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1998 DETERMINATIONS <br />The AOP provides guidance regarding reservoir storage and release conditions during the <br />upcoming year, based upon Congressionally mandated storage, release, and delivery criteria and <br />determinations. After meeting these requirements, specific reservoir releases may be modified <br />within these requirements as forecast inflows change in response to climatic variability and to <br />provide additional benefits coincident to the projects' multiple purposes. <br />Upper Basin Reservoirs <br />The Operating Criteria provide that the annual plan of operation shall include a determination <br />of the quantity of water considered necessary to be in Upper Basin storage at the end of the <br />water year. Taking into consideration all relevant factors required by the Operating Criteria, it <br />has been determined that the active storage in Upper Basin reservoirs forecast for September 30, <br />1998 exceeds the storage required under Section 602(a) of the Colorado River Basin Project Act <br />under any reasonable range of assumptions which might be applied. Therefore, "602(a) Storage" <br />is not the criterion controlling the release of water from Glen Canyon Dam during water year <br />1998. <br />Section 602(a)(3) of the Colorado River Basin Project Act provides for the storage of Colorado <br />River water in Upper Basin reservoirs that the Secretary of the Interior finds necessary to assure <br />deliveries to comply with Articles III(c) and III(d) of the 1922 Colorado River Compact, without <br />impairment to the annual consumptive use in the Upper Basin. The Secretary is required to <br />make this determination after consultation with the Upper Colorado River Commission and <br />representatives from the three Lower Division States, and after taking into consideration all <br />relevant factors including, historic stream flows, the most critical period of record, the <br />probabilities of water supply, and estimated future depletions. Water not required to be so stored <br />will be released from Lake Powell: <br />to the extent it can be reasonably applied in the States of the Lower Division to the uses <br />specified in Article III(e) of the 1922 Colorado River Compact, but these releases will <br />not be made when the active storage in Lake Powell is less than the active storage in <br />Lake Mead, <br />to maintain, as nearly as practicable, active storage in Lake Mead equal to the active <br />storage in Lake Powell, and <br />to avoid anticipated spills from Lake Powell. <br />Spill avoidance and /or storage equalization criterion in accordance with Article II(3) of the <br />Operating Criteria will control the releases from Glen Canyon Dam during water year 1998 <br />unless the minimum objective release criterion in Article II(2) is controlling. Under the most <br />probable inflow scenario Glen Canyon Dam will release 13,260 MCM (10.750 MAY). <br />September 3, 1997 16 <br />