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Susitna‐Watana Hydroelectric Project Document
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1425
.S8
S92
no.289
sec.7.5
suppl.
Title:
SuWa 289
Groundwater study, Study plan Section 7.5, Upwelling broad-scale
mapping of the middle Susitna River technical memorandum
Author(s) – Personal:
Author(s) – Corporate:
R2 Resource Consultants, Inc.
AEA‐identified category, if specified:
October 24, 2016; AEA technical memoranda filings
AEA‐identified series, if specified:
Series (ARLIS‐assigned report number): Existing numbers on document:
Susitna-Watana Hydroelectric Project document number 289
Published by: Date published:
[Anchorage : Alaska Energy Authority, 2016] October 2016
Published for: Date or date range of report:
Prepared for Alaska Energy Authority
Volume and/or Part numbers: Final or Draft status, as indicated:
Study plan Section 7.5
Document type: Pagination:
Supplement ; Atlas 2 volumes
Related work(s): Pages added/changed by ARLIS:
see below
Notes:
Contents:
[Main report]
Appendix A. Locations of potential groundwater influenced areas within the middle Susitna
River.
This document represents:
Supplement to: Groundwater study, Study plan Section 7.5, 2014-2015 Study Implementation
Report. (SuWa 289)
Attachment 3 of: Response of the Alaska Energy Authority to Comments on the Initial Study
Report. (SuWa 299)
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/susitnadocfinder/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Groundwater Study
Study Plan Section 7.5
Upwelling Broad-Scale Mapping of the Middle Susitna
River Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
R2 Resource Consultants, Inc.
October 2016
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TABLE OF CONTENTS
1. Introduction ........................................................................................................................2
2. Study Objectives.................................................................................................................3
3. Background and Methods .................................................................................................4
3.1. Ice Processes Study - Thermal Open Leads .......................................................4
3.2. Water Quality Study - Thermal Infrared Imagery .............................................5
3.3. Instream Flow Study - Vertical Hydraulic Gradient ..........................................6
3.4. Historic Spawning Surveys and Upwelling .......................................................6
3.5. Data Analysis and Map Generation ...................................................................7
4. Results .................................................................................................................................7
5. Discussion and Conclusions ..............................................................................................8
6. References Cited...............................................................................................................10
7. Tables ................................................................................................................................12
8. Figures ...............................................................................................................................13
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LIST OF TABLES
Table 3-1. Summary of potential groundwater influenced areas by geomorphic reach in the
Susitna Middle River Segment. ............................................................................................ 12
LIST OF FIGURES
Figure 3-1. Example GIS process of converting 2012 Ice Study thermal open lead lines and
points to buffered areas in Upper Side Channel 11 and Slough 11, FA- 138 (Gold Creek). 14
Figure 3-2. Example GIS process of converting 1983 thermal open ice lead observation points to
buffered areas in Slough 8A and main channel habitat at PRM 128.6, FA-128 (Slough 8A).
............................................................................................................................................... 14
Figure 3-3. Example GIS process of converting 2012 thermal infrared imagery to increased
groundwater activity areas in Unnamed Tributary 117.4, Slough 8, Lane Creek, and main
channel habitat between PRM 117 and 118.8. ...................................................................... 15
Figure 3-4. Example GIS process of converting 2013-2014 Instream Flow Study HSC vertical
hydraulic gradient sample locations (points) and sample sites (lines) to buffered areas in
Side Channel 21, FA-144 (Slough 21). ................................................................................. 15
Figure 3-5. Example GIS process of converting 1982 open-water upwelling locations to buffered
areas in Slough 9 and Slough 9B, PRM 131.6 to PRM 132.6. ............................................. 16
Figure 3-6. Example GIS process of aggregating overlapping survey data to a single
groundwater activity polygon in Slough 19, Slough 20, and mainstem habitat from PRM
143.2 to PRM 143.5 at the upstream end of FA-141 (Indian River). ................................... 16
Figure 3-7. Longitudinal distribution of potential groundwater influenced areas in the Middle
River Segment of the Susitna River. See Appendix A for GIS delineations of specific
groundwater areas. ................................................................................................................ 17
Figure 3-8. Cumulative and Project River Mile based longitudinal distribution of potential
groundwater influenced areas in the Middle River Segment of the Susitna River. See
Appendix A for GIS delineations of specific groundwater areas. ........................................ 17
APPENDICES
Appendix A. Locations of Potential Groundwater Influenced Areas within the Middle Susitna
River
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LIST OF ACRONYMS AND SCIENTIFIC LABELS
ABBREVIATION DEFINITION
AEA Alaska Energy Authority
APA Alaska Power Authority
FA Focus Area
FERC Federal Energy Regulatory Commission
FLIR Forward Looking Infrared
GIS Geographic Information System
GPS Global Positioning System
GW/SW Groundwater/Surface Water
HSC Habitat Suitability Criteria
IFS Fish and Aquatics Instream Flow Study 8.5
ISR Initial Study Report
MR Middle Susitna River Segment, PRM 187.1 to PRM 102.4
PRM Project River Mile
Project Susitna-Watana Hydroelectric Project, FERC No. 14241
RIFS Riparian Instream Flow Study 8.6
RM River Mile or Historic River Mile
RMSE Root-Mean Square Error
RSP Revised Study Plan
SIR 2014-2015 Study Implementation Report
TIR Thermal Infrared Remote
TM Technical Memorandum
USR Updated Study Report
VHG Vertical Hydraulic Gradient
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1. INTRODUCTION
On December 14, 2012, Alaska Energy Authority (AEA) filed its Revised Study Plan (RSP) with
the Federal Energy Regulatory Commission (FERC or Commission) for the Susitna-Watana
Hydroelectric Project, FERC Project No. 14241 (Project), which included 58 individual study
plans (AEA 2012). Included within the RSP was the Groundwater Study (GW), Section 7.5. On
April 1, 2013 SPD, FERC approved the RSP with recommendations. As established in Study
Plan Section 7.51, the Groundwater Study is focused on providing an overall understanding of
groundwater/surface water (GW/SW) interactions at both the watershed- and local-scales. Study
Plan Section 7.5 also describes the study methods that would be used to evaluate Project effects
on GW/SW interactions and how those influences may impact riparian and aquatic habitats in the
Susitna River.
AEA filed the Initial Study Report Parts A, B, and C on June 3, 2014. Study 7.5 ISR Part A of
the Initial Study Report (ISR) details the development of the Groundwater Study from the
Revised Study Plan (RSP) in 2012, through the end of the 2013 study season. Study 7.5 ISR Part
C, Section 7 sets forth AEA’s plan and schedule, at that time, for completing this study and
meeting the objectives of the Study Plan. Two Technical Memoranda (TM) were prepared and
filed on September 30, 2014 that presented results of preliminary groundwater (GW)/surface
water (SW) analysis related to Groundwater Study Objective 5 that pertains to the Riparian
Instream Flow Study (RIFS) (Study 8.6) and Groundwater Study Objective 6 that pertains to the
Fish and Aquatics Instream Flow Study (IFS) (Study 8.5).
Study 7.5 ISR Part D was filed on November 6, 2015 and summarized the study status,
highlighted results, and achievements; listed and provided links to the Study 7.5 documents;
described variances and Study Plan modifications; and listed steps needed to complete the study.
The 2014-2015 Study Implementation Report was also filed on November 6, 2015 and contained
four appendices: (1) Appendix A: Preliminary Water Table Contour Maps for Focus Areas FA-
104 (Whiskers Slough), FA-115 (Slough 6A), FA-128 (Slough 8A), and FA-138 (Gold Creek); (2)
Appendix B: Preliminary MODFLOW Three Dimensional Groundwater Model for FA-128
(Slough 8A); (3) Appendix C: Summary Review of Susitna River Hydrogeologic Studies
Conducted in the 1980s with Relevance to Proposed Susitna-Watana Dam Project and other
Non-Project Related Studies; and (4) Appendix D: December 5, 2014 Technical Team Meeting
Notes and Presentation.
This Technical Memorandum (TM) (a supplement to Study 7.5 2014-2015 Study Implementation
Report (November 9, 2015) and filed with FERC as Attachment 3 to Response of the Alaska
Energy Authority to Comments on the Initial Study Report) describes and presents a GIS derived
1 The FERC-approved Revised Study Plan (RSP) Section 7.5 for the Groundwater Study as modified by FERC’s Study Plan
Determination (Study 7.5 SPD, April 1, 2013), the Riparian Instream Flow, Groundwater, and Riparian Vegetation Studies FERC
Determination Response Technical Memorandum (Study 7.5, 8.6, and 11.6 TM, July 1, 2013), the Selection of Focus Areas and
Study Sites in the Middle and Lower Susitna River for Instream Flow and Joint Resource Studies – 2013 and 2014 TM (Study 8.5
TM, March 1, 2013), and the Adjustments to Middle River Focus Areas TM (Study 8.5 TM, May 31, 2013) is collectively referred
to as Study Plan Section 7.5.
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map series that depicts groundwater influenced areas identified within the entire Middle River
Segment of the Susitna River.
Objective 4 of Groundwater Study 7.5 focused on groundwater upwelling, specifically targeting
the identification of groundwater influenced areas within the entire Middle River Segment of the
Susitna River. Information resulting from this study component was to include: 1) Geographic
Information System (GIS) map layer of upwelling and groundwater influenced areas; and 2)
analysis of the identified upwelling/spring areas to determine if they are (a) main flow/stage
dependent, (b) regional/upland groundwater dependent, or (c) of mixed influence.
One of the key groundwater related factors associated with aquatic habitats pertains to upwelling.
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
to promote embryogenesis, and also providing sustained or increased intergravel flows that
transport needed dissolved oxygen to and metabolic wastes from the developing embryos. The
importance of groundwater upwelling and determining GW/SW relationships was also noted
during the 1980s studies of the Su-Hydro Project 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). In addition, 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.
The information in this TM will be coupled with Focus Area-specific groundwater information,
and data from other resource studies (Fluvial Geomorphology Modeling Study 6.6; Ice Processes
Study 7.6; Fish and Aquatics Instream Flow (IFS) Study 8.5; and Riparian IFS (RIFS) Study 8.6)
to classify the identified groundwater areas based on dependencies on river, upland groundwater,
or mixed river/groundwater. The categorization or differentiation of groundwater types will be
completed and presented in the Updated Study Report (USR).
2. STUDY OBJECTIVES
Groundwater Study Plan objectives were established in RSP Section 7.5.1 (AEA 2012).
Objective 4 is to work with other resource studies to map groundwater-influenced aquatic and
floodplain habitat (e.g., upwelling areas, springs, groundwater-dependent wetlands) within the
Middle River Segment of the Susitna River, including within selected Focus Areas. The study
component relied on the following activities and work products from other resource studies:
• Aerial and global positioning system (GPS) mapping of winter open leads as completed
by the Ice Processes Study (Study 7.6);
2 Slough 8A is contained within Focus Area FA-128 (Slough 8A); Slough 11 is contained within FA-138 (Gold Creek). Slough 9 is
outside of the defined Focus Areas.
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• Aerial Thermal Infrared Imagery (TIR) as provided from a temperature mapping study as
part of Water Quality Study (Study 5.5);
• Observational data concerning GW/SW interactions collected as part of the Habitat
Suitability Criteria (HSC) studies associated with spawning and/or rearing fish conducted
under the Fish and Aquatics Instream Flow Study (Study 8.5); and
• Historic mapping of upwelling locations documented in 1982 and 1984, as appropriate.
This component of the Groundwater Study provides the compilation, review, and interpretation
of the different mapping work products and resulted in development of a GIS map layer
depicting potential groundwater influenced areas within the Middle River Segment of the Susitna
River.
3. BACKGROUND AND METHODS
The initial step of this analysis was comprised of gathering existing 2012-2014 resource study
data that may be used for the mapping process to determine which were most applicable for
defining groundwater sources in the Middle River Segment of the Susitna River. The second
step identified and selected a set of metrics that were used for distinguishing groundwater
sources for each of the data sets. These included both quantitative metrics such as temperature
differentials and vertical hydraulic gradient (VHG) measurements, as well as qualitative metrics
such as visual detections of clear water zones during the open-water periods, or open-water leads
during periods of ice cover. These metrics were used in the analysis of the data sets and served
to delineate areas of groundwater influence that were incorporated into GIS map layers. The
different sources of information utilized in this analysis are described below.
3.1. Ice Processes Study - Thermal Open Leads
The Susitna River Ice Processes Study Report (HDR 2013) documents the location of open-water
leads in the ice cover in late winter and during ice breakup. Open leads from Cook Inlet to the
Oshetna River (Project River Mile [PRM] 235.1) were mapped aerially and documented using
GPS-enabled cameras in March 2012, before temperatures rose above freezing, and in April
2012 during ice breakup. Leads were classified by location (main channel, side channel, slough,
or bank toe), type (thermal or velocity, where identifiable), disposition (continuous or
discontinuous) and spatial extent (linear or ice hole). In the case of linear open leads, the
upstream and downstream limits of each lead were located in the field using a handheld GPS
unit, and the width of each lead was estimated visually as a percentage of river width. Leads
classified as thermal in origin were generally shallow, located in marginal habitat areas and did
not appear from the air to have a strong current (HDR 2013).
For the groundwater analysis, only thermal open leads in the Middle River Segment were used.
This resulted in specific survey dates of March 21-22, 2012 for open leads located below Devils
Canyon and April 4, 2012 for leads above Devils Canyon. Linear open lead GIS lines and points
were re-delineated to fit within the habitat feature and then buffered by the average of the
upstream and downstream width to create an open lead area (Figure 3-1). Ice holes remain as
point features with no associated area.
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Another component of the 2012 Ice Processes Study 7.6 report (HDR 2013) was a literature
review of past studies documenting historic ice lead observations in the Susitna River. R&M
mapped open leads on March 2, 1983, between Rabideux Creek (PRM 87.2) and Devils Canyon
(approximately PRM 155.1) (Schoch 1984). R&M recorded the Historic River Mile 3 (RM) at
the upstream end, length, widest width, location (main channel, side channel, or slough), type
(thermal or velocity), and disposition (continuous or discontinuous). Leads classified as thermal
indicated that the lead was kept open by groundwater seepage (Schoch 1984, Table 4.9). As
before, only thermal open leads were used in the groundwater analysis. Using the recorded RM,
channel type, and open lead length, linear open leads were digitized and then buffered one-half
the widest width to create an open lead polygon (Figure 3-2).
The open lead surveys on March 12, 2013 and February 20-21 and April 2, 2014 were presented
in the Ice Processes Study 7.6, 2014-2015 Study Implementation Report (SIR) (HDR 2015). The
available GIS data at the time of this report were points and only classified by location and type
(thermal or velocity). The thermal locations remain as point features and represent general
presence or absence of open leads for the groundwater analysis.
3.2. Water Quality Study - Thermal Infrared Imagery
The 2012 Thermal Infrared Remote Sensing Pilot Test (URS 2013) documents locations with
large groundwater influence along the Susitna River from Talkeetna (PRM 100) to the proposed
Watana Dam site (PRM 187.1) using the differential in temperature between warm groundwater
and colder in-stream surface water. The survey was conducted on October 12-13, 2012 and
October 17-18, 2012. Images were collected with a Forward Looking Infrared (FLIR) camera
mounted on the underside of a helicopter at a flying height of 2,300 feet above ground level. To
maximize thermal contrast, the Thermal Infrared (TIR ) sensor was flown during early morning
when solar loading was minimized. Susitna River temperature recorders were used for
calibrating and verifying the thermal accuracy of the TIR imagery (URS 2013). On October 23,
24, 2013 and October 31, 2013, all ten Focus Areas and nine aquatic areas of interest in the
Middle River Segment were resurveyed at a higher resolution than was collected in 2012 (1.6
foot image resolution versus 2.3-foot resolution). For the groundwater analysis, the 2012 and
2013 TIR study GIS file depicting increased groundwater activity was used (Figure 3-3). This
layer was developed by qualitatively inspecting the thermal images for groundwater presence or
absence based on water temperatures.
3 The Project River Mile (PRM) system for the Susitna River was developed to provide a consistent and accurate
method of referencing features along the Susitna River. During the 1980s, researchers often referenced features by
river mile without identifying the source map or reference system. If a feature is described by river mile or historic
river mile (RM), then the exact location of that feature has not been verified. The use of PRMs provides a common
reference system and ensures that the location of the feature can be verified. The PRM was constructed by
digitizing the wetted width centerline of the main channel from 2011 Matanuska-Susitna Borough digital
orthophotos. Project River Mile 0.0 was established as mean low water of the Susitna River confluence at Cook
Inlet. A centerline corresponding to the channel thalweg was digitized upstream to the river source at Susitna
Glacier using data collected as part of the 2012 flow routing transect measurements. The resultant line is an ArcGIS
route feature class in which linear referencing tools may be applied. The use of RM will continue when citing a
1980s study or where the location of the feature has not been verified. Features identified by PRM are associated
with an ArcGIS data layer and process, and signifies that the location has been verified and reproduced.
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3.3. Instream Flow Study - Vertical Hydraulic Gradient
The IFS Study 8.5 and its component study efforts presented methods (Study 8.5 SIR, Appendix
D: Habitat Suitability Criteria Development [R2 2015]) that provide quantitative indices of
existing aquatic habitats that enable a determination of Project effects. As part of this effort, site-
specific HSC were developed for various fish species and life stages for biologically relevant
time periods in an effort to predict fish habitat use. These criteria included field observations of
physical phenomena during summer and winter sampling events in 2013 and 2014 that included
data collection of aquatic habitat depth, velocity, substrate, water quality, groundwater influence,
and turbidity (R2 2015). Measurements identifying positive or negative intergravel flow, using a
mini-piezometer for detecting the presence of groundwater upwelling or downwelling (VHG),
were recorded. A detailed description of the 2013 VHG sampling methods is presented in Study
8.5 ISR Part A, Section 4.5.1.4 (R2 2014).
For this groundwater analysis, positive VHG measurements were selected from the HSC
database at utilization/fish observation locations and then buffered 5 feet to provide an estimate
of upwelling area. Vertical hydraulic gradient measurements collected along the sampling site
were delineated in the GIS using the survey site downstream and upstream limits GPS locations
and subsequently buffered the average survey transect width to produce an upwelling polygon
(Figure 3-4).
3.4. Historic Spawning Surveys and Upwelling
Historic studies conducted as part of the 1980s Su-Hydro investigations specifically targeted the
evaluation of SW/GW interactions and defining areas of groundwater upwelling. As noted in
R2’s (2013) 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. Seagren and Wilkey (1985) provided a summary of water temperature
and substrate data from salmon spawning and groundwater upwelling sites that had been
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collected in 1984 and 1985 in the Middle Susitna River. 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. For the groundwater analysis, the 1980s data were
reviewed, with some selected for cross-comparison in a GIS map environment with more
contemporary information. Specifically, upwelling and/or bank seepage locations mapped in
Estes and Schmidt (1983, Appendix F) and Seagren and Wilkey (1985) were entered into the
GIS as point locations and buffered 5 feet to create a general area of groundwater activity (Figure
3-5).
3.5. Data Analysis and Map Generation
To spatially summarize and map areas of potential groundwater influence, the following polygon
features described in the methods section above were integrated using GIS merging software
tools:
• Ice Processes Study: 2012-2013 Thermal Open Lead Aerial Observation Surveys (HDR
2013)
• Ice Processes Study: 1983 Thermal Open Lead Mapping from Literature Review (HDR
2013)
• Water Quality Study: 2012-2013 Thermal Infrared Imagery Aerial Surveys (URS 2013)
• Instream Flow Study: 2013-2014 HSC Vertical Hydraulic Gradient Ground Surveys (R2
2015)
• Instream Flow Study: 1982 and 1984 Upwelling and Bank Seepage Mapping from Fish
Spawner Ground Surveys (Estes and Schmidt 1983, Appendix F)
Overlapping survey data were removed by aggregating features with groundwater activity
present to provide a single polygon representation at all such locations. Figure 3-6 provides an
example of this data processing step in slough and main channel habitats where delineations of
groundwater influence based on the different source documents and field data were simplified.
The next GIS processing step was a spatial overlay of Project River Mile and geomorphic reach
GIS layers to obtain a variety of summary statistics (Table 3-1), longitudinal profiles (Figure 3-7
and Figure 3-8), and maps (Appendix A) of the Middle River Segment.
4. RESULTS
The results of this analysis, i.e., broad-scale mapping of potential groundwater influenced areas
in the Middle River Segment of the Susitna River, are summarized by geomorphic reach in Table
3-1 and displayed in a 36-page, 11”x17”, 1:10,000 scale mapbook presented as Appendix A to
this TM. The majority of groundwater areas are found in geomorphic reach MR-6 (PRM 148.4-
122.7) and MR-7 (PRM 122.7-107.8), approximately 70 percent and 20 percent respectively
(Table 3-1). The areas are primarily found in off-channel and tributary habitats (Appendix A,
Map 16-34).
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The longitudinal profile of the Middle River Segment in Figure 3-7 shows that the distribution of
potential groundwater areas are cumulatively increasing between PRM 100 and PRM 128 at a
constant slope. After PRM 128 near the downstream end of FA-128 (Slough 8A), the increase in
area is more rapid until it plateaus near PRM 146 just upstream of FA-144 (Slough 21). Only
about 7 percent of the mapped Middle River Segment groundwater influenced areas are found
between PRM 146 and the proposed dam site (PRM 187.1). Figure 3-8 displays peaks where
groundwater areas are more prolific than locations immediately upstream or downstream. Such
locations include PRM 106 (FA-104 [Whiskers Creek]), PRM 113 (Slough 6), PRM 118 (Slough
8 and Lane Creek), PRM 126 (Moose Slough, Slough 8B, Slough 8C), PRM 130 (Slough 8A),
PRM 135 (Fourth of July Creek and adjacent side channel habitat), PRM 140 (FA-128 [Slough
11]), and PRM 145 (FA-144 [Slough 21]). This again highlights the relationship between
groundwater influenced areas and slough habitats.
5. DISCUSSION AND CONCLUSIONS
This analysis provides an example of how quantitative and qualitative aerial and ground field
efforts from multiple resource studies can be used for distinguishing potential groundwater
sources. The resultant set of GIS derived maps and spatially enabled data (Appendix A) are
useful products for identifying areas that are likely influenced by groundwater and provide a tool
for validating multi-disciplinary Focus Area model results and subsequent Middle River
Segment expansion.
Current Groundwater Study (Section 7.5) modeling efforts have looked at the response in
groundwater elevation during changes in the Susitna River mainstem stage during the winter
melt out period (June and July). Both correlation and Root Mean Square Error (RMSE) (a proxy
for the absolute difference in elevation profiles) have been analyzed. Most groundwater
elevations in FA-128 (Slough 8A) wells that are situated in a side slough and on a vegetated
island are highly correlated and most have low RMSE. By contrast, in FA-115 (Slough 6A)
correlation is weaker and RMSE is greater. Correspondence in stage and groundwater elevation
changes completely breaks down in wells furthest upland and away from the main channel. This
suggests that it may be possible to develop a categorization for influence on groundwater by the
Susitna River mainstem. The categorization or differentiation of groundwater types into three
categories – riverine dominated; transitional; and upland dominated will be completed for and
reported in the Updated Study Report (USR). These categories are consistent with those
described in SIR Study 7.5, Section 4.4.
Another recent groundwater modeling effort provided potentially valid expansion/extrapolation
areas for FA-128 (Slough 8A) groundwater processes where observed temperatures greater than
0.85° Celsius were indicative of nearby upwelling model grid cells. Thermal Infrared imagery
temperatures greater than 0.85° Celsius (274° Kelvin) could be selected from the geo-rectified
thermal images in valid extrapolation areas to quantify potential groundwater activity.
Groundwater modeling in Focus Areas beyond FA-128 (Slough 8A) will be completed for the
USR enabling this upscaling of Focus Area groundwater processes.
Although the upwelling broad-scale mapping effort has been completed, there are multiple
activities remaining for the USR that need to be completed before final groundwater influenced
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areas (categorized by dependencies on river, upland groundwater, or mixed river/groundwater)
within the entire Middle River Segment of the river can be developed. These include the
following:
• Selection and agreement on all upwelling indicator variables and spatial representations;
• Finalization of Focus Area groundwater analysis to allow Middle River Segment
upscaling; and
• Finalization of Focus Area groundwater models for categorization of groundwater types.
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6. REFERENCES CITED
Alaska Energy Authority (AEA). 2012. Revised Study Plan. Susitna-Watana Hydroelectric
Project, FERC Project No. 14241 Submittal: December 14, 2012. http://www.susitna-
watanahydro.org/study-plan.
Beaver, D.W. 1984. Slough Discharge Regression Equations. Memorandum to E.J.
Gemperline. Susitna Hydroelectric Project. Document No. 2372.
Dugan, L. J., D. A. Sterritt, and M. E. Stratton. 1984. The distribution and relative abundance of
juvenile salmon in the Susitna River drainage. Pages 75-131 in Schmidt, D.C., S.S. Hale,
D.L. Crawford, and P.M. Suchanek, eds., Resident and juvenile anadromous fish
investigations (May-October 1983). Report No. 2, Alaska Department of Fish and Game
Susitna Hydro Aquatic Studies. Prepared for Alaska Power Authority, Anchorage, Alaska.
APA Document No. 1784.
Durst, J.D. 2000. Fish Use of Upwellings: An Annotated Bibliography. Compiled for the
Region III Forest Practices Riparian Management Committee, Alaska Department of Fish
and Game. Habitat Restoration Division. http://forestry.alaska.gov/pdfs/6LitFish-
Upwellings8-11.pdf.
Estes, C., and D. Schmidt. 1983. Susitna Hydro Aquatic Studies Phase II Basic Data Report;
Volume 4: Aquatic Habitat and Instream Flow Studies, 1982; Appendix F: Habitat Location
Description and Photos. Prepared by Alaska Department of Fish and Game, Susitna Hydro
Aquatic Studies for the Alaska Power Authority. 470 pp. APA Document 587.
http://www.arlis.org/docs/vol1/Susitna/5/APA587.pdf.
HDR Alaska, Inc. (HDR). 2013. Susitna River Ice Processes Study Report. Susitna-Watana
Hydroelectric Project, FERC Project No. 14241 Submittal: March 7, 2013.
http://www.susitna-watanahydro.org/wp-content/uploads/2013/03/SuWa-2012Ice-Study-
Report-012012.v1.pdf.
HDR Alaska, Inc. (HDR). 2015. Ice Processes in the Susitna River Study. Susitna-Watana
Hydroelectric Project, FERC No. P-14241 Submittal: November 9, 2015, 2014-2015 Study
Implementation Report, Study 7.6. Prepared for Alaska Energy Authority, Anchorage,
Alaska. http://www.susitna-watanahydro.org/wp-
content/uploads/2015/11/07.6_ICE_SIR.pdf.
R2 Resource Consultants (R2). 2013. Summary Review of Susitna River Aquatic and Instream
Flow Studies Conducted in the 1980s with Relevance to Proposed Susitna – Watana Dam
Project – 2012: A Compendium of Technical Memoranda. Susitna-Watana Hydroelectric
Project, FERC No. P-14241 Submittal: March 25, 2013, Appendix F, Study 8.5 Technical
Memoranda. Prepared for Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/wp-
content/uploads/2013/03/SuWa_R2_Compendium_TechMemos.pdf and http://www.susitna-
watanahydro.org/wp-content/uploads/2013/10/SuWa_R2_Compendium_TechMemos-
Appendix3.pdf.
UPWELLING BROAD-SCALE MAPPING OF THE MIDDLE SUSITNA RIVER GROUNDWATER STUDY (7.5)
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FERC Project No. 14241 Page 11 October 2016
R2 Resource Consultants (R2). 2014. Fish and Aquatics Instream Flow Study 8.5 Initial Study
Report Part A (Sections 1-6, 8-10). Susitna-Watana Hydroelectric Project, FERC No. P-
14241 Submittal: June 3, 2014, Initial Study Report, Study 8.5. Prepared for Alaska Energy
Authority, Anchorage, Alaska. http://www.susitna-watanahydro.org/wp-
content/uploads/2014/05/08.5_IFS_ISR_PartA_1_of_5.pdf.
R2 Resource Consultants (R2). 2015. Habitat Suitability Criteria Development. Susitna-
Watana Hydroelectric Project, FERC No. P-14241 Submittal: November 9, 2015, 2014-2015
Study Implementation Report, Study 8.5, Appendix D. Prepared for Alaska Energy
Authority, Anchorage, Alaska. http://www.susitna-watanahydro.org/wp-
content/uploads/2015/11/08.5_IFS_SIR_App_D_HSC.pdf.
R&M Consultants, Inc. (R&M). 1985. Water Balance Studies of Middle Susitna Sloughs, Final
Report. Prepared under contract with Harza-Ebasco Susitna Joint Venture for the Alaska
Power Authority June. APA Document No. 2745. June 1985.
http://www.arlis.org/docs/vol2/hydropower/APA_DOC_no._2745.pdf.
Schoch, G.C. 1984. Susitna River Ice Study 1982-1983. Susitna Hydroelectric Project, FERC
Project No. 7114. Prepared by R&M Consultants, Inc. on behalf of Harza/Ebasco Joint
Venture for Alaska Power Authority, Anchorage, Alaska.
http://www.arlis.org/docs/vol2/hydropower/APA472.pdf.
Seagren, D.R, and R.G. Wilkey. 1985. Summary of Water Temperature and Substrate Data
from Selected Salmon Spawning and Groundwater Upwelling Sites in the Middle Susitna
River, Technical Data Report No. 12. Alaska Department of Fish and Game, Susitna River
Aquatic Studies Program. December 1985.
http://www.arlis.org/docs/vol1/Susitna/29/APA2913.pdf.
Trihey, W.E. 1982. 1982 Winter Temperature Study, Open File Report. Prepared for Acres
American, Inc. SUS Document No. 158. June 1982.
http://www.arlis.org/docs/vol1/Susitna/SUS/1/SUS158.pdf.
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 No. 2658.
URS Corporation (URS). 2013. Thermal Infrared Remote Sensing Pilot Study. Susitna-Watana
Hydroelectric Project, FERC Project No. 14241 Submittal: March 7, 2013.
http://www.susitna-watanahydro.org/wp-content/uploads/2013/03/SuWa-2012-study-report-
TIR.pdf.
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7. TABLES
Table 3-1. Summary of potential groundwater influenced areas by geomorphic reach in the Susitna Middle River
Segment.
Geomorphic Reach Acres
Reach Breaks
( PRM / RM )1 Slope
(ft/mi) 1 Lateral Constraints1 Upstream Downstream
MR-1 0.4 187.1 / 184.3 184.6 / 181.9 9.2 Tertiary-Cretaceous Gneiss
MR-2 6.8 184.6 / 181.9 169.6 / 166.4 10.8 Cretaceous Kahiltna Flysch Tertiary-
Cretaceous Gneiss
MR-3 0.7 169.6 / 166.4 166.1 / 163.0 12.3 Paleocene Granites
MR-4 3.3 166.1 / 163.0 153.9 / 150.3 30.6 Paleocene Granites
MR-5 2.6 153.9 / 150.3 148.4 / 144.9 12.3 Cretaceous Kahiltna Flysch
MR-6 492.9 148.4 / 144.9 122.7 / 118.9 10.7
Cretaceous Kahiltna Flysch with
undifferentiated Upper Pleistocene moraines,
kames, lacustrine deposits
MR-7 151.7 122.7 / 118.9 107.8 / 104.1 8.3
Cretaceous Kahiltna Flysch with
undifferentiated Upper Pleistocene moraines,
kames, lacustrine deposits
MR-8 55.0 107.8 / 104.1 102.4 / 98.6 8.8 Upper Pleistocene moraines, outwash and
Holocene Alluvial Terrace deposits
Notes:
1Information from Table 5.2-1 in Study 6.5 SIR, Attachment 1: Geomorphic Reach Delineation and Characterization, Upper,
Middle and Lower Susitna River Segments – 2015 Update Technical Memorandum
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8. FIGURES
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Figure 3-1. Example GIS process of converting 2012 Ice Study thermal open lead lines and points to buffered areas in
Upper Side Channel 11 and Slough 11, FA- 138 (Gold Creek).
Figure 3-2. Example GIS process of converting 1983 thermal open ice lead observation points to buffered areas in Slough
8A and main channel habitat at PRM 128.6, FA-128 (Slough 8A).
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Figure 3-3. Example GIS process of converting 2012 thermal infrared imagery to increased groundwater activity areas in
Unnamed Tributary 117.4, Slough 8, Lane Creek, and main channel habitat between PRM 117 and 118.8.
Figure 3-4. Example GIS process of converting 2013-2014 Instream Flow Study HSC vertical hydraulic gradient sample
locations (points) and sample sites (lines) to buffered areas in Side Channel 21, FA-144 (Slough 21).
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Figure 3-5. Example GIS process of converting 1982 open-water upwelling locations to buffered areas in Slough 9 and
Slough 9B, PRM 131.6 to PRM 132.6.
Figure 3-6. Example GIS process of aggregating overlapping survey data to a single groundwater activity polygon in
Slough 19, Slough 20, and mainstem habitat from PRM 143.2 to PRM 143.5 at the upstream end of FA-141 (Indian
River).
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Figure 3-7. Longitudinal distribution of potential groundwater influenced areas in the Middle River Segment of the
Susitna River. See Appendix A for GIS delineations of specific groundwater areas.
Figure 3-8. Cumulative and Project River Mile based longitudinal distribution of potential groundwater influenced areas
in the Middle River Segment of the Susitna River. See Appendix A for GIS delineations of specific groundwater areas.
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APPENDIX A: LOCATIONS OF POTENTIAL GROUNDWATER
INFLUENCED AREAS WITHIN THE MIDDLE SUSITNA RIVER