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<br />01813 <br /> <br />., <br /> <br />INTRODUCTION <br /> <br />In September 2002 the Bureau of Reclamation, National Park Service (NPS), and U.s, <br />Geological Survey released an environmental assessment (EA) on proposed <br />experimental releases from Glen Canyon Dam and removal of non-native fish from the <br />Colorado River in Grand Canyon, Arizona (Bureau of Reclamation, NPS, and USGS <br />2002). The experiment was developed by the Grand Canyon Monitoring and Research <br />Center of the US Geological Survey (GCMRC), cooperating scientists, and the Technical <br />Work Group (1WG) of the Glen Canyon Dam Adaptive Management Program <br />(GCDAMP), It was recommended to the Secretary of the Interior by the Adaptive <br />Management Work Group (AMWG), a Federal Advisory Committee charged with <br />providing input to the Secretary pursuant to fuUilJing provisions of the Grand Canyon <br />Protection Act. In December 2002, following tribal consultation, public meetings, and <br />responses to comments by the federal agencies and the public, the Secretary of the <br />Interior concurred with the agencies' finding of no significant impact for the proposed <br />project and agreed that the experiment should move forward, <br /> <br />Pursuant to the Secretary's decision, Reclamation began releases of daily fluctuating <br />flows in January 2003 designed to negatively affect reproduction and recruitment of <br />non-native fish, primarily trout, in the Colorado River below the dam, The objective of <br />this experiment was to reduce the number of non-native fishes that potentially prey on <br />or compete with the federally-endangered humpback chub (HBC, Gila cyplza) in this <br />reach of the river. The primary control mechanisms are disruption of spawning activities, <br />desiccation of embryos in spawning gravels, and reduced survival of young trout after <br />they emerge from spawning gravels due to displacement from favored habitats in the <br />zone of fluctuation between the daily low (5,000 cubic feet per second refs]) and high <br />(20,000 cfs) releases, Non-native suppression releases continued through March 31, 2003, <br />at which time releases returned to those identified in the preferred alternative <br />implemented by the 1996 Record of Decision on the Operation of Glen Canyon Dam, <br /> <br />In January 2003, the Grand Canyon Monitoring and Research Center initiated <br />mechanical removal of non-native fishes from the Colorado River in Grand Canyon in a <br />9.4-mile reach approximately 5 miles above and 4 miles below the contluence of the <br />Little Colorado River, In July 2003, the three federal action agencies produced a <br />supplemental environmental assessment to extend the reach of mechanical removal <br />another 7 miles downstream to a point 73 miles below Lees Ferry. The action was <br />modified to extend the area of mechanical control following a finding of no significant <br />impact by the action agencies and a biological opinion issued by the U,S, Fish and <br />Wildlife Service on August 12, 2003, <br />