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<br />002637 <br /> <br />REVISED BASE-fLOW RECOMMENDATIONS FOR THE Y AMP A RIVER <br />U.S. Fish and Wildlife Service, Mountain-Prairie Region (6), Denver, Colorado <br /> <br />The following information is provided as the basis of flow recommendations for the Yampa River <br />during the base-flow period (July-February). It formally supplements and amends previous flow <br />recommendations of the U.S. fish and Wildlife Service (Service) for the Yampa River (Modde and <br />Smith 1995). The amended recommendations are intended to serve as the basis for instream flow <br />augmentation from July through February as outlined inA Management Planfor Endangered Fishes <br />in the Yampa River Basin (Roehm 2003). <br /> <br />Background <br /> <br />The Service first attempted to develop flow recommendations for the Yampa River in 1989 (Tyus <br />and Karp 1989), in which the authors identified the life history and general habitat needs of the <br />Colorado squaw fish (now commonly known as the Colorado pikeminnow), humpback chub, <br />razorback sucker and the bony tail. The report made some general observations about flows that <br />appeared to be beneficial to the endangered fish based on historical hydrologic conditions. Although <br />the report did not provide any discrete flow recommendations for the Yampa River, it identified a <br />need to maintain both inter- and intra-annual variability typical of historical hydrographs. flow <br />recommendations were to be developed separately in a stand-alone document. <br /> <br />After completion and acceptance of this report, the Service released what was known as Phase II <br />flow recommendations for the Yampa River on November 9, 1989. The Phase II report relied upon <br />the biological information from Tyus and Karp (1989) and took into consideration water-project <br />depletions backcast over historical monthly hydrologic records for the Yampa River to develop <br />monthly flow recommendations at Deerlodge Park. The Phase II flow recommendations proved <br />to be too general, and because they were based on flows at Deerlodge Park, they did not correlate <br />with flows at the Maybell gage, which historically has been used for stream-flow accounting. <br /> <br />Modde and Smith (1995) developed flow recommendations for the Yampa river that updated <br />interim recommendations for the Yampa River, which were promulgated by the Service in 1990 <br />based on a review of biological data on endangered fishes developed by Tyus and Karp (1990). The <br />approach used by Modde and Smith (1995) was selected following the failure of an Instream <br />flow Incremental Methodology (IFIM) Physical Habitat Simulation (PHABSIM) to demonstrate <br />predicative cause-and-effect relationships between instream flows and distribution of endangered <br />fishes in the Green River Basin (Rose and Hann 1989). flows recommended in the Modde and <br />Smith 1995 report relied heavily on biological information presented by Tyus and Karp (1989), but <br />also included information generated by endangered fish monitoring activities carried out by the <br />Upper Colorado River Endangered fish Recovery Program; an instream flow report by Dr. Jack <br />Stanford (Stanford 1993); a comparison by The Nature Conservancy of estimated historic and <br />undepleted Yampa River flows at Maybell (O'Brien 1987); and generally accepted, published <br />ecological principles. <br /> <br />~ <br />, <br /> <br />Appendix D - Revised base-flow recommendations for the Yampa River <br /> <br />0-1 <br />