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. . INTRODUCTION This biological assessment was prepared in compliance with Section 7 of the Endangered Species Act of 1973, as amended. The Bureau of Reclamation (Reclamation) is considering a recommendation by the Adaptive Management Work Group (AMWG) to conduct one or more beach/habitat-building flows (BHBF) from Glen Canyon Dam between May and July of 1998 as a management activity, if Lake Powell inflow and stage criteria, as well as downstream cultural and natural resource criteria, indicate the flow would be appropriate. Flow criteria have been established for this event, and the Grand Canyon Monitoring and Research Center (GCMRC) is working to complete the natural and cultural resources matrix analysis, Six species identified as threatened or endangered are addressed in this assessment: Kanab ambersnail (Oxyloma haydeni kanabensis), razorback sucker (Xyrauchen texanus), humpback chub (Gila cypha), bald eagle (Haliaeetus leucocephalus), peregrine falcon (Falco peregrinus), and southwestern willow flycatcher (Empidonax trailii extimus). This list of species is based on discussions with the Fish and Wildlife Service (Service) and previous consultations, Impacts of the BHBF flow on endangered species may result from physical displacement, injury, or death; loss or alteration of habitat; reduction in food availability; or alteration of interactions with other species (Bureau of Reclamation 1995), In contrast to the three biological assessments and biological opinions that have been done for Glen Canyon Dam operations since 1994, this biological assessment will not entirely repeat the background information, historical distribution and abundance and life requisite information for the species, but instead attempts to address any new information and focus on the potential impacts of this proposed BHBF on the species and their habitats. Background Occasional high flows are required to restore high elevation sand deposits and characteristic aquatic habitats in the Colorado River ecosystem, such as backwaters. Backwaters are used as rearing habitats by young native fish. Occasional high flows are widely considered to be a primary tool for ecosystem restoration in this system (Stanford et aL 1996, Poff et aL 1997), The Glen Canyon Dam Environmental Impact Statement (GCDEIS) preferred alternative included scheduling BHBFs for the purposes of rebuilding high elevation sandbars, depositing nutrients, restoring backwater channels and providing some of the dynamics of a natural system, The exact season and duration of BHBFs was to be determined through adaptive management, with releases curtailed if monitoring showed detrimental impacts to the ecosystem, 1998 GCD Beach/Habitat Building Flow 4 Biological Assessment