WSP03527

• File Number: 822.600.10
• Description: Colorado River Annual Operating Plan - Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/2003
• Author: USDOI/BOR
• Title: Annual Operating Plan
• Water Supply Pro - Doc Type: Annual Report

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requirements. It is likely that Reclamation will allow Senator Wash operations to range between
elc\"ations 242 10 145 feet. However. a review of the CY 2001 test fill data will be required before
operations will be allowed to exceed elevation 240 feet. Through August 2002. approximately
l05A60 acre-fect had been over delivered 10 .\-lexica in C'{ 2002.

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Laguna Reservoir is a regulating storage facility located approximately 7 river miles downstream of
Senator Wash. Operational objectives are similar to those for Senator Wash Reseryoir. The storage
capability of Laguna Reservoir has diminished from about 1.500 acre-feet to about 600 acre-feet due
to sediment accumulation and vegetation growth. Sediment accumulation in the reservoir has
occurred primarily due to flood releases that occurred in 1983 and 1984. and flood control or space
building releases that occurred between 1985 and 1988 and from 1997 through 1999. Dredging of
the Laguna Reservoir 10 increase its storage capability to contain sluicing operations at Imperial Dam
is scheduled to begin in CY 2004.

Imperial Dam

Imperial Dam is the last diversion dam on the Colorado River for United States water users. From
the head works at Imperial Dam the diversions of flows for American water users and t\lexico occur
into the All American Canal on the California side. and into the Gila Gravity Main Canal on the
Arizona side of the dam. These diversions supply all the irrigation districts in the )'uma area. in
Welllon-Mohawk. in the Imperial and Coachella Valleys. and through Pilot Knob to NIB to the
Mexicali Valley in !\.1exico. The diversions also supply much of the domestic and industrial water
needs in the Yuma area.

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Yuma Desalting Plant

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The Yuma Desalting Plant (YDP) was not operated in CY 2002 and is in a ready reserve status. In
calendar year 200t the amount of water discharged through the ".-Jain Outlet Drain was 107.910 acre-
feet. The U.S. recognizes that it has an obligation to replace. as appropriate. the bypass flows.
Reclamation is preparing a report for Congress that explores options for replacement of the bypass
flows from Welllon-Mohawk. including options that would not require operation of the Yuma
Desalting Plant. Operation of the YDP would affect the Cienega de Santa Clara. a marsh of
approximately 10,000 acres that is a protected environmental area in lvlexico.

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The Main Outlet Drain and Main Outlet Drain Extension (!\.10DE) requires minor repair work each
year. and a short section of the MODE near the contluence with the Gila River that was damaged
during the 1993 Gila River flood still needs to be repaired. However. seepage from the drain is less
than one percent of the ground water flow in the area and is not significantly affecting the quality of
the ~'Tound waleror the Colorado River water. .7\'linor repair work accomplished each year consists of
replacing isolated broken concrete panels and cleaning debris from the drainage system. In t\1arch
2002. some drainage water was spilled from the .\IODE to the Colorado Riverto accommodate panel
replacement along much of the ~10DE. AIJ \\'ellton.~1ohawk Irrigation & Drainage District
drainage flows are expected to be contained in the ,\10DE for the rest of CY 2002 to prevent
increasing the salinity of the Colorado River arriving at the Northerly International Boundary (NIB)
with "1exico.

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December 13. 2002

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