which, studies would be extended into the Lower
River Segment was presented in a March 1, 2013 TM (R2 2013b) and was based upon
consideration of six criteria. Those criteria are listed below along with relevant information and
data that formed the basis for extending studies into the Lower River Segment (portions of
March 1, 2013 TM reproduced below).
• Criteria 1 - Magnitude of daily stage change due to load-following operations relative
to the range of variability for a given location and time under existing conditions (i.e.,
unregulated flows)
o Results of the Open-water Flow Routing Model were presented in R2 et al.
(2013) and discussed during the February 14, 2013, TWG meeting. Results
indicated that pre- versus post-Project stage changes varied by location and
time and ranged at Gold Creek (Middle River Segment) from an increase in
daily average water level of up to 2 to 3 feet in the winter and a reduction of
daily average water level of as much as 5 feet in the summer during high
natural flow conditions (Figures 5.4-2 and 5.4-3 of R2 et al. 2013). More
typically the change would be about 3 feet in the summer. The predicted
change in stage in the upper portion of the Lower River Segment at Sunshine
ranged from an increase in daily average water level of up to 1 to 2 feet in the
winter and a reduction in water level of as much as 3 feet in the summer
during high flow conditions (Figures 5.4-4 and 5.4-5 of R2 et al. 2013). Daily
and hourly changes in stage during the summer period at Sunshine were
predicted to range from 0.6 to 0.8 feet, but accurate estimates for the winter
period are contingent on completion of the winter flow routing model.
• Criteria 2 - Magnitude of monthly and seasonal stage change under Project operations
relative to the range of variability under unregulated flow conditions
o Results of a comparative hydrologic analysis considering existing and with-
Project operations was completed by Tetra Tech and presented and discussed
during the February 14, 2013, TWG meeting (Tetra Tech 2013a). These
results were based on a 61-year extended discharge record that had been
developed by the USGS. Comparisons were made of monthly flows and
annual flows under pre-Project and a maximum load-following scenario.
Results showed substantial changes in seasonal flows during both the summer
(Project operational flows were lower) and winter (Project operational flows
were higher) periods (as had been noted in the Pre-Application Document)
with summer changes most pronounced in the upper portions of the river (pre-
Project/post-Project flows at Gold Creek in July: 20,000 cubic feet per second
(cfs) versus 6,980 cfs; and at Susitna Station 122,000 cfs versus 108,000 cfs)
while winter changes were evident throughout the entire river length (pre-
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Project/post-Project flows at Gold Creek in January: 1,280 cfs versus 8,840
cfs; and at Susitna Station – 7,910 cfs versus 15,500 cfs). Results of flow-
duration analysis demonstrated the shifts in flow magnitudes that would occur
with Project operations.
o Flood frequency analysis likewise indicated there would be changes in return
periods of specific flood magnitudes. For example, at Gold Creek, a two-year
flood event (i.e., a flood that occurs on average once every two years) of
43,700 cfs would, under maximum load-following operations, occur once
every 12 years. Likewise, at Susitna Station, a two-year flood of 170,300 cfs
would occur once every five years.
o Further hydrologic analysis will be completed as part of an Indicators of
Hydrologic Alteration (IHA) analysis described in ISR Study 8.5, Section 4.3.
• Criteria 3 - Changes in surface area (as estimated from relationships derived from
LiDAR and comparative evaluations of habitat unit area depicted in aerial digital
imagery under different flow conditions) due to Project operations
o Because the analysis of LiDAR data is still ongoing, inferences of surface
areas were drawn from the previous work of R&M Consultants and Trihey
and Associates (1985). Review of that document and the analysis presented
indicated that changes in surface area with flows can be pronounced
depending upon the range of flows considered, as well as on specific habitat
types (e.g., side channel, side sloughs). As R&M Consultants and Trihey and
Associates (1985) noted, surface area responses are a function of streamflow
and channel geometry. Examples of flow responses to wetted surface areas
for different locations in the Lower River Segment are found in Figures 3-1
through 3-4 of R&M Consultants and Trihey and Associates (1985).
Inspection of those relationships indicates that surface areas of certain types of
habitats can be quite sensitive to changes in main channel flows. Additional
analysis of these data was completed and is presented in Tetra Tech (2013b).
• Criteria 4 - Anticipated changes in flow and stage to Lower River off-channel habitats
o The flow and stage changes indicated by the results of the Open-water Flow
Routing Model and hydrologic analysis cannot be directly related to off-
channel habitats since results of the LiDAR analysis have not been completed
and detailed bed topography of specific areas have not yet been acquired.
However, reasonable inferences were made based on the timing, magnitude,
and duration of flow and stage changes associated with the proposed Project
operations on different types of lateral habitats. For example, it is reasonable
to assume that some of the lateral habitats inundated under pre-Project flow
conditions could become partially dewatered or disconnected from the main
channel under summertime project operations due to reductions in flow and
stage. Conversely, under wintertime operations, habitats that may normally
be disconnected from the main channel and operate as clear water side slough
habitats may become connected due to flow increases and breaching at the
head end of the channel resulting in turbid water conditions.
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• Criteria 5 - Anticipated Project effects resulting from changes in flow, stage, and
surface area on habitat use and function, and fish distribution (based on historical and
current information concerning fish distribution and use) by geomorphic reaches in
the Lower River Segment
o Based on the anticipated changes in stage and flows in the Lower River
Segment, it was reasoned that there would likely be some effects on fish
habitat and fish distribution resulting from Project operations.
• Criteria 6 - Initial assessment of potential changes in channel morphology of the
Lower River based on Project-related changes to hydrology and sediment supply in
the Lower River
o The initial assessment of potential channel changes was performed and
reported in three technical memoranda developed in the 2012 Geomorphology
Study: Stream Flow Assessment (Tetra Tech 2013a), Development of
Sediment-transport Relationships and an Initial Sediment Balance for the
Middle and Lower Susitna River Segments (Tetra Tech 2013c), and
Reconnaissance Level Assessment of Potential Channel Change in the Lower
Susitna River Segment (Tetra Tech 2013d).Collectively, the conclusions from
each analysis indicated that Project operations associated with changes in
hydrology would likely influence the sediment balance in the Lower River
Segment leading to changes in channel morphology and associated fish
habitats.
Mainstem Habitat types in the Lower River Segment include main channel, side channels and
sloughs, backwater, and tributary mouths (Tetra Tech 2013b). In comparison to the Middle
River, the Lower River channel exhibits much lower gradient with a wider floodplain containing
numerous subchannels. As noted above, a Focus Area study approach has been employed for the
Middle River segment to describe existing conditions and the response of habitats to proposed
Project releases. Modeling of the Middle River Focus Areas will integrate studies of fisheries,
geomorphology, groundwater, riparian, ice processes, and water quality. Hydraulic conditions
within these Middle River Segment Focus Areas will be based on 2-D modeling that will be
integrated into a PHABSIM-type analysis of potential fish habitat. However, the size and
complexity of the Lower River Segment renders a 2-D modeling approach of specific areas
infeasible. Rather, study sites in the Lower River Segment were selected in Geomorphic
Reaches LR-1 and LR-2 based on a combination of representative and critical study sites.
Instream flow sites were limited to these upper two geomorphic reaches in the Lower River
Segment since Project effects become more attenuated downstream (based on results of the
Open-water Flow Routing Model). Study areas were initially identified by AEA’s
interdisciplinary team of representatives from geomorphology, instream flow-fish, instream
flow-riparian, and groundwater. One area was selected in each of the upper two geomorphic
reaches 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 95.4 was selected as representative of the habitat types in
LR-1 (Figure 4.2-11), and the area around Caswell Creek near PRM 67.3 was selected as
representative of habitat types in LR-2 (Figure 4.2-12).
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Fish habitats in the Lower River Segment will be modeled using a 1-D approach involving
transects selected to represent major habitat types within each geomorphic reach. Data collection
and modeling efforts were conducted in LR-1 in 2013 (see ISR Study 8.5, Section 4.6) and will
be completed in LR-2 during the next year of study.
In addition to describing representative habitat types in LR-1 and LR-2, tributary mouths were
identified as potential critical sites. During the 1980s, the primary salmon spawning areas within
the Lower River Segment appeared to be clearwater tributaries (R&M Consultants, Inc. and
Trihey & Associates 1985), although 1980s sampling limitations may have overlooked some
mainstem salmon spawning. Low velocity backwater areas near tributary mouths were used as
holding areas by adult salmon during upstream migration into the tributaries, and tributary
mouths became a major component of Lower River studies during the 1980s. In addition to
evaluating potential effects of Project flow releases on adult salmon holding areas at Lower
River Segment tributary mouths, 1980s studies included analyses of salmon access into
tributaries and the geomorphic stability of tributary mouths. Thirteen Lower River Segment
tributary mouths were selected for study in the 1980s (Table 4.2-4) (R&M Consultants, Inc. and
Trihey & Associates 1985).
Results from 2012 and 2013 biological studies support the continued importance of Lower River
Segment tributary mouths as salmonid habitat. During 2012, habitats in LR-1 and LR-2 were
opportunistically surveyed to collect HSC. Of the 69 HSC observations of adult, juvenile, and
fry life stages, 42 percent were located in tributary mouth macrohabitats. Of the 13 tributary
mouths studied in the 1980s, five were selected for study during 2013. Trapper Creek and Birch
Creek are located in the vicinity of the LR-1 study area, and Sheep Creek and Caswell Creek are
located in the vicinity of the LR-2 study area. The Deshka River was identified as an important
adult salmon holding area during the February 14, 2013, TWG meeting, and the Deshka River
mouth was added to the list of 2013 study areas. The mouth of the Kashwitna River is located
near the LR-2 study area, but it was not selected for study in 2013 because it does not appear to
be heavily influenced by potential Project flow releases (Table 4.2-4). Studies were completed
in Trapper and Birch creeks in 2013; Sheep Creek, Caswell Creek, and Deshka River will be
sampled during the next year of study.
4.2.2. Variances from Study Plan
AEA implemented the methods as described in the Study Plan with the exception of the variance
explained below. While land access was not available for the three upper Focus Areas adjacent
to Cook Inlet Regional Working Group (CIRWG) lands in 2013, this was not considered a
variance because this study was designed to collect data over multiple years.
Sampling of LR-2 was originally scheduled for 2013 but not completed and is now scheduled for
the next year of study (see ISR Study 8.5, Section 4.6.2). However, this variance will not have a
substantive effect on the completion of this study since all field work, data analysis and modeling
will be completed prior to submittal of the license application.
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4.3. Hydrologic Data Analysis 4
AEA implemented the methods as described in the Study Plan with the exception of the
variances explained below (ISR Study 8.5, Section 4.3.2).
AEA’s hydrology program includes; 1) an assessment of existing hydrology data that will
summarize seasonal and long-term hydrologic characteristics for the river including daily,
monthly, and annual summaries, exceedance summaries, and recurrence intervals of small and
large floods; and 2) the installation and monitoring of a number of mainstem and tributary gages
that will fill-in data gaps, contemporize the flow record, and provide for a more robust
hydrologic data set. Activities completed in 2013 are summarized below; more detailed
information regarding data collection and analytical techniques is provided in ISR Study 8.5,
Appendix A.
4.3.1. Methodology
4.3.1.1. Hydrologic Data Collection
In 2013, AEA continued the collection and analysis of hydrologic data at a number of existing
mainstem gaging stations, collected winter flow measurements at selected USGS gages, and
installed and monitored gages at ten tributary gages.
The mainstem Susitna River hydrologic data collection included stage and discharge
measurements, cross-sectional and areal bathymetric surveys, velocity mapping, and roughness
determinations.
Surveying was completed using several methods depending on survey objectives. This included
Global Positioning System (GPS) surveying that applied both high accuracy methods and the use
of hand-held GPS systems for reconnaissance surveying, as well as, in some locations, optical
level surveying to determine water level elevations and to set up temporary benchmarks at
hydrology stations. In all cases where accuracy was important, the surveying of points and
locations was completed using Real Time Kinematic (RTK) GPS with reference to the geodetic
control network (ISR Study 8.5, Appendix A). RTK surveying is the method by which a single
reference station is used to provide real-time carrier phase corrections by radio link to one or
more roving GPS receivers, providing up to centimeter-level accuracy under ideal conditions. In
this study, RTK surveys used two or more GPS units. Data points such as temporary benchmark
elevations, which require a level of accuracy greater than RTK methods can provide, were tied
using static GPS observations. Instantaneous stage measurements were performed using either
RTK GPS methods or optical levels, using benchmarks and geodetic control points that are part
of the control network. All AEA gaging or water level stations had RTK or control point surveys
established as well as temporary benchmarks installed to allow efficient optical-level loop
surveys. Surveys to check the accuracy of existing Light Detection and Ranging (LiDAR)
information needed for defining floodplain and dry channel topography were made at 25
locations in the Lower Susitna River Segment and 125 locations in the Middle and Upper Susitna
4 Note – this section followed the Open-water Flow Routing Model and Reservoir Operations Model section in the
RSP. It was moved ahead of that section in this ISR to reflect proper sequencing of data collection and analysis.
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River Segments. Over 19,000 ground survey shots were collected in 2013 that can be used to
spot-check the LiDAR DEM for accuracy. Additional information concerning the LiDAR
validation is found in Geomorphology ISR Study 6.6.
During open-water conditions, mainstem discharge measurements were performed using ADCPs
following current USGS guidance (Mueller and Wagner 2009). Relying on the Doppler
principle, ADCPs measure water velocity using acoustic reflections from suspended particles
(ISR Study 8.5, Appendix A). The cross-sectional bathymetric surveys were performed as part
of discharge measurements completed using the Sontek M9 ADCP. The Sontek M9 is equipped
with a 0.5-megahertz (MHz) vertical-beam depth sounder and RTK GPS positioning. Together
with shore-based RTK GPS surveys, the digital elevation model is used to develop cross-sections
for use in the Open-water Flow Routing Model.
Stage, discharge and bathymetric surveys were collected at various cross-sections and within
Focus Areas (including inlets and outlets) using the surveying and ADCP methods. The cross-
sections were either surveyed using ADCPs or single-beam depth sounders. In either case,
bathymetric data were referenced to the Project geodetic control network using RTK GPS survey
methods. A description of the Focus Area measurements is also provided in Geomorphology ISR
Study 6.6.
Continuous stage measurements (along with temperature and meteorological data) were recorded
at AEA hydrology stations at 15-minute intervals and made available to studies via the real-time
reporting data network (ISR Study 8.5, Section 4.4). Continuous stage measurements were made
using vented pressure transducers accurate to within about 0.02 feet. The hydrology stations
required periodic water elevation surveys, either performed by RTK surveying or by optical-
level loop survey methods. Table 4.3-1 shows a listing of the stations in the real-time reporting
data network. Pressure transducers and water temperature sensors were added at hydrology
stations to provide the Groundwater (Study 7.5) and Ice Processes (Study 7.6) study teams with
winter pressure (water pressures under ice, water levels in ice-free or partial ice-covered reaches)
and water temperature measurements. Sensors lost during spring break-up were replaced as soon
as it was safe and practical to install. All data were recorded on Campbell Scientific CR1000
data loggers, with internal memory backup.
Winter streamflow measurements provide valuable information for understanding hydraulic
conditions in the mainstem Susitna River during seasons when groundwater plays a more
prominent role in aquatic habitat functions. Periodic winter discharge measurements (January
and March) were completed (using a combination of ADCP and current meter methods) at
selected hydrology stations in winter 2013. These measurements were made in coordination
with USGS winter measurement programs to allow collection of synoptic data sets. The 2013
winter discharge measurement occurred at the AEA hydrology stations ESS70 (PRM 187.1),
ESS65 (PRM 176.5), ESS60 (PRM 168.1), ESS50 (PRM 124.1), ESS45 (PRM 116.6), and
ESS40 (PRM 107.2) (Table 4.3-2). The methods and results of winter measurements can be
found in the Ice Processes ISR Study (7.6). The mainstem discharge measurements will help
assess gaining and losing river reaches during winter conditions.
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4.3.1.1.1. Tributaries to the Susitna River
Twelve tributary gaging stations were installed at selected tributaries in 2013 to provide
additional data for hydrologic and fisheries studies (Table 4.3-3; Figure 4.3-1). Ten of the
twelve stations have continuous recording pressure transducers and two had spot discharge
measurements collected. The gaging stations were installed in spring/early summer of 2013 to
help measure the spring snowmelt peaks. Three of the tributaries had a companion stage-only
site located in the downstream slough of the mainstem of the Susitna River. The stations report
data similar to the existing mainstem AEA gages. Details concerning the installation,
monitoring, and data analysis procedures of the tributary gages are presented in ISR Study 8.5,
Appendix A.
4.3.1.1.2. Hydrologic Data Real-time Reporting Network Operations
The data network system and stations that were installed in 2012 were operated throughout 2013
as a means to provide real time updates on hydrology and other meteorological parameters at
locations throughout the river (Table 4.3-1 and Table 4.3-2). These stations are connected
through a radio telemetry system using spread-spectrum radio communication and a network of
repeater stations to communicate to a central base station.
The network system includes a naming convention that serves to identify station locations and
the primary purpose of the station. The convention is of the form: EX1X2X3 where E represents
AEA, X1 indicates the river drainage (S = Susitna, C = Chulitna, T = Talkeetna), X2 is the
primary station purpose (B = base station; C = camera station; F = Pit tag array; G = groundwater
station; M = meteorological station; R = repeater station; and S = surface water station), and X3 =
station sequence number, or specific Focus Area number and PRM (e.g., FA-104). For example,
station ESS80 represents Alaska Energy Authority station on the Susitna River for Surface water
and is station 80. More details concerning the network system are described in ISR Study 7.5.
4.3.1.2. Hydrologic Data Analyses
The primary activities associated with hydrologic data analysis completed in 2013 included data
compilation and QA/QC reviews of flow and stage data collected from the AEA mainstem and
tributary gage stations, compilation and review of winter gaging data, correction of pressure
transducer records and conversions to station gage height records, rating curve development,
stream flow computations, and cross-section and bathymetric data post-processing. Data
analysis is ongoing and will include the development of daily and hourly inflow routing to Focus
Areas from the Susitna River Open-water Flow Routing Modeling and analysis for selected
tributaries. Analysis will also include calculations of hydrologic data statistics for the Susitna
River and selected tributaries.
Efforts in 2012 already established the 61-year period extending from Water Years 1950 through
2010 (October 1, 1949 to September 30, 2010) as the hydrologic period of record for the Project.
This record was based on a series of USGS gages in the Susitna River Basin that were measured
over different time periods (Table 4.3-4 and Table 4.3-5). The periods of record of measured
flows at each of the sites listed in Table 4.3-4 and Table 4.3-5 were extended to cover the 61-
year period (Water Years 1950 through 2011) by synthesizing the missing daily flow records to
fill in the gaps (Curran 2012).
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Work was also completed in 2013 on selecting representative years to reflect wet, average and
dry conditions and warm and cool Pacific Decadal Oscillations. The selection of representative
year types is needed so that a range of climatic and hydrologic conditions can be considered
when evaluating Project alternatives. An update on the process AEA is applying in the selection
of representative years was provided during the November 13-15, 2013 IFS-TT Riverine
Modelers Meeting and also at the Q4 2013 TWG Meeting.
4.3.1.3. Indicators of Hydrologic Alteration and Environmental Flow Components
The assessment of hydrologic data will include the calculation of summary statistics that will be
useful for describing the seasonal and short-term and long-term hydrologic characteristics of the
Susitna River. This will include daily, monthly, and annual summaries, and exceedance
summaries and recurrence intervals of small and large floods. This analysis was initiated in 2012
and continued in 2013 as more data were added to the hydrologic record. In addition to the
computation of summary statistics, AEA will utilize the Indicators of Hydrologic Alteration
(IHA) and Range of Variability models developed by The Nature Conservancy (TNC 2009) for
computing additional baseline hydrologic characteristics. The IHA models are components of an
analytical software package designed to assess the impacts of a project on unregulated
hydrologic conditions (TNC 2009).
In 2013, AEA applied the IHA models to the hydrology of the Stikine and Taku rivers as part of
the Biological Cues Analysis described in ISR Study 8.5, Section 4.5, and presented in Appendix
B. AEA will develop and finalize the IHA approach that will be used for the Susitna River with
input from the TWG.
4.3.2. Variances from Study Plan
AEA implemented the methods as described in this section of the Study Plan with the exception
of the variances explained below.
4.3.2.1. Tributaries to the Susitna River
The RSP states that “Additional gaging stations will be added at selected tributaries to help
provide additional hydrologic analysis for hydrologic and fisheries studies. These tributaries will
include Fog Creek, Portage Creek, and Indian River. These gaging stations will be installed in
spring 2013 to help measure the spring snowmelt peaks.”
Ten continuous gage sites and two spot measurement sites were established on tributaries of the
Susitna River in 2013. Indian River was one of these gage sites, but Fog Creek and Portage
Creek were not gaged due to land access issues. Gaging of Fog Creek and Portage Creek is
proposed in the second year of study (ISR Study 8.5, Section 7.4). Tributary inputs in the Open-
water Flow Routing Model will be estimated based on drainage area and then adjusted using
available tributary gaging data. Data gaps associated with the lack of gage sites on Fog Creek
and Portage Creek in 2013 will not significantly affect accretion calculations used in the Open-
water Flow Routing Model.
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4.3.2.2. Representative Years
The RSP states that “Five representative years will be selected that represent, wet, average, and
dry conditions, and warm and cool Pacific Decadal Oscillation phases so that Project effects for
various project alternatives can be evaluated under a range of climatic and hydrologic conditions.
In addition, a multi-year continuous flow record will be evaluated to identify year-to-year
variations independent of average, wet, or dry conditions. The specific representative years and
the duration of the continuous flow record will be selected by AEA in consultation with the
TWG in Q3 2013.”
A variance has occurred in the schedule of the selection of representative years. The selection of
representative years will address multiple resource interests including geomorphology and ice
processes. The topic of representative years was discussed at both the November 13-15, 2013
IFS-TT Riverine Modelers Meeting, and at the Q4 2013 TWG meeting. A technical meeting is
also scheduled for 2014. Finalization of the selection of representative years will not be needed
until IFS-related modeling begins. The schedule identified in the Study Plan was an effort to
stagger development of supporting information; however, delaying selection of representative
years until 2014 will not affect the ability to meet study objectives. An initial proposal and
rationale for the selection of representative years is included in ISR Study 8.5, Section 5.3.
4.3.2.3. Indicators of Hydrologic Alteration and Environmental Flow Components
The RSP states that “In consultation with the TWG, the IHA/EFC or HEC-EFM programs will
be used to evaluate existing conditions and alternative operational scenarios for the Susitna-
Watana Project. Select hydrologic parameters, considered to be ecologically relevant to Susitna
River resources, will be developed in consultation with the TWG in Q3 2013, and initial results
and potential modification reviewed by the TWG in Q1 2014.” The RSP also states that “Interim
results of the IHA-type analyses will be presented in the ISR.”
A variance in schedule has occurred for the IHA analysis. The determination of the appropriate
methodology to apply, and parameters to use, from the Indicators of Hydrologic Alteration has
continued through Q4 of 2013. The study objectives will be achieved as the development of the
IHA analysis is ongoing in conjunction with the determination of representative years. A
description of an initial proposed methodology is provided in ISR Study 8.5, Section 5.4. This
methodology will undergo continued discussion and coordination with the TWG. It is
anticipated that a fully developed and implementable methodology will be available for use prior
to the USR.
4.4. Reservoir Operations Model and Open-water Flow Routing
Model
AEA implemented the methods as described in the Study Plan (RSP Section 8.5.4.3) with the
exception of the variances explained below (ISR Study 8.5, Section 4.4.2).
Project operations will cause hourly, daily, and seasonal changes in the Susitna River flows
downstream of the proposed dam as compared to existing conditions. Seasonally, Project
operations will likely include storing water during the snowmelt season (May through August)
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and releasing it during the winter (October through April) (AEA 2011). This would reduce flows
downstream of the proposed dam site from May through August and increase flows October
through April. To evaluate those changes, two models were developed in 2013 to simulate
existing and Project conditions; a Reservoir Operations Model to simulate the storage and release
of water within the Project reservoir, and an Open-water Flow Routing Model to simulate the
movement of releases from the proposed dam to downstream locations. These models and their
development are described in the sections below.
4.4.1. Methodology
4.4.1.1. Reservoir Operations Model
The HEC reservoir system simulation model, HEC-ResSim (USACE 2007) Version 3.0, was
adapted and utilized for the Project in 2012 and 2013 to forecast a range of reservoir outflows
associated with different operational scenarios that will ultimately be evaluated as part of the
IFS. The HEC-ResSim is a general-purpose, sequential stream flow routing model that is free
and in the public domain. The HEC-ResSim model has an hourly time increment of operation.
HEC-ResSim includes a graphical user interface, and graphics and reporting facilities. The HEC
Data Storage System (HEC-DSS) is used for storage and retrieval of input and output time-series
data.
HEC-ResSim incorporates a reservoir water balance that is governed by a set of operating rules
such that inflow minus all outflows, including turbines, valves, and spillway, equals the change
in reservoir storage for a given time period. Required input data to the model includes long-term
reservoir inflow time-series data. For the proposed Watana Dam, the reservoir inflow was
provided from the continuous 61-year record of daily flows for Water Years 1950 through 2010.
The USGS provided the basis for the continuous long-term daily flows with a Susitna River
watershed record extension study (Curran 2012) that includes both recorded and correlated
flows. Two of the USGS gages included in the study were Susitna River at Gold Creek (Gage
No. 15292000), which has a drainage area of 6,160 square miles, and Susitna River near
Cantwell (Gage No. 15291500), which has a drainage area of 4,140 square miles. The proposed
Watana Dam has a drainage area of 5,180 square miles, about halfway between these two USGS
gages. Inflows to Watana Reservoir were based on proportioning the USGS flows based on
drainage area.
As was also the case in the 1980s studies, providing environmental flows at the Gold Creek
USGS gage will presumably be one of the a primary reservoir operating criterion. With the
proposed Watana Dam, a majority of the flow tributary to the Gold Creek USGS gage will be
regulated, but significant natural inflows between Watana Dam and Gold Creek must also be
included. To provide the local inflows below the proposed dam, a 61-year daily record was
constructed from the Gold Creek USGS gage flows minus the calculated Watana Reservoir
inflows. This provided a time-series of natural local inflow data that can be used as input to the
model.
The HEC-ResSim model will provide results for many parameters such as the simulated
reservoir elevation and powerhouse generation. Data can be plotted or output provided in
standard or user-customized reports. One of the key parameters, total reservoir outflow, will
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serve as the primary input to the HEC-RAS model that will be used in the IFS analysis. Total
reservoir outflow is the summation of all outlets, including the powerhouse, spillway, and fixed-
cone outlets. The extent of data analysis will be determined based on needs of other resource
models, the number and types of representative years identified for analysis (e.g., wet, dry, and
average years), potentially for both the warm and cool phases of the Pacific Decadal Oscillation
(PDO) (ISR Study 8.5, Section 4.4), as well as the number of operational scenarios specified by
AEA.
In addition to HEC-ResSim, AEA also applied a reservoir operation model developed by MWH
for making some preliminary operational runs. The MWH model can perform an automated
iteration to maximize firm energy to specified reliability criteria, which then form the input
generation requirements for the HEC-ResSim model. Execution times in the MWH reservoir
operation model are several times faster than for HEC-ResSim, and the MWH model can be
programmed to simulate unique or complex operation requirements.
4.4.1.2. Open-water Flow Routing Model
Steady-state flow models assume that velocity or flow at a given location remains constant.
Unsteady flow models are used when flows change rapidly and when the consideration of time is
an additional variable. One-dimensional unsteady flow hydraulic models are commonly used to
route flow and stage fluctuations through rivers and reservoirs. The HEC-RAS model (USACE
2010a, 2010b, and 2010c) was selected as the Open-water Flow Routing Model for routing stage
fluctuations downstream from the proposed Project dam under open-water conditions (i.e.,
summer, ice-free). Two different flow routing models have been developed: an open-water
model (HEC-RAS) described in this section of the ISR and a winter model to route flows under
ice-covered conditions described in ISR Study 7.6. The seasonal timing of the transition from
the HEC-RAS model to the ice processes model and vice versa will vary from year to year and
depends on seasonal climate conditions and conditions such as the onset of frazil and bank ice
formation in the fall and loss of river and bank ice following spring break-up.
Version 1 of the Open-water Flow Routing Model was developed in 2013 to analyze the impacts
of alternative Project operational scenarios that include load following, on changes in flow and
stage downstream of the proposed Watana Dam site. This model will utilize outputs from the
Reservoir Operations Model as input to assess the magnitude, timing and frequency of hourly
flow and stage conditions during open-water periods (i.e., ice-free) at numerous locations
longitudinally distributed throughout the length of the river extending from PRM 187.2
downstream to PRM 29.9 (about 1.5 miles downstream from the confluence with the Yentna
River) during open-water periods (i.e., ice-free).
The Open-water Flow Routing Model was developed using river cross-sections and streamflow
gaging stations established on the Susitna River. A total of three versions of the model will be
developed and provided for distribution with Version 1 developed and distributed in Q1 2013
and Version 2 in early 2014. Each successive version of the model will be refined and will
contain more detail based on additional information available. A comparison of the three
versions and the content contained in each is provided in Table 4.4-1.
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Cross-sectional data were collected in 2012 and 2013 in accordance with U.S. Geological Survey
(USGS) procedures and as described in ISR Study 8.5, Appendix C). This entailed surveying of
ground surface and water surface elevations at each cross-section using Real Time Kinematic
(RTK) GPS instrumentation. River bathymetry and flow velocities were measured using an
Acoustic Doppler Current Profiler (ADCP) system consisting of a Sontek M9 equipped with
RTK GPS positioning. Water surface slopes were also measured, photographs taken and
vegetation descriptions developed at each section. Flow measurements were made at each river
cross-section by completing at least four passes across the channel width.
A total of 88 cross-sections was surveyed in 2012 (16 between the proposed dam site and Devils
Canyon, 59 between Devils Canyon and the Three Rivers Confluence, and 13 downstream from
the Three Rivers Confluence) and an additional 80 cross-sections surveyed in 2013 between
PRM 29.9 and PRM 146. 1. The 2012 cross-sections were measured during three field trips
intended to capture high-flow (28,000 cfs), medium-flow (16,000 cfs), and low-flow (8,000 cfs)
conditions corresponding to the USGS gaging station at Gold Creek (Gage No. 15292000). The
2013 cross-sections were surveyed to improve the Open-water Flow Routing Model, to extend
the model down to PRM 29.9, to fill in data gaps from the 2012 cross-sections to capture high-,
medium-, and low-flow conditions, and to provide additional cross-sections needed in the
geomorphology model (Study 6.6) and for riparian analysis (Study 8.6).
The hourly flow records from USGS gaging stations on the Susitna River were also utilized to
help develop Version 1 of the Open-water Flow Routing Model. An additional 13 new mainstem
gaging stations (Table 4.3-2) were established on the Susitna River in 2012 and maintained in
2013 to measure stage every 15 minutes. Water temperature, air temperature, and time-laps
photographic (camera) images of river conditions were also collected at each station. Data
recorded at these stations will be used to calibrate flow pulse arrival time in the Open-water Flow
Routing Model, based on measured diurnal glacial melt pulses and rainstorm-generated flood
peaks. These stations also monitored water pressure under winter ice covered conditions.
During the development and calibration of Version 1 of the Open-water Flow Routing Model,
the drainage areas of ungaged tributaries were quantified and used to help estimate accretion
flows to the Susitna River between locations where flows are measured. The flow estimates
developed for ungaged tributaries will be refined based on flows that were measured in those
tributaries in 2013 (ISR Study 8.5, Section 4.4).
Because the results of the ice processes model are not yet available (Study 7.6), the downstream
extent of Project effects on flow and stage during the winter will be initially assessed by routing
winter-flow releases identified by the Reservoir Operations Model (ISR Study 8.5, Section 4.3)
downstream using the Open-water Flow Routing Model. Although stage and flow projections
during the winter will not be robust, they will provide sufficient information on downstream flow
and stage effects to support initial analyses.
Output from the Open-water Flow Routing Model provides the fundamental input data to
habitat-specific and riverine process-specific models described in ISR Study 8.5, Section 4.6;
ISR Study 8.6, and ISR Study 6.6.
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4.4.2. Variances from Study Plan
AEA implemented the methods as described in the Study Plan with the exception of the variance
explained below.
Section 8.5.4.3.1 of the RSP states that “The gaging stations initially installed in 2012 will be
maintained through 2013 and 2014 to help calibrate and validate the flow routing models and
provide data supporting other studies.” This section also states that one of the objectives is to
“Install and operate 13 water-level recording stations within the mainstem Susitna River.”
Version 1 of the Open-water Flow Routing Model (R2 et al. 2013) was developed in January
2013 following submittal of the RSP. During development of the Open-water Flow Routing
Model it became apparent that all 13 mainstem water-level recording stations were not needed
for calibration purposes (see Table 4.4-2 and Figure 4.4-1 for locations of these stations). Eight
of the original 13 sites were identified as high priority based in part upon their locations in the
river, the stability of the channel proximal to the stations, and accessibility; other sites were
considered low priority due to location or erosional changes in the channel profile during 2013.
As a result, some data gaps of water stage exist for the original 13 surface-water stations
locations. Three stations ((ESS80 (PRM 225), ESS30 (PRM 98.4), and ESS20 (PRM 29.9))
have complete or near complete data sets. Six stations ((ESS65 (PRM 176.5), ESS55 (PRM
152.2), ESS50 (PRM 124.1), ESS45 (PRM 116.6), ESS40 (PRM 107.2), and ESS35 (PRM
102.1)) have partial data sets. Stations ESS70 (PRM 187.1) and ESS60 (PRM 168.1) were not
operating during much of 2013. Stations ESS15 (PRM 24.7) and ESS10 (PRM 17.4) are
downstream of the lower extent of the Open-water Flow Routing Model and were installed to
provide basic hydrology data for supporting studies in the lower river. These data along with
available data from USGS at four additional sites along the mainstem of the Susitna River will be
used in calibration of Version 2 of the model. Given the availability of complete data sets at
seven locations (three ESS stations and four USGS stations), it is not anticipated that data gaps at
the other ESS stations will hinder achieving study objectives.
4.5. Habitat Suitability Criteria Development
AEA implemented the methods as described in the Study Plan with the exception of the
variances explained below (ISR Study 8.5, Section 4.5.2.
Habitat suitability criteria (HSC) curves and habitat suitability index (HSI) models have been
utilized by natural resources scientists for over two decades to assess the effects of habitat
changes on biota. HSC curves are designed for use in the Instream Flow Incremental
Methodology to quantify changes in habitat under various flow regimes (Bovee et al. 1998).
HSC curves describe the instream suitability of habitat variables (typically depth, velocity,
substrate and cover) related to stream hydraulics and channel structure. HSC curves can also be
developed for other variables influenced by flow including water quality (temperature, dissolved
oxygen, turbidity) and presence of groundwater upwelling/downwelling. HSI models were
originally designed for application with the Habitat Evaluation Procedures (HEP) (U.S. Fish and
Wildlife Service 1980) which could be applied to both terrestrial and aquatic habitats. However,
in the 1980s a series of HSI models were developed for a variety of fish species including most
salmonids to provide for a means to predict or evaluate the effects of anthropogenic factors on
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different fish species. These models describe how well each particular habitat variable meets the
habitat requirements of the target species and life stage, as described by a suite of environmental
variables (e.g., percentage fine sediments, water temperature, pH, dissolved oxygen, pool-riffle
ratio, and others (see Raleigh et al. 1986 for examples). Both HSC and HSI models are scaled to
produce an index between 0 (unsuitable habitat) and 1 (optimal habitat). Both models are
hypotheses of species-habitat relationships and are intended to provide indicators of habitat
change, not to directly quantify or predict the abundance of target organisms. In this ISR Study
8.5, HSC and HSI are considered together and are reported hereafter as HSC/HSI.
For the Susitna-Watana Hydroelectric Project aquatic habitat studies, data for developing both
HSC (i.e., depth, velocity, and substrate/cover) and HSI (e.g., turbidity, groundwater upwelling,
colonization rate, dewatering mortality) curves were collected in 2013. These data, in
combination with data collected in 2012 and data that will be collected during the next year of
study, will be used to develop final HSC/HSI curves that will be used with the hydraulic and
habitat models (ISR Study 8.5, Section 4.6) to estimate the effects of alternative operational
scenarios.
4.5.1. Methodology
Work completed by AEA in 2013 that was focused on development of HSC/HSI curves
included: 1) selection of target species and life stages; 2) development of draft HSC curves using
existing information; and 3) collection of site-specific HSC/HSI data from selected areas. This
information and these data will be used in combination with data collected during the next year
of study to develop both habitat utilization and preference curves for target fish species.
4.5.1.1. Select Target Species and Life Stages
Survey results from the 1980s technical studies were reviewed in 2013 and used to determine the
list of target fish species for potential development of HSC/HSI curves (Table 4.5-1). In
collaboration with the TWG (Q1 and Q2 2013 TWG meetings), a ranking of priority (high,
moderate, and low) fish species for which HSC/HSI curve development is targeted was
developed based on management status and/or potential sensitivity to potential Project operations
(Table 4.5-2). The highest priority species were generally considered the most sensitive to
habitat loss through manipulation of flows and are the highest management priority in the
Susitna River. The list of species and their priority ranking will continue to be evaluated
following review of the 2013 sampling results.
4.5.1.2. Development of Draft HSC/HSI Curves Using Existing Information
Although the first priority in development of HSC/HSI curves is through the use of site-specific
field data, a review and comparison of HSC/HSI curves developed as part of the 1980s
assessment and non-Susitna River literature-based HSC/HSI curves sets was completed in 2013.
This review relied heavily on information obtained as part of the 1980s assessments, in
particular, the Instream Flow Relationships Report (Trihey & Associates and Entrix 1985a,
1985b) and a four-volume series on the aquatic habitat and instream flow assessment (Hilliard et
al. 1985; Klinger-Kingsley et al. 1985; Steward et al. 1985; Aaserude et al. 1985). This
information was synthesized and compared with more contemporary curve sets developed for
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similar river systems (R2 2013e). In addition, the HSC/HSI data collected in 2012 was
compared with existing curve sets to see if patterns of microhabitat use were similar (R2 2013e).
A summary of the 1980s datasets available and reviewed to date is presented in Table 4.5-3. The
draft HSC/HSI curves reviewed as part of this effort are presented in the 2012 Compendium of
Technical Memoranda completed during Q1 2013 (R2 2013e).
4.5.1.3. HSC/HSI Study Area Selection
For the 2013 HSC/HSI sampling, a stratified random sampling approach based on macrohabitat
composition within each Focus Area (ISR Study 8.5, Section 4.2) and relative fish use, was used
for selecting sampling locations, with some adjustments made to final locations based on access
and safety considerations. This approach enabled representative sampling of the range of
macrohabitat types available to fishes within Focus Areas. In addition, HSC/HSI study sites
were also selected in four areas outside of the Focus Areas, two within geomorphic reach MR-6
and two in MR-7 (Figure 4.5-1). These areas were identified as areas of high fish use during the
1980s and 2012 surveys and were selected in consultation with the Fish Distribution and
Abundance (FDA) studies (ISR Study 9.6). All sample sites outside of the Focus Areas were
given a unique identifier, with the site name beginning with NFA (Non-Focus Area).
There are 10 Focus Areas located in the Middle River Segment of the Susitna River (Figure 3-1)
(see ISR Study 8.5, Section 4.2). The HSC/HSI sampling in Focus Areas in 2013 was limited to
seven Focus Areas including FA-104 (Whiskers Slough), FA-113 (Oxbow 1), FA-115 (Slough
6A), FA-128 (Slough 8A), FA-138 (Gold Creek), FA-141 (Indian River), and FA-144 (Slough
21). Due to access issues related to adjacent Cook Inlet Regional Working Group (CIRWG)
lands, no HSC/HSI sampling sites were located in FA-184 (Watana Dam), FA-173 (Stephan
Lake Complex), or FA-151 (Portage Creek). For the Focus Areas sampled, macrohabitats were
first split into defined linear habitat units. For main and side channel macrohabitats, these units
were defined as 500-meter-long (1,640 feet) thalweg segments. Off-channel macrohabitat units
were similarly split into 200-meter-long (656 feet) segments. These units were then stratified
into areas of known fish use versus unknown fish use based on studies conducted in the 1980s
and in 2012 (R2 2013e). If this stratification resulted in multiple segments within a stratum or
grouping, random segments were selected for sampling. The number and distribution of selected
habitat units within each Focus Area are displayed in Table 4.5-4.
For main channel habitats, a single 100-meter (328 feet) sampling site was selected from within
each of the randomly selected habitat units (i.e., 500-meter [1,640 feet] main channel units). The
sample site was placed within the habitat unit, in an area that visually appeared to have the
greatest diversity of microhabitat types (i.e., fast and slow, deep and shallow water) and could be
safely worked. The width of the sampling site was determined in the field based on the sampling
method employed and on safety concerns. In all other habitat types (side channels, sloughs,
tributary mouths, backwaters, and plumes), a 50-meter (164 feet) sampling site was placed
within each randomly selected habitat unit using the same considerations discussed above for the
main channel. The general location of each sampling site within the Middle River Segment is
presented in Figure 4.5-1.
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4.5.1.4. Collect Site-Specific Habitat Suitability Information
Collection of HSC/HSI data was initiated in the Susitna River during a pilot effort in 2012. The
primary goals of the 2012 pilot effort were to evaluate various sampling techniques, assess
logistical aspects of site access, and begin collection of site-specific habitat suitability data for
target species (R2 2013e). Information gathered during the 2012 sampling effort was used to
help guide development of the 2013 field studies. The 2013 effort included the collection of
both fish microhabitat utilization and availability data. The collection of habitat availability data
along with habitat utilization data will allow the development of both habitat preference curves,
as well as habitat utilization curves.
For 2013, a total of 68 HSC/HSI data collection sites were randomly selected (includes both 50-
and 100-meter sampling sites [164 and 328 feet, respectively]) for collection of field data to
define microhabitat use by spawning and freshwater ‘rearing’ (juvenile resident or anadromous
fish) or ‘holding’ (adult resident fish) life stages of target fish species. As previously stated,
specific sampling sites were located based on professional judgment within randomly selected
macrohabitat units to capture the greatest diversity of microhabitat (slow and fast, deep and
shallow water) and in areas with known concentrations of high fish use. In general, the same
sample sites were visited two to three times during the summer (June-September) to detect any
temporal changes in habitat use. Fish-use observation methods included pedestrian and
underwater (snorkel) fish observations, single-pass backpack electrofishing, pole/beach seining,
and backpack electrofishing with a mobile downstream blocking seine. Observation methods
varied depending on environmental conditions, and were subject to ADF&G Fishery Resource
Collection Permit requirements.
During each survey, microhabitat data (water depth, velocity, substrate composition and
embeddedness, and cover) were recorded at each fish observation point. While fish microhabitat
use information was collected on all species and life stages encountered (with the exception of
sculpin), the locations, timing, and methods of sampling efforts targeted key (high-moderate
priority) species and life stages identified in consultation with the TWG during Q1 2013. A
more detailed description of each of the methods used during 2013 field sampling is presented
below.
Prior to conducting any fish surveys within a sample site, turbidity samples were taken at the
upstream and downstream ends of each sample site. Additional samples were taken if there were
visible differences (e.g., clear water plumes, upwelling) in turbidity level between the upstream
and downstream extent of the sampling site.
Additionally, vertical hydraulic gradient measurements were recorded at a minimum of three
locations (downstream most, center, and upstream most end) within the length of each sampling
site following procedures described by the USGS 2000 Fact Sheet. Additional measurements
were collected near clusters of spawning redds/nest if large differences were noted between any
of the three measurements within the sampling site. The vertical hydraulic gradient device was
tested early during the survey period and found to be effective in detecting positive (upwelling)
and negative (downwelling) hydraulic gradients. Although visual and temperature indications of
groundwater upwelling were also noted, the vertical hydraulic gradient device was used
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extensively for detecting the presence of groundwater upwelling or downwelling within
sampling sites, which will be important in developing HSC/HSI curves.
4.5.1.5. Spawning/Redd Surveys
The timing and location of spawning/redd surveys were based in part on fish distribution and
periodicity data obtained from the 1980s studies and 2012 surveys of the Susitna River. This
information was helpful in identifying sample timing and areas with the highest concentrations
of spawning activity.
Because redds can often be inconspicuous and superimposed over one another, spawning site
observations were made by experienced fish biologists. When actively spawning or guarding
adults were located, HSC/HSI spawning surveys were conducted using snorkeling and
pedestrian-based observations. The presence of at least one actively spawning or guarding fish
of known species was required to qualify as an individual fish-use spawning site or redd. If a
redd was located without a fish either spawning on or guarding a specific channel location, it was
not used as an HSC/HSI fish spawning site. If a site was designated a spawning HSC/HSI site
then one snorkeler or pedestrian surveyor entered the downstream end of the sampling site,
stopping at each individual redd to first record the salmon species associated with the redd and
then record the following information:
• Redd location (Lat/Long GPS coordinates) and distance from downstream end of sample
site and distance from water’s edge (nearest foot)
• Water depth at upstream end of the redd (nearest 0.1 foot), using a top setting rod
• Mean water column velocity at upstream end of redd (feet per second to nearest 0.05 fps),
using a Price AA current meter
• Substrate size (dominant, sub-dominant, percent composition and embeddedness within
the redd) characterized in accordance with a Wentworth grain size scale modified to
reflect English units (Table 4.5-5)
• Water temperature (to nearest 0.1°C), dissolved oxygen (ppm), and conductivity (µS)
measurements were made at the lower, middle, and upper ends of each sampling site and
at a subset of the individual redds and/or clusters of redds
• In addition, if the redd was located proximate to habitat structure or cover features, then
the cover type was noted: boulder, wood debris, aquatic vegetation, undercut bank, and
overhanging vegetation)
The accuracy of water velocity meters and water quality probes was assessed before each survey
(Table 4.5-6). Price AA current meter accuracy was tested by performing a timed spin test in
accordance with USGS (1999) protocols with results recorded in a current meter accuracy test
log. Accuracy of hand-held temperature probes was tested prior to field use in controlled water
baths using a National Institute of Standards and Technology thermometer as a control (Dunham
et al. 2005). Dissolved oxygen and conductivity probe accuracy was tested using known 0
percent oxygen (sodium sulfite) and 100 percent oxygen (water-saturated air) solutions as per the
instrument manufacturer. Turbidity meters were checked for accuracy prior to each use using
multiple turbidity standards that encompass a wide range of turbidity values (< 0.1 NTU to 800
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NTU). All data were recorded on waterproof data sheets to ensure consistent data collection
between surveys.
4.5.1.6. Juvenile Rearing and Resident Holding Utilization Surveys
To ensure the accurate detection of microhabitat use of rearing and holding fish, a combination
of active and passive fish observation methods were employed during the 2013 surveys. These
methods included snorkel surveys, pole/beach seining single-pass backpack electrofishing, and
backpack electrofishing combined with a mobile downstream block seine. Active capture
techniques were mainly used in reaches with turbid water (main channels and side channels)
where underwater visibility was limited to less than 4 feet, whereas snorkel surveys were
conducted if underwater visibility exceeded 4 feet. Fish rearing and holding observation surveys
were conducted by teams of two or three individuals with extensive experience in using fish
capture methodologies, identifying juvenile fish species, and conducting habitat and water
quality surveys. A general description of each of the sampling methods used is presented below.
4.5.1.6.1. Snorkel Surveys
Snorkel surveys were conducted at sampling sites with good (>4 feet) underwater visibility.
Prior to each survey underwater sight distance was evaluated to determine the visibility corridor
for sampling. An object was held underwater by the data recorder, and a tape measure extended
from the snorkeler to a point where the object was no longer clearly visible. As a general rule,
when visibility conditions were less than 4 feet, no underwater sampling occurred.
To ensure accurate estimation of fish size underwater, snorkelers calibrated their sights to a ruler
held underwater at various distances. Ruler marks were made on diving gloves to maintain
accuracy in the underwater estimation of fish length. Observation sites consisted of individual
fish holding in one location, but could contain a school of holding fish if the school was
composed of one species and life stage, and was thought to be using a homogenous microhabitat
site. Starting at the lower/downstream point within a longitudinal sample transect, one snorkeler
moved in an upstream direction toward the upstream end of the sample site, but making lateral
movements or zigzags as needed to cover the channel width. At each fish-use observation site,
the snorkeler placed a weighted flag and communicated the following information to the data
recorder:
• Fish species
• Fork length (mm)
• Number of fish observed for schooled-fish observations (schools categorized by life stage
and species). (Note: only one observation of microhabitat use was recorded for each
species of fish observed regardless of the number present.)
A trailing crew member then followed behind the snorkeler, being careful not to interfere with
snorkel observations, and recorded the following measurements at each fish-use observation site:
• Fish location (Lat/Long GPS location for individual or groups of measurements) and
distance from downstream end of sample site and distance from water’s edge (nearest
foot)
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• Water depth (nearest 0.1 foot) using a top setting rod
• Mean column velocity (feet per second to nearest 0.05 fps) measured using a Price AA
current meter
• Distance to water’s edge (feet)
• Substrate composition (dominant, sub-dominant, percent dominant, and percent
embedded) characterized in accordance with a Wentworth grain size scale modified to
reflect English units (Table 4.5-5).
• Water temperature (ºC)
• Dissolved oxygen (ppm)
• Conductivity (µS)
• Presence (within 1 meter) of habitat structure/cover features (e.g., boulder, wood debris,
aquatic vegetation, undercut bank, and overhanging vegetation)
All data were recorded on waterproof data sheets to ensure consistent data collection between
surveys. Accuracy of instruments used in association with snorkel observations was tested as
described for equipment used in spawning observations (see ISR Study 8.5, Section 4.5).
4.5.1.6.2. Pole/Beach Seining
Pole seining was generally used in turbid water areas that could not be sampled with underwater
techniques due to visibility limitations. Pole/beach seine nets (40 x 4 feet, 3/16 in body mesh,
1/8 in cod end mesh) were used in relatively shallow (<3.0 feet), low-moderate velocity (0 to 2
fps) locations to capture fish and determine their microhabitat use. The seine was worked
upstream and to the stream margin where captured fish were separated into species and life stage,
then released downstream after being measured.
Seine operators worked carefully to ensure that the lead line was pulled flush along the bottom of
the stream to prevent fish from escaping under the net, and to keep the cod end open. The field
crew lead estimated the point within the seine sample quadrant at which captured fish were
assumed to be holding, and thus where fish use microhabitat variables were to be measured. In
general, fish holding points were estimated as the approximate center point of the quadrant. The
area of each quadrant varied for each sampling location, but ranged from approximately 50 to
200 square feet.
4.5.1.6.3. Single-pass Backpack Electrofishing
Single-pass backpack electrofishing was used in shallow water habitats (<2.5 feet) in areas
associated with woody debris or aquatic vegetation where seining would not have been an
effective method to capture fish. The electrofishing unit was operated and configured with
settings consistent with guidelines established by NMFS (2000) and Smith-Root (2009) for safe
and effective capture of fish. One crew member electrofished approximately 10- to 25-square-
foot quadrants set approximately 10 to 30 lineal feet apart in an upstream direction. A second
crew member was positioned downstream of the electrodes with a dip net to capture stunned fish.
Captured fish were separated by species and life stage, and released downstream after being
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measured to total length. Microhabitat measurements were collected at each observation site
using methods similar to seining; however, the electrofished quadrant generally did not exceed
25 square feet.
4.5.1.6.4. Backpack Electrofishing with a Mobile Downstream Block Seine
Backpack electrofishing with a mobile downstream block seine was used in relatively deep (0.5
to 2.5 feet) and moderately high velocity (0.5 to 1.5 fps) habitats located within the sample site to
capture fish and determine their microhabitat use. One crew member electrofished
approximately 25- to 50-square-foot quadrants upstream of the blocking seine net that was set up
to capture stunned fish floating or moving downstream. Captured fish were separated by species
and life stage, then released downstream after being measured. Habitat measurements were
collected at each observation site using methods similar to seining surveys.
4.5.1.7. Habitat Availability Data Collection
After fish sampling was complete, habitat availability measurements were completed within each
sampled site. Cross-channel transects were marked every 10 meters (32.8 feet) along the edge of
the sampling site so that there would be 10 transects in each 100-meter (328-foot) site and 5
transects in each 50-meter (164-foot) site. At each transect, microhabitat measurements were
collected at three random stations across the sampled width of the channel. A random number
table was used to determine the location of each measurement across the transect. The following
measurements were made at each station across the transect:
• Water depth (nearest 0.1 foot) using a top setting rod
• Mean column velocity (feet per second to nearest 0.05 fps) measured using a Price AA
current meter
• Substrate composition (dominant, sub-dominant, percent dominant, and percent
embedded) characterized in accordance with a Wentworth grain size scale modified to
reflect English units)
• Habitat structure or cover types (if present) were noted (boulder, wood debris, aquatic
vegetation, undercut bank, and overhanging vegetation)
• Vertical hydraulic gradient, water temperature (to nearest 0.1°C), dissolved oxygen
(ppm), and conductivity (µS) measurements were made at the lower, middle, and upper
ends of each sampling site
4.5.1.8. Habitat Utilization Frequency Histograms/HSC/HSI Curve Development
The HSC/HSI habitat data collected from each site were entered into spreadsheets and checked
for data entry accuracy. For each species and life stage, frequency distributions were then
generated for mean velocity, depth, and dominant substrate type for each species and then
normalized to the maximum values of each parameter. Histogram plots of depth and mean
column velocity utilization were developed using bin sizes of 0.2 for both water depth and
velocity microhabitat data. The frequency of fish observations in each of the bins was then
normalized by dividing by the maximum value observed, to create probability histograms with
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values between 0 and 1. These histograms were then compared to 2012 utilization histograms
and to the 1980s HSC/HSI curves, which were based on utilization and presented in R2 (2013e).
Where possible, the 2013 HSC/HSI utilization data, along with additional utilization data
collected during the next year of study will be combined with habitat availability observations to
compute habitat preference curves (ISR Study 8.5, Section 4.5). This analysis will evaluate the
probability of observing a fish of a given species and life stage in a particular location, given the
depth, velocity, substrate, and other microhabitat variables available at that location. These
relationships will be modeled using logistic regression, and where appropriate univariate and
multivariate statistical methods.
4.5.1.9. Other Methods for HSC/HSI Curve Development
For some species and life stages, the 2013 site-specific HSC/HSI curves discussed above may be
used as final curves. However, additional HSC/HSI sampling is planned for the next year of
study and it is anticipated that most HSC relationships will be updated. For species and life
stages that are rarely observed, final HSC curves may be based on additional data, including
utilization data from 2012 and the 1980s studies on the Susitna River. However, there may still
be some species where few or no empirical HSC/HSI data were able to be collected. In those
cases, AEA will consider other methods for developing curves. This may include the use of
literature based curves, developing envelope curves (see, for example, Jowett et al. 1991, and
GSA BBEST 2011), guilding (e.g., creating a combined HSC/HSI curve representing multiple
species and/or life stages; see, for example, Vadas, Jr. and Orth 2001, GSA BBEST 2011),
developing curves based on expert opinion/round table discussions) and the use of Bayesian
statistical methods for updating data distributions (see, for example, Hightower 2012).
Bootstrapping may be used as one technique for estimating variability around these types of
combined curves. Bootstrapping is a data-based simulation method for assigning measures of
accuracy to statistical estimates and can be used to produce inferences such as confidence
intervals (Efron and Tibshirani 1993).
The site-specific HSC/HSI curves developed based on the 2013 data will be presented in 2014 as
part of the Proof of Concept discussions and will include estimates of uncertainty based on
standard errors from the logistic regression model. Data collected during the next year of study
will include availability data and will be combined with the 2013 data to refit the logistic
regressions, with potential consideration of different time periods.
4.5.1.10. Winter Habitat Use Sampling
Pilot IFS winter studies were completed during 2012–2013 to monitor water quality and stage
conditions at salmon spawning locations and to record fish habitat use. These studies were done
as a collaborative effort with the FDA study (Study 9.6) and Groundwater Study (Study 7.5).
The winter IFS 2012–2013 pilot study was comprised of three components: 1) monitoring of
intergravel temperature, dissolved oxygen, and surface water levels; 2) fish behavior and habitat
use observations; and 3) winter fish capture. One of the primary purposes of the pilot study was
to evaluate and test different instruments, methods, and approaches for safely conducting winter
studies within the Middle River Segment of the Susitna River, with the goal of taking that
information and applying it to develop a more robust winter study program for 2013-2014.
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The 2012-2013 pilot winter studies were comprised of two primary components: 1) water level
and water quality monitoring and 2) fish behavior and habitat use observations. Data collection
occurred during three trips in early 2013: February 1-7, March 19-25 and April 8-13. The initial
work on the 2012–2013 pilot study consisted of a focused review of literature from 1980s studies
and of more recent research to identify potential methods for each study component.
Water level and water quality were continuously monitored at nine sites in FA-104 (Whiskers
Slough) during February – April 2013 (Figure 4.5-2). Continuous monitoring sites in FA-104
(Whiskers Slough) were established in early February 2013 in the Susitna River within a variety
of macrohabitat types. These included main channel, side channel, side slough, upland slough
and tributary habitats. The areas selected were comprised of areas with known or suspected
groundwater upwelling, bank seepage and lateral intergravel flow from the main channel, areas
of mixing between upwelling and bank seepage, areas with no intergravel discharge, areas where
fish had been observed spawning. In FA-128 (Slough 8A), continuous water level and water
quality sites were established during March 2013 in side slough and upland slough habitats
(Figure 4.5-3). Salmon spawning was observed during fall 2012 at FA-104 (Whiskers Slough)
sites WSC-30, WSL-20 and WC-10 and at FA-128 (Slough 8A) Site SL8A-15 (Figure 4.5-2 and
Figure 4.5-3). Habitat designations (e.g., side channel, slough) used during 2012-2013 winter
studies were based on 2012 Middle River Segment remote line habitat mapping (HDR 2013).
Most water level and water quality instruments were downloaded and removed prior to
completion of the April 2013 trip, however, a subset of water level and temperature instruments
were downloaded and redeployed in April 2013 to record hydrologic and temperature conditions
through spring ice breakup.
Pressure transducers (Solinst leveloggers) were used to record changes in stage at continuous
monitoring sites. Transducers were deployed at the substrate surface at each site. To prevent
shifting during the deployment period, transducers were anchored with weights and attached to
metal stakes driven into the substrate. All transducers were removed during the final data
collection period in April 2013, with the exception of instruments in Whiskers Slough) (WSL-
20) and Slough 3A (SL3A) in FA-104 (Whiskers Slough) and both sites in FA-128 (Slough 8A)
(SL8A-10 and US2-10) (Figure 4.5-2 and Figure 4.5-3). In FA-104 (Whiskers Slough),
comparisons between stage in side channel and off-channel habitats relative to the Susitna River
main channel were completed using pressure transducer data normalized to zero at the common
start time for all instruments within the FA. At FA-128 (Slough 8A), main channel stage data
were not available so stage data recorded at the USGS gage at Gold Creek (No. 15292000) after
ice breakup were used for comparison of main channel and off-channel stage. Pressure data
recorded at each continuous monitoring site was compensated with barometric pressure data
recorded at FA-104 (Whiskers Slough) and FA-128 (Slough 8A) (Figure 4.5-2 and Figure 4.5-3).
Surface and intergravel water temperatures and intergravel dissolved oxygen concentrations were
continuously recorded in FA-104 (Whiskers Slough) and FA-128 (Slough 8A) (Figure 4.5-2 and
Figure 4.5-3). Surface water temperature was recorded by pressure transducers at the substrate
surface. Intergravel water temperature loggers (Hobo Tidbit v2) were deployed at three separate
intergravel depths: 5 centimeters (cm) (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) beneath the
substrate surface. These depths reflect observed burial depth ranges of chum and sockeye eggs
(Bigler and Levesque 1985; DeVries 1997). Intergravel temperature probes were attached to
stainless steel cable and deployed into the gravel using a steel installation device (sensu
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Zimmerman and Finn 2012). Dissolved oxygen loggers (HOBO U26-001), which also recorded
water temperature, were bolted within a perforated PVC tube and likewise inserted into the
gravel to a depth of approximately 20 cm adjacent to known or historic salmon spawning areas.
All intergravel temperature and dissolved oxygen instruments were removed in April 2013
except intergravel temperature loggers at Whiskers Slough (WSL-20) and Whiskers side channel
(WSC-30) in FA-104 (Whiskers Slough), which were recovered in June 2013 and October 2013,
respectively.
The relationship between main channel stage and water temperature was evaluated at three sites
in FA-104 (Whiskers Slough) that were observed to support salmon spawning in 2012 (WSC-30,
WSL-20, and WC-10). The stage records for each spawning site and the main channel were
normalized to zero at the start of data collection and compared to surface and intergravel
temperatures.
Instantaneous measurements of surface water quality were recorded at continuous monitoring
sites in addition to other main channel and off-channel areas in FA-104 (Whiskers Slough) and
FA-128 (Slough 8A) during January, March, and April 2013 using a hand-held water quality
meter (YSI Pro 30) (Figure 4.5-2 and Figure 4.5-3). Measurements of water temperature,
dissolved oxygen concentration and specific conductance were recorded on the water surface and
at mid-column depth. Instantaneous water quality data were used to characterize surface water
quality in each Focus Area and to help discern qualitative differences in groundwater
composition among habitats based on water temperature and specific conductance (Rosenberry
and LaBaugh 2008).
Fish observation and capture efforts occurred in each Focus Area during monthly trips between
February-April 2013. Fish observation sites were located in open-water and ice-covered areas
within off-channel and tributary habitats (Figure 4.5-2 and Figure 4.5-3). Underwater video was
used consistently by FDA and IFS staff during each trip and in each Focus Area to monitor
behavior in fish communities and evaluate the effectiveness of different camera types, power
supplies, and lighting conditions. Dual Frequency Identification Sonar (DIDSON) was utilized
opportunistically by FDA staff in FA-104 (Whiskers Slough) to gauge its applicability for
monitoring fish behavior and habitat utilization during winter. When used in ice-covered areas,
the video camera or DIDSON unit was lowered through auger holes drilled through the ice.
Where possible, video cameras were used to characterize winter habitat attributes such as the
presence of anchor ice, hanging dams, and substrate type.
Electrofishing surveys were performed during 2012-2013 IFS winter studies to collect site-
specific habitat suitability criteria (HSC) data and augment observations of fish behavior.
Electrofishing surveys were conducted at four sites in open-water areas of FA-104 (Whiskers
Slough) and FA-128 (Slough 8A) during day and night surveys in March and April 2013 (Figure
4.5-2 and Figure 4.5-3). HSC/HSI data (e.g., velocity, water depth, substrate and cover) were
measured at the point of fish capture during electrofishing sampling and in association with
underwater video monitoring provided fish species and size could be determined during
underwater surveys and target fish were observed maintaining a stationary position. Water
velocity and depth measurements were made either through holes drilled in the ice or in open-
water leads using a wading rod and Price AA water velocity meter. Instantaneous measurements
of water temperature, dissolved oxygen and specific conductance were recorded using a hand-
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held water quality meter (YSI Pro 30) to describe water quality conditions at the location of fish
observations.
4.5.1.11. Stranding and Trapping
No formal stranding and trapping surveys were conducted during the 2013 field season. The
need for, and if warranted the type of, such surveys to be completed during the next year of study
will be determined.
4.5.1.12. River Productivity
Development of HSC/HSI for macroinvertebrates and algae followed a similar general approach
to that for fish, and included a literature search for available information, field studies to
supplement literature-based information and to provide site-specific data, and use of a panel of
TWG participants to finalize the HSC/HSI curves. The development of HSC/HSI information
for macroinvertebrates and algae is one part of the more comprehensive River Productivity Study
(Study 9.8).
In 2013, macroinvertebrate sampling was stratified by reach and mainstem macro-habitat type
(mainstem, tributary confluences, side channels, and sloughs). Sampling stations were located at
FA-104 (Whiskers Slough), FA-141 (Indian River), FA-173 (Stephan Lake Complex), and FA-
184 (Watana Dam). One additional station was located in the Lower River Segment near
Montana Creek (RP 81). Sampling occurred at five stations, with 3-5 sites each (depending on
the number of macrohabitats present in the Focus Areas) for a total of 20 sites. See ISR Study
9.8 for locations of sample sites. Measurements of depth (measured with top-set rod), mean
water column velocity (Pygmy current meter), and substrate composition (visual assessment)
were taken concurrently with benthic macroinvertebrate sampling.
Data collected in 2013 will be used to develop histograms (i.e., bar charts) for each of the
habitat parameters (e.g., depth, velocity, substrate, frequency of dewatering) for
macroinvertebrates and algae. The histograms developed using field observations from 2013
will then be compared to the literature-based HSC/HSI curves to validate applicability of the
literature-based HSC/HSI curves for aquatic habitat modeling.
4.5.1.13. Periodicity
Fish periodicity describes the temporal and spatial utilization of mainstem, off-channel, and
tributary habitats in the Susitna River by individual fish species and life stages and is necessary
to evaluate potential effects of Susitna River streamflow fluctuations on fish communities. In
2013, AEA developed 14 separate species and life-stage-specific periodicity tables applicable to
different segments and macrohabitat types of the Susitna River (see Tables 5.1-1 through 5.1-14
in R2 2013e). The species covered included Chinook, coho, sockeye, chum, and pink salmon;
rainbow trout; Arctic grayling; Dolly Varden; burbot; round and humpback whitefish; longnose
sucker; Bering cisco; and eulachon. These tables were based on information provided in the
1980s studies as well as more contemporary information from ADF&G reports (e.g., Merizon et
al. 2010). Additional species periodicity information has been collected in 2013 as part of the
IFS HSC/HSI studies (ISR Study 8.5, Section 4.5.1.13) and a number of fish studies including
Fish Distribution and Abundance in the Middle and Lower River (Study 9.6), Salmon
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Escapement (Study 9.7), Eulachon (Study 9.16). Updates and/or revisions to the draft
periodicity tables will be completed in cooperation with fisheries resource leads and the TWG in
2014.
4.5.1.14. Biological Cues Study
Climatic and hydrologic patterns are important considerations in determining salmon distribution
and abundance. Large-scale climatic changes (e.g., Pacific Decadal Oscillation) affect regional
weather conditions that subsequently influence hydrologic conditions (Hartmann and Wendler
2005). Changes in river hydrology can influence the stability and persistence of aquatic habitats
and can determine fish distribution and abundance (Connor and Pflug 2004). The objective of
this exploratory analysis was to look for general relationships between temporal patterns in
environmental conditions and salmon distribution, abundance, and migration timing. Analyses
of these flow-dependent biological cues, such as possible relationships between climatic,
hydrologic, and fish habitat indices and salmon abundance and migration timing, were to be
based on available long-term datasets for Deshka River Chinook salmon and Yentna River
sockeye salmon. Other Susitna River Basin long-term datasets pertaining to salmon migration
timing and abundance were to also be included if available.
After examination of data reports and available hydrologic data, and discussions with ADF&G
personnel, the Deshka River and the Yentna River were ruled out as plausible datasets to
examine relationships between hydrology and biological response relevant to Susitna River
salmon stocks. Through further discussions with ADF&G, AEA selected the Taku River and
Stikine River Chinook salmon stocks for this study. These two systems were selected because
both are glacial fed systems like the Susitna, both support populations of Chinook salmon that
have been monitored by ADF&G for several decades, and both have a long hydrologic record
from which to test for biologically relevant hydrologic metrics.
Biological data focused on Chinook salmon harvest levels and smolt and adult abundance levels
for the Taku and Stikine rivers that were acquired from ADF&G (R. Phillips, ADF&G biologist,
personal communication, September 6-12, 2013). Data collection methods are described in
McPherson et al. (2010) for the Taku River and in Richards et al. (2012) for the Stikine River.
For each river, annual data consisted of the following:
• Harvest levels downstream of the fish-counting station
• Harvest levels upstream of the counting station
• Inriver run size at the counting station
• Inriver age structure (percent of run in ages 3-7)
• Smolt abundance by brood year
Hydrologic data focused on daily flow values acquired from USGS gages located in the lower
Stikine and lower Taku rivers (Gage No. 15024800 and Gage No. 14041200). PDO data were
acquired from the University of Washington Joint Institute for the Study of the Atmosphere and
Ocean (UWJISAO 2013). The hydrologic data were initially analyzed using The Nature
Conservancy’s (TNC) Indicators of Hydrologic Alteration (IHA) and Environmental Flow
Component (EFC) software (TNC 2009). This resulted in the calculation of 33 IHA metrics and
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34 EFC metrics for each system. The outputs were subsequently post-processed in Excel to
compute flow metrics specific to the life history characteristics of Chinook salmon.
For Chinook salmon productivity, daily flow values were summarized over periods considered
potentially critical for survival during egg incubation, winter rearing, summer rearing, out-
migration, and early ocean rearing (see Table 2 from Biological Cues ISR Study 8.5, Appendix
B). In addition, Mantua et al. (1997) demonstrated a relationship between the PDO in sea
surface temperatures with the productivity of salmon stocks in Alaska and the west coast of
North America. Consequently, a PDO index was also included in the pool of potential
covariates. For median run timing two potential flow indices were considered as potential
covariates while three indices were considered for run duration (see Table 3 from Biological
Cues ISR Study 8.5, Appendix B).
If relationships among these variables exist, they are likely to be highly complex and interactive.
This study was based on available data only, and is not meant to be exhaustive. Rather, AEA
looked for moderate correlations and evaluated relationships visually and using regression
analysis. Linear and local regression analysis was used to visually discern potential linear and
non-linear relationships between select biological and hydrologic variables. Correlation
estimates were obtained for each paired relationship with a potentially meaningful causal
mechanism based upon an understanding of mechanisms observed in other systems. For
relationships that had moderate correlations, we examined relationships further with single or
multiple linear regressions, including two-way interactions, and described the best-fitting model.
A detailed description of the methods used as part of this analysis is provided in ISR Study 8.5,
Appendix B (Biological Cues Study).
4.5.1.15. Relationship between Microhabitat Use and Fish Abundance
In the April 1, 2013 Study Plan Determination (FERC 2013b), FERC recommended that the
following additional variables be compared to fish distribution and abundance: surface flow and
groundwater exchange fluxes, dissolved oxygen (intergravel and surface water), macronutrients,
temperature (intergravel and surface water), pH, dissolved organic carbon, alkalinity, and
Chlorophyll-a. If strong relationships are evident between fish habitat use and any of these
variables, FERC suggested that additional HSC preference curves may need to be developed for
the various species and life stages.
AEA initiated this evaluation in Q4 2013 by first identifying and reviewing the extent and
completeness of the data necessary to complete the analysis. This review revealed that the
following information was already or would be soon available to be used in the analysis,
organized by study:
• River Productivity – data have been collected during three separate sampling events
(spring, summer, fall) within FA-104 (Whiskers Slough), FA-141 (Indian River), FA-173
(Stephan Lake Complex), and FA-184 (Watana Dam). Finalized turbidity,
photosynthetic active radiation, and temperature data available Q4 2013.
• Groundwater – spot and continuous records collected during winter and summer
sampling events within FA-104 (Whiskers Slough), FA-115 (Slough 6A), FA-128
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(Slough 8A), and FA-138 (Gold Creek). Limited availability of finalized water quality
data in Q4 2013. Remaining data finalized next year of study.
• Water Quality – collected during three separate sampling events (July 28, August 11, and
August 23) within seven Focus Areas located downstream of Portage Creek. Limited
availability of finalized water quality data in Q4 2013. Remaining data finalized next
year of study.
• Fish Distribution and Abundance - collected during three separate sampling events (July
7-August 12, August 13-September 4, September 4-October 4) from representative
habitat types within each FA. Limited availability of finalized fish distribution and
abundance data in Q4 2013. Remaining data finalized next year of study.
Once all data are compiled, AEA will complete a statistical analysis of the data to detect possible
relationships between one or more of the variables and fish distribution and abundance
information. The analysis proposed for completing this evaluation is described in ISR Study 8.5,
Section 7.5.
4.5.2. Variances from Study Plan
AEA implemented the methods as described in the Habitat Suitability Criteria Development
section of the Study Plan with the exception of the variances explained below.
• Due to access restrictions, the distribution of HSC sampling sites in the Middle River
Segment was limited to habitat areas between Portage Creek (PRM 151.8) and Three
Rivers (PRM 102.4). The Study Plan states: “sample sites will be stratified and randomly
selected from within the Middle River Segment (RM 98-RM 184) and Lower River
Segment (RM 77¬RM 98) of the Susitna River”. However, no HSC sampling sites were
selected within the Lower River due to delays in completing habitat composition surveys
and the desire to concentrate the 2013 sampling effort within the Middle River. These
changes are not anticipated to adversely impact achieving Project objectives assuming
that these areas will be sampled during the next year of data collection.
• Spawning redd dimensions were not collected as part of the 2013 HSC spawning surveys.
The Study Plan states “Redd dimensions (length and width in feet to nearest 0.1 foot) will
be collected.” Redd dimension measurements were recorded as part of the 2012 HSC
surveys. Additional redd measurements were not deemed necessary to develop
evaluation metrics. This change is not anticipated to adversely impact achieving Project
objectives as spawning redd dimensions are not an input variable in the FA-IFS habitat
modeling.
• Substrate composition was simplified to include only two gravel size classes (small and
large). The Study Plan states: “Substrate size (dominant, sub-dominant, percent
dominant) characterized in accordance with a Wentworth grain size scale modified to
reflect English units.” Field personnel found it impracticable to attempt to accurately
differentiate gravel composition into three size classes in turbid water conditions. Using
two size classifications to describe gravel is consistent with substrate classifications used
on numerous other HSC/HSI curve development studies and is not anticipated to impact
HSC/HSI curve development.
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• Only one velocity measurement (mean column) was recorded for each individual fish
microhabitat use observation. The Study Plan states “Location in water column (distance
from the bottom), focal point and mean column velocity (feet per second to nearest 0.05
fps) measured using a Price AA current meter”. Most fish captures occurred using
electrofishing, seining or a combination of the two methods which precluded the
identification of fish focal point position within the water column. The IFS habitat
models rely on mean column water velocities and therefore not measuring focal point
velocity will have no adverse impacts on HSC/HSI development or on the habitat
modeling.
• Mesohabitat type was not recorded for fish observation/capture points. Mesohabitat
mapping was completed as part of RSP 9.9 and the data are currently being analyzed
(Study 9.9). After the mesohabitat mapping task is complete, GIS data layers containing
the location of HSC/HSI fish use observations will be compared to GIS data layers
containing mesohabitat types to determine mesohabitat use by individual fish species and
life stages. This change will not adversely impact Project objectives.
• The Study Plan indicated that “field surveys will be conducted at potential stranding and
trapping areas on an opportunistic basis following up to three flow reduction events
during 2013.” During a May 17, 2013 Technical Team meeting, participants indicated
that site-specific stranding and trapping studies should be a low priority. Because the
Project does not yet exist, the effects of Project-induced flow fluctuations cannot be
directly studied in the Susitna River. Some opportunistic observations of potential
stranding and trapping areas were recorded during substrate classification surveys
conducted during falling river stage conditions in September 2013, but the observations
did not follow robust survey protocols. Although specific stranding and trapping surveys
were not conducted in 2013, this change is not expected to adversely impact achieving
Project objectives. AEA will discuss the need for stranding and trapping surveys with the
resource agencies during TWG meetings. If stranding and trapping surveys are not
needed, ramping criteria developed in Washington State (Hunter 1992) will be proposed
as fallback criteria during effects analyses. This was noted during the May 17, 2013
TWG meeting.
• According to the Study Plan for winter sampling, results of the 2012-2013 winter effort
were to be distributed to TWG participants by Q3 2013. Although condensed results
from winter data collection were communicated to TWG participants during IFS
presentations at quarterly TWG meetings in June, September and December 2013,
detailed results were not distributed due to IFS data collection and analysis activities that
occurred during Q3 and Q4 2013. AEA will distribute a technical memorandum that
describes the results of the IFS pilot winter studies to the stakeholders for review and
comment in 2014.
• The Study Plan indicated that macroinvertebrate “sampling will occur at six stations,
each with three sites (one mainstem site and two off-channel sites associated with the
mainstem site), for a total of 18 sites. River Productivity sampling occurred at five
stations on the Susitna River, each station with three to five sites (establishing sites at all
macrohabitat types present within the station), for a total of 20 sites. Four stations were
located in Focus Areas (FA-184 [Watana Dam], FA-173 [Stephen lake Complex], FA-
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141 [Indian River], and FA-104 [Whiskers Slough]). Station RP-81 is located in the
vicinity of the mouth of Montana Creek. This change will not adversely impact
achieving Project objectives since the greater sample coverage per site offsets the
reduction of one site.
• The FERC-approved Study Plan for the Biological Cues Study indicated Deshka River
Chinook salmon and Yentna River sockeye salmon datasets would be examined for flow-
dependent biological cues. Mainly due to the lack of the necessary data, the Deshka
River and the Yentna River were not used for this study. As noted above (ISR Study 8.5,
Section 4.5.1.1.14), through discussions with ADF&G, the Taku River and Stikine River
Chinook salmon stocks were selected and the analysis completed.
• As part of the FERC-approved Study Plan, FERC recommended that the following
additional variables be compared to fish distribution and abundance: surface flow and
groundwater exchange fluxes, dissolved oxygen (intergravel and surface water),
macronutrients, temperature (intergravel and surface water), pH, dissolved organic
carbon, alkalinity, and Chlorophyll-a. If strong relationships are evident between fish
habitat use and any of these variables, FERC suggested that additional HSC preference
curves may need to be developed for the various species and life stages. Most of the data
necessary to complete this analysis is still being processed and/or undergoing quality
assurance checks and is not available at this time. AEA initiated this task in Q4 2013 and
will complete the analysis in the next year of study. This change in schedule is not
expected to adversely impact achieving Project objectives since there will be adequate
time for agency review and comment prior to the start of the next year of data collection.
4.6. Habitat-Specific Model Development
AEA implemented the methods related to habitat model development for both the Middle and
Lower River segments of the Susitna River as described in the Study Plan. There were no
variances pertaining to the Middle River Segment, but a few variances occurred relative to the
Lower River Segment that are described in ISR Study 8.5, Section 4.6.2. As described in the
Study Plan schedule of activities, most habitat modeling activities will occur after the ISR is
submitted in 2014. Thus, the work completed in 2013 consisted largely of activities associated
with the selection of specific models to be used, coordination with other resource model leads in
the completion of surveying and collection of field data necessary to support model
development, preliminary model development, and completion of preliminary model test-runs to
illustrate draft habitat evaluation metrics and linkages with other resource models.
The habitat-specific models represent the core analytical tools that will be used to first,
determine the relationships between the amount of streamflow and the quantity and quality of
physical habitats of fish at different locations in the Susitna River and during different times, and
second, using those relationships in combination with outputs from other resource models
evaluate the effects of different Project operations on those habitats. The RSP 8.5 (Section
8.5.4.6) provided background information on the types and intended uses of the habitat models
that will be applied in this analysis and is not repeated in this ISR. The methods and models
include a combination of approaches that vary 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
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conditions in the habitats, etc.) Importantly, the habitat-specific models are only one of a number
of resource models that will be used for evaluating Project effects on aquatic and fish habitats.
Other models are being developed to address issues related to:
• Water quality: models include – (3-D) Reservoir Water Quality Model, (2-D) River
Water Quality Model, and (2-D) River Water Quality Model with Enhanced Resolution
Focus Areas (Study 5.6),
• Sedimentation and channel morphology: models include – 1-D Bed Evolution Model, 2-
D Bed Evolution Model (Study 6.6)
• Ice processes and under ice conditions: models include – River1D Ice Processes Model,
River2D Focus Area Ice Models (Study 7.6), and
• Groundwater and surface water interactions: models include – empirical models based on
groundwater level-surface water level monitoring, MODFLOW for selected Focus Areas
(Study 7.5).
As will be described in ISR Study 8.5, Section 4.8, the habitat-specific models will depend on
outputs from the Reservoir Operations Model and the Open-water Flow Routing Model and
River 1D/2D Ice Processes Models to evaluate project effects on physical habitats during open-
water and ice-covered conditions. The other resource models will be integrated into the analysis
as needed to address specific biologically relevant questions.
4.6.1. Methodology
The development of the habitat-specific models was tailored around the study sites and transect
locations identified in ISR Study 8.5, Section 4.2. These sites consisted of the ten Focus Areas
selected in the Middle River Segment (Table 4.2-3), and the study sites and transect locations
selected in the Lower River Segment (Figure 4.2-11 and Figure 4.2-12). The Lower River sites
were selected following an aerial reconnaissance (completed on May 16, 2013) of the tributary
mouths and main channel habitat areas around Trapper Creek (PRM 95.4), Birch Creek (PRM
93.3), Caswell Creek (PRM 67.3), and Sheep Creek (PRM 71.7). Fish habitat transects were
identified in the vicinity of Trapper Creek and Birch Creek to capture the habitat conditions at
the tributary mouth and within adjacent mainstem macrohabitats. Fish habitat transects were
also identified between PRM 95 and PRM 97 to capture mainstem macrohabitat types for the
Lower River. Transect selection and measurements for the Deshka River and boundary
condition transects for Trapper Creek were collected as part of the Fluvial Geomorphology Study
(ISR Study 6.6).
4.6.1.1. Habitat Model Selection
The selection of specific habitat models was made following discussions with the agencies and
stakeholders that began in 2012 as part of the August 16, September 14, and October 2-3 TWG
meetings. During the latter meeting, AEA reviewed a variety of instream flow methods and
models for potential applicability on the Project (
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Table 4.6-1). As part of the October meeting AEA completed a two-day site reconnaissance
with personnel from state and federal agencies, Alaska Native entities, and other TWG members
to review river reaches and habitat types, visit several proposed Focus Areas, and discuss options
for model development. Participants reconvened for a field reconnaissance debrief on the final
day of the trip to discuss observations and assessment of different modeling methods. At that
time, consideration was being given to the application of either 1-D or 2-D hydraulic models
coupled with habitat models that would be used within a Physical Habitat Simulation
(PHABSIM) based framework, as well as several other models (Table 4.6-1). Based on further
internal discussions between resource leads, it was decided that 2-D hydraulic modeling would
provide the greatest resolution for defining habitat-flow relationships and sediment transport
relationships within Focus Areas of the Middle River Segment. This was discussed during the
February 14, 2013 TWG meetings (Tetra Tech 2013e) and AEA subsequently proceeded with
data collection to support development of 2-D models in the Focus Areas. However, due to the
complexity of the channel network in the Lower River Segment, AEA selected the 1-D hydraulic
model HEC-RAS Version 4.1 to simulate water surface elevations coupled with PHABSIM for
modeling habitats at discrete locations, and proceeded with data collection for those models (R2
2013b). Details concerning the collection of data to support development of these models are
provided in the following sections.
4.6.1.2. Field Coordination and Collection of Physical and Hydraulic Data
Once Focus Areas (Middle River Segment) and transect locations (Lower River Segment) were
identified, and the habitat-specific models selected, detailed field surveys were conducted.
These surveys occurred in 2013 and were closely coordinated between and among the different
resource leads to ensure that data necessary for developing the respective models was being
collected. This was especially important relative to the surveying and data collection in the
Focus Areas for the development of the 2-D hydraulic models. Those data were collected as part
of the FA-IFS program but are being analyzed for development of the 2-D hydraulic models by
the Geomorphology program (Study 6.6). Once the 2-D hydraulic models are developed, FA-
IFS will then apply the models in a 2-D PHABSIM framework to define habitat – flow
relationships and other habitat metrics (ISR Study 8.5, Section 4.6.1.4).
During 2013, physical and hydraulic data collection within the Middle River Segment included
measurement of hydraulic boundary conditions, stage and discharge measurements, bathymetric
surveys, velocity mapping, and roughness (channel substrate) determinations at seven Focus
Areas: FA-104 (Whiskers Slough), FA-113 (Oxbow 1), FA-115 (Slough 6A), FA-128 (Slough
8A), FA-138 (Gold Creek), FA-141 (Indian River), and FA-144 (Slough 21). Data were also
collected from Middle River cross-sections established to support development of the Open-
water Flow Routing Model (ISR Study 8.5, Section 4.4).
For the Lower River Segment, each transect was initially flagged and marked with a hand-held
GPS to identify the headpin location for the survey crew. Data collection included single
transect surveys consisting of ADCP measurements for discharge determinations, stage
measurements, and bathymetric surveys. completed using the protocols described in ISR Study
8.5, Appendix A.
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4.6.1.2.1. Boundary Condition Transects
The upstream and downstream boundaries as well as the lateral extents of the Focus Areas were
established by the Geomorphology Study (RSP Section 6.6.4.1.2.4) in 2013 so that appropriate
boundary condition transects could be established for the 2-D hydraulic modeling.
Data were collected at each of the boundary condition transects as part of the hydrologic data
collection field activities described in ISR Study 8.5, Section 4.3. The primary field data
collected at each of the transects included:
• Completion of a cross-section survey to define channel topography and hydraulic
controls at the upstream- and downstream-most portion of each Focus Area using
RTK GPS instrumentation.
• Velocity and discharge measurements collected using an ADCP system consisting of
a Sontek M9 equipped with RTK GPS positioning to generate the necessary discharge
and velocity distribution data (ISR Study 8.5, Appendix C).
• Measurement of the water surface elevation during discharge measurements, and
documentation of the substrate type, groundcover, habitat type, and woody debris in
the flood-prone area for the purposes of developing roughness estimates.
• Measurement of stage and discharge during a high and low flow condition.
Data collected at each of the boundary condition transects will be used to compute the energy
slope, velocity, depth, and other hydraulic variables at each cross-section for use in development
of the 2-D hydraulic models.
4.6.1.2.2. 2-D Modeling
In 2013, AEA collected bathymetric data within each of the seven measured Focus Areas as part
of the hydrologic data collection activities described in ISR Study 8.5, Section 4.3. The data
were collected with a Sontek M9 ADCP and vertical-beam depth sounder and RTK GPS
positioning systems. These data will serve as input to the 2-D hydraulic models that are being
developed and described in the Geomorphology study (ISR Study 6.6). AEA performed cross-
sectional bathymetric surveys as part of discharge measurements completed in 2012 and 2013
using the AEA used the results of these surveys to prepare a digital elevation model of the
streambed., AEA used the digital elevation model together with shore-based RTK GPS surveys
to develop cross-sections for use in the Open-water Flow Routing Model.
The bathymetric surveys were conducted in both deep (via boat) and shallow (by wading) water
areas along pre-planned survey lines throughout the seven Focus Areas. An example of the
pattern and density of the measurements is presented in ISR Study 6.6. The survey lines were
selected using recent imagery and hydrographic data acquisition software (e.g., HyPack); the
density of survey lines was commensurate with the minimum model grid spacing needed for 2-D
hydraulic or other IFS models (ISR Study 6.6).
The bathymetric data were QA/QC checked and post-processed using hydrographic data
software to obtain a digital terrain model from which a Triangulated Irregular Network (TIN)
was derived. The digital terrain models and TIN were used to develop cross-sections or as input
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to the 2-D hydraulic models and other instream flow models. The ADCP files were post-
processed to develop cross-sectional or plan-view velocity maps for calibration of hydraulic
models.
As part of the surveys, AEA visually estimated substrate size and composition by wading in
shallow areas or probing in deeper water main channel areas. The same substrate categories as
used for the HSC data collection were applied during the surveys. Visual calibration of the size
classes was made prior to the data collection by having each observer estimate substrate size
classes within a given area and then measuring the substrate. This calibration procedure was
repeated periodically each day by all observers at each Focus Area. The substrate categories
(dominant particle size, subdominant and percent dominant) were recorded on laminated
enlarged aerial photographs as polygons or point values on cross-sections. AEA categorized
main channel substrate in cross-sections by probing with a long rod over the side of a jet boat.
Cross-sections were repeated at regular intervals in each Focus Area. The combined data
collection of shoreline crews and boat crews resulted in a complete substrate survey of each
Focus Area.
4.6.1.2.3. Single Transect Data Collection
Single transect cross-sections were located and measured in 2012 and 2013 in both the Middle
and Lower River segments as described in the hydrologic data analysis section of ISR Study 8.5,
Section 4.3. Data collected from these transects has and will continue to be used to support
development of the Open-water Flow Routing Model as well as for collecting discharge and
stage information. Data from some of these cross-sections may also be used in a 1-D PHABSIM
type analysis.
The need for doing so in the Middle River Segment will be determined based on results obtained
from the Focus Area 2-D habitat-flow modeling. The 2-D hydraulic model domain includes the
entire riverine (wetted) spatial area of each Middle River Focus Area and therefore can be used
to evaluate features and attributes using single transect modeling. If 1-D, single transect
modeling is required in the Focus Areas, the data can be extracted from the 2-D model domain
and the field survey data used to construct those models. The transects outside of the Focus
Areas can also be brought into this analysis if supplemental information is needed.
In the Lower River Segment, in addition to the cross-sections established for discharge
measurements and the Open-water Flow Routing Model, single transects were located across a
range of macrohabitat types at five sites established between PRM 92.9 and PRM 97 to support
development of 1-D hydraulic models and completion of a 1-D PHABSIM analysis. Data
collection at those sites consisted of three site visits (June, August and September 2013) to
coincide with high, moderate and low flow conditions. Flow conditions for each field visit were
assessed based on real-time flows reported for the Susitna River at the Sunshine gage (USGS
Gage No. 15292780). The flow target for collecting field data under high flow conditions was
greater than 80,000 cfs, the moderate flow target was around 50,000 cfs and the low flow target
was less than 25,000 cfs. Each of the three surveys was completed near the targeted flow ranges.
From 3 to 17 cross-sectional transects were established per site in June 2013 (Figure 4.2-11).
Data collection was completed in accordance with methods described in ISR Study 8.5, Section
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4.3 and ISR Study 8.5, Appendix C and included ground surveying using an RTK GPS, and
bathymetric surveys and velocity measurements using an ADCP. Field protocols specified the
collection of one complete set of velocity profiles, bathymetry and water surface elevation data
at each transect and representative discharge measurements to establish boundary conditions for
a single flow condition. The field survey protocols for the remaining two flow conditions
involved the collection of water surface elevation data at each transect and completion of
substrate and cover mapping. This approach assumes that the same bed topography will be
applied for each discharge condition and as part of the data analysis required the flow routing
model results and USGS discharge data for the mainstem and tributary gages to establish
boundary conditions to support the field data collected during the two follow-up field surveys.
Representative photographs were taken during each of the three flow conditions at each transect
showing views upstream, downstream and facing both banks.
The high flow survey was completed from June 10 to June 15, 2013 at flows ranging between
approximately 70,000 cfs and 90,000 cfs as measured at the Susitna River at the Sunshine gage
(USGS Gage No. 15292780) (provisional). During the June survey, initial site set-up was
completed with installation of transect headpins. The bathymetric survey, velocity profile
measurements and water surface elevation survey were completed for high flow conditions at
each transect. Transects were marked on both banks with re-bar pins, labelled survey lath and
flagging tape. An additional marker pin was installed approximately 300 meters upstream of the
PRM 96 site on the right bank of the main channel to serve as a main channel water level
reference at the time of the survey. The RTK GPS topographic survey was conducted in June to
collect location and elevation of water level data at wetted edges, marker pins, bank
characteristics and streambed sections that were dry or too shallow to be captured by the boat-
mounted ADCP crew. Discharge and bathymetry data were collected with ADCP for each
transect in June 2013, with the exception of a single transect within the Trapper Creek site that
was too shallow to survey by boat. At this location, depths and velocities were measured using a
Sontek FlowTracker velocimeter mounted to a top-set wading rod. The distances along the
transect were established using a tape measure and were identified relative to the headpin
locations. A single discharge was collected at an appropriate transect location within at least one
single channel area to define boundary conditions and the remaining transects were surveyed
using a single pass with the ADCP to define the velocity profile.
The moderate flow survey was completed from August 18 to August 20, 2013 at flows ranging
between approximately 43,000 cfs and 60,000 cfs at the Susitna River at Sunshine gage
(provisional). The August 2013 field visit consisted of RTK GPS surveying of water level at
wetted edges for each transect, measuring flow at selected transects and classifying substrate for
each transect. Where possible, discharge was measured for each channel within each site at
locations that were wadeable to define model boundary conditions. Discharge was measured
using a handheld Sontek FlowTracker velocimeter with a top-set wading rod. Substrate was
visually assessed for each transect where visibility permitted and classified into dominant and
sub-dominant types using a modified Wentworth grain size scale. A percentage distribution was
estimated and assigned to the dominant substrate type. Where substrate composition could not
be determined visually, a long pole was dragged across the deep section of the transect to
identify general substrate category (boulder, cobble/gravel, fines).
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The low flow survey was completed from September 23 to September 25, 2013 at flows ranging
between approximately 25,000 cfs and 28,000 cfs at the Susitna River at Sunshine gage
(provisional). During the September 2013 visit, water levels and flow were measured as in the
August survey and substrate was reviewed and modified where better visual observations could
be made. Fish cover was inventoried for each transect and recorded as percent cover across
channel width and location on the cross-section for boulder, aquatic vegetation, overhanging
vegetation, undercut banks and woody debris.
4.6.1.3. Preliminary Model Development
4.6.1.3.1. 2-D Modeling
In 2013, data from the topographic ground surveys, ADCP bathymetric and velocity surveys,
LiDAR coverages, and substrate characterization surveys were QA/QC'd and transmitted to the
Geomorphology program to begin development of the 2-D hydraulic models. As part of the
Geomorphology Study (Study 6.6), two 2-D models are being considered including the Bureau
of Reclamation’s SRH2-D and the suite of River2D models (see ISR Study 6.6 for a description
of various 2-D model attributes and references). These two models have slightly different
capabilities relative to applications necessary for the Geomorphology program to model channel
bed evolution dynamics and are being evaluated accordingly. This evaluation will result in the
selection of a single 2-D hydraulic model to meet the needs of both the Geomorphology analysis
and the IFS Focus Area fish habitat analysis. Details of data QA/QC, 2-D model development
steps, and the comparative evaluation of the two models are provided in ISR Study 6.6.
Some preliminary, conceptual model results from the SRH-2D hydraulic model were presented
for FA-104 (Whiskers Slough) during the November 13-15, 2013, IFS-TT Riverine Modelers
Meeting (Tetra Tech 2013f).
4.6.1.3.2. 1-D Single Transect Modeling
In 2013, data from the ground surveys, LiDAR coverages, ADCP bathymetric and velocity
surveys, and substrate characterization surveys collected from the Lower River Segment
transects were QA/QCd and used in the initial development of the 1-D hydraulic models. This
involved the merging of electronic data sets from the RTK and ADCP surveys into a single
digital elevation model that could be used for generating cross-sectional profiles that extended
into the floodplain. Bathymetric and discharge field data were processed from the raw Sontek
RiverSurveyorLive data files that were collected during the ADCP field survey along with the
appropriate field notes from field crew. The RTK files were processed as described in ISR Study
8.5, Section 4.34 prior to merging with the ADCP files. The locations and elevations of the RTK
survey were treated as the reference points and the ADCP survey data were adjusted, as required,
to match the RTK data. The ADCP data were reviewed and processed as follows:
• Discharge transect pairs were identified using the field notes and geo-referenced data
location (transects originating at opposing start banks were selected);
• GPS position references were applied to discharge transect pair files (as opposed to
bottom track positional referencing);
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• The appropriate heading correction was applied to each file to account for any minor
compass bias introduced by ferrous material on the water craft or magnetic
declination inaccuracy (generally less that 10 degrees was applied), and
• A discharge summary for each transect pair was created.
There were some measured transects that did not have transects at opposing banks. In these
cases it was necessary to use transects that originated on the same bank. Discharges were
calculated and relevant summary sheets were produced for these locations .
The RTK system used to provide positional information to the RiverSurveyorLive program in
the field did not allow for a base position to be entered. This resulted in ADCP data points
collected to an accuracy of 0.06 ft (2 cm) to one another, but georeferenced to an accuracy of
approximately 3 ft–6 ft (1-2 m). To resolve this issue, calibrations were performed by the field
team to calculate offsets based on the accurately georeferenced RTK survey points
(approximately 0.06 ft) recorded at the same time and location by the RTK survey team. These
calculated offsets were then applied to the exported ADCP datasets. In cases where an RTK fix
was not achieved, the positional information collected loses accuracy, but the depth
measurements of the ADCP instrument remain accurate and suitable for developing cross-
sectional profiles. To resolve this, GIS was used to create a water surface based on the surveyed
RTK water level points. The depth parameter of the ADCP files was then used to calculate a
bottom elevation at each position. With this correction, the two horizontal components had an
accuracy of approximately 1 m ~ 2 m but the vertical component, the most important component
for one dimensional hydraulic modeling, had a survey instrument accuracy of approximately +/-
0.06 to 0.16 ft (3-5 cm). When boat movement and wave action was considered relative to the
assigned “flat” water surface elevation, the combined survey accuracy for the bottom topography
was approximately 0.33 ft (10 cm).
Water surface elevations for the Lower River Segment transects were simulated using the one-
dimensional HEC-RAS hydraulic model (Version 4.1, USACE 2010a, 2010b, 2010c). The
general steps used in the development of the HEC-RAS models included preparation of model
input data for the study reaches, calibrations of hydraulic models using available survey data
collected in June, August and September 2013, and sensitivity analysis of the hydraulic models.
The HEC-RAS hydraulic model was set up using the processed and merged field data files as
described above. The surveyed RTK and bathymetric data were combined with the SuWa
LiDAR topographic data to extend transects beyond the top of bank that was directly surveyed
during the RTK survey. These integrated survey data were used to generate the cross-section
profile at each river/creek station in the HEC-RAS hydraulic model. The same channel
geometric data created from the June 2013 survey were used for three model runs under high,
moderate and low flow conditions as represented by the June, August and September 2013 field
surveys, respectively.
The values of Manning’s roughness coefficient (n) were initially assumed and assigned to each
cross-section based on the observed dominant substrate materials in the channel as documented
during the field surveys. The initial estimated Manning’s n values ranged from 0.025 to 0.05
based on the published data for similar channel bed conditions (FHWA 1984 and Chow
1959). The estimated Manning’s n values were subsequently adjusted during the model
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calibration based on the surveyed flow and water level data. A sensitivity analysis was then
conducted by increasing and decreasing the Manning’s n values by 15% from the calibrated n
values to evaluate changes in water level relative to changes in roughness. The energy losses
associated with changes of channel cross-sections were accounted for during calibration by
assigning estimated expansion and contraction coefficients of 0.3 and 0.1, respectively.
The calibrated HEC-RAS models are being used to model cross-sectional depths and velocities
that will be used as input for PHABSIM modeling for the single transect locations in the Lower
River Segment.
4.6.2. Variances from Study Plan
AEA implemented the methods as described in the Study Plan pertaining to Middle River fish
habitat modeling with no variances. As described in the Study Plan schedule of activities, most
habitat modeling activities will occur after the ISR.
AEA implemented the methods as described in the Study Plan pertaining to Lower River fish
habitat modeling with the exception of the variance explained below:
• Two of the five sites identified for study in 2013 (R2 2013b) were not completed. Sheep
Creek and Caswell Creek within geomorphic reach LR-2 were deferred to the next study
year prior to the start of the 2013 field season. This approach will allow AEA to assess
the effectiveness of model outputs from the other three sites in the Lower River to assess
the need for additional fish habitat study sites in the next study year. Field studies have
been planned for the Sheep Creek and Caswell Creek sites as part of the next study year,
if required, as described in ISR Study 8.5, Section 7.6. The field execution plan and
schedule for 2013 was presented at an IFS Technical Team meeting on April 26, 2013
and progress updates on the field program were provided during each TWG meeting.
Delaying collection of field data to the next study year at Sheep Creek and Caswell Creek
is not anticipated to adversely impact achieving Project objectives.
4.7. Temporal and Spatial Habitat Analyses
AEA implemented the methods as described in the Study Plan with the exception of the variance
explained below (ISR Study 8.5, Section 4.7.2).
The IFS will result in the collection of data and the development of different types of habitat-
flow relationships from spatially distinct locations within each of the Focus Areas, and possibly
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: 1) those founded on PHABSIM
that depict WUA or habitat versus flow by species and life stage; 2) effective habitat-versus-
discharge relationships that define how spawning and incubation areas respond to flow changes;
3) varial zone analysis that quantifies areas of stranding and trapping relative to flow change; and
4) 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. Further, the IFS
will provide important information (e.g., 2-D hydraulic models and bathymetry data) that will be
used in the Fish Barriers (ISR Study 9.12) analysis relative to habitat connectivity. These
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relationships will be part of the analytical framework and conceptual models that will be used in
evaluating the operational effects of the Project (ISR Study 8.5, Section 4.8) on different
habitats. This evaluation will include 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 Susitna River. This latter analysis is needed in
order to assess system-wide Project effects.
4.7.1. Methodology
Completion of the temporal and spatial analyses is contingent on the acquisition and analysis of
data and subsequent development of models that will be used to assess both temporal and spatial
effects of Project operations. IFS-related data acquisition was initiated in Q2 2013 and will
continue during a next year of study; model development activities are ongoing and will be
completed during the next year of study prior to the USR. As a result, this ISR is limited
primarily to presenting potential methods and approaches for conducting the temporal and spatial
analyses. These were initially provided in the Study Plan, were discussed briefly during the
November 13-15 IFS TT Riverine Modelers Meeting and are presented in more detail in ISR
Study 8.5, Section 7.6. Further discussion with the TWG will occur in 2014 and will be
presented as part of the Proof of Concept presentations.
4.7.2. Variances from Study Plan
AEA implemented the methods as described in the Study Plan with the exception of the variance
explained below.
The final approach and details concerning the methods that will be used for conducting the
temporal analysis, including the time steps (hourly, daily, monthly, etc.), indicator parameters
(spawning period, incubation, substrate composition, water temperature, and other biologically
relevant indicators), and Project operational scenarios were scheduled to be worked out in
consultation with the TWG in Q4 2013, with the final approaches for both the temporal and
spatial analysis to be provided to the TWG in 2014 (see ISR Study 8.5, Section 7.9). Although
the general approaches to be used for the spatial analysis of the fish habitat models and the
temporal analysis for the different resource models were discussed as part of the November 13-
15, 2013 IFS TT Riverine Modelers Meeting, there was no specific TWG meeting in Q4 2013
that focused exclusively on those methods. Rather, the emphasis in Q4 2013 was on providing
the agencies and stakeholders with more information concerning each of the resource models and
how they would be used in addressing biological questions. However, AEA provides more
details concerning these methods in this ISR Study 8.5, Section 7.6 which will be demonstrated
during the Proof of Concept discussions in 2014. Thus, not having a specific meeting to discuss
spatial and temporal methods with the agencies in Q4 2013 will not affect the study objectives or
change the plans for completing the study.
4.8. Instream Flow Study Integration
AEA implemented the methods as described in this section of the Study Plan with no variances.
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The overall evaluation of Project effects on Susitna River resources will be accomplished via the
development of a suite of flow-sensitive resource specific models including those related to fish
habitat (Study 8.5), riparian ecology (Study 8.6), geomorphology (Study 6.5), water quality
(Study 5.6) groundwater (Study 7.5), and ice processes (Study 7.6), as well as numerous studies
focused on fish and fish habitats. These models are described in each of the respective ISR
sections just noted and were also discussed during the November 13-15 IFS TT Riverine
Modelers Meeting (AEA 2013). These models will be used both individually to address resource
specific questions as well as in an integrated fashion whereby outputs from various models serve
as inputs to other models that are designed to evaluate different biological questions. This
integration is described in the IFS Analytical Framework (ISR Study 8.5, Section 4.1) and
displayed in Figure 4.1-1. That figure also lists the Decision Support System (DSS) which will
consider Project effects resulting from different operational scenarios across a variety of resource
interests that go beyond fish habitat (e.g., wildlife, cultural, recreation, project economics, etc.).
AEA is in the process of developing a DSS to assist in the interpretation and evaluation of the
multitude of study results in preparation for evaluating Project effects. The DSS will aid in
interpretation by providing a consistent framework for each process, leading to an evaluation
metric. Evaluation metrics are also being developed for each resource area, which will provide
the basis for comparing alternatives for operational scenarios. The overall goal of the DSS is to
reduce the complexity of information and focus attention on trade-offs involved in the decision.
Progress during 2013 in development of the DSS was limited and is provided in ISR Study 8.5,
Section 5.8.
4.8.1. Methodology
Development of the DSS and completion of an integrated resource analysis is contingent on the
acquisition and analysis of data and subsequent development of resource specific models that
will be used to assess Project operations. Resource specific data acquisition was initiated in Q2
2013 and will continue during a next year of study; model development activities are ongoing
and will be completed during the next year of study prior to the USR. As a result, this ISR is
limited primarily to presenting potential methods and approaches for developing the DSS and
conducting the integrated resource analyses. These approaches were initially provided in the
Study Plan (RSP Section 8.5.4.8), and were discussed briefly during the November 13-15 IFS TT
Riverine Modelers Meeting. Further discussion with the TWG will occur in 2014 and will be
presented as part of the Proof of Concept.
4.8.2. Variances from Study Plan
AEA implemented the methods as described in this section of the Study Plan with no variances.
5. RESULTS
Field data that has been QA/QC’d, and initial model calibration information, are available on the
GINA website (http://gis.suhydro.org/reports/isr) and presented in this Results section and
Appendix D.
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5.1. IFS Analytical Framework
The analytical framework described in ISR Study 8.5, Section 4.1 and depicted in Figure 4.1-1
was introduced at the August 16, 2012, TWG meeting and further discussed at the October 24,
2012, TWG meeting. Essentially all of the IFS-related resource studies developed and
implemented in 2013 were structured to fit within the context of this framework and were
designed to address specific questions related to Project operations. This framework was
presented again and discussed in detail during the November 13-15, 2013, IFS-TT Riverine
Modelers Meeting where it served as the backdrop for all of the flow-specific resource models
discussed during the meeting. The framework also served to introduce the Decision Support
System that will be used for comparing operational scenarios across resource interests. The IFS
analytical framework will continue to serve as a means to demonstrate interrelationships between
riverine habitats and associated resource studies and models that will be used to address specific
questions.
5.2. River Stratification and Study Area Selection
5.2.1. Stratification
A hierarchical stratification system was developed for the Susitna River in 2013 that scaled from
relatively broad to more narrowly defined categories that included: Segment → Geomorphic
Reach → Macrohabitats → Mesohabitats (ISR Study 8.5, Section 4.2). This system differed
slightly from the original scale presented in the RSP, which included categories of Segment –
Geomorphic Reach – Mainstem Habitat Type – Main Channel Habitats and Off Channel
Habitats – Mesohabitat Types – Edge Habitat Types. The current designation simply collapsed
mainstem and off-channel habitats under Macrohabitats (which is consistent with the habitat
mapping studies (ISR Study 9.9) and removed Edge Habitats from the classification system as
recommended by FERC in the April 1 Study Plan Determination (see page B-208, FERC 2013b).
Specific details of the stratification approach are described in ISR Study 8.5, Section 4.2.
5.2.2. Study Area Selection
As noted in ISR Study 8.5, Section 4.2, the selection of study areas/study sites differed between
the Middle River Segment and Lower River Segment. Because Project operations are
anticipated to affect the Middle River Segment the greatest, the selection of study areas and
study sites within that segment received considerable attention and review with the TWG in
2013. The selection of study sites within the Lower River Segment was made subsequent to
completion and review of the Open-water Flow Routing Model (R2 et al. 2013) and other
hydrologic analyses that were presented and discussed during the February 14, 2013, TWG
meeting. The site-selection process for the Lower River Segment was less rigorous than for the
Middle River Segment and concentrated on selecting sites within visually determined
representative sections of the river as well as selected side channels, side sloughs, and tributary
mouths that were repeatedly used by fish as noted in the 1980s studies.
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5.2.3. Middle River Study Area/Site Selection
In the Middle River Segment, ten Focus Areas were identified, reviewed, and discussed with the
TWG and, with TWG input, finalized for detailed investigation in 2013. The distribution of
these Focus Areas included one in Geomorphic Reach MR-1, one in Geomorphic Reach MR-2 5,
one in Geomorphic Reach MR-5, four in Geomorphic Reach MR-6, two in Geomorphic Reach
MR-7 6, and one in Geomorphic Reach MR-8. Focus Areas were not selected for Geomorphic
Reaches MR-3 or MR-4 due to safety considerations related to Devils Canyon (Table 4.2-3).
Field studies were successfully conducted in 2013 at seven of the ten Focus Areas, with the
upper three areas not sampled due to access restrictions. The Focus Areas provide a common
geographic area within which multidisciplinary studies are being conducted. However, not all
Focus Areas were studied by all disciplines, depending upon the complexity and individual
characteristics of the Focus Area. For example, Groundwater (Study 7.5), Ice Processes (Study
7.6), and Riparian IFS (Study 8.6) studies were not conducted at all Focus Areas but were
limited to those areas in which these resource characteristics could be meaningfully influenced
by Project operations. In addition to the Focus Areas, 83 cross-sectional transects have been
established in the Middle River Segment in conjunction with development of the Open-water
Flow Routing Model. These transects will be evaluated for potential use in evaluating fish
habitat-related hydraulic characteristics.
5.2.3.1. Evaluation of Focus Areas
The Focus Areas were deemed representative of the major features within each geomorphic
reach and included mainstem habitat types of known biological significance (i.e., where fish
have been observed based on previous and/or contemporary studies), as well as some locations
(e.g., Slough 17) where previous sampling revealed few/no fish. The representativeness of the
Focus Areas was initially evaluated in 2013 using results of the aerial imagery-based habitat
mapping. Further analysis will be completed once results from the field habitat mapping
exercise are finalized (Study 9.9). The results of the initial analysis were presented in the March
1, 2013, Technical Memorandum (R2 2013b), discussed during the February 14, 2013, TWG
meeting and are briefly summarized below.
The initial habitat mapping of the Middle River Segment of the Susitna River was completed
using a combination of geo-rectified aerial imagery (Mat-Su Borough 2011) in combination with
high definition aerial videography taken of the river in August 2012 (flow conditions during the
videography were ≈ 10,000 cfs) (HDR 2013). The results of the habitat mapping provided a
spatial depiction of the distribution of habitat types and features throughout the entire length of
the Middle River Segment. Specific habitat types were digitized using ARC GIS and lineal
distances computed for each discrete habitat feature. Results of the habitat mapping were used to
evaluate the “representativeness” of the Focus Areas with respect to other areas of the river. In
this context, representativeness specifically refers to how well habitat units within the Focus
5 MR-2 originally contained two Focus Areas – FA-171 (Stephan Lake, Simple Channel) and FA-173 (Stephan Lake
Complex). Based on consultation with the TWG (R2 2013c), FA-171 (Stephan Lake, Simple Channel) was deleted
from MR-2.
6 MR-7 originally contained one Focus Area – FA-115 (Slough 6a). Based on consultation with the TWG (R2
2013c), a new Focus Area was established in MR-7 (FA-113 [Oxbow 1]).
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Areas represent habitat units outside of these areas within the same geomorphic reach. For this
initial evaluation, representativeness was examined by 1) comparing the representation of habitat
types within the Focus Areas to the representation of habitat types in the entire geomorphic
reach; 2) determining if the habitat types have been proportionately represented (Focus Area vs.
non-focus areas); 3) determining if there was a bias in the habitat types that were selected in the
Focus Areas; and 4) evaluating whether a random systematic approach in the selection of Focus
Areas would yield results different from the selection process and criteria applied to the current
Focus Areas.
5.2.3.1.1. Evaluation of Representativeness – Representation and Proportionality
Because the length of river that is included in the Focus Areas is less than that not included in the
areas, some scaling of counts and lengths of the habitat types was necessary for proportional
comparisons. For this, a suite of scaled metrics was developed and used in a comparative
analysis of the representativeness of habitat types within and outside of Focus Areas. These
metrics included the major habitat categories specified in the classification, and consisted of
percentages or proportions of lineal distances, and of densities (length per mile) (Table 5.2-1).
Values for these metrics were compared graphically by geomorphic reach to determine whether
1) each habitat type contained in the geomorphic reach was represented in the Focus Areas
within the reach; and 2) the representation was proportional. The metrics could not be
statistically compared within geomorphic reaches (focus area vs. non-focus area) because they
do not represent multiple independent random samples. Thus, there was no estimation of
variance determined.
Main channel proportionality metrics are displayed graphically in Figure 5.2-1. Geomorphic
Reach MR-1 was all single main channel, while Geomorphic reaches MR-2, MR-5, and MR-6
contained small amounts of split main channel, which was not represented within the Focus
Area. In Geomorphic Reach MR-7, the split main channel was represented, but at a higher
proportion than exists in the full reach. In Geomorphic Reach MR-8, the braided main channel
was not represented in the Focus Area, and the split main channel was represented at a lesser
proportion in the Focus Area.
Side channel and slough proportionality metrics are displayed graphically in Figure 5.2-2. Side
channels were represented in Geomorphic Reach MR-1. In Geomorphic Reach MR-2, Focus
Areas exhibited all habitats, with a higher proportion of side sloughs than were contained in the
full reach. The small amounts of side slough habitat in Geomorphic Reaches MR-5 and MR-7
were not represented in Focus Areas. Geomorphic Reach MR-6 was well represented by side
channels and side sloughs present in Focus Areas. Geomorphic Reach MR-7 side channels and
upland sloughs were likewise represented in Focus Areas within that reach. In Geomorphic
Reach MR-8, all habitats were represented in the Focus Areas, but there was proportionately
more side channel and side slough habitat than in the reach at large. Additional results for
beaver complex, backwater, and tributary categories are presented in R2 2013b.
Overall, the results of the analysis indicated that the Focus Areas captured the majority of habitat
types present in each Geomorphic Reach.
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5.2.3.1.2. Evaluation of Representativeness – Bias
Bias in the method in which Focus Areas were selected was examined by considering the
geomorphic reaches as independent replicates of potential bias, and testing if the average bias is
different from zero using a t-test or a non-parametric equivalent. For example, if the Focus
Areas selection consistently under-represented upland sloughs, the analysis would highlight that
result.
Results of the bias estimates are displayed in Table 5.2-2. A negative number indicates that a
habitat was over-represented in the Focus Areas, and a positive number indicates that a habitat
was under-represented. Because there is a fairly even distribution of cases where habitat was
under-represented and over-represented across reaches, there was no strong evidence (i.e., no
statistically significant results at an alpha level of 0.10) of bias in the habitat types that were
selected within the Focus Areas.
5.2.3.1.3. Evaluation of Representativeness – Random/Systematic Approach
As a fourth evaluation of representativeness, a set of simulated random Focus Areas was selected
based on a random systematic sampling approach. These areas were selected from each
geomorphic reach, matching the number and total coverage of focus areas for each geomorphic
reach. For example, in Geomorphic Reach MR-2, there are two Focus Areas with a total length
equal to 3.2 miles. For simplicity, the simulation selected two equally sized focus areas, also
totaling 3.2 miles. The process in Geomorphic Reach MR-2 began with a random start and the
formation of eight contiguous 1.6-mile reaches. Then one of the four paired equally spaced
reaches [(1,5), (2,6), (3,7), (4,8)] was selected at random. A similar process was applied to the
remaining five geomorphic reaches. Both the current Focus Area location(s) as well as the
randomly selected counterparts are displayed in Table 5.2-3. The habitat features of this
simulated set of focus areas was then evaluated in the same manner as the current Focus Areas,
and comparisons were made.
The simulated selection of a set of random systematic Focus Areas resulted in a different balance
of habitat units. For some habitat types in some geomorphic reaches, the random Focus Areas
appear to be more representative. For example, the main channel types (main, split, braided) in
Geomorphic Reach MR-8 were proportionally similar in the random Focus Areas and in the
reach as a whole. However, in some areas the random Focus Areas miss the same habitat types,
as for off-channel habitats in Geomorphic Reach MR-5. In other areas, the random Focus Areas
are less representative, as in off-channel habitats in Geomorphic Reach MR-8.
Bias estimates for random Focus Areas are displayed in Table 5.2-4. A negative number in this
table indicates that a habitat was over-represented in the random Focus Areas, and a positive
number indicates that a habitat was under-represented. These results show that the random
Focus Areas consistently over-represented side channels and consistently under-represented
riffles (with alpha = 0.10). This analysis again indicated that although the selected Focus Areas
do not perfectly represent every habitat in every geomorphic reach, the results are similar to what
would be expected with a random systematic sampling scheme.
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5.2.3.1.4. Selection of Final Focus Areas
Overall, the results of the habitat mapping and statistical analysis completed in 2013 indicated
that the ten Focus Areas selected in the Study Plan are generally representative of habitat types
found in other portions of the river. As a result, those ten Focus Areas were selected for study in
accordance with the respective resource-specific study plans.
A caveat to the above is that the analysis did show that some habitat types within individual
geomorphic reaches were not represented in the reach-specific Focus Areas or captured in the
existing transects. The Study Plan described several considerations that were made relative to
adding supplemental sites in 2013. No adjustments were made in 2013, but this will be
evaluated further once results of the habitat characterization analysis are completed (ISR Study
9.9).
5.2.4. Lower River Study Area/Study Site Selection
In the Lower River Segment, study sites were selected in Geomorphic Reaches LR-1 and LR-2
based on a combination of representative and critical study sites. Instream flow sites were
limited to these upper two geomorphic reaches since Project effects become more attenuated
downstream (as demonstrated by results of open-water hydraulic flow model). One area was
selected in each of the two geomorphic reaches, with the area in Geomorphic Reach LR-1
located around Trapper Creek near PRM 95.4 (Figure 4.2-11) and the area in Geomorphic Reach
LR-2 located around Caswell Creek near PRM 67.3 (Figure 4.2-12).
5.3. Hydrologic Data Analysis
5.3.1. Mainstem Susitna River
Results from the stage and discharge surveys are summarized in Table 5.3-1 and locations are
provided in Figure 5.3-1. The table includes data collected in both 2012 and 2013 and indicates
for each cross-section measured, whether or not a bathymetry profile was collected, the date of
the measurement, and the corresponding discharge and water surface elevation. In many cases,
only a water surface elevation was collected in which case blank values occur under the
discharge heading. Each discharge measurement has an associated rating of poor, fair, good, or
excellent (see ISR Study 8.5, Appendix C for more detail). Of the 184 discharge measurements,
1 was rated as poor, 8 as fair, 77 as good, and 98 as excellent. A technical memorandum, dated
December 2013 and prepared by Brailey Hydrologic, provides a more detailed description of the
ADCP boat measurement data collection, and the QA/QC process that was applied to the data
including the calculation of uncertainty (ISR Study 8.5, Appendix C). AEA is aware of a
velocity profile QA/QC processing issue documented by the newly released USGS Office of
Surface Water Technical Memo 2014.02 (USGS 2013) and discussions are ongoing as to
whether some modification of the flow data is warranted. At this time, some minor changes
resulting in an approximately 1 to 6 percent increase in flow values are anticipated.
There were ten discharge measurements in the lower river (located at PRMs 94.8, 90.2, 78, 73.1,
67.2, 54.2, 49, 40.4, 36.4, and 34.8) that were based on multiple channel measurements In these
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cases, the discharge rating methodology was correspondingly modified as described in ISR
Study 8.5, Appendix C.
Two high-flow events occurred during data collection efforts, one on September 21, 2012, with a
peak flow of 72,900 cfs at Gage No. 15292000 at Gold Creek, and the other on June 2, 2013,
with a peak flow of approximately 90,700 cfs (based on provisional USGS data for Gage No.
15292000 at Gold Creek). Because high flows can move and transport sediments and modify
channel form, a second set of bathymetry data was collected at 14 cross-sections in 2012 after
the September 21, 2012 flood event. This enabled a comparison of channel cross-sectional
profiles pre- and post-flood (Figure 5.3-2 and Figure 5.3-3).
Full bathymetry datasets were not collected again in 2013 and therefore it was not possible to
complete a similar pre-post comparison after the June 2, 2013 flood. However, discharge data
were collected at six sites in 2013 that were at or proximal to sites that had been surveyed in
2012. Because the ADCP acquires a channel profile as part of a discharge measurement, those
profiles can be used for making pre-post June 2, 2013 channel conditions. At each of the six
cross-sections, four ADCP passes were made resulting in four profiles for each cross-section.
For comparative purposes, these profiles are graphically displayed along with profiles obtained
for both pre-, and for five of the cross-sections, post-2012 flood conditions (Figure 5.3-4).
Stage recording measurements collected at the 13 ESS sites in the mainstem of the Susitna River
are displayed in Figure 5.3-5 and Figure 5.3-6, Finalized data were only available through
October 31, 2012. Once available data have been finalized, figures will be updated similar to
that provided in Figure 5.3-7 for station ESS20.
Winter discharge measurements were also collected on the mainstem of the Susitna River. The
results of this data collection effort are provided in Ice Processes, Section 7.6.
Flow measurements associated with the development of 2-D-hydraulic models were collected in
seven Focus Areas within the Middle River Segment. These included measurements in FA-104
(Whiskers Slough), FA-113 (Oxbow 1), FA-115 (Slough 6A), FA-128 (Slough 8A), FA- 138
(Gold Creek), FA-141 (Indian River) and FA-144 (Slough 21). Measurement locations were
selected to quantify flow splits among various channels and sloughs, resulting in 10 to 14
measurements per Focus Area. Moving bed tests were performed at representative main channel
locations, with each measurement consisting of at least two reciprocal tests. The uncertainty of
2D-model flow measurements was evaluated using streamwise summations of riverwide flow. A
final summary of the Focus Area measurements is provided in Table 5.3-2. This table includes a
section for each of the seven Focus Areas measured with data organized by transect and date.
Each measurement includes the portion of the channel measured in each transect and the total
flow. More detailed data processing and results such as the compass calibration, loop test,
measurement duration, mean velocity, extrapolation settings, percent top, bottom, and edge
estimates, and the coefficient of variation can be found in ISR Study 8.5, Appendix C.
5.3.2. Tributaries to Susitna River
Site schematics are provided in ISR 8.5, Appendix E for all continuous tributary gaging sites.
These schematics include the location of the benchmarks, transect profile, staff gage, and water
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level recorder. Representative site photographs are provided in ISR Study 8.5, Appendix F.
Streamflow and staff gage measurements for the data collected in 2013 are provided in Table
5.3-3. The 15-minute streamflow data are provisional and not provided in the ISR. These data
will be provided once additional data are collected and rating curves updated.
5.3.3. Realtime Hydrologic Data and Network
A summary of the types of data collected at the 13 surface water stations in the realtime
hydrologic data network is provided in Table 4.4-2. This table includes the location of each
station (PRM), the periods of monitoring various parameters (water level, water temperature, and
air temperature), and whether camera images were collected. A map of these stations is provided
in Figure 4.4-1.
5.3.4. Representative Years
Project effects will need to be evaluated over a range of climatic and hydrologic conditions
which requires the selection of representative year types from the hydrologic record. An initial
evaluation of representative years was completed in 2013 and was based on defining wet,
average, and dry conditions during periods of warm or cool PDO phases. AEA’s Fluvial
Geomorphology Studies (ISR Study 6.6) provided an initial evaluation of representative years
that identified a 50-year period of record from the 61 years included in the Streamflow Record
Extension Study (USGS 2012). From this record, candidate years were identified for
representative wet, average, and dry conditions during periods of warm or cool PDO. The
methods and results of this analysis can be found in ISR Study 6.6, Appendix: Evaluation of 50-
Year Simulation Period, Pacific Decadal Oscillation, and Selection of Representative Annual
Hydrographs. This analysis compared years using a rank of both annual and monthly average
flow volumes. The PDO analysis revealed no identifiable influence of warm or cool PDO
periods on wet, average, and dry conditions, except during the winter. Higher winter flows were
associated with warm PDO and lower winter flows were associated with cool PDO. Ultimately,
four years were evaluated for each of the wet, average, and dry conditions (12 total) (Figure 5.3-
8) and from this total, three years were preliminarily recommended. Year 1981 was
recommended to represent wet conditions, 1985 to represent average conditions, and 1950 to
represent dry conditions.
AEA completed additional analysis of the open-water period (May to September) from a habitat
modeling perspective. For this, an average monthly and range in average monthly flow from
May through September were evaluated. The average monthly flow was calculated from the
same 50-year period of record. First, each month from May through September was ranked
using the monthly flow for all 50 years.The lowest and highest ranks for the 5-month period
were then identified and used to calculate an average for that period. This average was then used
to rank the 50 years again, andthe difference in the highest and lowest rank for that 5-month
period calculated. The 5-month average rank and 5-month difference in rank were then used to
review the 50 years. A wet year was identified as one with a low average and a low difference
between ranks. A dry year was identified as one with a high average and a low difference
between ranks. An average year was identified as one with a medium average and low
difference between ranks.
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The monthly hydrographs of the four potential years for each of the wet, average, and dry
conditions identified in ISR Study 6.6 are shown on a linear scale in Figure 5.3-8 and on a
logarithmic scale in Figure 5.3-9. The linear scale can be used to compare the summertime flows
while the logarithmic scale can be used to compare the wintertime flows. Additional input on
representative years was also provided from the ice processes studies, which involved
consideration of the temperature conditions of the winter period, rate and extent of freeze-up, and
amount of snow cover.
Overall, AEA’s analysis resulted in the selection of three candidate years to represent wet,
average and dry conditions consisting of 1981, 1985,and 1970, respectively. The year selected to
represent the dry year, 1970 was different than the one originally selected by the geomorphology
analysis, 1950. This change to 1970 was based on input from fish habitat and ice processes
considerations and was selected since it had a lower wintertime flow as shown in the bottom plot
of Figure 5.3-9.
These three candidate years will be presented to the agencies and discussed with the TWG in
2014. Once finalized, the hydrology associated with the three representative years will be used
in multiple resource modeling efforts. Both the Reservoir Operations Model and the Open-water
Flow Routing Model will have the ability to simulate the 61-year period of record, but these
representative years may be used first to evaluate and consider specific operational conditions.
Both the ice-processes flow routing and the sediment transport 1-D modeling will have the
ability to simulate the abridged 50-year period of record. These three representative years may
also be used for initial simulations to evaluate Project operations.
Additional years may be selected for the ice processes modeling to represent specific severe
breakup ice jamming years; the candidate representative wet, average, and dry years do not
include incidence of breakup ice jamming.
5.3.5. Indicators of Hydrologic Alteration and Environmental Flow Components
As noted in ISR Study 8.5, Section 4.4, AEA’s application of the IHA models in 2013 were
limited to the hydrology of the Stikine and Taku rivers as part of the Biological Cues Analysis
described in ISR Study 8.5, Section 4.5. AEA has developed a proposed IHA approach for
analysis of Susitna River hydrology data. The approach will be discussed with the TWGand
completed during the next year of study.
5.4. Reservoir Operations and Open-water Flow Routing Modeling
5.4.1. Reservoir Operations Model
Input in terms of daily inflows to the Reservoir Operations Model was based on the USGS
Susitna River watershed record extension study (Curran 2012). The 61 years of monthly average
flows at Gold Creek are shown on Table 5.4-1, with a similar table for the calculated monthly
inflows to Watana Reservoir presented in Table 5.4-2.
The output of the Reservoir Operations Model can be used to provide an indication of
powerhouse discharge variability. This output serves as input into the Open-water Flow Routing
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Model that can be used to predict stage and flow conditions resulting from a given powerhouse
discharge at locations downstream (ISR Study 8.5, Section 5.4.2). For efficient operation of the
whole interconnected Railbelt system, powerhouse discharges are expected to normally vary
over a 24-hour period to serve the electricity load variability in the Railbelt region. However, it
is difficult to characterize typical powerhouse operations before production modeling simulation
of the Railbelt is complete. Nevertheless, AEA completed a simulation model run that assumed
that the generation requirements for the Project for the year included the entire seasonal, weekly,
daily, and hourly load fluctuations of the entire Railbelt; Railbelt electricity loads for this
scenario were taken from the 2010 Railbelt Regional Integrated Resource Plan (RIRP). This run
was termed the Maximum Load Following Operational Scenario-1 (OS-1). This scenario was
presented for illustration purposes at two TWG meetings, the first on October 24, 2011 (MWH
2011) and the second on October 23-25, 2012 (MWH 2012). As noted, OS-1 represents an
extreme condition that would rarely if ever occur since AEA would also rely on other projects
(e.g., Bradley Lake) to meet load fluctuations.
For illustration purposes, minimum instream flows were included at Gold Creek as part of the
Maximum Load Following OS-1 operating plan; these flows were those specified under Case E-
VI from the 1985 FERC License Application (FERC No. 7114). Those criteria specified a
minimum wintertime flow of 2,000 cfs at Gold Creek, increasing to a minimum flow of as much
as 9,000 cfs from June 3 through September 1. However, for planning purposes, AEA adjusted
the 2,000 cfs minimum winter flows to 3,000 cfs at Gold Creek. The relevant results from the
Reservoir Operations Model for the IFS are the total reservoir outflows. For OS-1, these results
are plotted in Figure 5.4-1.
5.4.2. Open-water Flow Routing Model
This section provides the results of the field data collection in 2012, the calibration and
validation steps used for Version 1 of the Open-water Flow Routing Model, and results of some
preliminary model runs based on the Maximum Load Following scenario, OS-1 described above.
A complete description of the development of Version 1 of the model is provided in R2 et al.
(2013).
5.4.2.1. Field Data Collection
Version 1 of the Open-water Flow Routing Model relied on field data that were collected in
2012. These data included:
• Cross-sections of the Susitna River surveyed between PRM 80.0 and PRM 187.2
• Flow measurements and concurrent water surface elevation surveys at the river cross-
sections as described in ISR Study 8.5, Section 4.4 and ISR Study 8.5, Appendix A and
C.
• Stage hydrographs measured at gaging stations established on the Susitna River
Additional field data were collected in 2013; data collection methods are described in ISR Study
8.5, Section 4.4, Hydrologic Data Analysis. A summary of the cross-sectional profile data
collected in 2012 and 2013 is provided in Table 5.3-1. This table summarizes the cross-section
location, date of data collection, and the associated water surface elevations or discharge
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measurements. The location of the 2012 and 2013 cross-sections are shown in Figure 5.3-1, and
examples of two of the river cross-sections (PRM 173.1 and PRM 80) shown in Figure 5.4-2. At
PRM 173.1 (between the proposed dam site and Devils Canyon), the channel had a single thread
width of about 600 feet. At PRM 80 (downstream from the Three Rivers Confluence), the
channel was multi-threaded with a total width of about 1 mile. An example of the output from
one of the June 21, 2012 passes at PRM 173.1 is shown in Figure 5.4-3.
5.4.2.2. Model Development and Calibration
Version 1 of the Open-water Flow Routing Model was developed from the 88 cross-sections
surveyed in 2012 For numerical stability under unsteady conditions, additional river cross-
sections were interpolated at 1,000-foot intervals. This was necessary to route flows through
Devils Canyon, a 14-mile-long reach of the Susitna River where for safety reasons no cross-
sections were surveyed. With the interpolated cross-sections added to the model, the average
drop in elevation between cross-sections was about 2 feet. A longitudinal thalweg profile of the
Susitna River was then developed from the 88 cross-sections (Figure 5.4-4). The channel
gradient was steepest through Devils Canyon (0.52 percent) with a gradual reduction in channel
gradient downstream.
5.4.2.2.1. Steady State Model
The Open-water Flow Routing Model was first calibrated under steady-state conditions using
170 pairs of flow/water surface elevation measurements obtained at the 88 cross-sections in
2012. The relative magnitude of these flow measurements was assessed by using the concurrent
flows in the Susitna River at Gold Creek (USGS Gage No. 15292000) as a common reference
point (Figure 5.4-5). This calibration provided for the calculation of water surface elevations to
within plus or minus 0.2 feet of the observed water surface elevation. The model was calibrated
by selecting a reasonable Manning’s “n” based on records of field observations and photographs,
and by adjusting the shape of the interpolated cross-section located downstream from each
surveyed cross-section. A summary of the Manning’s “n” coefficients that were used for model
calibration is presented in Figure 5.4-6. The Manning’s “n” coefficients ranged from 0.030 to
0.045. Unsteady State Model.
Flow hydrographs measured in 2012 by the USGS were used to calibrate the flow routing model
under unsteady-state conditions. Hydrology data for the week of August 11 to 17, 2012, were
selected for model calibration. This week was selected because it demonstrated a distinct pattern
of diurnal flow pulses associated with glacial melt (Figure 5.4-7 and Figure 5.4-8). By
examining the 15-minute flow hydrographs in the Susitna River above Tsusena Creek and at
Gold Creek, it was found that the two hydrographs could be synchronized if the flow hydrograph
in the Susitna River above Tsusena Creek was shifted forward by 6.4 hours (Figure 5.4-9). The
travel time of the pulses over the 47.2-mile-long distance between the two gages is therefore 6.4
hours. The speed of propagation of the pulses, also referred to as the celerity, was estimated to
be 7.4 miles per hour (mph) (10.8 feet per second (fps)). The difference in magnitude of flows
from Figure 5.4-9 was used to estimate a hydrograph of the ungaged lateral inflow to the Susitna
River between Tsusena Creek and Gold Creek. A similar process was used to estimate
hydrographs of ungaged lateral inflow to the Susitna River between Gold Creek and Sunshine.
However, the process, which is more fully described in R2 et al. (2013) was complicated by the
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diurnal fluctuations observed in the Susitna River at Sunshine which were influenced by the
fluctuations observed in the Susitna River at Gold Creek, the Chulitna River, and the Talkeetna
River. The resultant flow hydrographs for the ungaged lateral inflow to the Susitna River are
shown in Figure 5.4-10.
The goal of calibration under unsteady-state conditions was to match the arrival time of pulses
from upstream sources in the Susitna River at Gold Creek and also at Sunshine. If it was
necessary to accelerate the arrival time of pulses from upstream sources, then interpolated cross-
sections that were not used for steady-state calibration were made narrower to increase the
celerity. If it was necessary to decelerate the arrival time of pulses from upstream sources, then
interpolated cross-sections that were not used for steady-state calibration were made wider to
decrease the celerity. Initial analysis of the data predicted that the diurnal pulses would arrive
late in the Susitna River at Gold Creek (USGS Gage No. 15292000). To accelerate the arrival of
the pulses, the interpolated cross-sections in Devils Canyon were made narrower. After this
adjustment, there was good agreement between measured and simulated hydrographs in the
Susitna River at Gold Creek (Figure 5.4-11).
Finally, the celerity that was derived from the August 2012 diurnal pulses in the Susitna River
between the proposed Watana Dam site and the Gold Creek gage (USGS Gage No. 15292000)
was used to help select a computational time step in the Open-water Flow Routing Model. For
numerical stability and accurate results, the computational time step should be less than the
distance between river cross-sections divided by the celerity. With the surveyed and interpolated
cross-sections combined, the distance between cross-sections is about 1,000 feet. This distance
divided by the celerity (10.8 fps) yields a time increment of 93 seconds. Thus, a computational
time step of one minute (60 seconds) was adopted for the Open-water Flow Routing Model.
5.4.2.3. Model Validation
The Open-water Flow Routing Model, that was calibrated under both steady and unsteady- state
conditions, was then validated using the available hydrologic dataset for the June 4 through
October 14, 2012, period. Input to the model was based on the flow hydrographs illustrated in
Figure 5.4-12, Figure 5.4-13, and Figure 5.4-14. Validation consisted of comparing simulated
versus measured hydrographs in the Susitna River at Gold Creek and Sunshine. A comparison of
measured and simulated hydrographs for this validation period is shown in Figure 5.4-15 for the
Susitna River at Gold Creek (USGS Gage No. 15292000) and in Figure 5.4-16 for the Susitna
River at Sunshine (USGS Gage No. 15292780). Good agreement was found between measured
and simulated hydrographs at both locations over a wide range of flow conditions.
5.4.2.4. Preliminary Model Runs – OS-1
Potential downstream changes in flow and water surface elevations were assessed by comparing
Pre-Project conditions with a Maximum Load Following Operational Scenario 1 (OS-1)
conditions for calendar year 1984. Calendar year 1984 was selected because historical gage
records were available from the USGS, and because 1984 represents an average hydrological
condition on both an annual and monthly basis.
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The two scenarios (i.e., Pre-Project and OS-1) represent different flow hydrograph releases from
the proposed Watana Dam and were used as input to the Open-water Flow Routing Model
(Figure 5.4-1). Under Maximum Load Following OS-1, higher flows would generally be
released during winter, and lower flows would be released during the spring and summer until
the reservoir fills to capacity. During periods when the reservoir is not full, flow releases under
the Maximum Load Following OS-1 would exhibit daily and weekly flow fluctuations in
response to power generation requirements.
Daily flow records for 1984 were available from the USGS for the following locations:
• Susitna River above Tsusena Creek, USGS Gage No. 15291700
• Susitna River at Gold Creek, USGS Gage No. 15292000
• Chulitna River near Talkeetna, USGS Gage No. 15292400
• Talkeetna River near Talkeetna, USGS Gage No. 15292700
• Susitna River at Sunshine, USGS Gage No. 15292780
These daily flows were converted to 15-minute flows in a manner as illustrated in Figure 5.4-17.
With the 15-minute flow hydrograph, the daily average was preserved each day and the
hydrograph was smooth and continuous. No attempt was made during these Version 1 Open-
water Flow Routing Model runs to account for diurnal glacial melt fluctuations. The 15-minute
flow hydrographs, thus derived, are illustrated in Figure 5.4-18, Figure 5.4-19, and Figure 5.4-
20.
The calibrated model was then used to assess downstream stage changes associated with Pre-
Project and Maximum Load Following OS-1 scenarios for calendar year 1984. The analysis
considered changes in stage and flow at locations just below the Watana Dam Site, at Gold
Creek, and at Sunshine. Analyses were completed and results graphically displayed at each of
these locations for three time periods; the entire year, a summer period consisting of the week of
July 23 to July 29, 2012, and a winter period consisting of the week of January 8 to January 14,
2012. Summer and winter analysis were also completed at a river location at PRM 87.1 just
downstream of Sunshine that was deemed more representative of channel characteristics than at
the Sunshine gage site. The detailed results of these analysis including figures that compare
predicted flows and stage changes for Pre-Project and OS-1 conditions are provided in R2 et al.
(2013) (see Section 5 and Figures 5.4-1 through 5.4-21 of R2 et al. 2013). Two of these figures
depicting stage changes for the July 23 to July 29. 2012 period for Gold Creek and Sunshine are
reproduced here as Figure 5.4-21 and Figure 5.4-22, respectively. During the summer, hourly
stage fluctuations within each day were predicted to range from 0.7 to 1.0 feet at Gold Creek and
from 0.2 to 0.4 feet at Sunshine. As noted above, the OS-1 Scenario represents an extreme
condition that was for illustration purposes only and does not reflect how AEA would normally
operate the Project.
5.5. Habitat Suitability Criteria Development
This section provides information on the preliminary results of the HSC/HSI studies conducted
during 2013. Data collection efforts represent those completed through late September 2013,
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while the. analysis of the information presented continued into mid-December 2013. Much of
the data analysis required for this study has not progressed beyond the development and
refinement of analytical methods that will be performed in 2014. Additionally, draft periodicity
tables (ISR Study 8.5, Appendix H) and results of the Biological Cues Study (ISR Study 8.5,
Appendix B) have been developed.
Major activities completed in 2013 included: 1) selection of target species and life stages; 2)
development of draft HSC/HSI curves using existing information; 3) selection of HSC/HSI
sampling locations; 4) collection of microhabitat use data for the target fish species; 5) collection
of habitat availability data; 6) development of HSC/HSI histograms displaying frequency of use
for different microhabitat variables; 7) preliminary development of microhabitat preference
curves; 8) completion of pilot winter use studies; 9) collection of microhabitat data as part of
River Productivity studies; 10) development of draft periodicity tables; and 11) completion of the
biological cues analysis. The following sections present results of each of these activities.
5.5.1. Selection of Target Species and Life Stages
In collaboration with the TWG, AEA identified 19 fish species for potential development of site-
specific HSC curves (Table 4.5-2). The list of species was further refined by ranking or
prioritizing the list into high, moderate, or low categories of potential curve development. High-
ranked species included the five Pacific salmon species, Arctic grayling, and rainbow trout. The
list of moderate-priority species included burbot, Dolly Varden, eulachon, humpback whitefish,
and longnose sucker. The high and moderately ranked species are generally considered the most
sensitive to habitat loss through manipulation of flows in the Susitna River. For low-priority
species, it is anticipated that insufficient observations will be collected to develop site-specific
HSC curves and therefore they will be grouped or guilded with other species for which curves
can be developed.
5.5.2. Development of Draft HSC Curves Using Existing Information
A summary description of the data sources and HSC curve developed for each individual species
as part of the 1980s Su-Hydro instream flow studies is presented below. Additionally, a brief
description of other relevant HSC curve sets reviewed as part of this effort is provided.
Additional details and plots of each of the curve sets discussed below are presented in the 2012
Compendium of Technical Memoranda (R2 2013e) and are not repeated here.
5.5.2.1. 1980s Susitna River HSC Curves
An extensive set of HSC curves was 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 professional
judgment of project biologists. Microhabitat data were collected for various species and life
stages of fish, and are 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. 1984a). Data
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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. 1984b). 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. 1984a).
These HSC were developed based on field data collected at representative tributary, slough, and
side channel sites between Three Rivers 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 (e.g., 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 Three Rivers 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. 1984b). 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.
5.5.2.2. Other Relevant HSC Curve Sets
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). 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. Depth and velocity data were collected for pink and chum
salmon spawning and HSC curves developed HSC curves for Chinook and coho spawning,
incubation, fry, and juveniles were based solely on pre-existing depth and velocity curves.
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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” was developed all three habitat parameters.
More recently, PLP (2011) 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
information and curve sets from other studies, as well as through collecting and analyzing site-
specific data for various target species and life stages. HSC curves developed 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).
5.5.3. HSC/HSI Study Area Selection
The selection of 2013 HSC/HSI sampling sites relied on a stratified random sampling approach
based on macrohabitat composition within each Focus Area, as well as known fish use. The
selection process also considered access restrictions. This resulted in selection of 68 individual
habitat segments representing 10 different habitat types within the 7 Focus Areas: (FA-104
(Whiskers Slough), FA-113 (Oxbow 10, FA-115 (Slough 6A), FA-128 (Slough 8A), FA-138
(Gold Creek), FA-141 (Indian River) and FA-144 (Slough 21) (Table 4.5-4). Of the 10 habitat
types selected for sampling, side channel habitat had the most (17) segments selected. The
distribution of sampling sites between Focus Areas was generally equal with an average of 10
sampling reaches selected within each. Additional sampling sites were added from areas outside
of the Focus Areas to ensure that highly utilized fish habitats (known spawning locations or areas
identified by other study teams) were included in the sampling. Each of the selected habitat
segments was sampled a minimum of two times and in some cases three times, resulting in a
total of 210 unique sampling events (including both 50- and 100-meter sampling sites). The
location of each sampling event within each of the 7 Focus Areas is presented in Figure 5.5-1
through Figure 5.5-7.
5.5.4. Collect Site-Specific Habitat Suitability Information
The following sections summarize the results of HSC data collection efforts and the resulting
development of HSC histograms from the 2013 data collection effort. Results are organized and
reported by species.
Habitat suitability sampling occurred over a variety of river flows during the summer of 2013
ranging from approximately 10,500 cfs to just over 45,000 cfs as measured at the Gold Creek
gage (Figure 5.5-8). Habitat measurements were collected for four different life history stages
(spawning, juvenile, fry, and adult) and twelve different fish species: Chinook, sockeye, chum,
coho, and pink salmon; rainbow trout; Arctic grayling; Arctic lamprey; Dolly Varden char;
whitefish; longnose sucker; and burbot. A total of 1,433 observations of site-specific habitat use
was recorded during the 2013 HSC/HSI surveys of the Middle River Segment of the Susitna
River (Table 5.5-1). As previously described, microhabitat observations were concentrated in
randomly selected habitat types within 7 of the 10 Focus Areas. Data collection was completed
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during seven sampling sessions (June 18-22, July 10-17, July 23-30, August 6-13, August 20-26,
September 10-17, and September 24-29) from mid-June through late-September 2013. The
numbers of sampling events by sample session, Focus Area, and habitat type are presented in
Table 5.5-2.
Spawning activities were first observed during HSC/HSI surveys in early August and extended
until late September. Spawning activity in the seven Focus Areas was only observed for pink,
chum, sockeye, and coho salmon. Approximately half (49 percent) of the 591 spawning HSC
measurements were completed during the September 9-18 sampling session. Just over 70
percent of all spawning observations were recorded in side channel and side slough habitats.
HSC/HSI surveys for the adult, juvenile, and fry life stages were completed within each of the
seven sampled Focus Areas with a total of 851 habitat use measurements. Similar to the
spawning life stage, just over 70 percent of all HSC observations for adult, juvenile, and fry life
stages were collected from side channel, side slough, and upland slough habitat types. A
summary of results for the 2013 HSC data collection is presented below for each of the twelve
species mentioned above. Histogram plots are presented in ISR 8.5, Appendix G and describe
the relative frequency in which individual species and life stages utilized depth, velocity, and
substrate microhabitats.
5.5.4.1. Chinook Salmon
During the 2013 HSC surveys, no Chinook salmon were observed spawning in the mainstem
Susitna River (Table 5.5-1). Although radio telemetry surveys conducted by LGL in 2012 and
2013 routinely found adult Chinook holding in the mainstem Susitna River, only one location at
the mouth of Indian River was identified as a potential spawning location in the Middle River
Segment of the Susitna River (ISR Study 9.7). A total of 33 Chinook juvenile and 57 Chinook
fry microhabitat measurements were recorded, with nearly half (42%) of the total observations
occurring in side slough macrohabitat areas (Table 5.5-1). Side channel and tributary delta
macrohabitats had nearly equal numbers of observations with 16 and 12, respectively (Table 5.5-
1). Just over 60 percent of the Chinook salmon rearing observations occurred during the late
July (23-30) and early August (6-13) sampling effort (Table 5.5-3).
Microhabitat depth measurements of Chinook fry utilization ranged from 0.5-3.5 feet with the
highest frequency occurring at a depth of 0.9-1.1 feet (ISR Study 8.5, Appendix G). For
velocity, fry utilization ranged from 0.1-1.3 feet per second (fps) with the highest frequency
occurring at a velocity of 0.1 fps. Chinook juveniles were most frequently observed in slightly
deeper water with depths ranging from 0.3-4.1 feet with peak utilization occurring at a depth of
0.9 feet (ISR Study 8.5, Appendix G). The range of observed velocity utilized by Chinook
juveniles was also higher at 0.1-2.3 fps with the highest frequency occurring at velocities of
0.1 fps. Although substrate utilization for juvenile Chinook was greatest for the “fines” particle
size (Table 4.5-5), substrate utilization for Chinook fry was highest for small cobble. There were
a few observations at nearly every substrate size for both the fry and juvenile life stages.
5.5.4.2. Chum Salmon
Observations of chum salmon spawning (n=346) were widely distributed throughout the Middle
River Segment of the Susitna River, with observations in 5 of the 7 Focus Areas and extensive
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spawning (57 percent) also observed in areas outside of the Focus Areas (Table 5.5-1). Nearly
80 percent of the chum spawning observations occurred in side channel and side slough
macrohabitat types. Upland slough areas had the next highest number of chum spawning
observations at 51. Only 14 chum salmon fry and 2 juvenile chum were observed during the
2013 HSC/HSI surveys (Table 5.5-1).
Depth utilization by spawning chum salmon ranged from 0.3-3.3 feet with the highest frequency
occurring at 0.9 feet (ISR Study 8.5, Appendix G). For velocity, spawning utilization ranged
from 0.1-1.9 fps with the highest frequency occurring at the lowest measured velocity of 0.1 fps.
Like spawning sockeye salmon, spawning chum were generally observed in side channel and
side slough macrohabitat areas, which generally have low mean column velocities. Substrate
utilization ranged from fines to large cobble with the highest frequency occurring in areas with
large gravel substrates. For chum fry, water depth utilization ranged from 0.3-3.7 feet (ISR
Study 8.5, Appendix G). Water velocity utilization ranged from 0.1-0.7 fps with the highest
frequency occurring at 0.1 fps. Substrate utilization for chum fry ranged from fines to boulder
sized substrate with the highest frequency of use found in areas with fine sediment.
5.5.4.3. Coho Salmon
There were only three coho salmon spawning observations in the Middle River Segment of the
Susitna River during the 2013 HSC/HSI surveys (Table 5.5-1). All three observations were
made in Focus Area -128 (Slough 8A) in an area that had previously been used by chum salmon
for spawning. The observations were completed during the final HSC sampling session for the
season in late September and so it is unknown if additional coho spawning occurred after that
time (Table 5.5-3). Due to the small sample size (n=3) no effort was made to analyze the data.
A total of 57 juvenile and 98 coho fry microhabitat measurements were recorded (Table 5.5-1).
Coho fry observations were collected in nearly every habitat type with the exception of clear
water plume areas. The largest numbers of measurements were made in upland slough, side
slough, and tributary mouth/delta habitat areas (Table 5.5-1). For juvenile coho, approximately
59 percent of the observations were made in upland sloughs with lesser numbers of observations
in side slough and tributary habitat areas (Table 5.5-1). Coho rearing observations were made in
all seven of the surveyed Focus Areas with the highest number of HSC/HSI measurements
collected in FA-104 (Whiskers Slough) and FA-141 (Indian River). Coho salmon rearing
observations occurred during the entire summer sampling period with the largest number of
observations occurring from mid-July through mid-September (Table 5.5-3).
Microhabitat depth measurements for coho fry utilization ranged from 0.3-3.3 feet with the
highest frequency occurring at a depth of 0.9 feet (ISR Study 8.5, Appendix G). For velocity, fry
utilization ranged from 0.1-1.7 fps with the highest frequency occurring at a velocity of 0.1 fps.
Coho juvenile were most frequently observed in slightly deeper water with depths ranging from
0.3-4.5 feet with peak utilization occurring at depths from 1.5-1.7 feet (ISR Study 8.5, Appendix
G). The range of observed velocity utilized by coho juvenile was slightly lower than for fry at
0.1-1.5 fps with the highest frequency occurring at velocities of 0.1 fps. 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 was the highest for the fines substrate size.
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5.5.4.4. Pink Salmon
Pink salmon spawning in tributary and tributary mouth habitat types accounted for nearly 90
percent of the total number (n=59) of spawning measurements (Table 5.5-1). No fry or juvenile
pink salmon life stages were observed during the 2013 HSC/HSI surveys. The absence of
observations of rearing pink salmon is probably due to the early outmigration of young fish prior
to the start of the 2013 surveys (ISR Study 8.5, Appendix H). Pink salmon spawning HSC
measurements were collected from only one of the seven Focus Areas (FA-144 [Slough 21])
with over 70 percent of the measurements made in areas outside of the Focus Areas (Table 5.5-
1). Approximately 90 percent of the pink spawning observations were made during the August
6-17 sampling session (Table 5.5-3).
Pink salmon spawning depth utilization ranged from 0.3-3.3 feet with the highest frequency of
observations occurring at a depth 0.7 feet (ISR Study 8.5, Appendix G). For velocity, spawning
utilization ranged from 0.1-3.5 fps with the highest frequency occurring at a velocity of 1.3 fps.
The relatively large range of velocities utilized by spawning pink salmon is not surprising since
most (53 of 59) of the observations were made in tributary and tributary mouth/delta habitat
areas, which generally have higher mean column velocities than other off-channel areas.
Substrate utilization ranged from small gravel to small cobble with the highest frequency
occurring in areas with large gravel substrates (ISR Study 8.5, Appendix G).
5.5.4.5. Sockeye Salmon
A total of 182 sockeye spawning utilization measurements was collected during the 2013 surveys
with 80 percent of the observations in side channel and side slough macrohabitats (Table 5.5-1).
Sockeye spawning observations were concentrated in three of the Focus Areas (FA-128 [Slough
8A], FA-138 [Gold Creek], and FA-144 [Slough 21]) accounting for just over 85 percent of the
total number of measurements. Nearly 60 percent of the sockeye spawning redd measurements
were completed during the September 10-17 sampling session (Table 5.5-3). Side channel and
side slough macrohabitat types had the highest number of microhabitat observations (147) for
spawning sockeye. Large gravel substrate was the highest frequency substrate type utilization
for sockeye spawning. Microhabitat use observations were collected for 96 rearing sockeye
salmon with measurements made in all seven Focus Areas except FA-144 (Slough 21). Rearing
sockeye observations were made during each of the seven sampling sessions except for late
September (Table 5.5-3). Over 70 percent of rearing sockeye observations were concentrated in
side channel and side slough macrohabitat types (Table 5.5-1).
Sockeye spawning depth utilization ranged from 0.3-3.3 feet with the highest frequency
occurring at 1.5 feet (ISR 8.5, Appendix G). For velocity, spawning utilization ranged from 0.1-
2.5 fps with the highest frequency occurring at a velocity of 0.1 fps. Microhabitat depth
measurements for sockeye fry utilization ranged from 0.1-3.3 feet with the highest frequency
occurring at a depth of 0.7 feet. For velocity, fry utilization ranged from 0.1-1.7 fps with the
highest frequency occurring at a velocity of 0.1 fps (ISR Study 8.5, Appendix G). Sockeye
juveniles were most frequently observed in slightly deeper water with depths ranging from 0.7-
3.5 feet with peak utilization occurring at depths of 1.3 feet (ISR Study 8.5, Appendix G). The
range of observed velocities utilized by sockeye juveniles was slightly lower than for fry at 0.1-
0.5 fps with the highest frequency occurring at velocities of 0.1 fps. Although substrate
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utilization for both the fry and juvenile life stages occurred over a wide range of particle sizes,
the frequency of use by both life stages was the highest for the fines substrate size (ISR Study
8.5, Appendix G).
5.5.4.6. Arctic Grayling
Observations of Arctic grayling were limited to the adult, juvenile, and fry life stages as no
spawning was observed. Arctic grayling was observed in all seven of the surveyed Focus Areas
and in each of the eight macrohabitat types (Table 5.5-1). Of the 193 Arctic grayling
observations, 114 were for the fry life stage, 41 for juvenile, and 4 adult (Table 5.5-1). Arctic
grayling microhabitat use measurements were completed in all sampling sessions except late
September (Table 5.5-3).
Depth utilization by juvenile grayling ranged from 0.5-3.5 feet with the highest frequency
occurring at 0.5 feet (ISR Study 8.5, Appendix G). For velocity, juvenile utilization ranged from
0.1-2.9 fps with the highest frequency occurring at the lowest measured velocity of 0.1 fps.
Substrate utilization ranged from fines to boulder with the highest frequency found in areas with
fine substrate. For grayling fry, water depth utilization ranged from 0.5-3.7 feet with the highest
utilization at 0.9 feet (ISR Study 8.5, Appendix G). Water velocity utilization ranged from 0.1-
2.3 fps with the highest frequency occurring at 0.1 fps. Substrate utilization for grayling fry was
similar to the juvenile life stage ranging from fines to boulder with the highest frequency of use
found in areas with fine sediment.
5.5.4.7. Longnose Sucker
Observations of longnose sucker were limited to the adult, juvenile, and fry life stages as no
spawning fish were observed. Longnose sucker was observed in all seven of the surveyed Focus
Areas and in six of the eight macrohabitat types (Table 5.5-1). Of the 164 longnose sucker
observations, 71 were for the adult life stage, 52 for juvenile, and 41 fry (Table 5.5-1). Longnose
sucker microhabitat use measurements were completed in all sampling sessions except late
September (Table 5.5-3).
Depth utilization by adult longnose sucker ranged from 0.5-3.1 feet with the highest frequency
occurring at 0.9 feet (ISR Study 8.5, Appendix G). For velocity, adult utilization ranged from
0.1-2.9 fps with the highest frequency occurring at 0.1 fps. Substrate utilization ranged from
fines to bedrock with the highest frequency found in areas with fine substrate. Juvenile longnose
sucker depth utilization ranged from 0.3-3.5 feet with the highest frequency occurring at 1.1 feet
(ISR Study 8.5, Appendix G). For velocity, juvenile utilization ranged from 0.1-1.9 fps with the
highest frequency occurring at 0.1 fps. For longnose sucker fry, water depth utilization ranged
from 0.5-2.5 feet with the highest frequency occurring at 0.9 feet (ISR Study 8.5, Appendix G).
Water velocity utilization ranged from 0.1-0.5 fps with the highest frequency occurring at 0.1
fps. Substrate utilization for longnose sucker fry and juvenile was very similar ranging from
fines to large cobble with the highest frequency of use found in areas with fine sediment.
5.5.4.8. Whitefish
Due to the difficulty in distinguishing between early life stages (fry and juvenile) of round and
humpback whitefish, all microhabitat use observations for the two species have been lumped into
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a generic grouping of “whitefish.” Observations of whitefish were limited to the adult, juvenile,
and fry life stages as no spawning was observed. Whitefish were found in all seven of the
surveyed Focus Areas and in each of the eight macrohabitat types (Table 5.5-1). Of the 106
whitefish observations, 28 were for the adult life stage, 38 juvenile, and 40 fry (Table 5.5-1).
Depth utilization by adult whitefish ranged from 0.5-2.9 feet with the highest frequency
occurring at 0.9 feet (ISR Study 8.5, Appendix G). For velocity, adult utilization ranged from
0.1-2.5 fps with the highest frequency occurring at the lowest measured velocity of 0.1 fps.
Substrate utilization ranged from fines to boulder with the highest frequency found in areas with
fine substrate. Whitefish juvenile depth utilization ranged from 0.5-2.7 feet with the highest
frequency occurring at 1.1 feet (ISR Study 8.5, Appendix G). For velocity, juvenile utilization
ranged from 0.1-2.9 fps with the highest frequency occurring at the lowest measured velocity of
0.1 fps. For whitefish fry, water depth utilization ranged from 0.5-3.3 feet with the highest
frequency occurring at 1.1 feet (ISR Study 8.5, Appendix G). Water velocity utilization ranged
from 0.1-2.9 fps with the highest frequency occurring at 0.1 fps. Substrate utilization for both
the fry and juvenile life stages of whitefish occurred over a wide range of particle sizes with the
highest frequency of use by both life stages in the fines substrate size.
5.5.4.9. Rainbow Trout, Burbot, Arctic Lamprey, and Dolly Varden Char
A combined total of 56 HSC/HSI measurements was made for rainbow trout, burbot, Arctic
lamprey, and Dolly Varden during the surveys; (Table 5.5-1). The lowest number of
microhabitat measurements was for Arctic lamprey with only one measurement followed by
rainbow trout with only 13 observations. No spawning observations were made for any of these
species. Over 70 percent of the observations for these four species occurred in side channel,
upland slough, and tributary macrohabitats (Table 5.5-1). Rainbow trout were the most widely
distributed of the four species with observation in all seven of the sampled Focus Areas. As for
habitat use, rainbow trout had the most diverse use and were observed in six of the eight
macrohabitat types. Due to the limited number of observations, no attempt was made to develop
frequency histograms for these four species.
5.5.5. Habitat Availability Data Collection
Both microhabitat utilization and availability data were collected during each sampling event.
Microhabitat availability data will be combined with habitat utilization data for developing
species and life stage habitat preference curves. Collection of habitat availability data allows
modeling of fish presence/absence as a function of single or multiple parameters (e.g., water
depth, velocity, cover, water quality, temperature, and groundwater upwelling) using
measurements at locations where fish were not observed, and utilization measurements as
locations where fish were observed (Manly et al 1993).
Habitat availability data were collected during each of the 210 sampling events completed during
the 2013 HSC field studies. A total of 3,297 measurements of habitat availability was collected
from within each of the seven Focus Areas and from additional areas located outside of the
Focus Areas. The distribution of availability sample sites is identical to the distribution of
habitat utilization measurements as they were both collected from within each of the 50- and
100-meter sampling sites. The number of habitat availability measurements varied by habitat
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type with the highest number of measurements collected from side channel (n=926) and main
channel (n=784) macrohabitat units (Table 5.5-4). The fewest numbers of measurements were
collected in clearwater plume (n=93) and backwater (n=24) macrohabitat units. For availability
measurements within Focus Areas, the highest numbers were collected from FA-104 (Whiskers
Slough) and FA-128 (Slough 8A) and the fewest from within FA-115 (Slough 6A).
Additionally, there were 375 habitat availability measurements collected in areas outside of the
Focus Areas (Table 5.5-4).
Surface water temperature measurements collected during the sampling period (mid-June to late
September) ranged from a low of 3.2°C (side channel habitat) to a high of 26.7°C in an isolated
upland slough area during the height of a mid-July 2013 heat wave (Table 5.5-5). In general, the
lowest water temperatures (<5°C) were associated with side channel, upland slough, and side
slough macrohabitat types (Table 5.5-6). The warmest surface water temperatures (>20°C) were
found in upland slough macrohabitat areas. Most (83 percent) of the surface water temperatures
recorded during the data collection period ranged from 5-15°C (Table 5.5-6). Dissolved oxygen
concentration (mg/L) ranged from a high of 13.0 mg/L to a low of 3.4 mg/L (Table 5.5-5).
Dissolved oxygen levels were generally the highest in main channel and side channel
macrohabitat areas and lowest in upland sloughs (Table 5.5-6). While a few upland slough areas
had dissolved oxygen levels lower than 5 mg/L, most (88 percent) of the measured dissolved
oxygen values in the Middle River Segment of the Susitna River ranged from 5-12 mg/L.
To detect the presence of groundwater upwelling, vertical hydraulic gradient (VHG)
measurements were collected from within each of the 207 sample sites. Positive (>5mm) VHG
values were considered an indication of groundwater upwelling, while negative VHG (<-5mm)
was considered an area of groundwater downwelling. Measurements falling between +5
and -5 mm were considered neutral or an indication of no upwelling or downwelling at the site.
Side slough and upland slough habitats had the highest maximum (+200 and +190) and mean
VHG values of all habitat types. Tributary mouth habitats had the lowest mean VHG values
at -120 mm indicating a strong signature for groundwater downwelling (Table 5.5-5). Forty-nine
percent of all habitat availability measurements indicated the presence of groundwater upwelling
with side channel, side slough, and upland slough macrohabitat areas having the largest number
of positive measurements (Table 5.5-6). Main channel habitats had the highest number of
neutral and negative VHG values.
The conductivity (or specific conductance) of water is a measure of its ability to conduct
electricity and is generally linked to the quantity of total dissolved solids in water. Conductivity
values in the Middle River Segment ranged from a high of 381 µs/cm to a low of 19 µs/cm
(Table 5.5-5). The majority (60 percent) of conductivity values ranged from 87-173 µs/cm with
a mean of 146 µs/cm (Table 5.5-6). Tributary and clearwater plume habitats had the lowest
mean conductivity values at 44 and 69 µs/cm, respectively.
5.5.6. Habitat Utilization Frequency Histograms/HSC/HSI Curve Development
As noted in ISR 8.5, Section 5.5, histogram plots were developed for all species for which
sufficient observations were made to adequately demonstrate a range of microhabitat use (ISR
Study 8.5, Appendix G). Each histogram plot displays the normalized frequency (highest count
set to equal 1.0) of microhabitat use over the range of measured values. For those species and
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life stages where data are available, results of the 2012 HSC/HSI sampling and curves developed
from the 1980s surveys are presented on the same plot as the 2013 frequency analysis.
5.5.7. Methods for HSC/HSI Curve Development
Development of final habitat preference curves is scheduled for next year of study. Several
different models are currently being tested for use in preference curve development, including
univariate, multivariate, and polynomial regressions. Each of these models has the ability to
predict fish presence/absence as a function of several different variables, including water depth,
velocity, substrate, cover, upwelling, and water quality. A simplified example of the use of
univariate-logistic modeling to predict the preference of depth, velocity, and substrate habitat use
by spawning chum sampling is presented in Figure 5.5-9 and Figure 5.5-10. For depth suitability
(upper plot), the impact of using preference instead of utilization is to increase the suitability for
greater depths (Figure 5.5-9). This occurred because there were fewer overall habitats sampled
in deeper water. Only a small number of locations with deep water were utilized by spawning
chum, but they were a relatively large proportion of the overall deep water habitats that were
available. The best-fit logistic model for depth was: log �𝑝1−𝑝�= −3.6 +7.4 ∗𝑑𝑒𝑝𝑡ℎ−6.9 ∗𝑑𝑒𝑝𝑡ℎ2 +2.5 ∗𝑑𝑒𝑝𝑡ℎ3 −0.33 ∗𝑑𝑒𝑝𝑡ℎ4 ,
where
log = natural logarithm,
p = probability of observing a redd, and
depth = depth in feet.
The second best model for depth, a third-order polynomial model, is also displayed for
comparison (Figure 5.5-9).
For velocity (lower plot) the impact of using preference instead of utilization was to shift the
peak suitability to the right (Figure 5.5-9). This occurred because there were fewer overall
habitats sampled in faster water. Again, although only a small number of locations in faster
water were utilized, a relatively large proportion of the overall fast water habitats were sampled.
The best-fit model for velocity was: log �𝑝1−𝑝�= −1.8 + 5.4 ∗𝑣𝑒𝑙−8.4 ∗𝑣𝑒𝑙2 +4.9 ∗𝑣𝑒𝑙3 −1.0 ∗𝑣𝑒𝑙4 ,
where vel = velocity in ft/sec.
The second best model for velocity, a quadratic model, is also plotted for comparison (Figure
5.5-9).
The utilization and preference results for substrate are plotted side-by-side in Figure 5.5-10. The
largest difference between the two methods (utilization vs. preference) is seen for substrate code
= 3, small gravel. There were relatively few utilization sites with small gravel, so this would
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give a smaller suitability value. However, the availability measurements found relatively few
sites that had small gravel, which greatly increased the significance of the spawning taking place
at those sites.
This type of analysis will be completed for all other species and life stages for which sufficient
habitat utilization data are available. Additionally, the modeling will be used to predict habitat
preference for the other variables listed above. Draft habitat preference curves will be presented
to the TWG as part of the Proof of Concept scheduled for 2014.
5.5.8. Winter Habitat Use Sampling
Results of the 2012-2013 winter pilot studies are summarized below; more details are presented
in Technical Memorandum (R2 2014).
5.5.8.1. Water Surface Elevations
Water surface elevations of the Susitna River main channel in FA-104 (Whiskers Slough)
exhibited a long-term downward trend during the period February through April 2013, although
short-term oscillations occurred throughout the measurement period (Figure 5.5-11). Water
levels recorded at side channel site WSC-30 were similar to the main channel (MC-50) in terms
of the long-term downward trend and short-term fluctuations based on comparison of normalized
water levels (Figure 5.5-11). At monitoring sites in side slough and upland slough habitats, the
long- and short-term stage patterns were generally more stable compared to the main channel
(Figure 5.5-11). At most off-channel sites, water elevation changes through the period of
measurement were minimal, and short-term stage fluctuations evident at off-channel monitoring
sites in late March 2013 differed from the main channel in terms of magnitude and duration
(Figure 5.5-11). While short-term stage fluctuations are evident at each site in late March, the
events were typically not as large in magnitude or duration at side slough (WSC-20, WSC-40),
upland slough (SL3A-70), or at side channel (SL3B-50) sites as in the main channel (MC-50)
(Figure 5.5-11). The stage record in Whiskers Creek was substantially different from the
patterns exhibited at all other continuous monitoring sites (Figure 5.5-11). The inlets to side
channel and off-channel macrohabitats in FA-104 (Whiskers Slough) (e.g., Whiskers Slough,
Slough 3A) were not visible due to snow and ice cover during the February through April 2013
effort, so it was not confirmed whether channels were breached by Susitna River main channel
streamflow.
Comparison of water surface levels within FA-128 (Slough 8A) indicated similar stage responses
between upland slough (US2-10) and side slough (SL8A-15) macrohabitats in terms of the
magnitude and timing of seasonal and daily trends Figure 5.5-12. In addition, stage fluctuations
at FA-128 (Slough 8A) off-channel sites were generally similar to the main channel Susitna
River stage response during late May to early August 2013 based on comparison of normalized
water levels among FA-128 (Slough 8A) sites and the recorded stage at the USGS gage at Gold
Creek (No. 15292000) (Figure 5.5-12). Large-scale episodic stage fluctuations in the main
channel measured at the USGS gage at Gold Creek (No. 15292000) during ice break-up in May
and June 2013 were reflected at both off-channel monitoring sites, although the magnitude of
such events was lower at the FA-128 (Slough 8A) sites compared to the main channel (Figure
5.5-12). The inlet of Slough 8A was not breached by Susitna River main channel flow during
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the March and April 2013 data collection trips and the upstream extent of surface water flow in
Slough 8A extended approximately to site SL8A-50 (Figure 4.5-3). The timing and duration that
the Slough 8A inlet was breached during spring flood events in May and June 2013 has not been
established.
5.5.8.2. Water Temperature, Conductivity and Dissolved Oxygen
Surface and intergravel water temperatures differed among macrohabitat types in FA-104
(Whiskers Slough) during the 2012-2013 winter pilot study based on data collected at the nine
continuous monitoring sites. Surface water temperatures recorded during February through April
2013 were near 0°C at main channel site MC-50, generally below 2°C at sites influenced by
Whiskers Creek (WC-10 and WSL-20), and ranged between approximately 1-4°C at off-channel
sites (Figure 5.5-13, Figure 5.5-14, and Figure 5.5-15). Intergravel water temperatures were
warmer than surface water at all sites, although the difference at the main channel site was
negligible. The largest observed differential between surface and intergravel water temperature
was more than 3°C at site WSC-30 (Figure 5.5-13). Continuous intergravel temperature data
were not collected at FA-128 (Slough 8A) due to ice formation within the intergravel insertion
equipment during the March 2013 effort, which precluded deployment of temperature loggers
into the channel substrate.
Diurnal fluctuations of water temperature were common among FA-104 (Whiskers Slough)
monitoring sites, but were generally more prevalent among off-channel and tributary monitoring
sites relative to mainstem locations (Figure 5.5-13, Figure 5.5-14, and Figure 5.5-15). Diurnal
temperature changes were apparent throughout the vertical gradient at nearly all off-channel and
tributary sites and the magnitude of daily fluctuation exceeded 1°C in Whiskers Creek, Whiskers
Slough, and at sites upstream of Whiskers Slough (SL3B-10, SL3A-70) (Figure 5.5-13, Figure
5.5-14, and Figure 5.5-15). At side channel site WSC-30 and side slough site CFSL-10, a
fluctuating daily temperature pattern was evident near the substrate surface (-5 cm), but was
negligible at intergravel depths of 20 cm and 35 cm (Figure 5.5-13). Diurnal temperature
variations were not apparent at main channel site MC-50 (Figure 5.5-13).
There was no clear effect of Susitna River main channel water level fluctuations on intergravel
temperatures at the three FA-104 (Whiskers Slough) sites that were known to support salmon
spawning in fall 2012 (WSC-30, WSL-20, WC-10). Although water levels at the side channel
site WSC-30 were variable throughout the measurement period, and reflected the main channel
(MC-50) stage response, intergravel water temperatures at WSC-30 were not visibly affected by
such changes in water level (Figure 5.5-16). At side slough site WSL-20, stage was stable
relative to the main channel and surface and intergravel water temperatures at WSL-20 did not
appear to change in relation to main channel stage fluctuations (Figure 5.5-16). At Whiskers
Creek site WC-10, main channel stage fluctuation did not visibly affect stage or water
temperature (surface or intergravel) (Figure 5.5-16).
Instantaneous measurements of surface water temperature recorded in April 2013 at FA-104
(Whiskers Slough) were consistent with data recorded at continuous sites in that surface water
was generally warmer in side slough and upland slough macrohabitats relative to Susitna River
main channel and side channel sites (Figure 5.5-17). Conversely, specific conductance at
mainstem instantaneous measurement sites was typically higher than in off-channel and tributary
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areas (Figure 5.5-17). Exceptions to this general trend were at side channel site SL3B-10, which
exhibited lower specific conductance and higher water temperature than other side channel sites,
and side slough site CFSL-10, at which the recorded specific conductance was more similar to
mainstem habitat than other side slough habitats (Figure 5.5-17).
At FA-128 (Slough 8A), instantaneous water quality measurements measured during April 2013
suggested that side slough and upland slough macrohabitats were generally warmer relative to
main channel and side channel areas, but specific conductance was not substantially different
among habitats (Figure 5.5-17). Specific conductance was lower within Slough 8A (side slough)
relative to main channel, side channel, and upland slough macrohabitats (Figure 5.5-18). Bank
seepage flow at side channel sites was characterized by warmer temperature and slightly lower
conductance than adjacent surface waters, whereas in upper Slough 8A (SL8A-50) bank seepage
was similar to the main water body in terms of temperature and specific conductance (Figure 5.5-
18).
Intergravel dissolved oxygen recorded at approximately 20 cm below the substrate surface at a
known 2012 salmon-spawning site in FA-128 (Slough 8A) (SL8A-15) was generally stable
(approximately 5.2 mg/L) through late March and April 2013 (Figure 5.5-19). Water
temperature recorded by the dissolved oxygen logger was similarly stable through the period of
measurement with minimal daily fluctuation (Figure 5.5-19). Continuous dissolved oxygen data
recorded at FA-104 (Whiskers Slough) site SL3B-10 appeared to be erroneous (measurements
fluctuated widely) and are not shown here. Intergravel temperature recorded by the dissolved
oxygen logger at FA-104 (Whiskers Slough) site SL3B-10 closely reflected temperature values
measured at a similar depth by an intergravel temperature logger at the site.
5.5.8.3. Fish Observations and Habitat Utilization
Underwater fish behavior observations and fish capture efforts during the February through April
2013 study period indicated that juvenile fish were active during both day and night periods in
FA-104 (Whiskers Slough) and FA-128 (Slough 8A). Fish activity was observed during daytime
and nighttime opportunistic underwater surveys of ice-covered side channel, side slough, and
upland slough macrohabitats in which optical video cameras were used to actively scan the
channel from one or more fixed positions in the ice (see ISR Study 9.6). No distinct difference
in fish activity was apparent during day and night surveys during optical video camera surveys;
however, DIDSON sonar surveys in FA-104 (Whiskers Slough) near site WS-70 identified
directional movements of fish at dusk and at dawn that were not apparent at other times (see ISR
Study 9.6). Based on daytime and nighttime electrofishing surveys of open-water areas, total
fish capture at night was typically higher than daytime capture at sites sampled during both
diurnal periods in FA-104 (Whiskers Slough) (SL3A-71) and FA-128 (Slough 8A) (SSC-20,
SC8A-28, SL8A-10, US2-10) (Table 5.5-7).
A total of 29 HSC/HSI observations of juvenile Chinook and coho habitat utilization was
recorded during electrofishing sampling efforts in open-water areas of FA-104 (Whiskers
Slough) and FA-128 (Slough 8A) in March and April 2013 (Table 5.5-8). Of this total, 26
observations were recorded for juvenile Chinook and three for juvenile coho salmon (Table 5.5-
8). No HSC data were recorded in ice-covered areas in association with underwater optical
video surveys.
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5.5.9. River Productivity
In 2013, data were collected in support of HSC/HSI models as described in ISR Study 8.5,
Section 4.5 (River Productivity). These data were collected to assist in generating HSC/HSI
criteria for Susitna River benthic macroinvertebrate and algae habitats for use in predicting
potential changes in these habitats downstream of the proposed dam site. Approximately 300
Hess samples were collected with depth, velocity, and substrate composition measurements
(Table 5.5-9). In addition, 150 samples of large woody debris (“snags”) were collected with
depth, velocity, and surrounding substrate composition estimates; 1,745 rock locations taken for
composite algae samples recorded depth and velocity (Table 5.5-9). A detailed description of the
location and timing of sampling is provided in the River Productivity Study (ISR Study 9.8).
At this time, data processing and analysis needed for HSC/HSI curve/model development for
macroinvertebrates and algae is not yet complete. Draft HSC/HSI curves and model
development for macroinvertebrates and algae are scheduled for completion following the
second year of study and prior to the USR.
5.5.10. Draft Periodicity Tables
During 2013, AEA developed draft periodicity tables to describe the temporal periods which
each target species and life stage are expected to occur in the Project area (ISR Study 8.5,
Appendix H). These tables were based largely on information from the 1980s studies as
presented in Technical Memorandum 5 7of R2 2013e, supplemented with contemporary
information provided in ADF&G reports prepared in the 2000s (e.g., Merizon et al. 2010). To
the extent possible, the timing of use by macrohabitat type (main channel, side channel, side
slough, upland slough, tributary mouth, and tributary; see ISR Study 9.9 for detailed description
of habitat types) was provided by species and life stage for each segment (Upper, Middle,
Lower) based on reviews of these studies. However, habitat utilization data for some species
and/or life stages in the Susitna River are sparse; in these cases, the available information was
consolidated among Susitna River segments and/or was supplemented by data not specific to the
Susitna Basin (e.g., Morrow 1980). The draft periodicities will be reviewed and modified based
on results of fish distribution sampling and input from agency participants. A detailed
description of the data sources and rationale for each individual species periodicity table is
presented in the Technical Memorandum 5 of R2 (2013e).
5.5.11. Biological Cues Study
The objective of this exploratory analysis completed by AEA was to look for general
relationships between hydrologic variables and biological responses of salmon species, in this
case Chinook salmon, which may be relevant to the Susitna River. The analysis centered on two
glacially fed river systems, the Taku and Stikine rivers. These systems were deemed the most
suited for drawing inferences related to hydrologic variables and attributes of salmon escapement
that might pertain to the Susitna River system, due to their glacial origin and the length of both
7 Technical Memorandum 5 – Selection of target species and development of species periodicity information for the
Susitna River . In R2 (2013e).
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their hydrologic and escapement records. Full results of the biological cues study are presented
in ISR Study 8.5, Appendix B.
Overall, there were a number of weak to moderate correlations found between productivity or
run-timing metrics and hydrologic indices for the Taku and Stikine rivers. For the Taku River,
observed relationships are as follows:
• There were more returns per spawner when a wider range of flows occurred during adult
migration.
• There were more returns per spawner when there were high winter flows combined with
no large summer-flow decreases that could result in trapping events.
• There were more smolts per spawner when the summer low flow was moderate or
relatively high.
• The duration of the Chinook salmon run was longer when flows were more variable.
For the Stikine River, observed relationships are as follows:
• Total returns tended to be higher when the winter minimum flow was higher.
• Total returns tended to be lower when PDO was higher during early ocean rearing.
• There tended to be fewer smolts per spawner when there were large flow decreases
during the spawning period.
• The duration of the Chinook salmon run was longer when flows were more variable.
• The median date of the run was earlier when there were late high flows.
In general, significant correlations were inconsistent for similar indices analyzed from the Taku
River and Stikine River datasets. Thus, applying the results from the Taku or Stikine rivers to
other Chinook salmon populations, such as in the Susitna River, could be erroneous and should
be done with caution. However, there was one consistent result for the two rivers: variable flows
during the spring and summer were correlated with broader upstream migration periods. Upon
further investigation, it was found that run duration was negatively correlated with total counts at
the fishwheels or test fishery locations for both rivers; i.e., a more prolonged migration period
was associated with smaller total counts. From these two relationships, i.e., 1) more variable
flows in spring/summer were associated with broader/longer upstream migration periods; and
2) broader/longer migration periods were associated with smaller runs), it could be concluded
that more consistent flows during the migration period may lead to larger runs. However,
comparing flow range to total returns or returns per spawner does not result in significant
correlations for either river. Therefore, the applicability of this relationship between flow
variability and length of migration period to the Susitna River is unclear.
5.5.12. Relationship between Microhabitat Use and Fish Abundance
As noted in ISR Study 8.5, Section 4.5, all data (and samples from water quality sampling)
necessary for this evaluation were collected during the 2013 field season as part of sampling
efforts associated with Fish Distribution and Abundance (ISR Study 9.5), Water Quality (ISR
Study 5.5), River Productivity (ISR Study 9.5), and Groundwater (ISR Study 7.5) studies. AEA
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has requested data from each of these studies, but is still waiting to receive some data and results,
primarily from the studies that included a laboratory analysis component (e.g., Water quality
sampling, River Productivity). The status of obtaining all data necessary to complete this
analysis is summarized in Table 5.5-10. Once all data are obtained, site-specific data will be
spatially located onto Focus Area maps to identify if overlaps are evident between specific
microhabitat variables and fish abundance. AEA will complete a statistical analysis of the data
to detect possible relationships between the variables and fish distribution and abundance
information. The analysis proposed for completing this evaluation is described in ISR Study 8.5,
Section 7.5.
5.5.13. Stranding and Trapping
No formal stranding and trapping surveys were completed in 2013. Informal, opportunistic
surveys of stranded or trapped fish were completed in the Middle River Segment during
completion of HSC/HSI surveys and Focus Area substrate characterization surveys (ISR Study
8.5, Section 4.6). No stranded or trapped fish were noted during any of these surveys.
Opportunistic observations were also made in the Lower River Segment near PRM 95 during a
June 13-14, 2013 site reconnaissance during which 3-4 unidentified salmonids were observed
trapped in a pool disconnected from the main channel of the river. No stranded fish were
observed during that survey. For the next year of study, only opportunistic stranding and
trapping field surveys are scheduled (ISR Study 8.5, Section 7.5). AEA will discuss the need for
more formalized stranding and trapping surveys with the resource agencies. If stranding and
trapping surveys are not needed, ramping criteria developed in Washington State (Hunter 1992)
will be proposed as fallback criteria during effects analyses. This was noted during the May 17,
2013 TWG meeting.
5.6. Habitat-Specific Model Development
5.6.1. Habitat Model Selection
AEA selected and has proceeded with development of 2-D hydraulic models for seven of the ten
Focus Areas in the Middle River Segment; the upper three Focus Areas were not measured due
to access restrictions. Once developed, the 2-D model will provide the platform and analytical
engine for conducting a variety of habitat analyses, including basic PHABSIM analysis to
compute habitat flow relationships for different species and life stages of fish and
macroinvertebrates using HSC/HSI criteria (ISR Study 8.5, Section 5.5), effective
spawning/incubation analysis, stranding and trapping analysis, varial zone modeling, and habitat
connectivity/breaching flow analysis. Due to the complexity of the channel network in the
Lower River Segment, AEA selected the 1-D hydraulic model HEC-RAS Version 4.1 to
simulate water surface elevations coupled with PHABSIM for determining habitat – flow
relationships for different species and life stages at discrete locations, and has proceeded with
data collection for those models (R2 2013b).
5.6.2. Field Coordination and Collection of Physical and Hydraulic Data
Field surveys occurred in 2013 and were closely coordinated between and among the different
resource leads to ensure that data necessary for developing the respective hydraulic and habitat
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models was being collected. A description of the types of data and methods used in collecting
the data are described in ISR Study 8.5, Section 4.6.
5.6.2.1. Boundary Condition Transects
Data were collected at each of the boundary condition transects as part of the hydrologic data
collection field activities described in ISR Study 8.5, Section 4.3. The primary field data
collected included; cross-sectional surveys to define channel topography and hydraulic controls;
velocity and discharge measurements collected using an ADCP system; water surface elevation
measurements taken during discharge measurements; and documentation of substrate types and
roughness characteristics (ISR Study 8.5, Section 4.6).
Data collected at each of the boundary condition transects will be used to compute the energy
slope, velocity, depth, and other hydraulic variables at each cross-section for use in development
of the 2-D hydraulic models. Additional data that will be used for defining boundary conditions
will be provided by the Open-water Flow Routing Model (ISR Study 8.5, Section 5.3) and the
River 1D Ice Processes Model (ISR Study 7.6).
5.6.2.2. 2-D Modeling
In 2013, AEA collected bathymetry and hydraulic data for 2-D models at the seven Focus Areas
between PRM 104 and PRM 145 in 2013 (ISR Study 6.6 and ISR Study 8.5, Section 4.3). Maps
of the seven measured Focus Areas (FA-104 [Whiskers Slough], FA-113 [Oxbow 1], FA-115
[Slough 6A], FA-128 [Slough 8A], FA-138 [Gold Creek], FA-141 [Indian River], and FA-144
[Slough 21]), showing fine and coarse mesh overlays, channel inlet and outlet measurement
locations, and calibration transects are shown in Figure 5.6-1 through Figure 5.6-7. The
bathymetry data were collected using boat-mounted equipment in the main channel and side
channels with sufficient depth to maneuver. Bathymetry and topography data were collected via
wading in areas too shallow for boat mounted equipment and on areas above the water surface.
The survey data were distributed to the Geomorphology Study (ISR Study 6.6) for development
of the 2-D hydraulic models.
AEA also collected substrate and cover data at the seven Focus Areas in September, 2013. The
field crews consisted of a boat crew for main channel/deep water habitats and a ground crew for
shallow habitats and off-channel habitats. As noted in ISR Study 8.5, Section 4.6, the substrate
and cover data collection followed the same protocols as the HSC development (ISR Study 8.5,
Section 4.5). At each Focus Area, the field crew used laminated aerial photographs of the study
area as the base map to record substrate and cover characteristics. Polygons of homogeneous
substrate and cover type were drawn on the photographs and the dominant and subdominant
substrate in the polygon recorded.
Photographs of data sheets were taken after each field day as a backup copy of the field data.
The field data and polygons for each Focus Area were subsequently digitized and incorporated
into GIS and will be used in developing substrate maps for the 2-D habitat analysis. The
substrate maps will include geo-referenced polygons of substrate for the 2-D model domain in
each of the Focus Areas. The GIS analysts completed the preliminary data entry for FA-104
(Whiskers Slough) and FA-128 (Slough 8A) in 2013, and will complete the geo-referenced
substrate maps for the other five measured Focus Areas during next year. The preliminary data
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entry will undergo standard QA/QC procedures prior to use in the 2-D habitat model. The
substrate maps developed for each Focus Area will be cross-checked/referenced with the results
of the substrate characterization being conducted by the Geomorphology study (ISR Study 6.6).
5.6.2.3. 1-D Single Transect Modeling
The methods applied in 2013 for the collection of single transect data to support both the
refinement of the Open-water Flow Routing Model and development of 1-D hydraulic models to
support PHABSIM analysis are described in ISR Study 8.5, Section 4.6. Application of single
transect modeling represents the primary method for deriving habitat-flow relationships in the
Lower River Segment. In that segment, single transects were located across a range of
macrohabitat types at five sites established between PRM 92.9 and PRM 97 to support
development of 1-D hydraulic models and completion of a 1-D PHABSIM analysis (ISR Study
8.5, Section 4.6).
5.6.3. Model Development
5.6.3.1. 2-D Modeling
As noted in ISR Study 8.5, Section 4.6, there are currently two 2-D hydraulic models being
considered for application in the Focus Areas, SRH-2D, a model from the US Bureau of
Reclamation and River2D a model from the University of Alberta. These models were selected
as candidates and are being evaluated for their potential applicability for the Geomorphology
studies (ISR Study 8.5, Section 6.6). Only one of these models will ultimately be used for both
the geomorphology and habitat modeling, but both are mentioned in this ISR.
Development of preliminary 2-D hydraulic models began in Q2 2013. Both of the models have
the capability to vary the mesh size allowing the size of the model element to be varied.
Selection of the appropriate mesh size for the 2-D Bed Evolution Model 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
limitations on the maximum number of elements that the model can simulate. Mesh size in near
shore areas, side channels, and side sloughs that are relatively complex and contain a variety of
habitat structures require a smaller mesh to provide greater resolution of discrete habitat features;
a preliminary mesh size for these areas is 6.56 feet (2 meters). In contrast, the mesh size in the
larger main channel areas that are morphologically uniform can be larger; a preliminary mesh
size for these areas is 32.8 feet (10 meters).
At some Focus Areas, two separate model meshes may need to be developed. One mesh would
be used for executing the 2-D Bed Evolution Model (ISR Study 6.6) and 2-D River Water
Quality Model with Enhanced Resolution (ISR Study 5.6), which require significantly 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. Calibration
of the 2-D hydraulic models for the Middle River Segment Focus Areas was initiated in 2013.
Preliminary 2-D hydraulic model results from FA-104 (Whiskers Slough) were developed to
support presentations at the November 13-15, 2013 IFS-Technical Team Riverine Modelers
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Meeting (Tetra Tech 2013f). Calibrated hydraulic models for FA-128 (Slough 8A) will be
developed and used in the Proof of Concept analysis in 2014.
The SRH-2D or River2D models will provide outputs of depth, velocity, and water surface
elevations for a given flow, over an entire Focus Area. These outputs will be combined with the
HSC/HSI curves and input to the 2D – PHABSIM based habitat models to calculate habitat
quantities by species and life stage under different flows (ISR Study 8.5, Section 5.6).
5.6.3.2. 1-D Single Transect Modeling
Habitat modeling in the study sites located in Lower River Segment (ISR Study 8.5, Section 4.2)
of the Susitna River is being completed using a single transect 1-D modeling approach. For this,
the one-dimensional HEC-RAS (Version 4.1) model was selected to conduct initial hydraulic
calibrations and to provide simulated water surface elevations for habitat modeling at each fish
habitat transect (ISR Study 8.5, Section 4.6). HEC-RAS was selected since it can readily handle
multiple inflow points within the model domain, which is needed for the Lower River fish
habitat sites, and it can be integrated with the Open-water Flow Routing Model. This model will
provide output that will be combined with HSC/HSI data for completing a PHABSIM based
analysis for determining habitat – flow relationships and evaluating other habitat metrics.
Detailed methods applied in the calibration and development of the HEC-RAS models are
described in ISR Study 8.5, Section 4.6.
Calibration of the 1-D hydraulic models was initiated in 2013 and was based on data available as
of December 1, 2013. Two of the five sites were selected for initial model calibration, the Birch
Creek Site to represent a tributary confluence site and the PRM 97 Site to represent a main
channel site. The details of the model calibration are provided in ISR Study 8.5, Appendix I.
These calibrations relied on provisional tributary gaging results and results from Version 1 of the
Open-water Flow Routing Model, and will be updated when new data and model results become
available.
5.6.4. Habitat Evaluation Metrics
5.6.4.1. Weighted Usable Area Habitat Metrics
The 2-D and 1-D hydraulic models will provide input to the PHABSIM based models that
incorporate HSC/HSI criteria allowing for the generation of a variety of different habitat-flow
relationships for different species and lifestages of fish as well as macroinvertebrates. The
metric generated from these types of studies is often expressed as WUA, which represents an
index of habitat area provided at a given flow.
In a traditional PHABSIM analysis the computation of WUA generally only captures three
variables, depth, velocity and substrate (or cover). While this type of PHABSIM analysis will be
applied with both the 1-D and 2-D hydraulic models, other HSC/HSI type metrics will be
integrated into the 2-D hydraulic analysis completed within Focus Areas. This will include
HSC/HSI models pertaining to groundwater upwelling/downwelling, turbidity, and water
temperature, and potentially others identified from the analysis of microhabitat use and fish
abundance (ISR Study 8.5, Section 4.5).
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Because the 2-D hydraulic models do not include a spatial component for habitat analysis at the
macrohabitat or mesohabitat scales, a stand-alone VB model programmed specifically for this
type of analysis, coupled with GIS tools is under development. The VB model combines the
HSC/HSI criteria (including criteria for upwelling/downwelling, temperature, etc.) with the
output for each point/node in the hydraulic model (e.g., depth and velocity) to compute its’
habitat suitability value. The habitat suitability values for each node are then multiplied by the
area of the mesh element to calculate the habitat area for each mesh element over the entire
model domain. A GIS tool is then used to evaluate habitat characteristics in the smaller habitat
areas as subsets of the model domain. The VB model output will include a geo-referenced text
file that includes all the data from the 2-D hydraulic model and the calculated habitat use value
for each element in the model domain. A text file will be generated for each simulated flow.
The model execution sequence will generally occur as follows:
1) Construction and calibration of the 2-D hydraulic models and simulation of a range of
flows as provided in ISR Study 8.5, Section 6.6;
2) Transfer of hydraulic model results to the 2-D habitat modeling using text files (Figure
5.6-8);
3) Construction of habitat suitability functions into the VB model and selection of functions
during model execution. The VB model is opened and the species/life stage is selected
(Figure 5.6-9);
4) Selection of the input hydraulic simulation file; and
5) Model calculation of habitat use values for each element and production of graphic and
tabular results (Figure 5.6-10 and Figure 5.6-11).
These steps are repeated for each species/life stage and each simulation flow. The result is
habitat area for the model domain for the range of simulated flows. This analysis is analogous to
a habitat versus flow analysis generated in a typical PHABSIM study. These habitat use data
will also be used in the GIS tool developed for analysis of the smaller spatial areas in each Focus
Area.
This general process was demonstrated for FA-104 (Whiskers Slough) using the uncalibrated
preliminary output from the SHR-2D hydraulic model provided by the Geomorphology program,
during the November 13-15, 2013 IFS-TT Riverine Modelers Meeting (Miller and R2 2013).
Importantly, the 2-D habitat model is dependent on outputs from several other studies including
Open-water Flow Routing Model, River 1D Ice Processes Model, 2-D hydraulic models,
HSC/HSI criteria, results from Ground water studies regarding upwelling/downwelling, and 2-D
River Water Quality Model with Enhanced Resolution (Figure 5.6-12). The general flow of data
and data dependencies moves from the physical process models to the 2-D habitat models
(Figure 5.6-13).
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5.6.4.2. Effective Spawning/Incubation Habitat Analyses
AEA completed the initial model development for the Effective Spawning/Incubation Habitat
Analyses of the Middle River Segment Focus Areas in 2013 (ISR Study 8.5, Section 4.6). The
Effective Spawning/Incubation Habitat Analyses habitat analysis requires either model output or
data from the 2-D hydraulic models for open-water conditions in the Focus Areas (ISR Study
6.6), 2-D hydraulic modeling of ice processes (ISR Study 7.6), ground water data or processes
(ISR Study 7.5), water quality data or model results (ISR Study 5.6), and HSC/HSI data from the
habitat suitability study (ISR Study 8.5, Section 5.5) (Figure 5.6-14). The temporal analysis of
habitat over time uses the hydrology data from the Open-water Flow Routing Model (ISR Study
8.5, Section 5.4) and the 1-D Ice Processes Model (ISR Study 7.6).
The Effective Spawning/Incubation Model will include the use of the VB habitat model and GIS
tool for the complete analysis. The VB model can be executed prior to the GIS tool to calculate
habitat use at each model element for a specified range of flows. These data sets then are part of
the input to the spatial analysis tool to determine suitability of the habitat in smaller spatial areas
than the entire model domain. The potential or known fish spawning locations can be selected
from within the Focus Area for analysis (Figure 5.6-15).
The 2-D habitat analysis sequence is being implemented in accordance with the steps illustrated
in the Study Plan (Figure 5.6-16). The first steps in the 2-D habitat analysis for effective
spawning/incubation include characterization of ground water and groundwater upwelling.
Groundwater can have a profound influence on the suitability of spawning and incubation
habitats over the winter and the ground water process analysis (ISR Study 7.5) will provide
ground water data for the 2-D habitat analysis. These data will be used for both spatial (selected
areas of certain Focus Areas) and temporal (trends over seasons) analysis (Figure 5.6-17). These
general trends are then applied in the spatial domain of the smaller areas to determine which
areas remain suitable over the entire temporal extent from spawning through incubation (Figure
5.6-18). Spatial areas that remain suitable over the entire temporal extent are then evaluated for
other physical processes (Figure 5.6-19). These physical processes include freezing, dewatering,
scour, and water quality. Open-water 2-D hydraulic modeling (SRH2-D or River 2-D) provides
the data for scour. 2-D ice process modeling provides the data for freezing and dewatering for
ice covered conditions. Water quality modeling provides the data for suitable water quality for
the temporal extent from spawning through incubation (Figure 5.6-20).
The results of the effective spawning/incubation analysis will be presented in both tabular and
spatial formats. The GIS tool converts the tabular, geo-referenced data into shape files for
display and additional analyses. The spatial display can include both habitat use values (Figure
5.6-21) and physical parameters such as depth, velocity, and water surface elevations (Figure
5.6-22). The use of GIS provides an analysis framework that can be used for evaluation and
comparison of spatial changes with and without the project on a scale that is smaller than the
entire model domain.
5.6.4.3. Varial Zone Modeling
Varial zone modeling of the Focus Areas will begin when calibrated 2-D hydraulic models are
completed. Varial zone modeling will use the 2-D hydraulic model output to determine water
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surface elevation at each simulation flow throughout each Focus Area. The change in spatial
area will be calculated using a GIS tool to develop a wetted area versus discharge function. A
flow time series from the Open-water Flow Routing Model will provide the data for the temporal
analysis of changes in the varial zone. The process that AEA will utilize for varial zone
modeling is described in ISR Study 8.5, Section 7.6.
5.6.4.4. Breaching Flows and Habitat Connectivity
Topographic and bathymetry data were collected in the seven Focus Areas of the Middle River
Segment of the Susitna River in 2013 and will be used in development of 2-D hydraulic models
(ISR Study 6.6) and in the analysis of breaching and habitat connectivity within these areas. The
2-D models are based on bed topography and produce water surface elevations over the entire
Focus Area model domain. These water surface elevations can be used to establish the flow
magnitudes in the Susitna River that result in the breaching of off-channel habitat control points
and the inflow of water into the off-channel macrohabitats. In addition, single transect data can
be extracted from the 2-D data to conduct an analysis of water depths at specific locations to
evaluate fish habitat connectivity within a Focus Area. If needed, a single transect analysis can
be completed using a 1-D model developed from data collected within Focus Areas. The
approach and methods AEA will utilize for this analysis are described in ISR Study 8.5, Section
7.6.
As noted in ISR Study 8.5, Section 5.6, the assessment of breaching flows, fish barriers and
connectivity in habitats within the Lower River Segment will be completed based on depths and
velocities at the fish 1-D habitat transects and will focus on the areas around tributary
confluences and the connectivity within braided island complexes and side channels with the
main channel cross-sections. No additional data collection specific to breaching flows, fish
barriers or connectivity was collected at the LR-1 fish habitat sites. Some drying of bar island
complex channels was observed at surveyed transects between high flow conditions and low
flow conditions. No barriers or loss of connectivity for fish movements between the main
channel and side channels or tributary mouths was observed at the 2013 lower river fish habitat
sites at any of the three flow conditions directly observed during field surveys. Additional
transect surveys were completed in 2013 on the Deshka River and at the Deshka River
confluence as a component of the geomorphology study (ISR Study 6.6). The results from that
modeling effort will be used to assess breaching flow and connectivity to the Deshka River
through an assessment of flow depth and velocity at the Deshka River confluence. Temporal and
Spatial Habitat Analyses
5.7. Temporal and Spatial Analysis
Completion of the temporal and spatial analyses is contingent on the acquisition and analysis of
data and subsequent development of models that will be used to assess both temporal and spatial
effects of Project operations. IFS-related data acquisition was initiated in Q2 2013 and will
continue through the next year of study; model development activities are ongoing and will
likewise continue through the next year of study. However, planning activities associated with
development of potential methods and approaches for conducting the temporal and spatial
analyses were completed in 2013. These were initially provided in the Study Plan, discussed
briefly during the IFS-TT riverine Modelers Meeting on November 13-15, 2013, and presented
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in ISR Study 8.5, Section 7.6. Further discussion with the TWG will occur in 2014 and will be
presented as part of the Proof of Concept discussions.
5.8. Instream Flow Study Integration
Study integration efforts are scheduled to contine in the next study season. There were planning
and organizational activities in 2013, that are discussed below. Progress on these topics was also
discussed during the November 13-15, 2013 IFS Technical Team (TT) Riverine Modelers
meeting (AEA 2013). During that meeting, several options for developing a Susitna River DSS
were presented and discussed.
6. DISCUSSION
6.1. IFS Analytical Framework
The IFS analytical framework developed in 2012 was successfully applied in principle
throughout 2013 as studies were implemented to collect data from a range of macrohabitat types
within the Middle River Segment and to a lesser extent in the Lower River Segment. This has
included data associated with discrete transects and monitoring sites, as well as information from
within seven of ten Focus Areas in the Middle River Segment that will be used for evaluating
Project effects across multiple resources. Much of the data collected in 2013 will be used in
developing flow-sensitive models that can be linked with Project operations to evaluate effects
on fish habitat, water quality (ISR Study 5.6), sediment transport (ISR Study 6.6), ice processes
(ISR Study 7.6), groundwater (ISR Study 7.5), and riparian vegetation (ISR Study 8.6).
6.2. River Stratification and Study Area Selection
The Fish and Aquatics IFS stratification and selection of study areas was successfully completed
in 2013 and resulted in the selection of ten Focus Areas in the Middle River Segment and two
study sites in the Lower River Segment. During 2013, data were collected and subsequently
analyzed from seven of the ten Focus Areas in the Middle River Segment and within
Geomorphic Reach LR-1 of the Lower River Segment. The three Focus Areas that were not
sampled in 2013 (due to access restrictions) in the Middle River Segment, and the IFS study sites
in Geomorphic Reach LR-2 in the Lower River Segment, will be sampled during the next year of
study. Likewise, consideration will be given to adding supplemental sites pending completion of
the habitat mapping (ISR Study 9.9).
6.3. Hydrologic Data Analysis
6.3.1. Mainstem Susitna River
During 2013, the study objectives of the hydrologic data analysis for the Mainstem Susitna River
were met through collection of cross-sectional and hydrologic data to support a variety of
resource studies and development of physical, hydraulic and habitat models. The results from
the water surface elevation and discharge measurement surveys will be used in development of
Version 2 of the Open-water Flow Routing Model. ADCP data collection and analysis
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techniques were adjusted to accommodate specific field and equipment conditions. In all cases,
any modifications of protocols were documented and are available for review (ISR Study 8.5,
Appendix C). In some cases data collection efforts were streamlined and only a water surface
elevation was collected at a given cross-section. However, in these cases, the discharge for these
transects can be interpolated from a nearby discharge measurement.
Analysis of the channel cross-sectional profiles before and after the September 21, 2012 flood
revealed little change in channel structure (Figure 5.3-2 and Figure 5.3-3) suggesting little
bedload transport occurred during the flood. Even when the post-June flood 2013 cross-sections
are included in the comparisons (Figure 5.3-4), the differences in channel profiles are
comparatively small given the overall width of the channels and are unlikely to result in
detectable differences in water surface elevations for a given discharge. Moreover, some
changes were expected between the 2012 and 2013 profiles due to the variability in the 2013
profiles obtained via ADCP measurements that were proximal to but not directly aligned with the
2012 cross-sections. This is exemplified in Figure 6.3-1 and Figure 6.3-2 that display locations
of 2012 profiles at PRM 124.1 and PRM 137.6 respectively, relative to ADCP paths measured in
2013. The corresponding cross-sectional profiles for the two sites are provided in the results
section in Figure 5.3-4 and do show some topographic differences along the profiles between the
different ADCP paths. The differences in channel elevations that are evident between the 2012
and 2013 cross-sectional profiles (Figure 5.3-4) may be due to the June 2013 flood and/or ice
scour that occurred as part of spring-breakup. Again, such differences are comparatively small
relative to overall channel widths and not expected to result in substantial changes in stage-
discharge relationships.
As noted in ISR Study 8.5, Section 5.3, 2-D flow measurements were performed in seven Focus
Areas: FA-104 (Whiskers Slough); FA-113 (Oxbow 1); FA-115 (Slough 6A); FA-128 (Slough
8A); FA-138 (Gold Creek); FA-141 (Indian River); and FA-144 (Slough 21). The 2-D model
flow measurements consisted of closely spaced transects to quantify flow splits between various
channels and sloughs. Results from individual transects were added to obtain streamwise flow
summations throughout each Focus Area. Measurements at the remaining three Focus Areas will
occur during the next year of study.
6.3.2. Tributaries to the Susitna River
Tributary gaging measurements were completed in accordance with the Study Plan and will be
used to help synthesize a long-term period of record. These synthesized records will be used in
the Open-water Flow Routing Model and other riverine-related studies, such as ISR Study 5.6,
Water Quality; ISR Study 6.6, Geomorphology; and ISR Study 7.5, Groundwater. Some data
gaps remain after the 2013 data collection effort. For three sites (the Oshetna River, Deshka
River, and Kosina Creek) only two discharge-staff gage data pairs were collected. At least three
pairs are needed to develop a rating curve. Additional pairs for these locations will be collected
in the next year of study. Companion stage-only gages were installed along the mainstem at the
confluence of Trapper Creek, Birch Creek, and the Deshka River. The local benchmarks at these
three sites were not surveyed, prohibiting stage comparisons between the confluence and the
upstream tributary. These benchmarks will be surveyed during the next year of study to allow
this comparison.
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Preliminary rating curves have been developed for those stations with at least three discharge-
staff gage pairs. However, the hourly data are provisional and not included in this ISR.
Additional data will be collected during the next year of study, which will revise the rating
curves and change the hourly flow estimates. The complete set of rating curves will be provided
in the USR. The current tributary gage data, in addition to the data that will be collected in the
next year of study, will allow development of synthesized tributary records.
6.3.3. Realtime Hydrologic Data and Network
The objectives of the Realtime Hydrologic Data Network were met in 2013 with the continuation
of collection of data at the 13 mainstem recording stations. However, during development of the
Open-water Flow Routing Model it became apparent that all 13 mainstem water-level recording
stations were not needed for calibration purposes. In 2013, the 13 hydrology stations were
prioritized based on whether data from the stations were needed for calibration of the flow
routing model, as well as their utility in other studies (ISR Study 8.5, Section 4.3). The priority
levels of the 13 stations are provided in Table 4.4-2. Several of these sites were not actively
supported in 2013 due to land access conflicts. As a result, some data gaps of water stage and
water temperature exist for the original 13 hydrology stations. Three stations (ESS80, ESS30,
and ESS20) have complete or near-complete datasets. Six stations (ESS65, ESS55, ESS50,
ESS45, ESS40, and ESS35) have partial datasets. Stations ESS70 and ESS60 were removed in
2013, but station ESS60 has data for part of 2013. Stations ESS15 and ESS10 are downstream
of the lower extent of the Open-water Flow Routing Model and were installed to provide basic
hydrology data for LR studies. The ESS data, along with available data from USGS at four
additional sites along the mainstem of the Susitna River, will be used in calibration of Version 2
of the Open-water Flow Routing Model, as well as for modeling in other studies. Given the
availability of complete datasets at seven mainstem locations (three ESS stations and four USGS
stations) it is not anticipated that data gaps at the other ESS stations will hinder study objectives.
6.3.4. Representative Years
Study objectives for Representative Years are being met through the selection of three candidate
representative years for wet, average, and dry conditions during periods of warm or cool PDO
phases. These were selected based on input from multiple resource teams, including sediment
transport, instream flow, and ice processes. These representative years will be presented to and
discussed with the TWG and presented in the Proof of Concept in 2014.
6.3.5. Indicators of Hydrologic Alteration and Environmental Flow Components
The objectives of the IHA analysis will be completed during the next of study once a final set of
hydrologic metrics are selected. As noted in ISR Study 8.5, Section 5.5, these metrics will
include those specific to IHA as well as others that will be developed that will be sensitive to
load-following operations. The selection of metrics will be discussed with the TWG and
finalized as part of the Proof of Concept. Results of the IHA analysis will be included in the
USR.
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6.4. Reservoir Operations and Open-water Flow Routing Modeling
6.4.1. Reservoir Operations Model
The Reservoir Operations Model is on target to meet the study objectives identified in the Study
Plan. The Reservoir Operations Model will be simulated using several different conditions.
Operational scenarios will be developed under the direction of AEA and the working groups.
Once operational scenarios have been identified, they will be simulated using the Reservoir
Operations Model and the output will be provided for use by other studies, in particular the
Open-water Flow Routing Model. Additional detail and discussion will be provided in the USR.
6.4.2. Open-water Flow Routing Model
The Open-water Flow Routing Model developed in 2012 and 2013 (Version 1) met Project
objectives by providing information to support decisions on the downstream extent of Project
effects, helping schedule field studies targeting specific flow and stage conditions, and
identifying 2013 data needs to improve model accuracy. This model will be refined and
improved based on field data collected in 2013 and 2014. A refined version (Version 2) of the
Open-water Flow Routing Model is currently being developed incorporating additional data
collected in 2013; Version 2 will be available in 2014. Hydrologic data include additional
transect cross-sectional profiles, additional discharge/water level data pairs, and hourly stage
data from the main channel and tributary location. Hydrologic data will continue to be collected
in 2014 and a final Open-water Flow Routing Model will be developed and distributed for
review during the last year of study. Major changes in the mainstem Open-water Flow Routing
Model findings are not anticipated as a result of the additional data collected. However, the
additional data and model refinements will improve the accuracy of hourly flow and stage
simulations at complex channel features and within instream flow sampling and modeling areas.
Version 2 of this model, which is under development, will incorporate the following additional
information:
• Tributary drainage areas will be delineated, and tributary flow measurements will be
made. These will be used to help estimate lateral accretion flows.
• Cross-sections will be extended up to higher elevations using LiDAR data and ground-
based RTK-GPS surveys.
• Additional pairs of flow/water surface elevations will be incorporated, especially in the
Lower Susitna River. These data will be used to help improve the steady-state
calibration.
• Additional cross-sections from the geomorphology study will be incorporated in the
model.
• Diurnal glacial melt fluctuations will be incorporated into the summer hydrographs.
Several other studies included in this project have also developed flow routing models to meet
their specific needs. These include Reservoir Operations (ISR Study 8.5, Section 4.4), Ice
Processes (River1D) (ISR Study 7.6), Water Quality (EFDC) (ISR Study 5.6), and Fluvial
Geomorphology (ISR Study 6.6). The Reservoir Operations Model has a river component that is
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used to incorporate minimum instream flow conditions into the simulation of the With-Project
scenario. The water quality model has a different time step and utilizes different transects. The
ice processes modeling utilizes the Open-water Flow Routing Model to link with an under ice
model (River1D). The sediment transport modeling uses input from the Open-water Flow
Routing Model and also includes a steady-state 2-D hydraulic model at Focus Areas. Each of
these models is being developed for specific purposes and where appropriate, cross-comparisons
of model outputs will be made for QA/QC purposes. As noted, the Open-water Flow Routing
Model will continue to be used to evaluate stage conditions in the Susitna River With and
Without the Project and will also provide inputs to certain models.
6.5. Habitat Suitability Criteria Development
The overall goal of the HSC study is to develop site-specific HSC/HSI curves for various priority
species and life stages of fish for use in assessing the effects of the proposed Project on the
quantity and quality of fish habitats through the use of aquatic habitat models (ISR Study 8.5,
Section 5.6 and 6.6). At this time, data collection efforts are on schedule to provide sufficient
microhabitat use and availability data to develop site-specific HSC/HSI preference curves for
each of the high and moderate priority species. In addition, HSC/HSI data have been and will
continue to be collected that will in combination with other studies, be used for evaluating
Project effects on other ecologically important factors such as groundwater upwelling,
intergravel temperature and dissolved oxygen.
The following section provides an overview of the key activities completed during the 2013
HSC/HSI curve development.
6.5.1. Selection of Priority Species and Life Stage
A priority ranking of the 19 fish species to be considered for site-specific HSC curve
development was developed in collaboration with the TWG in Q2 2013. The high and moderate
ranked species are generally considered the most sensitive to habitat loss through manipulation
of flows in the Susitna River. Although no direct effort was made to collect site-specific
microhabitat use information for low-priority ranked species during the 2013 effort, incidental
observations of these species were noted. Microhabitat use observations were collected for all
seven of the high priority species and three of the five moderate priority species (Table 5.5-1).
For the two moderate priority species (Dolly Varden and eulachon) for which no HSC
measurements were collected in 2013, the next year sampling effort will target areas of known
use (upstream of Devils Canyon and downstream of Three Rivers Confluence) to improve the
chance of detection.
6.5.2. HSC/HSI Study Site Selection
A substantial effort was made in 2013 directed toward collection of HSC/HSI data. However,
issues related to access and flow caused delays in habitat mapping that precluded sampling in the
Lower River Segment and upper portion of the Middle River Segment of the Susitna River. Site
access restrictions for the upstream-most Focus Areas (FA-151 [Portage Creek], FA-173
[Stephan Lake Complex], and FA-184 [Watana Dam]) in the Middle River Segment prevented
these areas from being sampled in 2013. For the seven Focus Areas that were sampled in 2013,
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68 sampling segments were selected within which data were collected in accordance with the
Study Plan (ISR Study 8.5, Section 5.5).
6.5.3. Collection of Site-Specific Microhabitat Utilization and Availability Data
Field data collection in 2013 was completed during 210 unique sampling events and included
1,443 measurements of microhabitat use and 3,297 habitat availability measurements in
mainstem and off-channel habitats in the Middle River Segment of the Susitna River. Collection
of both microhabitat use and availability data will allow for development of site-specific
HSC/HSI curves for most if not all of the moderate and high priority species. Of the eleven
species (round and humpback whitefish observations combined) for which microhabitat use
measurements were collected, seven species had more than 100 unique observations.
6.5.4. Habitat Utilization Frequency Histograms
Frequency distributions (i.e., histograms) were generated for mean velocity, depth, and substrate
use for each species. Frequency bin widths of 0.2 were 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 sufficient field observations were
recorded. For a subset of HSC frequency distribution plots, data from both the 2013 and 2012
HSC surveys were plotted together to see if patterns of microhabitat use were similar.
6.5.5. Winter Studies
The 2012-2013 winter pilot study was conducted at two Focus Areas, FA-104 (Whiskers Slough)
and FA-128 (Slough 8A), that supported salmon spawning in 2012 and contained a diversity of
main channel and off-channel habitats. The close proximity of FA-104 (Whiskers Slough) to
Talkeetna allowed greater time allotment on field data collection relative to logistic support
demands (e.g., remote camp construction and travel). Winter studies data collection during the
next winter season will be conducted at additional sites as described in ISR Study 8.5, Section
7.5.
6.5.6. Stranding and Trapping
There were no formal stranding and trapping surveys completed in 2013. AEA will discuss the
need for stranding and trapping surveys with the resource agencies. If stranding and trapping
surveys are not needed, ramping criteria developed in Washington State (Hunter 1992) will be
proposed as fallback criteria during effects analyses.
6.5.7. River Productivity
AEA implemented data collection methods for developing HSC/HSI models for invertebrates as
described in the River Productivity Study Plan with no variances. However, laboratory results
from a majority of the samples collected in 2013 were not available for inclusion in the ISR.
These results are scheduled to be available in 2014, at which time HSC/HSI model development
will begin. Initial models will be presented as part of the Proof of Concept discussions in 2014.
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6.5.8. Interim Periodicity Tables
Detailed interim periodicity tables were developed for all twelve of the high and moderate
priority ranked species. In many cases, distinctions were made between differences in timing of
habitat use within a river segment and between river segments. There were no variances from
the Study Plan. The interim periodicity tables will be reviewed for possible revisions as data
from other fisheries studies become available. Final species and life stage periodicity will be
used as part of the Project effects analysis.
6.5.9. Biological Cues
The Biological Cues analysis identified several weak to moderate correlations between
productivity or run timing metrics and hydrologic indices for the Taku and Stikine rivers. For
the Taku River, observed relationships were as follows:
• There are more returns per spawner when there are high winter flows combined with no
large summer flow decreases that could result in trapping events.
• There are more smolts per spawner when the summer low flow is moderate or relatively
high.
• The duration of the Chinook run is longer when flows are more variable.
For the Stikine River, observed relationships were as follows:
• Total returns tend to be higher when the winter minimum flow is higher.
• Total returns tend to be lower when PDO is higher during early ocean rearing.
• There tend to be fewer smolts per spawner when there are large flow decreases during the
spawning period.
• The duration of the Chinook run is longer when flows are more variable.
• The median date of the run is earlier when there are late high flows.
In general, significant correlations were inconsistent for similar indices analyzed from the Taku
River and Stikine River datasets. Thus, applying the results from the Taku or Stikine rivers to
other Chinook salmon populations, such as in the Susitna River, could be erroneous and should
be done with caution.
6.5.10. Relationship Between Microhabitat Use and Fish Abundance
In the Study Plan Determination (FERC 2013b), FERC recommended that the following
additional variables be compared to fish distribution and abundance: surface flow and
groundwater exchange fluxes, dissolved oxygen (intergravel and surface water), macronutrients,
temperature (intergravel and surface water), pH, dissolved organic carbon, alkalinity, and
chlorophyll-a. If strong relationships are evident between fish habitat use and any of these
variables, FERC suggested that additional HSC preference curves may need to be developed for
the various species and life stages. At this time, most of the data necessary to complete this
analysis are not available. It is anticipated that most if not all of the data will be available from
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the various studies in 2014 and that preliminary results of the analysis will be available for
presentation as part of the Proof of Concept. This will provide sufficient time to adjust the
HSC/HSI data collection efforts to add any variables found to exhibit relationships with fish.
6.6. Habitat-Specific Model Development
During 2013, the objectives of developing Habitat-Specific Models were met via the selection of
hydraulic and habitat models and collection of data to support those models. Data analysis and
model calibrations were likewise initiated in 2013 and preliminary model results presented to the
TWG during the IFS-TT Riverine Modelers Meeting on November 13-15, 2013. Model
development is on schedule and a more complete presentation of preliminary results will be
provided during Proof of Concept discussions in 2014.
6.6.1. Habitat Model Selection
The selection of habitat models for both the Middle River Segment and Lower River Segment of
the Susitna River was successfully completed in 2013. For the Middle River Segment, 2-D
hydraulic models were selected for application within each Focus Area, to be coupled with
appropriate HSC/HSI Supplemental analysis within the Middle River Segment may also be
provided via 1-D hydraulic and PHABSIM analysis of data collected at selected cross-sections.
For the Lower River Segment, a 1-D hydraulic model based PHABSIM analysis was selected.
6.6.2. Field Coordination and Collection of Physical and Hydraulic Data
6.6.2.1. Boundary Conditions
As noted in ISR Study 8.5, Section 5.6., AEA identified the upstream and downstream
boundaries as well as the lateral extents of the Focus Areas within the Middle River Segment for
the hydraulic and bed evolution modeling. Considerations included encompassing potential
inflow and outflow points to preserve the mass balance and minimize difficulties and
assumptions associated with inflow points.
6.6.2.2. 2-D Modeling
Data collection for 2-D habitat modeling was completed in seven Focus Areas in 2013. Data
collection for the remaining three Middle River Segment Focus Areas is planned for the next
year of study prior to the USR. Data for the seven Focus Areas between PRM 104 and PRM 145
in 2013 (ISR Study 6.6 and ISR Study 8.5, Section 4.4) were primarily collected by survey crews
for the 2-D hydraulic models. Field crews collected substrate and cover data at these same seven
Focus Areas in 2013. The survey data included topography, bathymetry, stage-discharge
measurements and velocity profiles. Evaluation of the adequacy of the 2013 field data to support
modeling efforts will be conducted during model calibration. If data gaps or additional data
needs are identified, the information can be collected prior to the USR. Data collection for the
remaining three Focus Areas is planned for the next year of study prior to the USR.
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6.6.2.3. 1-D Single Transect Modeling
The collection of field data for the development of hydraulic models for the Lower River
Segment sites in 2013 was based on an approach to collect channel geometry, water surface
elevation and velocity profile data at a single discharge with water surface elevations surveyed at
two additional flow conditions. The 2013 study effort concentrated on sites located in and near
Trapper Creek and within Birch Creek Slough, as well as the main channel Susitna River near
PRM 97. During the next year of study, sites will be established and measured within Sheep
Creek Slough, Caswell Creek, and within main channel and side channel areas of the Susitna
River near PRM 66 through 68. The single discharge approach requires an assumption of a
stable bed profile amongst all of the field surveys, which may be difficult to uphold for the main
channel and bar island complex habitats areas where within year channel changes were observed
at several locations during the 2013 field surveys. Evaluation of the adequacy of the 2013 field
data to support modeling efforts will be conducted during model calibration. If data gaps or
additional data needs are identified, the information can be collected during the next year of
study.
6.6.3. Model Development
6.6.3.1. 2-D Modeling
Calibration of the 2-D hydraulic models for the Middle River Segment Focus Areas was initiated
but not completed in 2013. This schedule is consistent with the Study Plan that identified
hydraulic model calibration would occur after the ISR but before the USR. AEA completed and
presented preliminary 2-D modeling results of one Focus Area (FA-104 [Whiskers Slough]) at
the November 13-15, 2013 IFS-TT Riverine Modelers Meeting. That analysis was based on the
SRH – 2D model, which is one of two models (the second model is River2D) being evaluated for
use in the geomorphology studies (ISR Study 6.6).
AEA also developed the conceptual framework for the 2-D habitat analysis in 2013 that includes
a tabular and spatial analysis framework. That framework was presented and discussed at the
November 13-15, 2013 IFS-TT Riverine Modelers meeting. The framework uses both a VB
model and GIS tool; the VB model automates some of the analysis sequence and can be applied
to all species/life stages over the extent of the 2-D model domain; the GIS tool can be applied to
either the entire model domain or selected smaller spatial areas within the model domain. The
VB model and GIS are necessary since the SRH-2D model does not include a direct simulation
of habitat and both SRH-2D and River2D do not include a means to analyze areas smaller than
the entire model domain. River2D contains a habitat simulation component but only for the use
of HSC data with physical parameters of depth, velocity or channel index paired with a
suitability index. River2D cannot directly compute habitat area from an HSC equation. The VB
model and GIS tool can calculate habitat use from an HSC equation which can then be applied
within the 2D-hydraulic model(s).
6.6.3.2. 1-D Single Transect Modeling
Results of the initial calibration runs of the HEC-RAS model indicate it is the appropriate model
for meeting the study objectives of providing water level predictions over the range of simulated
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discharges required to assess project impacts. Final calibrations will be made in 2014, with
results presented during the Proof of Concept discussions. Those calibrations will rely on the
next version (Version 2) of the Open-water Flow Routing Model (ISR Study 8.5, Section 5.3)
Version 2 of the Open-water Flow Routing Model update will include additional transects in the
vicinity of the fish habitat sites that can be used for set-up and calibration.
6.6.4. Fish Habitat Evaluation Metrics
The development of fish habitat evaluation metrics was initiated in 2013 and is on schedule for
completion. These metrics are dependent on inputs from a variety of other studies and models
including the 2-D and 1-D hydraulic models; HSC/HSI studies (ISR Study 8.5, Section 5.5 and
6.5); Geomorphology models (ISR Study 6.6); Ice processes studies and models (ISR Study 7.6),
Groundwater analysis (ISR Study 7.5) and Water quality models (ISR Study 5.6).
6.6.4.1. Weighted Useable Area
Weighted useable area metrics and flow relationships will be generated using select priority
species and life stages of fish and macroinvertebrates identified for the Middle and Lower River
segments and in a basic time series analysis for assessing differences among existing and Project
flow scenarios. Final HSC/HSI data are not yet available. Weighted useable area curves may
also be generated for certain species and life stages at selected transects within the Middle River
Segment (ISR Study 8.5, Section 5.6).
6.6.4.2. Effective Spawning / Incubation Habitat Analyses
An overview of the general approach for and a specific example of the Effective
Spawning/Incubation Habitat Analyses was presented and discussed during the November 13-15,
2013 IFS TT Riverine Modelers Meeting on November 13-15, 2013. This approach will be
further refined in 2014 and presented in detail in the Proof of Concept.
6.6.4.3. Varial Zone Modeling
Varial zone modeling of the Focus Areas will begin when calibrated 2-D hydraulic models are
completed. Varial zone modeling will use the 2-D hydraulic model output to determine water
surface elevation at each simulation flow throughout each Focus Area.
6.6.4.4. Breaching Flows and Habitat Connectivity
Breaching flow analysis will be conducted during the next year of study in conjunction with
Focus Area hydraulic modeling. The breaching flow analysis will require iterative hydraulic
model runs to determine the breaching flows in each Focus Area. This will be accomplished by
closely coordinating with the 2-D hydraulic modelers on the simulation flows needed to
determine breaching.
An assessment of breaching flows, fish barriers and connectivity within Lower River Segment
study sites was not conducted in 2013 and will be completed during the next year of study. The
approach being proposed is to apply simulated cross-sectional averaged depth and velocity
conditions at each of the lower river fish habitat transects as an indicator of changes to
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breaching, fish passage and connectivity in terms of frequency, timing and duration based on
specific depth and velocity criteria to be developed as part of ISR Study 9.12.
6.7. Temporal and Spatial Habitat Analyses
Several general approaches for completing the Fish and Aquatics IFS temporal and spatial
habitat analyses were discussed at the November 13-15, 2013 IFS-TT Riverine Modelers
Meeting on. These approaches will be further discussed with the TWG in 2014 and finalized and
presented during the Proof of Concept.
6.8. Instream Flow Study Integration
Although most work on study integration will not take place until the next year of study, AEA
initiated the process of building a DSS framework in 2013. Based on an evaluation of several
approaches and discussion with the TWG as part of the IFS-TT Riverine Modelers Meeting of
November 13-15, 2013, AEA decided to use the matrix method as the basis for decision-making,
with the possible consideration of addressing uncertainties in a decision analysis framework.
AEA does not intend to produce stand-alone software for the DSS. Work on the DSS will
continue in 2014.
7. COMPLETING THE STUDY
[As explained in the cover letter to this draft ISR, AEA’s plan for completing this study will be
included in the final ISR filed with FERC on June 3, 2014.]
8. LITERATURE CITED
Aaserude, R.G., J. Thiele, and D. Trudgen. 1985. Characterization of aquatic habitats in the
Talkeetna-to-Devil Canyon segment of the Susitna River, Alaska. Final report by Trihey
and Associates and Arctic Environmental Information and Data Center to Alaska Power
Authority. 144 pp. APA Document 2919.
ADF&G (Alaska Department of Fish and Game). 1983. Volume 4. Aquatic habitat and
instream flow studies, 1982. Susitna Hydro Aquatic Studies, Phase II Basic Data Report.
Prepared for Alaska Power Authority. Alaska Department of Fish and Game, Anchorage,
Alaska. APA Document 585.
AEA (Alaska Energy Authority). 2011. Pre-application Document (PAD): Susitna-Watana
Hydroelectric Project FERC Project No. 14241. December 2011. Prepared for the
Federal Energy Regulatory Commission, Washington, DC.
AEA (Alaska Energy Authority). 2012. Revised Study Plan: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/study-plan.
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AEA (Alaska Energy Authority). 2013. Meeting Notes: Riverine Modelers Technical Team
meeting on November 13, 14, and 15, 2013. Susitna-Watana Hydroelectric Project,
FERC No. P-14241. http://www.susitna-watanahydro.org/meetings/past-meetings/
Alexander, C.A.D., C.N. Peters, D.R. Marmorek, and P. Higgins. 2006. A decision analysis of
flow management experiments for Columbia River mountain whitefish (Prosopium
williamsoni) management. Can. J. Fish Aquat. Sci. 63: 1142–1156.
Ashton, W.W., and E.W. Trihey. 1985. Assessment of Access by Spawning Salmon into
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9. TABLES
INITIAL STUDY REPORT FISH AND AQUATICS INSTREAM FLOW STUDY (8.5)
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Table 4.2-1. Geomorphic reach designations for the Upper River (UR) Segment, Middle River (MR)
Segment, and Lower River (LR) Segment of the Susitna River.
Reach
Designation
Reach Breaks (PRM)
Reach Classification
Slope
(ft/mi) Lateral Constraints Upstream
Down-
stream
Upper Susitna River Segment (UR)
UR-1 261.3 248.6 SC2 NA Quaternary Basin Fill
UR-2 248.6 234.5 SC1 NA Quaternary Basin Fill
UR-3 234.5 224.9 SC1 NA Quaternary Basin Fill
UR-4 224.9 208.1 SC2 NA Granodiorite
UR-5 208.1 203.4 SC1 NA Quaternary Basin Fill
UR-6 203.4 187.1 SC2 NA Quaternary Basin Fill
Middle Susitna River Segment (MR)
MR-1 187.1 184.6 SC2 9 Tertiary-Cretaceous Gneiss
MR2 184.6 169.6 SC2 10 Cretaceous Kahiltna Flysch Tertiary-
Cretaceous Gneiss
MR-3 169.6 166.1 SC2 17 Paleocene Granites
MR-4 166.1 153.9 SC1 30 Paleocene Granites
MR-5 153.9 148.4 SC2 12 Cretaceous Kahiltna Flysch
MR-6 148.4 122.7 SC3 10
Cretaceous Kahiltna Flysch with
undifferentiated Upper Pleistocene
moraines, kames, lacustrine deposits
MR-7 122.7 107.8 SC2 8
Cretaceous Kahiltna Flysch with
undifferentiated Upper Pleistocene
moraines, kames, lacustrine deposits
MR-8 107.8 102.4
MC1/SC3
(Reach is a transition from SC3
to MC1 as the Three Rivers
Confluence is approached)
8 Upper Pleistocene moraines, outwash
and Holocene Alluvial Terrace deposits
Lower Susitna River Segment (LR)
LR-1 102.4 87.9 MC1 5 Upper Pleistocene Outwash, Moraine
and Lacustrine deposits
LR-2 87.9 65.6 MC2/MC3 5 Upper Pleistocene Outwash, Moraine
and Lacustrine deposits
LR-3 65.6 44.6 MC3 4 Upper Pleistocene Glaciolacustrine
deposits
LR-4 44.6 32.3 MC2 2 Upper Pleistocene Glaciolacustrine
deposits
LR-5 32.3 23.5 SC2 2
Upper Pleistocene Glaciolacustrine and
Moraine deposits and Late Cretaceous
granodiorite
LR-6 23.5 3.3 MC4 1.4 Upper Pleistocene Glaciolacustrine and
Holocene Estuarine deposits
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Table 4.2-2. Nested and tiered habitat mapping units, categories, and definitions.
Level Unit Grouping Category Definitions
1
Major
Hydrologic
Segment
Segments
Upper,
Middle, Lower
River
Upper River – PRM –187.1 – 261.3 (habitat mapping extended up to mainstem PRM 235.1 and included the Oshetna River.
Middle River – PRM –102.4 – 187.1
Lower River – PRM 0 – 102.4
2 Geomorphic
Reach
Upper River
Segment 6 reaches
Geomorphic reaches that uniquely divide the Major Hydrologic Segments based on geomorphic characteristics. Middle River
Segment 8 reaches
Lower River
Segment1 6 reaches
3 Macrohabitat
Mainstem
Habitat
Main Channel Single dominant main channel.
Split Main
Channel Two dominant channels.
Multiple Split
Main Channel Three or more distributed dominant channels.
Side Channel Channel that is turbid and connected to the active main channel but represents non-dominant proportion of flow1
Tributary
Mouth
Clear water areas that exist where tributaries flow into Susitna River main channel or side channel habitats (upstream Tributary
habitat will be mapped as a separate effort).
Off-Channel
Habitat2
Side Slough Overflow channel contained in the floodplain, but disconnected from the main channel. Surveyed when flows < 18,000 cfs or at
higher flows if there was no evidence of breaching. Had clear water.3,4
Upland
Slough Similar to a side slough, but contains a vegetated bar at the head that is rarely overtopped by mainstem flow. Has clear water.1.
Tributary
Habitat
Single
Channel Single dominant channel
Split Channel Two dominant channels
Channel
complex Three or more distributed dominant channels
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Level Unit Grouping Category Definitions
4 Mesohabitat
Fast water
Rapid
Swift, turbulent flow including small chutes and some hydraulic jumps swirling around boulders. Exposed substrate composed of
individual boulders, boulder clusters, and partial bars. Lower gradient and less dense concentration of boulders and white water
than Cascade. Moderate gradient; usually 2.0-4.0 percent slope.2
Riffle A fast water habitat with turbulent, shallow flow over submerged or partially submerged gravel and cobble substrates. Generally
broad, uniform cross-section. Low gradient; usually 0.5-2.0 percent slope.2
Run
A habitat area with minimal surface turbulence over or around protruding boulders with generally uniform depth that is generally
greater than the maximum substrate size.2 Velocities are on border of fast and slow water. Gradients are approximately 0.5
percent to less than 2 percent. Generally deeper than riffles with few major flow obstructions and low habitat complexity.2
Glide
An area with generally uniform depth and flow with no surface turbulence. Low gradient; 0-1 percent slope. Glides may have some
small scour areas but are distinguished from pools by their overall homogeneity and lack of structure. Generally deeper than riffles
with few major flow obstructions and low habitat complexity.2
Slow
Water Pool Slow water habitat with minimal turbulence and deeper due to a strong hydraulic control.
Special
Habitat
Feature
Clearwater
Plume
Discharge from a tributary that forms a pronounced area of clearwater, in contrast to the turbid water of the main channel, along the
main channel shoreline. The length, breadth, and depth of the clearwater plume depend on the relative discharge between the
tributary and the main channel, relative turbidity, and on mixing conditions along the shoreline. A clear water plume will be mapped
as if it were a separate mesohabitat type.
Backwater Found along channel margins and generally within the influence of the active main channel with no independent source of inflow.
Water is not clear. A backwater will be mapped as if it were a separate mesohabitat type.
Beaver
Complex Complex ponded water body created by beaver dams. A beaver dam will be mapped as if it were a separate mesohabitat type.
Tributary
Mesohabitat Tributary mesohabitats were typed using the classification system described in Table 1.1-2
Notes:
1 For the purposes of this ISR, classification of the Lower River segment stopped at Level 2. A classification system for the Lower River segment is still in
development pending determination of Project effects in the Lower River.
2 All habitat within this designation received an additional designation of whether water was clear or turbid within the database.
3 The terms Side Channel, Slough, and Upland Slough are similar but not necessarily synonymous with the terms for macrohabitat type as applied by Trihey
(1982) and ADF&G (1983a).
4 All slough habitat will have an associated area created during the mapping process to better classify size.
5 Adapted from Moore et al. 2006.
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Table 4.2-3. Locations, descriptions and selection rationale of 10 Final Focus Areas identified 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 Upstream Downstream Main Channel, Single Main Channel, Split Main Channel, Multiple Split Side Channel Side Slough Upland Slough Tributary Spawning Rearing IFG DIHAB RJHAB FA-
184
Watana
Dam
Area approximately
1.4 miles downstream
of dam site
MR-1 185.7 184.7 1.0 X X N/A N/A N/A N/A N/A FA-184 length comprises 40% of MR-1 reach length (2.5 miles long) and
contains split main channel and side channel habitat present in this reach.
FA-
173
Stephan
Lake
Complex
Wide channel near
Stephan Lake with
complex of side
channels
MR-2 175.4 173.6 1.8 X X X X X N/A N/A N/A N/A N/A
FA-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 miles long and channel is generally straight with few side
channels and moderate floodplain width (2-3 main channel widths).
FA-
151
Portage
Creek
Single channel area at
Portage Creek
confluence
MR-5 152.3 151.8 0.5 X X X X
FA-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.
FA-
144 Slough 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
FA-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.
FA-
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
FA-141 includes the Indian River confluence and a range of main channel
and off-channel habitats. High fish use of the Indian River mouth has been
documented and DIHAB modeling was performed in main channel areas in
the 1980s. Studies in the 1980s did not document high fish use of lateral
habitats on the right bank upstream of the Indian River confluence.
FA-
138
Gold
Creek
Channel complex
including Side
Channel 11 and
Slough 11
MR-6 140 138.5 1.5 X X X X X X X X
The FA-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 FA-138 is characteristic of Reach MR-6.
IFG modeling was performed in side channel habitats in the 1980s.
FA-
128 Slough 8A
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
FA-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.
FA-
115 Slough 6A
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
FA-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.
FA-
113 Oxbow 1 Oxbow 1 Complex and
Upstream Area MR-7 115.3 113.6 1.7 X X X X X X X
FA-113 was added in response to Agency comments that important fish
habitat area was underrepresented in MR-7. Oxbow I is an important chum
salmon rearing area.
FA-
104
Whiskers
Slough
Whiskers Slough
Complex MR-8 106 104.8 1.2 X X X X X X X X X X
FA-104 contains diverse range of habitat, which is characteristic of the
braided, unconfined Reach MR-8. FA-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 4.2-4. Summary of Potential Effects of With-Project Flows on Tributaries of the Lower Susitna River
from 1980s studies, and tributary mouths proposed for modeling in 2013 (indicated by highlighting) (1980s
summary adapted from Ashton and Trihey (1985)).
Tributary
Project River
Mile
(approx.)
Geomorphic
Reach
Location of Tributary Mouth in
Effects of With-Project Flows on
Fish Access into Tributaries at 21,000 cfs (USGS Sunshine Gage 15292780)
Reduction in Backwater Area during June/July
Side
Channel
Main
Channel
Potential
Passage
Problem
No
Passage
Problem
Moderate
Change
Slight
Change
Trapper Cr. 95.4 LR-1 X X X
Birch Cr. 93.3 LR-1 X X X
Sunshine Cr. 88 LR-1 X X X
Rabideaux Cr. 87.2 LR-2 --- --- X X
Montana Cr. 81 LR-2 X X X
Goose Cr. 76.8 LR-2 X X X
Sheep Cr. 71.7 LR-2 X X X
Caswell Cr. 67.3 LR-2 X X X
Kashwitna R. 64.7 LR-3 X X X
Little Willow Cr. 54.5 LR-3 X X X
Willow Cr. 52.1 LR-3 X X X
Deshka R. 44.9 LR-3 X X X
Alexander Cr. 13.7 LR-6 X X X
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Table 4.3-1. Susitna Real-Time Reporting Network Stations.
Site Name Short Name Parameters
Upper Segment AEA Gaging Stations
15291500 Susitna River Near Cantwell ESS80 discharge, water level, water and air temperature, camera
Middle Segment AEA Gaging Stations
Susitna River Below Deadman Creek ESS70 discharge, water level, water and air temperature, camera
Susitna River Below Fog Creek ESS65 discharge, water level, water and air temperature, camera
Susitna River Above Devil Creek ESS60 discharge, water level, water and air temperature, camera
Susitna River Below Portage Creek ESS55 discharge, water level, water and air temperature, camera
Susitna River at Curry ESS50 discharge, water level, water and air temperature, camera
Susitna River Below Lane Creek ESS45 discharge, water level, water and air temperature, camera
Susitna River Above Whiskers Creek ESS40 discharge, water level, water and air temperature, camera
Lower Segment AEA Gaging Stations
Susitna River at Chulitna River ESS35 discharge, water level, water and air temperature, camera
Susitna River Below Twister Creek ESS30 discharge, water level, water and air temperature, camera
15294350 Susitna River at Susitna Station ESS20 discharge, water level, water and air temperature, camera
Susitna River Near Dinglishna Hill ESS15 water level, water and air temperature, camera
Susitna River Below Flat Horn Lake ESS10 water level, water and air temperature, camera
Repeater Stations
Mount Susitna Near Granite Creek ESR1 air temperature
Repeater, East of ESM1, First Potential
Site ESR2 air temperature
Repeater, Dam Site to Glacial Repeater ESR3 air temperature
Curry Ridge near McKenzie Creek
Repeater ESR4 air temperature
Curry Pt. To State Park Repeater ESR5 air temperature, camera
State Park over Devils Canyon Repeater ESR6 air temperature, camera
Portage Creek Repeater ESR7 air temperature
ESR2 to ESS80, ESM2 link ESR8 air temperature
Base Stations
Talkeetna Base Station ESB2 N/A
Notes:
1 ESS = AEA Susitna River Surface-Water Station.
2 ESR = AEA Susitna River Repeater Station
3 ESB = AEA Susitna River Base Station
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Table 4.3-2. Summary of gaging stations established on Susitna River in 2012.
Gaging Station Project River Mile Segment
Susitna River near Cantwell (ESS80) 225.0 Upper Susitna River
Susitna River below Deadman Creek (ESS70) 187.1 Middle Susitna River (above Devils
Canyon) Susitna River below Fog Creek (ESS65) 176.5
Susitna River above Devil Creek (ESS60) 168.1
Susitna River above Portage Creek (ESS55) 152.2
Middle Susitna River (below Devils
Canyon)
Susitna River at Curry (ESS50) 124.1
Susitna River below Lane Creek (ESS45) 116.6
Susitna River above Whiskers Creek (ESS40) 107.2
Susitna River at Chulitna River (ESS35) 102.1
Susitna River below Twister Creek (ESS30) 98.4
Lower Susitna River Susitna River at Susitna Station (ESS20) 29.9
Susitna River near Dinglishna Hill (ESS15) 24.7
Susitna River below Flat Horn Lake (ESS10) 17.4
Notes:
1 ESS = AEA Susitna River Surface-Water Station.
Table 4.3-3. Tributary gaging site information.
Tributary Name Susitna PRM Gage Site Type Elevation (ft) Latitude Longitude
Oshetna River 235.1 Continuous 2173 62.628520 -147.369830
Kosina Creek 209.1 Continuous with barologger 1911 62.755970 -147.955150
Unnamed Tributary 144.6 144.6 Spot 750 62.803980 -149.591350
Indian River 142.1 Continuous 775 62.800826 -149.664417
Skull Creek 128.1 Continuous with barologger 599 62.657530 -149.932540
Gash Creek 115 Continuous 460 62.504288 -150.104018
Slash Creek 114.9 Spot 452 62.503202 -150.103737
Unnamed Tributary 113.7 113.7 Continuous 455 62.486316 -150.093785
Whiskers Creek 105.1 Continuous with barologger 370 62.378096 -150.170806
Trapper Creek 95.4 Continuous 310 62.257540 -150.172762
Susitna River at Trapper Creek 95.4 Continuous stage only 306 62.253622 -150.168375
Birch Creek 93.3 Continuous 307 62.250468 -150.089622
Susitna River at Birch Creek
Slough
92.6 Continuous stage only 291 62.223373 -150.116821
Deshka River 44.9 Continuous with barologger 83 61.754230 -150.328540
Susitna River at Deshka River 44.9 Continuous stage only 78 61.696491 -150.313659
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Table 4.3-4. Period of record of flows measured by the USGS on the Susitna River.
Gage Number Site Project River Mile Drainage Area (mi2) Latitude Longitude
Elevation (ft, NGVD 29)
Period of Record of Measured Flows
15291000 Susitna River
near Denali 291.8 950 63.10389 147.51583 2,440
27 years:
1957-1976;
1978-1986
15291500 Susitna River
near Cantwell 225.0 4,140 62.69861 147.54500 1,900
17 years:
1961-1972;
1980-1986
15292000 Susitna River at
Gold Creek 140.0 6,160 62.76778 149.69111 677
57 years:
1949-1996;
2001-2011
15292780 Susitna River at
Sunshine 87.9 11,100 62.17833 150.17500 270 5 years:
1981-1986
15294350 Susitna River at
Susitna Station 29.9 19,400 61.54472 150.51250 40 19 years:
1974-1993
Table 4.3-5. Period of record of flows measured by the USGS on tributaries of the Susitna River.
Gage Number Site
Susitna River PRM at Confluence
Drainage Area (mi2) Latitude Longitude
Elevation (ft, NGVD 29) Period of Record of Measured Flows
15291200 Maclaren River
near Paxson 261.1 280 63.11944 146.52917 2,866 28 years:
1958-1986
15292400 Chulitna River
near Talkeetna 102.4 2,570 62.55861 150.23389 520
20 years:
1958-1972;
1980-1986
15292700 Talkeetna River
near Talkeetna 100.3 1,996 62.34694 150.01694 400 47 years:
1964-2011
15294005 Willow Creek
Near Willow 52.1 166 61.78083 149.88444 350
25 years:
1978-1993;
2001-2011
15294345 Yentna River near
Susitna Station 31.4 6,180 61.69861 150.65056 80 6 years: 1980-1986
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Table 4.4-1. Comparison of the content contained in the three versions of the hydraulic routing model.
Model Component Version 1 Version 2 Version 3
Extent PRM 80-187.2 PRM 29.9-187.2 PRM 29.9-187.2
Number of Cross-sections 88 167 212
WSE/Q Measurements 120 419 486
Accretion Hourly Hourly Hourly
Diurnal Fluctuations None Partial Complete
Floodplain coverage None None Extended using LiDAR
Calibration/Validation Data 5 gages
15291700
15292000
15292780
15292400
15292700
7 gages
15291700
15292000
15292780
15294350
15292400
15292700
15294345
7 gages
15291700
15292000
15292780
15294350
15292400
15292700
15294345
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Table 4.4-2. Summary of 2012-2013 surface water data collected at selected ESS stations in the Susitna River. ESS = AEASusitnaSurface water
measurements.
Station PRM
Water Level Record
Available
Water Temperature
Record Available
Air Temperature Record
Available
Camera
Images
Land Access
Granted Studies Using Data
ESS80 225.0 Complete Complete Complete Yes Yes
Engineering, Upper Basin DGGS,
Glacier and Runoff Changes, Reservoir
Modeling
ESS70 187.1 Aug 2012 – Oct 2012 Aug 2012 – Oct 2012 Complete Yes No
IFS, Ice Processes, Geomorphology,
Water quality, Engineering, Upper Basin
DGGS, Glacier and Runoff Changes,
Groundwater
ESS65 176.5 Oct 2012,
Jan – May 2013
Oct 2012,
Jan – May 2013 Complete Yes No IFS, Ice Processes, Geomorphology,
Water Quality
ESS60 168.1 Oct 2012 – May 2013 Oct 2012 – May 2013 Complete Yes No IFS, Ice Processes, Geomorphology,
Water Quality
ESS55 152.2 Aug 2012 – May 2013 Aug 2012 – May 2013 Complete Yes No IFS, Ice Processes, Geomorphology,
Water Quality, Groundwater
ESS50 124.1 Aug – Oct 2012,
Aug – Dec 2013
Aug – Oct 2012,
Aug – Dec 2013 Complete Yes Yes IFS, Ice Processes, Geomorphology,
Water Quality, Groundwater
ESS45 116.6 Aug 2012 – May 2013,
Aug – Dec 2013
Aug 2012 – May 2013,
Aug – Dec 2013 Complete Yes Yes IFS, Ice Processes, Geomorphology,
Water Quality, Groundwater
ESS40 107.2 Aug 2012 – May 2013,
Aug – Dec 2013
Aug 2012 – May 2013,
Aug-Dec 2013 Complete Yes Yes IFS, Ice Processes, Geomorphology,
Water Quality, Groundwater
ESS35 102.1 Aug 2012 – May 2013 Aug 2012 – May 2013 Complete Yes Yes IFS, Ice Processes, Geomorphology,
Water Quality, Groundwater
ESS30 98.4 Complete Complete Complete Yes Yes IFS, Ice Processes, Geomorphology,
Water Quality, Groundwater
ESS20 29.9 Complete Complete Complete Yes Yes IFS, Ice Processes, Geomorphology,
Water Quality, Groundwater
ESS15 24.7 Complete Complete Complete Yes Yes Ice Processes, Beluga
ESS10 17.4 Aug – Oct 2012;
Oct – Dec 2013
Aug – Oct 2012;
Oct – Dec 2013 Complete Yes Yes Ice Processes, Beluga
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Table 4.5-1. Common names, scientific names, life history strategies, and habitat use of fish species within the
Lower, Middle, and Upper Susitna River, based on sampling during the 1980s (from HDR 2011).
Common Name Scientific Name Life History Susitna Usage
Chinook salmon Oncorhynchus tshawytscha A M2, R
Chum salmon Oncorhynchus keta A M2, S
Coho salmon Oncorhynchus kisutch A M2, S, R
Pink salmon Oncorhynchus gorbuscha A M2
Sockeye salmon Oncorhynchus nerka A M2, S
Arctic grayling Thymallus arcticus F O, R, P
Alaska blackfish Dallia pectoralis F U
Arctic lamprey Lethenteron japonicum A,F O, M2, R, P
Bering cisco Coregonus laurettae A M2, S
Burbot Lota lota F O, R, P
Dolly Varden Salvelinus malma A,F O, P
Eulachon Thaleichthys pacificus A M2, S
Humpback whitefish Coregonus pidschian A,F O, R, P
Lake trout Salvelinus namaycush F U
Longnose sucker Catostomus catostomus F R, P
Northern pike Esox lucius F P
Pacific lamprey Lampetra tridentata A,F U
Rainbow trout Oncorhynchus mykiss F O, M2, P
Round whitefish Prosopium cylindraceum F O, M2, P
Sculpin Cottid spp. M1, F P
Threespine stickleback Gasterosteus aculeatus A,F M2, S, R, P
Notes:
A = anadromous
M1 = marine
F = freshwater
O=overwintering
R=rearing
P=present
M2 = migration
S=spawning
U=unknown
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Table 4.5-2. Priority ranking of fish species for development of site-specific Habitat Suitability Curves for the
Susitna River, Alaska.
Common Name Low Moderate High
Chinook salmon X
Chum salmon X
Coho salmon X
Pink salmon X
Sockeye salmon X
Arctic grayling
X
Arctic lamprey X
Bering cisco X
Burbot
X
Dolly Varden
X
Eulachon
X
Humpback whitefish
X
Lake trout X
Longnose sucker
X
Northern pike X
Rainbow trout
X
Round whitefish X
Sculpin X
Threespine stickleback X
Table 4.5-3. Summary of HSC curves developed during 1980s Susitna Studies.
Species Life Stage Depth Velocity Substrate Upwelling Cover Turbidity4
Coho Juvenile 1
Chinook Spawning
Juvenile 1
Sockeye Spawning
Juvenile 1
Chum Spawning 3
Juvenile 1
Pink Spawning 3
Rainbow Trout Spawning
Dolly Varden Adult 2
Arctic Grayling Adult 2
Humpback Whitefish Juvenile
Round Whitefish Adult 2
Longnose Sucker Adult 2
Burbot Adult
Notes:
1,2 Depth curves for multiple species combined
3 Integrated with substrate suitability
4 Separate curves developed for clear vs. turbid water for one or
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Table 4.5-4. Summary of habitat units selected from within each Focus Area for HSC sampling in 2013.
Macrohabitat Known Fish Use FA-104 FA-113 FA-115 FA-128 FA-138 FA-141 FA-144 Total
Main Channel No 2 1 1 2 2 1 2 11
Yes 1 1
Side Channel No 2 1 1 2 2 1 2 11
Yes 1 2 1 2 6
Side Slough No 2 2 4
Yes 2 2 2 6
Side Slough
Beaver Complex Yes 2 2
Upland Slough No 2 1 1 2 2 2 10
Yes 2 1 3
Upland Slough
Beaver Complex No 1 1 2
Tributary No 2 1 3
Yes 1 1 2
Tributary Mouth No 1 1
Yes 2 1 3
Plume Yes 1 1
Backwater No 1 1
Yes 1 1
Total 14 7 5 12 11 9 10 68
Notes:
FA-104 (Whiskers Slough), FA-113 (Oxbow 1), FA-115 (Slough 6A), FA-128 (Slough 8A), FA-138 (Gold Creek),
FA-141 (Indian River), FA-144 (Slough 21)
Table 4.5-5. Substrate classification system used 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 <1
2 Sand 0.05-0.1 1-2
3 Small Gravel 0.1-0.6 2-16
4 Large Gravel 0.6-2.5 16-64
5 Small Cobble 2.5-5.0 64-128
6 Large Cobble 5.0-10.0 128-256
7 Boulder >10.0 >256
8 Bedrock
Table 4.5-6. Summary of velocity meter and water quality probe specifications.
Parameter Instrument(s) Units Range Accuracy Precision
Temperature YSI ProPlus and
Hach HQ40d
˚C 0-70 ±0.3 0.1
Dissolved oxygen mg/L 0-20 ±0.2 0.01
Specific conductance µS/cm 0.1-400 ±0.5 0.01
Water velocity USGS Type AA (Price) m/s 0.05 – 20 ±1-6% --
Turbidity Hach 2100P NTU 0-1000 ±0.2% 0.01
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Table 4.6-1. 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 5.2-1. Metrics used to compare the representation and proportionality of habitat types between Focus
Areas and non-Focus Areas within each geomorphic reach.
Level1 Habitat Type Comparison Metric Numerator Denominator
Macro-Habitat
Main Channel Percent of main channel that
is single unsplit main channel
Length of main channel
habitat (HDR)
Total length of main
channel (thalweg, R2)
Split Main Channel Percent of main channel that
is in split main channel
Length of main channel
that is in split main
channel (R2 calculated)
Total length of main
channel (thalweg, R2)
Braided Main Channel Percent of main channel that
is in braided main channel
Length of main channel
that is in braided main
channel (R2 calculated)
Total length of main
channel (thalweg, R2)
Side Channel Side channel length per river
mile
Total length of side
channels (HDR)
Total length of main
channel (thalweg, R2)
Upland Slough Upland slough length per
river mile
Total length of upland
slough habitat (HDR)
Total length of main
channel (thalweg, R2)
Side Slough Side slough length per river
mile
Total length of side
channel habitat (HDR)
Total length of main
channel (thalweg, R2)
Backwater density of backwaters
(#/mile) # backwaters (HDR) Total length of main
channel (thalweg, R2)
Tributary density of tributaries (#/mile) # tributaries (HDR) Total length of main
channel (thalweg, R2)
Tributary Mouth density of tributary mouths
(#/mile)
# Tributary Mouths
(HDR)
Total length of main
channel (thalweg, R2)
Clear Water Plume density of plumes (#/mile) # plumes (HDR) Total length of main
channel (thalweg, R2)
Mesohabitat
Glide or Run Percent of main/side channel
habitat in glide/run
Total length of Glide or
Run (HDR)
Total Length of Main +
Side Channel Habitat
(HDR)
Riffle Percent of main/side channel
habitat in riffle
Total length of Riffle
(HDR)
Total Length of Main +
Side Channel Habitat
(HDR)
Beaver Complex Percent of slough habitat that
is beaver complex
Total length of Beaver
Complex Habitat (HDR)
Total length of slough
habitat (HDR)
Notes:
1 The habitat classifications in this table are those reflected in the RSP
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Table 5.2-2. Estimated bias for each proportionality metric (total for reach – Focus Area) where estimates
could be made. Statistical comparison was made using a t-test or nonparametric alternative when the sample
size (number of geomorphic reaches with bias estimate) was greater than three.
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8
Average
Bias p-value
Main Channel -5% -8.7% -18% 40% -33% -5% 0.70
Split Main 5% 8.7% 22.4% -40% 7% 0.6% 0.63
Braided Main -4.0% 26% 11% n/a
Side Channel -0.33 -0.10 0.021 0.13 -1.02 -0.26 0.28
Side Slough -0.46 0.155 -0.14 0.13 -0.42 -0.15 0.32
Upland Slough 0.04 -0.02 -0.43 -0.29 -0.1740 0.22
Backwaters 0.07 -0.018 -1.35 0.19 -0.28 1.00
Tributaries 0.18 -1.64 0.337 0.10 -0.66 -0.34 0.41
Tributary Mouth 0.36 -1.46 0.081 0.20 -0.20 0.88
Clear Water Plumes 0.33 -1.64 -0.018 0.07 -0.31 1.00
Beaver Complex -9.8% -25% -18% n/a
Glides/Runs -3.3% 4.43% 14.0% 4.0% 4.8% 0.27
Riffles 3.3% -4.43% -14.0% -4.0% -4.8% 0.27
Table 5.2-3. Identification of existing Focus Area boundaries and counterpart locations of areas selected via a
random systematic approach.
Geomorphic
Reach
Geomorphic Reach Focus Area1 Random Focus Area
Start End Length Start End Length Start End Length
MR-1 187.1 184.6 2.5 185.7 184.7 1 186.2 185.2 1
MR-2 184.6 169.6 15 175.4 173.6 1.8 181.4 179.8 1.6
173 171.6 1.4 175.0 173.4 1.6
MR-5 153.9 148.4 5.5 152.3 151.8 0.5 152.8 152.3 0.5
MR-6 148.4 122.7 25.7
145.7 144.4 1.3 146.8 145.3 1.5
143.4 141.8 1.6 140.8 139.3 1.5
140 138.7 1.3 134.8 133.3 1.5
129.7 128.1 1.6 128.8 127.3 1.5
MR-7 122.7 107.8 14.9 116.5 115.3 1.2 117.8 116.6 1.2
MR-8 107.8 102.4 5.4 106 104.8 1.2 104.9 103.7 1.2
Notes:
1 The Focus Areas used in this analysis were those presented in the RSP.
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Table 5.2-4. Estimated bias for each proportionality metric (total for reach – Focus Area) where estimates
could be made for random Focus Areas. Statistical comparison was made using a t-test or nonparametric
alternative when the sample size (number of geomorphic reaches with bias estimate) was greater than three.
MR-1 MR-2 MR-5 MR-6 MR-7 MR-8 Average Bias p-value
Main Channel 17% -9.5% -14% 17% 60% 14% 0.34
Split Main -17% 9.5% 7.5% -17% -31% -9.6% 0.29
Braided Main 6.3% -28% -11% n/a
Side Channel -0.31 -0.20 0.073 0.018 -0.15 -0.41 -0.16 0.084
Side Slough 0.17 -0.19 0.63 0.58 0.30 0.22
Upland Slough -0.17 0.17 0.13 -0.39 0.22 -0.0058 0.96
Backwaters 0.07 -0.011 0.20 0.19 0.11 0.12
Tributaries 1.2 0.20 -2.0 -1.1 0.57 -0.22 0.71
Tributary Mouth 0.045 0.40 -0.28 -1.4 -0.32 0.48
Clear Water Plumes 0.33 0.20 -0.011 -0.78 -0.07 0.81
Beaver Complex 7.9% -68% -30% n/a
Glides/Runs -3.3% -2.0% -0.54% -8.4% -1.9% -3.2% 0.078
Riffles 3.3% 2.0% 0.54% 8.4% 1.9% 3.2% 0.078
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Table 5.3-1. 2012 and provisional 2013 cross-sectional data ( indicate measured WSEs).
PRM
XS
Profile Date 1
XS
Profile Date 2
June/July 2012 August 2012 Sep/Oct 2012 June/July 20132 August 20132 Sep/Oct 20132
Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3
UPPER RIVER (PRM 261.3 - 187.1)
225.0 NA 6/14 26,932 NA 8/9 11,260 NA 10/18 1906.26 8/8 11,912 NA 9/3 14,696 NA
187.2 6/17/12 6/17 27,698 1466.42 8/6 14,707 1464.09 9/15 7,838 1461.81
MIDDLE RIVER (PRM 187.1 - 102.4)
186.2 6/18/12 6/18 24,493 1458.50 8/6 14,419 1457.07 9/15 7,630 1455.36
185.5 6/18/12 6/18 25,389 1452.14 8/6 1450.52 9/15 1449.17
185.2 6/19/12 6/19 26,676 1449.28 8/6 1447.37 9/15 1445.92
184.9 6/19/12 6/19 27,619 1446.04 8/6 14,239 1443.72 9/15 7,714 1442.10
184.4 6/19/12 6/19 27,886 1440.48 8/7 14,775 1437.43 9/15 8,353 1435.55
183.3 6/20/12 6/20 29,426 1424.86 8/7 14,183 1422.91 9/15 8,310 1421.75
182.9 6/20/12 6/20 29,128 1418.25 8/7 1416.49 9/15 1415.30
181.6 6/20/12 6/20 29,645 1402.27 8/7 14,705 1400.11 9/15 8,689 1398.98
179.5 6/21/12 6/21 30,866 1381.40 8/7 14,345 1377.74 9/14 8,361 1375.79
178.5 6/16/12 6/16 29,756 1370.75 8/7 14,799 1367.82 9/14 8,738 1366.14
176.5 6/21/12 6/21 31,240 1346.56 8/8 14,559 1344.03 9/16 10,768 1343.18
174.9 6/21/12 6/21 31,163 1329.91 8/8 1327.53 9/16 1326.88
173.1 6/21/12 6/21 30,571 1310.65 8/8 1307.89 9/16 11,082 1306.82
170.1 6/22/12 6/22 31,121 1285.05 8/8 14,568 1282.38 9/16 11,137 1281.59
168.1 6/22/12 6/22 32,265 1259.50 8/8 14,655 1256.43 9/17 14,619 1256.46
153.7 6/25/12 6/25 32,162 862.57 8/10 14,588 858.93
152.9 6/26/12 6/26 30,487 853.72 8/10 850.17
152.1 6/26/12 9/29/12 6/26 30,036 843.65 8/10 15,351 840.96 9/29 18,488 841.61
151.1 6/25/12 6/25 33,180 832.09 8/10 827.79 9/29 829.13
148.3 6/26/12 6/26 32,114 796.39 8/10 14,941 793.54 9/29 794.00
146.6 6/27/12 6/27 31,030 773.49 8/12 771.94 9/29 772.02
146.1 8/4/13 8/3 9/5
8/4
145.7 6/27/12 9/29/12 6/27 31,396 761.96 8/12 17,354 759.65 9/29 18,131 759.86 6/20 9/7
145.5 6/27/12 6/27 31,868 760.04 8/12 757.93 6/20 8/3 9/5
144.9 6/27/12 6/27 31,949 751.50 8/12 749.46 9/29 749.80 6/20
144.3 6/27/12 6/27 31,121 742.52 8/12 740.68 8/3 9/5
8/15
143.9 8/4/13 8/3 9/5
143.5 6/28/12 6/28 30,330 732.35 8/12 17,006 730.64 9/29 730.72 7/30
143.0 6/28/12 6/28 29,492 725.04 8/12 723.49 6/23 8/4 9/5
142.2 6/28/12 9/29/12 6/28 29,753 716.41 8/12 16,798 714.51 9/29 18,301 714.78 9/8
141.9 6/28/12 6/28 30,583 712.88 8/12 16,803 710.84 6/22 8/4 9/5
141.7 6/28/12 6/28 30,555 711.43 8/12 709.09 8/4 9/5
141.2 8/4/13 8/4 9/6
140.8 8/4/13 8/4 9/6
140.5 8/5/13 8/5 9/6
140.0 6/29/12 9/30/12 6/29 30,378 693.77 8/13 16,350 691.69 9/30 17,619 691.94 8/5 9/6
139.8 6/29/12 6/29 29,071 691.34 8/13 689.07 8/5 9/6
8/10
139.0 6/30/12 6/30 28,039 679.92 8/13 16,449 678.26 9/30 678.50 6/7 8/10 15,949 9/6
6/25
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PRM
XS Profile
Date 1
XS Profile
Date 2
June/July 2012 August 2012 Sep/Oct 2012 June/July 20132 August 20132 Sep/Oct 20132
Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3
7/28
138.7 6/30/12 6/30 28,230 678.08 8/13 16,344 677.07 8/5 9/6
8/10
138.4 8/5/13 8/5 9/6
138.1 6/30/12 6/30 28,203 670.43 8/13 669.00 9/30 669.36 8/5 9/6
8/10
137.6 6/30/12 9/30/12 6/30 27,893 664.17 8/13 16,409 662.67 9/30 17,382 662.58 8/10 15,702 9/6
137.2 8/5/13 8/5 9/6
136.7 7/1/12 7/1 26,756 654.82 8/13 653.46 8/5 9/6
136.2 7/1/12 7/1 26,943 648.86 8/13 648.12 8/6 9/6
135.6 8/6/13 8/6 9/6
135.0 7/1/12 7/1 26,526 634.86 8/13 15,627 632.97 8/6 9/6
134.7 8/6/13 8/6 9/6
134.3 7/2/12 10/1/12 7/2 25,463 627.51 8/13 625.41 10/1 15,568 625.68 8/6 9/6
134.1 7/2/12 7/2 26,166 625.74 8/14 16,491 624.10 8/7 9/12
133.8 7/2/12 7/2 25,715 623.51 8/14 16,275 622.22 8/7 9/12
133.3 7/2/12 7/2 25,678 618.46 8/14 617.34 8/7 9/12
132.6 7/2/12 7/2 25,046 609.97 8/14 16,039 608.67 8/7 9/12
132.0 8/7/13 8/7 9/12
131.4 7/3/12 7/3 28,628 598.37 8/14 597.82 8/7 9/10
130.9 8/8/13 8/8 9/10
130.4 8/9/13 8/9 9/10
129.7 7/3/12 10/1/12 7/3 28,243 580.58 8/14 16,330 578.98 10/1 15,731 579.02 6/27 9/10
128.1 7/4/12 7/4 26,748 564.50 8/15 15,926 563.54 8/9
127.8 8/9/13 8/9
126.8 7/4/12 10/1/12 7/4 27,608 552.41 8/15 16,078 550.87 10/1 15,582 551.04 7/9 23,082 8/11 16,185 9/12 31,059
126.4 8/10/13 8/10
126.1 7/5/12 7/5 27,248 546.88 8/15 545.26 8/11
125.8 8/11/13 8/11
125.4 7/5/12 7/5 26,427 541.32 8/15 540.09 8/10
124.9 8/11/13 8/11
124.5 8/11/13 8/11
124.1 7/5/12 10/1/12 7/5 26,132 530.43 8/15 16,161 529.24 10/1 15,582 529.40 7/9 22,514 8/11 16,603 9/10
9/12 30,632
123.7 7/6/12 7/6 23,875 527.93 8/15 527.43 8/11 9/10
123.2 8/12/13 8/12
122.7 7/6/12 7/6 23,331 518.91 8/15 517.91 8/12 9/9
122.6 7/6/12 7/6 22,890 517.85 8/15 16,287 516.97 8/12 9/9
122.1 8/12/13 8/12
121.4 8/12/13 8/12
120.7 7/6/12 7/6 22,687 502.03 8/15 501.13 8/12 9/9
120.3 8/12/13 8/12
119.9 7/7/12 10/3/12 7/7 20,715 495.29 8/16 16,005 494.37 10/3 13,998 493.97 7/9 22,745 8/14 9/9
118.9 8/14/13 8/14
118.4 7/7/12 7/7 20,656 485.32 8/16 484.18 10/3 484.62 8/14 9/9
117.9 8/14/13 8/14
117.4 7/7/12 7/7 20,747 477.82 8/16 477.21 8/14 9/9
117.0 8/14/13 8/14
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PRM
XS Profile
Date 1
XS Profile
Date 2
June/July 2012 August 2012 Sep/Oct 2012 June/July 20132 August 20132 Sep/Oct 20132
Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3
116.6 7/7/12 7/7 20,665 468.98 8/16 16,136 468.16 10/3 14,323 467.97 7/9 22,932 8/14 18,085 9/9
9/13 30,796
116.3 7/8/12 7/8 23,766 467.39 8/16 466.24 7/23 8/14
115.7 7/8/12 7/8 25,006 461.95 8/16 461.01 8/14
115.4 7/8/12 7/8 25,958 458.41 8/16 456.99 7/5 8/14
7/23
114.4 7/8/12 7/8 25,860 450.21 8/16 448.97 8/13
8/14
113.6 7/9/12 10/3/12 7/9 28,329 444.75 8/16 16,311 443.10 10/3 13,476 442.90 8/14
8/14 18,135
113.1 8/15/13 8/14
8/15
112.5 8/15/13 8/15
111.9 7/9/12 7/9 28,296 429.73 8/17 427.98 8/15
110.5 7/9/12 10/3/12 7/9 28,825 417.55 8/17 15,254 415.70 10/3 14,172 415.49 8/15
109.0 8/15/13 8/15
108.3 8/18/12 8/17 16,394 396.50 8/15 9/7
107.8 8/15/13 8/15
107.1 7/9/12 7/9 28,409 387.63 8/18 15,508 385.44 10/4 14,558 385.12 7/11 19,719 8/15 18,921 9/7
9/15 21,713
106.6 8/15/13 8/15
106.1 8/18/12 8/18 15,278 377.95 10/4 377.75 8/15 9/7
105.3 8/18/12 8/18 15,362 372.01 8/16 9/7
104.7 8/18/12 8/18 15,377 367.05 10/4 366.93 8/16
104.1 8/19/12 8/19 15,345 364.79 8/16 9/6
103.5 10/1/12 10/4 14,575 358.05 8/16 9/6
102.7 7/10/12 7/10 26,635 352.87 8/19 351.70 8/16
LOWER RIVER (PRM 102.4 - 3.3)
102.1 8/16/13 8/16
101.4 7/10/12 10/15/1
2 7/10 346.09 8/19 344.82 10/15 343.67
100.7
6/10/13 -
6/11/13,
6/10 8/1
7/17/13 7/17
99.9 6/11/13 6/10 8/1
6/11
98.4 7/11/12 10/5/12 7/11 46,499 326.86 8/20 40,623 326.37 10/5 39,065 326.08 8/1
97.0 7/11/12 7/11 45,118 318.49 8/20 40,261 318.38 10/5 318.21 8/1
96.2 6/12/13 6/12 8/1
94.8 6/12/13 6/12 8/1 53,839
7/18 8/2
94.0 6/13/13 6/13
7/18
93.2 6/13/13 6/13 8/2
92.3 6/13/13 6/13 8/2
7/18
91.6 8/21/12 8/21 46,330 285.74 8/2
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PRM
XS Profile
Date 1
XS Profile
Date 2
June/July 2012 August 2012 Sep/Oct 2012 June/July 20132 August 20132 Sep/Oct 20132
Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3
91.0 7/12/12 7/12 43,922 282.34 8/21 46,197 282.34 8/2
90.2 6/14/13 6/14 8/3 51,896
89.5 6/14/13 6/14 8/2
7/18
88.4 8/22/12 8/22 41,697 268.25 8/3
88.0 6/15/13 6/15 8/3
87.6 6/15/13 6/15 8/3 52,697
87.1 7/12/12 7/12 42,550 263.24 8/22 262.89 8/3
86.3 7/13/12 7/13 41,895 258.59 8/22 258.39 8/3
85.4 8/22/12 8/22 40,468 255.18 8/3
84.4 8/23/12 8/23 36,933 251.19 8/3
83.0 7/13/12 7/13 41,975 245.29 8/23 244.93 8/4
82.3 8/23/12 8/23 37,947 241.19 8/4
81.4 6/16/13 6/16 8/4
80.7 6/16/13 6/16 8/4
80.0 8/24/12 8/24 36,503 229.51 8/4
79.0 6/17/13 6/17 8/4
78.0 6/17/13 6/17 8/4 52,133 9/20
77.0 6/18/13 6/18
75.9 6/18/13 6/18 8/5 9/20
8/20
75.0 6/19/13 6/19
74.1 6/19/13 6/19 8/5
73.1 6/20/13 6/20 8/5 51,077 9/20
71.0 6/20/13 6/20 8/5 9/20
6/21 8/26
69.2 6/23/13 6/23 8/5 9/20
68.2 6/23/13 6/25 8/5
67.2 6/23/13 6/25 8/6 45,437 9/20
66.1 6/24/13 6/25 8/6
64.6 6/26/13 6/27 8/6 9/20
62.7 6/27/13 6/27 8/6 9/20
60.3 6/26/13 6/27 8/6 9/18
59.1 6/28/13 6/28
57.8 6/28/13 6/28 8/6 9/18
8/27
55.4 6/29/13 6/29 8/27 9/18
54.2 6/30/13 6/30 8/27 9/16 50,633
9/18
52.1 7/2/13 7/2 8/28
7/3
49.0 7/4/13 7/4 8/28 9/12
9/18 44,070
47.9 7/4/13 7/4 8/28
47.1 7/5/13 7/5 8/28
46.3 7/5/13 7/7 8/28 9/12
9/18
45.6 7/7/13 7/7 8/29
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PRM
XS Profile
Date 1
XS Profile
Date 2
June/July 2012 August 2012 Sep/Oct 2012 June/July 20132 August 20132 Sep/Oct 20132
Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs1 WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3 Date Q, cfs WSE3
44.5 7/7/13 7/7 8/29 9/12
9/18
41.3 7/8/13 7/8 8/29
40.4 7/8/13 -
7/10/13 7/8 8/29 9/19 44,519
39.5 7/10/13
-
7/11/13
7/10 8/29 9/12
9/19
38.3 7/11/13 -
7/12/13
7/12 8/29
7/18
36.4 7/11/13 7/13 9/15
9/20 40,858
34.8 7/13/13
7/14 9/12
9/15
9/19
9/21 38,056
33.7 7/14/13 7/14 8/30
32.4 7/14/13 7/15 8/30
31.6 7/15/13 7/13
29.9 7/15/13 9/11 40.16 7/15 8/30 9/9
9/19
Notes:
Bold PRMs indicates a new cross-section collected in 2013.
1 Data approved by HDR, 5/1/13: "Quality Assurance / Quality Control Review of ADCP Discharge Data collected by Brailey Hydrologic - Draft."
2 Data collected in 2013 are provisional pending final review and approval.
3 WSE = water surface elevation (feet, NAVD 88). WSE was measured during, or within 2 hours of, the flow measurement, typically at left and right banks of all
channels.
The average WSE of the main channel is reported here.
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Table 5.3-2. Summary of Focus Area measurements.
FA-144 (Slough 21)
Date Time Transect Proportion of Total Flow Flow (cfs), adjusted to match Focus Area Total Focus 95%
Area Total Uncertainty,
Far left Left Middle Right Far right Far left Left Middle Right Far right Flow, cfs percent
6/29/2013 16:02 T1 0.0809 R 2,104 R 26,020 10.4
9/7/2013 14:46 T1 0.0849 0.915 2,234 24,091 26,325 3.5
6/29/2013 14:43 T2 0.0183 0.982 475 25,545 26,020 7.1
9/7/2013 14:32 T2 0.0178 0.982 469 25,897 26,366 7.1
6/29/2013 14:26 T3 0.0105 0.273 0.716 274 7,114 18,632 26,020 10.4
9/7/2013 14:05 T3 0.0092 0.258 0.733 244 6,825 19,374 26,442 7.1
6/29/2013 13:26 T4 0.0023 0.998 59 25,961 26,020 10.4
9/7/2013 13:25 T4 0.0009 0.999 23 26,529 26,552 7.1
6/29/2013 13:05 T5 single channel 26,020 26,020 2.7
9/7/2013 13:14 T5 single channel 26,583 26,583 1.9
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Table 5.3-2. Summary of Focus Area measurements (continued).
FA-141 (Indian River)
Date Time Transect Proportion of Total Flow Flow (cfs), adjusted to match Focus Area Total Focus 95%
Area Total Uncertainty,
Far left Left Middle Right Far right Far left Left Middle Right Far right Flow, cfs percent
6/30/2013 13:53 T1 single channel 24,992 24,992 1.96
9/8/2013 15:10 T1 single channel 30,551 30,551 1.53
6/30/2013 13:18 T2 single channel 24,835 24,835 1.96
9/8/2013 15:04 T2 single channel 30,546 30,546 1.53
6/30/2013 13:05 T3 0.4870 0.513 12,112 12,757 24,869 7.1
9/8/2013 14:04 T3 0.4964 0.504 14,650 14,865 29,515 3.8
6/30/2013 11:51 T4 0.8335 0.167 20,893 4,175 25,068 23.6
9/8/2013 12:42 T4 0.8339 0.166 24,554 4,890 29,444 3.5
6/30/2013 11:29 T5 single channel 25,130 25,130 1.96
9/8/2013 12:30 T5 single channel 29,434 29,434 1.53
6/30/2013 14:27 T6 0.0583 1,437 24,650 3.8
9/8/2013 13:04 T6 0.0591 1,800 30,443 3.5
6/30/2013 14:36 T7 0.0992 2,443 24,625 3.8
9/8/2013 13:29 T7 0.0939 2,862 30,465 3.5
6/30/2013 15:30 T8 0.000051 1.24 24,481 >50
6/30/2013 15:45 T9 -0.000032 -0.78 24,441 >50
6/30/2013 15:59 T10 -0.000026 -0.63 24,402 >50
9/8/2013 14:35 T11 0.000123 3.76 30,521 >50
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Table 5.3-2. Summary of Focus Area measurements (continued).
FA-138 (Gold Creek)
Date Time Transect Proportion of Total Flow Flow (cfs), adjusted to match Focus Area Total Focus 95%
Area Total Uncertainty,
Far left Left Middle Right Far right Far left Left Middle Right Far right Flow, cfs percent
7/1/2013 14:37 T1 see T6/T7 0.141 R see T6/T7 3,520 25,001 3.8
9/9/2013 13:32 T1 0.1522 0.145 0.703 4,383 4,181 20,228 28,793 7.1
7/1/2013 13:51 T2 single channel 25,001 25,001 3.2
9/9/2013 13:10 T2 single channel 28,841 28,841 1.14
7/1/2013 12:44 T3 0.817 0.025 20,434 621 25,001 7.1
9/9/2013 11:59 T3 0.1544 0.815 0.031 4,478 23,629 887 28,994 7.1
7/1/2013 12:28 T4 0.0066 0.993 165 24,837 25,001 23.6
9/9/2013 11:48 T4 0.008 0.992 247 28,771 29,017 3.8
7/1/2013 11:57 T5 single channel 25,001 25,001 3.18
9/9/2013 11:24 T5 single channel 29,068 29,068 1.14
7/1/2013 14:52 T6 0.130 3,258 25,001 7.1
9/9/2013 14:08 T6 0.141 4,050 28,714 7.1
7/1/2013 15:03 T7 0.007 183 25,001 26.9
9/9/2013 14:19 T7 0.012 346 28,692 3.8
7/1/2013 15:18 T8 0.00038 10 25,001 >50
9/9/2013 14:01 T8 0.00021 6 28,729 >50
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Table 5.3-2. Summary of Focus Area measurements (continued).
FA-128 (Slough 8A)
Date Time Transect Proportion of Total Flow Flow (cfs), adjusted to match Focus Area Total Focus 95%
Area Total Uncertainty,
Far left Left Middle Right Far right Far left Left Middle Right Far right Flow, cfs percent
7/2/2013 13:14 T1 0.304 0.696 7,520 17,197 24,717 7.1
9/10/2013 14:03 T1 0.327 0.673 8,547 17,551 26,098 3.5
7/2/2013 12:46 T2 0.010 0.251 0.0311 0.718 236 6,204 766 17,710 24,916 7.1
9/10/2013 13:40 T2 0.267 0.0434 0.690 6,960 1,134 18,019 26,113 7.1
7/2/2013 12:12 T3 0.0154 0.237 0.747 379 5,843 18,413 24,635 3.5
9/10/2013 13:13 T3 0.0181 0.242 0.740 473 6,331 19,328 26,132 7.1
7/2/2013 11:26 T4 3.7E-04 0.0152 0.107 0.522 0.356 9.10 374 2,629 12,818 8,745 24,575 3.8
9/10/2013 12:20 T4 0.0181 0.111 0.522 0.349 473 2,907 13,659 9,127 26,167 7.1
7/2/2013 10:58 T5 single channel 24,538 24,538 3.2
9/10/2013 11:54 T5 single channel 26,184 26,184 1.1
7/2/2013 12:24 T6 0.0094 231 24,651 4.0
9/10/2013 13:26 T6 0.0096 250 26,123 13.7
7/2/2013 15:36 T7 1.2E-04 2.95 24,905 >20
9/10/2013 15:10 T7 1.4E-04 3.68 26,053 7.1
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Table 5.3-2. Summary of Focus Area measurements (continued).
FA-115 (Slough 6A)
Date Time Transect Proportion of Total Flow Flow (cfs), adjusted to match Focus Area Total Focus 95%
Area Total Uncertainty,
Far left Left Middle Right Far right Far left Left Middle Right Far right Flow, cfs percent
7/10/2013 14:09 T1 0.100 0.900 2,165 19,484 21,649 10.4
9/13/2013 13:21 T1 0.100 0.900 3,077 27,715 30,792 3.8
7/10/2013 12:53 T2 0.751 0.249 16,275 5,409 21,683 3.8
9/13/2013 12:53 T2 0.707 0.293 21,756 9,036 30,792 3.5
7/10/2013 11:23 T3 0.000 0.253 0.000 5 5,493 1 21,725 3.8
9/13/2013 14:07 T3 0.013 0.986 0.001 415 30,354 23 30,792 3.5
7/10/2013 12:43 T4 0.745 0.255 16,154 5,534 21,688 3.8
9/13/2013 12:43 T4 0.707 0.293 21,783 9,009 30,792 3.5
7/10/2013 12:08 T5 single channel 21,705 21,705 1.31
9/13/2013 12:26 T5 single channel 30,792 30,792 0.85
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Table 5.3-2. Summary of Focus Area measurements (continued).
FA-113 (Oxbow 1)
Date Time Transect Proportion of Total Flow Flow (cfs), adjusted to match Focus Area Total Focus 95%
Area Total Uncertainty,
Far left Left Middle Right Far right Far left Left Middle Right Far right Flow, cfs percent
7/11/2013 15:26 T1 single channel 19,715 19,715 1.4
9/14/2013 15:41 T1 single channel 25,101 25,101 1.06
7/11/2013 15:05 T2 0.999 0.001 19,701 24 19,725 13.7
9/14/2013 15:08 T2 0.994 0.006 25,101 150 25,251 7.1
7/11/2013 14:49 T3 0.999 0.001 19,710 24 19,733 7.1
9/14/2013 14:56 T3 0.994 0.006 25,154 152 25,306 3.5
7/11/2013 13:26 T4 0.189 0.001 3747 24 19,775 3.5
9/14/2013 14:27 T4 0.218 0.782 5,537 19,899 25,436 3.5
7/11/2013 11:56 T5 0.166 0.834 3,288 16,532 19,820 3.8
9/14/2013 11:49 T5 0.196 0.804 5,127 21,026 26,153 3.8
7/11/2013 13:48 T6 0.075 0.925 1490 18,350 19,840 3.8
9/14/2013 11:40 T6 0.069 0.931 1815 24,380 26,195 3.8
7/10/2013 14:09 T7 0.071 0.929 1526 20,122 21,649 7.10
9/14/2013 11:22 T7 0.068 0.932 1800 24,474 26,274 3.8
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Table 5.3-2. Summary of Focus Area measurements (continued).
FA-104 (Whiskers Slough)
Date Time Transect
Proportion of Total Flow Flow (cfs), adjusted to match Focus Area Total
Focus 95%
Area Total
Flow, cfs
Uncertainty,
percent Far left Left Middle Right Far right Far left Left Middle Right Far right
7/12/2013 13:44 T1 0.00008 0.006 0.843 0.150 1.48 113 14,756 2,629 17,498 7.1
9/15/2013 15:01 T1 0.00013 0.018 0.811 0.172 2.74 377 17,345 3,675 21,396 3.8
7/12/2013 11:55 T2 0.837 0.163 14,640 2,858 17,498 10.4
9/15/2013 13:11 T2 0.818 0.182 17,606 3,914 21,520 3.8
7/12/2013 11:44 T3 0.992 0.008 17353 145 17,498 3.8
9/15/2013 13:01 T3 0.976 0.024 21,020 511 21,531 3.8
7/12/2013 11:34 T4 single channel 17,498 17,498 2.3
9/15/2013 12:51 T4 single channel 21,546 21,546 1.06
7/12/2013 13:34 T5 0.005 0.001 91 14 17,498 3.8
9/15/2013 14:46 T5 0.011 0.003 236 63 21,413 3.8
7/12/2013 12:20 T6 0.147 2,576 17,498 3.50
9/15/2013 13:26 T6 0.161 3,471 21,503 3.5
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Table 5.3-3. Tributary gaging streamflow and staff gage measurements collected in 2013.
Location Field Visit 1 (Jun/Jul) Field Visit 2 (Aug) Unscheduled Field Visit Field Visit 3 (Sep/Oct)
Date Q (cfs) SG (ft) Date Q (cfs) SG (ft) Date Q (cfs) SG (ft) Date Q (cfs) SG (ft)
Oshetna River1 7/13/2013 1.55 8/9/2013 604.7 1.42 9/3/2013 1000 2.2 9/26/2013 1.44
Kosina Creek 7/13/2013 620 1.46 8/7/2013 610 1.38 9/26/2013 1.53
Unnamed Tributary
144.6
7/12/2013 0.33 NA 8/7/2013 0 NA 9/15/2013 17.9 NA 9/26/2013 12.2 NA
Indian River 7/11/2013 231.5 1.61 8/9/2013 136.8 1.28 9/28/2013 286.3 1.68
Skull Creek 7/12/2013 7.4 0.96 8/8/2013 2.5 0.75 9/13/2013 48.5 1.6 9/29/2013 13.7 1.15
Gash Creek 6/16/2013 2.4 1.12 8/8/2013 2.9 1.00 9/29/2103 5.3 1.13
Slash Creek 6/16/2013 0.17 NA 8/8/2013 0.031 NA 9/29/2013 0.28 NA
Unnamed Tributary
113.7
6/16/2013 2.3 1.26 8/8/2013 0.3 1.00 9/29/2013 4.9 1.42
Whiskers Creek 6/22/2013 17.6 1.99 8/6/2013 5.7 1.75 9/11/2013 147.7 3.59 9/30/2013 39.3 2.41
Trapper Creek 6/17/2103 31.7 1.26 8/6/2013 10.8 1.01 9/30/2013 89.7 1.7
Birch Creek 7/14/2013 35.1 1.85 8/9/2013 23.9 1.76 9/27/2013 82.3 2.33
Deshka River2 7/15/2013 317.4 95.45 8/10/2013 245 95.3 9/27/2013 98.41
Note:
1 Note that discharge measurements collected for the Oshetna River were measured on different dates than when surveying and data downloading occurred.
2 Note that no staff gage was installed at the Deshka River site so the staff gage reading is the measured water surface elevation.
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Table 5.4-1. USGS Gage No. 15292000 – Susitna River at Gold Creek (cfs).
Water
Year Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
1950 6,335 2,583 1,439 1,027 788 726 870 11,511 19,600 22,600 19,877 8,301 8,032
1951 3,848 1,300 1,100 960 820 740 1,617 14,089 20,787 22,568 19,674 21,243 9,106
1952 5,571 2,744 1,900 1,600 1,000 880 920 5,419 32,370 26,387 20,923 14,480 9,552
1953 8,202 3,497 1,700 1,100 820 820 1,615 19,271 27,323 20,197 20,610 15,273 10,091
1954 5,604 2,100 1,500 1,300 1,000 780 1,235 17,281 25,250 20,358 26,097 12,916 9,681
1955 5,370 2,760 2,045 1,794 1,400 1,100 1,200 9,319 29,860 27,558 25,752 14,288 10,256
1956 4,951 1,900 1,300 980 970 940 950 17,665 33,343 31,090 24,532 18,333 11,474
1957 5,806 3,050 2,142 1,700 1,500 1,200 1,200 13,755 30,163 23,306 20,539 19,800 10,384
1958 8,212 3,954 3,264 1,965 1,307 1,148 1,533 12,896 25,700 22,877 22,542 7,550 9,476
1959 4,811 2,150 1,513 1,448 1,307 980 1,250 15,987 23,323 25,000 31,181 16,924 10,560
1960 6,558 2,850 2,200 1,845 1,452 1,197 1,300 15,781 15,533 22,977 23,594 20,510 9,713
1961 7,794 3,000 2,694 2,452 1,754 1,810 2,650 17,361 29,453 24,574 22,103 13,373 10,810
1962 5,916 2,700 2,100 1,900 1,500 1,400 1,700 12,590 43,273 25,855 23,555 15,890 11,566
1963 6,723 2,800 2,000 1,600 1,500 1,000 830 19,026 26,000 34,400 23,674 12,318 11,073
1964 6,449 2,250 1,494 1,048 966 713 745 4,307 50,577 22,945 16,435 9,571 9,799
1965 6,291 2,799 1,211 960 860 900 1,360 12,987 25,720 27,842 21,116 19,351 10,168
1966 7,205 2,098 1,631 1,400 1,300 1,300 1,775 9,645 32,953 19,865 21,826 11,753 9,432
1967 4,163 1,600 1,500 1,500 1,400 1,200 1,167 15,481 29,513 26,800 32,623 16,867 11,219
1968 4,900 2,353 2,055 1,981 1,900 1,900 1,910 16,177 31,550 26,423 17,168 8,816 9,810
1969 3,822 1,630 882 724 723 816 1,510 11,045 15,503 16,103 8,879 5,093 5,597
1970 3,124 1,215 866 824 768 776 1,080 11,381 18,633 22,661 19,977 9,121 7,591
1971 5,288 3,407 2,290 1,442 1,036 950 1,082 3,745 32,933 23,948 31,906 14,442 10,251
1972 5,847 3,093 2,510 2,239 2,028 1,823 1,710 21,887 34,430 22,768 19,287 12,403 10,885
1973 4,826 2,253 1,465 1,200 1,200 1,000 1,027 8,235 27,803 18,252 20,290 9,074 8,087
1974 3,733 1,523 1,034 874 777 724 992 16,181 17,867 18,797 16,218 12,246 7,630
1975 3,739 1,700 1,603 1,516 1,471 1,400 1,593 15,355 32,310 27,716 18,094 16,307 10,276
1976 7,739 1,993 1,081 974 950 900 1,373 12,623 24,380 18,935 19,796 6,881 8,189
1977 3,874 2,650 2,403 1,829 1,618 1,500 1,680 12,677 37,967 22,868 19,235 12,636 10,108
1978 7,571 3,525 2,589 2,029 1,668 1,605 1,702 11,945 19,050 21,019 16,394 8,607 8,194
1979 4,907 2,535 1,681 1,397 1,286 1,200 1,450 13,868 24,690 28,881 20,461 10,774 9,490
1980 7,311 4,192 2,416 1,748 1,466 1,400 1,670 12,065 29,080 32,658 20,965 13,281 10,748
1981 7,725 3,569 1,915 2,013 1,975 1,585 2,040 16,550 19,300 33,935 37,871 13,786 11,960
1982 7,463 3,260 1,877 1,681 1,486 1,347 1,783 13,384 26,100 24,123 15,274 17,783 9,669
1983 6,892 2,633 2,358 2,265 1,996 1,690 1,900 14,945 24,510 21,145 24,500 13,585 9,924
1984 8,301 3,153 2,258 2,048 1,969 1,900 1,810 12,961 26,773 23,542 20,397 9,429 9,599
1985 5,670 3,093 2,394 1,939 1,643 1,726 1,977 11,171 26,333 26,510 19,919 15,637 9,881
1986 6,944 2,673 1,929 1,658 1,561 1,394 1,565 12,084 20,007 21,868 17,252 12,860 8,531
1987 12,675 3,450 1,955 1,615 1,518 1,500 2,048 12,990 22,997 29,890 21,752 13,339 10,551
1988 5,924 2,483 1,600 1,561 1,500 1,500 1,587 17,371 29,723 25,690 19,542 13,781 10,241
1989 7,674 3,013 2,000 2,000 1,800 1,800 2,137 13,742 26,770 23,652 22,390 15,433 10,252
1990 8,025 2,997 1,848 1,765 1,700 1,852 4,250 25,632 33,803 23,513 23,732 26,507 13,018
1991 6,895 2,447 2,200 1,897 1,800 1,619 1,613 6,048 25,627 21,219 18,281 12,347 8,532
1992 5,817 2,440 2,200 1,965 1,800 1,868 2,100 6,104 23,140 25,535 21,145 10,175 8,739
1993 4,379 2,733 2,039 1,865 1,754 1,639 2,537 20,881 23,483 19,345 18,745 21,287 10,099
1994 9,915 3,327 2,529 2,058 1,786 1,526 3,221 14,612 31,087 20,961 18,581 9,357 9,960
1995 4,530 2,780 2,097 1,855 1,718 1,700 2,846 17,712 24,710 25,497 18,381 19,137 10,294
1996 6,482 2,657 1,442 1,248 1,186 1,100 1,350 6,613 15,707 16,006 17,132 10,412 6,816
1997 3,505 1,955 1,748 1,626 1,515 1,405 1,642 9,660 19,100 24,435 24,748 13,592 8,800
1998 3,939 1,781 1,551 1,412 1,353 1,290 1,748 9,616 24,597 25,790 22,797 16,151 9,382
1999 7,739 3,040 2,110 1,698 1,417 1,224 1,412 9,380 23,073 22,923 25,448 11,354 9,294
2000 6,892 3,101 2,019 1,674 1,539 1,440 1,721 11,515 31,280 29,468 16,381 15,505 10,253
2001 8,110 3,067 2,101 1,770 1,593 1,482 1,619 9,016 31,000 22,048 21,790 10,355 9,539
2002 4,840 2,627 1,897 1,548 1,421 1,303 1,330 11,506 16,547 18,148 23,781 16,250 8,483
2003 10,953 5,394 2,590 1,655 2,243 1,509 2,173 8,019 24,330 29,200 21,119 13,513 10,278
2004 8,109 2,500 1,810 1,471 1,276 1,081 2,730 23,574 25,330 20,158 17,723 6,452 9,419
2005 3,300 1,733 1,610 1,439 1,239 1,045 2,611 26,942 34,323 26,761 21,974 22,857 12,207
2006 8,238 2,143 1,497 1,400 1,389 1,361 1,535 15,734 23,287 23,142 30,813 12,303 10,314
2007 10,388 3,140 2,319 2,024 1,905 1,744 2,273 17,190 19,707 21,584 19,265 13,504 9,649
2008 5,017 3,222 2,813 1,842 1,343 1,360 1,670 11,865 21,120 22,032 19,726 14,520 8,926
2009 5,529 1,548 1,300 1,385 1,300 1,340 4,547 22,932 23,113 19,368 18,474 12,481 9,499
2010 7,122 2,807 1,842 1,468 1,350 1,305 1,847 19,606 20,023 27,519 20,077 15,824 10,137
Average 6,319 2,672 1,893 1,593 1,420 1,303 1,743 13,785 26,292 23,988 21,382 13,737 9,729
Maximum 12,675 5,394 3,264 2,452 2,243 1,900 4,547 26,942 50,577 34,400 37,871 26,507 13,018
Minimum 3,124 1,215 866 724 723 713 745 3,745 15,503 16,006 8,879 5,093 5,597
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Table 5.4-2. Inflows to Watana Reservoir (cfs).
Water
Year Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
1950 5,164 2,078 1,149 817 625 575 691 9,449 16,180 18,678 16,401 6,777 6,599
1951 3,113 1,037 876 763 651 587 1,295 11,586 17,169 18,646 16,234 17,550 7,495
1952 4,529 2,210 1,522 1,280 795 699 731 4,435 26,820 21,830 17,270 11,907 7,865
1953 6,697 2,825 1,360 876 651 651 1,295 15,900 22,627 16,668 17,014 12,566 8,306
1954 4,554 1,684 1,199 1,037 795 618 986 14,253 20,892 16,795 21,560 10,602 7,966
1955 4,359 2,222 1,641 1,436 1,118 876 956 7,637 24,756 22,821 21,212 11,746 8,442
1956 4,017 1,522 1,037 779 771 747 755 14,578 27,534 25,800 20,308 15,123 9,465
1957 4,720 2,458 1,719 1,360 1,199 956 956 11,328 24,990 19,270 16,950 16,339 8,551
1958 6,702 3,198 2,634 1,575 1,043 915 1,226 10,601 21,269 18,907 18,589 6,155 7,787
1959 3,900 1,725 1,209 1,157 1,043 779 997 13,194 19,282 20,688 25,674 13,943 8,691
1960 5,342 2,295 1,768 1,477 1,160 954 1,038 12,995 12,773 18,997 19,511 16,930 7,989
1961 6,362 2,418 2,169 1,971 1,404 1,449 2,133 13,638 22,784 19,841 19,479 10,148 8,701
1962 4,638 2,263 1,760 1,609 1,257 1,177 1,457 11,333 36,020 23,446 19,890 12,746 9,834
1963 5,560 2,509 1,709 1,309 1,185 884 777 15,297 20,663 28,767 21,012 10,799 9,277
1964 5,187 1,789 1,195 852 782 575 609 3,579 42,839 20,081 14,044 7,524 8,262
1965 4,759 2,368 1,070 863 773 807 1,232 10,964 21,214 23,236 17,392 16,226 8,451
1966 5,221 1,565 1,204 1,060 985 985 1,338 7,094 25,941 16,154 17,387 9,216 7,374
1967 3,270 1,202 1,122 1,102 1,031 890 850 12,556 24,715 21,989 26,106 13,670 9,096
1968 4,019 1,934 1,704 1,618 1,560 1,560 1,577 12,825 25,704 22,086 14,144 7,164 8,032
1969 3,135 1,355 754 619 608 686 1,262 9,311 13,962 14,844 7,772 4,260 4,912
1970 2,403 1,021 709 636 602 624 986 9,537 14,401 18,411 16,264 7,224 6,115
1971 3,768 2,496 1,687 1,097 777 717 814 2,857 27,613 21,125 27,445 12,190 8,588
1972 4,979 2,587 1,957 1,671 1,491 1,366 1,305 15,972 27,428 19,818 17,509 10,957 8,963
1973 3,913 1,810 1,171 956 956 795 817 6,741 22,974 15,046 16,755 7,418 6,641
1974 3,019 1,217 822 694 616 574 789 13,361 14,726 15,498 13,353 10,050 6,268
1975 3,025 1,360 1,282 1,212 1,176 1,118 1,274 12,661 26,784 22,963 14,915 13,424 8,468
1976 6,314 1,599 860 775 755 715 1,098 10,361 20,170 15,619 16,343 5,603 6,728
1977 3,132 2,133 1,932 1,464 1,294 1,199 1,344 10,439 31,366 18,902 15,870 10,367 8,311
1978 6,174 2,847 2,083 1,627 1,335 1,284 1,362 9,803 15,712 17,360 13,502 7,030 6,720
1979 3,980 2,039 1,345 1,116 1,025 956 1,158 11,429 20,429 23,937 16,892 8,823 7,812
1980 5,959 3,393 1,942 1,399 1,171 1,118 1,337 9,846 23,400 26,741 18,006 10,995 8,827
1981 6,632 3,044 1,790 1,858 1,592 1,262 1,641 14,415 16,737 27,598 30,542 11,666 9,984
1982 5,700 2,468 1,596 1,380 1,104 971 1,196 10,878 21,441 20,442 13,203 13,979 7,898
1983 5,154 2,132 1,893 1,797 1,610 1,427 1,565 11,671 20,603 18,768 20,863 11,194 8,270
1984 6,882 2,657 1,939 1,782 1,741 1,697 1,613 10,831 22,911 20,708 17,420 7,347 8,174
1985 4,257 2,384 1,799 1,479 1,273 1,298 1,517 8,440 21,226 23,295 16,433 11,700 7,966
1986 5,073 2,039 1,425 1,207 1,131 1,038 1,162 9,736 17,817 20,425 14,207 10,558 7,193
1987 10,415 2,786 1,567 1,292 1,213 1,199 1,644 10,671 19,016 24,765 17,964 10,962 8,686
1988 4,814 1,997 1,280 1,248 1,199 1,199 1,269 14,335 24,637 21,261 16,119 11,326 8,434
1989 6,262 2,429 1,602 1,602 1,441 1,441 1,715 11,292 22,163 19,554 18,497 12,695 8,433
1990 6,552 2,416 1,480 1,413 1,360 1,483 3,446 21,223 28,001 19,439 19,627 21,863 10,733
1991 5,622 1,968 1,768 1,519 1,441 1,295 1,290 4,934 21,210 17,526 15,071 10,130 7,008
1992 4,730 1,962 1,768 1,574 1,441 1,496 1,685 4,985 19,122 21,130 17,459 8,331 7,180
1993 3,546 2,200 1,634 1,493 1,404 1,311 2,042 17,252 19,421 15,957 15,458 17,589 8,310
1994 8,116 2,685 2,034 1,650 1,429 1,220 2,603 12,014 25,724 17,312 15,321 7,654 8,185
1995 3,670 2,239 1,682 1,485 1,375 1,360 2,293 14,604 20,451 21,099 15,152 15,779 8,471
1996 5,278 2,139 1,152 995 945 876 1,078 5,403 12,922 13,169 14,113 8,524 5,581
1997 2,815 1,561 1,389 1,277 1,176 1,078 1,282 7,885 15,738 20,166 20,415 11,132 7,206
1998 3,171 1,418 1,210 1,084 1,031 977 1,370 7,856 20,300 21,280 18,812 13,257 7,686
1999 6,285 2,434 1,684 1,344 1,089 917 1,087 7,662 19,026 18,902 20,946 9,273 7,603
2000 5,588 2,483 1,612 1,321 1,199 1,110 1,354 9,415 25,738 24,263 13,455 12,724 8,390
2001 6,592 2,456 1,676 1,411 1,249 1,147 1,271 7,376 25,715 18,217 18,001 8,479 7,835
2002 3,925 2,114 1,520 1,238 1,135 1,040 1,061 9,473 13,624 14,959 19,678 13,376 6,969
2003 8,973 4,380 2,084 1,324 1,802 1,207 1,750 6,553 20,125 24,139 17,450 11,110 8,452
2004 6,627 2,010 1,449 1,176 1,018 860 2,203 19,489 20,957 16,635 14,600 5,252 7,745
2005 2,663 1,387 1,288 1,149 988 832 2,112 22,327 28,455 22,160 18,157 18,893 10,079
2006 6,732 1,720 1,196 1,118 1,109 1,086 1,227 12,996 19,261 19,131 25,426 10,093 8,489
2007 8,517 2,532 1,864 1,622 1,526 1,396 1,827 14,166 16,260 17,828 15,887 11,095 7,928
2008 4,071 2,599 2,265 1,476 1,072 1,086 1,336 9,736 17,438 18,204 16,280 11,934 7,331
2009 4,494 1,238 1,037 1,106 1,037 1,070 3,701 18,949 19,105 15,977 15,233 10,242 7,812
2010 5,804 2,261 1,475 1,173 1,078 1,041 1,481 16,183 16,524 22,802 16,573 13,031 8,344
Average 5,096 2,152 1,521 1,275 1,129 1,037 1,398 11,284 21,718 20,034 17,757 11,257 8,015
Maximum 10,415 4,380 2,634 1,971 1,802 1,697 3,701 22,327 42,839 28,767 30,542 21,863 10,733
Minimum 2,403 1,021 709 619 602 574 609 2,857 12,773 13,169 7,772 4,260 4,912
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Table 5.5-1. Number of microhabitat use measurements by Focus Area and habitat type for all species and life stages observed during the 2013 HSC
surveys of the Middle River Segment of the Susitna River, Alaska.
Species Life Stage
Focus Area1 Habitat Type
FA-
104
FA-
113
FA-
115
FA-
128
FA-
138
FA-
141
FA-
144 NFA Total BW CWP MC SC SS TM TRIB US Total
Chinook FRY 10 0 0 14 14 15 2 2 57 0 0 3 4 28 12 5 5 57
JUV 8 0 2 6 10 5 0 3 34 1 1 4 12 10 0 1 5 34
Chum FRY 4 2 0 5 2 1 0 0 14 0 0 1 7 4 0 1 1 14
JUV 0 0 0 1 0 0 0 1 2 0 0 0 1 1 0 0 0 2
Spawning 1 0 0 36 54 13 45 197 346 0 21 0 135 132 7 0 51 346
Coho FRY 31 10 2 6 4 36 2 7 98 8 0 1 12 23 17 9 28 98
JUV 21 10 15 3 2 1 0 5 57 1 0 0 5 9 1 7 34 57
Spawning 0 0 0 3 0 0 0 0 3 0 0 0 3 0 0 0 0 3
Pink Spawning 0 0 0 0 0 17 0 42 59 0 0 0 0 6 36 17 0 59
Sockeye FRY 12 9 10 19 21 6 0 2 79 0 0 1 18 36 0 3 21 79
JUV 5 2 0 3 4 2 0 1 17 0 0 0 6 9 0 0 2 17
Spawning 0 0 0 44 40 9 72 17 182 0 0 0 73 74 12 7 16 182
Arctic FRY 10 6 11 22 11 35 11 8 114 6 5 7 35 23 17 1 20 114
Grayling JUV 4 3 0 9 3 14 4 4 41 2 6 5 19 6 1 0 2 41
ADULT 0 0 0 0 0 4 0 0 4 0 4 0 0 0 0 0 0 4
Lamprey JUV 1 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 1
Burbot JUV 1 0 0 0 0 1 0 0 2 0 0 2 0 0 0 0 0 2
ADULT 6 1 5 2 2 0 1 0 17 0 0 3 9 0 0 0 5 17
Dolly FRY 1 7 0 0 0 10 0 1 19 2 0 0 0 0 4 10 3 19
Varden JUV 1 0 0 0 1 0 0 0 2 0 0 0 0 0 0 0 2 2
ADULT 0 0 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1
Longnose FRY 7 17 4 1 0 9 1 2 41 3 0 1 14 3 0 8 12 41
Sucker JUV 15 7 5 3 9 7 1 5 52 1 0 6 29 7 0 0 9 52
ADULT 17 8 4 7 13 6 4 12 71 2 0 19 36 9 0 0 5 71
Rainbow FRY 0 2 0 0 0 0 0 0 2 0 0 0 0 0 0 2 0 2
Trout JUV 2 2 0 0 0 1 0 0 5 0 1 0 1 0 0 2 1 5
ADULT 3 0 0 1 0 0 1 1 6 0 0 1 2 1 0 0 2 6
Whitefish FRY 4 5 2 3 12 9 1 4 40 5 0 1 13 12 1 1 7 40
JUV 6 3 2 9 5 8 2 3 38 1 2 3 14 7 0 1 10 38
ADULT 2 3 1 5 6 6 1 4 28 0 5 7 12 0 0 0 4 28
174 97 63 119 120 176 31 65 1433 32 24 65 249 193 53 51 178 1433
Notes:
1 NFA indicates Non-Focus Area. FA-104 (Whiskers Slough), FA-113 (Oxbow 1), FA-115 (Slough 6A), FA-128 (Slough 8A), FA-138 (Gold Creek),
FA-141 (Indian River), FA-144 (Slough 21)
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Table 5.5-2. Number of individual sampling events by Focus Area, habitat type, and sampling session during
2013 HSC sampling in the Middle Susitna River, Alaska.
Focus Area
Number of Sampling
Events Habitat Type1
Number of Sampling
Events Sample Session
Number of Sampling
Events
FA-104
(Whiskers Slough) 47 Backwater 2 June 18-22 12
FA-113
(Oxbow 1) 14 Clearwater Plume 4 July 10-17 44
FA-115
(Slough 6A) 11 Main Channel 30 July 23-30 26
FA-128
(Slough 8A) 36 Side Channel 66 August 6-13 58
FA-138
(Gold Creek) 32 Side Slough 44 August 20-23 18
FA-141
(Indian River) 22 Upland Slough 40 September 10-17 39
FA-144
(Slough 21) 23 Tributary Mouth 9 September 24-29 10
Outside Focus Area 25 Tributary 12
Notes:
1 Habitat types defined in ISR Study 9.9.
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Table 5.5-3. Number of HSC microhabitat use observations by sampling session for each species and life
stage collected during the summer 2013 sampling of the Middle Segment of the Susitna River, Alaska.
Species Life Stage Jun 18-22 Jul 10-17 Jul 23-30 Aug 6-13 Aug 20-27 Sep 10-16 Sep 24-30 Total
Chinook FRY 0 12 18 23 0 4 0 57
JUV 9 3 2 12 4 4 0 34
Chum FRY 6 5 3 0 0 0 0 14
JUV 0 0 0 2 0 0 0 2
Spawning 0 0 0 9 52 185 101 346
Coho FRY 1 5 26 23 19 24 0 98
JUV 4 3 12 13 16 9 0 57
Spawning 0 0 0 0 0 0 3 3
Pink Spawning 0 0 0 53 6 0 0 59
Sockeye FRY 17 24 9 12 9 8 0 79
JUV 2 0 0 0 5 10 0 17
Spawning 0 0 0 6 6 106 64 182
Arctic FRY 0 23 46 34 6 5 0 114
Grayling JUV 0 3 4 20 6 8 0 41
ADULT 0 2 0 2 0 0 0 4
Lamprey JUV 0 0 0 0 0 1 0 1
Burbot JUV 1 0 0 0 1 0 0 2
ADULT 3 4 1 8 0 1 0 17
Dolly FRY 0 0 17 0 1 1 0 19
Varden JUV 0 0 0 1 0 1 0 2
ADULT 0 1 0 0 0 0 0 1
Longnose FRY 0 1 5 4 23 8 0 41
Sucker JUV 5 11 5 14 12 5 0 52
ADULT 7 14 3 31 9 7 0 71
Rainbow FRY 0 0 2 0 0 0 0 2
Trout JUV 0 0 2 2 0 1 0 5
ADULT 1 1 0 4 0 0 0 6
Whitefish FRY 0 10 8 11 10 1 0 40
JUV 2 8 2 14 7 5 0 38
ADULT 0 10 1 15 0 2 0 28
Total 58 140 166 313 192 396 168 1433
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Table 5.5-4. Number of microhabitat availability measurements by Focus Area and habitat type collected
during the 2013 field season for the Middle Segment of the Susitna River, Alaska.
Focus Area
Habitat Type
Total BW CWP MC SC SS TM TRIB US
FA-104
(Whiskers Slough)
220 105 206
90 126 747
FA-113
(Oxbow 1)
60 104
31 25 220
FA-115
(Slough 6A)
20 25
100 145
FA-128
(Slough 8A)
140 219 135 35
57 586
FA-138
(Gold Creek)
75 124 241
62 502
FA-141
(Indian River) 24 75 100 30
32 30 65 356
FA-144
(Slough 21)
110 184 42
30 366
Outside Focus Areas 18 59 135 39 34 15 75 375
Total 24 93 784 926 663 101 166 540 3297
Notes:
BW-backwater, CWP-clearwater plume, MC-main channel, SC-side channel, SS-side slough, TM-tributary mouth,
Trib-tributary
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Table 5.5-5. Summary statistics for water quality variables collected during summer 2013 in habitat units
within the Middle Segment of the Susitna River, Alaska.
Statistic Main Channel Side Channel Backwater Clearwater Plume Side Slough Upland Slough Tributary Tributary Mouth Total
Temperature (°C)
Max 17.3 16.7 13.2 14.9 17.9 26.7 17.1 16.4 26.7
Mean 12.5 10.4 10.3 11.2 9.4 10.4 13.1 10.4 10.9
Min 7.7 3.2 7.5 7.1 4.6 3.6 7.8 5.4 3.2
Count 784 926 24 93 663 540 166 101 3297
Conductivity (uS)
Max 173 258 126 95 328 381 78 253 381
Mean 143 159 96 69 179 136 44 128 146
Min 100 43 28 19 28 23 24 66 19
Count 784 926 24 93 663 540 166 101 3297
Dissolved Oxygen (mg/L)
Max 12.5 13.0 10.5 11.8 12.4 12.8 11.8 12.7 13.0
Mean 11.0 10.7 9.5 10.8 10.0 8.1 10.3 10.8 10.3
Min 10.1 6.7 8.6 8.8 5.3 3.4 8.2 7.9 3.4
Count 685 861 24 93 654 536 166 110 3129
Turbidity (NTU)
Max 962 528 89 21 95 312 3 10 962
Mean 209 73 49 8 7 28 1 3 77
Min 1 1 10 2 1 1 0 1 0
Count 784 926 24 93 663 540 166 101 3297
VHG (mm)
Max 40 80 70 10 200 190 62 75 200
Mean -8 14 24 4 20 31 6 -20 11
Min -95 -60 0 -5 -75 -32 -35 -120 -120
Count 784 926 24 93 663 540 166 101 3297
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Table 5.5-6. Number of water quality observations by metric bin and habitat type collected during summer
2013 HSC surveys in the Middle Segment of the Susitna River, Alaska.
Metric Bin
Main
Channel
Side
Channel Backwater
Clearwater
Plume
Side
Slough
Upland
Slough Tributary
Tributary
Mouth Total
Temperature (°C)
0-4.9 0 54 0 0 30 27 0 0 111
5.0-9.9 195 364 12 15 365 198 18 27 1194
10.0-14.9 396 410 12 78 230 269 103 64 1562
15.0-19.9 193 98 0 0 38 37 45 10 421
20.0-24.9 0 0 0 0 0 9 0 0 9
Total 784 926 24 93 663 540 166 101 3297
Conductivity (uS)
0-86 0 41 3 70 123 126 166 56 585
87-173 769 632 21 23 246 262 0 20 1973
173-258 15 253 0 0 75 89 0 25 457
259-344 0 0 0 0 219 46 0 0 265
>344 0 0 0 0 0 17 0 0 17
Total 784 926 24 93 663 540 166 101 3297
Dissolved Oxygen (mg/L)
0-4.9 0 0 0 0 0 35 0 0 35
5.0-9.9 0 146 18 14 241 373 42 20 854
10.0-14.9 693 652 6 79 339 76 124 71 2040
≥15 0 0 0 0 3 0 0 0 3
NA 91 128 0 0 80 56 0 10 365
Total 784 926 24 93 663 540 166 101 3297
Turbidity (NTU)
≤30 220 490 12 93 630 445 166 101 2157
>30 564 436 12 0 33 95 0 0 1140
Total 784 926 24 93 663 540 166 101 3297
VHG (mm)
<(-5) 305 73 0 0 22 21 29 55 505
(-5) – (+5) 399 275 9 48 222 108 87 34 1182
>5 80 578 15 27 419 411 50 12 1592
NA 0 0 0 18 0 0 0 0 18
784 926 24 93 663 540 166 101 3297
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Table 5.5-7. Total number of fish captured by species and life stage during daytime and nighttime
electrofishing surveys conducted in FA-104 (Whiskers Slough) and FA-128 (Slough 8A) in March and April
2013.
Site
Survey
Date
Habitat
Type1
Area
Surveyed
(ft2)
Capture totals, by species
Total
Count
Chinook,
Juvenile
Coho,
Juvenile
Sculpin sp.,
Juvenile, adult
FA-104-WSL-20 24-Mar SS 12502 0 0 8 8
FA-104-WSC-10 24-Mar SC 4256 0 0 0 0
FA-104-SL3B-10 24-Mar SC 3432 1 0 4 5
FA-104-SL3A-71 24-Mar US 4455 1 0 35 36
25-Mar2 4455 12 3 35 50
FA-128-SL8A-10
22-Mar
SS
14850 0 0 1 1
22-Mar2 14850 3 0 0 3
9-Apr 18150 2 0 8 10
FA-128-SC8A-28 9-Apr SC 4356 0 0 0 0
9-Apr2 4356 7 0 6 13
FA-128-SSC-20 10-Apr SC 5610 0 0 0 0
10-Apr2 5610 0 0 0 0
FA-128-US2-10 22-Mar US 240 0 0 0 0
22-Mar2 240 1 0 0 1
Notes:
1 SS = Side slough, SC = Side Channel, US = Upland Slough; habitat designations are based on 2012 Middle
Susitna River remote line habitat mapping (HDR 2013).
2 Survey was conducted at night.
Table 5.5-8. Total number of HSC observations recorded during electrofish sampling in March and April
2013 by species and life stage.
Species Life stage
FA-104
(Whiskers Slough)
FA-128
(Slough 8A) Total
Chinook salmon Juvenile 14 12 26
Coho salmon Juvenile 3 0 3
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Table 5.5-9. Number of Hess, algae, and snag samples collected with associated depth (D), velocity (V), and substrate composition (Sub) measurements
for 2013 sampling during three index events (Spr= Spring, Sum=Summer, Fall) in the Middle and Lower River Segments of the Susitna River for the
River Productivity Study.
Site Macro-habitat Type
Hess Samples (D, V, Sub) Algae Samples (D, V) Snag Samples (D, V, Sub)
Spr Sum Fall Post-Storm Total Spr Sum Fall Post-Storm Total Spr Sum Fall Post-Storm Total
RP-184-1 Tributary Mouth 5 4 5 14 25 20 25 70 5 2 3 10
RP-184-2 Side Channel 5 5 5 15 25 25 25 75 1 1
RP-184-3 Main Channel 5 5 5 15 25 25 25 75 RP-173-1 Tributary Mouth 5 5 5 15 25 25 25 75 2 3 1 6
RP-173-2 Main Channel 5 5 5 15 25 25 25 75 RP-173-3 Side Channel 5 5 5 15 25 25 25 75 3 3
RP-173-4 Side Slough 5 5 2 5 17 25 25 25 25 100 1 2 5 8
RP-141-1 Tributary Mouth 5 5 5 15 25 25 25 75 3 5 5 13
RP-141-2 Side Channel 5 5 10 25 25 25 75 5 1 6
RP-141-3 Mult Split Main
Channel 5 5 5 15 25 25 25 75
RP-141-4 Upland Slough 5 4 3 12 25 25 25 75 3 4 5 12
RP-104-1 Side Slough 5 5 5 15 25 25 25 75 2 5 5 12
RP-104-2 Side Slough 5 5 2 5 17 25 25 25 25 100 3 5 5 5 18
RP-104-3 Main Channel 5 5 5 15 25 25 25 75 RP-104-4 Upland Slough 25 25 50 5 5 3 13
RP-104-5 Side Channel 5 5 5 15 25 25 25 75 2 5 7
RP-81-1 Upland Slough 5 5 25 25 25 75 5 2 5 12
RP-81-2 Tributary Mouth 5 5 5 15 25 25 25 75 5 5 5 15
RP-81-3 Split Main Channel 5 5 5 15 25 25 25 75 2 2 4
RP-81-4 Side Channel 5 5 5 15 25 25 25 75 0 5 5 10
RP-TKA-1 Side Channel 5 5 5 15 25 25 25 75 RP-TKA-2 Upland Slough 25 25 25 75 RP-TKA-3 Side Slough 5 5 5 15 25 25 25 75 Totals 100 98 92 10 300 575 545 575 50 1745 36 54 55 5 150
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Table 5.5-10. Source and projected availability of water quality and fish abundance data needed for
completion of an evaluation of relationships between fish abundance and water quality within Middle River
Segment Focus Areas.
Variable Source/Study
Availability
(QA/QC’d data)
Water Temperature Water Quality, River Productivity, Groundwater, FDA, HSC Q4 2013
Dissolved Oxygen Water Quality, River Productivity, FDA, HSC Q4 2013
Conductivity Water Quality, River Productivity, FDA, HSC Q4 2013
pH Water Quality Q4 2013
Surface flow and groundwater
exchange flux Groundwater Q1 2014
Intergravel water temp. Groundwater Q1 2014
Macronutrients Water Quality Q1 2014
Dissolved Organic Carbon Water Quality Q1 2014
Alkalinity Water Quality Q1 2014
Chlorophyll-a Water Quality Q1 2014
Fish Distribution/Abundance FDA Q1 2014
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10. FIGURES
[See separate file for Figures.]
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APPENDIX A: HYDROLOGIC METHODS
[See separate file for Appendix.]
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APPENDIX B: BIOLOGICAL CUES STUDY
[See separate file for Appendix.]
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APPENDIX C: MOVING BOAT ADCP MEASUREMENTS
[See separate file for Appendix.]
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APPENDIX D: GINA INITIAL STUDY REPORT 8.5 DATA FILES
[See separate file for Appendix.]
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APPENDIX E: TRIBUTARY GAGING SITE SCHEMATICS
[See separate file for Appendix.]
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APPENDIX F: TRIBUTARY GAGING REPRESENTATIVE SITE PHOTOS
[See separate file for Appendix.]
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APPENDIX G: HSC HISTOGRAM PLOTS
[See separate file for Appendix.]
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APPENDIX H: PERIODICITY TABLES
[See separate file for Appendix.]
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APPENDIX I: LOWER RIVER HYDRAULIC MODEL CALIBRATION
[See separate file for Appendix.]