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<br />. <br /> <br />. <br /> <br />an allotment to Mexico of 1,500,000 acre-feet annually. . of Ihe \Valers of Ille Colorado <br />Ril'er, frolll allY alld all sources . It was not until 1961. with the increase in river <br />water salinity, that the quality of the water became a chief concern to Mexico. In November <br />of that year Mexico formally protested to the United States that Ihe delivery of <br />waler Ihal is harm!i" for Ille purposes srared ill Ihe rreary collsrilllles a !'iolalion of Ihe <br />treaty <br />In response to efforts by Mexico in 1963 anu 1964. the United States began to <br />modify its riwr operations. In March 1965, a 5-year agreement was reached by the two <br />Governments, referred to as Mill II Ie No. 218 [6J of the International Boundary and Water <br />Commission. The Minute. under which each country reserved its legal rights, became <br />effective on November 16, 1965. and provided for practical measures to further reduce <br />the salinity of waters reaching Mexico. These measures consisted of the construction and <br />operation of the 11-mile-Iong MODE from the end of the We11ton-Mohawk Main <br />Conveyance Channel (WMMCC) to Morelos Dam to enable the United States to discharge <br />\Vellton-Mohawk drainage water to the Colorado River either above or below Morelos Dam <br />(Mexico's diversion structure on the river). and the installation and operation of additional <br />drainage wells in the Wellton-Mohawk Division to facilitate selective pumping. When <br />scheduled deliveries to Mexico were the Treaty minimum. the Unite1 States discharged <br />all Wellton-Mohawk drainage below Morelos Dam, and the difference was mac!e up by <br />other water largely from above Imperial Dam. This amounted to about 50.000 acre-feet <br />per year. By the end of 1971 (Minule No. 218 had been extended 2 years). these operations. <br />coupled with a gradual improvement in the quality of Wellton-Mohawk drainage water, <br />had reduced the average annual salinity of water available for delivery to Mexico at the <br />Northerly International Boundary to about 1,245 p/m, with monthly averages varying from <br />1.105 to nearly 1,500 p/m. Mexico concluded, however, that it would not use water with <br />a salinity greater than about 1,240 p/m in the Mexicali Valley and asked the United States, <br />unuer tnms of Millule No. 218, to bypass an additional 40,000 to 75.000 acre-feet of <br />Welllon-Mohawk drainage nows annually. The effect was to further reduce the average <br />salinily of water diverted by Mexico at Morelos Dam to about 1.160 plm in 1971. <br /> <br />. <br /> <br />3 <br />