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. ~ 7 Figure 2, taken from Tyus and Karp (July 1991), shows the conceptual relationships between a natural hydrograph and the timing .of life history requirements for the Colorado squawfish, humpback chub, and razorback sucker. It is this natural hydrograph with a large spring peak; a gradual descending limb inta early summer; and low, stable flows through the summer, fall, and winter that the Service believes creates the best habitat conditions for rare and endangered fish in the Green River Basin. This flaw pattern maintains long-term stability and geomorphology of the channel, prepares spawning areas, and forms nursery habitats. DEVELOPMENT AND EXTENT OF PERTINENT SCIENTIFIC DATA BASE The Act of 1973 (P.L. 93-205) charged all Federal Agencies to consider the needs of species listed as threatened and endangered. The Act also mandated all Federal Agencies to consult with the Service to ensure that their actions were not likely to jeopardize listed species. Early cansu1tations revealed the need far scientific information on the endangered species. In 1979, the collection of life history data to expand the scant data base that existed for the rare and endangered fish of the Upper Colorado River Basin began with formatian of the Ca10rada River Fisheries Project. In 1982 Reclamation and the Service continued studies on endangered fish under the Co1arado River Fishery Monitoring Pragram. These studies were to examine the effects of flows from Flaming Gorge Dam primarily an Calorado squawfish. In 1985 the Service and Reclamation agreed to an interagency Flaming Gorge Studies program that began in 1986 and ended in 1990. That program evaluated habitat requirements and streamflow needs of the rare fish and provided flow recommendations in a final report dated July 1991 (Tyus and Karp 1991). Just prior to implementing the Recovery Program in 1988, a mu1tiagency Flaming Gorge Section 7 Consultation Team was formed to evaluate biological information and ongaing studies prior to issuance of the biological opinion. The final products formulated under the direction of this team were the consolidated hydrology and bio1agy reports. The Final Consa1idated Hvdro10oy Reoort (Smith and Green 1991) provided hydrologic informatian on the past and current operation of Flaming Gorge Dam and discussed models which could be used to predict changes in sediment transport, temperature, and channel marpha10gy resulting from recommended operational changes included in this opinion. The final consolidated biological report titled Habitat Use and Streamflow Needs of Rare and Endanoered Fishes in the Green River. Utah (Tyus and Karp 1991) merged the results of numerous studies dane by a variety of government and private researchers. Together, these consolidated reports form the basis for the Service's recommended refinement of the existing. operation of Flaming Gorge Dam to improve downstream conditions for rare and endangered fish in the Green River.