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<br />(\~)Cl') <br />lJ L. ';' . ~ <br /> <br />uses-most of its Colorado River water to support irrigated agriculture in the <br />Mexicali Valley, this silence seems odd. The history of the treaty suggests that the <br />U.S. and Mexico drew different inferences about quality from the phrase "any and <br />all sources," <br /> <br />) <br /> <br />Before the completion of Hoover Dam in 1935, destructive spring floods swept <br />through the Colorado Basin almost every year, followed by dangerously low flows <br />in the summer. When the river was in its natural state, Mexico could capture and <br />use only about 750,000 acre-feet of water per year. Hoover Dam made possible the <br />storage of floodwaters and year-round flow: regulation, and Mexico stood to receive <br />much more usable water-but the legislation authorizing the dam's construction <br />barred foreign governments from receiving any benefit from it! The 1944 treaty <br />contained an apparent compromise: the U.S. would deliver approximately twice as. <br />much water to Mexico as it would have been able to use had the Colorado not been <br />regu1ated- 1.5 million acre-feet-but Mexico would have no say in the source of that <br />water within the Basin, nor in its quality.2 <br /> <br />Until1961, no problems arose from the salinity of water deliveries. In that year, the <br />Wellton-Mohawk Irrigation and Drainage District in Arizona, near the Mexican <br />border, began to operate a pumped drainage system. To lower the high water table <br />beneath the project, it began to pump highly saline water into its drains-water that <br />was laden with salts that had accumulated in the soils beneath the project from <br />decades of irrigation without drainage. These drainage waters, or "return flows" <br />carried about 6,000 parts per million(ppm) of dissolved salts, and entered the river <br />just above More10s'Dam, the main'Mexican diversion point. <br /> <br />...,) <br /> <br />In the same year, the U.S. sharply reduced upstream releases-which would have <br />diluted the brackish drainage waters from Wellton-Mohawk-in order to begin filling <br />Lake Powell, behind the newly completed Glen Canyon Dam. These two events <br />caused the average annual salinity of water delivered to Mexico at More10s Dam to <br />jump dramatically, from about 800 ppm in 1960 to 1,340 ppm in 1961, to more than <br />1,500 ppm in 1962. Salinity levels in some months exceeded 2,500 ppm. In <br />November 1961, the government of Mexico filed a formal diplomatic protest, <br />charging the U.S. with violating international law. The International Boundary and <br />Water Commission (IBWC), the joint U.S.-Mexican agency charged with <br />administering the 1944 treaty, began negotiations on a practical solution. <br /> <br />For the next ten years, Mexican and U.S. scientists, diplomats, and Federal and state <br />officials debated the intent of the 1944 treaty, technical issues, and equities under <br />international law without reaching a permanent solution,3 The Committee of <br />Fourteen-composed of two representatives from each of the seven Basin states- had <br />been created in 1938 to consider basin-wide problems, including the prospective <br />treaty. At the State Department's request, the Committee was revived in the early <br />1960s to advise the U.S. Section of the IBWC on the salinity issue. <br /> <br />In 1965, the U,S., under Minute No. 218 of the IBWC, agreed to several temporary <br />measures to reduce salinity: extending the Wellton-Mohawk Drain to permit drainage <br /> <br />browneU.rpt <br /> <br />2 <br /> <br />October 1991 <br />