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<br />conditions flows are moderately less than historic spring peaks and <br />are likewise significantly less than the 1987 spring peak. <br /> <br />In dry years, the spring peak can be enhanced significantly with <br />storage releases from Navajo Dam. Historic peaks in 1946 and 1951 <br />were 3,427 cfs and 3,169 cfs respectively. Under the current level <br />plus Animas M&I depletions, Navajo Dam can be operated to achieve <br />peaks of 4,457 cfs and 4,122 cfs respectively. These peaks are <br />comparable to historic peaks in an average year, but are higher than <br />historical peaks for dry years. <br /> <br />b. Shape of Hydrograph (ascending/descending limbs) <br /> <br />Examining the hydrograph developed for current level and current <br />level plus Animas, there is no change in the shape of the hydrograph. <br />The only change evident is a reduction in volume equal to the initial <br />Animas-la Plata Project depletions each month. <br /> <br />4. Under Full San Juan River Basin Depletion <br /> <br />Although there is no commitment in this Biological Opinion and reasonable <br />and prudent alternative for future Section 7 consultations, it is useful <br />in this analysis to look at flow pattern under full depletion. Full <br />depletion, for this analysis, is defined as full development of compact <br />allotments by Colorado, Utah, and New Mexico (not full Animas-la Plata). <br />Under this scenario, only 290 cfs can be provided as a minimum release <br />from Navajo Dam for trout. As with the other scenarios, 300,000 AF will <br />be released for the endangered fish in June whenever possible. The <br />endangered fish release can be made only 33 percent of the time under <br />these assumptions. <br /> <br />This flow scenario is somewhat misleading. Until the research required <br />under the reasonable and prudent alternative is completed and the <br />biologists can quantify the amount and timing of the flows needed to <br />establish a self-sustaining endangered fish population, a realistic flow <br />scenario cannot be developed. For example, reducing the flow releases in <br />dry years to adult maintenance levels would increase the number of years <br />that spring peaks could be augmented. <br /> <br />12 <br />