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<br />000330, <br /> <br />Appendix <br />Law of the Colorado River <br /> <br />. Mexican Water Treaty of 1944 - The Mexican Water Treaty deals with the allocation <br />and management of three international rivers: the Colorado River, the Rio Grande, <br />and the Tijuana River. Under terms of the Part III of the Treaty, Mexico is normally <br />entitled to a guaranteed annual quantity of 1,500,000 acre feet of water delivered at <br />two points along the Mexican-US border. However, under extraordinary drought <br />conditions, Mexico would share any shortages with the water users in the United <br />States, and when there is water in excess of United States needs, Mexico would <br />receive a surplus delivery of up to 200,000 acre-feet. One of the terms of the Treaty <br />is that the Mexican water delivery can be derived from any water, regardless of its <br />origin. The intention ofthis provision was to recognize that return flows from <br />agricultural uses within the United States would be a significant component of the <br />water supply delivered to Mexico. The Treaty deals only with the quantity of water <br />deliveries and makes no provisions related to the quality of the water supply. <br /> <br />· Minute 242 - Minute 242 is dated August 30, 1973 and is titled "Permanent and <br />Definitive Solution to the International Problem of Salinity in the Colorado River." <br />The Minute, which is a diplomatic agreement between the United States and Mexico, <br />was intended to resolve issues raised by Mexico related to the high levels of salinity <br />in the water being delivered under the Treaty. The salinity issue came to a head after <br />the Wellton-Mohawk Irrigation District began discharging drainage return flows into <br />the Colorado River above the Mexican diversion points. The return flows were <br />especially high in salinity and Mexico protested that the water was unusable for <br />irrigation purposes. The Minute was the result of a multi-year process of study and <br />negotiations. As a result ofthe Minute, the United States agreed to deliver water at <br />the northern Mexican delivery point that would be within an average annual salinity <br />level of 115 ppm. ::1::30 ppm compared to the average annual salinity level of the water <br />at Imperial Dam. This provision has come to be referred to as meeting a salinity <br />"differentia1." The United States also agreed to bypass the return flows of the <br />Wellton-Mohawk District and deliver them to the Cienega de Santa Clara near the <br />Gulf of California. The Minute envisioned that a desalting plant would be <br />constructed to treat the Wellton-Mohawk drainage water to a point where it could <br />again be discharged to the Colorado River without violating the salinity differential. <br />Once the plant became operational, the brine stream, which is a highly concentrated <br />byproduct of the desalinization process, would be bypassed to the Cienega. <br /> <br />· Colorado River Basin Salinity Control Act of 1974- Title 1 ofthe Salinity Control <br />Act deals with features downstream of Imperial Dam and is the federal law that <br />authorized the measures necessary to implement Minute 242. <br />The Act authorized the construction and operation of the Yuma Desalting Plant <br />which was intended to reclaim a portion of the Wellton-Mohawk drainage water. All <br />costs associated with the Plant were non-reimbursable to the federal government. <br /> <br />Recommendations of the YDP/Cienega Workgroup <br /> <br />23 <br />