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UNITED STATES DEPARTMENT OF THE INTERIOR OFFICE OF THE SECRETARY WASHINGTON 25, D. C. July 14, 1962 Memorandum To: The Secretary From: Science Adviser Subject: Colorado River Salinity Problem So far as I can see at present, we are caught here on a three-horned dilemma: 1. The insistence of the Mexican Government that under International Law and the 1944 Treaty, the water delivered to Mexico for irrigation use should not contain a greater total tonnage of salt than that initially carried by the River itself. The water being pumped from the Wellton-Mhawk District contains four times as much salt as the irrigation water received by the District. 2. The expected Supreme Court decision in Arizona vs. California, et al, in which the words, "consumptive use," will probably be defined, in the words of the Special Master's Report, as, "... diversion from the stream less such return flow thereto as is available for consumptive use in the United States or in satisfaction of the Mexican treaty obligation." Also involved is the legislation authorizing the Wellton-Mohawk project which limits the annual beneficial consumptive use for the project to 300,000 acre-feet. 3. The fact that River flows to Mexico during the winter months, exclusive of the return flows from the Wellton-Mohawk District, cannot be reduced below an average of 1,040 cfs, whereas Mexico usually schedules during these months no more than the minimum of 900 cfs provided under the Treaty. Consequently, no return flows from the Wellton-Mohawk District during the five winter months are creditable under the Treaty. Mexico's requirement, (1) above, for "salt balance" could be met by constructing a tile drain system to carry off the return flows in the Wellton-Mohawk District. But this would waste Wellton-MohawkEpson Perfection 4870 Photo, 400 dpi, 24 bit, 1,662,254 byte