WSP06051

• File Number: 8278.400
• Description: Title I - Mexican Treaty and Minute 242
• Basin: Colorado Mainstem
• Date: 1/1/1977
• Author: IBWC
• Title: Minute 242 Annual Report
• Water Supply Pro - Doc Type: Annual Report

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A REPORT ON OPERATIONS FOR THE
SOLUTION OF THE INTERNATIONAL PROBLEM OF THE SALINITY
OF THE COLORADO RIVER UNDER MINUTE NO. 242
FOR THE PERIOD

January 1, 1977 - December 31, 1977

This report presents the results of operations under the agreement incor-
porated in Minute No. 242 dated August 30, 1973, of the International
Boundary and Water Cormnission, United States and Mexico, entitled "Perma-
nent and Definitive Solution to the International Problem of the Salinity
of the Colorado River." The operations began on June 25, 1974, immediately
following approval of the Enabling Legislation, Public Law 93-320. This
report describes operations during the third full calendar year from
January 1, 1977, through December 31, 1977.

This report .is based upon the records of flows and salinities secured
jointly by the United States. and Mexican Sections of the International
Boundary and Water Cormnission, the U.S. Bureau of Reclamation, and the
U.S. Geological Survey. Locations and features referred to in this report
are shown on the map Exhibit 1.

The records show that the United States operations were in compliance with
the agreement in Minute No. 242.

The Salinity Differential

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Minute No. 242 provides in Point 1 that:

"The United States shall adopt measures to assure that . . . the
approximately 1,360,000 acre-feet (1,677,545,000 cubic meters)
delivered to Mexico upstream of Morelos Dam, have an annual average
salinity of no more than 115 ppm + 30 ppm U.S. count (121 ppm +
30 ppm Mexican count) over the an;ual average salinity of Colorado
River waters which arrive at Imperial Dam. . ."

The records show that during the calendar year 1977:

1) Colorado River water deliveries to Mexico upstream of Morelos Dam
amounted to: 1,478,823 acre-feet (1,824,114,000 cubic meters).

2)

The average salinities of the waters a)
Morelos Dam and b) arriving at Imperial
ity differentials were as follows:

delivered to Mexico upstream of
Dam and c) the resulting salin-

\Vaters

a) Delivered to Mexico upstream of
Morelos Dam

Total Dissolved Solids in prm 1/

1977
Nexican
Count

U.S.
Count

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b) Arriving at Imperial Dam

c) Salinity Differential
1/ The-differences in U.S. count
diff;rent .methods of analyses and of
by each country's laboratory.

943
820
123

987
862
125

and Mexican count are due to use of
computing the total dissolved solids,