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FINAL Supplemental
EIS/EIR
Acquisition of
Additional Water for Meeting the San Joaquin River
Agreement Flow Objectives, 2000 – 2010
11. ENERGY PRODUCTION
Index
11.1 AFFECTED ENVIRONMENT
Energy resources in the Project Area consist of
hydroelectric power generation. Hydroelectric power
generation plants provide approximately 24 percent
of California’s electrical generation capacity.
The Central Valley Project (CVP) hydropower system
provides a significant portion of the available
energy to the San Joaquin Valley. The CVP system
of power plants and pumping plants has an installed
capacity of 749 megawatts (MW). Most of the power
that is generated from the CVP system is used to
operate CVP pumping plants or is sold to public
agencies.
The major storage reservoirs that supply water
for hydroelectric power generation located in the
Project Area are New Don Pedro Reservoir and Lake
McClure. Hydroelectric power generation facilities
located downstream of these reservoirs include the
New Don Pedro Project located on the Tuolumne River
and the Exchequer, McSwain, and Merced Falls projects
located on the Merced River.
11.1.1 New Don Pedro Project
The New Don Pedro Project (NDPP) is located at
the western edge of Tuolumne County on the Tuolumne
River. It is owned and operated jointly by Modesto
Irrigation District (MID) and Turlock Irrigation
District (TID). The NDPP consists of the New Don
Pedro Dam, New Don Pedro Reservoir, and the New
Don Pedro Powerhouse (FERC 1996). In addition to
providing water, flood control, and recreational
opportunities, the NDPP system produces hydropower.
The system has four dams and associated powerhouses,
as described in Table 11-1. MID and TID own 31.54
percent and 68.46 percent, respectively, of the
New Don Pedro hydroelectric plant. This equates
to approximately 63 and 136.2 MW, respectively,
of the power produced.
Table
11-1
Hydroelectric Power Facilities Located on the Lower
Tuolumne River
Reservoir operations at NDPP are controlled by
various agreements between the City and County of
San Francisco, MID and TID, the U.S. Army Corps
of Engineers, and California Department of Fish
and Game as well as Federal Energy Regulatory Commission
license articles. The NDPP has a minimum flow requirements
schedule below New Don Pedro Dam to protect fishery
resources.
11.1.2 Exchequer, McSwain,
and Merced Falls Projects
The Exchequer, McSwain, and Merced Falls projects
(Table 11-2) are located downstream of Lake McClure
on the Merced River in Mariposa County. The Exchequer
and McSwain projects are owned and operated by Merced
Irrigation District. The Merced Falls Project is
owned by Pacific Gas & Electric Company. Both
the Exchequer and McSwain projects include storage
facilities, but the Merced Falls Project does not.
Table
11-2
Hydroelectric Power Facilities Located on the Lower
Merced River
11.2 ENVIRONMENTAL CONSEQUENCES
AND MITIGATION MEASURES
The production of electricity from falling water
is a significant source of energy in the Project
Area. Major factors that influence hydrogeneration
operations include reservoir storage and upstream
water regulation and supply, downstream water needs,
applicable license and permit requirements, and
electricity demand (which fluctuates according to
the time of the year, weather conditions, and the
economics of the energy market). Releases from upstream
reservoirs are dependent on not only upstream water
sources (principally from snow melt), and the nature
and extent of droughts, but also electricity demand,
water rights agreements, other water supply contracts,
and minimum downstream streamflow requirements.
11.2.1 Key Impact Issues and
Evaluation Criteria
This section of the SEIS/EIR examines the issues
associated with potential power production from
reservoir releases to meet the Project purpose.
Power consumption from activities such as pumping
are not addressed in this SEIS/EIR because the Proposed
Action does not call for a significant amount of
pumping of water over what already occurs under
existing conditions to deliver surface water and
groundwater. There is no potential for indirect
impacts to groundwater pumping to occur. The key
issue is to what extent the early release of water
(to meet Project objectives) would affect hydroelectric
power production.
Hydroelectric generation projects depend upon an
upstream water source, such as a storage reservoir
and the change in elevation between the source and
the discharge point. The electricity is generated
in the powerhouse, which may be located at the base
of the dam forming the reservoir or farther downstream.
The amount of energy generated directly depends
upon both the amount of water run through the powerhouse
turbines and on the difference in elevation between
the water in the reservoir and the powerhouse. Thus,
the higher the elevation of the water in the storage
reservoir, the greater the potential for power production.
Power produced during the peak energy demand period
is more valuable than that produced during lower
demand periods. Hydropower is an energy source that
can be turned on and off quickly, and is therefore
employed to meet peak loads when possible. In California,
these peak loads typically occur in the summer when
maximum groundwater pumping, industrial, and air
conditioning demands occur. Reductions in a hydroelectric
plant’s ability to meet peak load requirements
accelerates the need for additional peaking resources
and increases utility costs (McCann 1994, cited
in State Board 1998).
11.2.2 Environmental Consequences
The Proposed Action would result in higher flows
in April or May in some years than would occur under
the No Action Alternative. The model estimates that
supplemental water would come entirely from either
New Don Pedro Reservoir or Lake McClure; in reality,
the water could come from either one reservoir or
the other or a combination of both, up to 47,000
acre-feet total. The model results show that achieving
these flows requires a shift in reservoir operation
that includes "borrowing" from storage
to make these spring releases and "paying back"
the borrowed water during some future winter or
spring months when water in excess of present commitments
is available.
The projected reservoir storage capacity and flow
figures were obtained from the hydrologic model
results, contained in Appendix A. Of concern to
the energy impact analyses is the fact that the
model results include the New Melones Interim Plan
of Operation (Reclamation 1997b), which has been
in effect for over 2 years.
11.2.2.1 Proposed Action on the Tuolumne River
The changes in water storage based on the Proposed
Project from the No Action Alternative were determined
for both the April and May model results, as reported
in Appendix A. In the supplemental Hydrologic Analysis
(Appendix A), the model results indicate that Proposed
Project releases would only occur during approximately
10 percent of the years during the modeled period
of 1922 through 1992. The additional releases would
range from 2,000 acre-feet to 46,000 acre-feet during
those years affected by the Proposed Project.
New Don Pedro Reservoir
An elevation difference was calculated from the
difference in storage for New Don Pedro Reservoir
during those months affected by the supplementary
Vernalis Adaptive Management Plan (VAMP) releases.
The energy production (GWh) was calculated using
values provided by TID that related kilowatt-hours
per acre-foot for each foot of reservoir elevation.
No Action. The No Action Alternative represents
current conditions. The average annual generation
for the New Don Pedro power plant is 618 GWh. The
average annual generation for the entire state of
California in 1995 was a total of 51,660 GWh. In
other words, the New Don Pedro plant produces approximately
1.2 percent of the state’s total power.
Proposed Action. The Proposed Action would
result in changes in calculated energy production
from the No Action Alternative as follows:
- Supplementary VAMP Release: During the months
with a supplemental VAMP release, energy production
would increase (up to the capacity of the New
Don Pedro and La Grange Auxiliary powerhouses)
as more water is made available for generation.
The Turlock Lake and Stone Drop powerhouses would
be unaffected because no change in flow or head
would result from the supplementary VAMP release
at these facilities.
- Head Effects: During the months following a
supplemental VAMP release, energy production at
New Don Pedro Powerhouse would decrease because
of the reduced reservoir elevation. No other generating
facilities would be impacted.
- Replacement of Supplementary VAMP Releases:
During months when runoff is available such that
New Don Pedro Reservoir can be refilled, energy
production at New Don Pedro Reservoir and La Grange
Auxiliary powerhouses would decrease (typically
during periods when in the absence of supplementary
VAMP, releases would be made to prevent encroachment
into the flood control pool).
The net results for the New Don Pedro Powerhouse
for the years affected are presented in Table 11-3
assuming an April supplemental VAMP release, and
Table 11-4 assuming a May supplemental VAMP release.
These results show a total net loss of generation
of 22 GWh (May releases) and 26 GWh (April releases)
over the 71 years studied, or if equated to an annual
basis, a loss of 0.31 and 0.36 GWh/year. This
is approximately 0.05 percent of the average annual
generation at this facility. This potential
loss in generation translates into an average loss
of supply for 400 to 500 homes for 1 month. Given
that the current energy situation in California
affects the entire state, these values would be
considered insignificant when compared to California’s
total housing units that number over 10.3 million
(Gaquin and Littman 2000). This change in energy
production is considered insignificant in terms
of effects on the California energy market. The
monetary loss to the reservoir owners due to the
decreased energy production could be offset in some
years by the sale of the supplemental water, and
is therefore considered insignificant.
Detailed calculations were not performed for the
La Grange Auxiliary Powerhouse. By inspection the
impacts were determined to be insignificant because
of the relative size of La Grange compared to New
Don Pedro, and because there are no decreased head
elevation effects at LaGrange.
11.2.2.2 Proposed Action on the Merced River
The changes in water storage based on the Proposed
Project from the No Action Alternative were determined
for both the April and May model results, as reported
in Appendix A. In the supplemental Hydrologic Analysis
(Appendix A), the model results indicate that Proposed
Project releases would only occur during approximately
10 percent of the years during the modeled period
of 1922 through 1992. The additional releases would
range from 2,000 acre-feet to 46,000 acre-feet.
Table
11-3
Change in Energy Production for New Don Pedro Reservoir
with April Releases, Affected Months Only
Lake McClure
An elevation difference was calculated from the
difference in storage for Lake McClure during those
months affected by the supplemental VAMP releases.
The energy production (GWh) was estimated for Lake
McClure using values developed by URS based on the
procedure provided by TID for New Don Pedro Reservoir
relating kilowatt-hours per acre-foot for each foot
of reservoir elevation.
No Action. The No Action Alternative represents
current conditions. The average annual generation
for the Exchequer Power Plant is 316 GWh. The average
annual generation for the entire state of California
in 1995 was a total of 51,660 GWh. In other words,
the Exchequer Plant produces less than one percent
of the state’s total power.
Proposed Action. The Proposed Action would
result in changes in calculated energy production
from the No Action Alternative as follows:
- Supplementary VAMP Release: During the months
with a supplemental VAMP release, energy production
would increase (up to the capacity of the Exchequer,
McSwain, and Merced Falls powerhouse) as more
water is made available for generation. Due to
limitations on the Exchequer generator capacity,
supplemental VAMP releases in May would often
result in no increase in energy production.)
Table
11-4
Change in Energy Production for New Don Pedro Reservoir
with May Releases, Affected Months Only
- Head Effects: During the months following a
supplemental VAMP release, energy production at
Exchequer would decrease because of the reduced
reservoir elevation. No other generating facilities
would be imported.
- Replacement of Supplementary VAMP Releases:
During months when runoff is available such that
Lake McClure can be refilled, energy production
of Exchequer, McSwain, and Merced Falls powerhouses
would decrease (typically during periods when
in the absence of supplementary VAMP, releases
would be made to prevent encroachment into the
flood control pool).
The net results for the Exchequer Powerhouse for
the years affected are presented in Table 11-5,
assuming an April supplemental VAMP release and
Table 11-6, assuming a May supplemental VAMP release.
These results show a total net loss of generation
of 19 GWh (May releases) and 78 GWh (April releases)
over the 71 years studied (for both April and May
releases), or if equated on an annual basis, a loss
of 0.26 GWh and 1.10 GWh/year. This is an average
of approximately 0.21 percent of the average annual
generation at this facility. This potential
loss in generation translates into an average loss
of supply for 350 to 1,500 homes for 1 month. Given
that the current energy situation in California
affects the entire state, these values would be
considered insignificant when compared to California’s
total housing units that number over 10.3 million
(Gaquin and Littman 2000). This change in
energy production is considered insignificant in
terms of effects on the California energy market.
The monetary loss to the reservoir owners due to
the decreased energy production could be offset
in some years by the sale of the supplemental water
and is, therefore, considered insignificant.
Table
11-5
Change in Energy Production for Exchequer (Lake
McClure) with April Releases, Affected Months Only
Detailed calculations were not performed for the
McSwain and Merced Falls powerhouse. By inspection,
the impacts were determined to be insignificant
because of the relative size of these facilities
compared to Exchequer, because of the changes in
flow offset and because there are no decreased reservoir
elevation effects at McSwain and Merced falls.
11.2.3 Impact Summary and Mitigation
of Impacts
- If the supplemental water was released entirely
from New Don Pedro Reservoir, the net loss in
generation from the New Don Pedro Power Plant
would be between 22 GWh and 26 GWh over the model
study period, or from 0.31 GWh/year to 0.36 GWh/year.
This change in energy production is considered
insignificant, and no mitigation is necessary.
- If the supplemental water was released entirely
from Lake McClure, the net loss in generation
from the Exchequer Powerhouse would be between
19 GWh and 78 GWh over the model study period,
or from 0.26 GWh/year to 1.10 GWh/year. This change
in energy production is considered insignificant,
and no mitigation is necessary.
- Impacts at the smaller downstream powerhouses
were determined by inspection to be insignificant,
with minor increases possible during periods of
supplemental VAMP release offset by decreases
during periods when storage in replaced in the
upstream reservoir(s).
Table
11-6
Change in Energy Production for Exchequer (Lake
McClure) with May Releases, Affected Months Only
Final SEIS/EIR
CH 11 |
March 13, 2001
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