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<br />January 7, 2004 16 <br />April through July unregulated inflow into Lake Powell in water year 2003 was 3.92 maf(4,830 <br />mcm), or 49 percent of average. Water year 2003 unregulated inflow was 6.4 maf(7,845 mcm), or <br />53 percent of average. Lake Powell reached a peak elevation of3,616.6 feet (1,102.3 meters), 83.4 <br />feet from full, on June 23, 2003. The elevation of Lake Powell on September 30,2003, was 3,603.7 <br />feet(1 ,098 meters), 96.3 feet from full. The water surface of Lake Powell had not been this low <br />since 1973, prior to the reservoir's first filling in 1980. <br /> <br />On April 24, 2002, members of the Glen Canyon Adaptive Management Work Group (AMWG) <br />recommended to the Secretary that an experimental flow test be made from Glen Canyon Dam <br />beginning in water year 2003. The recommendation addressed the decline of two key resources in <br />the Grand Canyon: sediment and population viability of endangered humpback chub. Reclamation, <br />the National Park Service, and the United States Geological Survey jointly prepared an <br />Environmental Assessment (EA) under the National Environmental Policy Act (NEP A) to document <br />the impacts of these proposed experimental flows. The Proposed Experimental Releases from Glen <br />Canyon Dam and Removal of Non-Native Fish EA (September 2002) incorporates a Biological <br />Assessment for the Fish and Wildlife Service under the Endangered Species Act (ESA). A Finding <br />of No Significant Impact on the experimental releases was signed by the three agencies on December <br />6, 2002. <br /> <br />Daily high fluctuating releases from Glen Canyon Dam, as part of the experimental flows, were <br />carried out from January through March, 2003. Releases during this three month period ranged <br />between a high of 20,000 cubic feet per second (cfs) to a low of 5,000 cfs each day. The January <br />through March high fluctuating releases were intended to benefit the endangered humpback chub by <br />reducing the spawning and recruitment of nonnative fish. These same high fluctuating releases are <br />scheduled to be repeated in January through March of 2004. <br /> <br />Retention of sediment in the Grand Canyon is also an aspect of the experimental flows. If <br />significant sediment input (over one million metric tons) to the Grand Canyon from the Paria River <br />had occurred in the summer or fall of2003, and 800,000 metric tons were retained by January 1, <br />2004, as described in the EA, a 2-day test release of 42,000 to 45,000 cfs from Glen Canyon Dam <br />would have been made in 2004, as part of the experimental flows, to understand mobilization of <br />sediment and beach and habitat creation in the Grand Canyon corridor. Additionally, the 2-day test <br />releases of 42,000 to 45,000 cfs would occur in January through March of2004 if winter sediment <br />inputs exceed 800,000 metric tons as described in the EA. <br /> <br /> <br />During water year 2004, the minimum release objective of 8.23 maf (1 0, 152 mcm) will be made <br />under the most probable and minimum probable inflow conditions. Above average inflow to Lake <br />Powell in 2004 may require that releases greater than 8.23 maf be made to equalize the storage <br />between Lakes Powell and Mead. Under the probable maximum inflow scenario, approximately <br />9.19 maf(11,300 mcm) will be released. Experimental flows in 2004 will not alter the total volume <br />of water to be released from Lake Powell during water year 2004. <br /> <br />Because ofless than full storage conditions in Lake Powell resulting from four consecutive years of <br />below normal runoff, releases for dam safety purposes are highly unlikely in 2004. Ifimplemented, <br />releases greater than powerplant capacity would be made consistent with the 1956 Colorado River <br />