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<br />, <br /> <br />30 <br /> <br />on hydrologic conditians and Reclamation's water release needs, a target <br />flow far Jensen will -be selected in the range of 1,100-1,800 cfs which <br />will remain in effect through the summer period. Fluctuations will <br />deviate na mare than 25 percent around the established flow, while <br />remaining within the 1,100-1,800 cfs range. For example, if 1,600 cfs is <br />se 1 ected as the target flaw, then flows as measured at Jensen wi 11 rema in <br />between 1,350-1,800 cfs; or if a target .of 1,300 cfs is selected, then <br />flows will remain between 1,100-1,625 cfs. These ranges are not daily <br />means but are hourly values as measured at the U.S. Geological Survey <br />gauge at Jensen, Utah. <br /> <br />A summer freshet originating from the Yampa River .or any other tributary <br />would not require a change in release from Flaming Gorge Dam ta <br />compensate for the additional flow. We assume that these were natural <br />events historically and can probably be tolerated by the native species. <br />Releases from Flaming Gorge beginning July 1 and continuing until <br />Navember 1 should be of the warmest water available, appraaching 15.C <br />(highest lake levels). By releasing the warmest water available during <br />this period, water temperatures in the upper Green River should not <br />differ more than 5 .C from the temperature in the Yampa River at Echo <br />Park and shauld average near 22-25 .C in Gray Canyon from July 1 to <br />August 15. <br /> <br />Autumn <br /> <br />Autumn flows are a continuation of the late summer flows described above. <br />Hawever, if the year was classified as wet during the April coordination <br />meeting and a need to release excess water still exists, the target flow <br />may be increased to within the range of 1,100-2,400 cfs. If water <br />conditions dictate, the new' target may be selected on or after <br />September 15. The 25-percent fluctuation around the target flow remains <br />in effect. Green River flows (measured at Jensen) at or below 2,400 cfs <br />should be sustained until November 1 of each year. During average and <br />dry years, the target flows selected for summer will remain in effect. <br />Flows after November 1 are addressed in the winter period. <br /> <br />Winter <br /> <br />The goal for winter releases is to provide low, stable flows near <br />historic levels. Winter flows should be stabilized once ice cover forms <br />and remain so through normal spring breakup. The exception to this is <br />when it becomes evident that higher winter releases are necessary to <br />ensure meeting spring thraugh autumn flows. Under ice conditions, <br />fluctuating flows that promote ice breakup, jams, and shoreline scoring <br />in the mainstream Green River are undesirable for adult fish. Under <br />conditions when ice does nat form or when specific research flows are not <br />requested, flows may be operated within constraints of Reclamation's <br />agreement with the State of Utah and the need to release water during wet <br />years. If possible, fluctuations during this period should be moderated. <br />The winter period also should be used to manage Flaming Garge storage ta <br />ensure that flows needed for the following spring peak and summer low, <br />stable period will be provided. <br />