Letter: From Thomas C. Mann, to Stewart Udall, November 2, 1964 (carbon copy), page 1DEPARTMENT OF STATE WASHINGTON LIMITED OFFICIAL USE NOV 2 1964 Dear Mr. Secretary: Since my letter of August 5 there have been a number of developments in our attempt to resolve the Colorado River salinity problem with Mexico. Most significantly, the Government of Mexico concluded that it could not accept installation of a tile drainage system at Wellton-Mohawk as the "permanent and effective solution" contemplated in the Presidential Communiques. Based on estimates by Interior Department engineers that the tile drain effluent may have a salinity of 4-5,000 ppm, Mexican engineers estimate that the salinity of the water reaching Mexico would a...