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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
SuWa 236
Fish and aquatics instream flow study (Study 8.5), 2013-2014 instream flow
winter studies, technical memorandum
Author(s) – Personal:
Author(s) – Corporate:
R2 Resource Consultants, Inc.
AEA-identified category, if specified:
September 17, 2014 technical memorandum filings
AEA-identified series, if specified:
Series (ARLIS-assigned report number): Existing numbers on document:
Susitna-Watana Hydroelectric Project document number 236
Published by: Date published:
[Anchorage, Alaska : Alaska Energy Authority, 2014] September 2014
Published for: Date or date range of report: Alaska Energy Authority
Volume and/or Part numbers:
Final or Draft status, as indicated:
Attachment H
Document type: Pagination:
Technical memorandum v, 57 p.
Related work(s): Pages added/changed by ARLIS:
Cover letter to this report: Susitna-Watana Hydroelectric
Project, FERC Project no. 14241-000; Initial filing of September
2014 technical memoranda. (SuWa 228)
Attachments A-G and I-J (SuWa 229-235 and 237-238)
Fish and aquatics instream flow study (Study 8.5), 2013-2014
instream flow winter studies, technical memorandum. (SuWa
272) This document contains the replacement pages.
Added cover letter.
Pages 38-40 (containing figures
2-4) were replaced by corrected
pages issued in SuWa 272.
Those replacement pages are
dated December 2014, but are
numbered 2-4 as they are in
SuWa 272.
Notes:
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
September 17, 2014
Ms. Kimberly D. Bose
Secretary
Federal Energy Regulatory Commission
888 First Street, N.E.
Washington, D.C. 20426
Re:Susitna-Watana Hydroelectric Project, Project No. 14241-000
Initial Filing of September 2014 Technical Memoranda
Dear Secretary Bose:
By letter dated January 28, 2014, the Federal Energy Regulatory Commission
(Commission or FERC) extended the procedural schedule for the preparation and review
of the Initial Study Report (ISR) for the proposed Susitna-Watana Hydroelectric Project,
FERC Project No. 14241 (Project).1 In particular, the Commission’s January 28 letter
established a deadline of June 3, 2014 for the Alaska Energy Authority (AEA) to file the
ISR, and provided a 120-day period for licensing participants to review the ISR prior to
the ISR meetings, which are scheduled to begin the week of October 13.2 The purpose of
this filing is to provide several technical memoranda to Commission Staff and licensing
participants prior to the ISR meetings.
As required by the Commission’s January 28 letter, AEA filed the ISR with the
Commission on June 3. Among other things, the ISR detailed AEA’s planned work
during the 2014 field season.3 As AEA was preparing this 2014 work plan, it recognized
that data gathered during the 2014 field season, together with other study work conducted
prior to the October 2014 ISR meetings,could assist Commission Staff, AEA, and other
licensing participants in developing the Project’s licensing study program for 2015. For
this reason, the ISR provided for AEA to prepare certain technical memoranda and other
information based on 2014 work.
AEA recognizes that Commission Staff and licensing participants need a
reasonable amount of time prior to the ISR meetings to review this additional
information. AEA and licensing participants consulted with Commission Staff on this
1 Letter from Jeff Wright, Federal Energy Regulatory Commission, to Wayne Dyok, Alaska Energy
Authority, Project No. 14241-000 (issued Jan. 28, 2014)[hereinafter, “January 28 letter”].
2 The full schedule for the ISR meetings appears in Section 1.5 of the ISR, as well as on AEA’s
licensing website, http://www.susitna-watanahydro.org/meetings/.
3 E.g., Initial Study Report §1.3 & Table 3, Project No. 14241-000 (filed June 3, 2014) [hereinafter,
“ISR”].
2
matter, and Staff directed that any additional information should be filed with the
Commission and made available to licensing participants no later than 15 days prior to
the ISR meetings, consistent with the typically applicable deadline under the
Commission’s Integrated Licensing Process regulations.4
With this letter, AEA is filing and distributing the first set of technical
memoranda and other information generated during the 2014 study season, as described
below. As part of its continued implementation of the study plan, AEA expects to file
certain additional technical memoranda prior to October 1, 2014, in accordance with
Commission Staff direction.
This first set of technical memoranda and other information consists of the
following:
Attachment A: Proposal to Eliminate the Chulitna Corridor from Further
Study. As explained in the ISR, throughout the licensing process AEA has
continually evaluated its proposal for Project development based on
environmental review, technical feasibility, practical considerations, and other
factors. As part of this iterative process, AEA notified the Commission and
licensing participants in the ISR that it was evaluating whether to continue
study of the Chulitna Corridor.5 Attachment A details AEA’s conclusion that
development of the Chulitna Corridor is not a reasonable alternative, and
therefore AEA proposes to eliminate the corridor from further study. AEA
seeks any comments or information on this proposal from federal and state
resource agencies and other participants in the licensing process.
Attachment B: Ice Processes in the Susitna River Study (Study 7.6),Detailed
Ice Observations October 2013 –May 2014 Technical Memorandum. The
ISR indicated that AEA would provide a summary of the 2014 break-up
observations.6 This technical memorandum describes all field activities and
observations between October 16, 2013 and May 15, 2014 for the Ice
Processes in the Susitna River Study (Study 7.6).
Attachment C: Study of Fish Distribution and Abundance in the Upper
Susitna River (Study 9.5), Proposed 2015 Modifications to Fish Distribution
and Abundance Study Plan Implementation Technical Memorandum. Based
on AEA’s experience in implementing the study plan for the Study of Fish
Distribution and Abundance in the Upper Susitna River (Study 9.5)during
2014, this technical memorandum proposes to continue certain modifications
to the implementation of this study during 2015.
4 See 18 C.F.R. §5.15(c)(2).
5 See ISR, ISR Overview §1.4.
6 See id., Ice Processes in the Susitna River Study,Study Plan 7.6, Part C §7.2.
3
Attachment D: Study of Fish Distribution and Abundance in the Middle and
Lower Susitna River Study (Study 9.6), 2013-2014 Winter Fish Study
Technical Memorandum. At the time the ISR was filed, AEA was still in the
process of conducting data entry, quality control, and analysis of winter
sampling for this study. AEA reported in the ISR that it would develop plans
for completing this study in a technical memorandum to be filed with the
Commission.7 This technical memorandum fulfills this commitment and sets
forth AEA’s proposal for winter efforts, including proposed methodologies
and modifications.
Attachment E: Characterization and Mapping of Aquatic Habitats (Study
9.9), 2013 and 2014 Aquatic Habitat Mapping Field Season Completion
Progress Technical Memorandum. In the ISR, AEA reported that its 2014
activities for the Characterization and Mapping of Aquatic Habitats Study
(Study 9.9) would consist of various ground-truthing surveys and collection of
habitat information for the 12 lakes within the potential reservoir inundation
zone.8 This technical memorandum reports on these activities.
Attachment F: Eulachon Run Timing, Distribution, and Spawning in the
Susitna River (Study 9.16), 2015 Proposed Eulachon Spawning Habitat Study
Modifications Technical Memorandum.After reviewing the 2013 and 2014
results from the Cook Inlet Beluga Whale Study (Study 9.17) and discussing
the results with the National Marine Fisheries Service, AEA has determined
that additional data are needed regarding eulachon spawning habitats. This
technical memorandum describes a proposed modification to the Study of
Eulachon Run Timing, Distribution and Spawning in the Susitna River (Study
9.16)to include an assessment of eulachon spawning habitats.
Attachment G: Fish and Aquatics Instream Flow Study (Study 8.5),
Evaluation of Relationships between Fish Abundance and Specific
Microhabitat Variables Technical Memorandum. Consistent with the
Commission’s study plan determination,9 this technical memorandum
provides a detailed evaluation of the comparison of fish abundance measures
with specific microhabitat variable measurements where sampling overlaps.
This memorandum is used to determine whether a relationship between a
specific microhabitat variable and fish abundance is evident.
Attachment H: Fish and Aquatics Instream Flow Study (Study 8.5), 2013-
2014 Instream Flow Winter Studies Technical Memorandum.In the ISR,
AEA reported that it would distribute its finding concerning the 2013-2014
7 See id., Study of Fish Distribution and Abundance in the Middle and Lower Susitna River Study,
Study Plan 9.6, Part C §7.1.2.5.
8 See id., Characterization and Mapping of Aquatic Habitats, Study Plan 9.9, Part C § 7.1.
9 See Study Plan Determination on 14 Remaining Studies for the Susitna-Watana Hydroelectric Project,
Appendix B at B-84 to B-86, Project No. 14241-000 (issued Apr. 1, 2013).
4
winter activities in 2014.10 This technical memorandum describes the
methods applied, and data and information collected, as part of the Instream
Flow Study 2013-2014 winter studies.
Attachment I: Geomorphology Study (Study 6.5), Susitna River Historical
Cross Section Comparison (1980s to Current) Technical Memorandum. As
specified in Revised Study Plan Section 6.5.4.1.2.3, this technical
memorandum describes changes within the main and side channels of the
Susitna River by comparing historical survey data from the 1980s with survey
data from the current Project.
Attachment J: Geomorphology Study (Study 6.5), 2014 Update of Sediment-
Transport Relationships and a Revised Sediment Balance for the Middle and
Lower Susitna River Segments Technical Memorandum. The purpose of this
technical memorandum is to update the sediment load rating curves and
preliminary estimates of the overall sediment balance in the Middle and
Lower River segments under pre-Project conditions that were initially
provided in “Development of Sediment-Transport Relationships and an Initial
Sediment Balance for the Middle and Lower Susitna River Segments,” (Tetra
Tech, Inc. 2013a). This update is based on additional data collected by the
U.S. Geological Survey in 2012 and 2013.
AEA appreciates the opportunity to provide this additional information to the
Commission and licensing participants, which it believes will be helpful in determining
the appropriate development of the 2015 study plan as set forth in the ISR. If you have
questions concerning this submission please contact me at wdyok@aidea.org or (907)
771-3955.
Sincerely,
Wayne Dyok
Project Manager
Alaska Energy Authority
Attachments
cc: Distribution List (w/o Attachments)
10 See ISR, Fish and Aquatics Instream Flow Study, Study Plan 8.5, Part C §7.5.2.
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Fish and Aquatics Instream Flow Study
(Study 8.5)
2013-2014 Instream Flow Winter Studies
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
R2 Resource Consultants, Inc.
September 2014
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i September 2014
TABLE OF CONTENTS
1. Introduction ........................................................................................................................1
1.1. Project Description .............................................................................................1
1.2. Study Background ..............................................................................................2
1.2.1. Ice Formation .................................................................................. 2
1.2.2. Influence and Importance of Groundwater ..................................... 3
1.2.3. Salmonid Egg Incubation and Survival During the Winter ............ 4
1.2.4. Winter Habitat Conditions for Juvenile and Adult Fish ................. 6
1.2.5. Summary ......................................................................................... 7
2. Study Objectives.................................................................................................................7
3. Study Area ..........................................................................................................................8
4. Methods ...............................................................................................................................8
4.1. Water Surface Elevations ...................................................................................8
4.2. Water Quality .....................................................................................................9
4.3. Fish Observations.............................................................................................11
4.4. Deviations from Study Plan .............................................................................11
5. Results ...............................................................................................................................12
5.1. Water Surface Elevation ..................................................................................12
5.1.1. FA-104 (Whiskers Slough) ........................................................... 12
5.1.2. FA-128 (Slough 8A) ..................................................................... 12
5.1.3. FA-138 (Gold Creek) .................................................................... 13
5.2. Water Quality ...................................................................................................13
5.2.1. FA-104 (Whiskers Slough) ........................................................... 13
5.2.2. FA-128 (Slough 8A) ..................................................................... 14
5.2.3. FA-138 (Gold Creek) .................................................................... 16
5.3. Fish Observations.............................................................................................17
6. Discussion and Conclusion ..............................................................................................17
6.1. Water Surface Elevation ..................................................................................18
6.2. Water Quality ...................................................................................................19
6.3. Fish Observations.............................................................................................21
7. Plans for 2015 ...................................................................................................................22
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii September 2014
8. References .........................................................................................................................23
9. Tables ................................................................................................................................29
10. Figures ...............................................................................................................................36
LIST OF TABLES
Table 1. The period of data collection at continuous water level, water quality and barometric
pressure monitoring sites in FA-104 (Whiskers Slough), FA-128 (Slough 8A) and FA-138
(Gold Creek) for 2013-2014 IFS winter studies. .................................................................. 30
Table 2. Instantaneous measurements of surface and groundwater temperature, specific
conductance, dissolved oxygen concentration, and ice thickness at sites in FA-104
(Whiskers Creek), FA-128 (Slough 8A), and FA-138 (Gold Creek) during February and
March 2014. Surface water measurements were recorded at mid-column water depth and
groundwater was measured approximately 20 cm below the substrate surface at intergravel
and near the surface at groundwater wells and bank seep locations. .................................... 31
Table 3. Total number of fish captured by species and lifestage during daytime and nighttime
electrofishing surveys conducted in FA-104 (Whiskers Slough), FA-128 (Slough 8A), FA-
138 (Gold Creek), and FA-141 (Indian River) in February, March, and April 2014.
Nighttime surveys are italicized. ........................................................................................... 33
Table 4. Total number of HSC observations recorded during electrofish sampling in February,
March, and April 2014 by fish species and lifestage. ........................................................... 35
LIST OF FIGURES
Figure 1. Location of Focus Areas used for 2013-2014 IFS winter data collection. ................... 37
Figure 2. Locations of 2013-2014 winter sites for continuous and instantaneous water quality
monitoring, water level monitoring, and fish sampling in FA-104 (Whiskers Slough). ...... 38
Figure 3. Locations of 2013-2014 winter sites for continuous and instantaneous water quality
monitoring, water level monitoring, and fish sampling in FA-128 (Slough 8A). ................ 39
Figure 4. Locations of 2013-2014 winter sites for continuous and instantaneous water quality
monitoring, water level monitoring, and fish sampling in FA-138 (Gold Creek). ............... 40
Figure 5. Comparison of change in normalized water surface elevation among continuous
monitoring sites in FA-104 (Whiskers Slough) during September 2013 through June 2014.
Elevations were normalized to zero on October 1, 2013. ..................................................... 41
Figure 6. Comparison of change in normalized water surface elevation among continuous
monitoring sites in FA-128 (Slough 8A) during September 2013 through April 2014.
Elevations were normalized to zero on September 30, 2013. ............................................... 42
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii September 2014
Figure 7. Comparison of change in normalized water surface elevation among continuous
monitoring sites in FA-138 (Gold Creek) during September 2013 through April 2014.
Elevations were normalized to zero on September 30, 2013. ............................................... 43
Figure 8. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Susitna River main channel (104-MC-40) and Whiskers Side Channel (104-WSC-10)
continuous monitoring sites in FA-104 (Whiskers Slough) during September 2013 - June
2014. Water elevations were normalized to zero on October 1, 2013. ................................ 44
Figure 9. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Whiskers Side Channel (104-WSC-30) and Whiskers East Side Channel (104-WESC-10)
continuous monitoring sites in FA-104 (Whiskers Slough) during September 2013 - June
2014. Water elevations were normalized to zero on October 1, 2013. ................................ 45
Figure 10. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at upland slough (104-SL3A-70) and side channel (104-SL3B-10) continuous monitoring
sites in FA-104 (Whiskers Slough) during September 2013 - June 2014. Water elevations
were normalized to zero on October 1, 2013. ....................................................................... 46
Figure 11. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Whiskers Creek (104-WC-10) and Whiskers Slough (104-WSL-20) continuous
monitoring sites in FA-104 (Whiskers Slough) during September 2013 - June 2014. Water
elevations were normalized to zero on October 1, 2013. ...................................................... 47
Figure 12. Instantaneous measurements of surface water temperature and specific conductance
recorded at sites in FA-104 (Whiskers Slough) during February and March 2014, by
macrohabitat type. ................................................................................................................. 48
Figure 13. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Susitna River main channel (128-MC-10) and Side Channel 8A (128-SC8A-25)
continuous monitoring sites in FA-128 (Slough 8A) during September 2013 - April 2014.
Water elevations were normalized to zero on September 30, 2013. ..................................... 49
Figure 14. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Slough 8A (128-SL8A-40 and 128-SL8A-15) continuous monitoring sites in FA-128
(Slough 8A) during September 2013 - April 2014. Water elevations were normalized to
zero on September 30, 2013. ................................................................................................. 50
Figure 15. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Upland Slough 2 (128-US2-15) and Upland Slough 1 (128-US1-10) continuous
monitoring sites in FA-128 (Slough 8A) during September 2013 - April 2014. Water
elevations were normalized to zero on September 30, 2013. ................................................ 51
Figure 16. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv September 2014
at Skull Creek (128-SC-05) and Slough A (128-SLA-20) continuous monitoring sites in FA-
128 (Slough 8A) during September 2013 - April 2014. Elevations were normalized to zero
on September 30, 2013. ........................................................................................................ 52
Figure 17. Continuous intergravel dissolved oxygen concentration and water temperature data
recorded approximately 20 cm (7.9 in) below the substrate surface at in FA-128 (Slough
8A; Site SL8A-40) and during September 2013 - April 2014. ............................................. 53
Figure 18. Instantaneous measurements of surface water temperature and specific conductance
recorded at sites in FA-128 (Slough 8A) during February and March 2014, by macrohabitat
type. ....................................................................................................................................... 53
Figure 19. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Susitna River main channel (138-MC-10) and Upper Side Channel 11 (138-USC11-09)
continuous monitoring sites in FA-138 (Gold Creek) during September 2013 - March 2014.
Water elevations were normalized to zero on September 30, 2013. ..................................... 54
Figure 20. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Slough 11 (138-SL11-06 and 138-SL11-04) continuous monitoring sites in FA-138 (Gold
Creek) during September 2013 - March 2014. Water elevations were normalized to zero on
September 30, 2013. ............................................................................................................. 55
Figure 21. Water temperature recorded above the substrate surface and at intergravel depths of 5
cm (2 in), 20 cm (7.9 in), and 35 cm (13.8 in) relative to normalized water surface elevation
at Slough 11 continuous monitoring site 138-SL11-20 in FA-138 (Gold Creek) during
September 2013 - March 2014. Elevations were normalized to zero on September 30, 2013.
............................................................................................................................................... 56
Figure 22. Continuous intergravel dissolved oxygen concentration and water temperature data
recorded approximately 20 cm (7.9 in) below the substrate surface at FA-138 (Gold Creek;
Site 138-SL11-04) during September 2013 - April 2014. .................................................... 56
Figure 23. Instantaneous measurements of surface water temperature and specific conductance
recorded at sites in FA-138 (Gold Creek) during February and March 2014, by macrohabitat
type. ....................................................................................................................................... 57
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v September 2014
LIST OF ACRONYMS AND SCIENTIFIC LABELS
Abbreviation Definition
AEA Alaska Energy Authority
ARIS Adaptive Resolution Imaging Sonar
°C Degrees centigrade
cfs Cubic feet per second
Cm Centimeter
FA Focus Area
FDA Fish Distribution and Abundance
FERC Federal Energy Regulatory Commission
fps Feet per second
mg/L Milligrams per liter
HSC Habitat suitability criteria
HSI Habitat suitability indices
IFS Instream Flow Study
ISR Initial Study Report
MW Megawatts
NTU Nephelometric turbidity units
PRM Project River Mile
RSP Revised Study Plan
TM Technical Memorandum
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 September 2014
1. INTRODUCTION
1.1. Project Description
The Alaska Energy Authority (AEA) is preparing a License Application that will be submitted to
the Federal Energy Regulatory Commission (FERC) for the Susitna-Watana Hydroelectric
Project (Project) using the Integrated Licensing Process. The Project is located on the Susitna
River, an approximately 300-mile long river in the Southcentral Region of Alaska. The Project’s
dam site will be located at Project River Mile (PRM) 187.1. As currently envisioned, the Project
would include a large dam with an approximately 24,000-acre, 42-mile long reservoir. The
Project construction and operation would have an effect on the flows downstream of the dam
site, the degree of which will ultimately depend on final Project design and operations.
The Project may contain up to four turbines capable of generating 150-200 megawatts (MW) of
power each such that the total power capacity could be 800 MW. The Project reservoir is
expected to fill during the summer months (May – August), when runoff from snow melt and
rainfall is greatest, to maximize power generation capability during the winter months (October –
April) when energy demand is high. As a result, seasonal changes to Susitna River streamflow
conditions during Project operations may include lower discharges during the summer reservoir
refill period and higher discharges during the winter relative to current hydrologic conditions. In
addition to these seasonal changes, the Project may be operated in a load-following mode to meet
energy demands on an hourly basis. During load-following operations, the amount of water
released from the reservoir would cycle daily according to energy demands such that higher
volumes would be released during peak-load hours relative to off-peak hours. Seasonal and
daily/hourly changes to Susitna River hydrology would influence downstream resources and
processes, including resident and anadromous fish species and aquatic habitats. As a result,
AEA developed and the FERC approved (FERC 2013) a detailed Instream Flow Study (IFS)
plan (contained as Section 8.5 in the December 14, 2012 Revised Study Plan [RSP]; see AEA
2012) designed to evaluate the potential effects of Project operations.
One element of the IFS plan pertains to the completion of winter studies designed to assess
patterns of fish habitat use under winter conditions including under ice as well as in open-water
leads influenced by groundwater inflow (RSP Section 8.5.4.5.1.2.1). Companion winter studies
were also specified in the RSP as part of the Fish Distribution and Abundance (FDA) study
under the Fish Program (RSP Section 9.6.4.5) and under the Groundwater (GW) Study (RSP
Section 7.5.4.7) (AEA 2012). The winter period is an ecologically important time for salmonids
in that streamflows are typically at their lowest, relegating fish to areas suitable as overwintering
habitats. The winter period is also the time when salmonid embryos are developing and alevins
hatch and remain within the protective confines of the gravel until the ice-free period when
emergence occurs. The winter studies, in conjunction with the Ice Processes Study (RSP Section
7.6) are designed to provide data and information that will be used to first characterize existing
conditions that occur during the winter period and then, via modeling and data analysis, evaluate
how project operations may influence those conditions and associated fish and fish habitats. The
RSP specified two separate field efforts for these studies including an initial pilot effort during
the winter of 2012-2013 followed by an expanded effort during the winter of 2013-2014. The
ISR specified continuation of winter studies in 2014-2015 in coordination with FDA and GW
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 September 2014
(ISR Study 8.5, Section 7.5.1). This Technical Memorandum (TM) describes the methods
applied, and data and information collected, as part of the IFS 2013-2014 winter studies. Results
of the 2013-2014 winter studies for FDA are presented in a separate TM (AEA 2014b). The
results of the 2012-2013 FDA winter studies were included as Appendix C of ISR Study 9.6
(AEA 2014); results of the 2012-2013 IFS winter studies were included as Appendix L of ISR
Study 8.5 (AEA 2014). The results of those two studies provided information useful for
developing the 2013-2014 expanded winter programs for FDA and IFS.
1.2. Study Background
The Susitna River is a large glacial river that exhibits large hydrologic changes at hourly, daily,
and seasonal temporal scales. Susitna River discharge is typically the highest during the
snowmelt period in spring and early summer (June – August) and large, short-term fluctuations
in flow volumes often occur during summer in response to air temperature changes and
precipitation events. Mean monthly Susitna River streamflow for June, July, and August during
water years 1950 – 2010 ranged between 21,430 – 26,290 cfs (USGS Gold Creek gage
#15292000) (Curran 2012). During the open-water period, Susitna River streamflow is fed
primarily by surface and glacial runoff and water turbidity levels are high (> 200 nephelometric
turbidity units [NTU]) due to suspended glacial silt. Susitna River discharge levels typically
decline during September through November and are lowest during December through April
when the channel is largely ice covered. Mean monthly Susitna River streamflow for December
through April during water years 1950 – 2010 ranged between 1,303 – 1,893 cfs (USGS Gold
Creek gage #15292000) (Curran 2012). Winter streamflow is fed primarily by groundwater and
consequently discharge is stable and water turbidity is low (<10 NTU).
1.2.1. Ice Formation
Ice formation on the Susitna River occurs in an upstream direction from Cook Inlet and is
typically initiated by frazil ice, which is fine ice particles suspended in the water column and
formed in super cooled turbulent water (Labelle 1984, Brown et al. 2011). Jams of frazil ice
form across the river channel and lead to the formation of solid river ice. Ice process surveys
conducted in the Susitna River in the 1980s and in 2012 indicated the start of frazil ice
generation occurred in the Upper Susitna River in mid-September and early October, while the
upstream progression of solid river ice cover in the Middle Susitna River extended from mid-
November through mid-January (Labelle 1984, Trihey & Associates and Entrix 1985, HDR
2014). As river ice forms, the river channel becomes occluded by solid ice which causes the
river stage to increase upstream of the leading edge of ice cover. This process is termed staging.
During 1980s studies, the level of staging was estimated to be greater than four feet in portions
of the Middle Susitna River such that winter water surface levels were equivalent to summer
water levels (Trihey 1982, Labelle 1984, HDR 2014). Average ice thickness in the Susitna River
main channel at RM 120.6 (PRM 124.1) in winter ranged between 1.9 – 10.4 feet during the
years 1980 – 1984 (Labelle 1984). Although nearly all of the Middle Susitna River is ice
covered for portions of winter, open leads caused by water current (velocity lead) or warm water
(thermal lead) derived from groundwater typically remain ice-free throughout winter. Many
open leads mapped during ice surveys in the 1980s and in 2012 and 2013 were associated with
side sloughs, upland sloughs, and tributary mouths with localized groundwater sources (Labelle
1984, HDR 2014).
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 3 September 2014
1.2.2. Influence and Importance of Groundwater
Groundwater sources are an important aspect of Susitna River winter hydrology in terms of
creating flow in habitats otherwise disconnected from the Susitna River main channel and
maintaining ice-free areas via discharge of warmer water relative to surface flow. Groundwater
influence was well documented during the 1980s studies, particularly in side channel, side
slough, and upland slough habitats utilized by adult salmon for spawning and juvenile fish
species for winter rearing (Trihey & Associates and Entrix 1985). Water temperatures of
groundwater were observed to remain between 2.5° – 4.0°C through the winter period, whereas
Susitna River main channel temperatures were typically measured to be near 0°C (Keklak and
Quane 1985). The source of upwelling in Middle Susitna River habitats was attributed to three
primary types of subsurface flow: 1) lateral hyporheic flow of surface streamflow from the
Susitna River main channel, 2) subsurface flow from upland sources, and 3) hyporheic flow
within the Susitna floodplain alluvium (Trihey & Associates and Entrix 1985). The primary
groundwater source in Middle Susitna River side channel and side slough habitats was
determined to be derived from lateral hyporheic flow from the Susitna River main channel. The
1980s studies further documented that changes in main channel stage could result in relatively
rapid changes (several hours) in the amount of side slough flow (i.e., groundwater discharge)
(Trihey 1982, Trihey & Associates and Entrix 1985). Increases in Susitna River stage can also
affect groundwater-fed habitats via overtopping, or breaching of the inlets to side channels and
side sloughs resulting in a mixing of both surface and groundwater. Breaching events
documented by the 1980s studies during winter staging demonstrated that such events affected
the amount of the flow and associated water quality characteristics, in particular, water
temperature and dissolved oxygen. Breaching flows typically resulted in increased flows and
water velocities within the channel that would result in concomitant reductions in both surface
and intragravel water temperatures (Labelle 1984, Trihey & Associates and Entrix 1985).
Groundwater upwelling was considered to be the principal factor affecting salmon egg
development and survival in the Middle Susitna River; groundwater helps to maintain stable
water levels, provides warmer water relative to surface streamflow and promotes intergravel
water exchange that is critical for maintenance of adequate water quality conditions for embryo
development (Vining et al. 1985). Salmon embryos in habitats with unstable or insufficient
groundwater discharge were more susceptible to mortality due to dewatering and freezing than in
areas with stable groundwater flow (Vining et al. 1985). Intergravel water temperature is also a
critical factor during salmon egg incubation, affecting the rate of embryo and alevin development
and determining the solubility of oxygen in water (Bjornn and Reiser 1991, Quinn 2005). In
general, embryos develop faster at warmer water temperatures, but this relationship varies with
species. At 5°C, incubation time (fertilization to hatching) was observed to range dramatically
among coho (Oncorhynchus kisutch) (139 days), chum (O. keta) (161 days), sockeye (O. nerka)
and pink (O. gorbuscha) (173 days, each species) and Chinook (O. tshawytscha) (191 days)
salmon (Murray and McPhail 1988, Quinn 2005). At 2°C, incubation time increased more than
60% for coho, sockeye and Chinook salmon (Murray and McPhail 1988, Quinn 2005). Although
incubation may occur at near freezing temperatures, increased mortality can occur at low
temperatures during the early stages of incubation (Burgner 1991, Salo 1991, Bjornn and Reiser
1991).
Groundwater discharge often contains low levels of dissolved oxygen as organic matter is
processed by microbes within the subsurface environment (Allan and Castillo 2007). Uptake of
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FERC Project No. 14241 Page 4 September 2014
dissolved oxygen by salmon embryos may depend on various factors in addition to dissolved
oxygen concentration, including gravel permeability and hyporheic flow or exchange rates, such
that reduced substrate porosity and flow can inhibit embryo development (Quinn 2005).
Research with chum salmon embryos indicated that the amount of oxygen needed by the embryo
increases with development time and that embryo sensitivity to hypoxia was greatest early in the
incubation period (Alderdice et al. 1958, Bjornn and Reiser 1991, Salo 1991). Although acute
mortality in salmon embryos occurs at low dissolved oxygen concentrations (2.0 – 2.5 mg/L),
delayed or deformed development of the embryo and premature hatching can occur at levels
above this critical minimum (Alderdice et al. 1958, Bjornn and Reiser 1991, Quinn 2005).
1.2.3. Salmonid Egg Incubation and Survival During the Winter
Conditions for salmon egg incubation varied considerably among macrohabitats during winter
studies conducted during the 1980s. During those studies, hydrologic connectivity to the Susitna
River main channel and presence of groundwater upwelling were considered to be primary
factors that affected salmon egg incubation timing and success (Vining et al. 1985). Salmon
embryos located in macrohabitats that were most directly affected by Susitna River main channel
stage fluctuations and that lacked groundwater upwelling developed more slowly and were more
susceptible to high embryo mortality than areas with groundwater influence (Vining et al. 1985).
Embryo mortality was often due to dewatering and freezing as Susitna River stage declined
during early winter (Vining et al. 1985). Main channel, side channel, and tributary mouth
habitats were found to be most affected by Susitna River stage change, while side slough habitats
were more influenced by groundwater flow (Hoffman et al. 1983, Vining et al. 1985). Although
groundwater upwelling was present in the main channel, side channel, and tributary habitats, the
resulting flows were overwhelmed by the larger, colder main channel surface flows (Vining et al.
1985). Intergravel water temperatures in main channel and tributary habitats typically were
strongly affected by surface water and were near freezing during the winter, while the
groundwater influenced temperatures in side sloughs were warmer and more stable (Hoffman et
al. 1983; Seagren and Wilkey 1985; Vining et al. 1985). Intergravel temperatures in side channel
habitats were often variable and more dependent on site-specific conditions (e.g., groundwater
input and inlet breach elevation) that controlled the relative influence of groundwater and surface
water sources (Vining et al. 1985). Intergravel dissolved oxygen concentrations in main channel,
side channel, and tributary habitats were generally high (>8 mg/L) and reflected surface water
concentrations (Hoffman et al. 1983, Vining et al. 1985). In contrast, intergravel dissolved
oxygen concentrations in side sloughs were often low (<4 mg/L) and differed from measured
surface water concentrations (Hoffman et al. 1983, Vining et al. 1985).
Salmon embryos in Middle Susitna River habitats were observed to hatch between January and
April, though timing can vary between species and location (Hoffman et a. 1983, Wangaard and
Burger 1983). After hatching, salmon alevins may remain in the gravel for one to three months,
depending on intergravel conditions (Hoffman et a. 1983, Wangaard and Burger 1983). Initially
after hatching, alevins are relatively immobile, but their ability to react to adverse conditions
increases with the development of fins and absorption of the yolk sac. Fast and Stober (1984)
found that Chinook, coho, chum and steelhead alevins all moved vertically downward up to 20
cm within artificial redds, which was the maximum possible in the experimental design, in
response to favorable velocity, dissolved oxygen, and light conditions (Fast and Stober 1984).
Similarly, upstream and downstream (horizontal) intergravel movement has been documented in
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FERC Project No. 14241 Page 5 September 2014
separate laboratory experiments (Dill 1969, Fast and Stober 1983). In response to variable
intergravel velocities (0.02 feet per second [fps] and 0.066 fps), pre-emergent salmonid alevins
exhibited positive rheotaxis, while movement direction was random at zero velocity (Fast and
Stober 1984). Intergravel movement by salmon alevins appears to be selective in terms of
habitat conditions. Within tanks that were bifurcated to provide two choices of different
dissolved oxygen concentrations (2 vs. 6 mg/L, 4 vs. 6 mg/L, and 6 vs. 10 mg/L), alevins of each
species (Chinook, coho, chum, and steelhead) moved within the intergravel environment toward
the water source of higher oxygen concentration (Fast and Stober 1984). Selective intergravel
movement by alevins may be particularly critical during fluctuating streamflows and periods of
redd dewatering.
The effects of complete redd dewatering has been previously investigated, with results indicating
that dewatering tolerance varies by developmental stage. Both Reiser and White (1983) and
Becker et al. (1982) found that salmonid eggs could withstand several weeks (1 to 5 weeks) of
dewatering provided they were maintained within a moist environment and temperatures
remained above freezing. In contrast, salmonid alevins and pre-emergent fry were vulnerable to
even short periods of dewatering (1 to 4 hours) (Becker et al. 1982; Reiser and White 1981).
However, Fast and Stober (1983) observed that salmon alevins survived variable periods of
dewatering (up to 48 hours), but that alevin survival declined with duration of dewatering, and
the length of time that alevins tolerated dewatering declined with age from date of hatching;
individuals older than 30 days post-hatch experienced low survival (range: 0 – 18%) in response
to two hours of dewatering (Fast and Stober 1983). The degree of mortality due to the
dewatering of eggs in redds within the Susitna River during the winter period would likely vary
widely depending on the extent of groundwater influence at the different redd locations. In areas
where groundwater is prevalent, as may be the case in side sloughs and upland sloughs,
temperatures may remain above freezing in the redd (due to warming of the intergravel
environment from the warmer groundwater below the redd) during short-term periods of
dewatering. In areas of no or little groundwater influence, any dewatering during the winter
periods would likely result in 100 percent mortality of the eggs due to freezing.
Salmon alevins are generally light averse in the intergravel environment, though tolerance to
light increases near the end of the alevin phase (Quinn 2005). Despite this increased light
tolerance, most salmon fry emerge from the gravel at night (Heard 1964, Godin 1980, Quinn
2005). Following emergence, salmon fry fill their swim bladder to obtain neutral buoyancy, at
which point the phase of intergravel residence is over and they become free-swimming. Habitat
use by salmon fry immediately after emergence is not well known, though many fry are believed
to retain close association with substrates near the redd site (Quinn 2005). During this period,
salmon fry are sensitive to environmental conditions, including fluctuations in river stage. Fry
stranding can occur during periods of declining river stage as fish become stranded on the
substrate above the surface water stage. Previous studies of salmon stranding occurrence relative
to river streamflow fluctuations determined that stranding was size selective among salmon fry
and that individuals less than approximately 50 mm in length were particularly susceptible
(Bauersfeld 1977, Bauersfeld 1978, R.W. Beck and Associates 1989, Olson 1990). A more
detailed review of the effects of flow fluctuations on both fish and aquatic invertebrates, which
are often termed pulse type flows, is found in Reiser et al. (2005).
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1.2.4. Winter Habitat Conditions for Juvenile and Adult Fish
Winter habitat conditions in Alaskan Rivers can be severe for juvenile and adult fish species.
Extreme low water temperature is a primary factor affecting overwintering fish, as reduced
temperature can affect fish metabolism, feeding, diel behavior, swimming ability, and predator
avoidance (Beamish 1978, Brown et al. 2011). Ice formation on the channel margins, substrate,
and water surface can also affect fish habitat in terms of channel constriction and reduced habitat
area, decreased light penetration into the water, and alteration of water quality conditions (e.g.,
dissolved oxygen concentration) (Prowse 2001). Suspended frazil ice can cause direct injury or
mortality to fish by plugging or abrading gills, while anchor ice and ice dams can eliminate or
modify aquatic habitat to the extent that it becomes unsuitable for fish (Brown et al. 1993, Brown
et al. 2011).
Nearly all juvenile and adult fish species exhibit physiological and/or behavioral adjustments in
response to seasonal changes in habitat conditions from summer to winter. During fall, many
fish will move to winter habitats. Suitable winter habitats allow fish to minimize energy
expenditure while providing a stable environment that is protected from environmental extremes
(Brown et al. 2011). Winter habitat can be characterized by the presence of groundwater
upwelling, structural complexity (e.g., large wood), coarse substrate, low current velocity, deep
pools, and off-channel areas protected from more extreme main channel hydrologic conditions
(Muhlfeld et al. 2001, Mitro and Zale 2002, Harper and Farag 2004, Brown et al. 2011).
Juvenile salmonids in various winter settings have been observed to conceal themselves within
the interstitial spaces in coarse substrate (Meyer and Gregory 2000, Muhlfeld et al. 2001, Brown
et al. 2011). Adult fish too large to utilize interstitial habitats often seek deep pools in main
channels (Reynolds 1997). In the Susitna River during the 1980s studies, juvenile coho salmon
used groundwater-fed side sloughs and upland sloughs for winter habitat, in addition to natal
tributaries, while primary winter habitats for juvenile Chinook consisted of side slough and side
channel areas with groundwater upwelling (Delaney et al. 1981, Stratton 1986). Adult rainbow
trout (Oncorhynchus mykiss) and Arctic grayling (Thymallus arcticus) in the Susitna River
migrated from spawning and feeding tributaries in late summer to main channel areas that were
typically downstream and proximal to the spawning tributary, though some individuals exhibited
long distance (> 20 miles) movements (Hoffman et al. 1983, Sundet and Pechek 1985, Sundet
1986). The specific habitat features of Susitna River holding areas used by adult resident species
during 1980s winter telemetry studies were difficult to measure, though groundwater upwelling,
overhead cover (depth and/or ice cover), lack of frazil and/or anchor ice, and low water velocity
appeared to be common characteristics of known holding habitats (Schmidt et al. 1983, Sundet
and Pechek 1985).
Fish commonly aggregate during winter, perhaps due in part to the reduced amount of habitat
area in winter relative to summer (Cunjak and Power 1986). Although competitive interactions
between individuals may otherwise limit large aggregations, reduced territorial aggression during
winter is likely one mechanism by which aggregations occur (Reynolds 1997). In the Susitna
River, radio telemetry during 1980s studies indicated that adult rainbow trout and Arctic grayling
utilized the same main channel areas for winter habitat, while similar tracking data suggested
aggregation of Arctic grayling and burbot (Lota lota) in the Middle Susitna River main channel
habitats (Sundet and Wenger 1984, Sundet 1986). Arctic grayling distribution has similarly
observed to be patchy in other Alaska rivers (West et al. 1992, Reynolds 1997). The same winter
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FERC Project No. 14241 Page 7 September 2014
habitats are often used from year to year by fish species, which may indicate that stable
environments are critical during the winter period (Reynolds 1997).
Diel behavior and activity patterns of fish species often change during winter in response to cold
water temperature, ice formation, and low light conditions (Reeves et al. 2009, Valdimarsson and
Metcalfe 2001). At low water temperatures particularly, salmon activity will often shift from
diurnal in summer and fall to nocturnal during winter to minimize energy expenditure and reduce
predation risk (Roni and Fayram 2000, Quinn 2005). Ice cover and light intensity may be
mitigating factors based on studies examining the effect of ice cover on salmonid behavior
during winter. Brown trout (Salmo trutta) that were primarily nocturnal during winter exhibited
greater activity and foraging behavior in the presence of ice cover relative to its absence (Watz et
al. 2013). Similarly, juvenile Atlantic salmon (Salmo salar) that were primarily nocturnal during
winter exhibited greater activity levels during daytime in areas of ice cover relative to open-
water (Linnansaari et al. 2008).
1.2.5. Summary
As noted above, winter instream flow conditions are an important component of fish habitat in
the Susitna River, particularly with respect to egg incubation and juvenile and adult holding.
Intergravel flow and groundwater upwelling are critical for egg incubation and emergent fry
survival, while surface water characteristics (e.g., temperature, depth, and velocity) can be
important aspects of winter habitat for juvenile and adult fish. Although groundwater has been
observed to be an important aspect of aquatic habitat for many fish species and life stages in the
Susitna River, the relationships between Susitna River streamflow, groundwater, and various
other habitat criteria and indices relevant to winter conditions are not completely understood.
The winter studies will result in an improved understanding of habitat conditions and utilization
by fish species and life stages needed to evaluate overall effects of altered Susitna River
streamflow on the quality and quantity of aquatic habitats. In terms of the IFS program,
observations of winter conditions and fish habitat utilization will support development of Habitat
Suitability Curve and Habitat Suitability Indices (HSC/HSI) for different fish species and life
stages that will be used to develop fish habitat-flow relationships needed for assessing winter-
time Project operational effects.
2. STUDY OBJECTIVES
The overall objectives of the 2013-2014 IFS winter studies were to evaluate potential
relationships between mainstem Susitna River stage and the quality and quantity of winter
aquatic habitats that support embryonic, juvenile, and adult life stages of fish species and to
record fish behavior and habitat utilization in support of HSC/HSI development. Specific tasks
of the study were as follows:
Compare water level (stage) responses in representative habitat types relative to
Susitna River main channel stage through the period of salmon egg incubation.
Monitor surface and intergravel water temperatures in representative habitat types, at
salmon spawning sites and in areas with and without groundwater influence, through
the period of salmon egg incubation.
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 8 September 2014
Evaluate potential relationships between Susitna River stage and water temperature
recorded in off-channel and main channel habitats.
Monitor intergravel dissolved oxygen at two salmon spawning sites in off-channel
habitats with groundwater influence.
Describe juvenile and adult fish behavior in representative habitats during day and
night conditions to discern potential patterns in behavior and habitat use.
Record site-specific habitat utilization data for juvenile and adult fish species in
support of HSC/HSI development.
3. STUDY AREA
The 2013-2014 IFS winter studies were conducted in the Middle River Segment of the Susitna
River between the Three Rivers Confluence (PRM 102.4) and PRM 143. Data collection
primarily occurred within three Focus Areas (FAs): FA-104 (Whisker Slough), FA-128 (Slough
8A), and FA-138 (Gold Creek); however, opportunistic sampling also occurred within FA-141
(Indian River) (Figure 1). These FAs were selected for the 2013-2014 study because they
contain a diversity of habitat types with groundwater influence, they have documented fish
utilization by multiple fish species and life stages, and they could be safely accessed during the
winter. Candidate sampling locations within the study area were identified prior to sampling
such that the relative data collection effort was similar among FA-104 (Whisker Slough), FA-
128 (Slough 8A), and FA-138 (Gold Creek). However, adjustments to proposed sampling
locations were made during each field effort based upon known fish distributions (e.g.,
spawning), logistical considerations (e.g., site access, ice cover), and site hazards and personal
safety. Work was primarily based out of Talkeetna and Gold Creek camp, although temporary
field camps were also used at FA-104 (Whiskers Slough), FA-128 (Slough 8A), and FA-138
(Gold Creek).
4. METHODS
The 2013-2014 IFS winter studies were comprised of two primary components: 1) monitoring of
water level, water quality, and ice conditions and 2) fish behavior and habitat use observations.
Data collection occurred during three trips in early 2014: February 3-16, March 4-16, and April
1-12. The 2013-2014 winter studies were coordinated with the study leads for IFS (Study 8.5),
FDA (Study 9.6), Groundwater (Study 7.5), Geomorphology (Study 6.5), Water Quality (Study
5.5), and Ice Processes (Study 7.6). Methods utilized during the 2013-2014 study were initially
developed during the 2012–2013 pilot winter study conducted at FA-104 (Whiskers Slough) and
FA-128 (Slough 8A) (AEA 2014, Study 8.5 Appendix L).
4.1. Water Surface Elevations
Water level and selected water quality parameters (water temperature and dissolved oxygen)
were continuously monitored during winter 2013-2014 at nine sites in FA-104 (Whiskers
Slough), eight sites in FA-128 (Slough 8A), and seven sites in FA-138 (Gold Creek) (Figure 2,
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FERC Project No. 14241 Page 9 September 2014
Figure 3, and Figure 4). Continuous monitoring sites were established during the conclusion of
the salmon spawning period in the Middle River Segment in September and early October 2013.
Water level and water quality instruments were installed at representative macrohabitat types in
each FA, which consisted of main channel, side channel, side slough, upland slough, and
tributary habitats. Macrohabitat designations (e.g., side channel, side slough) used for the 2013-
2014 winter studies were based on 2012 Middle River Segment remote line habitat mapping
(HDR 2013). Continuous monitoring sites were comprised of areas with known or suspected
groundwater upwelling, bank seepage and lateral intergravel flow from the main channel, mixing
between upwelling and bank seepage, little apparent intergravel discharge, and areas where fish
had been observed spawning. Salmon spawning was observed during fall 2013 near three sites
in each of FA-104 (Whiskers Slough) (104-WESC-10, 104-WSL-20, and 104-WC-10) and FA-
138 (138-SL11-04, 138-SL13-05, and 138-USC11-09) (Figure 2, Figure 4). In FA-128, five
sites (128-SLA-20, 128-SC-05, 128-SC8A-25, 128-SL8A-15, and 128-SL8A-40) coincided with
observed 2013 salmon spawning areas (Figure 3).
Water level at continuous monitoring sites was recorded using pressure transducers (Solinst
Levelogger Model 3001) deployed at the substrate surface. Transducers were anchored with
weights and attached to metal stakes driven into the substrate to prevent shifting during the
deployment period. Pressure data recorded at each site were compensated with air barometric
pressure data (Solinst Barologger Model 2001) recorded at each Focus Area (Figure 2, Figure 3
and Figure 4). Data collected during periods of low Susitna River streamflow in which pressure
transducers appeared to become dewatered were eliminated from the affected stage records. To
facilitate visual comparisons of stage between macrohabitat types, water level data were
normalized to zero at the earliest common start time for transducers within each Focus Area.
Stage records at each monitoring site in FA-104 (Whiskers Creek) was equalized to zero on
October 1, 2013, while stage records at each site in FA-128 (Slough 8A) and FA-138 (Gold
Creek) were set to zero on September 30, 2013. Aerial reconnaissance photo surveys of FA-104
(Whiskers Slough) performed by groundwater personnel during November 2013 were used to
validate stage conditions among macrohabitats, including side channel and side slough inlet
breach conditions that were apparent from continuous water level data.
Water level instruments accessible during winter were downloaded during March or April 2014.
At salmon spawning locations, instruments were redeployed in March 2014 to collect additional
data during the remaining salmon egg incubation period and spring ice breakup. Instruments at
FA-104 (Whiskers Slough) salmon spawning sites were retrieved in June 2014, while most
instruments at FA-128 (Slough 8A) and FA-138 (Gold Creek) will be retrieved during
September 2014 (Table 1). At accessible non-spawning sites, instruments were removed prior to
ice breakup to limit data loss and damage to equipment.
4.2. Water Quality
Surface and intergravel water temperatures and intergravel dissolved oxygen concentrations were
continuously recorded during 2013-2014 IFS winter studies (Figure 2, Figure 3 and Figure 4). In
each Focus Area, water temperature loggers (Hobo Tidbit v2) were deployed in surface water at
the substrate and 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). Surface and
intergravel temperature loggers were attached to a stainless steel cable and inserted into the
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FERC Project No. 14241 Page 10 September 2014
gravel at the appropriate depth using a steel installation device (sensu Zimmerman and Finn
2012). Water temperature loggers at salmon spawning sites that were accessible were
downloaded during late winter 2014 and redeployed to record conditions through spring ice
breakup and the period of salmon egg incubation (Table 1).
Intergravel dissolved oxygen concentrations were recorded with HOBO U26-001 loggers in two
locations, one each within FA-128 (Slough 8A) and FA-138 (Gold Creek). The locations
represented sites adjacent to observed 2013 salmon spawning areas (sites 128-SL8A-40 and 138-
SL11-04) (Figure 3 and Figure 4). The loggers, which also recorded intergravel water
temperature, were deployed approximately 20 cm below the substrate surface within a perforated
PVC housing. Data from the loggers were downloaded during the field visits provided they were
accessible; instantaneous measurements of dissolved oxygen and temperature were taken using a
hand-held water quality meter (Hach HQ40D) at the same depths as the loggers (i.e., 20 cm
below the substrate surface) for comparative purposes. Dissolved oxygen loggers were removed
prior to spring breakup 2014 to avoid potential equipment loss (Table 1).
The relationship between main channel stage and surface and intergravel water temperature was
evaluated in conjunction with water level for all monitoring sites. For each comparison, stage
records were normalized to zero at the start of data collection to facilitate visual comparison.
Stage records at each monitoring site in FA-104 (Whiskers Creek) was equalized to zero on
October 1, 2013, while stage records at each site in FA-128 (Slough 8A) and FA-138 (Gold
Creek) were set to zero on September 30, 2013.
Instantaneous measurements (spot measurements) of surface and groundwater quality were
recorded during February, March, and April 2014 in each Focus Area at IFS monitoring sites,
groundwater wells and sites associated with fish capture and observation (Figure 2, Figure 3, and
Figure 4). Spot water quality data were recorded at two groundwater wells in each Focus Area
(six wells total) (Figure 2, Figure 3 and Figure 4). These consisted of water temperature, specific
conductance, and dissolved oxygen concentration recorded using a hand-held water quality meter
(Hach HQ40D). Surface water quality at IFS sites was recorded at mid-column water depth.
Measurements of groundwater quality were taken within each of the groundwater wells and at
the two dissolved oxygen monitoring sites approximately 20 cm below the substrate surface.
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).
Ice thickness and water depth were measured in association with water quality measurements at
continuous and instantaneous monitoring sites. Hand and power augers were used to drill holes
(2 – 10 inch) in the ice to access surface water and measure ice thickness. Ice and water depth
measurements recorded were ice thickness, total water depth, and effective water depth, which is
the depth from the bottom of ice cover to the substrate.
A total of 13 water samples (7 surface water and 6 groundwater) were collected for laboratory
chemical analyses including nutrients (NO3, NO2, NH4, TKN, TP), total and dissolved metals,
methyl mercury, chlorophyll-a, total and dissolved mercury, and total and dissolved organic
carbon. Samples were collected in the field by R2 Resource Consultants following methods
outlined by URS and transported to URS staff in Talkeetna or Anchorage for next day shipment
to analytical laboratories. Field parameters of water quality were also measured in each Focus
Area along longitudinal transects (100m) in sloughs or side channels adjacent to the groundwater
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FERC Project No. 14241 Page 11 September 2014
wells. Temperature, specific conductance, and dissolved oxygen (DO) were measured at 10 m
increments in open leads where available or through holes augered in the ice.
4.3. Fish Observations
Fish capture and observation efforts occurred in each Focus Area during February, March, and
April 2014. Electrofishing methods were used in ice-free areas to capture fish and collect site-
specific HSC/HSI data. Surveys were conducted using a backpack electrofisher (Smith Root
LR-24) at 23 open-water sites in FA-104 (Whiskers Slough), FA-128 (Slough 8A), and FA-138
(Gold Creek). One site in FA-141 (Indian River) was opportunistically sampled during the April
2014 sampling effort. Paired day and night surveys were conducted at a subset of electrofishing
sites (n = 11) to help evaluate potential differences in fish diel activity patterns. HSC/HSI data
(e.g., water depth, water velocity, substrate size, and composition) were measured at the point of
fish capture during electrofishing sampling. Water depth and velocity measurements were made
using a wading rod and Price AA water velocity meter. Water temperature, dissolved oxygen,
and specific conductance were recorded at the locations of fish observations using a hand-held
water quality meter (Hach HQ40D).
Underwater fish observations in ice-covered areas within side slough and tributary habitats were
recorded using underwater video during day and night periods. A total of five sites were
surveyed by IFS staff in FA-104 (Whiskers Slough), FA-128 (Slough 8A), and FA-138 (Gold
Creek). Observations were documented using an underwater video camera (Aqua-Vu MC2x)
with a peripheral infrared light source (SeaViewer Model 42), each of which was equipped with
a pole extension. White light sources were used as little as possible during night surveys to
minimize the effect of visible light on fish behavior. At each site, multiple holes were drilled in
the ice using an ice auger to accommodate the video and infrared light equipment. At each ice
hole, an underwater survey was conducted for approximately four minutes by slowly rotating the
camera 360° for two rotations with 30 second pauses at each 90° position (Carlson and Quinn
2005). Ice hole stations were surveyed sequentially in an upstream direction to minimize fish
disturbance. Observed fish were enumerated by species and size class and HSC/HSI data were
recorded, provided the target fish was observed maintaining a stationary position. As for the
electrofishing surveys, the video surveys were performed during day and night to help evaluate
potential behavioral differences in fish diel activity in the Susitna River during winter.
Underwater video was also used by FDA staff, in conjunction with Adaptive Resolution Imaging
Sonar (ARIS) technology, during the 2013-2014 winter effort to monitor fish presence,
movement and behavior (AEA 2014b).
4.4. Deviations from Study Plan
The 2013-2014 IFS winter studies methods were implemented as described in the Study Plan
with no variances (see ISR Study 8.5, Section 4.5.1.10).
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 12 September 2014
5. RESULTS
5.1. Water Surface Elevation
5.1.1. FA-104 (Whiskers Slough)
Water levels at various locations within FA-104 (Whiskers Slough) varied widely over the
period of the winter studies in response to ice formation and staging. At main channel Site 104-
MC-40 water levels declined during October and early November 2013 prior to solid river ice
formation, and then increased markedly during main channel staging in late November 2014
(Figure 5). Short-term stage oscillations ranging from 0.5 – 4.0 feet were recorded during
December 2013 through March 2014 and a large stage increase occurred in early May 2014 in
association with spring ice breakup (USGS 2014) (Figure 5). Water levels at side channel sites
104-WSC-10 and 104-WESC-10 closely resembled the main channel stage record at Site 104-
MC-40; stage recorders at each site appeared to be dewatered for short periods in November
2014 (Figure 5). At side channel sites 104-WSC-30 and 104-SL3B-10 stage recorders did not
register short-term fluctuations during low stage periods in October 2013 and during January to
March 2014 (Figure 5).
The inlets to each side channel site 104-WSC-30 and 104-SL3B-10 were not breached by Susitna
River main channel streamflow following instrument installation in October 2013, though it was
apparent from aerial surveys that each channel inlet was breached during the late November
2013 staging event in FA-104 (Whiskers Slough). It was not possible to determine whether the
Whiskers Side Channel and Slough 3B inlets were breached during winter studies sampling in
February, March, and April 2014. Stage records at side slough (Site 104-WSL-20), upland
slough (Site 104-SL3A-70), and tributary (Site 104-WC-10) sites reflected large-scale stage
changes (> 5 feet) that occurred at Site 104-MC-40 during fall ice formation and spring ice
breakup. However, those sites were largely insensitive to small-scale stage changes (<1 foot)
that were apparent in the Susitna River main channel during January to April 2014 (Figure 5).
Aerial reconnaissance indicated that the Whiskers Slough inlet was breached and the Whiskers
Creek site was backwatered by main channel streamflow during staging in November 2013.
5.1.2. FA-128 (Slough 8A)
In FA-128 (Slough 8A), Susitna River main channel water levels at Site 128-MC-10 declined
during late September and October 2013 and likely became dewatered prior to main channel
staging in early December (Figure 6). Following Susitna River main channel staging, the water
level at Site 128-MC-10 continued to increase and peaked in early January 2014 and
subsequently declined until the stage recorder was removed in April 2014 (Figure 6). The inlet
to Side Channel 8A was not breached by Susitna River main channel flow during instrument
installation in late September 2013; recorded stage at Site 128-SC8A-25 was stable relative to
the main channel site (128-MC-10) during October to December 2013 (Figure 6). However,
Susitna River main channel flow appeared to breach the Side Channel 8A inlet during a main
channel freeze-up event in mid-January 2014, which caused a substantial rise in water level (4 –
8 feet) at Site 128-SC8A-25 (Figure 6). The subsequent stage record at 128-SC8A-25 during
February to April 2014 resembles the recorded stage at main channel Site 128-MC-10 (Figure 6).
Water level records at Side Slough 8A Site 128-SL8A-40 were generally steady through the
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 13 September 2014
period of record with the exception of a short-term increase in stage of approximately three feet
that occurred in late February 2014 when Susitna River main channel flow breached the Slough
8A inlet (Figure 6). This breaching event was less evident at the lower Slough 8A Site
(ESSFA128-1) because water levels at this site were affected by backwater from Side Channel
8A flow. Water levels in Slough A (128-SLA-20) were steady through the period of record and
did not reflect stage fluctuations associated with the Side Channel 8A and Slough 8A breach
events (Figure 6). Stage records in upland slough sites (128-US1-10, 128-US2-15) appeared
independent of the main channel stage at Site 128-MC-10 until mid-January, at which point high
flow volumes in Side Channel 8A affected water levels in each channel (Figure 6).
5.1.3. FA-138 (Gold Creek)
Water levels at FA-138 (Gold Creek) main channel Site 138-MC-50 decreased during late
September and October 2013 and the channel was likely dewatered during the period of Susitna
River main channel ice formation (late October to early December 2013) (Figure 6). Following
the peak main channel stage in mid-December 2013 at Site 138-MC-50, water levels fluctuated
between 0.5 to 3.0 feet between January to March 2013 (Figure 7). The stage in the Upper Side
Channel 11 Site, Site 138-USC11-09, closely resembled that of main channel Site 138-MC-50
for most of the data period (Figure 7). Recorded water levels in Slough 11 were stable relative to
the main channel and side channel sites, with the exception of the period of ice formation in mid-
December (Figure 7).
5.2. Water Quality
5.2.1. FA-104 (Whiskers Slough)
Surface and intergravel water temperatures differed among habitat types at FA-104 (Whiskers
Slough) during the 2013-2014 winter study based on data collected at nine continuous
monitoring sites. In the Susitna River main channel (Site 104-MC-40), surface and intergravel
temperatures were near 8°C during the September 2013 deployment and were very near 0°C
during the period of ice cover in the main channel (December 2013 – April 2014) (Figure 8). In
the lower portion of Whiskers Side Channel (Site 104-WSC-10), temperatures generally
resembled that of the main channel site as surface and intergravel temperatures were both
typically below 2°C during December 2013 through early March 2014 (Figure 8). At Site 104-
WSC-30 in the upper extent of Whiskers Side Channel, surface and intergravel water
temperatures were stable at approximately 4°C prior to the period of ice formation. Starting in
late November 2013, water levels increased substantially in the main channel (Site 104-MC-40)
and Whiskers Side Channel during which time temperatures at each gradient at Site 104-WSC-
30 decreased to near 0°C (Figure 9). Following ice formation and apparent main channel water
level decrease, intergravel temperature at Site 104-WSC-30 increased to between 2 – 4°C (Figure
9). At side channel sites 104-WESC-10 and 104-SL3B-10, water temperatures were generally
cooler than the main channel site prior to ice formation and warmer following freeze-up. Water
temperatures at these sites declined to near 0°C during the main channel stage increase in late
November 2013 (Figure 9 and Figure 10). Surface and intergravel temperatures dropped below
zero during a presumed period of dewatering in mid-November when water levels in the Susitna
River main channel and Whiskers East Side Channel were low (Figure 10). Although the inlets
to Whiskers Side Channel, Whiskers East Side Channel, and Slough 3B were breached by
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 14 September 2014
Susitna River main channel flow during the November 2013 reconnaissance flight, it was not
evident based on visual observations whether the inlets were breached during data collection
periods in February, March, and April 2014.
At upland slough Site 104-SL3A-70, surface and intergravel temperatures were warm (>2°C)
relative to the Susitna River main channel site (104-MC-40) and generally stable through the
data collection period, with negligible temperature reduction during the ice formation period in
late November 2014 (Figure 10). Whiskers Slough (Site 104-WSL-20) temperatures were cooler
than the main channel site prior to freeze-up and warmer during December 2013 to February
2014 (Figure 10). Surface and intergravel water temperatures declined to near 0°C during the
November 2013 freeze-up and May 2014 ice break-out periods, that coincided with high main
channel stage (Figure 11). The Whiskers Slough inlet was breached by Susitna River main
channel flow during the November 2013 reconnaissance flight but did not appear breached
during February and March 2014 data collection efforts. Intergravel temperatures at the
Whiskers Creek site (104-WC-10) tracked surface temperatures during the period of record and
generally remained below 2°C throughout the period of ice cover (December 2013 – April 2014)
(Figure 11).
Spot measurements of surface water temperature recorded in February and March 2014 at FA-
104 (Whiskers Slough) indicated generally warmer surface water in side slough and upland
slough habitats relative to the Susitna River main channel, which was consistent with data
recorded at the continuous temperature monitoring sites (Figure 12). Specific conductance
values at mainstem spot measurement sites were conversely higher than off-channel and tributary
areas (Figure 12). Measurements within the groundwater wells found temperatures were warmer
and conductance values intermediate to other sites (Figure 12). Exceptions to this general trend
were at side channel Site 104-SL3B-10, which exhibited specific conductance and water
temperatures unlike other side channel sites, and side slough Site 104-CFSL-10 where specific
conductance was more similar to mainstem habitats than other side slough habitats (Figure 12).
Groundwater upwelling measured at Site SL3A-11 exhibited similar temperature and
conductivity values to those of surface water measurements at Site 104-SL3A-10, but
substantially lower dissolved oxygen concentrations (Table 2). Specific conductance ranged
from 125.3 – 265 µS/cm among main channel (Site 104-MC-50), Whiskers Side Channel
(WSC), and Whiskers East Side Channel sites, 200.5 µS/cm at side slough Site CFSL-10, 90.9
µS/cm at side channel Site SL3B-10, 32.9 – 75.5 µS/cm at Whiskers Slough (WSL) sites, 32.3 –
35.7 µS/cm at Whiskers Creek (WC) sites, 92.0 µS/cm at Site 104-SL3A-70, and 124.0 µS/cm at
groundwater well Site ESGFA104-10-W1 (Table 2 and Figure 12).
Ice cover in FA-104 (Whiskers Slough) was nearly complete in each macrohabitat during data
collection efforts in February, March, and April 2014. Monitoring sites with open-water leads
were 104-WSC-30, 104-SL3B-10, 104-CFSL-15, and 104-SL3A-10 (Table 2). During March
2014, ice thickness was 3.6 feet in the main channel, ranged from 0 – 2.2 feet among side
channel sites, and ranged from 0 – 1.1 feet among side slough sites (Table 2).
5.2.2. FA-128 (Slough 8A)
Surface temperatures at FA-128 (Slough 8A) Site 128-MC-10 ranged from 0-6°C prior to main
channel ice formation in September and October 2013, and then dropped below zero during a
presumed period of instrument dewatering in November and December 2014 (Figure 13).
During the period of ice cover, surface water temperatures at Site 128-MC-10 were near 0°C
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 15 September 2014
(Figure 13). At Side Channel 8A monitoring Site 128-SC8A-25, surface and intergravel
temperatures exhibited minimal vertical thermal gradient during September and October 2013
prior to Susitna River main channel ice formation, but varied during freeze-up in November
2013 (Figure 13). Surface and intergravel water temperature at Site 128-SC8A-25 declined to
near 0 °C in mid-January coincident with the influx of Susitna River main channel flow into Side
Channel 8A and abrupt increases in the Side Channel 8A stage (Figure 13). Water temperatures
in Slough 8A were generally warmer (4°C intergravel temperature) and more stable through the
data collection period than at monitoring sites in the main channel (128-MC-10) and Side
Channel 8A (128-SC8A-25). However, short-term reductions in surface and intergravel
temperature were evident in November 2013 and February 2014 (Figure 14). Similarly, surface
and intergravel temperatures at Upland Slough 2 were warm (3-4°C) and stable with the
exception of short-term declines in temperature coincident with transitory stage increases (Figure
15). At Upland Slough 1 and near the mouth of Skull Creek, surface and intergravel
temperatures declined substantially during late November 2013 and remained low (<1°C) during
December 2013 through March 2014 (Figure 15 and Figure 16). Surface and intergravel water
temperatures at the Slough A monitoring site (128-SLA-20) declined below 1°C during the
period of ice formation in November 2013 and increased to approximately 2°C in late December
2013 and January 2014 (Figure 16).
Intergravel dissolved oxygen measurements recorded at approximately 20 cm below the
substrate surface at Site 128-SL8A-40 were generally stable at approximately 5.5 mg/L during
September 2013 through March 2014, excepting periods during November 2013 (3 weeks) and
February 2014 (1 week) when concentrations were elevated (Figure 17). Intergravel water
temperatures at this site tended to be stable at nearly 4.5°C during most of the measurement
period, but exhibited abrupt declines during periods coincident with apparent dissolved oxygen
fluctuations (Figure 17). Dissolved oxygen and temperature fluctuations during February 2014
occurred during the Slough 8A inlet breach event observed during IFS data collection at FA-128
(Slough 8A).
Spot water quality measurements measured in FA-128 (Slough 8A) during February and March
2014 indicated that side slough and upland slough habitats were generally warmer relative to
main channel and side channel areas, but that specific conductance was not substantially
different among habitats (Figure 18). Instantaneous surface water temperature measurements
ranged from 0.1°C at main channel Site 128-MC-10, 0.1 – 1.1°C at Skull Side Channel (SSC)
sites, 0.2 – 0.5°C at Side Channel 8A (SC8A) sites, 0.3 – 1.2°C among Slough 8A (SL8A) sites,
0.2°C at Upland Slough 1 (US1), 1.6°C at Upland Slough 2 (US2), 2.4 – 4.1°C at Upland Slough
3 (US3) sites, 0.3 – 2.1°C at Half Moon Slough (HMSL) sites, 1.1°C at the Skull Creek mouth
(SC), and 1.2°C at Slough A (SLA) (Table 2). Specific conductance was lower in Slough 8A
(SL8A), upland slough (US1, US2 and US3), and tributary (SC) sites relative to main channel
and side channel habitats (Figure 18). Spot measurements of intergravel water (approximately
20 cm below substrate surface) measured at Site 128-SL8A-40 exhibited substantially higher
temperatures (4.5°C), lower conductivities (58.6 µS/cm) and lower dissolved oxygen (4.01
mg/L) than surface waters at that site (1.2°C, 214.8 µS/cm, and 11.75 mg/L) (Table 2). Specific
conductance measurements at FA-128 (Slough 8A) ranged from 284.1 µS/cm at main channel
Site 128-MC-50, 260.0 – 268.0 µS/cm at side channel sites (SC8A and SSC sites), 207.9 – 263.0
µS/cm among Slough 8A (SL8A) surface water sites, 165.1 µS/cm at Slough A (SLA), 125.9
µS/cm at Upland Slough 1 (US1), 191.3 – 193.6 µS/cm at Upland Slough 2 and 3 (US2 and
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 16 September 2014
US3) sites, 226.0 – 270.0 µS/cm at Half Moon Slough (HMSL) sites, and 162.9 µS/cm at the
Skull Creek mouth (SC) (Table 2).
Ice coverage was nearly complete in FA-128 (Slough 8A) with the primary exceptions of Side
Channel 8A and portions of Slough 8A and Skull Side Channel. Open leads at monitoring sites
in Slough 8A (e.g., 128-SL8A-40) and Skull Side Channel (128-SSC-15) were likely thermal
leads, while open-water in Side Channel 8A was the result of high water velocity. During
February and March 2014, ice thickness was 3.2 feet in the main channel, 2.0 feet at Site 128-
HMSC-01, 0.4 foot at Site 128-SL8A-15, ranged from 0 – 2.1 feet among upland slough sites,
and was 1.5 feet in Skull Creek (Table 2).
5.2.3. FA-138 (Gold Creek)
Susitna River main channel water temperatures at FA-138 (Gold Creek) monitoring site 138-
MC-50 declined from approximately 7°C in September 2013 to below zero in late October 2013
when surface water stage at the site was presumed to be zero (Figure 19). Following the dewater
period at main channel site 138-MC-50, which was estimated to occur from late October to
December 2013, surface and intergravel water temperature remained between 0-1°C (Figure 19).
In Upper Side Channel 11 (Site 138-USC11-09), surface and intergravel water temperatures
were warm (approximately 4°C) and stable during September and October 2013 relative to main
channel temperatures (Figure 19). Beginning in November 2013, a thermal gradient was evident
between surface and intergravel depths at Site 138-USC11-09, though all surface and intergravel
temperatures exhibited a short-term decline in December 2013 that was coincident with
transitory stage increases at main channel (Site 138-MC-50) and Upper Side Channel 11 (Site
138-USC11-09) sites (Figure 19). Surface water temperature records at the two monitoring sites
near the outlet of Slough 11 (sites 138-SL11-04 and 138-SL11-06) similarly declined from 4°C
in early October 2013 to between 1-2°C in November and remained generally stable at 2°C
during the ice covered period (December 2013 – March 2014), excepting a short-term decline to
near 0°C in mid-December (Figure 20). The surface temperature decline coincided with
increases in water level in the main channel (Site 138-MC-50) and at Site 138-SL11-04.
Intergravel water temperatures at Site 138-SL11-04 were stable at approximately 3.5°C through
the monitoring period, while intergravel temperatures at Site 138-SL11-06 generally resembled
surface water (Figure 20). At Slough 11 Site 138-SL11-20, surface and intergravel temperatures
declined from 8°C in September 2013 to near 0°C during a short-term stage increase in
December 2013 and fluctuated between approximately 1-2°C during January to March 2013
(Figure 21).
Intergravel dissolved oxygen at FA-138 (Gold Creek) Site 138-SL11-04 fluctuated generally
between 7 – 10 mg/L during September 2013 through April 2014, although some recorded
values were less than 4 mg/L (Figure 22). Intergravel temperatures at Site 138-SL11-04 were
generally stable ranging between 6 – 7°C during the measurement period (Figure 22).
Spot water quality measurements at FA-138 (Gold Creek) during February and March 2014
indicated that surface water in side slough and upland slough habitats was generally warmer
relative to main channel and side channel areas, but did not differ substantially in terms of
specific conductance (Figure 23). Exceptions to this general trend occurred at most groundwater
seepage measurement locations within side channel (138-USC11-12, 138-USC11-16, 138-
LSC11-11 and 138-LSC11-12) and side slough (138-SL11-04) sites (Figure 23, Table 2). Spot
surface water temperature measurements ranged from 0.2°C at main channel Site 138-MC-50,
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 17 September 2014
0.2 – 0.8°C at Upper Side Channel 11 (USC11), Lower Side Channel 11 (LSC11), and Side
Channel 14 (SC14) sites, 1.9°C at Side Channel 12 (138-SC12-05), 1.2 – 2.5°C among Slough
11 (SL11) sites, 0.1°C at Slough 12 (138-SL12-10), 1.6 – 2.2°C at Slough 13 (SL13) sites, and
0.3°C at Gold Creek (Table 2). Sites in Upper Side Channel 11 (USC11) and Lower Side
Channel 11 (LSC11), which included several visible groundwater sources, were most variable in
terms of temperature and specific conductance values among all macrohabitat types (Figure 23
and Table 2). Specific conductance of FA-138 (Gold Creek) surface water measurements ranged
from 245.0 – 269.0 µS/cm at main channel (MC) sites, 203.9 – 324.0 µS/cm at Upper Side
Channel 11 (USC11) sites, 261.0 – 275.0 µS/cm at Lower Side Channel 11 (USC11) sites, 261.0
– 264.0 µS/cm at Side Channel 12 and Side Channel 14 (SC12 and SC14) sites, 272.0 – 315.0
among Slough 11 (SL11) sites, 103.3 µS/cm at Slough 12 (Site 138-SL12-10), 202.6 – 256.0
µS/cm at Slough 13 (SL13) sites, 64.2 µS/cm at Slough 14 (Site 138-SL14-20), and 376.0 µS/cm
at the Gold Creek mouth (GC) (Table 2).
Ice coverage in FA-138 (Gold Creek) was most consistent in the main channel, although open
leads were present in each habitat type. During February and March 2014, ice thickness ranged
from 0 – 1.5 feet at the main channel monitoring site, 0 – 2.5 feet among side channel sites, 0 –
0.5 foot among side slough sites, and 0 – 0.5 foot among upland slough sites (Table 2).
5.3. Fish Observations
A total of 45 electrofishing surveys were conducted during IFS data collection efforts in FA-104
(Whiskers Slough), FA-128 (Slough 8A), FA-138 (Gold Creek), and FA-141 (Indian River), of
which 16 surveys were conducted at night (Table 3). Fish species captured during day and night
electrofishing surveys consisted of Chinook, sockeye, chum and coho salmon, rainbow trout,
Arctic grayling, Longnose sucker (Catostomus catostomus), and Arctic lamprey (Lethenteron
japonicum); sculpin (Cottid) were also captured, though these individuals were not identified to
species (Table 3). During the opportunistic survey of a main channel site in FA-141 (Indian
River), one Chinook and three coho salmon were captured (Table 3). A total of 248 fish were
captured during 28 daytime electrofishing surveys, while 659 fish were captured during 16
nighttime surveys (Table 3). Overall, a total of 262 site specific HSC observations were
recorded for eight fish species during winter electrofishing surveys in February, March, and
April 2014 (Table 4). Most HSC observations were of coho salmon (120 observations), sockeye
(68 observations), and chum (42 observations) (Table 4).
Few fish were detected during winter underwater video surveys in each Focus Area. No fish
were observed at underwater video sites in FA-104 (Whiskers Creek) or FA-128 (Slough 8A)
during February, March, and April 2014. At FA-138 (Gold Creek), juvenile salmon (60 – 100
mm fork length) were observed during nighttime surveys at Site 138-SL11-22, though species
could not be positively identified. No HSC observations were recorded in association with
underwater video surveys conducted in 2014.
6. DISCUSSION AND CONCLUSION
Winter is a critical period for various life stages of Susitna River fish species and aquatic habitat
conditions can be severe. Susitna River areas that support spawning and egg incubation, juvenile
fish rearing and adult holding are critical winter habitats that may be altered by proposed Project
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 18 September 2014
operations. In general, Project operations are anticipated to result in substantially higher flows in
the winter than under current conditions. Flows at the Gold Creek gage station may range
upwards to 7,000 – 9,000 cfs during the winter period (November – April) depending on Project
operations, compared with existing winter flows that range from around 1,300 – 2,600 cfs (based
on average monthly flows) during those months (Tetra Tech 2013). In addition, unlike current
conditions in which the winter-time represents a stable, base-flow condition, the Project winter-
time flows may vary substantially both hourly and daily due to load-following demands.
The provision of higher flows in the winter-time will mean that areas/habitats that are normally
dewatered and/or disconnected from the main channel may either remain continuously wetted by
Susitna River flow (if wetted during lower load following range) or be periodically wetted if
within the active range of load following. It will also mean that lateral habitats (side channels
and side sloughs) that under current conditions are fed mostly by clear, stable, and comparatively
warm groundwater flow would be subjected to daily/hourly flow increases from the much colder
Susitna River. The frequency and magnitude of these flows into these areas would depend on
the specific breaching conditions of each habitat feature.
The overall objective of the 2013-2014 winter study was to evaluate potential relationships
between mainstem Susitna River stage and the quality and quantity of winter aquatic habitats that
support embryonic, juvenile, and adult life stages of fish species. This information, along with
data and information provided from other resource studies (Ice Processes, Groundwater, Water
Quality, and Fish Distribution and Abundance) will be useful for assessing potential impacts of
winter-time Project operations on aquatic habitats and biota.
The 2013-2014 winter study, which was an expansion of the initial Pilot study completed in
2012-2013 (AEA 2014, Study 8.5 Appendix L), was conducted at three Focus Areas: FA-104
(Whiskers Slough), FA-128 (Slough 8A), and FA-138 (Gold Creek). Each Focus Area was
observed to support salmon spawning in 2013 and each contained a diversity of main channel
and off-channel habitats.
6.1. Water Surface Elevation
Susitna River main channel stage was observed to affect each continuous monitoring site in FA-
104 (Whiskers Creek), FA-128 (Slough 8A), and FA-138 (Gold Creek) during the 2013-2014
winter period. Not surprisingly, water levels in side channel habitats appeared to be most closely
related to Susitna River main channel fluctuations than other habitat types. Water level stage at
side channel sites in Whiskers Side Channel (104-WSC-10), Side Channel 8A (128-SC8A-25),
and Upper Side Channel 11 (138-USC11-09) were closely related to stage at respective main
channel sites (104-MC-40, 128-MC-10, and 138-MC-50). The water level stage at side slough
sites was less responsive to main channel water level fluctuations, particularly when side slough
inlets were not breached by main channel streamflow. Water levels in tributary and upland
slough habitats (e.g., 104-WC-10 and 104-SL3A-70) were the least affected by main channel
stage change among macrohabitat types.
Hydrologic studies conducted during the 1980s observed a similar relationship between stage
and discharge among macrohabitat types and noted that side channels in the Middle Susitna
River were generally more frequently breached by main channel streamflow than other habitats
(Quane et al. 1984). Although stage in side channel and side slough habitats become directly
related to main channel streamflow and stage once the inlet is breached, discharge in non-
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 19 September 2014
breached side slough habitats was observed to be related to main channel streamflow via
intergravel flow through islands and gravel bars (Harza-Ebasco and R&M 1984, Trihey &
Associates and Entrix 1985). It was estimated that one-foot reductions in main channel stage
resulted in changes of 0.3 – 0.6 cfs in non-breached side slough flow, depending on the slough
(Harza-Ebasco and R&M 1984, Trihey & Associates and Entrix 1985).
During the 2013-2014 studies, the inlets to each side channel and side slough monitoring site
were not breached by Susitna River main channel streamflow during instrument installation in
September and October 2013, except the lower inlet to Whiskers Side Channel (Site 104-WSC-
10). However, during Susitna River main channel staging events in each Focus Area, nearly
each monitoring site was affected by high main channel stage via breached side channel or side
slough inlets or due to backwater effects in tributary and upland slough habitats. The durations
of breaching events in side channel and side sloughs were typically short-term as main channel
water levels receded following staging events. As an exception to this, main channel Susitna
River streamflow was diverted through Side Channel 8A (Site 128-SC8A-25) for the remainder
of the winter sampling period following the January 2014 breach event. Similar breaching
events at Slough 8A were observed during Susitna River freeze-up during the 1980s, though the
duration of such events was not documented (Labelle 1984). During the 1980s studies,
breaching of side channel and side slough habitats in the Middle Susitna River by main channel
streamflow was noted to occur most frequently downstream of RM 130 (PRM 102 - PRM 134)
(Labelle 1984). Between Portage Creek (PRM 152) and Gold Creek (PRM 140), main channel
staging was minor during the 1980s and few side channel and side slough breach events were
recorded relative to the lower extent of the Middle Susitna (Labelle 1984).
As noted above, during Project operations, Susitna River streamflow and stage conditions will be
altered relative to the existing conditions by reducing water levels during the open-water period
and increasing discharge during winter. Higher Susitna River discharge during winter may
increase the frequency and magnitude that side channel and side sloughs are breached by cold
main channel streamflow and higher stage may alter the extent of groundwater upwelling in side
channel and off-channel areas. In addition, the daily fluctuations in Susitna River flow could
affect conditions in areas of salmon egg incubation in terms of stage changes that may result in
periodic redd dewatering, as well as changes in temperature (i.e., prolonged egg incubation,
potential freezing during dewatered periods). A better understanding of breaching flows (i.e.,
flows at which surface flows from the main channel Susitna River begin to enter side channel
and off-channel habitats) and relationships between under-ice stage and main channel flows
within each of the Focus Areas will be possible once the open-water and under ice 2-D hydraulic
models are fully developed (AEA 2012, Sections 6.6 and 7.6). In addition, affects of Project
operations on salmon spawning area, in terms of redd dewatering, freezing, channel inlet
breaching, scour, and intergravel water quality (temperature and dissolved oxygen) will be
evaluated as part of the effective spawning area analyses (AEA 2012, Section 8.5).
6.2. Water Quality
Main channel Susitna River intergravel water temperatures appeared to be strongly influenced by
surface water at continuous monitoring sites with temperatures remaining near 0°C for much of
the measurement period at each site. Among continuous monitoring sites in side slough and
upland slough habitats, intergravel temperature were typically warm relative to main channel
conditions (2 – 4°C), which likely indicates the strong influence of groundwater in these habitats.
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Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 20 September 2014
Temperature profiles recorded at side channel monitoring sites suggested highly variable
conditions among side channels in the three Focus Areas. Intergravel temperatures at Site 104-
WSC-30 were near 4°C during January through March 2014, whereas other sites (104-WSC-10
and 128-SC8A-25) exhibited temperatures similar to main channel conditions. Intergravel
temperature in each tributary site (104-WC-10 and 128-SC-05) reflected surface water
temperature and was near 0°C for much of the winter period.
Researchers during the 1980s studies similarly identified off-channel areas with warmer water
temperatures relative to the main channel (Keklak and Withrow 1985, Vining et al. 1985,
Stratton 1986). Temperature data collected during 1984 – 1985 indicated that intergravel water
temperature in the Susitna River main channel and tributaries were closely associated with
surface water temperature, while surface and intergravel temperatures in side sloughs was
generally warmer than the main channel due to groundwater input (Vining et al. 1985).
Temperature variability among side channels was attributed to the complex nature of surface and
groundwater interactions in these habitats (Vining et al. 1985); some side channels exhibited
strong groundwater influence, although breaching by high Susitna River main channel
streamflow can counteract this thermal effect (Vining et al. 1985).
In the 2013-2014 study, most of the monitoring sites affected by high main channel stage in
November and December 2013, intergravel water temperature declined to between 0 – 1°C
during a period in which the site was inundated by main channel streamflow. Exceptions to this
trend occurred at side slough and upland slough habitats that were either not substantially
affected by the increased main channel stage (e.g., Site 104-SL3A-70) or exhibited clear
groundwater influence in terms of warm (4°C), stable intergravel temperature (e.g., Site 138-
SL11-04). The variation in intergravel temperature response to main channel breaching of
Slough 11 between sites 138-SL11-04, 138-SL11-06, and 138-SL11-20 may be an indication of
the localized influence of groundwater and/or that multiple sources of groundwater may be
present within a given habitat.
Studies in the 1980s indicated that the primary groundwater source in side channel and side
slough habitats was derived from lateral infiltration from the Susitna River main channel. The
studies further indicated that the quality of such flow could vary depending upon the intergravel
residence time of the subsurface flow (Trihey & Associates and Entrix 1985). Warm intergravel
temperatures (3 – 5°C) are generally associated with older groundwater (e.g., longer subsurface
path or residence time), which can provide a more stable upwelling source relative to
groundwater of shorter subsurface path (Durst 2001, Malcolm et al. 2005).
During the 2013-2014 study, intergravel dissolved oxygen concentrations at Site 128-SL8A-40
ranged from approximately 5.5 – 11 mg/L during September 2013 through March 2014, while
dissolved oxygen values at Slough 11 Site 138-SL11-04 ranged from approximately 4 – 11
mg/L. The minimum recorded dissolved oxygen values at each site reflect the presumed high
influence of groundwater in Slough 8A and Slough 11. Studies conducted during the 1980s
similarly recorded low intergravel dissolved oxygen values in groundwater-fed side sloughs
(Vining et al. 1985). Mean intergravel dissolved oxygen in April 1983 was 4.6 mg/L at FA-128
(Slough 8A) and 8.5 mg/L at FA-138 (Gold Creek) (Hoffman et al. 1983). Although the low
dissolved oxygen concentrations recorded in side slough habitats may be below the ideal level
for anadromous salmon egg incubation, the conditions present at these sites may be adequate for
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 21 September 2014
egg development depending on intergravel flow, substrate permeability, and water temperature
(Vining et al. 1985, Bjornn and Reiser 1991, Quinn 2005).
Instantaneous measurements of surface water temperature and specific conductance during
February – April 2014 supported the general trend indicated by continuous temperature data of
warmer surface water in off-channel (i.e., side slough and upland slough) areas relative to main
channel and side channel habitats. Although instantaneous water temperature was variable at
many side channel sites, specific conductance within side channels typically reflects that of
Susitna River main channel. At side channel sites in which specific conductance varies from that
of the adjacent main channel (e.g., 138-USC11-12 and 138-USC11-16), surface water may
reflect groundwater that is of a different source than the Susitna River main channel.
Instantaneous measurements at side slough and upland slough habitats typically exhibited higher
temperature and lower conductance values than main channel and side channel areas. However,
exceptions to this trend were present in each Focus Area and may indicate that a portion of the
groundwater source was derived from lateral subsurface flow from the Susitna River main
channel.
Ice cover and thickness observations were recorded in each Focus Area during 2013-2014 IFS
winter studies. As expected, ice cover and thickness was generally greater in FA-104 (Whiskers
Slough) relative to FA-128 (Slough 8A) and FA-138 (Gold Creek), and in main channel and side
channel habitats, in comparison to side slough and upland slough areas. Although ice
measurements were recorded in each macrohabitat, sample locations were associated with
existing (i.e., continuous monitoring sites) or opportunistic sites (i.e., spot measurements) and
thus may not completely reflect the variation in ice conditions. This was particularly evident in
main channel and side channel habitats in which ice appeared to be thicker in areas not sampled.
For additional information on Susitna River ice, refer to Ice Processes ISR Study 7.6 (AEA
2014).
6.3. Fish Observations
Fish presence was recorded during both day and night periods in open-water areas during
electrofishing surveys (see also AEA 2014b). Diel differences in fish behavior are common
among fish species, particularly during winter, but information specific to the Susitna River is
sparse. In general, when day length is short and water temperatures are low, fish activity often
shifts from diurnal to nocturnal periods, such that individuals become inactive and/or hide during
the day to minimize energy expenditure and reduce predation risk (Roni and Fayram 2000,
Quinn 2005, Reeves et al. 2009). The presence of ice cover, however, may mitigate such
behavioral shifts. During a winter study of the effect of ice cover on fish behavior, greater fish
activity and foraging was observed in the presence of ice cover relative to its absence (Watz
2013). Monitoring of fish activity and behavior during future day and nighttime winter surveys
using underwater video, sonar and fish capture techniques will help elucidate potential winter
behavioral patterns exhibited by fish species in the Susitna River.
A total of 262 HSC observations were recorded for eight species in FA-104 (Whiskers Slough),
FA-128 (Slough 8A), FA-138 (Gold Creek), and FA-141 (Indian River). HSC/HSI curves for
fish species will be developed to describe the response of fish to relatively short-term flow
fluctuations (i.e., ramping).
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 22 September 2014
7. PLANS FOR 2015
The 2014-2015 IFS winter studies represent the second complete year of studying the winter
habitat conditions within the three Focus Areas (FA-104 [Whiskers Slough], FA-128 [Slough
8A], FA-138 [Gold Creek]), and in conjunction with data collected as part of the 2012-2013 Pilot
winter studies, will provide information regarding the inter-annual variability of these conditions.
These studies will be performed in conjunction with the winter studies to be performed by FDA
and Groundwater resource disciplines.
The objectives of the 2014-2015 IFS winter studies remain the same as stated above and are to
evaluate potential relationships between mainstem Susitna River stage and the quality and
quantity of winter aquatic habitats that support embryonic, juvenile, and adult life stages of fish
species and to record fish behavior and habitat utilization in support of HSC/HSI development.
Specific tasks for the 2014-2015 work are identified in Section 2. The general approach of the
2014-2015 IFS winter study will be similar to the 2013-2014 effort (see Section 4), in terms of
Focus Areas studied (FA-104 [Whiskers Slough], FA-128 [Slough 8A], and FA-138 [Gold
Creek]) and the general level of effort. Specific tasks include:
Continuous stage and water quality (temperature and dissolved oxygen) monitoring
will occur at FA-104 (Whiskers Slough), FA-128 (Slough 8A), and FA-138 (Gold
Creek) through the period of salmon egg incubation (September 2014 – April 2015)
(Figure 1).
Stage and water temperature data (surface and intergravel) will be continuously
monitored at main channel and off-channel sites in each of FA-104 (Whiskers
Slough), FA-128 (Slough 8A), and FA-138 (Gold Creek). Monitoring sites within
each Focus Area will be distributed among habitat types, at locations of known
salmon spawning, and at sites with and without groundwater influence.
Intergravel dissolved oxygen will be continuously recorded at known salmon
spawning locations.
Fish observation and capture efforts will be performed at available habitat types in
each of FA-104 (Whiskers Slough), FA-128 (Slough 8A), and FA-138 (Gold Creek);
additional sites outside of these Focus Areas will be sampled based on observed fish
distribution, site access, weather conditions, and personnel safety.
Fish activity and behavior will be monitored using underwater video equipment to
discern potential patterns in activity related to diurnal and seasonal periodicity and/or
habitat (e.g., side channel, side slough).
Site-specific habitat suitability criteria (HSC) for juvenile and adult fish will be
recorded using electrofish capture methods in open-water areas and underwater video
in ice covered habitats.
Instantaneous surface water quality measurements (temperature, dissolved oxygen,
specific conductance) and ice thickness data will be recorded in association with
maintenance of continuous stage and water quality monitoring sites and fish
observation and capture efforts.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 23 September 2014
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FERC Project No. 14241 Page 29 September 2014
9. TABLES
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 30 September 2014
Table 1. The period of data collection at continuous water level, water quality and barometric pressure monitoring sites
in FA-104 (Whiskers Slough), FA-128 (Slough 8A) and FA-138 (Gold Creek) for 2013-2014 IFS winter studies.
Focus
Area Site Instrument Type Period of Record Comment
104 104-BARO Barometric Sept 2013 - Current1
104-MC-40 Pressure transducer, Temperature Sept 2013 - June 2014 104-MC-50 Pressure transducer Feb 2014 - April 2014
104-SL3A-70 Pressure transducer, Temperature Sept 2013 - April 2014
104-SL3B-10 Pressure transducer Sept 2013 - Current1 104-SL3B-10 Temperature Sept 2013 - March 2014
104-WC-10 Pressure transducer, Temperature Sept 2013 - June 2014 2013 salmon spawn site
104-WESC-10 Pressure transducer Oct 2013 - June 2014 104-WESC-10 Temperature Sept 2013 - March 2014
104-WESC2-12 Temperature March 2014 - Current1 2013 salmon spawn site
104-WSC-10 Pressure transducer Sept 2013 - June 2014 2013 salmon spawn site
104-WSC-10 Temperature Sept 2013 - March 2014 2013 salmon spawn site
104-WSC-30 Pressure transducer Sept 2013 - June 2014 2012 salmon spawn site
104-WSC-30 Temperature Sept 2013 - Current1 2012 salmon spawn site
104-WSL-20 Pressure transducer, Temperature Sept 2013 - June 2014 2013 salmon spawn site
128 128-BARO Barometric Sept 2013 - Current1
128-MC-10 Pressure transducer Sept 2013 - April 2014 128-MC-10 Temperature Sept 2013 - Current1
128-SC-05 Temperature Sept 2013 - March 2014 2013 salmon spawn site
128-SC8A-24 Temperature March 2014 - Current1 128-SC8A-25 Pressure transducer, Temperature Sept 2013 - April 2014 2013 salmon spawn site
128-SL8A-15 Temperature Sept 2013 - Current1 2013 salmon spawn site
ESSFA128-12 Pressure transducer Sept 2013 - March 2014
128-SL8A-40 Dissolved oxygen Sept 2013 - March 2014 2013 salmon spawn site
128-SL8A-40 Pressure transducer, Temperature Sept 2013 - Current1 2013 salmon spawn site
128-SLA-20 Pressure transducer, Temperature Sept 2013 - Current1 2013 salmon spawn site
128-US1-10 Pressure transducer, Temperature Sept 2013 - March 2014
128-US2-15 Pressure transducer, Temperature Sept 2013 - March 2014
138 138-BARO Barometric Sept 2013 - Current1
138-MC-50 Pressure transducer Sept 2013 - April 2014 138-MC-50 Temperature Sept 2013 - March 2014
138-SL11-04 Dissolved oxygen Sept 2013 - April 2014 2013 salmon spawn site
138-SL11-04 Pressure transducer, Temperature Sept 2013 - Current1 2013 salmon spawn site
138-SL11-06 Temperature Sept 2013 - Current1 2013 salmon spawn site
138-SL11-20 Pressure transducer, Temperature Sept 2013 - Current1
138-SL12-10 Pressure transducer, Temperature Sept 2013 - Current1 Inaccessible during winter
138-SL13-04 Pressure transducer Feb 2014 - Current1 2013 salmon spawn site
138-SL13-04 Temperature March 2014 - Current1 2013 salmon spawn site
138-SL13-05 Pressure transducer, Temperature Sept 2013 - Current1 2013 salmon spawn site;
Inaccessible in winter
138-USC11-09 Pressure transducer, Temperature Sept 2013 - Current1 2013 salmon spawn site
1 Instruments are collecting data as of August 2014; approximate retrieval timing will be September 2014.
2 The ESSFA128-1 station is operated and maintained as part of the Groundwater Study.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 31 September 2014
Table 2. Instantaneous measurements of surface and groundwater temperature, specific conductance, dissolved oxygen
concentration, and ice thickness at sites in FA-104 (Whiskers Creek), FA-128 (Slough 8A), and FA-138 (Gold Creek)
during February and March 2014. Surface water measurements were recorded at mid-column water depth and
groundwater was measured approximately 20 cm below the substrate surface at intergravel and near the surface at
groundwater wells and bank seep locations.
Site1 Water Body
Habitat
Type2 Date
Water
Temperature
(°C)
Specific
Conductance
(µS/cm)
Dissolved
Oxygen
(mg/L)
Ice
thickness
(ft)
FA-104 (Whiskers Slough)
104-MC-50 Main channel MC 3/6/14 0.2 256.0 na 3.6
104-MC-50 Main channel MC 2/7/14 0.1 227.0 na 3.5
104-WSC-30 Whiskers SC SC 3/5/14 0.9 235.0 10.86 0
104-WSC-10 Whiskers SC SC 3/6/14 1.0 125.3 6.53 1.0 - 4.0
104-WESC2-12 Whiskers East Side Channel SC 3/7/14 0.9 237.0 11.06 0.1 – 0.4
104-WESC-20 Whiskers East Side Channel SC 3/7/14 0.1 265.0 na na
104-WESC-10 Whiskers East Side Channel SC 3/7/14 0.2 264.0 na 2.2
104-SL3B-10 Slough 3B SC 3/5/14 1.6 90.9 8.98 0
104-WSL-50 Whiskers Slough SS 3/7/14 2.8 75.5 2.40 0.2 – 0.8
104-WSL-40 Whiskers Slough SS 3/7/14 1.0 70.5 6.05 1.1
104-WSL-20 Whiskers Slough SS 3/4/14 0.3 32.9 13.12 0.2
104-CFSL-15 Chicken Foot Slough SS 3/5/14 1.7 200.5 6.63 0 – 0.3
104-WC-20 Whiskers Creek TR 2/4/14 0.2 35.7 14.21 0.3
104-WC-10 Whiskers Creek TR 3/5/14 0.6 32.3 13.21 na
104-SL3A-70 Slough 3A US 3/7/14 0.6 96.3 7.74 na
104-SL3A-11* Groundwater seep in Slough 3A US* 3/5/14 1.0* 110.7* 0.21* 0
104-SL3A-10 Slough 3A US 3/5/14 0.8 92.0 9.53 0
ESGFA104-9-W1* Groundwater well GW* 2/6/14 2.3 158.8 1.15 na
ESGFA104-10-W1* Groundwater well GW* 2/6/14 1.8* 124.0* 3.18* na
FA-128 (Slough 8A)
128-MC-10 Main channel MC 2/15/14 0.1 284.1 na 3.2
128-SC8A-24 Side Channel 8A SC 3/14/14 0.5 260.0 13.34 0
128-SC8A-35 Side Channel 8A SC 3/13/14 0.2 268.0 na 0
128-SSC-14 Skull Side Channel SC 3/16/14 0.1 264.0 na 0
128-SSC-15 Skull Side Channel open lead SC 3/16/14 1.1 262.0 11.15 0
128-HMSC-01 Half Moon Side Channel SC 3/16/14 0.3 270.0 na 2.0
128-SL8A-15 Slough 8A SS 3/14/14 1.7 207.9 11.55 0.4
128-SL8A-40 Slough 8A SS 3/16/14 1.2 214.8 11.75 0
128-SL8A-40* Intergravel site in Slough 8A SS* 3/16/14 4.5* 58.6* 4.01* 0
128-SL8A-40 Slough 8A SS 2/15/14 0.3 263.0 12.94 0
128-SLA-20 Slough A SS 3/14/14 1.2 165.1 12.63 0
128-US1-10 Upland Slough 1 US 3/15/14 0.2 125.9 na 2.1
128-US2-15 Upland Slough 2 US 3/13/14 1.6 193.6 9.76 0.6
128-US3-01 Upland Slough 3 US 3/15/14 2.4 191.5 11.50 0
128-US3-05 Upland Slough 3 US 3/13/14 4.1 191.3 6.91 0
128-HMSL-20 Half Moon Slough US 3/14/14 2.1 226.0 6.84 1.4
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 32 September 2014
Site1 Water Body
Habitat
Type2 Date
Water
Temperature
(°C)
Specific
Conductance
(µS/cm)
Dissolved
Oxygen
(mg/L)
Ice
thickness
(ft)
128-SC-05 Skull Creek TR 2/16/14 1.1 162.9 7.98 1.5
ESGFA128-13-W1* Groundwater well GW* 3/16/14 0.6* 269.0* 7.82* na
ESGFA128-18-W1* Groundwater well GW* 3/16/14 3.0* 170.0* 4.86* na
FA-138 (Gold Creek)
138-MC-50 Main channel MC 2/9/14 0.3 250.0 13.34 0 – 1.5
138-MC-50 Main channel MC 3/9/14 0.2 269.0 na 0 – 1.5
138-MC-70 Main channel MC 2/11/14 0.2 245.0 na na
138-USC11-09 Upper Side Channel 11 SC 2/9/14 0.8 203.9 11.67 0.2
138-USC11-12* Left bank seep; Upper SC 11 SC* 2/10/14 2.5* 135.2* 8.23* 0
138-USC11-16* Right bank seep; Upper SC 11 SC* 2/10/14 3.3* 120.5* 6.69* 0
138-USC11-40 Upper Side Channel 11 SC 3/9/14 0.2 324.0 na 2.5
138-LSC11-11 Lower Side Channel 11 SC 2/10/14 0.8 261.0 12.62 0
138-LSC11-11* Left bank seep; Lower SC 11 SC* 2/10/14 2.6* 114.4* 8.46* 0
138-LSC11-12* Right bank seep; Lower SC 11 SC* 2/10/14 1.5* 288.0* 10.18* 0
138-LSC11-20 Lower Side Channel 11 SC 2/10/14 0.1 275.0 na 2.0
138-SC12-05 Side Channel 12 SC 3/12/14 1.9 264.0 10.41 0.2
138-SC14-25 Side Channel 14 SC 3/11/14 0.2 261.0 na 2.0
138-SL11-04* Intergravel site in Slough 11 SS 3/12/14 3.3* 190.1* 10.00* 0
138-SL11-04 Slough 11 SS 3/12/14 2.5 272.0 11.33 0
138-SL11-10 Slough 11 SS 3/12/14 1.9 293.0 11.84 0
138-SL11-11* Left bank seep; Slough 11 SS 3/12/14 1.1* 290.0* 9.70* 0
138-SL11-20 Slough 11 SS 3/10/14 1.3 296.0 11.82 0.5
138-SL11-50 Slough 11 SS 2/11/14 1.2 291.0 11.71 0
138-SL11-60 Slough 11 SS 3/10/14 2.1 315.0 12.02 0
138-SL12-10 Slough 12 US 2/9/14 0.1 103.3 na na
138-SL13-04 Slough 13 US 3/12/14 2.2 256.0 7.16 0.5
138-SL13-15 Slough 13 US 3/12/14 1.6 202.6 7.98 0.2
138-US14-20 Seepage; Upland Slough 14 US 3/11/14 3.3 64.2 11.71 0
138-GC-05 Gold Creek TR 2/11/14 0.3 376 13.65 na
ESGFA138-3-W1* Groundwater well GW* 3/12/14 2.2* 254* 9.84* na
ESGFA138-4-W1* Groundwater well GW* 3/12/14 1.4* 185* 7.04* na
1 Asterisks (*) indicate measurements of groundwater at intergravel dissolved oxygen monitoring sites (approximately 20 cm below the
substrate surface), groundwater wells, or bank seepage.
2 MC = Main Channel, SC = Side Channel, SS = Side slough, US = Upland Slough TR = Tributary, GW = Groundwater monitoring well;
habitat designations are based on 2012 Middle Susitna River remote line habitat mapping (HDR 2013).
na – Data are not available.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 33 September 2014 Table 3. Total number of fish captured by species and lifestage during daytime and nighttime electrofishing surveys conducted in FA-104 (Whiskers Slough), FA-128 (Slough 8A), FA-138 (Gold Creek), and FA-141 (Indian River) in February, March, and April 2014. Nighttime surveys are italicized. FA Site Survey Date Habitat Type2 Capture totals, by species and lifestage1 Total Count Chinook, Juvenile Sockeye, Juvenile Chum, Juvenile Coho, Juvenile Rainbow Trout, Juvenile Grayling, Juvenile Longnose sucker, Juvenile Lamprey species, Juvenile Sculpin species, Juvenile, Adult 104 104-WSC-12 3-Apr SC 0 0 0 0 0 0 1 0 0 1 104-WSC-30 1-Apr SC 0 0 0 0 0 0 0 0 0 0 104-WESC-01 4-Apr SC 0 0 0 0 0 0 0 0 0 0 104-SL3B-01 5-Mar SC 2 0 0 21 0 1 0 0 24 48 7-Mar SC 0 0 0 1 0 0 1 0 6 8 1-Apr SC 0 0 0 5 0 0 1 0 0 6 2-Apr SC 0 0 0 15 0 0 0 0 0 15 104-SL3A-10 5-Mar US 0 0 0 28 0 0 0 0 2 30 7-Mar US 0 0 0 4 0 0 0 0 1 5 2-Apr US 0 0 0 16 1 0 0 0 0 17 4-Apr US 0 0 0 3 0 0 0 0 0 3 104-WC-25 5-Feb TR 0 0 0 2 1 0 0 0 4 7 3-Apr TR 15 0 0 17 0 0 0 2 0 32 128 128-SSC-10 10-Apr SC 0 3 0 0 0 0 0 0 0 3 128-SC8A-05 12-Apr SC 0 0 1 0 0 0 0 0 0 1 128-SL8A-28 11-Apr SS 0 154 4 2 0 0 0 0 0 160 128-SL8A-30 14-Mar SS 0 0 8 0 0 0 0 0 44 52 14-Mar SS 0 2 4 0 0 0 0 0 36 42 128-SLA-01 12-Apr US 0 1 18 2 0 0 0 0 0 21 128-SLA-20 12-Apr US 5 4 0 8 0 0 0 0 0 17 128-US3-01 14-Mar US 0 2 1 2 2 0 0 0 0 7 15-Mar US 0 0 2 2 0 0 0 0 0 4 12-Apr US 0 6 0 3 0 0 0 0 0 9 128-HMSL-01 10-Apr US 0 0 0 0 0 0 0 0 0 0 128-HMSL-30 10-Apr US 0 0 0 0 0 0 0 0 0 0
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 34 September 2014 FA Site Survey Date Habitat Type2 Capture totals, by species and lifestage1 Total Count Chinook, Juvenile Sockeye, Juvenile Chum, Juvenile Coho, Juvenile Rainbow Trout, Juvenile Grayling, Juvenile Longnose sucker, Juvenile Lamprey species, Juvenile Sculpin species, Juvenile, Adult 138 138-MC-30 9-Apr MC 1 0 0 1 0 0 0 0 0 2 138-USC11-20 10-Mar SC 0 0 0 3 0 0 0 0 2 5 11-Mar SC 0 0 3 1 2 0 0 0 3 9 138-USC11-15 10-Feb SC 0 0 0 0 0 0 0 0 0 0 10-Feb SC 1 0 0 0 0 0 0 0 0 1 138-USC11-22 7-Apr SC 0 0 68 5 0 0 0 0 0 73 9-Apr SC 0 0 44 0 0 0 0 0 0 44 138-SL11-25 9-Feb SS 0 1 0 0 0 0 0 0 23 24 10-Feb SS 0 6 0 0 0 0 0 0 19 25 10-Mar SS 0 1 0 0 0 0 0 0 29 30 10-Mar SS 1 28 0 14 0 0 0 0 67 110 6-Apr SS 0 0 0 2 0 0 0 0 0 2 8-Apr SS 0 51 0 33 0 0 0 0 0 84 138-SL11-04 7-Apr SS 0 1 0 0 0 0 0 0 0 1 138-SL11-10 12-Mar SS 0 0 0 0 0 0 0 0 2 2 7-Apr SS 0 1 0 0 0 0 0 0 0 1 138-LSC11-10 10-Feb SC 0 0 0 0 0 0 0 0 1 1 10-Feb SC 0 0 0 0 0 0 0 0 4 4 7-Apr SC 0 0 1 0 0 0 0 0 0 1 141 141-MC-30 9-Apr MC 1 0 0 3 0 0 0 0 0 4 Total Count 26 261 154 193 6 1 3 2 267 911 1 Juvenile lifestage represents fish less than 150 mm fork length for all species other than sculpin. 2 SS = Side slough, SC = Side Channel, TR = Tributary, US = Upland Slough; habitat designations are based on 2012 Middle Susitna River remote line habitat mapping (HDR 2013).
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 35 September 2014
Table 4. Total number of HSC observations recorded during electrofish sampling in February, March, and April 2014 by
fish species and lifestage.
Species Lifestage1
FA-104
(Whiskers
Slough)
FA-128
(Slough 8A)
FA-138
(Gold Creek)
FA-141
(Indian
River)
Total
Count
Chinook salmon Fry 13 0 0 1 14
Juvenile 2 3 1 0 6
Sockeye salmon Fry 1 30 4 0 35
Juvenile 0 0 33 0 33
Chum salmon Fry 0 17 25 0 42
Coho salmon Fry 25 7 2 1 35
Juvenile 47 7 32 2 88
Rainbow trout Juvenile 2 0 2 0 4
Arctic grayling Juvenile 1 0 0 0 1
Longnose sucker Juvenile 2 0 0 0 2
Arctic lamprey Juvenile 2 0 0 0 2
Total Count 95 64 99 4 262
1 Fry consist of fish less than 60 mm fork length; juvenile lifestage represents fish between 60 mm and 150 mm fork length.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 36 September 2014
10. FIGURES
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 37 September 2014 Figure 1. Location of Focus Areas used for 2013-2014 IFS winter data collection.
TECHNICAL MEMORANDUM ADDENDUM 2013-2014 INSTREAM FLOW WINTER STUDIES Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 2 December 2014 Revised Figure 2. Locations of 2013-2014 winter sites for continuous and instantaneous water quality monitoring, water level monitoring, and fish sampling in FA-104 (Whiskers Slough).
TECHNICAL MEMORANDUM ADDENDUM 2013-2014 INSTREAM FLOW WINTER STUDIES Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 3 December 2014 Revised Figure 3. Locations of 2013-2014 winter sites for continuous and instantaneous water quality monitoring, water level monitoring, and fish sampling in FA-128 (Slough 8A).
TECHNICAL MEMORANDUM ADDENDUM 2013-2014 INSTREAM FLOW WINTER STUDIES Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 4 December 2014 Revised Figure 4. Locations of 2013-2014 winter sites for continuous and instantaneous water quality monitoring, water level monitoring, and fish sampling in FA-138 (Gold Creek).
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 41 September 2014
Figure 5. Comparison of change in normalized water surface elevation among continuous monitoring sites in FA-104
(Whiskers Slough) during September 2013 through June 2014. Elevations were normalized to zero on October 1, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 42 September 2014
Figure 6. Comparison of change in normalized water surface elevation among continuous monitoring sites in FA-128
(Slough 8A) during September 2013 through April 2014. Elevations were normalized to zero on September 30, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 43 September 2014
Figure 7. Comparison of change in normalized water surface elevation among continuous monitoring sites in FA-138
(Gold Creek) during September 2013 through April 2014. Elevations were normalized to zero on September 30, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 44 September 2014
Figure 8. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9 in),
and 35 cm (13.8 in) relative to normalized water surface elevation at Susitna River main channel (104-MC-40) and
Whiskers Side Channel (104-WSC-10) continuous monitoring sites in FA-104 (Whiskers Slough) during September 2013 -
June 2014. Water elevations were normalized to zero on October 1, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 45 September 2014
Figure 9. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9 in),
and 35 cm (13.8 in) relative to normalized water surface elevation at Whiskers Side Channel (104-WSC-30) and Whiskers
East Side Channel (104-WESC-10) continuous monitoring sites in FA-104 (Whiskers Slough) during September 2013 -
June 2014. Water elevations were normalized to zero on October 1, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 46 September 2014
Figure 10. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at upland slough (104-SL3A-70) and side channel
(104-SL3B-10) continuous monitoring sites in FA-104 (Whiskers Slough) during September 2013 - June 2014. Water
elevations were normalized to zero on October 1, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 47 September 2014
Figure 11. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at Whiskers Creek (104-WC-10) and Whiskers
Slough (104-WSL-20) continuous monitoring sites in FA-104 (Whiskers Slough) during September 2013 - June 2014.
Water elevations were normalized to zero on October 1, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 48 September 2014
Figure 12. Instantaneous measurements of surface water temperature and specific conductance recorded at sites in FA-
104 (Whiskers Slough) during February and March 2014, by macrohabitat type.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 49 September 2014
Figure 13. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at Susitna River main channel (128-MC-10) and
Side Channel 8A (128-SC8A-25) continuous monitoring sites in FA-128 (Slough 8A) during September 2013 - April 2014.
Water elevations were normalized to zero on September 30, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 50 September 2014
Figure 14. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at Slough 8A (128-SL8A-40 and 128-SL8A-15)
continuous monitoring sites in FA-128 (Slough 8A) during September 2013 - April 2014. Water elevations were
normalized to zero on September 30, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 51 September 2014
Figure 15. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at Upland Slough 2 (128-US2-15) and Upland
Slough 1 (128-US1-10) continuous monitoring sites in FA-128 (Slough 8A) during September 2013 - April 2014. Water
elevations were normalized to zero on September 30, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 52 September 2014
Figure 16. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at Skull Creek (128-SC-05) and Slough A (128-
SLA-20) continuous monitoring sites in FA-128 (Slough 8A) during September 2013 - April 2014. Elevations were
normalized to zero on September 30, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 53 September 2014
Figure 17. Continuous intergravel dissolved oxygen concentration and water temperature data recorded approximately
20 cm (7.9 in) below the substrate surface at in FA-128 (Slough 8A; Site SL8A-40) and during September 2013 - April
2014.
Figure 18. Instantaneous measurements of surface water temperature and specific conductance recorded at sites in FA-
128 (Slough 8A) during February and March 2014, by macrohabitat type.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 54 September 2014
Figure 19. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at Susitna River main channel (138-MC-10) and
Upper Side Channel 11 (138-USC11-09) continuous monitoring sites in FA-138 (Gold Creek) during September 2013 -
March 2014. Water elevations were normalized to zero on September 30, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 55 September 2014
Figure 20. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at Slough 11 (138-SL11-06 and 138-SL11-04)
continuous monitoring sites in FA-138 (Gold Creek) during September 2013 - March 2014. Water elevations were
normalized to zero on September 30, 2013.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 56 September 2014
Figure 21. Water temperature recorded above the substrate surface and at intergravel depths of 5 cm (2 in), 20 cm (7.9
in), and 35 cm (13.8 in) relative to normalized water surface elevation at Slough 11 continuous monitoring site 138-SL11-
20 in FA-138 (Gold Creek) during September 2013 - March 2014. Elevations were normalized to zero on September 30,
2013.
Figure 22. Continuous intergravel dissolved oxygen concentration and water temperature data recorded approximately
20 cm (7.9 in) below the substrate surface at FA-138 (Gold Creek; Site 138-SL11-04) during September 2013 - April 2014.
TECHNICAL MEMORANDUM 2013-2014 INSTREAM FLOW WINTER STUDIES
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 57 September 2014
Figure 23. Instantaneous measurements of surface water temperature and specific conductance recorded at sites in FA-
138 (Gold Creek) during February and March 2014, by macrohabitat type.