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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
SuWa 250
Groundwater study (Study 7.5), preliminary groundwater and surface-water
relationships in lateral aquatic habitats within focus areas FA-128 (Slough
8A) and FA-138 (Gold Creek) in the middle Susitna River, technical
memorandum
Author(s) – Personal:
Author(s) – Corporate:
Geo-Watershed Scientific and R2 Resource Consultants, Inc.
AEA-identified category, if specified:
September 30, 2014 technical memorandum filings
AEA-identified series, if specified:
Series (ARLIS-assigned report number): Existing numbers on document:
Susitna-Watana Hydroelectric Project document number 250
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 C
Document type: Pagination:
Technical memorandum 136 p. in various pagings
Related work(s): Pages added/changed by ARLIS:
Cover letter to this report: Susitna-Watana Hydroelectric Project,
FERC Project no. 14241-000; Third set of 2014 technical
memoranda for Initial Study Plan meeting. (SuWa 247)
Attachments A-B (SuWa 24 8-249) and D-F (SuWa 251-253)
Added cover letter (3 pages)
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 30, 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
Third Set of 2014 Technical Memoranda for Initial Study Plan Meetings
Dear Secretary Bose:
As the Alaska Energy Authority (AEA) explained in its September 17, 2014 filing
with the Federal Energy Regulatory Commission (Commission or FERC) for the
proposed Susitna-Watana Hydroelectric Project, FERC Project No. 14241 (Project), the
June 3, 2014 Initial Study Report (ISR) provided for AEA to prepare certain technical
memoranda and other information based on 2014 work. In accordance with Commission
Staff direction, on September 17 and September 26, AEA filed and distributed the first
and second sets of technical memoranda and other information generated during the 2014
study season.
With this letter, AEA is filing and distributing the third set of technical
memoranda generated during the 2014 study season, as described below.
This third set of technical memoranda includes:
• Attachment A: Baseline Water Quality Study (Study 5.5) and Water Quality
Modeling Study (Study 5.6), Water Quality and Lower River Modeling
Technical Memorandum. This technical memorandum evaluates water quality
data collected during 2013 and 2014 for adequacy in representation of current
riverine conditions. This Technical Memorandum further includes an
assessment of whether to extend the Water Quality Modeling Study’s riverine
model below PRM 29.9.
• Attachment B: Mercury Assessment and Potential for Bioaccumulation Study
(Study 5.7), Evaluation of Continued Mercury Monitoring Beyond 2014
Technical Memorandum. This technical memorandum evaluates the need for
continued monitoring of mercury data beyond 2014 and whether the existing
data collection efforts are sufficient to satisfy objectives for characterizing
baseline mercury conditions in the Susitna River and tributaries (Revised
Study Plan (RSP) Section 5.7.1).
2
• Attachment C: Groundwater Study (Study 7.5), Preliminary Groundwater and
Surface-Water Relationships in Lateral Aquatic Habitats within Focus Areas
FA-128 (Slough 8A) and FA-138 (Gold Creek) in the Middle Susitna River
Technical Memorandum. This technical memorandum provides an overview
of the types of data and information that are being collected to support the
Task 6 activities of the Groundwater Study, and describes the methods and
techniques that are being applied in analyzing the data leading to development
of response functions to be used for evaluating Project operational
effects. The TM centers on the analysis for FA-128 (Slough 8A) and to a
lesser extent FA-138 (Gold Creek) and represents an expansion of the
presentation materials provided during the Proof of Concept meetings held on
April 15-17, 2014.
• Attachment D: Groundwater Study (Study 7.5), Groundwater and Surface-
Water Relationships in Support of Riparian Vegetation Modeling Technical
Memorandum. This technical memorandum provides an overview of the
types of data and information that are being collected to support the Task 5
activities within the Groundwater Study, and describes the methods and
techniques that are being applied in analyzing the data leading to development
of response functions for evaluating Project operational effects. The TM
provides analysis objectives for FA-115 (Slough 6A) as a primary example of
upland versus riverine dominated groundwater conditions. Additional
examples are shown for FA-128 (Slough 8A) and FA-138 (Gold Creek).
• Attachment E: Salmon Escapement Study (Study 9.7), 2014 Implementation
and Preliminary Results Technical Memorandum. This technical
memorandum describes 2014 implementation (including methods and
variances) of and preliminary results from the Salmon Escapement Study.
• Attachment F: Cook Inlet Beluga Whale Study Plan (Study 9.17), 2015
Implementation Plan Technical Memorandum. This implementation plan
describes the methods for study activities proposed for 2015 that would
implement the Cook Inlet Beluga Whale Study (instead of those described in
RSP Section 9.17.1).
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.
3
Sincerely,
Wayne Dyok
Project Manager
Alaska Energy Authority
Attachments
cc: Distribution List (w/o Attachments)
Attachment C
Groundwater Study (Study 7.5), Preliminary Groundwater and Surface-Water Relationships in
Lateral Aquatic Habitats within Focus Areas FA-128 (Slough 8A) and FA-138 (Gold Creek) in
the Middle Susitna River Technical Memorandum
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Groundwater Study
(Study 7.5)
Preliminary Groundwater and Surface-Water
Relationships in Lateral Aquatic Habitats within
Focus Areas FA-128 (Slough 8A) and FA-138 (Gold
Creek) in the Middle Susitna River
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
Geo-Watersheds Scientific and R2 Resource Consultants, Inc.
September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
TABLE OF CONTENTS
1. Introduction ........................................................................................................................1
1.1. Project Description.............................................................................................1
1.2. Study Background ..............................................................................................2
1.2.1. Importance of Groundwater to Fish Habitat in the Susitna River .. 2
1.2.2. Susitna-Watana Project Groundwater Studies ................................ 4
1.3. Technical Memorandum Objectives ..................................................................4
2. Study Area ..........................................................................................................................4
3. Methods ...............................................................................................................................5
3.1. Hydrology Observations ....................................................................................5
3.1.1. Water Surface Elevations and Water Temperature Measurements 5
3.1.2. Discharge Measurements ................................................................ 6
3.1.3. Land-based and Aerial Photographic Imagery ............................... 7
3.2. Analysis Methods...............................................................................................8
3.2.1. Empirical Analysis Methods ........................................................... 8
3.2.2. Functional Relationships with Susitna River Flow ......................... 8
3.2.3. Groundwater Modeling ................................................................... 9
3.3. Deviations from Study Plan .............................................................................10
4. Results ...............................................................................................................................10
4.1. Hydrology Observations ..................................................................................10
4.1.1. FA-128 (Slough 8A) ..................................................................... 11
4.1.2. FA-138 (Gold Creek) .................................................................... 13
4.2. Functional Relationships of Surface and Groundwater Levels to Susitna River
Flow .................................................................................................................14
4.2.1. FA-128 (Slough 8A) ..................................................................... 14
4.2.2. FA-138 (Gold Creek) .................................................................... 15
4.3. GW/SW Relationships to Aquatic Habitat Functions ......................................15
4.3.1. ESGFA128-13 – Middle Side Channel 8A– Downwelling
Dynamics ...................................................................................... 16
4.3.2. ESGFA138-2 – Upper Side Channel 11 – Upwelling Dynamics . 16
5. Groundwater and Surface water relationships in Lateral Habitats ...........................17
6. Plans for 2015 ...................................................................................................................19
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
7. References .........................................................................................................................20
8. Tables ................................................................................................................................25
9. Figures ...............................................................................................................................27
LIST OF TABLES
Table 3.1-1. Locations of discharge measurements recorded in FA-104 (Whiskers Slough), FA-
128 (Slough 8A) and FA-138 (Gold Creek) during March and April 2014. ........................ 25
Table 3.1-2. Instream Flow Study discharge measurement summary table. ............................... 26
LIST OF FIGURES
Figure 2.0-1. Susitna Watershed basin boundaries, showing the Project designation of upper,
middle and lower river segments. ......................................................................................... 28
Figure 2.0-2. Susitna Watershed Middle River Segment, with geomorphic reaches and Focus
Areas indicated. ..................................................................................................................... 29
Figure 2.0-3. General location of FA-128 (Slough 8A) Focus Area, showing major data
collection stations and aquatic and riparian transects. .......................................................... 30
Figure 2.0-4. Inset A shows locations of aquatic transect stations with continuously measured
parameters at FA-128 (Slough 8A) Focus Area. .................................................................. 31
Figure 2.0-5. Inset B shows locations of aquatic transect stations with continuously measured
parameters at FA-128 (Slough 8A) Focus Area. .................................................................. 32
Figure 2.0-6. Inset C shows locations of aquatic transect stations with continuously measured
parameters at FA-128 (Slough 8A) Focus Area. .................................................................. 33
Figure 2.0-7. General location of FA-138 (Gold Creek) Focus Area, showing major data
collection stations and aquatic and riparian transects. .......................................................... 34
Figure 2.0-8. Inset A shows locations of aquatic transect stations with continuously measured
parameters at FA-138 (Gold Creek) Focus Area. ................................................................. 35
Figure 2.0-9. Inset B shows locations of aquatic transect stations with continuously measured
parameters at FA-138 (Gold Creek) Focus Area. ................................................................. 36
Figure 3.2-10. Period of Record Flow Conditions for Susitna River at Gold Creek and Annual
Hydrologic Periods. .............................................................................................................. 37
Figure 3.2-11. 2013 Discharge hydrograph for the Susitna River at Gold Creek (USGS 1529200)
with selected periods (points of interest) shown used for response function analysis. ......... 37
Figure 3.2-12. 2014 Discharge hydrograph for the Susitna River at Gold Creek (USGS 1529200)
with selected periods (points of interest) shown used for response function analysis. ......... 38
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 4.1-13. Cross-section diagram showing Lower Aquatic Transect on Middle Side Channel
8A, with groundwater stations ESGFA128-13, ESGFA128-20, and ESGFA128-21. Wells
are shown and water levels and channel water level for April 22, 2014. ............................. 38
Figure 4.1-14. Groundwater Station ESGFA128-13 groundwater levels in wells adjacent to
Middle Side Channel 8A and surface-water stage in Middle Side Channel 8A, and
groundwater levels from wells at ESGFA128-20 and ESGFA128-21. ................................ 39
Figure 4.1-15. Groundwater Station ESGFA128-13 groundwater temperature in wells adjacent
to Middle Side Channel 8A and surface-water temperature in Middle Side Channel 8A, and
groundwater temperature from wells at ESGFA128-20 and ESGFA128-21. ...................... 39
Figure 4.1-16. Groundwater Station ESGFA128-13 select streambed temperature profile
measurements in Middle Side Channel 8A. .......................................................................... 40
Figure 4.1-17. Cross-section diagram showing Upper Aquatic Transect on Slough 8A, with
groundwater stations ESGFA128-7, ESGFA128-18, and ESGFA128-19. Wells are shown
and water levels and channel water level for April 22, 2014. ............................................... 40
Figure 4.1-18. Groundwater Station ESGFA128-7 groundwater levels in wells adjacent to
Slough 8A and surface-water stage in Slough 8A, and groundwater levels from wells at
ESGFA128-18 and ESGFA128-19. ...................................................................................... 41
Figure 4.1-19. Groundwater Station ESGFA128-7 groundwater temperature in wells adjacent to
Slough 8A and surface-water temperature in Slough 8A, and groundwater temperature from
wells at ESGFA128-18 and ESGFA128-19. ........................................................................ 41
Figure 4.1-20. Groundwater Station ESGFA128-7 select streambed temperature profile
measurements in Slough 8A. ................................................................................................ 42
Figure 4.1-21. Groundwater Station ESGFA128-6 groundwater levels in wells adjacent to
Slough 8A and surface-water stage in Slough 8A, and groundwater levels from wells at
ESGFA128-18 and ESGFA128-19. ...................................................................................... 42
Figure 4.1-22. Groundwater Station ESGFA128-6 groundwater temperature in wells adjacent to
Slough 8A and surface-water temperature in Slough 8A, and groundwater temperature from
wells at ESGFA128-18 and ESGFA128-19. ........................................................................ 43
Figure 4.1-23. Groundwater Station ESGFA138-1 groundwater levels in wells adjacent to
Slough 11 and surface-water stage in Slough 11. ................................................................. 43
Figure 4.1-24. Groundwater Station ESGFA138-1 groundwater temperature in wells adjacent to
Slough 11 and surface-water temperature in Slough 11. ...................................................... 44
Figure 4.1-25. Groundwater Station ESGFA138-2 groundwater levels in wells adjacent to
Slough 11 and surface-water stage in Slough 11. ................................................................. 44
Figure 4.1-26. Groundwater Station ESGFA138-2 groundwater temperature in wells adjacent to
Slough 11 and surface-water temperature in Slough 11. ...................................................... 45
Figure 4.2-27. Susitna River at Gold Creek (USGS 1529200) discharge compared with Middle
Side Channel 8A stage conditions on the Lower Aquatic Transect in FA-128 (Slough 8A) at
ESGFA128-13. Selected data are from summer (ice-free) conditions. ............................... 45
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 4.2-28. Susitna River at Gold Creek (USGS 1529200) discharge compared with Slough
8A stage conditions above confluence with the Middle Side Channel 8A and the Lower
Aquatic Transect in FA-128 (Slough 8A) at ESSFA128-1. Selected data are from summer
(ice-free) conditions. ............................................................................................................. 46
Figure 4.2-29. Susitna River at Gold Creek (USGS 1529200) discharge compared with Slough
8A adjacent groundwater conditions at the Upper Aquatic Transect in FA-128 (Slough 8A)
at ESGFA128-18. Selected data are from summer (ice-free) conditions. ........................... 46
Figure 4.2-30. Analysis example for the response between flow conditions at Susitna River at
Gold Creek and the Middle Side Channel 8A located at the Lower Aquatic Transect in FA-
128 (Slough 8A). The example demonstrates the relationship of stage data for summer (ice
free conditions). .................................................................................................................... 47
Figure 4.2-31. Analysis example for the response between flow conditions at Susitna River at
Gold Creek and the Upper Side Channel 11 located at the Upper Aquatic Transect in FA-
138 (Slough 11). The example demonstrates the relationship of stage data for summer (ice
free conditions). .................................................................................................................... 47
Figure 4.3-32. Downwelling example in Middle Side Channel 8A in FA-128 (Slough 8A)
showing groundwater and surface-water levels, stream-bed temperatures, and thermal
profile of the stream bed conditions through the major hydrologic periods. ........................ 48
Figure 4.3-33. Upwelling example in Upper Side Channel 11 in FA-138 (Gold Creek) showing
groundwater and surface-water levels, stream-bed temperatures, and thermal profile of the
stream bed conditions through the major hydrologic periods. .............................................. 49
Figure 5.0-34. Conceptual model of groundwater-surface water interactions and the thermal
regime occurring under high stage and low stage conditions within lateral habitats of the
Susitna River. ........................................................................................................................ 50
APPENDICES
Appendix A. Hydrologic Stations Primary Station Purpose, Location and Data Collection
Parameters
Appendix B. April 2014 Discharge Measurements
Appendix C. 2014 Groundwater Study Response Analysis Time-lapse Image Data at Site
ESSFA128-1
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
LIST OF ACRONYMS AND SCIENTIFIC LABELS
Abbreviation Definition
AEA Alaska Energy Authority
°C Degrees centigrade
Cfs Cubic feet per second
Cm Centimeter
FA Focus Area
FERC Federal Energy Regulatory Commission
Fps Feet per second
GW Groundwater Study
GW/SW Groundwater/Surface Water
GWS Geo-Watersheds Scientific
LB Left Bank
mg/L Milligrams per liter
Mw Megawatts
NTU Nephelometric Turbidity Units
IFS Instream Flow Study
ISR Initial Study Report
PRM Project River Mile
NAVD88 North American Vertical Datum of 1988
RB Right Bank
RSP Revised Study Plan
RPD Riparian Process Domain
TM Technical Memorandum
WSE Water Surface Elevation
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vi September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
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. 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 aquatic and
riparian resources and processes related to groundwater conditions and groundwater surface
water conditions. As a result, AEA developed and the FERC approved (FERC 2013) a detailed
Groundwater Study (GW) plan (contained as Section 7.5 in the December 14, 2012 Revised
Study Plan [RSP]; see AEA 2012) containing nine specific tasks that were collectively designed
to evaluate the potential effects of Project operations on groundwater resources.
Task 6 of the GW plan centers on defining groundwater/surface water (GW/SW) relationships
associated with upwelling/downwelling areas in relation to spawning, incubation, and rearing
habitats within selected Focus Areas 1. This task is linked with the Fish and Aquatics Instream
Flow Study (FA-(IFS) (RSP 8.5) with one of the objectives being the development of GW/SW
response functions for different locations within a FA that can be used to assess potential
changes in GW/SW interactions resulting from different Project operational scenarios. These
relationships will provide estimates of groundwater flow that will be integrated into the SRH-2D
models (Tetra Tech 2014) and the habitat-flow models and used to evaluate how spawning and
1 Focus Areas are specific geographic areas within the Middle Segment of the Susitna River that were selected to be intensively
evaluated across multiple resource disciplines (RSP 8.5.4.2.1.2) There are ten Focus Areas located in the Middle Segment of the
river (see R2 Resource Consultants 2013). The Task 6 GW investigations were concerned with seven of the FAs including FA-
104 (Whiskers Slough), FA-113 (Oxbow 1), FA-115 (Slough 6A), FA-128 (Slough 8A), FA-138 (Gold Creek), FA-141 (Indian
River), and FA-144 – (Slough 21), with studies concentrated in FA-104, FA-128 and FA-138.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
incubation habitats (as influenced by GW flows) change as a result of Project Operations.
Furthermore, the GW analysis completed within the FAs will provide a better understanding of
how GW/SW relationships operate more broadly and will be used to draw inferences regarding
Project operational effects at other locations within the Middle Segment of the river.
This Technical Memorandum (TM) provides an overview of the types of data and information
that are being collected to support the Task 6 GW/SW activities, and describes the methods and
techniques that are being applied in analyzing the data leading to development of response
functions to be used for evaluating Project operational effects. The TM centers on the analysis
for FA-128 (Slough 8A) and to a lesser extent FA-138 (Gold Creek) and represents an expansion
of the presentation materials provided during the Proof of Concept (POC) meetings held on April
15-17, 2014. During those meetings, information concerning the locations and methods for data
collection were presented, as well as preliminary data plots illustrating trends in groundwater
levels and water temperatures over time and in relation to mainstem discharge. However, details
concerning data analysis techniques and response function development were not presented, and
hence are included as part of this TM. An important qualifier of this TM is that although site
specific data have been used, the data analysis techniques and the results presented herein are all
subject to revision as additional data are collected and alternative analytical techniques are
employed.
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. Importance of Groundwater to Fish Habitat in the Susitna River
Many studies have shown the proclivity of salmonid species to utilize areas of groundwater
upwelling for spawning and egg incubation. Durst (2000) summarized some of the more recent
studies on this with a focus on Alaska rivers and pointed out the obvious survival benefits of
groundwater upwelling as providing warmer winter temperatures to prevent freezing of eggs and
promote embryogenesis, and sustained or increased intergravel flows that transport needed
dissolved oxygen to and metabolic wastes from the developing embryos. Studies have
documented groundwater use by kokanee salmon (Oncorhynchus nerka) (Garrett et al. 1998),
chum salmon (Barton 1992, Kogl 1965, Geist et al. 2002) and sockeye salmon (Lorenz and Eiler
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
1989), as well as several char species including bull trout (Salvenline malma) (Baxter and
McPhail 1999; Baxter and Hauer 2000) and brook trout (S. fontinalis) (Blanchfield and
Ridgeway 1997; Benson 1953).Durst (2000) suggested that in a general sense, the importance of
upwelling areas to maintenance of healthy fish populations has not been fully appreciated by
fisheries and land managers. For example, in the Tanana River, Barton (1992) noted that the
relatively numerous and small spawning areas in the main stem of the river cumulatively
contribute significantly to the total available spawning area for Tanana Basin fall chum salmon.
Garrett et al. (1998) concurred on the importance of upwelling areas to fish and suggested that
managers consider affording special consideration to such areas.
Special consideration of groundwater upwelling as being an important component of fish habitat
was given as part of the 1980s studies of the Su-Hydro Project. As noted in R2’s (2013a)
review of the 1980s data, the importance of groundwater to fish and fish habitat in the Susitna
River was first identified during studies when spawning salmon were observed to be associated
with areas of groundwater upwelling. Trihey (1982) evaluated 13 of those areas and found that
intergravel temperatures at those locations were higher and more stable than surface
temperatures. Differences in intergravel dissolved oxygen concentrations were found between
areas of groundwater upwelling and adjoining areas of surface flow, with concentrations
generally lower in the upwelling areas.
Vining et al. (1985) suggested that upwelling was the single most important feature in
maintaining the integrity of incubation in slough habitats of the Susitna River as well as localized
areas in side channel habitats. The importance of groundwater on fish habitat was noted as being
especially important during the winter time owing to its’ warming effects and benefits associated
with temperature constancy and egg development and survival. Vining et al. (1985) found that
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). Freezing and desiccation were the two primary sources of embryo mortality
associated with the non-groundwater influenced areas. In addition to the importance to
incubating salmon eggs, groundwater inflows to sloughs were also considered important as
overwintering habitat (Dugan et al. 1984) that provided warmer water temperatures resulting in
areas that were ice-free. Specific groundwater upwelling locations were mapped at a number of
survey locations in the Middle and Lower River as part of the 1980s studies; Estes and Schmidt
(1983, Appendix F) reported the location of approximately 90 upwelling sites in the Middle
River.
Efforts to define GW/SW relationships were likewise completed during the 1980s studies with
emphasis placed on selected slough habitats (Slough 8A, Slough 9, and Slough 11)2 where
salmon had been observed spawning (R&M 1985; Beaver 1984). Those studies highlighted
differences in discharge and temperature relationships that are inherent between the different
slough locations. The results of those studies were used in part to make an informed evaluation
of potential Su-Hydro Project effects on groundwater conditions (Entrix 1986), as well as to
2 Slough 8A is contained within Focus Area FA-128; Slough 11 is contained within Focus Area-138. Slough 9 is outside of the
defined Focus Areas.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
identify potential mitigation options for protecting or replacing important habitats influenced by
groundwater (Woodward Clyde 1984).
1.2.2. Susitna-Watana Project Groundwater Studies
The current Susitna-Watana GW studies associated with Task 6 (Study 7.5, Section 7.5.4.5) have
been built around the solid base of information concerning the importance of groundwater
upwelling on fish habitats provided by the 1980s studies. The study elements have been closely
coordinated with the IFS-FA program (Study 8.5) including the winter studies (R2 2013b; R2
2014a, b), the IFS-Riparian program (Stud y 8.6) and other resource studies associated with Ice
Processes (Study 7.6), Water Quality (Study), and Fluvial Geomorphology (Study 6.6), and are
designed to provide a set of analytical tools that can be used to evaluate potential Project
operational effects on groundwater flows and associated fish habitats.
Task 6 is especially interested in determining the potential effects Project operations may have
on groundwater flows associated with important fish habitats. Such effects will likely vary
spatially, seasonally and will be highly dependent on specific Project operational characteristics.
In a general sense, the types of groundwater related response functions that may occur as a result
of Project induced increases and/or decreases in discharge and stage include:
• Decreases or increases in the rate of groundwater upwelling from the adjacent
floodplain.
• Modifications in the amounts of relatively warm, stable, upwelling habitat when side
channels are breached or disconnected by mainstem flow.
• Changes in the rate of groundwater flows associated with hydraulic gradients between
main channel and off-channel habitats.
1.3. Technical Memorandum Objectives
The objectives of this TM are to report the general data collection activities that were completed
in 2014 to support Task 6 activities, present examples of data analysis using FA-128 (Slough 8A)
as a primary example and FA-138 (Gold Creek) secondarily, and describe plans for data
collection in 2015. The TM covers study objectives specific to the IFS-FA evaluations and how
they relate to groundwater and surface water (GW/SW) interactions. Select examples from FA-
138 (Gold Creek) are also shown and discussed to demonstrate the analysis approaches over a
greater range of lateral-habitat hydrologic conditions.
2. STUDY AREA
As established by RSP Section 7.5.3, the overall study area related to groundwater processes
includes primarily the Middle River Segment of the Susitna River that extends from PRM 102.4
to PRM 187.1 as well as portions of the Lower River Segment associated with domestic wells
and riparian transect locations in the Lower River, and the lower most portion of the Upper River
Segment near the proposed dam site associated with potential groundwater changes relative to
reservoir construction and operations. Figure 2.0-1 shows these river segments and the general
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watershed boundary of the Susitna River. Figure 2.0-2 shows the location of Instream Flow
Study (Section 8.5, 8.6) Focus Areas and geomorphic reaches for the Middle River Segment.
This TM is concerned with two of the Focus Areas in the Middle River Segment, FA-128
(Slough 8A) (Figure 2.0-3 through Figure 2.0-6) and FA-138 (Gold Creek) (Figure 2.0-7 through
Figure 2.0-9).
3. METHODS
As noted above, the overall goal of this study component is to collect information and data to
analyze and define GW/SW interactions and processes at a number of Focus Area locations
important for aquatic resource evaluations, with this TM centered on FA-128 (Slough 8A) and to
a lesser extent FA-138 (Gold Creek) (see ISR 7.5.5.6 for specific methods employed at all Focus
Areas). Focus Area results will ultimately be used to extrapolate effects to other aquatic habitats
at the river segment scale. The methods employed as part of the analysis are described below
and include field efforts to collect water surface elevation and discharge data, as well as
collection of stationary and aerial imagery to allow visual assessments of surface flow
(evidenced by turbid water) and groundwater (clear water) interactions. Methods are also
presented that describe the types of data analysis that were used to evaluate data collected in FA-
128 and FA-138 and define various GW/SW relationships both in terms of stage, flow and water
temperature.
Ultimately, various hydraulic and physical models, including surface water hydraulic (1-D and 2-
D), geomorphic reach analyses, and ice processes will be integrated as needed to allow
assessment of physical process controls of select habitat assessed (see Study 8.5) under both
existing conditions and Project operational scenarios. The results of the GW study will be used
to draw appropriate inferences on GW/SW processes at the river segment and geomorphologic
scale.
As described in the Initial Study Report (ISR), empirical data are being collected at five Focus
Areas (FA-104 (Whiskers Slough), FA-113 (Oxbow 1); FA-115 (Slough 6A), FA-128 (Slough
8A); and FA-138 (Gold Creek) to define GW/SW interactions relative to the IFS-FA studies (see
ISR 7.5, Figures 4.5-2, 4.5-3, 4.5-5, and 4.5-6). The data collection stations established within
each Focus Area serve multiple study needs with some of the stations collecting measurements
of groundwater level and water quality (temperature and conductivity), some stations collecting
measurements of surface water levels, discharge and water quality, and some fixed stations
collecting time lapse photographs to document flow condition changes over time (see Figure 4.5-
1 of ISR 7.5 for station naming conventions).
3.1. Hydrology Observations
3.1.1. Water Surface Elevations and Water Temperature Measurements
Water surface elevations are being measured at both groundwater and surface-water stations
within each of the Focus Areas as listed in ISR 7.5 Table 1 through Table 8 and shown in ISR
7.5 Figures 4.5-12 through 4.5-24. The stations for FA-128 and FA-138 are shown in Figure 2.0-
3 through Figure 2.0-9) and include 23 groundwater measurement locations and 17 surface-water
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measurement locations in FA-128, and 7 and 10 locations respectively for FA-138. These
measurements are intended to provide data at the different stations including those associated
with specific transects for analysis of GW/SW interactions taking place over the range of
hydrologic conditions from summer through fall freeze-up, winter, and spring snowmelt and
breakup.
At stations with pressure transducers (PTs), manual water level measurements were made to help
process the continuous data and apply data shifts and corrections as needed due to potential
movement of the PT. The PTs used for the study also record water temperature at the location of
the sensor. In addition, intergravel water temperature profiles were measured via placement of
thermistor strings that recorded temperatures at different depths within the substrate. Depending
on the complexity of the hydrologic station, PTs are either part of the overall sensors measured
by Campbell Scientific Inc. CR1000 or CR200X data loggers, or are self-logging pressure
transducers at groundwater and surface-water stations where fewer measurements are required.
Manual water level measurement in surface-water stations are frequently made by level-loop
surveying. Level-loop surveys are performed with optical survey levels and measurement goals
for level loop closures are 0.02 ft. There are three to four reference elevation benchmarks to use
for summer and winter surveying at a majority of the stations. These benchmarks have had at
least one measurement point surveyed by RTK survey methods to establish sea level datum at
each station.
All groundwater wells including those installed in FA-128 and FA-138 were installed by drive
point methods with pre-drilling to help installation. The wells all have the top of galvanized
casing protected by enclosures that have survey measurement control marks on them. These
measurement locations are surveyed by level loop survey methods and used as a reference point
to measure the depth to groundwater in the well.
In 2014, 42 staff gages were installed in various Focus Areas and other locations in a combined
effort between GW Task 5 (IFS-Riparian) and GW Task 6 (IFS-FA) to provide various study
crews the ability to take water level readings at these locations. FA-128 had 8 staff gages
installed, and FA-138 had 8 gages installed. This same approach was successfully used in the
1980s Susitna studies. These locations are all in lateral side channels, sloughs and beaver ponds
where they require less maintenance during the summer ice free hydrologic period.
Listings of all groundwater and surface-water stations used in the GW study are provided in
Appendix A, Table 1 through Table 8 which are organized by Focus Area or PRM. The station
information tables include both stations and sensors installed in 2013 and in new data collection
sites established in August 2014. One non-Focus Area location is included at PRM 112 (Slough
6).
3.1.2. Discharge Measurements
Winter discharge measurements were taken during two periods, March 3-16, 2014 and April 1-
13, 2014 at selected locations in FA-104 (Whiskers Slough), FA-128 (Slough 8A) and FA-138
(Gold Creek). Measurements were recorded in open water and ice covered areas within side
channel, side slough and upland slough habitats. Discharge was measured at eight locations in
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FA-104 (Whiskers Slough), five locations in FA-128 (Slough 8A) and at six sites in FA-138
(Gold Creek) (Table 3.1-1). Measurement locations were established in habitats with substantial
groundwater influence and known fish habitat use during winter.
An additional series of end-of-winter discharge measurements to document groundwater
recharge or discharge in surface water features were made from April 16-26, 2014 in the same
three Focus Areas noted above. Table 3.1-2 shows a summary of the discharge measurement
results; detailed computational sheets for each discharge measurement are contained in Appendix
B. For these measurements, channel sections were chosen that had no or minimal ice and snow
conditions, so an open channel measurement could be made. Paired measurements were made in
select areas to measure the difference in discharge for certain channel reaches. In some
locations, the characteristics of the slough or side channels did not allow this and individual
locations were measured. Because the goal of these measurements was to measure small
differences in groundwater for groundwater recharge to the sloughs or side channels, triplicate
measurements were made at some locations when field logistics allowed.
The discharge measurements were made following the USGS procedures reported in Turnipseed
and Sauer, 2010. Water velocities were measured with a USGS Type Price AA mechanical
discharge meter with magnetic head or USGS Type Pygmy discharge meter with magnetic head,
either of which is attached to a wading rod. The Price AA meter was used if the depths were
greater than 1.0 feet. If the depths were between 0.3 and 1.0 feet, the Pygmy meter was used. If
depths are less than 0.3 feet, the discharge in the segment was not measured. An AquaCalc Pro
Plus electronic notebook was used to connect to the meter at the top of the wading rod and
collect all meter data and make calculations of the velocity, discharge and other calculations.
A series of late summer discharge measurements were likewise collected in FA-128 (Slough 8A)
during the week of September 22-26, 2014. These locations have been established in 2014 to
collect discharge measurements for development of rating curves to develop estimates of
discharge from stage data collected at many of the surface water stations. The location of
discharge measurements are also shown in the Focus Area data collection parameters
information presented in Appendix A, Table 1 through Table 8.
3.1.3. Land-based and Aerial Photographic Imagery
Visual documentation of water levels and other hydrologic features is available at the Focus
Areas via a series of land-based stationary time lapse cameras (see Figure 2.0-3 through Figure
2.0-9 for locations in FA-128 and FA-138). Photographs from these cameras can be used in part
to help document the distribution of flows within a Focus Area over time, and the connectivity of
specific channels to mainstem flows, as evidenced by the presence or absence of turbid water
(see Appendix C for example of time lapse photographs taken from FA-128 (Slough 8A) at site
ESSFA128-1 under different flow conditions).
In addition, aerial surveys were completed during a number of the field efforts to photo
document conditions in all the surface-water sloughs and side channels, beaver ponds and other
hydrologic features in each Focus Area. These empirical photographic data sets help document
ice and snow cover conditions during winter conditions, changes in channel conditions, changing
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beaver dam and channel changing activities, and the general characteristics of the surface-water
features in each Focus Area.
3.2. Analysis Methods
The below sections describe general data collection and preliminary data analysis methods used
in this TM. The analysis considered four main periods where hydrologic conditions and related
GW/SW interactions may vary. These periods are defined as Fall Freeze Up, Winter (ice cover),
Spring Break-Up, and Summer (ice free) and are depicted in Figure 3.2-10, which also shows the
period of record daily mean flow statistics for the Susitna River at Gold Creek USGS gaging
station (15292000) (USGS, 2014). Using these seasons to help describe GW/SW interactions is
important as the hydrologic processes and boundary conditions change over the seasons, as does
fish species and life stage periodicity.
3.2.1. Empirical Analysis Methods
As an initial step in the FA-128 and FA-138 analysis, water level and temperature data were
plotted together in various combinations to examine relationships between groundwater
conditions and adjacent surface water features. Time series plots were then used at different time
scales to show response changes between GW/SW systems. The primary information used to
study these interactions is water levels as relative pressure (water height) gradients are the
foremost process driving interactions. Temperature data were also used as indicators of GW/SW
mass interaction, since temperatures differ between groundwater and surface water. Manual
discharge measurements in channels were used to measure groundwater recharge to surface
water bodies (upwelling or gaining stream reaches) or discharge from surface water to
groundwater (downwelling or losing stream reaches).
For the GW Study, the study design consisted of a transect with two wells on either side of the
surface-water feature of interest (slough, side channel). Water elevations in the surface water
feature and each groundwater location across the transect were used to develop a 2-D cross
section view of GW/SW interactions. By comparing the difference between groundwater and
surface water levels across the transect, hydraulic gradients or water table slopes can be
calculated from aquifer positions to determine the horizontal and vertical flow direction, and the
extent of GW upwelling or SW downwelling between surface water and adjacent aquifers.
Empirical data comparisons between different types of lateral aquatic habitats and hydrologic
conditions were used to understand and characterize the range of GW/SW interactions taking
place across Focus Areas.
3.2.2. Functional Relationships with Susitna River Flow
A primary objective of this TM is to show analytical approaches and examples of the
relationships between Susitna River flow conditions and lateral aquatic habitat areas that are
influenced by groundwater conditions. The flow conditions for the Susitna River were taken
from the Susitna River at Gold Creek gage location for 2013 and 2014 (Figure 3.2-11 and Figure
3.2-12). Discharge data (15 minute) were used to compare with stage conditions at aquatic
transect and other hydrology stations and associated groundwater wells. Temperature data from
these same sites were also used to understand the hydrologic conditions at each site.
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Pairs of Susitna River at Gold Creek discharge and lateral aquatic habitat water level conditions
were then chosen for analysis. FA-128 (Slough 8A) was used for the primary development of
the analysis method, with additional stations used from the two aquatic stations in FA-138 (Gold
Creek) to help provide further examples of the analysis methods.
As part of this analysis, the lateral habitat areas were first divided into three main hydrologic
categories to help establish relationships that could be transferred to other lateral aquatic habitat
areas outside of the Focus Areas. These categories are defined as;
• Riverine Hydrology Dominated
o Flow, stage, and water quality conditions in lateral habitats are predominantly
influenced by mainstem flow, stage, and water quality conditions.
• Transitional Hydrology Dominated
o Due to seasonal and event related flow conditions, the flow, stage and water
quality conditions in lateral habitats vary between riverine and upland dominated
sources of flow.
• Upland (or Hillslope) Dominated
o Flow, stage and water quality conditions in lateral habitats are predominantly
influenced by sources of groundwater and surface water that originate in upland
areas.
All of the above hydrologic classifications are impacted by groundwater, but the degree and
characteristics of river effects on GW/SW interactions varies. The above classifications fit into
the concept of hydrologic landscapes (Winter, 2001).
Once empirical data were QA/QC checked they were plotted and specific flow intervals used for
the analysis. For this, data were primarily used from rising and falling limbs on the discharge
hydrographs of the Gold Creek gage. Peaks that represented single snowmelt (upper basin) or
precipitation events were chosen and compared with hourly data selected from within a greater
range of conditions. After visually inspecting data, portions of the data sets were then analyzed
with a statistical program TableCurve 2D (SYSTAT, 2002), to define linear relationships for the
flows of interest at each site.
3.2.3. Groundwater Modeling
In addition to the analysis of empirical data that are presented in this TM, 2-dimensional (2D)
cross-sectional groundwater models are being developed for each of the aquatic transects in FA-
138 (Gold Creek), FA-128 (Slough 8A), and FA-104 (Whiskers Slough). These models will
provide a better understanding of GW/SW interactions and how they vary across different types
of lateral aquatic habitats under natural flow conditions. In addition to the 2D modeling efforts,
FA-128 (Slough 8A) was selected for development of a 3-dimensional (3D) model for use in the
Task 5 IFS-Riparian studies and for comparative purposes with the 2D models.
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For this, the USGS modeling package MODFLOW (Feinstein et al. 2012; Maddock et al. 2012;
USGS 2005) was selected for use based on guidance in ASTM D6170 “Standard Guide for
Selecting a Groundwater Modeling Code” (ASTM, 2010). ASTM standard D5981 is being used
to help develop calibration goals and procedures for groundwater modeling efforts (ASTM
2008).
To date, elevation surveying has been completed at each transect to provide the upper land
surface boundary and location of monitoring wells and other empirical observation points.
Methods for integrating input data from the 1-dimensional (1D) HEC-RAS model (summer, ice-
free) (ISR 8.5; Appendix K (R2 2014c)) are under development. The 2D hydraulic models will
be used to develop synthetic stage-discharge relationships at the groundwater modeling transects
for specific flow conditions simulated by the 2D hydraulic models. During fall freeze-up,
winter, and spring breakup, output from the Ice Processes Study River1D model will be used for
future stage input.
3.3. Deviations from Study Plan
The GW study methods were implemented as described in the Study Plan with only some
variances in schedule for tasks not related to field activities (see ISR Study 7.5, Section 4.5).
4. RESULTS
4.1. Hydrology Observations
Hydrologic observations of GW/SW interactions and related data have been made in FA-128
(Slough 8A) since late summer 2013 and have covered the four primary seasons for the annual
hydrologic year (Figure 3.2-10). One Station (ESSFA128-1) (Figure 2.0-5) was established as
part of the 2012/13 winter studies conducted by IFS 8.5, FDA 9.6 and GW 7.5 and measured
end-of-winter 2013 conditions as well as spring snow and breakup in 2013. The 2013/14 winter
season was intensely monitored by the network of groundwater and surface water stations in FA-
128 (Slough 8A), FA-138 (Gold Creek) and other relevant Focus Areas. The hydrology
conditions observed during the winter of 2013/14 were substantially different in FA-128 (Slough
8A) and FA-138 (Gold Creek) with both Focus Areas experiencing lateral habitat flooding by
mid-winter ice jams in the 2013/14 winter that did not occur in the 2012/13 winter. During the
April late-winter field trip 2014 surface discharge was measured to characterize groundwater
recharge (upwelling) to select lateral habitats (Table 3.1-2).
An early snowmelt and breakup period was measured in late April and early May. This was
followed by a period of lower water level conditions in late May and early June with typical
summer precipitation stage events in June through August. Additional water level, discharge and
water quality data were collected in September 2014 to help characterize the end of the summer
2014 hydrologic period.
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4.1.1. FA-128 (Slough 8A)
The hydrology data collected in FA-128 (Slough 8A) in 2013 and 2014 covered a broad range of
hydrologic conditions. Figure 2.0-3 shows the general location of FA-128 (Slough 8A) and Inset
B (Figure 2.0-5) shows the location of the lower aquatic transect at ESGFA128-13 (Figure 4.1-
13), which is downstream of the confluence between Slough 8A and Middle Side Channel 8A.
The cross-section profile for this transect shown in Figure 4.1-13 is oriented with the viewer
looking downstream. ESGFA128-13 is located on the Left Bank (LB) side of the channel and
ESGFA128-20 is located on the right
Groundwater station ESGFA128-21 is located at the far end of the Right Bank (RB) side of the
channel to help measure the groundwater slope along the transect from the direction of the
Susitna River. The GW/SW conditions are not symmetrical between the LB and RB sides of the
channel. Figure 4.1-14 shows the groundwater levels and surface-water stage for all stations in
this transect. Groundwater and surface-water levels generally follow similar patterns, though
there are various periods were the gradients are reversed. Multiple events occurred at the end of
2013 where breaching flows entered Middle Side Channel 8A resulting in increased water levels
at the study reach. The late precipitation events in October 2013 were precipitation stage
changes. Low water conditions were measured in November and December 2013. This is the
time period where water levels may be lowest, before fall ice jams and winter ice development
results in increased stage levels.
Mid-Winter ice jams in the main stem created beaching stage (not flow) conditions that resulted
in mid-winter flooding of Middle Side Channel 8A in January 2014, first with a small event,
followed by the peak event for the winter period in the middle of January. Surface water
conditions rose over adjacent groundwater conditions, reversing the hydraulic gradients during
this period. Both groundwater and surface-water levels were higher during the middle of winter
than during the summer high-water season in 2014, with the exception of spring snowmelt and
break-up flooding that occurred in early May 2014. Following the spring snowmelt and break-
up period, water levels in the channel and adjacent groundwater dropped to low levels. During
the summer of 2014, water levels increased starting in mid-June and continued to increase with
varying stage conditions in July, dropping back to lower water levels with minor precipitation
peaks.
The groundwater and surface water temperature data for the period of record is shown in Figure
4.1-15. The surface water temperature is affected by breaching flows from the mainstem Susitna
River and reached water temperatures a little over 16ºC in August of 2013. The summer
conditions in 2014 were cooler with temperatures only reaching about 12ºC in July. The surface-
water temperatures dropped rapidly as the summer period ended in 2013 and conditions
transitioned into the early winter freeze-up period. The breaching winter stage conditions in
January kept surface-water temperatures near 0ºC for the rest of the winter period in 2014. In
general groundwater temperatures were highest at ESGFA128-21, which also has higher
groundwater levels. The two wells on the LB side of the channel indicate colder surface-water is
discharging (downwelling) to groundwater on this side of the channel. Warmer groundwater
conditions in ESGFA128-20 coincide with higher groundwater levels compared with the side
channel, indicating warmer groundwater is coming into the channel on the RB side. The
streambed temperature profile string at this section (Figure 4.1-16) indicates that during winter
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conditions, this is a discharge section (stream reach) to groundwater, with temperatures in the
stream bed to 100 cm close to 0ºC for most of the winter period.
The upper aquatic transect is located near the center of Slough 8A at the ESGFA128-7 station
(Figure 2.0-5). This station has different hydrology characteristics compared to the lower
aquatic transect in Middle Side Channel 8A. The cross-sectional profile for this channel is
shown in Figure 4.1-17. There are two groundwater wells on the RB side of the slough and two
groundwater wells on the LB side. Slough water level, temperature and streambed temperature
profiles are measured by the ESGFA128-7 station. The groundwater and surface-water levels for
this section are shown in Figure 4.1-18. Surface-water stage varies less than in the lower Middle
Side Channel 8A. This portion of Slough 8A is above any backwater influences from the side
channel. Breaching flows from the Susitna River occur at higher flow conditions and were
measured in August and September of 2013. Local precipitation had a minor influence on water
levels in October of 2013, and subsequently water level conditions in the slough were fairly
constant until breaching stage conditions due to ice in the main channel flooded Slough 8A in
mid-January and again in mid-February. Between these two events, there were likely
overtopping stage conditions at the upper end of Slough 8A. After these winter events, the stage
conditions in Slough 8A returned to a steady condition, only slightly higher than the water level
conditions before winter flooding occurred. The spring snowmelt and ice jam flooding from the
Susitna River created breaching flow and stage conditions in early May for a brief period.
Following the flooding event, water levels were variable, due to snowmelt runoff into the slough.
Data from the summer period is inferred from the adjacent wells (ESGFA128-18, ESGFA128-
19) as the spring breakup flooding and the resulting ice damage tore out the surface-water
pressure transducer and damaged the well closest to the slough on the RB (ESGFA128-7 W1),
along with the streambed temperature profile sensor from this site.
The groundwater and surface-water period of record water temperature for the upper aquatic
section is shown in Figure 4.1-19. The groundwater temperatures on both sides of the slough are
generally warmer than the surface water in the slough for most of the winter. With increasing
day light in March the slough water temperatures start increasing and showing diurnal
temperature variation with steadily increasing temperatures through the beginning of May, when
spring breakup and ice jam flooding tore out the sensors in the slough. The small channel on the
RB side of the Slough (Figure 4.1-17) has an impact on groundwater temperatures that recharge
the slough from the right bank side. This is seen during February 2014 when ice jam breaching
stage conditions resulted in flooding of this channel and a rapid drop in groundwater
temperatures in ESGFA128-7 W2 during the flow due to the flooding of cold main channel
water coming down the slough (Figure 4.1-18). The streambed temperature conditions also
reflect the reversals in groundwater gradients in January 2014 for a brief time and later in
February 2014 for more than a week (Figure 4.1-20). The stream bed conditions indicate
groundwater upwelling in this section, except for the transient conditions during flooding. The
temperature profile sensor string was pulled out by spring breakup flooding and reinstalled in
late August 2014.
An additional station located upstream of the upper aquatic transect is ESGFA128-6, which is at
the end of the upper Riparian Transect. This station records surface-water stage in Slough 8A,
just upstream of a small beaver dam (approximate height is about 1.5 feet) and an adjacent
groundwater well to the slough. Groundwater and surface water levels are shown in Figure 4.1-
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21 and water temperature in Figure 4.1-22. The site is located on the RB side of the slough and
is influenced by surface water stage changes in the main channel. This results in the gradient
between groundwater and the slough to be increasing during the early winter months when ice
jams are forming and increasing stage levels are occurring in the main channel and late winter
decreasing gradients as stages drop in the main channel. During this time the slough levels are
relatively stable except when overtopping stage conditions are flooding the slough, as seen
briefly in January and more notably in February 2014. Water temperature differences between
groundwater and the slough show groundwater conditions to be warmer through the winter until
solar heating of the slough surface water starts to increase in March and becomes warmer than
adjacent groundwater in early April 2014. During the summer months, groundwater
temperatures are steadily rising but cooler than the surface water in the slough.
Winter discharge measurements were made in April 21, 2014 at two locations on Slough 8A at
the same stage conditions to measure the difference in flow. Table 3.1-1 shows the summary
information for discharge measurements presented in Appendix B. The average discharge
measured at the upstream end of the slough at location S8AX2US was 0.76 cubic feet per second
(cfs). The downstream location was just below the upper aquatic transect at S8AX2DS and the
average measured flow was 6.04 cfs. The difference in flow, or recharge to the slough from
groundwater along this reach of Slough 8A was 5.28 cfs. The amount of recharge to the slough
will vary with GW/SW gradients, which are being measured in the aquatic transects and
interpreted from the other data collection stations in the Focus Area.
4.1.2. FA-138 (Gold Creek)
Select data are presented for FA-138 (Gold Creek) to enable comparisons in groundwater and
surface water responses between Slough 11 and Upper Side Channel 11 (in FA-138) and Slough
8A and Middle Side Channel 8A (in FA-128).
Water levels in Slough 11 and adjacent wells on the RB are shown in Figure 4.1-23. Only one
breaching event in December 2011 impacted Slough 11 during the study period as a response to
river freeze-up and early winter ice jams in the main channel. The groundwater relationships
with water levels in the slough vary over the hydrologic seasons, but in general the slough acts as
a drain and is lower than adjacent groundwater conditions except for the overtopping winter
stage conditions and some variation during winter related to ice formation in the channel with
variations in air temperature. The water temperature varies slightly at this location from a low
temperature just above 2ºC and highs near 5ºC (Figure 4.1-24). The warmer groundwater
recharging the slough (upwelling) helps keep open water conditions in the slough for most of the
winter period.
Water level and temperature measurements for Upper Side Channel 11 and adjacent wells
located at ESGFA138-2 are depicted in Figure 4.1-25 and Figure 4.1-26, respectively. In
general, water levels at this lateral habitat area illustrate a strong relationship to stage conditions
in the main channel of the Susitna River (Figure 4.1-25). During early winter ice-jam flooding
of Upper Side Channel 11, water level increased rapidly and varied throughout January and
February 2014. A steady recession in water level condition occurred in the groundwater wells
until the winter low period in mid-April. The surface water pressure transducer was damaged by
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ice in late January 2014 and replaced in late June 2014. Groundwater temperature trends follow
similar patterns to those wells in Slough 11 (Figure 4.1-26).
4.2. Functional Relationships of Surface and Groundwater Levels to
Susitna River Flow
The analysis of hydrologic data for FA-128 (Slough 8A) and FA-138 (Gold Creek) indicate that
the response of groundwater levels to mainstem stage and flows in the Susitna River varies over
space and hydrologic time period negating the ability to define a single uniform response
function applicable to all areas. This was likewise noted during the 1980s studies of both Slough
8A and Slough 11 (R&M 1985). As part of the exploratory analysis of these relationships, the
hydrology data previously discussed was used with flow data from the Susitna River at Gold
Creek USGS gage record (USGS 2014) to evaluate how lateral habitats may respond to changes
in flow and stage in the Susitna River. For this TM, the analysis was limited to the open-water
periods of the hydrograph, but ultimately both open-water and ice-covered periods will be
evaluated.
There are a number of analytical approaches that are being considered for application to the
different data sets, including statistical (e.g., linear and non-linear models) and physical based
methods (including utilization of MODFLOW). These are being evaluated as part of the GW
analysis and will be applied based on data type, data suitability and specific IFS objectives (e.g.,
need for groundwater discharge data at selected locations in Focus Area for SRH-2D input,
versus need for groundwater temperature data at different locations). The objective for this TM
was to first, highlight empirically derived relationships between surface water elevations at two
locations in FA-128 and groundwater elevations at one location in FA-128 with Susitna River
discharge (based on Gold Creek gage) and then demonstrate how those data and data from FA-
138 could be used to develop predictive response functions to evaluate Project effects.
Ultimately, the development of these types of functions will need to be done with consideration
for their transferability to areas outside of the Focus Areas.
4.2.1. FA-128 (Slough 8A)
The hydrologic relationships for select hydrologic conditions between the flow in the Susitna
River at Gold Creek and stage in Middle Side Channel 8A at the lower aquatic transect are
shown in Figure 4.2-27. The use of selected comparison points show a period during low
Susitna River flows levels (below about 18,000 cfs) when there is no clear relationship to flow in
the main channel and stage conditions are controlled by groundwater inflow. Above this point
the relationship characteristics show a difference between rising and falling stage conditions in
the mainstem and between 2013 and 2014. The lower pattern of data points is from 2013. The
upper pattern is from 2014. A potential shift in the channel may have occurred between the two
time periods.
At the lower end of Slough 8A, just above the confluence with Middle Side Channel 8A water
levels are measured at station ESSFA128-1. Figure 4.2-28 shows the response pattern between
the flow at the Susitna River at Gold Creek and the lower end of Slough 8A. This portion of the
slough is in the backwater influence of Middle Side Channel 8A and shows a similar pattern of
response as Middle Side Channel 8A. The stage conditions are impacted by backwater
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
conditions up to approximately 18,000 cfs and the response to rising and falling discharge and
stage conditions is uniform until approximately 30,000 cfs on the Susitna River at Gold Creek.
In the upper aquatic cross section a well that was located adjacent to the slough and on the LB
(ESGFA128-18, Figure 4.2-29) was used for comparison. This reach of Slough 8A is above any
backwater influences from the Middle Side Channel 8A. At this location, there is no indication
of a response relationship until the mainstem Susitna River reaches about 36,000 cfs. Stage
conditions below about 36,000 cfs in the Susitna River remain around 575 feet above sea level.
As an additional step to understanding how mainstem flow influences Focus Area FA-128
(Slough 8A), Susitna flow at Gold Creek was compared to water surface elevations in the
ESGFA128-13 side channel location downstream of slough 8A. The entire 2014 ice-free season
was examined on an hourly basis from break-up in early May through the latest data downloads
on September 4, 2014. This represents a continuous record during the ice-free season that will be
expanded in forthcoming analyses to include the entire flow recession period until freeze-up
(September through November). The relationship between Susitna River flow at Gold Creek and
the ESGFA128-13 water surface elevation showed a threshold response over this period (Figure
4.2-30). Below about 16,000 cfs, 128-13 surface water elevation changed slightly, ranging
between 570.3 and 570.5 ft. However, above 16,000 cfs the stage response was linearly related
to Susitna mainstem flow and rose steadily from 570.2 and 573.8 ft. Linear regression was
highly significant for flow and stage relationships above and below the 16,000 cfs threshold (p <
0.0001), but explained more of the relationship above 16,000 cfs (R2 = 0.99) compared to below
the 16,000 cfs threshold (R2 = 0.15).
4.2.2. FA-138 (Gold Creek)
Susitna River at Gold Creek flow was also compared to water surface elevations in the
ESGFA138-2 Upper Side Channel 11 location within Focus Area FA-138 (Gold Creek) (Figure
4.2-31). This analysis included the ice free period from July 31 2013 to September 5 2014. The
relationship between Susitna Flow at Gold Creek and the ESGFA138-2 water surface elevation
showed three flow and stage responses over this period. Below 9,000 cfs, ESGFA138-2 surface
water elevation changed very slightly, ranging less than a tenth of a foot between 682.3 and
682.3. From 9,000 to 15,000 cfs, flow increased linearly from 682.3 to 683.3 ft while above
15,000 cfs 138-2 water elevation increased over three feet from 683.3 to 686.6. Linear
regression was highly significant for flow and stage relationships for each flow range and stage
range. (p < 0.0001), but explained more of the relationship above 15,000 cfs (R2 = 0.99)
compared to 9,000 to 15,000 cfs (R2 = 0.97) or below 9,000 cfs (R2 = 0.15).
4.3. GW/SW Relationships to Aquatic Habitat Functions
A further step in the analysis serves to illustrate GW/SW dynamics in two locations, FA 128-13
(noted in Figure 2.0-5) and FA138-2 (noted in Figure 2.0-8), respectively, with contrasting
downwelling and upwelling and hydrologic conditions as evidenced by thermal gradients. These
gradients are biologically significant in that they can influence egg and alevin development and
survival during the late fall, winter, and spring break-up periods. Understanding the GW/SW
dynamics under natural flow conditions will be important for determining how these dynamics
may change with Project operations. These and other intermediary types of GW/SW dynamics
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
are likely present within each of the Focus Areas and will be evaluated through further data
analysis.
4.3.1. ESGFA128-13 – Middle Side Channel 8A– Downwelling Dynamics
ESGFA128-13 in the Lower Side Channel below Slough 8A represents a downwelling site
where water temperatures in surface and sub-surface are near freezing throughout the winter
period (Figure 4.3-32). Sub-surface water and well temperatures dropped from ~4ºC to less than
1ºC in late November and remained low until break-up in early May. The exception to
consistently low temperatures was a slight temperature increase (to 1-2ºC) during mid-January
associated with a stage increase and a brief positive hydraulic gradient (i.e., when well WSE >
surface water WSE from Jan 01 to Jan 14). After this brief warming event, temperatures in
surface and sub-surface waters remained low for the next three months. Surface temperatures
increased at a greater rate in May while sub-surface sites remained ~2ºC. Consistent warming of
surface and sub-surface waters was observed in late June and was associated with increases in
Susitna River mainstem flow as well as surface water elevation stages (WSE). Maximum
temperatures for surface and sub-surface waters coincided with maximum Susitna River
mainstem flow (>40,000 cfs) in late June and early July. Well temperature response generally
lagged behind surface water, reaching a maximum in late August. All well, surface and sub-
surface water temperatures declined at a similar rate in early September to the end of the period
of record. Overall, the average winter temperature (November 1, 2013 to May 1, 2014) at
presumed embryo incubation depths (-20 to -50 cm) was 0.5ºC and average annual temperature
at these depths was 3.0ºC. This type of information will feed into the effective spawning and
incubation habitat models.
4.3.2. ESGFA138-2 – Upper Side Channel 11 – Upwelling Dynamics
ESGFA138-2 in Upper Side Channel 11 represents an upwelling site where water temperatures
remain above freezing for most of the winter period (2-4ºC, see Figure 4.3-33). The exception is
between December 11 and 19, 2013 when water from the mainstem flow breached the side
channel, the surface and well water surface elevations (WSE) increased approximately six feet,
and water temperatures through the streambed profile dropped to near freezing (0 to 1ºC).
Following this event, water temperatures in the sub-surface returned to warmer temperatures (2-4
ºC) until the break-up period in early May when surface and streambed profile temperatures
again decreased to near freezing (0 to 1ºC). Following the breakup period, near surface and
surface temperatures rose steadily, but the deeper profile between -50 and -100 cm remained
below 5 ºC. Over the entire annual period, sub-surface temperatures were related to the
differential between well and surface water elevations. During most of the winter period, well
WSE was greater than surface WSE (a positive vertical hydraulic gradient), and upward
groundwater flow to the stream maintained warm sub-surface temperature similar to
groundwater temperatures (~4ºC). Again, the exception was during breaching flows in
December when surface WSE was greater than well WSE, and sub-surface temperatures were
driven by downwelling from surface water. Overall, the average winter temperature (Nov 1 to
May 1) at embryo incubation depth (-20 to -50 cm) was 3.5ºC and average annual temperature at
these depths was 3.2ºC.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
5. GROUNDWATER AND SURFACE WATER RELATIONSHIPS IN
LATERAL HABITATS
The results of the current analysis support the same general conclusion reached during the 1980s
studies that:
“The results of the present study (1980s studies) do not permit a single model to be formulated
which can describe the discharge and temperature variations which are observed at each of the
various sloughs studied. The hydraulic and thermal behavior of each slough is substantially
different from that of other sloughs studied” (Harza-Ebasco, 1984).
Variability in GW/SW responses relative to mainstem flow was observed temporally at the same
locations and spatially at different locations within each Focus Area, as well as between Focus
Areas. However, the results presented herein have served to highlight some of the more
important mechanisms by which groundwater and surface water conditions can be influenced by
Susitna River flows.
These include the occurrence of breaching flows that may occur frequently relative to side
channel habitats; infrequently in slough habitats. Depending on their timing, magnitude and
duration, the occurrence of these flows during biologically sensitive periods could for example
influence overall egg survival and/or fry emergence timing within a given habitat location via
changes in water temperatures. Thus, determining how Project operations may influence the
frequency of these types of flows will be important for determining overall project effects.
Another apparent influencing mechanism pertains to winter freeze-up and ice disturbance, during
which stage increases can create substantial relatively short-term pulses in GW and SW levels.
This process can impart some of the same effects as breaching flows in terms of temperature
alterations. Of note too is the relatively low flow, stable conditions that occur during winter
periods when ice is not an influencing factor. During these times, the contribution of
groundwater to sloughs and side channels becomes the most pronounced and potentially most
influential to prevailing biological elements.
The analysis presented in this TM that was centered on FA-128 (Slough 8A) and FA-138 (Gold
Creek) has contributed to the overall understanding of GW/SW interactions and other (e.g., local
precipitation) mechanisms and types of functional relationships that can be derived from
empirical data. Both of the response functions for FA-128 (Figure 4.2-30) and for FA-138
(Figure 4.2-31) suggest that the influence of mainstem versus groundwater flows varies
depending on certain threshold or breaching flows in the mainstem river. In the case of FA-128
(Figure 4.2-30), this threshold occurs when mainstem flows > 16,000 cfs. At flows < 16,000 cfs,
the flow in that particular location is governed largely by groundwater. For FA-138 (Figure 4.2-
31), three separate relationships were identified: (1) flows < 9,000 cfs in which groundwater is
the dominant flow; (2) flow relationships between about 9,000 cfs and 15,000 cfs that are
mainstem controlled; and (3) flow relationships > 15,000 cfs where the relationship between
Susitna River at Gold Creek flow and stage in the side channel change slope. Analysis is
ongoing to identify these types of relationships at other locations within these and other Focus
Areas.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Establishment of these types of relationships will be important for analyzing Project effects over
time. For example, the general range of operations of the Project during the winter months is
anticipated to be from about 5,000 to 11,000 cfs, a period when natural flow conditions are
generally at their lowest (average winter-time flows at Gold Creek < 2,000 cfs). Thus, during the
winter months such flows would be substantially higher than what would naturally occur, but in
terms of the lateral habitats, may still be below the threshold flows for which main channel flows
become dominant. When project operation flows are below breaching thresholds, they would
have little to no effect on lateral habitats in terms of additional main channel flows, but the
hydraulic gradients imparted by the higher than normal main channel flows would likely be
greater and may result in increased upwelling zones within those habitats. In these transitional
types of areas, the temperatures associated with the upwelling areas would likely represent
combinations of groundwater and riverine source water.
The accompanying thermal analysis (based on temperature data collected from October 2013 to
early September 2014) for the two locations demonstrated two extremes in terms of areas that are
subject to downwelling and upwelling conditions. While Slough 8A within FA-128 (Slough 8A)
is a known spawning area, the location of the ESGFA128-13 station is below the confluence of
the Middle Side Channel 8A which received substantial flow from the Susitna mainstem (R2
2014b). As a result, this mainstem water dominated the sub-surface dynamics of the side
channel. An overall negative vertical hydraulic gradient at this location (Surface water WSE >
Groundwater WSE), indicates that downwelling from the surface water is the dominant
hydrologic pathway. Surface water movement from the side channel to the ESGFA128-13 well
may also maintain low well temperatures at ESGFA128-13 throughout the winter period.
Groundwater temperatures in the ESGFA128-13 W1 and W2 well positions during mid-winter
(~1ºC) were colder than ESGFA128-20 and ESGFA128-21 wells (2-4ºC; Figure 2.0-5)
positioned on the opposite side of the transect. Although wells ESGFA128-20 and ESGFA128-
21 are located on an island between slough 8A and the main channel, they appear to be less
affected by mainstem flow. The downwelling dynamics at the ESGFFA128-13 side channel
position resulted in greater temperature variability throughout the year. Winter temperatures
were near freezing, but surface and sub-surface temperatures increased after mid-June. Although
the average annual temperatures at incubation depth (3ºC) was likely adequate to support embryo
development, cold winter temperatures (Nov to May 1 average = 0.5ºC) that were often near
freezing or even supercooled to below freezing would result in slower development and potential
embryo mortality at this site. These flow and temperature dynamics highlight how cold
temperatures from Susitna mainstem flow can influence off-channel habitats throughout the
winter period.
In contrast, Upper Side Channel 11 in FA-138 (Gold Creek), which is a known chum salmon
spawning area was demonstrated to contain an area of upwelling. Many juvenile salmonids were
documented during summer and winter studies in this channel by studies FDA 6.5 and IFS 8.5
(R2 2014b; R2 and LGL 2014a, b), and chum fry were observed emerging from the substrate in
April 2014 (R2 2014b) Sub-surface temperatures at FA-138 were higher throughout the winter
period (Nov to May 1 average = 3.5ºC) and upwelling dynamics in this off-channel habitat may
be crucial for survival and successful development of salmon embryos as well as juvenile
rearing. Nevertheless, winter groundwater elevation and surface-water stage and temperature
time series records also demonstrate how hydrologic variability can result in pulses of cold sub-
surface temperatures in a dominant upwelling site. Surface water elevations increased rapidly
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
during mid-December from breaching likely associated with mainstem ice formation following
an early December warming event. During this breaching period, sub-surface temperatures
became isothermic and supercooled throughout much of the 100 cm sub-surface profile,
dropping to below freezing for a six day period. Such conditions are not conducive to embryo
development, but the extent of embryo impacts is dependent on the duration of occurrence as
well as the specific location of embryos within the substrate relative to the cold temperatures.
Since fry emergence was observed during April at this location, at least some (perhaps the
majority) of the salmon embryos were able to survive throughout the winter period.
More broadly, the analysis has identified dominant hydrologic periods that need to be considered
in terms of GW/SW relationships (Figure 5.0-34). High flow or downwelling periods may result
in cold or warm temperature conditions in the sub-surface. Cold sub-surface conditions are
observed when ice jams divert cold water from mainstem flows or generate backwater effects to
raise surface water elevations across a broad area. An increase in the hydraulic head or pressure
from rising surface waters forces water to infiltrate into the hyporheic zone and outward from the
channel to the surrounding groundwater aquifer. Overall, ice disturbance effects may occur
during fall freeze-up, mid-winter or spring break-up ice jams. Conversely, warm sub-surface
water may also be associated with high stage and downwelling periods from summer high flow
periods when Susitna water temperatures often reach an annual maximum (Tetra Tech and URS
2013). The types and degree of influence that groundwater has within a given lateral habitat will
vary depending on the specific hydrologic period. In the low stage period during winter and late
summer (see bottom panel in Figure 34), groundwater levels, elevated from local precipitation or
stored from prior mainstem flow events, are greater than surface water elevations and upwelling
conditions would dominant flow in lateral habitats. During the freeze-up and ice-jam periods,
groundwater dominance may alternate with surface water dominance depending on the degree of
ice staging. The spring break-up period represents a time of transition for lateral habitats that are
groundwater low-stage dominated to those riverine high-stage dominated as ice-out occurs and
flows increase. And finally, during mid-summer when flows are normally high, mainstem flows
dominate but can become less important during late summer as flow recedes.
Despite seasonal changes in hydrology due to ice disturbance and flooding, lateral habitats with
groundwater influence and upwelling act to moderate sub-surface temperature dynamics by
maintaining temperatures above freezing during winter as well as attenuating the rise in
temperature during the summer period. The two sets of analysis presented in this TM
demonstrate how mainstem flow rates, seasonal ice disturbance, and local GW/SW hydrologic
conditions in off-channel habitats can influence sub-surface temperature conditions that are
critical for embryo development, and the reproductive success of anadromous salmonids and
resident fish species. The overall extent to which lateral habitats will be modified under Project
operations depends on the relative change of winter and summer mainstem flows, the change in
mainstem temperatures during winter and summer, and the extent and duration of ice disturbance
during freeze-up, mid-winter and break-up periods.
6. PLANS FOR 2015
The GW studies associated with Task 6 will continue in 2015 with a focus on a) collection of
hydrologic data (surface and groundwater) within FA-104 (Whiskers Slough), FA-113 (Oxbow
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
1), FA-115 –(Slough 6A), FA-128 (Slough 8A), FA-138 (Gold Creek), FA-141 (Indian River),
and FA-144 (Slough 21); b) continued analysis of empirical data and development of GW/SW
relationships; c) completion of MODFLOW modeling to support data analysis; and d)
development of specific groundwater related parameter inputs needed to support the IFS-FA
models as well as other modeling efforts (e.g., Water Quality Model (Study 5.6); Fluvial
Geomorphology Model (Study 6.6); Ice Processes (Study 7.6).
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SYSTAT Software Inc., 2002. TableCurve 2D, Version 5.0 for Windows
Tetra Tech. 2014. Fluvial Geomorphology Modeling. PowerPoint Presentation, Riverine
Modeling Proof of Concept Meetings on April 15-17, 2014. Prepared for Alaska Energy
Authority, Anchorage, Alaska. Susitna-Watana Hydroelectric Project, FERC No. P-
14241. http://www.susitna-watanahydro.org/meetings/past-meetings/.
Tetra Tech and URS. 2013. Water Quality Studies Baseline Monitoring, Focus Areas, and
Modeling. PowerPoint Presentation, Technical Workgroup Meeting, December 2, 2013.
Prepared for Alaska Energy Authority, Anchorage, Alaska. Susitna-Watana
Hydroelectric Project, FERC No. P-14241. http://www.susitna-watanahydro.org/wp-
content/uploads/2013/12/2013-12-02TWG_Water-Quality.pdf.
Trihey, E.W. 1982. 1982 Winter Temperature Study. Prepared for Acres American, Inc. by E.W.
Trihey, Anchorage, Alaska. 151 pp. APA Document 526.
Turnipseed, D.P., and Sauer, V.B., 2010, Discharge measurements at gaging stations: U.S.
Geological Survey Techniques and Methods book 3, chap. A8, 87 p.
USGS (U.S. Geological Survey). 2005. MODFLOW-2005, The U.S. Geological Survey
modular ground-water model—the Ground-Water Flow Process: U.S. Geological Survey
Techniques and Methods 6-A16.
USGS. 2014. USGS Period of Record Daily Mean Flow Statistics for Susitna River at Gold
Creek (Station 15292000), accessed August 30, 2014, at
http://waterdata.usgs.gov/ak/nwis/dvstat?referred_module=sw&search_site_no=1529200
0&format=sites_selection_links
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Vining, L. J., J. S. Blakely, and G. M. Freeman. 1985. An evaluation of the incubation life-phase
of chum salmon in the middle Susitna River, Alaska. Winter Aquatic Investigations,
September 1983 – May 1984. Report No. 5, Volume 1, Alaska Department of Fish and
Game Susitna Hydro Aquatic Studies. Prepared for Alaska Power Authority, Anchorage,
Alaska. 232 pp. APA Document # 2658.
Winter, T.C. 2001. The concept of hydrologic landscapes. Journal of the American Water
Resources Association 37: 335-349.
Woodward-Clyde. 1984. Fish Mitigation Plan. Susitna Hydroelectric Project. Document No.
2466. Settlement Document. Alaska Power Authority.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
8. TABLES
Table 3.1-1. Locations of discharge measurements recorded in FA-104 (Whiskers Slough), FA-128 (Slough 8A) and FA-
138 (Gold Creek) during March and April 2014.
Site Focus Area Habitat Type Site Location Description
FA104-PIT 104 SS Whiskers slough at ESGFA104-9-W2
FA104-SL 3B 104 SC Slough 3B near WS50-WQ5-OG
FA104 SL INL 104 SS Whiskers Slough Inlet
FA104-10 104 SC Whiskers Side Channel at ESGFA104-10-W1
FA104-5 104 SS Whiskers Slough at ESGFA104-5
FA104-ET 104 SC Whiskers East Side Channel near inlet
FA104-E 104 SC Whiskers East Side Channel
FA104-SL 3A 104 US Slough 3A
FA128-SL 8A INL 128 SS Slough 8A Inlet below camp
FA128-18 SL 8A 128 SS Slough 8A upstream ESGFA128-18-W1
FA128-SC 128 SC Side channel downstream of ESGFA128-13-W1
FA128-SL A 128 SS Slough A
FA128-HM 128 US Half-moon slough
FA138-4 USC11 138 SC Upper Side Channel 11
FA138-SL 11 GC 138 SS Upper Side Channel 11 inlet
FA138-SL 13 138 SS Slough 13
FA138-SC 11 138 SC Lower Side Channel below Slough 11 outlet
FA138-3 SL 11 138 SS Slough 11 near ESGFA138-3
FA138-SL 11 INL 138 SS Inlet Slough 11
* SC = Side Channel, SS = Side slough, US = Upland Slough
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Table 3.1-2. Instream Flow Study discharge measurement summary table.
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9. FIGURES
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 2.0-1. Susitna Watershed basin boundaries, showing the Project designation of upper, middle and lower river segments.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 2.0-2. Susitna Watershed Middle River Segment, with geomorphic reaches and Focus Areas indicated.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 2.0-3. General location of FA-128 (Slough 8A) Focus Area, showing major data collection stations and aquatic and riparian transects.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 2.0-4. Inset A shows locations of aquatic transect stations with continuously measured parameters at FA-128 (Slough 8A) Focus Area.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 2.0-5. Inset B shows locations of aquatic transect stations with continuously measured parameters at FA-128 (Slough 8A) Focus Area.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 2.0-6. Inset C shows locations of aquatic transect stations with continuously measured parameters at FA-128 (Slough 8A) Focus Area.
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Figure 2.0-7. General location of FA-138 (Gold Creek) Focus Area, showing major data collection stations and aquatic and riparian transects.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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Figure 2.0-8. Inset A shows locations of aquatic transect stations with continuously measured parameters at FA-138 (Gold Creek) Focus Area.
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Figure 2.0-9. Inset B shows locations of aquatic transect stations with continuously measured parameters at FA-138 (Gold Creek) Focus Area.
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Figure 3.2-10. Period of Record Flow Conditions for Susitna River at Gold Creek and Annual Hydrologic Periods.
Figure 3.2-11. 2013 Discharge hydrograph for the Susitna River at Gold Creek (USGS 1529200) with selected periods
(points of interest) shown used for response function analysis.
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Figure 3.2-12. 2014 Discharge hydrograph for the Susitna River at Gold Creek (USGS 1529200) with selected periods
(points of interest) shown used for response function analysis.
Figure 4.1-13. Cross-section diagram showing Lower Aquatic Transect on Middle Side Channel 8A, with groundwater
stations ESGFA128-13, ESGFA128-20, and ESGFA128-21. Wells are shown and water levels and channel water level for
April 22, 2014.
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Figure 4.1-14. Groundwater Station ESGFA128-13 groundwater levels in wells adjacent to Middle Side Channel 8A and
surface-water stage in Middle Side Channel 8A, and groundwater levels from wells at ESGFA128-20 and ESGFA128-21.
Figure 4.1-15. Groundwater Station ESGFA128-13 groundwater temperature in wells adjacent to Middle Side Channel
8A and surface-water temperature in Middle Side Channel 8A, and groundwater temperature from wells at ESGFA128-
20 and ESGFA128-21.
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Figure 4.1-16. Groundwater Station ESGFA128-13 select streambed temperature profile measurements in Middle Side
Channel 8A.
Figure 4.1-17. Cross-section diagram showing Upper Aquatic Transect on Slough 8A, with groundwater stations
ESGFA128-7, ESGFA128-18, and ESGFA128-19. Wells are shown and water levels and channel water level for April 22,
2014.
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Figure 4.1-18. Groundwater Station ESGFA128-7 groundwater levels in wells adjacent to Slough 8A and surface-water
stage in Slough 8A, and groundwater levels from wells at ESGFA128-18 and ESGFA128-19.
Figure 4.1-19. Groundwater Station ESGFA128-7 groundwater temperature in wells adjacent to Slough 8A and surface-
water temperature in Slough 8A, and groundwater temperature from wells at ESGFA128-18 and ESGFA128-19.
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Figure 4.1-20. Groundwater Station ESGFA128-7 select streambed temperature profile measurements in Slough 8A.
Figure 4.1-21. Groundwater Station ESGFA128-6 groundwater levels in wells adjacent to Slough 8A and surface-water
stage in Slough 8A, and groundwater levels from wells at ESGFA128-18 and ESGFA128-19.
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Figure 4.1-22. Groundwater Station ESGFA128-6 groundwater temperature in wells adjacent to Slough 8A and surface-
water temperature in Slough 8A, and groundwater temperature from wells at ESGFA128-18 and ESGFA128-19.
Figure 4.1-23. Groundwater Station ESGFA138-1 groundwater levels in wells adjacent to Slough 11 and surface-water
stage in Slough 11.
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Figure 4.1-24. Groundwater Station ESGFA138-1 groundwater temperature in wells adjacent to Slough 11 and surface-
water temperature in Slough 11.
Figure 4.1-25. Groundwater Station ESGFA138-2 groundwater levels in wells adjacent to Slough 11 and surface-water
stage in Slough 11.
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Figure 4.1-26. Groundwater Station ESGFA138-2 groundwater temperature in wells adjacent to Slough 11 and surface-
water temperature in Slough 11.
Figure 4.2-27. Susitna River at Gold Creek (USGS 1529200) discharge compared with Middle Side Channel 8A stage
conditions on the Lower Aquatic Transect in FA-128 (Slough 8A) at ESGFA128-13. Selected data are from summer (ice-
free) conditions.
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Figure 4.2-28. Susitna River at Gold Creek (USGS 1529200) discharge compared with Slough 8A stage conditions above
confluence with the Middle Side Channel 8A and the Lower Aquatic Transect in FA-128 (Slough 8A) at ESSFA128-1.
Selected data are from summer (ice-free) conditions.
Figure 4.2-29. Susitna River at Gold Creek (USGS 1529200) discharge compared with Slough 8A adjacent groundwater
conditions at the Upper Aquatic Transect in FA-128 (Slough 8A) at ESGFA128-18. Selected data are from summer (ice-
free) conditions.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 4.2-30. Analysis example for the response between flow conditions at Susitna River at Gold Creek and the Middle
Side Channel 8A located at the Lower Aquatic Transect in FA-128 (Slough 8A). The example demonstrates the
relationship of stage data for summer (ice free conditions).
Figure 4.2-31. Analysis example for the response between flow conditions at Susitna River at Gold Creek and the Upper
Side Channel 11 located at the Upper Aquatic Transect in FA-138 (Slough 11). The example demonstrates the
relationship of stage data for summer (ice free conditions).
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Figure 4.3-32. Downwelling example in Middle Side Channel 8A in FA-128 (Slough 8A) showing groundwater and
surface-water levels, stream-bed temperatures, and thermal profile of the stream bed conditions through the major
hydrologic periods.
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Figure 4.3-33. Upwelling example in Upper Side Channel 11 in FA-138 (Gold Creek) showing groundwater and surface-
water levels, stream-bed temperatures, and thermal profile of the stream bed conditions through the major hydrologic
periods.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Figure 5.0-34. Conceptual model of groundwater-surface water interactions and the thermal regime occurring under high stage and low stage conditions within lateral
habitats of the Susitna River.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
APPENDIX A. HYDROLOGIC STATIONS PRIMARY STATION
PURPOSE, LOCATION AND DATA COLLECTION PARAMETERS
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 1. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-144 (Slough 21).
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 2. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-141 (Indian River).
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 3. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-138 (Gold Creek).
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 4. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-128 (Slough 8A).
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 4. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-128 (Slough 8A), continued.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 5. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-115 (Slough 6A).
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 6. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-113 (Oxbow 1).
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 7. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
PRM 112 (Slough 6).
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 8. Groundwater Study primary station purpose, location and data collection parameters for hydrologic stations at
FA-104 (Whiskers Slough).
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
APPENDIX B. APRIL 2014 DISCHARGE MEASUREMENTS
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 1. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XUS, April 18-19, 2014.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 1 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 1. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XUS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 2 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 1. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XUS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 1. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XUS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 4 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 1. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XUS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 5 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 1. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XUS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 6 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 2. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XDS, April 18-19, 2014.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 7 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 2. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XDS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 2. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XDS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 9 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 2. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XDS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 2. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XDS, April 18-19, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 2. Groundwater Study discharge measurements at FA-138 (Gold Creek), location S11XDS, April 18-19, 2014, continued.
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Table 3. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2US, April 21, 2014.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 3. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2US, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 3. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2US, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 3. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2US, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 3. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2US, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 3. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2US, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 4. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2DS, April 21, 2014.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 19 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 4. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2DS, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 4. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2DS, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 4. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2DS, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 4. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2DS, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 4. Groundwater Study discharge measurements at FA-128 (Slough 8A), location S8AX2DS, April 21, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 5. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXUS, April 17, 2014.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 25 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 5. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXUS, April 17, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix B - Page 26 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 5. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXUS, April 17, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 5. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXUS, April 17, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 5. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXUS, April 17, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 5. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXUS, April 17, 2014, continued.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 6. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXDS, April 17, 2014.
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Table 6. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXDS, April 17, 2014, continued.
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Table 6. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXDS, April 17, 2014, continued.
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Table 6. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXDS, April 17, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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Table 6. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXDS, April 17, 2014, continued.
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Table 6. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location WCXDS, April 17, 2014, continued.
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Table 7. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location 3AUS, April 16, 2014.
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Table 7. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location 3AUS, April 16, 2014, continued.
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Table 7. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location 3AUS, April 16, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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Table 7. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location 3AUS, April 16, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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Table 7. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location 3AUS, April 16, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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Table 7. Groundwater Study discharge measurements at FA-104 (Whiskers Slough), location 3AUS, April 16, 2014, continued.
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Table 8. Groundwater Study discharge measurements at FA-104 (Whiskers Slough) at station ESGFA104-9, location WSX, April 26, 2014.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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Table 8. Groundwater Study discharge measurements at FA-104 (Whiskers Slough) at station ESGFA104-9, location WSX, April 26, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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Table 8. Groundwater Study discharge measurements at FA-104 (Whiskers Slough) at station ESGFA104-9, location WSX, April 26, 2014, continued.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Table 8. Groundwater Study discharge measurements at FA-104 (Whiskers Slough) at station ESGFA104-9, location WSX, April 26, 2014, continued.
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APPENDIX C. 2014 GROUNDWATER STUDY RESPONSE ANALYSIS
TIME-LAPSE IMAGE DATA AT SITE ESSFA128-1
The following set of images shows a time sequence of images from station ESSFA128-1, located
in FA-128 (Slough 8A) on the lower portion of Slough 8, at the junction of Slough 8A and
Middle Side Channel 8A. The station condition is influenced by backwater effects from the side
channel under certain flow conditions.
The image data series shows the surface-water conditions at each point of analysis being
considered for evaluation of response functions.
The date and time in the headers of all images are in Alaska Standard Time (AST). Additional
images may be available for other flow conditions.
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The following set of graphs and images show conditions on
Slough 8A at the ESSFA128-1.
ESSFA128-1 Location
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
The following set of images show conditions on Slough 8A at
the preliminary discharge points of interest for 2013.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
The following set of images show conditions on Slough 8A at
the preliminary discharge points of interest for 2014 (as of
20140716.
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Example Photo Showing
Low-Water Channel Conditions
Slough 8A
Middle Side
Channel 8A
Confluence
Flow
Direction
General Location of Water Level Measurement
Susitna River at Gold Creek –Q = 8,070 CFS (Rising), Stage = 7.24 ft. @ 08:00 AST
ESSFA128-1 (Slough 8A) –Stage = 571.12 ft., Temperature = 3.3°C
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
8/19/2013
Susitna River at Gold Creek –Q = 20,200 CFS (Rising), Stage = 9.95 ft. @ 11:15 AST
ESSFA128-1 (Slough 8A) –Stage = 571.35 ft., Temperature = 7.8°C
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 30,600 CFS (Rising), Stage = 11.46 ft. @ 05:45 AST
ESSFA128-1 (Slough 8A) –Stage = 572.87 ft., Temperature = 7.9°C
8/21/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 6 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 41,400 CFS (Rising), Stage = 12.71 ft.@ 13:30 AST
ESSFA128-1 (Slough 8A) –Stage = 574.24 ft., Temperature = 8.3°C
8/21/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 49,000 CFS (Peak), Stage = 13.46 ft.@ 00:00 AST
ESSFA128-1 (Slough 8A) –Stage = 575.98 ft., Temperature = 8.5°C
8/22/2013
Image is 5:01 hours after reported flow and stage values
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 39,600 CFS (Falling), Stage = 12.52 ft.@ 17:00 AST
ESSFA128-1 (Slough 8A) –Stage = 574.39 ft., Temperature = 9.2°C
8/23/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 29,400 CFS (Falling), Stage = 11.31 ft.@ 11:00 AST
ESSFA128-1 (Slough 8A) –Stage = 573.05 ft., Temperature = 6.1°C
8/25/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 10 September 2014
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Susitna River at Gold Creek –Q = 21,800 CFS (Falling), Stage = 10.21 ft.@ 20:45 AST
ESSFA128-1 (Slough 8A) –Stage = 571.90 ft., Temperature = 7.0°C
8/26/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 24,400 CFS (Rising), Stage = 10.61 ft.@ 12:30 AST
ESSFA128-1 (Slough 8A) –Stage = 572.23 ft., Temperature = 6.5°C
9/2/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 12 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 30,000 CFS (Rising), Stage = 11.39 ft.@ 09:00 AST
ESSFA128-1 (Slough 8A) –Stage = 573.05 ft., Temperature = 6.2°C
9/4/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 13 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 32,000 CFS (Peak), Stage = 11.64 ft.@ 21:00 AST
ESSFA128-1 (Slough 8A) –Stage = 573.46 ft., Temperature = 6.5°C
9/4/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 14 September 2014
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Susitna River at Gold Creek –Q = 29,700 CFS (Falling), Stage = 11.35 ft.@ 19:15 AST
ESSFA128-1 (Slough 8A) –Stage = 573.16 ft., Temperature = 6.4°C
9/13/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 15 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 21,900 CFS (Falling), Stage = 10.22 ft.@ 09:15 AST
ESSFA128-1 (Slough 8A) –Stage = 572.04 ft., Temperature = 4.6°C
9/15/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 16 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 18,000 CFS (Falling), Stage = 9.55 ft.@ 03:00 AST
ESSFA128-1 (Slough 8A) –Stage = 571.32 ft., Temperature = 5.1°C
9/17/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 17 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 16,000 CFS (Falling), Stage = 9.17 ft.@ 11:00 AST
ESSFA128-1 (Slough 8A) –Stage = 571.11 ft., Temperature = 4.4°C
9/19/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 18 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 13,900 CFS (Falling), Stage = 8.75 ft.@ 16:00 AST
ESSFA128-1 (Slough 8A) –Stage = 571.07 ft., Temperature = 4.4°C
9/21/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 19 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 12,000 CFS (Falling), Stage = 8.31 ft.@ 17:30 AST
ESSFA128-1 (Slough 8A) –Stage = 571.05 ft., Temperature = 4.9°C
9/23/2013
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 20 September 2014
TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 8,960 CFS (Falling), Stage = 7.51 ft.@ 10:45 AST
ESSFA128-1 (Slough 8A) –Stage = 571.19 ft., Temperature = 3.7°C
10/4/2013
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TECHNICAL MEMORANDUM GROUNDWATER AND SURFACE WATER AQUATIC HABITAT STUDIES
Susitna River at Gold Creek –Q = 7,030 CFS (Rising), Stage = 6.90 ft.@ 00:00 AST
ESSFA128-1 (Slough 8A) –Stage = 571.05 ft., Temperature = 3.0°C
10/27/2013
Image is 15:01 hours after reported flow and stage values
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix C - Page 22 September 2014