WSP05341

• File Number: 8278.100
• Description: Title I - Yuma Desalting Plant
• Basin: Colorado Mainstem
• Date: 12/23/1992
• Author: USDOI/BOR
• Title: Yuma Desalting Plant - Alternatives for the Interim Period
• Water Supply Pro - Doc Type: Publication

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B A C K G R 0 U N D

INTRODUCTION

PURPOSE

The purpose of this report is to evaluate the merits of operating the
Yuma Desalting Plant (Desalting Plant), examine alternatives, and make a
recommendation as to the Preferred Plan of Action for the remainder of
the interim period. The Desalting Plant, the Bypass Drain to the Santa
Clara Slough (Slough), and the concrete lining of the Coachella Canal
are integral features of the works authorized by the Colorado River
Basin Salinity Control Act of 1974 (Public Law 93-320) (1974 Act).
Operation of the Desalting Plant will allow poor quality drainage water
from the Wellton-Mohawk Irrigation and Drainage District (WMIDD) to be
conserved, returned to the Colorado River, and used to meet the United
States commitments to the 1944 Water Treaty (1944 Treaty) with Mexico
for the delivery of water to Mexico.

Currently, the drainage water is not returned to the river but
discharged to the Slough via the Bypass Drain as a temporary means of
reducing salinity levels in the river to meet the Colorado River
salinity obligation to Mexico under Minute No. 242 of the International
Boundary and Water Commission (Minute No. 242). The United States has
the temporary use of about 132,000 acre-feet (af) per year of conserved
water supplies developed by lining the Coachella Canal to offset the
impact on reservoir storage of providing additional releases, in lieu of
using WMIDD drainage return flow, to meet the 1944 Treaty with Mexico.

This temporary supply of conserved water was originally intended to be
used during an interim period while the Desalting Plant was under
construction and while Colorado River water use in the Lower Colorado
River Basin (Lower Basin) continued to be less than apportioned
supplies. While construction of the Desalting Plant is now complete,
water use in the Lower Basin continues to be less than the apportioned
supply, and the interim period is expected to extend for at least a few
more years and possibly longer.

BACKGROUND AND SCOPE

The 1974 Act authorized and directed the Secretary of the Interior
(Secretary) to proceed with a program of works to enhance and protect
the quality of water available in the Colorado River for use in the
United States and Mexico and to enable the United States to comply with
its obligations under Minute No. 242 without depriving the seven
Colorado River Basin States (Basin States) of any of their apPQrtioned
Colorado River water supply. Minute No. 242 is considered an extension
of the 1944 Treaty with Mexico, which addresses the salinity of the
Colorado River water delivered to Mexico.

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