WSP01193

• File Number: 8278.400
• Description: Title I - Mexican Treaty and Minute 242
• Basin: Colorado Mainstem
• Date: 1/1/1973
• Author: IBWC
• Title: Minute 242 Annual Report
• Water Supply Pro - Doc Type: Annual Report

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REPORT ON OPERATIONS
FOR SOLUTION OF THE COLORADO RIVER
SALINITY PROBLEM UNDER MINUTE NO. 241

This report presents the results of operations carried out under the
agreement with Mexico entitled "Recommendations to Improve Immediately
the Quality of Colorado River Waters Going to Mexic~' referred to as
Minute No. 241 of this Commission, signed on July 14, 1972. This ~tinute
was originally for the period July 1, 1972 through December 31, 1972, and
was extended three times by exchange of Notes, so that it was in effect
for a total of 14 months.

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The agreement was reached pursuant to the understanding between President
Nixon and President Echeverria, expressed in their Joint Communique of
June 17, 1972, that the United States would "undertake certain actions
immediately to improve the quality of water going to Mexico."

PERTINENT PROVISIONS OF MINUTE NO. 241

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The agreement provided that the United States would, commencing on the
date of its approval, discharge to the Colorado River downstream from
Morelos Dam volumes of drainage waters from the Well ton-Mohawk District
at the annual rate of 118,000 acre-feet and substitute therefor equal
volumes of other waters of better quality to be discharged to the Colorado
River above Noreios Dam, which it was estimated would reduce the salinity
of such waters by at least 100 parts per million as an annual mean, compared
with the mean annual salinity of the waters made available to Mexico at the
Northerly International Boundary in the calendar year 1971, under Minute
No. 218, which was 1242 parts per million. The attached map, Exhibit 1,
shows the area and locations referred to.

UNITED STATES OPERATIONS

Basic data for analyses of operations under Minute No. 241 are the records
of flows and salinities secured by the U.S. Section, International Boundary
and Water Commission, the Bureau of Reclamo.ti.on, and the Geologic Survey.
These data show that United States operations complied with the provisions
of Minute No. 241: The United States discharged to the river channel below
Morelos Dam, during the 12 month period July 1972 through June 1973, a total
of 119,490 acre-feet of Wellton-Mohawk drainage and substituted better
waters therefor from above Imperial Dam (60,930 acre-feet) and from the
Yuma Mesa Hells (58,560 acre-feet). These measures resulted in a mean annual
salinity of Colorado River treaty waters made available to Mexico at the
Northerly International Boundary of 1140 parts per million, a reduction of
102 parts per million from the mean annual salinity of 1242 parts per million
at the same location during the calendar year 1971 under ~linute No. 218.

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