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Susitna-Watana Hydroelectric Project Document
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Title:
Water quality modeling study, Study plan Section 5.6 : Initial study report --
Part A: Sections 1-6, 8-10 SuWa 223
Author(s) – Personal:
Author(s) – Corporate:
URS/Tetra Tech, Inc.
AEA-identified category, if specified:
Initial study report
AEA-identified series, if specified:
Series (ARLIS-assigned report number):
Susitna-Watana Hydroelectric Project document number 223
Existing numbers on document:
Published by:
[Anchorage : Alaska Energy Authority, 2014]
Date published:
June 2014
Published for:
Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers: Final or Draft status, as indicated:
Document type:
Pagination:
iii, 20 p.
Related work(s):
The following parts of Section 5.6 appear in separate files: Part
A ; Part B ; Part C.
Pages added/changed by ARLIS:
Notes:
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Water Quality Modeling Study
Study Plan Section 5.6
Initial Study Report
Part A: Sections 1-6, 8-10
Prepared for
Alaska Energy Authority
Prepared by
URS/Tetra Tech, Inc.
June 2014
INITIAL STUDY REPORT WATER QUALITY MODELING STUDY (5.6)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Part A - Page i June 2014
TABLE OF CONTENTS
1. Introduction ....................................................................................................................... 1
2. Study Objectives................................................................................................................ 1
3. Study Area ......................................................................................................................... 2
4. Methods .............................................................................................................................. 2
4.1. Model Description .................................................................................................. 2
4.2. Reservoir and Downstream River Modeling Approaches ...................................... 3
4.3. Focus Area Modeling .............................................................................................. 5
4.4. Scales for Modeling and Resolution of the Output ................................................. 5
4.5. Variances................................................................................................................. 6
5. Results ................................................................................................................................ 6
5.1. Selection of Model State Variables and Options .................................................... 6
5.2. Reservoir Model Configuration and Preliminary Results ....................................... 7
5.3. River Model Configuration and Preliminary Results ............................................. 8
5.4. Focus Area Modeling .............................................................................................. 8
6. Discussion........................................................................................................................... 8
7. Completing the Study ....................................................................................................... 9
8. Literature Cited ................................................................................................................ 9
9. Tables ............................................................................................................................... 11
10. Figures .............................................................................................................................. 15
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LIST OF TABLES
Table 3-1. Susitna River Basin Temperature and Water Quality Monitoring Sites .................... 11
Table 4.1-1. Evaluation of Models based on Technical, Regulatory, and Management Criteria 13
LIST OF FIGURES
Figure 3-1. Stream Water Quality and Temperature Data Collection Sites for the
Susitna-Watana Hydroelectric Project ................................................................................... 16
Figure 5.2-1. Reservoir Model Grid with Bathymetry ................................................................ 17
Figure 5.3-1. River Model Grid Below Dam Site (PRM 187.2) ................................................. 18
Figure 5.3-2. River Model Grid Upstream of PRM 80. ............................................................... 19
Figure 5.4-1. Enhanced River Model Grid for Focus Area FA-115 ............................................ 20
INITIAL STUDY REPORT WATER QUALITY MODELING STUDY (5.6)
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FERC Project No. 14241 Part A - Page iii June 2014
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
1-D one-dimensional
2-D two-dimensional
3-D three-dimensional
AEA Alaska Energy Authority
AEIDC Arctic Environmental Information and Data Center
EFDC Environmental Fluid Dynamics Code
FA Focus Area
FERC Federal Energy Regulatory Commission
Hg mercury
ILP Integrated Licensing Process
ISR Initial Study Report
PRM Project River Mile
Project Susitna-Watana Hydroelectric Project
RM River Mile(s) referencing those of the 1980s Alaska Power Authority Project.
RSP Revised Study Plan
SPD study plan determination
TSS total suspended solids
WOE weight of evidence
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FERC Project No. 14241 Part A - Page 1 June 2014
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, which included 58 individual study plans (AEA
2012). Included within the RSP was the Water Quality Modeling Study, Section 5.6. RSP
Section 5.6 focuses on the modeling planned for assessing the effects of the proposed Susitna-
Watana Project (Project) and its operations on water quality in the Susitna River basin.
On February 1, 2013, FERC staff issued its study determination (February 1 SPD) for 44 of the
58 studies, approving 31 studies as filed and 13 with modifications. On April 1, 2013 FERC
issued its study determination (April 1 SPD) for the remaining 14 studies; approving 1 study as
filed and 13 with modifications. RSP Section 5.6 was one of the 13 approved with
modifications. In its April 1 SPD, FERC recommended the following:
Calibration of the Hydrodynamic Model Component of EFDC [Environmental Fluid
Dynamics Code]
- We recommend that AEA incorporate water-surface elevations and flow velocities
when calibrating the hydrodynamic model and that the hydrodynamic model be
calibrated prior to the calibration of the water quality model component of the EFDC
model.
AEA included FERC’s requested modification in the Final Study Plan.
Following the first study season, FERC’s regulations for the Integrated Licensing Process (ILP)
require AEA to “prepare and file with the Commission an initial study report describing its
overall progress in implementing the study plan and schedule and the data collected, including an
explanation of any variance from the study plan and schedule” (18 CFR 5.15(c)(1)). This Initial
Study Report (ISR) on Water Quality Modeling Study has been prepared in accordance with
FERC’s ILP regulations and details AEA’s status in implementing the study, as set forth in the
FERC-approved RSP and as modified by FERC’s April 1 SPD, as appropriate (collectively
referred to herein as the “Study Plan”).
2. STUDY OBJECTIVES
The collective goal of the water quality studies (Baseline Water Quality Study, Water Quality
Modeling Study, and the Mercury Assessment and Potential for Bioaccumulation Study) is to
assess the impacts of the proposed Project operations on water quality in the Susitna River basin
with particular reference to state water quality standards. Predicting the potential impacts of the
dam and its proposed operations on water quality requires the development of a water quality
model. The goal of the Water Quality Modeling Study is to utilize the extensive information
collected from the Baseline Water Quality Study to develop a model(s) that evaluates the
potential impacts of the proposed Project and operations on various physical parameters within
the Susitna River watershed.
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The objectives of the Water Quality Modeling Study are as follows:
• Implement (with input from licensing participants) an appropriate reservoir and river
water temperature model for use with past and current monitoring data.
• Using the data developed as part of the Baseline Water Quality Study, model water
quality conditions in the proposed Watana Reservoir, including (but not necessarily
limited to) temperature, DO, fine suspended sediment and turbidity, chlorophyll-a,
nutrients, ice, and metals.
• Model water quality conditions in the Susitna River from the proposed site of the Watana
Dam downstream, including (but not necessarily limited to) temperature, DO, fine
suspended sediment and turbidity, chlorophyll-a, and nutrients. Ice processes effects are
accounted for using output from the River 1D Ice Processes Model (in coordination with
the Ice Processes Study).
3. STUDY AREA
As established in RSP Section 5.6.3, the study area begins at RM 15.1 (PRM 19.9) and extends
past the proposed dam site to RM 233.4 (PRM 235.2) as described in Table 3-1. The distribution
of sites for the Susitna Basin is also shown in Figure 3-1.
4. METHODS
4.1. Model Description
During 2013, AEA selected a (3-D) Reservoir Water Quality Model, a (2-D) River Water
Quality Model, and a (2-D) River Water Quality Model with Enhanced Resolution Focus Areas
for this Project. The rationale for selection of the (3-D and 2-D) Reservoir and River Water
Quality Models is set forth in the Technical Memorandum: Water Quality Modeling Study:
Model Selection (May 18, 2012).
The models are capable of simulating both river and reservoir environments. It is a multi-
dimensional dynamic model that includes hydrodynamics, water temperature, water quality, and
sediment transport modules and considers ice formation and break-up.
Ice formation and break-up can impact hydrodynamics and water quality conditions in the
reservoir and riverine sections of the basin. Ice cover affects transfer of oxygen to and from the
atmosphere and this directly affects the DO concentration in the water column. Ice dynamics
evaluated in the Ice Processes Study were used to inform the water quality model of ice cover
and thickness and the output.
The model was configured for the reservoir and downstream river under pre-and post-Project
conditions. The upstream boundary conditions for the pre-Project river model were provided by
observational data at or near the dam. The reservoir model provided upstream boundary
conditions of the post-Project version of the river model. This approach forms a holistic
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modeling framework that can accurately simulate changes in the hydrodynamic, temperature,
and water quality regime within the reservoir and downstream river. The modesl for use in this
study features an advanced turbulence closure scheme to represent vertical mixing in reservoirs,
necessary to predict future conditions. Thus, it is capable of representing the temperature regime
within the reservoir without resorting to arbitrary assumptions about vertical mixing coefficients.
The models selected for this proposed Project have the ability to simulate an entire suite of water
quality parameters, and is internally coupled with the hydrodynamic and temperature modeling
processes. The model was configured to simulate the impact of the proposed Project on
temperature as well as DO, nutrients, algae, turbidity, total suspended solids (TSS), and other
key water quality features both within the reservoir and for the downstream river (Table 4.1-1).
This avoids the added complexity associated with transferring information among multiple
models and increases the efficiency of model application.
4.2. Reservoir and Downstream River Modeling Approaches
The reservoir model represents the river from the proposed dam location to the upstream extent
of inundation. The model will represent the proposed reservoir condition when the dam is in
place. The reservoir representation is being developed based on the local bathymetry and
dimensions of the proposed dam. A three-dimensional model (3-D) Reservoir Water Quality
Model is being developed for the proposed reservoir to represent the spatial variability in
hydrodynamics and water quality in longitudinal, vertical, and lateral directions. The model will
simulate flow or circulation in the reservoir, turbulence mixing, temperature dynamics, nutrient
fate and transport, interaction between nutrients and algae, sediment transport, and metals
transport. The key feature to be captured is water column stratification during the warm season
and the de-stratification when air temperatures cool down. The capability of predictively
representing the stratification/de-stratification period is of critical importance for evaluating the
impact of the dam because this is the critical period for primary production and nutrient cycling
in the reservoir.
With the dam in place, the original river will be converted into a slow flowing reservoir;
therefore, any sediment previously mobilized will likely settle in the reservoir, disrupting the
natural sediment transport processes. Before the construction of the dam, primary production is
likely driven by periphyton. After construction of the dam, periphyton will be largely driven out
of existence due to deep water conditions typical of a reservoir environment. In lieu of
periphyton, phytoplankton will likely be the dominant source of primary production of the
ecological system with the dam in place. Nutrients from upstream will have longer retention in
the reservoir, providing nutrient sources to fuel phytoplankton growth. All processes are to be
predictively simulated by the reservoir model.
Because the dam is not in place when the model is constructed, proper calibration of the model
using actual reservoir data is not possible. To achieve reasonable predictions of water quality
conditions in the proposed reservoir, a literature survey was conducted to acquire
parameterization schemes of the model. An uncertainty analysis approach will also be developed
to account for the lack of data for calibration, therefore enhancing the reliability of reservoir
model predictions.
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Downstream of the proposed dam location, a river model is being developed to evaluate the
effects of the proposed Project. The same model platform used for the reservoir model is being
implemented for the river model maintaining consistency of state variables and process
representations. The (2-D) River Water Quality Model will be capable of representing
conditions in both the pre-Project absence and post-Project presence of the dam. The river model
will extend downstream from the dam site to the lowermost monitoring site on the Susitna River
mainstem (PRM 19.9) downstream of the Susitna-Talkeetna-Chulitna confluence. The (2-D)
River Water Quality Model uses channel topography and flow data at select locations will be
used for model configuration and calibration necessary for predicting water quality conditions
under various Project operational scenarios.
Flow, temperature, TSS, DO, nutrients, turbidity (continuous at USGS sites and bi-weekly at
additional locations required for calibrating the model), and chlorophyll-a output from the (3D)
Reservoir Water Quality Model is being directly input into the downstream post-Project version
of the (2-D) River Water Quality Model. This will enable downstream evaluation of potential
impacts of the proposed Project on hydrodynamic, temperature, and water quality conditions.
Observational data will provide the upstream boundary conditions for the pre-Project version of
the river model.
The (2-D) River Water Quality Model will be calibrated and validated using available data
concurrently with the initial reservoir condition model (representing absence of the dam). Output
from the models will be used directly in other studies (e.g., Ice Processes, Productivity, and
Instream Flow studies).
To meet the Study Plan objectives, the pre-project river upstream of the dam site will be modeled
using imagery shorelines, estimated bed elevations, and rectangular cross-sections. Resolution of
the pre-project model is determined by uniformity in water quality conditions from the
uppermost site to the site immediately below the dam. AEA reported existing water quality as
well-mixed surface water conditions (ISR Section 5.5; Sections 5.2 and 5.4.2) and a single river
channel that has little to no braiding in the Upper River pre-project conditions. RSP Section
5.6.4.8.2 described the type of model output under conditions when water quality uniformity was
high at depth and laterally within the non-braided channel.
The (2-D) River Water Quality Model will be calibrated in order to simulate water quality
conditions for load-following analysis. When calibrating the (2-D) River Water Quality Model,
water-surface elevations and flow velocities are incorporated. The hydrodynamic module in the
(2-D) River Water Quality Model is being calibrated prior to calibration of the water quality
module. Organic carbon content from inflow sources will be correlated with mercury
concentrations determined from the Baseline Water Quality Study discussed in Section 5.5 of the
RSP. Predicted water quality conditions established by Project operations and that promote
methylation of mercury in the bioaccumulative form will be identified by location and intensity
in both riverine and reservoir habitats. Water temperature modeling and routing of fluctuating
flows immediately prior to and during ice cover development may be conducted with a separate
thermodynamics-based River 1-D ice-processes model: the Susitna Hydraulic and Thermal
Processes Model (Section 7.6.3.2).
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Modeling of mercury concentrations in dissolved and in methylated form will be done by
updating the (3-D) Reservoir Water Quality Model to simulate three sorptive toxic variables
representing mercury (Hg) states. Algorithms have been successfully used with the (3-D)
Reservoir Water Quality Model in other studies and will be modified to account for potential
sources of Hg as the reservoir is filled (e.g., soils, vegetation, air deposition). Other metals
parameters will be modeled if significant concentrations are identified from surface water and
sediment. However, cumulative impacts of multiple metals on aquatic life are difficult to predict
using the proposed modeling strategy because there are associated uncertainties. Measuring
additivity or synergism of toxics effects is possible using laboratory bioassays, but may not be
adequately predicted by a model. The level of uncertainty in extrapolating results from
laboratory to field conditions is large and potentially unreliable. A suggested approach for
estimating toxicity mixtures would be to develop a weight of evidence (WOE) algorithm that
produces a weighting factor for re-calculating the potential chronic and acute toxic effects of a
mixture (Mumtaz et al. 1998).
4.3. Focus Area Modeling
The (2-D) River Water Quality Model with Enhanced Resolution Focus Areas will be used to
predict water quality conditions at a finer scale of resolution for river Focus Areas. The increased
intensity of sampling at transects 100 m apart and at three locations across each transect will
improve resolution for predictions at approximately 100 m longitudinally and a smaller distance
laterally. These models are embedded within the larger-scale (2-D) River Water Quality Model
used for the entire riverine component of the Project area. An embedded model can also be used
for predicting conditions in sloughs and selected braided areas of the mainstem Susitna River.
Some of the water quality parameters listed in Section 5.5.4.4 of the RSP will be used to predict
conditions within the Focus Areas to determine if suitability of habitat for life stages of select
fish species is maintained or changes under each of the operational scenarios. The resolution of
the (2-D) River Water Quality Model with Enhanced Resolution Focus Areas will be dynamic,
allowing both the temporal and areal extent of the water quality parameter variations associated
with various load-following scenarios to be determined.
4.4. Scales for Modeling and Resolution of the Output
The large-scale (2-D) River Water Quality Model calibrated using the mainstem water quality
monitoring data will have a longitudinal predictive resolution between 250 m and 1 kilometer
(km) depending on channel complexity, lateral variability of conditions, and required run-time
performance. Single channel areas of the mainstem Susitna River and sloughs may not require
higher resolution predictions if water quality conditions are uniform. The uniformity of
conditions will be evaluated by measuring across transects at a few locations in the drainage to
determine if lateral variability is low.
Model grid size determines spatial resolution of predicted water quality conditions. The reservoir
and riverine areas of the Project are represented by model grid cells and model predicted water
quality conditions represent averages over the cells. The grid size is dependent on a number of
characteristics of the Project area. These characteristics include elevation changes throughout the
model domain, surrounding terrain, and length of time the model is run for predicting temporal
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changes. Each of the factors ultimately determines the resolution of the predictive capability of
the EFDC model.
4.5. Variances
No variances from the methods occurred during the implementation of this study in 2013.
5. RESULTS
5.1. Selection of Model State Variables and Options
State variables for the hydrodynamic components of the reservoir and river models include water
surface elevation, horizontal velocity, and vertical velocity for the reservoir model. The three-
dimension reservoir model uses a curvilinear horizontal grid and the (3-D) Reservoir Water
Quality Model’s generalized vertical coordinate formulation, which is appropriate for deep and
narrow reservoirs. The two-dimension river model uses a curvilinear horizontal grid. Both the
reservoir and river models operate in drying and wetting mode to accommodate large pool
fluctuations in the reservoir and floodplain inundation in the river under high flow conditions.
The full (3D and 2D) Reservoir and River Water Quality Model thermal formulation is being
used for temperature simulation, which includes incoming short wave radiation, long-wave
radiated, and sensible and latent surface heat exchange. A bed thermal model is also coupled to
the reservoir water column thermal formulation. Horizontally variable ice cover and thickness
will be simulated by the reservoir temperature model. Ice cover and thickness will not be
directly simulated in the river but will be provided by the River Ice Processes model (RSP
Section 7.6). The provided information will be used to account for ice effects on surface re-
aeration and light penetration.
The reservoir and river models will simulate fine inorganic sediment having particle diameters
less than 125 microns. This serves a number of purposes including incorporation of inorganic
suspended sediment, concentration on light attenuation, and estimating the trapping of fine
sediment by the reservoir. Sediment loadings at the dam site and at the upstream extent of the
reservoir will be provided by the Geomorphology Modeling Study (RSP Section 6.6). Existing
fine sediment processes formulations for settling, deposition and mobilization in the (3-D)
Reservoir Water Quality Model are being used.
The water quality models will use a reduced set of the full set of state variables. The current set
under consideration includes:
• Two phytoplankton species
• Periphyton
• Dissolved oxygen
• Dissolved and particulate organic carbon
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• Dissolved and particulate organic nitrogen
• Nitrite plus Nitrate
• Ammonia Nitrogen
• Dissolved and particulate organic phosphorous
• Dissolved and particulate inorganic phosphorous
These categories of parameters represent 14 state variables. The standard set of sediment
organic and nutrient variables in the diagenesis module will be used. Reaction rates and
particulate settling velocity will be based on analysis of observational data and literature values
for high latitude reservoirs and rivers.
The (3-D) Reservoir Water Quality Model toxic contaminant sub-model will be used to simulate
mercury cycling and possibly other metal and organic contaminants if analysis of observational
data suggests a need to address potential toxicity. The mercury model will simulate elemental,
ionic, and methyl mercury in the water column and sediment bed. Free dissolved, dissolved
organic carbon, complexated and particulate phases, are simulated. Dissolved and particulate
organic carbon concentrations will be provided by the water quality model and fine inorganic
sediment concentrations will be provided by the sediment transport model component.
5.2. Reservoir Model Configuration and Preliminary Results
The reservoir model has been spatially configured with approximately 1400 horizontal grid cells
and 20 vertical layers. Longitudinal horizontal resolution along the drowned river valley ranges
from 400 to 800 meters with lateral resolution ranging from 75 to 150 meters. The reservoir
model horizontal grid is shown in Figure 5.2-1. Vertical resolution with 20 layers ranges from
2.5 meters layer thickness near the surface to 25 meter thickness near bottom of the deepest area.
The number of layers varies horizontally to account for topographic variations. A higher
resolution 40 layer vertical grid is also being used to investigate the sensitivity of predicted
temperature stratification to vertical resolution. Topographic layer used to configure the model is
based on the MatSu Lidar DEM. Figure 5.2-1 shows the horizontal reservoir grid and
bathymetry.
The reservoir hydrodynamic model has been tested using the 1984 historical inflow and a
corresponding load following outflow. The model successfully simulated the one year period
which has an approximately 45 meter variation in pool level. Scaling of computational
performance for this simulation indicated that approximately four years can be simulated in one
day. Preliminary temperature simulation for ice-free conditions indicated that the 20 layer
configuration adequately represents vertical stratification. Annual time scale temperature
simulations are being conducted to evaluate a number of ice processes representations ranging
from semi-empirical freezing degree day to thermodynamic cover and thickness without and
with transport of ice cover. Inclusion of frazil ice remains a possible option.
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5.3. River Model Configuration and Preliminary Results
The river model was initially configured spatially between PRM 80 and PRM 187.2 with
approximately 1000 horizontal grid cells. Longitudinal resolution is approximately 500 meter
and lateral resolution uses three cells laterally in the main channel and one cell laterally in
smaller side channels. Channel bathymetry is based on 88 cross sections surveyed in 2012.
Figures 5.3-1 and 5.3-2 show model grids below the dam site and upstream of PRM 80. This
configuration is being extended downstream to PRM 30 using additional cross sections surveyed
during 2013 and higher resolution surveys in a number of Focus Areas. Lateral resolution is
being refined to better represent side channels and sloughs.
The river hydrodynamic model has been tested using the 1984 historical flow and the 1984 load
following flow from the reservoir without accounting for ice cover. Scaling of computational
performance for this simulation indicated that approximately six years can be simulated in one
day. The hydrodynamic model has also simulated the June through August 2012 period for
preliminary calibration. Preliminary temperature simulation of ice free conditions is in progress
for calibration. Ice covered hydrodynamic and temperature simulation will require information
from the ice processes model and proceed when those data become available.
5.4. Focus Area Modeling
The (2-D) River Water Quality Model with Enhanced Resolution Focus Areas is being locally
enhanced with finer spatial resolution to simulate water quality processes in the riverine focus
areas. Anticipated spatial resolution in the focus areas is approximately 100 m longitudinally
and 30 m laterally. Higher resolution bathymetric data are presently available for Focus Areas
FA-104 (Whiskers Slough), FA-113 (Oxbow 1), and FA-115 (Slough 6A). Figure 5.4-1 shows
the preliminary refined grid in Focus Area FA-115 (Slough 6A). The Focus Area grid
enhancements are being embedded in a version of the full river model to eliminate the need for
inefficient, limited area modeling. Additional Focus Areas are being added as corresponding
bathymetric data become available.
6. DISCUSSION
The reservoir and river EFDC models have been configured for hydrodynamics, temperature,
and fine suspended sediment. The models have been tested with annual time-scale historical and
proposed Project flow scenarios to demonstrate stability and acceptable run-time performance.
Test data sets for water temperature generated in 2012 have been used in both the reservoir and
riverine models and capable of decade time scale simulations. The same data set has been
extended into 2013 and used to verify and further refine calibration of the model. Development
of the model and calibration with water quality data is on schedule and will meet study
objectives.
The river model hydrodynamics are being calibrated to 2012 water surface elevation and velocity
observations. Model parameterization has been completed for both the large-scale riverine model
and the enhancement for the internally-coupled Focus Area riverine model. The riverine model
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has been configured with horizontal grid cells and tested using the 1984 load following flow
from the reservoir without accounting for ice cover.
Reservoir temperature simulations are being conducted to investigate seasonal thermal structure
including thermocline formation, fall overturn and ice cover formation to determine vertical
resolution sensitivity and refine the resolution for optimum model performance. The reservoir
model has been configured with both vertical and horizontal grid cells and the hydrodynamic
model tested using the 1984 historical inflow and a corresponding load following outflow.
River temperature simulations are being conducted for temperature calibration to ice-free post-
Project observational data. Output from the reservoir model will be provided for development of
the River1D Ice Processes Model (Study 7.6). Water quality monitoring data and watershed
characteristics are being analyzed to develop organic matter and nutrient loads necessary for
water quality model configuration.
Preliminary simulations of the transport of fine inorganic sediment (less than 125 microns)
through the reservoir and in the downstream river under pre- and post-Project conditions are
underway.
7. COMPLETING THE STUDY
[Section 7 appears in the Part C section of this ISR.]
8. LITERATURE CITED
AEA (Alaska Energy Authority). 2012. Revised Study Plan: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/study-plan.
AEIDC (Arctic Environmental Information and Data Center), 1983a. Examination of Susitna
River Discharge and Temperature Changes Due to the Proposed Susitna Hydroelectric
Project – Final Report. Prepared by Arctic Environmental Information and Data Center
Anchorage, AK. Submitted to Harza-Ebasco Susitna Joint Venture Anchorage, AK.
Prepared for the Alaska Power Authority, Anchorage, AK.
AEIDC. 1983b. Stream Flow and Temperature Modeling in the Susitna Basin, Alaska. Prepared
by Arctic Environmental Information and Data Center Anchorage, AK. Submitted to
Harza-Ebasco Susitna Joint Venture Anchorage, AK. Prepared for the Alaska Power
Authority, Anchorage, AK.
Borgmann, U., W. P. Norwood and D. G. Dixon. 2008. Modelling bioaccumulation and toxicity
of metal mixtures. Human and Ecological Risk Assessment: An International Journal
14(2): 266-289.
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Cole, T.M. and S. A. Wells. 2000. CE-QUAL-W2: A two-dimensional, laterally averaged,
Hydrodynamic and Water Quality Model, Version 3.0, Instruction Report EL-2000. US
Army Engineering and Research Development Center, Vicksburg, MS.
Hamrick, J.M. 1992. A Three-Dimensional Environmental Fluid Dynamics Computer Code:
Theoretical and Computational Aspects, Special Report 317. The College of William and
Mary, Virginia Institute of Marine Science. 63 pp.
Mumtaz, M.M., C.T. De Roza, J. Groten, V.J. Feron, H. Hansen, and P.R. Durkin. 1998.
Estimation of Toxicity of Chemical Mixtures through Modeling of Chemical Interactions.
Environmental Health Perspectives Volume 106: Supplement 6. 1353-1360.
Patterson, John, J. Imberger, B. Hebbert, and I. Loh. 1977. Users Guide to DYRESM – A
Simulation Model for Reservoirs of Medium Size. University of Western Australia,
Nedlands, Western Australia.
Tetra Tech, Inc. 2007a. The Environmental Fluid Dynamics Computer Code Theory and
Computation: Volume 1 Hydrodynamic and Mass Transport. Tetra Tech, Inc., Fairfax,
VA.61 pp.
Tetra Tech, Inc. 2007b. The Environmental Fluid Dynamics Computer Code Theory and
Computation: Volume 2 Sediment and Contaminant Transport and Fate. Tetra Tech,
Inc., Fairfax, VA.96 pp.
Tetra Tech. 2007c. The Environmental Fluid Dynamics Computer Code, Theory and
Computation: Volume 3: Water Quality and Eutrophication. Tetra Tech, Inc., Fairfax,
VA.
URS. 2011. AEA Susitna Water Quality and Sediment Transport Data Gap Analysis Report.
Prepared by Tetra Tech, URS, and Arctic Hydrologic Consultants. Anchorage, Alaska.
62p.+Appendixes.
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9. TABLES
Table 3-1. Susitna River Basin Temperature and Water Quality Monitoring Sites
Susitna Project
River Mile (PRM) Description Susitna River
Slough ID Latitude
(decimal degrees)
Longitude
(decimal degrees)
19.9 Susitna above
Alexander Creek NA 61.4014 -150.519
29.93 Susitna Station NA 61.5454 -150.516
32.5 Yentna River NA 61.589 -150.468
33.6 Susitna above Yentna NA 61.5752 -150.248
45.13 Deshka River NA 61.7098 -150.324
59.91 Susitna NA 61.8589 -150.18
87.83 Susitna at Parks
Highway East NA 62.175 -150.174
88.33 Susitna at Parks
Highway West NA 62.1765 -150.177
99.2 LRX 1 NA 62.3223 -150.127
102.8 Talkeetna River NA 62.3418 -150.106
118.6 Chulitna River NA 62.5574 -150.236
1072,3 Talkeetna NA 62.3943 -150.134
116.692 LRX 18 NA 62.5243 -150.112
124.22,3 Curry Fishwheel Camp NA 62.6178 -150.012
129.6 -- 8A 62.6707 -149.903
129.92 LRX 29 NA 62.6718 -149.902
132.73 -- 9 62.7022 -149.843
134.12 LRX 35 NA 62.714 -149.81
-- 11 62.7555 -149.7111
140.0 Susitna near Gold
Creek NA 62.7672 -149.694
140.13 Gold Creek NA 62.7676 -149.691
140.01 -- 16B 62.7812 -149.674
142.23 Indian River NA 62.8009 -149.664
142.32 Susitna above Indian
River NA 62.7857 -149.651
143.6 -- 19 62.7929 -149.615
143.62 LRX 53 NA 62.7948 -149.613
145.6 -- 21 62.8163 -149.576
152.2 Susitna below Portage
Creek NA 62.8316 -149.406
153.02 Susitna above Portage Creek NA 62.8286 -149.379
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Susitna Project River Mile (PRM) Description Susitna River Slough ID Latitude
(decimal degrees)
Longitude
(decimal degrees)
152.7 Portage Creek NA 62.8317 -149.379
168.11 Susitna NA 62.7899 -148.997
183.11 Susitna below Tsusena
Creek NA 62.8157 -148.652
184.83 Tsusena Creek NA 62.8224 -148.613
187.21 Susitna at Watana
Dam site NA 62.8226 -148.533
196.8 Watana Creek NA 62.8296 -148.259
209.2 Kosina Creek NA 62.7822 -147.94
225.53 Susitna near Cantwell NA 62.7052 147.538
235.2 Oshetna Creek NA 62.6402 -147.383
1. Site not sampled for water quality or temperature in the 1980s or location moved slightly from original location.
2. Proposed mainstem Susitna River temperature monitoring sites for purposes of 1980s SNTEMP model
evaluation.
3. Locations with overlap of water quality temperature monitoring sites with other studies.
Locations in bold font represent that both temperature and water quality samples are collected from a site.
INITIAL STUDY REPORT WATER QUALITY MODELING STUDY (5.6)
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FERC Project No. 14241 Part A - Page 13 June 2014
Table 4.1-1. Evaluation of Models based on Technical, Regulatory, and Management Criteria
High Suitability Medium Suitability Low Suitability
Considerations Relative Importance H2OBAL/SNTEMP/DYRESM CE QUAL W2 EFDC
Technical Criteria
Physical Processes:
• advection, dispersion High
• momentum High
• compatible with external ice
simulation models High
• reservoir operations High
• predictive temperature
simulation (high latitude
shading)
High
Water Quality:
• total nutrient concentrations High
• dissolved/particulate
partitioning Medium
• predictive sediment diagenesis Medium
• sediment transport High
• algae High
• dissolved oxygen High
• metals High
Temporal Scale and Representation:
• long term trends and averages Medium
• continuous – ability to predict
small time-step variability High
Spatial Scale and Representation:
• multi-dimensional
representation High
• grid complexity - allows
predictions at numerous
locations throughout model
domain
High
• suitability for local scale
analyses, including local
discharge evaluation
Medium
Regulatory Criteria
Enables comparison to AK criteria High
Flexibility for analysis of scenarios,
including climate change High
INITIAL STUDY REPORT WATER QUALITY MODELING STUDY (5.6)
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FERC Project No. 14241 Part A - Page 14 June 2014
High Suitability Medium Suitability Low Suitability
Considerations Relative Importance H2OBAL/SNTEMP/DYRESM CE QUAL W2 EFDC
Technically defensible (previous
use/validation, thoroughly tested, results
in peer-reviewed literature, TMDL
studies)
High
Management Criteria
Existing model availability High
Data needs High
Public domain (non-proprietary) High
Cost Medium
Time needed for application Medium N/A
Licensing participant community
familiarity Low
Level of expertise required Low
User interface Low
Model documentation Medium
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10. FIGURES
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Figure 3-1. Stream Water Quality and Temperature Data Collection Sites for the Susitna-Watana Hydroelectric Project
INITIAL STUDY REPORT WATER QUALITY MODELING STUDY (5.6)
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FERC Project No. 14241 Part A - Page 17 June 2014
Figure 5.2-1. Reservoir Model Grid with Bathymetry
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Figure 5.3-1. River Model Grid Below Dam Site (PRM 187.2)
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Figure 5.3-2. River Model Grid Upstream of PRM 80.
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Figure 5.4-1. Enhanced River Model Grid for Focus Area FA-115