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<br />this storage provides the bulk of the flows in average and dry years, <br />it is not practical to restrict spring storage in wet years. The <br />descending limb in wet years closely approximates the historic flows. <br /> <br />During average years, the ascending limb of the hydrograph more <br />closely approximates the historic pattern, but some increased use <br />and/or storage is reflected in the flows received at the habitat <br />area. The descending limb in average years closely approximates the <br />historic flow pattern. <br /> <br />In dry years, only the minimum release for trout is in the stream <br />until the slug release in May and June. This results in a very steep <br />ascending limb of the hydrograph. Once again, the descending limb <br />closely approximates the historic flow pattern. <br /> <br />The flows in 1987 were far from typical, even under historic <br />conditions. The very high winter flows (almost five times higher <br />than in our typical wet years) provided a strong base flow that built <br />gr~dually to a high peak. This flow pattern resulted from a high <br />level of Navajo Reservoir prior to the spring peak caused by lack of <br />demand at present for Navajo Yield. When a yearly spring release is <br />made under the reasonable and prudent alternative, this atypical <br />situation is very unlikely to recur. The descending limb in 1987 <br />reverted to its typical flow pattern. <br /> <br />2. During 7-year Test Period (with the initial depletion of 57,100 AF for <br />the Animas-La Plata Project) <br /> <br />This scenario describes the result of operating the system in accordance <br />with the reasonable and prudent alternative. The level of depletions <br />includes the section 7 baseline (reoperated as described above) with the <br />initial depletion of 57,100 AF annually associated with the construction <br />of stage A. As with the reoperated scenario, the minimum release from <br />Navajo Dam for trout will be 300 cfs and 300,000 AF will be released for <br />endangered fish in June whenever possible. The release for endangered <br />fish was able to be made in 96 percent of the years. <br /> <br />a. Magnitude of Peaks Compared to Historic <br /> <br />The level of depletions in the San Juan River Basin has increased <br />since the pre-Navajo Dam era, Navajo Dam is storing water during the <br />peak runoff, therefore, the peaks are lower than historic. During <br />wet years, for instance, the historic peaks in 1938 and 1949 were <br />11,478 cfs and 12,566 cfs respectively. Under the current level plus <br />initial Animas depletions, Navajo Dam can be operated to achieve <br />peaks of 9,203 cfs and 10,527 cfs respectively. These peaks are <br />still comparable to the 1987 peak of 9,026 cfs. <br /> <br />During average years, the historic peaks in 1936 and 1945 were <br />6,905 cfs and 7,419 cfs respectively. Under the current level plus <br />initial Animas depletions, Navajo Dam can be operated to achieve <br />peaks of 5,465 cfs and 5,582 cfs respectively. Under average <br /> <br />11 <br />