WSP05551

• File Number: 822.600.10
• Description: Colorado River Annual Operating Plan - Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/2002
• Author: USDOI/BOR
• Title: Annual Operating Plan
• Water Supply Pro - Doc Type: Annual Report

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Mohave and Havasu Reservoirs are scheduled to be drawn down in the late summer and v.inter
months to pro\-ide storage space for local storm runoff and will be filled in the spring to meet
higher summer water needs. This drawdown will also correspond with maintenance at both Davis
and Parker powerplants which is scheduled for September through February, During 2002, Lake
Mohave will continue to be operated under the constraints as described in the Biological and
Conference Opinion on Lower Colorado River Operations and Maintenance. Reclamation, as
provided in the Interim Surplus Guidelines Record of Decision, will continue these existing
operations in Lake !\lohave that benefit native fish through the effective period of the Interim
Surplus Guidelines and will explore additional ways to provide benefits to native fish. The normal
filling pattern of these two reservoirs coincides well with the fishery spawning period. Since lake
elevations will be typical of previous years, normal conditions are expected for boating and other
recreational uses,

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Reclamation is the lead agency in the Native Fish Work Group, a multi-agency group ofscientists
attempting to augment the aging stock of the endangered razorback sucker in Lake Mohave.
Larval suckers are captured by hand in and around spawning areas in late winter and early spring
for rearing at Willow Beach Fish Hatchery below Hoover Dam. The following year, one year old
suckers are placed into predator-free, lake-side backwaters for rearing through the spring and
summer. When the lake is normally drawn down during the fall, these fish are harvested from
these rearing areas and then released to the lake. The suckers grow very quickly, usually
exceeding ten inches in length by September.

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Senalor Wash and Laguna Reservoirs

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Operations at Senator Wash Reservoir allow regulation of water deliveries to United States and
~1exican water users downstream at Imperial Dam. The reservoir is utilized as an off-stream
storage facility to meet downstream water demands and to conserve water for future uses in the
United States and the scheduled uses of Mexico in accordance with the Treaty obligation.
Senator Wash Reservoir is the first storage facility below Parker Dam. Senator Wash Dam is
located approximately lol2 river miles downstream of Parker Dam. Operational objectives are
to store excess flows from the river which have been caused by water user cutbacks and sidewash
inflows due to rain. Stored waters are utilized to meet irrigation. recreational. and Treaty
demands. Elevation restrictions on Senator Wash Reservoir reduce the flexibility of water storage
in the lower reaches of the river. An elevation restriction of 240.0 feet at Senator Wash
Reservoir, due to potential piping at West Squaw Lake Dike and Senator Wash Dam, had been
in place, A test-fill occurred September 15 to October 19,2000 and had to be stopped due to
piping concerns at West Squaw Lake Dike. Since the test-fill a new elevation restriction has
temporarily decreased the storage elevation to 235 feet. with normal operations ranging from 218
to 233 feet Data from this initial test-fill have been analyzed. Hydrologic analysis indicates the
best time of year to do the restoration is from ~'1arch to July, to reduce excess administrative
deliveries, The earliest the restoration and subsequent test fill could occur is March 2002.

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Laguna Reservoir is a regulating storage facility located approximately 7 river miles downstream
of Senator Wash. Operational objecti\-.es are similar to those for Senator Wash Reservoir. The

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October 15, 200 1

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