FROM:
-UPPER COLORADO RIVER COMMISSION
355 South Fourth East StrutSalt Lau C,g, UtaJi 8411 ! July 25, 19 72
MEMORANDUM
Upper Colorado River Commissioners, Members of Engineering and Legal Committees, et al.
!val V. Goslin, Executive Director
SUBJECT: Agreement for Improvement of Colorado River Water Delivered to Mexico.
According to a joint news release of the Department of State and the Department of the Interior, the United States and Mexico have approved an agreement providing for immediate improvement in the quality of Colorado River water delivered to Mexico. It is believed that this agreement will result in an estimated average annual reduction of at least 100 parts per million of dissolved salts as compared to 19 71.
The agreement, called Minute No. 241 of the International Boundary and Water Commission, was signed on July 14th. It became operative through December 31, 19 72.
Under Minute No. 24-1 the Y-nited States will discharge drainage waters from the Wellton-Mohawk Project in Arizona to the Colorado River below Morelos Dam at the rate of 118,000 acre-feet per year. In place of these waters, the United States will substitute an equal quantity of other waters from above Imperial Dam and from wells on Yuma Mesa in Arizona. For the remainder of 19 72 the United States will substitute 73, 000 acre-feet for the Wellton-Mohawk drainage water. This sum will consist of41,000 acre-feet from above Imperial Dam and 32, 000 acre-feet from wells on Yuma Mesa.
On an annual basis, the United States will thus deliver to Mexico • its Treaty amount of 1. 5 million acre-feet without including the drainage waters from Wellton-Mohawk. The substituted water is supposed to reduce the annual average salinity of water delivered to Mexico from 1 , 242 parts
Unilaterally, Mexico has requested the United States to also
dis-charge below Morelos Dam the remainder of the drainage water from the
Wellton-Mohawk Project which amounts to about 100, 000 acre-feet per year. No substitution is being made for that water. This action will further reduce the salinity.
Minute No. 241 superseded Minute No. 218 adopted in 1965. Under
Minute No. 218, the United States constructed by-pass works at a cost of about $12 million which reduced the salinity of Mexico's water from 1,375
parts per million to about 1 , 242 parts per million. Attached is a copy of
Minute No. 241.
