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<br />.-...........-- <br /> <br />, <br /> <br />2.0 FLOW RECOMMENDATIONS OF THE BIOLOGICAL OPINION <br /> <br />Changes in the Green River hydrograph resulting from implementation of flow <br />recommendations set forth in the Biological Opinion are the foundation of the 5- <br />Year Flaming Gorge Research Program presented in this document. In general, <br />after flow recommendations have been implemented, flows will more closely <br />resemble the natural historic hydrograph of the Green River than those previously <br />provided. Flow recol1ll\endations were made on a seasonal basis for spring, summer, <br />fall, and winter periods. Flow recommendations for each season are summarized <br />in the following section; refer to the 1992 Biological Opinion on operation of <br />FGD for details on flow recommendations and exceptions. Flows recommended in the <br />Biological Opinion are those measured at tbe U.S. Geological Survey gauge at <br />Jensen, Utah <br /> <br />Spri n9- Timi ng and duration of increased water releases from FGD will <br />closely correspond to spring flows in the Yampa River. Starting in April, <br />water releases will begin increasing until a peak flow of approximately <br />4,000-4,700 cfs is attained. Timing of this peak will be planned to <br />coincide with peak spring runoff in the Yampa River. Releases of <br />4,000-4,700 cfs will be provided annually for 1-4 weeks between May 15 and <br />June 1. Duration of peak releases will depend on the water year, with a <br />longer release period occurring during high water years. The post-peak <br />decline in releases will consist of at least 2,000 cfs for one additional <br />week, stepping down at a rate of not more than 400 cfsjday. The <br />descending arm of the hydrograph will be synchronized with the conclusion <br />of spring-runoff conditions in the Yampa River. During average water <br />years, the entire spring peak will occur for a period of 6-8 weeks. <br /> <br />Sunner-The rationale for sunrner flow recommendations was to maximize <br />summer nursery habitats for young-of-year (yay) Colorado squawfish. Water <br />releases from FGD will continue to decrease follOWing the spring period <br />until a flow of between 1,110-1,800 cfs is attained (actual flow within <br />the recommended cfs range will be based on Reclamation needs). <br />Fluctuations will deviate no more than 25% (based on hourly values) below <br />the established maximum flow. The date for achieving the target flow will <br />be based on the Yampa River hydrograph. During average or high water <br />years, the target flow probably will occur on or near July 10 or July 20, <br />respectively. During low water years, the target flow probably will occur <br />on or near June 20. <br /> <br />Fall-Fall flows will be a continuation of summer flows described above. <br />During high water years, however, because most yay endangered fishes are <br />past the larval period of development by fall, the upper limit of the <br />target-flow range could be increased to 2,400 cfs. If water conditions <br />dictate, a new target flow could be selected on or after September IS. <br />The standard of fluctuations below the maximum flow not exceeding 25% will <br />remain in effect. The target flow will be maintained until November 1 of <br />each year. Flows after this date are addressed in reconrnendations for the <br />winter period. <br /> <br />Flaming Gorge Studies <br /> <br />2 <br />