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STRATEGIES FOR RESTORING AND PROTECTING INSTREAM FLOWS FOR ENDANGERED FISH IN THE UPPER COLORADO RIVER BASIN John Hamill, Director Upper Colorado River Recovery Program U.S. Fish and Wildlife Service (FWS) Box 25486, DFC Denver, CO 80225 (303) 236-2985 ABSTRACT Four native fish that inhabit the Colorado River have been federally listed as endangered: the Colorado squawfuh, the humpback chub, the bonytail chub, and the razorback sucker. The Recovery Implementation Program for Endangered Fish Species in the Upper Colorado River Basin (Recovery Program) is a consortium of federal and state agencies, environmental organizations, and private water-development interests whose mission is to recover the endangered fish in the Upper Colorado River Basin while allowing for new water development to continue. A principal objective of the Recovery Program involves acquiring and/or restoring adequate instream flows to support self-sustaining populations of the endangered fish. Priority areas for acquisition of water rights for the endangered fish in the upper basin include the Yampa River, White River, and a 15- mile reach of the Colorado River immediately upstream from the confluence of the Gunnison River. The instream flow requirements of the endangered fish have been identified for several rivers; however, the scientific validity of the recommendations has been questioned and independent review is being conducted. The operation of several federal reservoirs including Flaming Gorge, Blue Mesa, and Ruedi reservoirs has been adjusted to meet the instream f low requirements of the fish. Water and water rights are also being acquired and/or appropriated to provide flows for the endangered fish in a manner consistent with state water law and interstate compacts. However, to date, progress in this area has been slow due to several legal and institutional issues. Until these issues are resolved, the recovery program is evaluating how Colorado's water law might be used to protect flows on an interim or conditional basis. Introduction An understanding of the strategies and problems associ- ated with providing instream flows for the endangered Colorado River fish requires an appreciation of the fish, why they are endangered, and the importance of the Colorado River as a source of water for municipal, indus- trial, and agricultural purposes. The Colorado River yields less water per square mile than any other major river in the United States, yet provides 25 million people with water for municipal, agricultural, industrial, and recreational pur- poses. Water in the basin has been completely divided up between the upper and lower basin states according to interstate compacts made in 1922 and 1948. Dozens of large dams have been constructed to harness the flows in the basin and make those flows available for consumptive (beneficial) use. The river has been altered to control its water to the point that it has been described as the most heavily used, controlled, and fought-over river in the world. Several unique, large river fish evolved in the turbulent, sediment-laden rivers of the Colorado River Basin. Seventy- four percent of the native fish fauna is endemic to the Colorado River. Four of the endemic Colorado River fish-- the Colorado squawfish, the humpback chub, the bonytail chub, and the razorback sucker-are now threatened with extinction due to low numbers and inadequate recruitment. All four are listed as endangered under the Endangered Species Act. Two others, the flannelmouth sucker and the roundtail chub, are identified as candidate species for listing under the Endangered Species Act. These fish are endangered because they have been unable to adjust to the changes in the environment brought about by the activities of man. Changes in streamflow and water temperature, direct loss of habitat due to inundation by reservoirs, blockage of migration routes, and interaction with introduced, non-native fish species (predation and competition) are the primary factors responsible for the decline of these native fish that once ranged throughout the Colorado River Basin. The plight of the native fish in the Colorado River Basin is not an isolated problem. The extinction of three genera, 27 species and 13 subspecies have been documented in North America during the past century (Miller et al. 1989). According to the American Fisheries Society, more than 364 fish in Canada, the United States, and Mexico warrant protection because of their rarity (Williams et al. 1989). Future losses of fish species can only be expected to increase unless the degradation of natural ecosystems is abated. Since 1978, the Fish and Wildlife Service has issued more than 160 biological opinions pursuant to Section 7 of the Endangered Species Act on the effects of water- development projects on the Colorado River endangered fish. These opinions all concluded that the cumulative effects of water depletions from the Upper Colorado River Basin are likely to jeopardize the survival of the endangered fish. In 1984, the Service also produced a draft conserva- 47