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THE WHITE HOUSE WASHINGTON November 7, 1964 Dear Senator Hayden: A number of proposals have been considered to resolve the salinity problem with Mexico but none of them has as yet proved mutually satisfactory to the United States and Mexico. You will recall that you discussed with the Secretary of State and Mr. Dungan a proposal involving the construction of an extension to the existing Wellton-Mohawk conveyance channel and a commitment to Mexico that salts from the Wellton-Mohawk District delivered to Mexico for diversion into the Alamo Canal would not exceed by 1.5 times the amount of salts received by the District in its irrigation water. Any drainage containing salts in excess of this commitment were to be bypassed through the extension canal to the Gulf of California without charge to Mexico. Mexico found this proposal unacceptable essentially because it required Mexico to take drainage from the District which it did not regard as "return flow" as that term is defined in the Treaty. It would have accepted the proposal on the basis of a salt balance index of 1:1. We could not achieve a 1:1 salt balance index without the release of significant quantities of stored water. We therefore proposed to Mexico that a gravity drain system be installed in the District. We informed Mexico that we could not be entirely certain of the results, but that if we proceeded with such a system it would have to be acceptable to Mexico whatever the results. We furnished Mexico with Bureau of Reclamation predictions of the results. After careful study, Mexico concluded that the saline content of the water delivered at the boundary would exceed 1500 ppm for significant portions of the year. Since Mexico regards such water as unusable for agriculture, it also found this alternative unacceptable. I understand that you also had some doubts about this alternative because it would cost about $26 million, almost half the original cost of the construction at Wellton-Mohawk withoutEpson Perfection 4870 Photo, 400 dpi, 8 bit, 9,999,872 byte