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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III. PROJECT PLAN

Minute No. 242 provides that, subject to authorization by the
Congress and the appropriation of f'unds for the necessary work, not
earlier than Janus.ry 1, 1974, s.r.d not later than July 1, 1914, the
United States will take measures to assure that the waters delivered
to Mexico upstream from Morelos Dam will have an annual average salinity
of no more than 115 ppm + 30 ppn TDS greater than the annual average
salinity of Colorado River waters arriving at Imperial Dam.

From September 1, 1913, until Congress authorizes appropriations
for the necessary works, the United States shall discharge to the
Colorado River downstream from Morelos Dam volumes of drainage waters
from the Wellton-Mohawk District at the annual rate of 118,000 acre-
feet and substitute therefor an equal volume of other water to be
discharged to the Co10rado River above Morelos Dam.

After January 1, 1974, or the authorization by the Congress,
whichever ccmes later and until the necessary measures under the per-
manent solution are completed, the United States will have to bypass
al.l of the Wellton-Mohawk drainage and replace it with water of
Imperial Dam qualf.ty to maintain the differential.

Permanent and interim measures necessary to meet the commitment
under Minute No. 242 are described in subsequent paragraphs of this
Executive Summary. Project features are identified on Plate 1.

A. Measures to Maintain a Salinity Differential

Studies indicate that with no Well ton-Mohawk drainage included in
the waters delivered to Mexico at the Northerly International Boundary,
the salinity will be 115 ppm + 30 ppm TDS greater than the salinity of
waters arriving at Imperial Dam. This is the differential specified in
Minute No. 242, and it can be achieved in two ways. The first is to
exclude al.l Wellton-MOhawk drainage from the waters delivered to Mexico
and to rep1ace them with waters from above Imperial Dam. The other is
to treat the drainage waters so they will have the same salinity as
waters from above Imperial Dam.

To exclude the drainage waters from the waters delivered to Mexico
as a part of the Treaty deliveries, it would be necessary to eliminate
irrigation operations in the Wellton-Mohawk Division of the Gila Project
or to bypass all its drainage waters around Mexico I s point of diversion.
To shut dawn the We11ton-Mohawk Division of the Gila Project is not
considered economically or politically viable. To bypass all of the
Wellton-Mohawk drainage waters would entail the loss of from 175,000
to 220,000 acre-feet annually from the Colorado River System, a prospect
wholly unacceptable to the Colorado River Basin States and one that is
not considered further as an alternative.

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