WSP07975

• File Number: 8278.100
• Description: Title I - Yuma Desalting Plant
• Basin: Colorado Mainstem
• Date: 10/1/1987
• Author: USDOI/BOR
• Title: Yuma Desalting Plant Operations Study - Draft Special Report
• Water Supply Pro - Doc Type: Publication

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EXECUTIVE SUMMARY

PURPOSE

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This special report documents the identification and the
evaluation of plans that might reduce the cost of operating the
Yuma Desalting Plant (YDP), located adjacent to the Colorado
River in the southwestern corner of Arizona (see Frontispiece)
A series of future activities is also recommended.

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BACKGROUND

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In accordance with a 1944 treaty between the United States and
Mexico, the United States is obligated to deliver 1,500,000
acre-feet of Colorado River water to Mexico each year. During
the 1960's, the quality of the water delivered to Mexico became
so poor that Mexico filed a formal protest. A ~pecial commission
on Colorado River quality was established in 1973, headed by
former ambassador Herbert Brownell. As a result, Minute No. 242
(Minute) of the International Boundary and Water Commission
(IBWC) was adopted. The Minute requires that the United States
ensure that the water arriving at Morelos Dam will have an
average annual salinity of no more than 115 (i30) parts per
million (p.'m) over the average annual salinity of water arriving
at Imperial Dam. The YDP was conceived by the United States as a
permanent solution to meet the provisions of the Minute. The
water is used in Mexico for irrigation in the Mexicali Valley.

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Construction of the YDP was authorized by Public Law 93-320,
Title I, signed June 24, 1974 (as amended by Public Law 96-336)
Construction began in 1975, and at this time the last major
construction contract is about half complete. Title II of the
same act provides for salinity control projects elsewhere in the
Colorado River Basin (which includes the Upper and Lower Basins).

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The purpose of the YDP is to save water for beneficial use while
desalting sufficient drainage returns from the Wellton
Irrigation and Drainage District (Wellton-Mohawk) in Californi ,
to maintain salinity levels at Morelos Dam on the Color 0 River
as specified by the Minute.

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Since the YDP's inception, conditions on the river have changed.
In the past 5 years, high flow conditions have improved the
quality of the water arriving at Imperial Dam, and then delivered
to Mexico. During years of excess flows on the Colorado Riverf
drainage water may bypass the YDP and desalting is not necessary
to meet the water quality requirement of the Minute.

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Annual operation, maintenance, and replacement (OM&R) costs,
including energy to run the YDP, are projected to be in e~cess of
$25 million during years of full YDP operation. These costs have
more than doubled since the project was authorized. Costs are
about $3 to $5 million during years when the YDP is in standby
status and no production is required.

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