Confidential Status Memorandum on Colorado Salinity Problem

Memorandum: From J.F. Friedkin, "Status Memorandum - September 28, 1964, Colorado River Salinity Problem" (thermofax), page 2CONFIDENTIAL -2- c) Salinity of waters to Mexico will at times be between 1,500 and 1,600 p.p.m. Interior advised that its estimate was based upon annual diversions to the Wellton-Mohawk District of 450,000 acre-feet at 900 p.p.m. and return flows amounting to 200,000 acre-feet. Resulting Salinities to Mexico Using Interior's advice that the Wellton-Mohawk effluent to Mexico would have a salinity of 5,000 p.p.m. (when not by-passing), the resulting salinity to Mexico as estimated by this Section indicates that: a) A salt balance of 1.5:1 can be achieved. b) Average salinities to Mexico at the northerly boundary would range: (1) 1,360 p.p.m. in the winter, to (2) 1,420 p.p.m. in the summer. c) Maximum salinities over 1,500 p.p.m. would obtain in two or more months, depending upon the availability and distribution of the additional excess flow amounting to 25,000 acre-feet. Discussion Mexico can hardly be expected to accept such a by-pass operation, since it is no improvement over tile drains, which Mexico stated it could not accept. It is estimated that Mexico would have to by-pass approximately 40,000 acre-feet of its waters with charge to keep salinity at or below 1,500 p.p.m. This would be politically very difficult for Mexico. It is believed pertinent here to review the previous United States estimates and advice to Mexico: a) In the initial negotiations for a river-by-pass, Interior predicted and Mexico was informed that the probable salinity of Wellton-Mohawk effluent to Mexico would be 3500 to 4000 p.p.m. This estimate was on the basis of 5,000 acres additional tile in the District and by-passing a maximum of 50 days. It would result in salinities to Mexico of 1200 to 1400 p.p.m. b) In the tile drain considerations, the Denver conference predicted and Mexico was informed that the probale salinity of Wellton-Mohawk effluent would be 4000 to 5000 p.p.m. CONFIDENTIALEpson Perfection 4870 Photo, 400 dpi, 8 bit, 2,475,938 byte