WSP09883

• File Number: 8273.100
• Description: Colorado River Basin Salinity Control - Federal Agency Reports - BOR
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 9/1/1973
• Title: Colorado River International Salinity Control Project - Special Report - Executive Summary
• Water Supply Pro - Doc Type: Report/Study

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Therefore, the only method acceptable to United States interests
is to treat the Wellton-Mohawk drainage waters so that they will have
the same salinity as waters from above Imperial Dam. This can be done
by constructing a complex to desalt a portion of the drainage and
blending the product water with remaining drainage to achieve the desired
salinity. The reject stream from the plant, amounting to between 40,000
and 50,000 acre-feet per year, will constitute a loss of water from the
Colorado River System, but it may be reduced by increased efficiency of
operations.

1. Permanent Measures. This Project Plan considers the desalting
of a portion of Wellton-Mohawk drainage to be the only viable method of
achieving the salinity differential as a permanent solution to the
Colorado River International salinity problem. The facilities and
activities required to treat the Well ton-Mohawk drainage are hereinafter
referred to as the Desalting Complex, and consist of structural and non-
structural measures.

Because the size of the desalting plant depends upon the quantity
of the drainage waters, studies were made to determine if the quantity
of the Wellton-Mohawk drainage waters might be reduced and to determine
the quality of the feed water.

The studies indicate that a combination of improved irrigation
efficiencies and a reduction in irrigated area can reduce the drainage
from the Wellton-Mohawk Division to about 175,000 acre-feet per year.

The Desalting Complex comprises the desalting plant facilities
within the plant boundary and other associated facilities. The desalting
plant facilities within the plant boundary include the pretreatment plant,
the desalting plant, and appurtenant works. other associated facilities
include a bypass drain, Main Outlet Drain Extension siphon, an irrigation
efficiency improvement program, acreage reduction and/or onfarm irrigation
system improvements, and Gila River control measures below Painted Rock Dam.

Painted Rock Dam is a Corps of Engineers flood control facility
on the Gila River, some 50 miles upstream from the Wellton-Hohawk area.

2. Interim Measures. Until the Desalting Complex is in operation,
the United States has agreed to take certain measures to reduce the salinity
of waters delivered to Mexico upstream from Morelos Dam. These interim
measures are divided into two time periods: (1) The period following the
signing of Minute No. 242 to the authorization by the United States Congress
and appropriation of :funds to implement the measures, and (2) the period
following the authorization to the operation of the Desalting Complex.

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