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<br />OOlG83 <br /> <br />8. Releases From Lakes Powell and Mead <br />-.-.-.-.---- <br /> <br />8.1 General <br /> <br />Releases are made from Lakes Powell and Mead to meet specific require- <br />ments. Although both reservoirs are operated each month to meet target <br />storage levels, like other reservoirs, releases are usually controlled <br />by the sp~cific requirements of ~ach. <br /> <br />Releases from Lake Powell are made to satisfy an objective minimum <br />release SClkd'll~. A.dditional releases are made (1) if Lake Powell <br />exceeds its maximum capacity or target storage levels, (2) if additional <br />releases are dictated by the surplus strategy, or (3) if additional <br />releases are needed to equalize the contents of Lakes Powell and Mead. <br /> <br />Releases from Lake Mead are made to sati sfy downstream demands. <br />A.dditional releases are made (1) if Lake Mead exo.!IJds its maximum <br />capacity or target storage levels, (2) if additional releases ar.'J needed <br />to meet the target storage levels of Lakes Mohave and Havasu, (3) if <br />additional releases are dictated by the surplus strategy, or (4) if <br />releases are needed for flood control regulation. <br /> <br />8.2 Releases from Lake Powell <br />- ,-- - ... _.__.- <br /> <br />Releases from Lake Powell can be categorized as following either (1) an <br />objective minimum release schedule, or (2) a schedule which is in excess <br />of this minimum. Releases are always scheduled first to follow the <br />objective minimum release schedule, and later modified if necessary. <br />Releases in excess of the minimum can be caused by either (1) Lake <br />Powell exceeding maximum capacity and spilling, (2) releases dictated by <br />the surplus strategy, if used, whereby excess releases are scheduled to <br />avoid spills, or (3) releases needed to equalize the active contents of <br />Lakes Powell and Mead by the end of the water year. The objective I~ini- <br />mum release is discussed in section 8.2.1, the surplus strate9Y is <br />discussed in section 8.4, and releases which are scheduled for equaliza- <br />tion are discussed in section 8.2.2. <br /> <br />.8.2.1 Objective Min_imum Release <br /> <br />Article 11(2) of the current Criteria for Coordinated Long-Range <br />Operati on of Colorado Ri ver Reservoi rs specifi es "the objecti ve shall <br />be to maintain a minimum release of water from Lake Powell of <br />8.23 million acre-feet." The CRSM schedules Lake Powell releases to <br />meet this Objective minimum release. In the CRSM, this annual <br />release is divided into 12 monthly releases \1hich serve as the objec- <br />tive minimum monthly releases for Lake Powell. These 12 values are <br />entered in the CRSM input control file and are used by the model in <br />the operation of Lake Powell. Lake Powell monthly releases are equal <br />to these Objective minimum releases unless the releases are increased <br />due to equalization of reservoir contents with Lake Mead, additional <br />releases scheduled by a specified surplus strategy, or the contents <br />of Lake Powell exceed maximum capacity of the reservoi r. If it is <br /> <br />33 <br />