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<br />. <br /> <br />BIOLOGICAL ASSESSMENT OF THE OCTOBER 1997 <br />FALL TEST FLOW <br />FROM GLEN CANYON DAM <br /> <br />INTRODUCTION <br /> <br />This biological assessment was prepared in compliance with Section 7 of the Endangered Species <br />Act of 1973, as amended. The Bureau of Reclamation, as directed by the Secretary of the Interior <br />on advice from the Glen Canyon Dam Adaptive Management Workgroup (AMWG), proposes to <br />conduct an October, 1997, Fall Test flow from Glen Canyon Dam, The purpose of this flow is to <br />conserve the fines delivered to the mainstem Colorado River from a series of high flow events in <br />the Paria River which occurred in September and October, 1997, One of the purposes of the <br />Adaptive Management Program is to respond to unforseen events such as described above, and <br />recommend management actions, A major goal of the Record of Decision (ROD) for Operations <br />of Glen Canyon Dam is the preservation of sediment resources in the system. To accomplish this, <br />the AMWG has recommended a 48 hour release at power plant capacity, The Grand Canyon <br />Monitoring and Research Center will orchestrate the monitoring of the results of the proposed <br />action, <br /> <br />Six species identified as threatened or endangered are addressed in this assessment: Kanab <br />ambersnail (n~loma haydeni kanabensis), razorback sucker (Xyrauchen texanu~), humpback <br />chub (.Qi1I~, bald eagle (Haliaeetus leucocE:Phalus), peregrine falcon ~ perejrinull), and <br />southwestern willow flycatcher (pmpidonax ttailii extimus), The list of species is based on <br />discussions with the Fish and Wildlife Service (Service) and previous consultations, Impacts of <br />the 1997 Fall Test flow on endangered species may result from: physical displacement, injury, or <br />death; loss or alteration of habitat; reduction in food availability; or alteration of interactions with <br />other species (Bureau of Reclamation 1995). This biological assessment summarizes the <br />distribution and abundance, life requisites, and potential impacts of the 1997 Fall Test flow on <br />these species and their habitats, <br /> <br />Background <br /> <br />Glen Canyon Dam is located in north-central Arizona in Coconino County one mile west of Page, <br />Arizona (See Fig. 1), Glen Canyon Dam regulates the Colorado River's flow through lower Glen <br />Canyon and all of Grand Canyon, and is managed in accordance with the Grand Canyon <br />Protection Act (1992) and the "Law of the River", <br /> <br />In the Colorado River corridor, flow regulation has resulted in erosion and depletion oflateral <br />sand deposits, particularly in narrow reaches of the river, loss of 50"10 of the native fish species <br />and other changes in the river ecosystem. These impacts focused public and scientific attention on <br />the need for modified operation of Glen Canyon Dam, resulting in a 1995 Environmental Impact <br /> <br />1 <br />