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<br /> <br />Operation of Glen Canyon Dam <br /> <br />Pursuant to the 1956 CRBP A, Glen Canyon Dam, Hoover Dam and other major Reclamation <br />reservoirs are operated pursuant to the "Criteria for Coordinated Long Range Operation of Colorado <br />River Reservoirs." These criteria were last reviewed and amended on March 21, 2005.140 <br /> <br />For the most part, the criteria simply restates portions of Section 602 (a) of the 1968 CRBP A <br />and relevant portions of the decree in Arizona v. California. 141 The criteria goes beyond Section 602 <br />(a) for one critical decision. The criteria defmes a minimum objective release of 8.23 maf per year. <br />A minimum objective release is made if either the active storage in Upper Basin reservoirs is less <br />than the 602 (a) trigger or if Lake Powell active storage is less than Lake Mead active storage. <br /> <br />The 8.23 maf per year release can be derived as follows: <br /> <br />7.5 maf - which happens to be 75 maf divided by 10 (Article III (d) of the 1922 Compact). <br /> <br />plus .75 maf - which happens to be the Mexican Treaty obligation of 1.5 mat/year divided by 2. <br /> <br />less .02 maf - which is the approximate flow of the Para River - an Upper Basin tributary that <br />enters the Colorado above Lee Ferry, but below Glen Canyon Dam. <br />equals 8.23 maf <br /> <br />The criteria includes an additional comment: "Releases from Lake Powell pursuant to these <br />criteria shall not prejudice the position of either the upper or lower basin interests with respect to <br />required deliveries at Lee Ferry pursuant to the Colorado River Compact." <br /> <br />Figure V -6 is a graph showing storage in Lake Powell from late 1963 when the gates closed <br />through today. Until about 1980 when Lake Powell first filled, operations were controlled by the <br />filling criteria. Since 1981, there have been two periods when the reservoir was full, 1982-1987 and <br />1995-2000 and two periods when reservoir levels were low, 1988-1994 and 2001 to the present. <br /> <br />Figure V -7 is a bar graph showing releases from Glen Canyon Dam from 1980-2006. During <br />the two wet periods, releases were well in excess of 8.23 maf/year. But during the dry periods, <br />releases were 8.23 mat/year. <br /> <br />140 Copies of the criteria can be viewed or obtained from the Bureau of Reclamation website, www.usbr.gov.us. <br /> <br />141376 U.S. 340 (1964). <br /> <br />Page -59- <br />