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34 <br />availability, the Service used figures in the water availability study report <br />and considers this data to be the best scientific and commercial data <br />available. The Service used figures provided by action agencies and relied on <br />these numbers to reflect proposed depletions which will be consulted upon. <br />The Service recognizes that year-to-year depletions will vary significantly as <br />they are influenced by the hydrology of the water year, local weather~.patterns <br />during the summer which affect consumptive use and diversions, and flexibility <br />users have in obtaining alternate sources of water. The Service will fully <br />consider such variances during formulation of our final flow recommendations <br />for the Duchesne River. <br />The Duchesne River Basin historically produced about 768,000 acre-feet of <br />water annually based on estimates of irrigated acreage and consumptive use <br />calculations prepared by the Bureau of Reclamation using a 1912-1990 period of <br />record. As documented in Table 1, and in a letter from Assistant State <br />Engineer--Jerry Olds to George Smith, October 24, 1997, Federal projects <br />(447 KAF) and private uses (120 KAF? of Duchesne River Basin water results in <br />an average annual depletion of 567,000 acre-feet from the Duchesne River <br />Basin. Theoretically, the average annual flow remaining in the Duchesne River <br />(i.e. 768K-567K) is 201,000 acre-feet. The Central Utah Water Conservancy <br />District notes that during the 5-year period from 1989 to 1994 the average <br />flow at the Randlett gauge was only 92,327 acre feet (CH2M Hi11.1997). While <br />it is generally recognized that the Randlett gauge is inaccurate and that this <br />period reflects the driest 5-year period on record, it does demonstrate that <br />the actual hydrologic conditions can include extended periods with reduced . <br />water availability for both consumptive uses and. environmental protection. <br />Water depletions reduce the ability of the river to create and maintain the <br />primary constituent elements of critical habitats, as defined in the Final <br />Rule (Federal Register, Volume 59, No. 54, Monday, March 21, 1994). Such <br />constituent elements are necessary for survival and recovery of the endangered <br />fishes. Survival equates to the species' persistence, beyond the conditions <br />leading to its endangerment, with sufficient resilience to recover from <br />endangerment. Said another way, survival is the condition in which a.species <br />continues to exist into the future while retaining the potential for recovery. <br />This condition is characterized by a species with a sufficiently large <br />population, represented by all age classes, genetic heterogeneity, and a <br />number of sexually mature individuals producing viable offspring, that exists <br />in an environment providing all requirements for completion of the species' <br />entire life cycle, including reproduction, sustenance and shelter. Primary <br />constituent elements include, but are not limited to, water, physical habitat, <br />and the biological environment. Water includes a quantity of water of <br />sufficient quality delivered to a specific location in accordance with a <br />