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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storage capability of Laguna Reservoir is currently diminished due to sediment accumulation and
vegetation growth. Sediment accumulation in the reservoir has occurred primarily due to
flooding that occurred in 1983 and 1984. Dredging of the Laguna Reservoir to increase its
storage capability is scheduled to begin in water year 2002.

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Imperial Darn

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Imperial Dam is the last diversion dam on the Colorado River for United States water users. From
its head works flow the diversions into the All American Canal on the California side, and into the
Gila Gravity Main Canal on the Arizona side. These diversions supply all the irrigation districts
in the Yuma area and in the Wellton-Mohawk, Imperial, and Caachella Valleys.

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Yuma Desalling Plant

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The Yuma Desalting Plant (YOP) was not operated in 200 I. The U.S. recognizes that it has an
obligation to replace, as appropriate, the bypass flows. The U.S. is exploring options for
replacement of the bypass flows, including options that would not require operation of the Yuma
Desalting Plant.

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Most of the damage to the YDP's associated facilities caused by the 1993 Gila River flood has
been repaired. Those associated facilities are the Main Outlet Drain (MOD), the Main Outlet
Drain Extension (MODE), and the Bypass Drain, which extends from the YOP to the Cienega
de Santa Clara on the coast of the Sea of Cortez. The first half mile section of the MODE was
damaged during the 1993 Gila River flood, This section is operable and the damage is not
atTecting the operation of the MODE or YOP. This section has not been repaired to date because
of the high costs involved associated with dewatering the area. Seepage from the drain is less
than one percent of the ground water flow in the area and is not affecting the quality of the
ground water. Since the 1993 flood, a levee has been built between the MODE and the Gila
River chaMel to direct flood flows away from the damaged area. ?\.tinor repair work is
accomplished each year to replace isolated, broken panels and to clean debris from the drain
system. At this time, repair for the first half mile reach of the MODE has not been included in
any future budgets, All Wellton-?\1ohawk Irrigation & Drainage District drainage flows are
expected to be diverted into the ?\.-100E in 2002. There is a potential that a portion of the
drainage return flows may be diverted to the Colorado River during short periods while repairs
to the MODE and Bypass Drain are being made. These releases are not expected to impact
meeting the requirements of the salinity differential of Minute 242 of the International Boundary
and Water Commission (IBWC).

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The Water Quality Improvement Center (WQIC) processes about one million gallons per day of
drainage water, delivered either from the MODE, pumped from an on-site well, or diverted from
the Cooper Lateral. The water is used for Reclamation facilities, including the WQIC, education
center and administrative offices. The WQIC will continue to operate during calendar year 2002.
An Education Center affiliated ....ith the WQIC was constructed during 1999 and currently otTers

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October 15, 2001

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