Memorandum of Conversation on Colorado River Salinity

Memorandum of Converation: From J.F. Friedkin, to the two Commissioners and the two Secretaries, "Colorado River Salinity," July 3, 1964, page 3CONFIDENTIAL -3- (3) U.S. Alternative (a) - A river bypass would be acceptable only on a temporary basis, if there is not time to build a separate bypass channel, because of problems in stopping of irrigation diversions for 50 days. Also, the make up over 100 days may not be acceptable. Further, and most important, this would not permit Mexico to waste additional highly saline waters charged to it without also losing its good waters. (4) U.S. Alternative (d) - Tile drainage would be last in Mexico's preference according to the Mexican Commissioner, because it would not permit bypassing of highly saline waters with Mexico accepting the charge. 3) Extension and Lining of Bypass Channel The Mexican Commissioner indicated that several Mexican authorities were of the opinion that any bypass channel should be extended and lined well below Morelos Dam--and below the Arizona boundary to avoid infiltration of highly saline waters from the river channel to contaminate the ground water basin in the Mexicali Valley from which waters are pumped for irrigation. I furnished him a copy of the records of gains and losses below Morelos Dam which indicate only small losses, if any, after Mexican diversions from this section of the river are taken into account. The Mexican Commissioner concurred that extension and lining may not be necessary. We agreed to undertake joint investigation and study as soon as indicated by the negotiations. 4) Support for 1.5:1 Salt Balance Index The Mexican Commissioner indicated that his greatest concern is the basis for justification of an index of 1.5:1 to his government. He explained that while he understood the difficulty we described in reaching in the United States an index as low in our opinion as 1.5, it seemed unduly high to him and that he would need supporting data. I stated that supporting reason is a practical one--it required all feasible operations in the United States in order to assure Mexico so low an index and at the same time permit full utilization by the United States of its waters. The Commissioner for Mexico expressed the need for scientific data to support the index of 1.5:1. He suggested that a determination be made from field data of the total discharge of water and total tons of salt that would have to be discharged from the District, if the returns were normal return flows. He suggested determination of the salt content of waters in the root zone as a basis. On this point the Mexican Commissioner agreed that if gravity drains were installed, the returns would be as nearly normal as practical. He also agreed that the waters collected by gravity drains may include some CONFIDENTIALEpson Perfection 4870 Photo, 400 dpi, 8 bit, 2,303,014 byte