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COLORADO RIVER COMPACT WATER DEVELOPMENT PROJECTION <br />November 2, 1995 FINAL REPORT <br />Page 11 <br />IV. COLORADO'S COMPACT APPORTIONMENT <br />During the 1922 Compact negotiations, it was believed that the long-term average <br />water supply at Lee Ferry, Arizona was greater than 15.0 MAF per year and that there would <br />be at least 7.5 MAF annually available for use in the Upper Basin. Furthermore, it was <br />believed that there was at least enough water originating in the Lower Basin to satisfy the <br />Mexican Treaty obligation of 1.5 MAF annually and satisfy an additional 1.0 MAF of annual <br />consumptive use in the Lower Basin. Under the above assumptions, Colorado would have at <br />least 3,855,375 acre feet of annual consumptive use available to it. However, it has become <br />apparent that long term water supply conditions were overestimated and that the average <br />annual water supply at Lee Ferry is only approximately 15 MAF, which is insufficient to meet <br />the Mexican Treaty obligation and provide 7.5 MAF of consumptive use to both the Lower <br />and Upper Basins. <br />In addition, the 1922 compact made the 7.5 MAF apportionments to each of the Upper <br />and Lower Basins from the waters of the "Colorado River System." The "Colorado River <br />System" is defined in the 1922 compact as "that portion of the Colorado River and its <br />tributaries within the United States of America.." However, the 1964 decree in Arizona v. <br />California only allocated 7.5 MAF among the Lower Basin states from the Colorado River <br />mainstem, and refused to apportion the use of Lower Basin tributaries. <br />Consequently, the Long Range Operating Criteria provide that at minimum 8.23 MAF <br />be released annually from Lake Powell (7.5 MAF to the Lower Basin plus .75 MAF for one- <br />half the Mexican Treaty obligation less .02 MAF of tributary inflow between Glen Canyon <br />and Lee Ferry). Although the Secretary of the Interior has disclaimed any intent to interpret <br />the "Law of the Colorado River" in promulgating the criteria, the criteria effectively require <br />the Upper Basin to deliver annually one-half of the Mexican Treaty obligation at Lee Ferry. <br />It should be emphasized that the Upper Basin States have never agreed to or concurred with <br />the concept of supplying one-half of the Mexican Treaty obligation each and every year. <br />These varying assumptions of water supply and interpretation of the Mexican Treaty <br />obligation result in different interpretations of the water supply available to the Upper Basin <br />and Colorado as shown in Table 2 below. <br />