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5.0 IMPACT ASSESSMENT METHODOLGY
Chapter 5.0 Impact Assessment Methodology
5.0-1
5.0 Impact Assessment Methodology
5.1 Water Rights Context
This chapter identifies and discusses the specific impact assessment methodologies,
modeling tools, evaluation frameworks and baseline assumptions used in the preparation
of the EIR. It provides the framework upon which the potential environmental review is
assessed in the following chapters. EDWPA‟s obligation under CEQA to disclose and
analyze the direct and reasonably foreseeable indirect environmental effects of the
proposed project presents a challenge. As explained in earlier chapters, the proposed
project seeks the assignment of portions of State-filed water rights applications that, if
approved by SWRCB, would give EDWPA a 1927 water rights priority date. Among the
benefits of the seniority associated with that date is the fact that California water law and
conditions in existing water rights permits for junior downstream appropriators, where
necessary due to drought conditions or regulatory constraints, require the junior
appropriators to reduce or forego their diversions before EDWPA would be required to
curtail its diversions.
Thus, EDWPA could not be made, on its own, to reduce its diversions in order to ensure
the enforcement of Delta or lower American regulatory standards or environmental
conditions deemed minimally acceptable. Rather, that burden would more likely fall on
more junior appropriators downstream on the American River or elsewhere within the
CVP/SWP including the Sacramento River, San Joaquin River, their tributaries, and
Delta. Where a potential or actual adverse environmental outcome requires some water
user to reduce its diversion, the burden will generally fall on those more junior
appropriators where the adverse environmental effect would not occur but for their
incremental diversions above and beyond those of senior water right holders.
One important source of legal authority for assisting the SWRCB in sorting out how
junior, downstream appropriators within the American River watershed may have to
adjust their activities in response to the proposed project is the 1958 water rights decision
known as D-893. In that decision, the State Water Rights Board (predecessor to the
SWRCB) conditioned the water rights of the USBR and the City so as to make them
subordinate to the paramount rights for the use of water originating within the American
River watershed within El Dorado County (In the Matter of Applications 12140, et al. by
the City of Sacramento and other applicants, to appropriate waters of the American River
and its tributaries. (1958) Decision 893 (“D-893”).)
The State Water Rights Board, referring to El Dorado County and other upstream
applicants, prefaced its conditioning of the consumptive right permits of USBR and the
City of Sacramento as follows:
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Protection is afforded these [El Dorado] applicants and other
potential users within upstream sub-area of the American River
watershed by terms to be inserted in permits to divert at points
below them to the effect that diversions under those permits are
and shall remain subject to reduction in the event of appropriation
for use within the watersheds that lie above the diversion works
relating to those permits.
(D-893, slip copy, at pp. 58-59.)
The SWRCB has enforced similar permit conditions protecting paramount rights against
other permit holders in the past, requiring water right holders to abstain from their prior
diversion in favor of the diversions of those in a position of paramountcy. (See In re the
Applications 24578, 24579 to Appropriate from the Underflow of the Santa Ynez River
(1978) D-1486; In the Matter of Application 22423 of the Solvang Municipal Utility
District to Appropriate Underflow from the Santa Ynez River (1969) D-1338; In the
Matter of Applications 11331, 11332, 11761, 11762, 11989 (1958) D-886.) This
precedent suggests that, in the future, a similar approach may be used within the
American River watershed.
Despite the relatively predictable manner in which this legal and regulatory system
allocates the benefits and burdens among senior water rights and junior water rights
holders, the impact assessment methodology used in this EIR nevertheless fully addresses
and analyzes the diversion-related effects of the proposed project as though it represents a
new, direct depletion of water from the existing hydrological system. This approach is
legally conservative in the sense that it errs on the side of possibly overstating, rather than
understating, the actual environmental effects of the project, and is intended to comply
with the letter and the expansive spirit of CEQA, which favors the full disclosure of all
possible adverse environmental effects of projects.
Accordingly, an evaluation of the potential impacts of such new water depletion is a kind
of worst case analysis, assuming a new net depletion of up to 40,000 AFA. Even so, the
analysis will provide a very useful source of information for the SWRCB as it faces
ongoing challenges regarding how to protect important beneficial uses of various kinds
throughout the Sacramento-American River system.
Impact analysis for diversion-related effects was performed at the project-level. Project-
level detailed analyses focused on the potential impacts of diverting the new water right
water at three potential points of diversion; 1) EID‟s existing intake to their El Dorado
Hills Water Treatment Plant on Folsom Reservoir, 2) the White Rock Penstock, and 3)
the American River Pump Station on the North Fork of the American River through an
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exchange. These potential points of diversion have been discussed and described in
detail in Chapter 3.0 Project Description, and Chapter 4.0 Alternatives.
Under the project-level analyses, potential hydrologic changes in the various waterbodies
and waterways affected by the project were evaluated. These affected waterbodies
included those within the Upper American River basin, as well as those downstream
within the CVP/SWP. Given the coordinated nature of the CVP/SWP, any diversion
project in a CVP reservoir or from watercourses feeding into it has the potential to affect
downstream reservoirs and watercourses of the CVP/SWP and the Delta. Hydrologic
modeling was undertaken to quantitatively determine the extent and frequency of any
such changes in the hydrologic regime of the CVP/SWP and local area waterways. This
modeling output was then used as the basis upon which impact analyses for all water-
related resources were preformed.
The primary impact analyses for the EIR, therefore, focused on the hydrological effects
of the proposed project on potentially affected waterbodies and waterways including
those of the local area and broader CVP/SWP, including the Delta.
Alternatively, program-level analyses addressed more generally, the future potential
impacts to resources that were non-diversion related. The non-diversion related impacts
included two categories.
First, new diversion, conveyance, and possibly new treatment facilities and related
infrastructure would be required in the future to take this new water supply. The full
details, timing, and commitments for such infrastructure, however, is not currently
known. No design specifications, siting plans, or corridor alignments are currently
available. However, because of the potential necessity for the future construction of such
facilities, the potential impacts of such facilities (including their construction), to the
extent known, are disclosed and discussed generally at the program-level.
Second, the resources within the water service areas or intended Places of Use were also
assessed at the program-level. This included the various facilities, activities, land uses
and other potentially affected resources within the proposed Places of Use including the
Favorable Areas, as defined in the project description. These facilities and activities are
typically assumed as part of ongoing development activities within urban and rural areas.
Such activities, land uses and resources have already been analyzed in the adopted El
Dorado County General Plan Update and EIR, which this EIR relies upon. A detailed
analysis of those activities, land uses, and resources is not repeated in this EIR.
As noted previously in Chapter 1.0 (Introduction), given the proposed project as
described, there will likely be future CEQA documents that will be required and prepared
to divert, convey, and/or treat and deliver this new water supply. These projects will
result from local agencies (e.g., EID, GDPUD, El Dorado County, etc.) making use of the
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new water made available under this project. These facility projects, however, are future
actions that, currently, have not been proposed and do not have detailed information from
which to undertake specific analyses. This current EIR is intended to provide the
hydrologic, project-level analyses that would support future facility projects, thus
avoiding any need for reassessment of instream hydrologic effects for those projects.
The potential resources and issues addressed in this EIR were identified through a
combination of known issues coupled with public involvement through project scoping.
In addition to two formal scoping meetings conducted during the public review and
comment period on the NOP/Initial Study, informal sessions with various stakeholder
groups and public trust resource agencies were conducted by EDWPA. These
discussions and input helped shape the scope of the EIR.
5.2 Diversion-Related Impact Evaluation
As noted, the diversion-related impact assessment relied upon a hydrologic impact
framework to generate quantitative data with which to evaluate potential impacts to
water-related resources. Such potential impacts were evaluated by comparing the
existing hydrologic condition (or Base Condition) with that of the simulated system after
implementation of the proposed project and alternatives (i.e., diversion of the new water
right). Two mass-balance hydrologic reservoir routing models were used: the ResSim
model for the upper American River basin and the CALSIM II model for CVP/SWP
reservoirs and waterways.
The upper American River basin Base Condition is based on and consistent with the
conditions established in the FERC Relicensing Settlement Agreement for the Upper
American River Project (UARP) and Chili Bar project between Sacramento Municipal
Utility District (SMUD), Pacific Gas & Electric (PG&E), and various governmental and
non-governmental agencies and individuals (SMUD et al, 2007). The use of this differs
from the normal practice of treating existing conditions, as they existed at the time of the
Notice of Preparation, as the “baseline” for purposes of impact analysis (see CEQA
Guidelines, § 15125, subd. (a)). The UARP and Chili Bar project relicensing conditions
were included in the Base Condition for the upper American River basin because this
approach is more conservative for purposes of assessing the significance of impacts
(tending to overstate, instead of understate, impacts) and because the UARP and the Chili
Bar project will be operating under the terms of the Relicensing Settlement Agreement
prior to the implementation of the proposed project. To use language from CEQA case
law, the baseline chosen here is “the actual environment upon which the project will
operate.” (Environmental Planning and Information Council v. County of El Dorado
(1982) 131 Cal.App.3d 350, 354.) For this reason, the approach taken here finds
abundant support in that case law.
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Resource evaluations were broken into two categories: Diversion-related Impacts, and
Indirect or Non-Diversion related Impacts.
Diversion-related impacts could potentially affect the following resources:
Water Supply
Hydropower Generation
Flood Control
Fisheries
Water Quality
Riparian and Riverine Resources
5.2.1 Upper Basin Modeling – HEC-ResSim
HEC-ResSim (Version 3.0.1), a public domain software package developed by the
Hydrologic Engineering Center of the U.S. Army Corps of Engineers (HEC) as a
decision support tool for reservoir regulators, was used for numerical computer modeling
to evaluate the impacts of the proposed project .
Features of ResSim include:
A map-based schematic development environment;
A complex reservoir element that can include multiple dams and outlets;
An operations scheme that can define the reservoir's operating goals and
constraints in terms of pool zones and zone dependent rules;
A set of operation rule types that include release requirements and constraints,
downstream control requirements and constraints, pool elevation or inflow rate-
of-change limits, hydropower requirements, and induced surcharge (emergency
gate operation);
Operation of multiple reservoirs for a common downstream control, including
storage balancing;
Alternative builder to allow for a wide range of "what if" analysis;
Computation time-steps from 15 minutes to 1 day;
Summary Reports and a Release Decision Report; and,
HEC-DSS (a scientific database system developed by HEC) for storage of input
and output data.
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As a starting point, this analysis used an existing ResSim model (Hughes, 2007), jointly
developed by the California Department of Fish & Game (CDFG) and U.S. Forest
Service, as part of SMUD‟s UARP FERC relicensing process. This model is based on the
conditions established in the Relicensing Settlement Agreement for the UARP and Chili
Bar project between SMUD, Pacific Gas & Electric (PG&E), and various governmental
and non-governmental agencies and individuals (SMUD et al, 2007).
Following the CDFG model, the period extending from Water Year (WY) 1975 through
WY 1999 was selected as the study period because of the availability of observed data
and unimpaired flow estimates for this period. Alternate scenarios were created to reflect
the various possible withdrawal cases under the proposed water rights. The model was
used to verify the environmental boundary conditions associated with EDWPA‟s
proposed diversion and provide a means of determining the potential impact to the
reservoirs and watercourses in the project area, relative to those established in the
Settlement Agreement.
5.2.1.1 Approach
The existing ResSim model, with modifications to reflect the diversion at the White Rock
Penstock, was used to generate the time-series for comparison. Since this analysis is
based on a pre-existing model, detailed background information on the model
construction is not provided here. Such information may be found in the supporting
document for the Settlement Agreement ResSim model published by California
Department of Fish & Game (Hughes, 2007). Copies of this document are available for
review at the offices of the El Dorado County Water Agency located at 3932 Ponderosa
Road, Suite 200, Shingle Springs, CA 95682.
The objective of the model is to evaluate the impacts of the proposed EDWPA diversions
on the reservoirs and watercourses in the project area. Modifications were made to the
model to incorporate the proposed diversion and are described in Section Model
Modifications. The evaluation of the impacts of the diversion was possible through a
comparison of the Base Condition (i.e., Settlement Agreement ) with four possible
diversion scenarios (described in Section Diversion Scenarios) using various metrics such
as power generation, rafting flows, reservoir storage, and lake levels (described in
Section Parameters Used for Comparison of Alternatives). Computational limitations of
the model are discussed in Model Computational Limitations. Finally, the period of
evaluation for the results is presented in "Period of Evaluation".
5.2.1.2 Model Modifications
The ResSim model contains a Base Case, which reflects the Relicensing Settlement
Agreement and four proposed diversion scenarios. These different diversion scenarios are
summarized in Table 5.2.1-1. In all scenarios, the total annual diversion has a monthly
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distribution in accordance with the Monthly Water Need Schedule information shown in
Tables 5.2.1-2 and 5.2.1-3.
The following modifications were made to the ResSim model to reflect the diversion
from the White Rock Penstock in physical and operational terms:
Diverted Outlet
A Diverted Outlet was added at Slab Creek Reservoir (identified as EDWPA Diversion)
to describe water diverted just prior to the White Rock Powerhouse.
Table 5.2.1-1
Summary of Model Simulations
Name of Simulation
Location of Diversion
White Rock
Powerhouse
Penstock
Folsom Reservoir
American River
Pump Station
(future)
Base Condition - - -
Proposed Project B 40,000 - -
Proposed Project C 30,000 - 10,000
Reduced Project
Alternative B-2 20,000 - -
Reduced Project
Alternative C-2 15,000 - 5,000
Note: All values are in Acre-Feet and reflect annual diversions. Monthly distribution is shown in Table 5.2.1-2.
Operation of Slab Creek Reservoir
The operation of Slab Creek Reservoir in the Base Scenario model (formerly ResLevel2
from DFG model) is governed by the operation set RecFlow-6. Copies of this set were
made to retain all other parameters, and the copies were then modified to create four new
operation sets, each of which reflects one of the four scenarios being studied. These
operation sets are labeled:
Proposed Project B
Proposed Project C
Reduced Project Alternative B-2
Reduced Project Alternative C-2
Note: These labels were used for modeling identification purposes and are not the CEQA
proposed project and alternatives. The relationship between the modeling nomenclature
and the CEQA proposed project and alternatives is provided in Table 5.2.7-1.
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Table 5.2.1-2
Monthly Diversions at White Rock Penstock
Monthly
Distribution %
Model Simulation
10% 5% 4% 4% 4% 4% 4% 8% 13% 16% 16% 12% 100%
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Total
Proposed
Project B
Monthly
Volume
(AF)
4,000 2,000 1,600 1,600 1,600 1,600 1,600 3,200 5,200 6,400 6,400 4,800
40,000
Average
flow (cfs) 65 34 26 26 29 26 27 52 87 104 107 78
Proposed
Project C
Monthly
Volume
(AF)
3,000 1,500 1,200 1,200 1,200 1,200 1,200 2,400 3,900 4,800 4,800 3,600
30,000
Average
flow (cfs) 49 25 20 20 22 20 20 39 66 78 78 59
Reduced
Project
Alt. B-2
Monthly
Volume
(AF)
2,000 1,000 800 800 800 800 800 1,600 2,600 3,200 3,200 2,400
20,000
Average
flow (cfs) 33 17 13 13 14 13 13 26 44 52 52 39
Reduced
Project
Alt. C-2
Monthly
Volume
(AF)
1,500 750 600 600 600 600 600 1,200 1,950 2,400 2,400 1,800
15,000
Average
flow (cfs) 24 13 10 10 11 10 10 20 33 39 39 29
Note: Scenarios with no diversion at White Rock are not shown here.
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Table 5.2.1-3
Monthly Diversions at Folsom Reservoir
Monthly
Distribution %
Model Simulation
10% 5% 4% 4% 4% 4% 4% 8% 13% 16% 16% 12% 100%
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Total
Proposed
Project A
Monthly
Volume
(AF)
3,000 1,500 1,200 1,200 1,200 1,200 1,200 2,400 3,900 4,800 4,800 3,600
30,000
Average
flow (cfs) 49 25 20 20 22 20 20 39 66 79 79 59
Proposed
Project D
Monthly
Volume
(AF)
4,000 2,000 1,600 1,600 1,600 1,600 1,600 3,200 5,200 6,400 6,400 4,800
40,000
Average
flow (cfs) 65 34 26 26 29 27 27 52 87 104 104 78
Reduced
Project
Alt. A-2
Monthly
Volume
(AF)
1,500 750 600 600 600 600 600 1,200 1,950 2,400 2,400 1,800
15,000
Average
flow (cfs) 24 13 10 10 11 10 10 20 33 39 39 29
Reduced
Project
Alt. D-2
Monthly
Volume
(AF)
2,000 1,000 800 800 800 800 800 1,600 2,600 3,200 3,200 2,400
20,000
Average
flow (cfs) 33 17 13 13 14 13 13 26 44 52 52 39
Note: Scenarios with no diversion at Folsom Reservoir are not shown here.
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Power Generation
The ResSim model is not specifically designed as a tool to evaluate energy generation
impacts; however, the model does report energy generation with sufficient accuracy to be
used to evaluate the overall difference in generation between two alternatives (Hughes,
2007). Power generation is calculated separately for each Upper American River Project
and Chili Bar Project power plants. For evaluation, total generation for both SMUD‟s
Upper American River Project and PG&E‟s Chili Bar Project were evaluated.
Reservoir Storage
Annual inflows in the following reservoirs were evaluated for comparison:
Loon Lake Reservoir
Union Valley Reservoir
Ice House Reservoir
Camino Reservoir
Slab Creek Reservoir
Chili Bar Reservoir
Reservoir Levels
Water levels in the following reservoirs were evaluated for recreational resource impact
purposes:
Loon Lake Reservoir
Union Valley Reservoir
Ice House Reservoir
Camino Reservoir
Slab Creek Reservoir
Chili Bar Reservoir
Rafting Flows
Flows were evaluated in the following reaches of Silver Creek and South Fork (SF)
American River, which are popularly used for whitewater rafting:
Silver Creek above SF American River
SF American River below Slab Creek Reservoir
SF American River below Chili Bar Reservoir
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5.2.1.4 Model Computational Limitations
In order to preserve the nature of the model in its original form no attempt was made to
modify any preexisting model features unless they directly affected the proposed
EDWPA diversions. Wherever the original model simulation encountered numerical
instabilities, these were left unadjusted. When simulation runs were conducted on the
model in its original condition, it appeared that there were minor numerical instabilities
and the model was unable to converge on several instances when computing water levels
for Camino Reservoir. However, these instabilities did not affect the results. However,
after adding the EDWPA diversion at White Rock Penstock, the associated rules and
operation sets, and running the model over a continuous daily time series from WY 75
through WY 99, these instabilities were found to be amplified to the extent that the model
simulation would stall.
When ResSim is unable to converge on a solution after several passes, it automatically
refers to the "Look Back" time-series and picks a value for the particular time-step for
which it has been unable to converge. The model for this study is split in four
simulations representing sub-periods (WY 75-81, WY 82-88, WY 89-95, WY 95-99).
Each simulation (except the first one) was set to „look back‟ on the end result of the
previous simulation period for its starting conditions. There was no single continuous
Look back time-series for ResSim to refer to in case of a severe numerical instability.
Without a Look Back file when instabilities were found in the middle of a simulation
period, the model stalled.
To mitigate this situation, all four simulations were programmed to look back at an
artificial WY1975-1999 Look Back time-series, rather than just the end results of the
preceding time series. The disadvantage to this is that the starting condition of a
simulation period would not match the ending condition of the previous simulation. The
model, however, would quickly seek out appropriate values in a matter of a few time-
steps. Despite the numerical constraints described above, the model provides results that
can be effectively used for impact evaluation purposes since the environmental
assessments are based on comparisons between model simulation outputs. As a tool that
provides comparative data, the seeming limitations in model representation are equitable
(i.e., the same) across all simulations. Bias is eliminated when the comparative
confidence limits are identical across all model simulations.
5.2.1.5 Period of Evaluation
The model was run for the period from WY1975 through WY1999. For ease of
reporting and evaluation, only selected years have been presented in the results. These
years have been selected on the basis of the water year type (i.e., based on amount of
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rainfall) - the Hydrology Technical Report classified each month between WY 1975 and
WY 2001 as Critically Dry, Dry, Below Normal, Above Normal, and Wet.
WY 1977 was selected to represent a Critically Dry year, WY 1992 as Dry, WY 1990 as
Below Normal, and WY 1997 as a Wet year. However, in the study period of WY1975-
1999, there is no water year that showed unambiguous qualities in order to be represented
as an Above Normal Year. The current model runs have been programmed to „look back‟
at a single "Look Back" time-series. This time-series, which was part of the original
CDFG model, stops at the end of WY 1999. As a result, the latest version of the model
cannot be run past WY 1999. Finally, the Above Normal water year was omitted since
there was no year that provided a good representation within the dataset and values could
be inferred using the Below Normal and Wet data.
5.2.1.3 Modeling Simulations
Under each of these modeling simulations, eponymous new rules were created to reflect
the proposed diversions. These rules operate release from Slab Creek Reservoir through
the EDWPA Diversion (entity identified in the model as “Slab Creek Reservoir–EDWPA
Diversion”). Each of these rules contains Release Functions which reflect the monthly
flows shown in Table 5.2.1-2.
To avoid redundancy, only some of the EIR alternatives were modeled with ResSim. The
Base Condition and the maximum and minimum proposed diversions were modeled to
provide the appropriate environmental bracket. It is assumed that all other diversion
permutations would impart impacts that would fall within these boundary extremes. The
various modeling simulations to account for the various diversion scenarios considered
for this analysis are described below and previously summarized in Table 5.2.1-1. In all
simulations, the total annual diversion has a monthly distribution in accordance with the
Monthly Water Need Schedule summarized in Tables 5.2.1-2 and 5.2.1-3.
EDWPA Null
To ensure that no water is diverted to EDWPA Diversion under the Base Condition, a
rule called “EDWPA Null” was created under the operation set RecFlow-6 (which
operates the Base Condition). This rule restricts the diversion to zero throughout the
year.
Time-step
A time-step of one day was adopted for the model.
Base Condition
The Base Condition reflects conditions under the Settlement Agreement. The Settlement
Agreement has established various environmental thresholds (e.g., minimum instream
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flows, limits on tunnel diversions, provisions for geomorphic releases etc) which were
followed. This model simulation does not include any additional water diversions above
current conditions. The existing diversions are assumed to take place throughout the year
based on the monthly water need schedule that was developed for the project.
Proposed Project B
This model simulation supports a total annual diversion of 40,000 AF from the turnout on
White Rock Powerhouse Penstock. The diversions are assumed to take place throughout
the year based on the monthly water need schedule that was developed for the project.
Proposed Project C
This model simulation scenario supports a total annual diversion of 40,000 AF comprised
of 30,000 AF from the turnout on White Rock Powerhouse Penstock and 10,000 AF from
the American River Pump Station. The diversions are assumed to take place throughout
the year based on the monthly water need schedule that was developed for the project.
Reduced Project Alternative B-2
This model simulation supports a reduced total annual diversion of 20,000 AF from the
turnout on White Rock Powerhouse Penstock. The diversions are assumed to take place
throughout the year based on the monthly water need schedule that was developed for the
project.
Reduced Project Alternative C-2
This model simulation supports a reduced total annual diversion of 20,000 AF comprised
of 15,000 AF from the turnout on White Rock Powerhouse Penstock and 5,000 AF from
the American River Pump Station. The diversions are assumed to take place throughout
the year based on the monthly water need schedule that was developed for the project.
Parameters Used for Comparison of Alternatives
To quantitatively evaluate the potential impacts from each of the four model simulations,
relative to the Base Condition, it was necessary to identify parameters which could be
easily discredited for numerical comparison. The parameters chosen for comparison have
been described above.
5.2.2 CALSIM II
CALSIM II is a model jointly developed by the U.S. Bureau of Reclamation (USBR) and
the California Department of Water Resources (DWR) for planning studies relating to
CVP and SWP operations. The primary purpose of CALSIM II is to evaluate the water
supply reliability of the CVP and SWP at current or future levels of development (e.g.
2001, 2030), with and without various assumed future facilities, and with different modes
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of facility operations. An extensive model, CALSIM II simulates monthly operations of
the following water storage and conveyance facilities:
Trinity, Lewiston, and Whiskeytown reservoirs (CVP);
Spring Creek and Clear Creek tunnels (CVP);
Shasta and Keswick reservoirs (CVP);
Oroville Reservoir and the Thermalito Complex (SWP);
Folsom Reservoir and Lake Natoma (CVP);
New Melones Reservoir (CVP);
Millerton Lake (CVP);
C.W. Jones (CVP), Contra Costa (CVP) and Harvey O. Banks (SWP) pumping
plants; and
San Luis Reservoir (shared by CVP and SWP).
To varying degrees, CALSIM II nodes also define CVP/SWP conveyance
facilities including the Tehama-Colusa, Corning, Folsom-South, and Delta-
Mendota canals and the California Aqueduct. Other non-CVP/SWP reservoirs or
rivers tributary to the Delta also are modeled in CALSIM II, including:
New Don Pedro Reservoir;
Lake McClure; and
Eastman and Hensley lakes.
CALSIM II uses a mass balance approach to simulate the occurrence, regulation, and
movement of water from one river reach (computation point or node) to another within
monthly time steps. Various physical processes (e.g., surface water inflow or accretion,
flow from another node, groundwater accretion or depletion, and diversion) are simulated
or assumed at each node as necessary. Operational constraints, such as reservoir size,
seasonal storage limits, and minimum flow requirements, also are defined for each node.
Accordingly, flows are specified as a mean flow for the month, and reservoir storage
volumes are specified as end-of-month values. In addition, modeled X2 (2 parts per
thousand [ppt] near bottom salinity isohaline) locations are specified as end-of-month
locations, Delta outflows are specified as mean outflows for each month, and Delta
export-to-inflow (E/I) ratios are specified as mean ratios for each month.
The hydrologic period of record used by CALSIM II has recently been extended so that
today, the model can simulate system operations over an 82-year period. The model
assumes that facilities, land use, water supply contracts, and regulatory requirements are
Chapter 5.0 Impact Assessment Methodology
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constant over this period, and represent a fixed level of development (e.g., 2001 or 2030).
The historical flow record from 1921 to 2003, adjusted for the influence of land use
change and upstream flow regulation, is used to represent the possible range of water
supply conditions that could conceivably occur. This is a reasonable assumption and one
that presumes that past hydrologic conditions are a good indicator of future hydrologic
conditions. As discussed later, this concept of stationarity in hydrologic conditions has
come under significant scrutiny in recent years, both temporally and spatially, with
climate change representing a key causal factor in this uncertainty (see Chapter 8 –
Climate Change).
The model simulates one month of operation at a time, with the simulation passing
sequentially from one month to the next, and from one year to the next. Each estimate
that the model makes regarding stream flow is the result of defined operational priorities
(e.g., delivery priorities to water right holders, and water contractors), physical
constraints (e.g., storage limitations, available pumping and channel capacities), and
regulatory constraints (flood control, minimum instream flow requirements, Delta
outflow requirements). Certain decisions, such as the definition of water year type, are
triggered once a year, and affect water delivery allocations and specific stream flow
requirements. Other decisions, such as specific Delta outflow requirements, vary from
month to month. CALSIM II output contains estimated flows and storage conditions at
each node for each month of the simulation period. Simulated flows are mean flows for
the month, reservoir storage volumes correspond to end-of month storage.
CALSIM II, together with associated environmental models (e.g., USBR‟s Trinity,
Shasta, Whiskeytown, Oroville, and Folsom Reservoir Water Temperature Models;
USBR‟s Trinity, Sacramento, Feather, and American (with Automated Temperature
Selection Procedure [ATSP]) River Water Temperature Models; USBR‟s Feather, and
Sacramento River Early Life Stage Chinook Salmon Mortality Models; the Long Term
Gen Model; and the General Purpose Output Generation Tool) provided the predictive
hydrology and environmental outputs necessary to determine potential water-related
resource impacts throughout the CVP/SWP as a result of the proposed action and
alternatives.
A more detailed discussion of CALSIM II and the modeling impact framework used in
this EIR is provided below (all modeling assumptions specific to the individual model
simulations are provided in Modeling Technical Memorandum, Appendix G).
5.2.2.1 CALSIM Utility
At the present time, CALSIM II is considered the best available tool for modeling the
integrated CVP and SWP and is the only system-wide hydrologic model being used by
USBR and DWR to conduct planning and impact analyses of potential projects. While
Chapter 5.0 Impact Assessment Methodology
5.0-16
these agencies developed the model for project-related purposes (i.e., CVP/SWP actions),
the model has been employed for various other purposes with varying degrees of success.
These limitations are discussed in more detail later.
As the official model for California‟s two largest inter-regional projects with implications
for statewide and Central Valley water operations and planning, CALSIM II results are
often at the center of many technical and policy controversies. As such, CALSIM II, not
unlike its predecessors, PROSIM 2000 and PROSIM, warrants and, in fact, has received
considerable scrutiny from the water resources and environmental communities. The
range of issues raised has been diverse, and includes a variety of issues and perspectives
related to water supply reliability, environmental management and performance, water
demands, economics, documentation, changing hydrology and climate, software, and
regulatory compliance.
A primary intended use of CALSIM II is to estimate the impacts and benefits of large-
scale proposed projects and regulatory actions on the statewide system. Much of the
initial focus of system-wide modeling of this nature was intended to help determine
export quantities and timing. Current analyses using CALSIM II include, among others,
proposed CALFED storage projects, including In-Delta storage, North of Delta Off-
stream Storage (Sites Reservoir), expansion of Los Vaqueros and Shasta reservoirs,
storage in the Upper San Joaquin Basin, and conjunctive use both north and south of the
Delta. Of particular note, CALSIM II has also been used in the Biological Assessment
for the Long-Term Coordination of the CVP and SWP and in both Biological Opinions
on this action.
At the local level, many agencies also rely on CALSIM II results to estimate potential
impacts to the integrated system based on their own specific project actions. CALSIM II
has been used in the P.L.101-514 New CVP Water Service Contracts, Freeport Regional
Project, the Lower Yuba River Accord, the Sacramento Area Water Forum Lower
American River Flow Standard, and numerous Warren Act contracting actions, to name
but a few. Similar to the reliance on predecessor models, the use of CALSIM II and any
of its future revisions is anticipated to continue in the future.
5.2.2.2 CALSIM II Operation
The operations of CALSIM II have been described in numerous documents. The
following discussion is taken from DWR (2006, 2005, 2003a, 2003b); Ferreira et al.
(2005); Draper et al. (2004); and the Freeport Regional Water Project EIS/EIR (2003).
CALSIM II utilizes optimization techniques to route water through a watershed network
on a monthly time-step. A linear programming (LP)/mixed integer linear programming
(MILP) solver determines an optimal set of decisions for each time period given a set of
weights and system constraints. A key component for specification of the physical and
Chapter 5.0 Impact Assessment Methodology
5.0-17
operational constraints is the WRESL language. The model user describes the physical
system (e.g., dams, reservoirs, channels, pumping plants, etc.), operational rules (e.g.,
flood-control diagrams, minimum flows, delivery requirements, etc.), and priorities for
allocating water to different uses in WRESL statements.
CALSIM II includes a hydrology developed jointly by USBR and DWR. Water
diversion requirements of purveyors (demands), natural stream accretions and depletions,
river basin inflows, irrigation efficiencies, return flows, non-recoverable losses, and
groundwater operation are components that make up the hydrology used in CALSIM II.
Sacramento Valley and tributary basin hydrology is developed using a process designed
to adjust the historical sequence of monthly stream flows to represent a sequence of flows
at either current or future levels of development. Adjustments to historic water supplies
are determined by imposing land use on historical meteorological and hydrologic
conditions. San Joaquin River basin hydrology is developed using fixed annual demands
and regression analysis to develop accretions and depletions. The resulting hydrology
represents the water supply available from Central Valley streams to the CVP and SWP
at an established level of development.
CALSIM II uses DWR‟s Artificial Neural Network (ANN) model to simulate the flow-
salinity relationships for the Delta. The ANN model correlates DSM2 model-generated
salinity at key locations in the Delta with Delta inflows, Delta exports, and Delta Cross
Channel operations. The ANN flow-salinity model estimates electrical conductivity at
the following four locations for the purpose of modeling Delta water quality standards:
Old River at Rock Slough, San Joaquin River at Jersey Point, Sacramento River at
Emmaton, and Sacramento River at Collinsville. In its estimates, the ANN model
considers antecedent conditions up to 148 days, and considers a “carriage-water” type of
effect associated with Delta exports.
The delivery logic CALSIM II utilizes in determining deliveries to North-of-Delta and
South-of-Delta CVP and South-of-Delta SWP contractors uses runoff forecast
information that incorporates uncertainty and standardized rule curves (i.e., Water Supply
Index versus Demand Index Curve) to estimate the water available for delivery and
carryover storage. Updates of delivery levels occur monthly from January 1 through May
1 for the SWP and March 1 through May 1 for the CVP as water supply parameters
become more certain. The South-of Delta SWP delivery is determined based upon water
supply parameters and operational constraints. The CVP system wide delivery and
South-of-Delta delivery are determined similarly upon water supply parameters and
operational constraints with specific consideration for export constraints.
CALSIM II incorporates procedures for dynamic modeling of Section 3406(b) (2) of the
CVPIA and the Environmental Water Account (EWA), under the CALFED Framework
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5.0-18
and Record of Decision (ROD). Per the October, 1999 Decision and the subsequent
February, 2002 Decision, CVPIA 3406(b)(2) accounting procedures are based on system
conditions under operations associated with SWRCB D-1485 and D-1641 regulatory
requirements. Similarly, the operating guidelines for selection of actions and allocation
of assets under the EWA are based on system conditions under operations associated with
SWRCB D-1641 regulatory requirements. This requires sequential layering of multiple
system requirements and simulations. CVPIA 3406(b) (2) allocates 800 TAF (600 TAF
in Shasta critical years) of CVP project water to targeted fish actions. The full amount
provides support for SWRCB D-1641 implementation. According to monthly
accounting, 3406(b) (2) actions are dynamically selected according to an action matrix.
Several actions in this matrix have defined reserve amounts that limit 3406(b) (2)
expenditures for lower priority actions early in the year such that the higher priority
actions can be met later in the year.
5.2.2.3 CALSIM II Simulations
The applicability of CALSIM II in environmental analyses is based on its ability to
provide comparative data results. This is an important point since CALSIM II, as with
most gross-scale, long time-step (monthly) hydrologic simulations, are appropriate for the
purposes upon which they were designed but not necessarily for other evolved and
evolving applications. While CALSIM II has, and continues to be used for
environmental analyses of specific project (or action) increments, its strength does not lie
in those types of applications. Nevertheless, with an integrated CVP/SWP and
coordinated operations throughout the many interconnecting watersheds, CALSIM II is a
useful and accepted tool to gauge system-wide hydrological changes resulting from a
particular action. Again, as noted, it does so within a comparative framework where, the
results of the with-project condition are compared against the baseline condition.
Accordingly, the results from a single simulation may not necessarily represent the exact
operations for a specific month or year, but should reflect long-term trends. Since
CALSIM II is not designed to accurately predict operations and flows, results from
individual months should be considered only in the context of overall trends and
averages. CALSIM II represents operational or regulatory thresholds through the use of
step functions. Due to CALSIM's dynamic responses to system conditions, slight
changes in model inputs or operations could trigger responses which may significantly
vary on an individual monthly basis between the Base Condition and “Project”
simulation. These dynamic responses, however, often average out over longer time
periods. It is these longer-term trends which are useful in determining potential effects of
larger diversion projects on the coordinated CVP/SWP.
Chapter 5.0 Impact Assessment Methodology
5.0-19
5.2.2.4 CALSIM II Limitations
Regardless of the model, models only approximate natural phenomena. In fact, most
models are inherently inexact since the mathematical descriptions upon which they are
based are either imperfect and/or our understanding of the inherent processes (that we are
trying to simulate) is incomplete. It is well accepted that the mathematical parameters
used in models which are intended to represent real processes are often uncertain. This
uncertainty arises because these parameters are empirically determined and often attempt
to represent multiple processes. Additionally, the initial or starting conditions and/or the
boundary conditions in a model are often not well known. CALSIM II, despite its
powerful capabilities, remains a model and, as such, is subject to the same issues
regarding limitations as any other model.
As noted previously, CALSIM II is able to simulate the integrated CVP/SWP system
over the 83-year historical hydrology. In theory, such simulation allows model users to
assess the effects that certain actions would have had on the system had they been
implemented in any year of the historical record. The ability of the model to represent a
predictive indicator of the effect of certain actions into the future, however, largely
depends on the representative nature of the historical hydrology, relative to likely future
hydrology. This is a very important point. With growing concerns throughout the
scientific community, past hydrology, it is felt, may not be a good indicator of the
hydrological conditions one could expect in the future. A good example of this concern
is related to global climate change. While most water practitioners accept climate change
as an eventual reality and agree with its inevitability, the degree to which it will affect
specific resources and the temporal pattern of that effect say, over a season, is still largely
a subject of continuing debate. Water managers today have begun to consider global
climate change in earnest when planning for the future. Unfortunately, at the time
modeling for this proposed action was completed, CALSIM II was not well suited to
model perturbed hydrology or other future scenarios where non-stationarity in hydrologic
or meteorologic processes derived at the basin-scale are relevant. Physical experimental
designs where watershed processes under a variable hydrometeorologic regime are
evaluated have not been incorporated into CALSIM II. CALSIM II has not yet been
calibrated against physical snowmelt and altered runoff generating processes resulting
from possible climatic perturbations. Current CALSIM II work, however, is moving
towards improving those types of analyses.
CALSIM II also lacks detailed documentation regarding the known limitations and
weakness of the model. Without a clear understanding of the model‟s formulation, water
managers have been wary of applying it in a predictive (absolute) mode. A long-standing
issue is that error bars need to be specified for all CALSIM II output; this would be
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5.0-20
especially applicable where the model was being used in predictive mode (Ferreira et al.,
2005).
From a temporal perspective, there is ongoing concern that CALSIM II‟s monthly time
step cannot accurately capture hydrologic variability and, thus, does not compute water
exports and export capacity accurately, both of which are significant factors in CVP/SWP
operations. CALSIM II‟s inability to capture within-month variations often results in
overestimates of the volume of water the projects can export from the Bay-Delta and
makes it seem easier to meet environmental standards than it is in real-time operations.
Many of the system‟s operations function, in fact, on a shorter time scale. CALSIM II
cannot represent them well given its current formulation. On the other hand, it is unclear
if reducing the time step would result in more accurate or more useful data results given
the additional data and assumptions that would be needed to characterize the system at
this finer temporal resolution. A daily time step might, in fact, worsen some problems
due to questions regarding the precise timing of short events (Ferreira et al., 2005).
CALSIM is also limited by its geographic coverage. For CALSIM II to be a truly State-
wide model, it needs to fully cover the Bay Area, Tulare Basin (including the Friant-Kern
and Madera canals, eastside San Joaquin reservoirs, and Millerton), Yuba River Basin
(for potential water transfer opportunities), Colorado River, Colorado River and Los
Angeles aqueducts, and all local Southern California projects. Coupled with a need for
greater geographic coverage, CALSIM II should also include management options
available in California at both the regional and local levels. Inter– and intra-agency water
transfers are now commonplace, as are other management options such as groundwater
banking (e.g., aquifer-storage-recovery), conjunctive use, desalination, and water
conservation. Accordingly, to effectively simulate the array of potential water operations
available within the State, CALSIM II needs to include a wider range of management
options, facilities, and regions. It is vital that those involved in the management of
California‟s water be able to analyze how local, regional, and state facilities and options
best go together. California does not currently have a model or modeling framework
capable of such integrated analysis, to parallel the kinds of integrated management
thinking being pursued at local, regional, and statewide levels (Ferreira et al., 2005).
CALSIM II is also currently lacking in its ability to perform hydropower computations,
which is an important component of the federal CVP system. This should ideally include
risk-based power capacity evaluation, and possibly incorporate the ISM (indexed
sequential hydrologic modeling) method that Reclamation has used for many years in
hydropower capacity analysis. Also, hydropower should not simply be an after-the-fact
calculation as it is with the use of the Long-Term Gen Model, but explicitly included in
the system objectives and incorporated into CALSIM II.
Chapter 5.0 Impact Assessment Methodology
5.0-21
With respect to groundwater, CALSIM II is acknowledged as being significantly limited.
Groundwater is modeled as a series of inter-connected lumped-parameter basins.
Groundwater pumping, recharge from irrigation, stream-aquifer interaction and inter-
basin flow are calculated dynamically by the model. The purpose of the multi-cell
groundwater model is to better represent groundwater levels in the vicinity of the streams
to better estimate stream gains and losses to aquifers.
In the Sacramento Valley, groundwater is explicitly modeled in CALSIM II using a
multiple-cell approach based on Drainage Service Area (DSA) boundaries. For the
Sacramento Valley, there are a total of 14 groundwater cells. Currently, no multi-cell
model has been developed for the San Joaquin Valley. Instead, stream-aquifer interaction
is estimated from historical stream gage data. These flows are fixed and are not
dynamically varied according to stream flows or groundwater elevation.
Groundwater availability from aquifers is poorly represented in the model. This results
from the fact that aquifers in the northern part of the state (Sacramento Valley) have not
been thoroughly investigated regarding their storage and recharge characteristics. Thus,
in the model, upper bounds on potential pumping from aquifers remain undefined.
Realistic upper bounds to pumping from any of the aquifers represented in the model
need to be developed and implemented. In addition, historical groundwater pumping is
used to estimate local groundwater sources in the model; however, the information on the
historical pumping is very limited, causing these pumping rates to be very uncertain.
Improved pumping information is required and an analysis of the effect of this
uncertainty on model results needs to be conducted. In general, the level of
representation of groundwater in CALSIM II is not optimal.
Finally, CALSIM II is still relatively new and many of today‟s water managers remain
unfamiliar with its full capabilities and limitations. The fact that CALSIM II is priority-
based rather than rule-based, adds to this uncertainty, since the model‟s structure and
logic differ significantly from previous models (e.g., DWRSIM and PROSIM). The
strengths and alleged weaknesses of CALSIM II are not only technical (software, data,
and methods), but also institutional in how this model has been developed and utilized.
Nevertheless, CALSIM II remains an important component of any overall integrated
approach to impact assessment for water projects operating within the framework of the
overall CVP/SWP system. Even with its limitations, the model represents the best
available hydrological tool for assessing the impacts of new water projects within that
overall system.
5.2.3 Water Temperature Modeling
USBR has developed water temperature models for the Trinity, Sacramento, Feather, and
American rivers. The models have both reservoir and river components to simulate water
Chapter 5.0 Impact Assessment Methodology
5.0-22
temperatures in five major reservoirs (Trinity, Whiskeytown, Shasta, Oroville, and
Folsom); four downstream regulating reservoirs (Lewiston, Keswick, Thermalito, and
Natoma); and four main river systems (Trinity, Sacramento, Feather, and American).
The following sections provide additional detail regarding the reservoir and river
components of the water temperature models, respectively. Additional details regarding
USBR‟s water temperature models are well documented in the Central Valley Project
Improvement Act (CVPIA) Draft Programmatic EIS Technical Appendix, Volume Nine.
These water temperature models also are documented in the report titled: U.S. Bureau of
Reclamation Monthly Temperature Model Sacramento River Basin. The water
temperature information from these documents is hereby incorporated by reference and is
briefly summarized below. Copies of these documents are available for review at the
offices of the El Dorado County Water Agency located at 3932 Ponderosa Road, Suite
200, Shingle Springs, CA 95682.
5.2.3.1 USBR’s Reservoir Water Temperature Models
USBR‟s reservoir models simulate monthly water temperature profiles in five major
reservoirs: Trinity, Whiskeytown, Shasta, Oroville, and Folsom. The vertical water
temperature profile in each reservoir is simulated in one dimension using monthly
storage, inflow and outflow water temperatures and flow rates, evaporation, precipitation,
solar radiation, and average air temperature. The models also compute the water
temperatures of dam releases. Release water temperature control measures in reservoirs,
such as the penstock shutters in Folsom Reservoir and the temperature control device
(TCD) in Shasta Reservoir, are incorporated into the models.
Reservoir inflows, outflows, and end-of-month storage calculated by CALSIM II and
post-processing applications are input into the reservoir water temperature models.
Additional input data include meteorological information and monthly water temperature
targets that are used by the model to select the level from which reservoir releases are
drawn. Water TCDs, such as the outlet control device in Shasta Dam, the temperature
curtains in Whiskeytown Dam, and the penstock shutters in Folsom Dam, are
incorporated into the simulation. Model output includes reservoir water temperature
profiles and water temperatures of the reservoir releases. The reservoir release water
temperatures are then used in the downstream river water temperature models, as
described in the next section.
Automated Temperature Selection Procedure
The Automated Temperature Selection Procedure (ATSP), developed by HDR|SWRI,
works with the Folsom Reservoir temperature model to optimize the use of Folsom
Reservoir‟s cold water pool throughout the year for the benefit of downstream aquatic
resources. The procedure starts with multiple sets of monthly temperature targets on the
Chapter 5.0 Impact Assessment Methodology
5.0-23
American River at Watt Avenue. These targets are designed to provide the optimum
biological benefit throughout the year to the downstream aquatic resources for varying
levels of cold water availability. The procedure selects a set of targets for each year and
runs the Folsom Reservoir temperature model for the period of record. The results are
then compared to the targets for each year to see if they were met. If the targets were
met, a new set with higher biological benefit is selected; if they are not met, a new set
with lower biological benefit is selected. Each year is treated independently, that is, each
year has its own set of targets based on the specific characteristics of that year that may
be different from any other year. The procedure continues until the selected targets each
year represent the highest level of biological benefit that can be met for that year.
EID Temperature Control Device
The Folsom Reservoir temperature model does not explicitly model any TCD on the EID
diversion; however the model does include a TCD on the main downstream release
outlets and at the Folsom Pump Station. The input for the Folsom Reservoir temperature
model is generated by a utility that reads flow data from the CALSIM II output and
prepares the inputs for the temperature model. To implement an EID TCD, under future
cumulative conditions, the CALSIM II output is copied and the EID diversion is added to
the flow of the Folsom Pump Station then set to 0 to create a “virtual” CALSIM II output
that can be read by the utility to generate the Folsom Reservoir Temperature model input.
The effect is that the Folsom Temperature model will now route the EID diversion
through the Folsom Pump Station TCD as an approximation of a TCD on the EID
diversion. The volume of the release to the American River is not changed and the water
balance is maintained at Folsom Reservoir.
5.2.3.2 USBR’s River Water Temperature Models
USBR‟s river water temperature models utilize the calculated temperatures of reservoir
releases, much of the same meteorological data used in the reservoir models, and
CALSIM II outputs for river flow rates, gains and water diversions. Mean monthly water
temperatures are calculated at multiple locations on the Sacramento, Feather, and
American rivers.
Reservoir release rates and water temperatures are the boundary conditions for the river
water temperature models. The river water temperature models compute water
temperatures at 52 locations on the Sacramento River from Keswick Dam to Freeport,
and at multiple locations on the Feather and American rivers. The river water
temperature models also calculate water temperatures within Lewiston, Keswick,
Thermalito, and Natoma reservoirs. The models are used to estimate water temperatures
in these reservoirs because they are relatively small bodies of water with short residence
Chapter 5.0 Impact Assessment Methodology
5.0-24
times; thereby, on a monthly basis, the reservoirs act as if they have physical
characteristics approximating those of riverine environments.
5.2.4 Early Life Stage Salmon Mortality Modeling
USBR‟s Early Life Stage Chinook Salmon Mortality Models (Salmon Mortality Models)
uses water temperatures calculated for specific reaches of the Sacramento and Feather
rivers. These are used as inputs to estimate annual mortality rates of Chinook salmon
during specific early life stages. For the Sacramento River analyses, the model estimates
mortality for each of the four Chinook salmon runs: fall, late fall, winter, and spring. For
the Feather River analyses, the model1 produces estimates of only fall-run Chinook
salmon mortality. Since hydrologic conditions in the Yuba River are not characterized in
USBR‟s current Salmon Mortality Models, it is not possible to estimate changes in early
life stage mortality for Chinook salmon in the lower Yuba River using this modeling tool.
The Salmon Mortality Models produce a single estimate of early life stage Chinook
salmon mortality in each river for each year of the simulation. The overall salmon
mortality estimate consolidates estimates of mortality for three separate Chinook salmon
early life stages: (1) pre-spawned (in utero) eggs; (2) fertilized eggs; and (3) pre-
emergent fry. The mortality estimates are computed using output water temperatures
from USBR‟s water temperature models as inputs to the Salmon Mortality Models.
Thermal units (TUs), defined as the difference between river water temperatures and
32°F, are used by the Salmon Mortality Models to track life stage development, and are
accounted for on a daily basis. For example, incubating eggs exposed to 40°F water for
one day would experience 8 TUs. Fertilized eggs are assumed to hatch after exposure to
750 TUs. Fry are assumed to emerge from the gravel after being exposed to an additional
750 TUs following hatching.
Since the models are early life stage based, that is, they are limited to calculating
mortality during the early life stages; they do not evaluate potential impacts to later life
stages, such as recently emerged fry, juvenile out-migrants, smolts, or adults.
Additionally, the models do not directly consider factors other than water temperature
that may affect early life stage mortality, such as adult pre-spawn mortality, instream
flow fluctuations, redd superimposition, and predation.
1 For the purposes of improved technical accuracy and analytical rigor, simulated Chinook salmon early life stage
survival estimates specific to the Feather River are derived from a revised version of Reclamation‟s Salmon
Mortality Model (2004), which incorporates new data associated with: (1) temporal spawning and pre-spawning
distributions; and (2) mean daily water temperature data in the Feather River. Although the updated Feather River
information serving as input into the model deviates slightly from that which was used in Reclamation‟s OCAP BA,
both versions of the model are intended for planning purposes only, and thus should not be used as an indication of
actual real-time in-river conditions. Because a certain level of bias is inherently incorporated into these types of
planning models, such bias is uniformly distributed across all modeled simulations, including both the Project
Alternatives and the bases of comparison, regardless of which version of the model is utilized.
Chapter 5.0 Impact Assessment Methodology
5.0-25
Since the Salmon Mortality Models operate on a daily time-step, a procedure is required
to convert the monthly water temperature output from the water temperature models into
daily water temperatures. The Salmon Mortality Models compute daily water
temperatures based on the assumption that average monthly water temperature occurs on
the 15th of each month, and interpolate daily values from mid-month to mid-month.
Output from the Salmon Mortality Models provide estimates of annual (rather than
monthly mean) losses of emergent fry from egg potential (i.e., all eggs brought to the
river by spawning adults)
5.2.5 Long-Term GEN Hydropower Model
The Long Term Gen Model is a CVP power model developed to estimate the CVP power
generation, capacity, and project use (i.e., CVP usage) based on the operations defined by
a CALSIM II simulation. Created using Microsoft‟s Excel spreadsheet with extensive
Visual Basic programming, the Long Term Gen Model computes monthly generation,
capacity, and project use (e.g., pumping power demand) for each CVP power facility for
each month of the CALSIM II simulation.
The Long Term Gen Model does not compute the energy requirement or loads at the EID
pumping plant directly. It does, however, compute the pumping power requirements for
the diversion at CALSIM Node 8, which represents several diversions from Folsom
Reservoir, including the EID diversion.
5.2.6 Historical Hydrology – Projected Application
The period of record used in the hydrologic modeling for this EIR extended for the water
years from 1921 through 2003 (82-years). The period of record for the water temperature
modeling extended from water years 1923 through 2003 (81-years). Similarly, early life
stage salmon mortality modeling also used an 81-year period of record. As discussed
previously, these periods, based on the historic hydrologic record, are deemed to be
representative of the natural variation in hydrology that is characteristic of California in
recent times. It includes dry-periods (1928-1934 and 1977), wet-periods (1986), and
variations in between. Extended drought, periods of high precipitation and resultant
runoff, as well as “normal” water years are included in this period of record.
5.2.7 ResSim and CALSIM II Model Simulations Used in this EIR
The proposed project, as defined, as well as the range of alternatives that were carried
forward for detailed analysis in the EIR was correlated with specific ResSim and
CALSIM II simulations (i.e., model runs). Each of the model runs are set out in Table
5.2.7-1 and 5.2.7-2 below.
Chapter 5.0 Impact Assessment Methodology
5.0-26
Table 5.2.7-1
ResSim Model Runs
Correlated with the EIR Proposed Project and Alternatives
Model
Run
Corresponding Model
Simulation Label
Used in EIR
Details of Model Run
Base Condition
Run 1 Base Condition (0 AFA Total Increment)
Base Condition hydrology at 2005
Proposed Project Runs
Run 2 Proposed Project “B”
(40,000 AFA Total Increment)
Modeled as 40,000 AFA diversion at White Rock
Penstock
Run 3 Proposed Project “C”
(40,000 AFA Total Increment)
Modeled as 30,000 AFA diversion at White Rock
Penstock (assumed 10,000 AFA diverted at
American River Pump Station)
Alternatives Runs
Run 4 Reduced Project
Alternative “B-2”
(20,000 AFA Total Increment)
Modeled as 20,000 AFA diversion at White Rock
Penstock
Run 5 Reduced Project
Alternative “C-2”
(20,000 AFA Total Increment)
Modeled as 15,000 AFA diversion at White Rock
Penstock (assumed 5,000 AFA diverted at American
River Pump Station)
Future Cumulative Runs
As there are no anticipated projects or changes in future diversions in the Upper
American River basin that have not already been included in the Settlement Agreement
and made part of the ResSim Base Condition. Accordingly, no ResSim Future
Cumulative Modeling runs were modeled.
Note: The “B” and “C” postscripts represent permutations of the proposed project from a ResSim modeling perspective since the
options for diversion, as defined by the project, are several. The proposed project includes the flexibility to divert all of the water at
the White Rock Penstock or, partition the diversions between Folsom Reservoir and the American River Pump Station.
Chapter 5.0 Impact Assessment Methodology
5.0-27
Table 5.2.7-2
CALSIM II Model Runs
Correlated with the EIR Proposed Project and Alternatives
Model
Run
Corresponding Model
Simulation Label
Used in EIR
Details of Model Run
Base Condition
Run 1 Base Condition (0 AFA Total Increment)
Base Condition hydrology at 2005
Proposed Project Model Runs
Run 2 Proposed Project “A”
(40,000 AFA Total Increment)
Modeled as 30,000 AFA direct depletion from
Folsom Reservoir; and, Modeled as 10,000 AFA less
inflow into Folsom Reservoir (assumed diverted at
American River Pump Station)
Run 3 Proposed Project “B”
(40,000 AFA Total Increment) Modeled as 40,000
AFA less inflow into Folsom Reservoir (assumed
diverted at Whiterock Penstock)
Alternatives Model Runs
Run 4 Reduced Project
Alternative “A-2”
(20,000 AFA Total Increment)
Modeled as 15,000 AFA direct depletion from
Folsom Reservoir; and, Modeled as 5,000 AFA less
inflow into Folsom Reservoir (assumed diverted at
American River Pump Station)
Run 5 Reduced Project
Alternative “B-2”
(20,000 AFA Total Increment)
Modeled as 20,000 AFA less inflow into Folsom
Reservoir (assumed diverted at Whiterock Penstock)
Future Cumulative Model Runs
Run 6 Future Cumulative
Condition
Modeled as 30,000 AFA direct depletion from
Folsom Reservoir; and, Modeled as 10,000 AFA less
inflow into Folsom Reservoir (assumed diverted at
American River Pump Station)
Run 7
Future Cumulative
Condition without
Proposed Project “A”
Modeled without 30,000 AFA direct depletion from
Folsom Reservoir; and, Modeled without 10,000
AFA less inflow into Folsom Reservoir (assumed
diverted at American River Pump Station)
Note: The “A” and “B” postscripts represent permutations of the proposed project from a CALSIM modeling perspective since the options for diversion, as defined by the project, are several. The proposed project includes the flexibility to divert all of the water at
the Whiterock Penstock or, partition the diversions between Folsom Reservoir and the American River Pump Station.
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5.0-28
The various modeling runs shown above covered hydrologically, the collective suite of
alternatives that were carried forward for analysis in the EIR. This is because the
alternatives, by definition, can only result in so many permutations of water withdrawal
(or depletion) from the system simulated by the mass balance comparative hydrology that
is captured by ResSim and CALSIM II.
As noted previously, the use of ResSim and CALSIM II modeling output is premised on
a comparative analysis between model runs. Model output is generated showing the
differences between model runs. Each pairing or coupling of model runs provides a level
of hydrologic evaluation that is then correlated to the specific alternatives under review.
ResSim
ResSim model run comparisons used in the EIR are as follows:
Run 1 versus Run 2 – Proposed Project “B” Simulation
Run 1 versus Run 3 – Proposed Project “C” Simulation
Run 1 versus Run 4 – Reduced Project Alternative “B-2” Simulation
Run 1 versus Run 5 – Reduced Project Alternative “C-2” Simulation
Run 1 versus Run 2 – Future Cumulative Condition Simulation
(Same as Proposed Project “B” Simulation)
As there are no anticipated projects or changes in future diversions in the Upper
American River basin that have not already been included in the Settlement Agreement
and made part of the ResSim Base Condition. Accordingly, no ResSim Future
Cumulative Modeling runs were modeled.
CALSIM II
CALSIM II model run comparisons used in the EIR are as follows:
Run 1 versus Run 2 – Proposed Project “A” Simulation
Run 1 versus Run 3 – Proposed Project “B” Simulation
Run 1 versus Run 4 – Reduced Project Alternative “A-2” Simulation
Run 1 versus Run 5 – Reduced Project Alternative “B-2” Simulation
Run 1 versus Run 6 – Future Cumulative Condition Simulation
Run 6 versus Run 7 – Proposed Project Increment under Future Cumulative
Condition
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5.0-29
Each model run represented a specific condition (e.g., Base Condition, proposed project,
etc.). For CEQA analytical purposes, model runs were compared against each other
depending on whether the proposed project or alternatives were being evaluated. The
following identifies which model run(s) were used, in which comparison, for each of the
proposed project and alternative evaluations for both ResSim and CALSIM II analyses.
Proposed Project
ResSim
Run 1 (Base Condition) versus Run 2 (Proposed Project "B")
Run 1 (Base Condition) versus Run 3 (Proposed Project "C")
CALSIM II
Run 1 (Base Condition) versus Run 2 (Proposed Project "A")
Run 1 (Base Condition) versus Run 3 (Proposed Project "B")
Alternative 1
(No modeling was undertaken - Impacts were inferred from the modeling output for
Alternative 2)
Alternative 2
ResSim
Run 1 (Base Condition) versus Run 4 (Reduced Project Alternative "B-2")
Run 1 (Base Condition) versus Run 5 (Reduced Project Alternative "C-2")
CALSIM II
Run 1 (Base Condition) versus Run 4 (Reduced Project Alternative "A-2")
Run 1 (Base Condition) versus Run 5 (Reduced Project Alternative "B-2")
Alternative 3
ResSim
Run 1 (Base Condition) versus Run 2 (Proposed Project "B")
Run 1 (Base Condition) versus Run 3 (Proposed Project "C")
Chapter 5.0 Impact Assessment Methodology
5.0-30
CALSIM II
Run 1 (Base Condition) versus Run 2 (Proposed Project "A")
Run 1 (Base Condition) versus Run 3 (Proposed Project "B")
Alternative 4
ResSim
Run 1 (Base Condition) versus Run 2 (Proposed Project "B")
Run 1 (Base Condition) versus Run 3 (Proposed Project "C")
CALSIM II
Run 1 (Base Condition) versus Run 2 (Proposed Project "A")
Run 1 (Base Condition) versus Run 3 (Proposed Project "B")
Alternative 8
ResSim
Run 1 (Base Condition) versus Run 2 (Proposed Project "B")
Run 1 (Base Condition) versus Run 3 (Proposed Project "C")
CALSIM II
Run 1 (Base Condition) versus Run 2 (Proposed Project "A")
Run 1 (Base Condition) versus Run 3 (Proposed Project "B")
5.2.8 Impact Thresholds – Frequency and Magnitude
CEQA defines a significant effect as a substantial, or potentially substantial, adverse
change in the environment (Public Resources Code § 21068). CEQA (Public Resources
Code § 21083(b)(1)) stipulates that a “significant effect on the environment” could occur
when “[a] proposed project has the potential to degrade the quality of the environment,
curtail the range of the environment, or to achieve short-term, to the disadvantage of
long-term, environmental goals.” Section 15065(a) of the Guidelines Implementing
CEQA (Guidelines Guidelines) directs that additional significant effects on the
environment be found where a “project has the potential to: . . . substantially reduce the
habitat of a fish or wildlife species; cause a fish or wildlife population to drop below self-
sustaining levels,; threaten to eliminate a plant or animal community; substantially
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5.0-31
reduce the number or restrict the range of an endangered, rare or threatened species; or
eliminate important examples of the major periods of California history or prehistory.”
The Guidelines implementing CEQA direct that scientific data and factual data form the
basis for significance determination. The impact discussion in each of the following
subchapters identifies the specific criteria for determining the significance of a particular
impact. The significance criteria are consistent with the intent of the Guidelines
implementing CEQA. The State CEQA Guidelines (§ 15382) recognize a significant
effect on the environment as:
“….substantial, or potentially substantial adverse change in any of the physical
conditions within the area affected by the project including land, air, water, minerals,
flora, fauna, ambient noise, and objects of historic or aesthetic significance. An
economic or social change by itself shall not be considered a significant effect on the
environment. A social or economic change related to a physical change may be
considered in determining whether the physical change is significant.”
Modeling data used to assess potential impacts to water-related resources provided the
opportunity to evaluate effects from both a temporal and severity perspective. The
historic hydrologic record (i.e., 83-years) provided the temporal basis for assessment; that
is, the monthly differences in hydrology between the baseline and the proposed project
(or alternatives) could be viewed over an 83-year period. A review of the entire period of
record facilitated the assessment of how frequent such incursions would be. In any
individual year, the quantitative comparison in modeling output between the baseline and
the proposed project (or alternatives) provided the severity or magnitude of effect. From
this perspective, both magnitude and frequency were important considerations in the
determination of impact significance, as defined by CEQA.
5.3 Non-Diversion-Related Impact Evaluation
As established under CEQA case law, potential secondary (or indirect) impacts
associated with a project are the result of activities and/or conditions in the natural or
man-made environment that would or could arise from full implementation of the
proposed project. These impacts are separate, and distinctive from the direct impacts of
the project. Such indirect effects have been ascribed the “but for” test, that is, their
increment of effect would not occur, but for, the current proposed project. Common
examples of indirect effects include increased traffic, reduced air quality, or increased
soil erosion.
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Indirect or non-diversion related impacts could potentially affect the following resources:
Land Use/Urban Development
Transportation/Traffic
Air Quality
Noise
Geology and Soils
Visual Resources
Terrestrial Resources
Recreational Resources (non-water related)
Cultural Resources (non-water related)
It is typical in water acquisition projects (e.g., new water entitlements), regardless of
type, that the potential indirect effects associated with delivering the water to the
proposed service areas (i.e., intended places of use) as well as the changed conditions
within those areas be addressed in the required CEQA document for the water
acquisition. This increased level of assessment is necessary because, as part of the whole
project (e.g., an important concept in CEQA), a water acquisition project per se, cannot
be limited to looking only at the direct effects (i.e., hydrological) of its action; it must
follow the water supply to its ultimate end user. An environmental analysis that does so
will adequately capture the potential effects of the project in its entirety.
The level of detail, however, with which such indirect effects can, and should be assessed
in water acquisition projects, varies depending on the project. In some projects, there is
ample information on the mechanisms by which a new water supply would be diverted,
conveyed, treated, and ultimately distributed to the end users. In some cases, actual
facility and linear footprints of the conveyance routes (that is, siting locations) are
available. More commonly, however, since water acquisition projects represent only the
first phase of a larger and longer-term water supply planning effort, these secondary
actions (i.e., facilities) are not well defined. In many cases, these secondary actions are
years and, in fact, sometimes as long as a decade or more away from funding, planning,
and environmental review, let alone construction and implementation. In those typical
situations, it is difficult and inappropriate, consistent with CEQA, to speculate on where
and how such infrastructure/facilities would be placed and operated.
As discussed previously, for this EIR, a project-level analysis of the new water
acquisition was performed; that is, a detailed evaluation of the hydrological effects of the
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new water right on all those waterbodies and watercourses potentially affected by the
proposed diversion withdrawals.
At a more general level, indirect or secondary impacts were evaluated and included those
resources categorized as being non-diversion related; that is, they are not part of the
hydrological system. Accordingly, while it is accepted that new diversion, conveyance,
and treatment facilities are not required to grant the new water rights sought by this
project, because of the potential for the future construction of such facilities, the potential
impacts of such facilities, to the extent known, were disclosed and discussed generally at
a program-level.
Using this context, the EIR addressed the areas between the proposed points of new
diversion and the existing service areas of EID and GDPUD, including those delineated
“Favorable Areas” that have been made a part of the proposed intended place of use.
Baseline information that exists today was reviewed and used to evaluate the potential
effects to these non-diversion related resources based on a generalized consideration of
typical construction-related activities for these types of facilities. Reference to existing
General Plan and other County policies, ordinances, and guidelines as well as State
and/or federal agency protocols that govern the practices (e.g., BMPs) of construction-
related activities were made, as appropriate. The EIR acknowledges and provide the
background for future site-specific projects if, or when new infrastructure are proposed;
the EIR also clearly acknowledges that such actions would require separate and
independent environmental reviews of the precise facility features and seek to obtain all
necessary associated permits (e.g., Streambed Alteration Agreement, Encroachment
Permit, Authority to Operate, etc.) at that time.
Accordingly, no linear footprints of facilities are presented for analysis in this EIR.
Moreover, no on-the-ground field surveys were conducted for this EIR.
Within the service areas, a wide range of non-diversion related resources (e.g., land use,
traffic, soils, recreation, utilities, etc.) were assessed, again at this more general level of
evaluation. This assessment included the various facilities, activities, land uses and other
potentially affected resources within the service areas that are typically part of ongoing
development activities within urban and rural areas and are typical of those found within
the EID and GDPUD service areas. Since the current project would be contributing to
these indirect effects, a generalized discussion is warranted.
It is important to note, however, that such activities, land uses, and resources have
already been fully analyzed in the adopted El Dorado County General Plan and EIR,
upon which this EIR relies. No adverse effects to in-county resources or activities would
occur as an indirect result of this current project that was not, or has not been already
examined in the El Dorado County General Plan and EIR, and ensuing amendments.
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This EIR, therefore, only summarizes and discuss those findings. The EIR does not
attempt to fully re-examine the precise impacts of growth on the environment anticipated
to occur as a result of future development County-wide or, even of this project. As noted,
this is because the physical environmental effects of urban development have already
been appropriately evaluated, across all resources, in the El Dorado County General Plan
and accompanying EIR and the various resource programs that have developed since the
adoption of the General Plan. The General Plan and accompanying EIR fulfilled its
requirements under CEQA and serves as the appropriate evaluation of and validation for
anticipated growth-related effects within the County.