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<br />GREEN RIVER STUDY PLAN <br /> <br />4 <br /> <br />February 2,2007 <br /> <br />4. restore and maintain the channel complexity and dynamics needed for formation and <br />maintenance of high-quality spawning, nursery, and adult habitats; <br /> <br />5. provide base flows that promote favorable conditions in low-velocity habitats during <br />summer, autumn, and winter; and <br /> <br />6. minimize differences in water temperature between the Green River and Yampa River in <br />Echo Park to prevent cold shock and possible mortality to larval Colorado pikeminnow <br />transported from the Yampa River into the Green during summer. " <br /> <br />The recommendations included target flows and temperatures specific to reaches of the <br />Green River downstream of Flaming Gorge Dam because habitats of the endangered fishes, <br />hydrology, and geomorphology vary longitudinally by these reaches. Flow and temperature <br />recommendations and their anticipated effects on the endangered fishes and their habitats were <br />presented for each of three reaches (Figure 2): <br /> <br />· Reach 1 - Flaming Gorge Dam to Yampa River confluence; <br /> <br />· Reach 2 - Yampa River confluence to White River confluence; and <br /> <br />· Reach 3 - White River confluence to Colorado River confluence. <br /> <br />The flow and temperature recommendations identified uncertainties associated with their <br />implementation and recognized the importance of managing for unanticipated effects. Following <br />are uncertainties summarized from Muth et al. (2000). <br /> <br />1. The paradigm in river management suggests that the ecological integrity of river <br />ecosystems is linked to their natural dynamic character and that restoring a more natural <br />flow regime to an impaireq system is the cornerstone of rehabilitation. This paradigm <br />and the response by the endangered fishes of the Green River system are largely untested. <br /> <br />2. The recommendations assumed that future changes in flow, temperature, and sediment <br />regimes of Green River tributaries will be consistent with existing or known pending <br />biological opinions. Unanticipated changes in current tributary conditions could result <br />from modifications in the operation of existing water projects or from the development of <br />new water projects. <br /> <br />3. The physical response of the system to flows is fairly well understood, and the flow <br />recommendations are of the magnitude, duration, and frequency needed to restore much <br />of the dynamic character of the Green River downstream of Flaming Gorge Dam. It was <br />assumed that restoring physical processes and improving habitat conditions will elicit <br />positive responses from endangered fish populations, but responses of the long-lived <br />endangered fishes to the recommendations will take time and need to be monitored. <br />