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<br />-2- <br /> <br />Summer Low Flow Test Report - April 2002 <br /> <br />I <br />I <br />I <br />,. <br />. <br />I <br />I <br />. <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Proposed Navajo Dam operational changes represent a <br />degree of departure from past practices which, after the <br />Navajo Unit's completion in 1963, stressed maintaining <br />stable flows and maximizing reservoir storage, For <br />example, operational changes could involve dam releases of <br />5,000 cfs for peak spring flows followed by lower releases <br />ranging from 250 to. more than 500 cfs during the remainder <br />of the year, <br /> <br />Purpose <br /> <br />This Test, along with the results of the 1996-97 Winter Low <br />Flow Test (Reclamation, 1998), provides data to be <br />considered when preparing an EIS. Public and agency <br />concerns arose when it became widely known that low <br />flows of 250 cfs could occur in the summer as well as <br />during the winter-in fact, at any time other than the spring <br />peak flow period in May and June. <br /> <br />Generally, as described in the Flow Recommendations, <br />releases from Navajo Dam to the San Juan River comprise <br />a spring peak maximum release of 5,000 cfs and lower <br />releases targeted to maintain year-round flows of 500- <br />1,000 cfs in the critical habitat (downstream of Fannington, <br />New Mexico, to Lake Powell), Releases from the dam <br />could be decreased to as low as 250 cfs when tributary <br />inflows cause the critical habitat reach of the river to <br />approach the upper end of the 500 to 1,000 cfs flow2, Also, <br />these reduced releases are necessary to store water in <br />Navajo Reservoir to enable spring peak releases to be made <br />the following year and to store water for development, <br /> <br />2 The EIS will discuss possible flexibility that may allow higher summer flows. <br />