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<br />01186 <br /> <br /> <br />vi Executive Summary <br /> <br />Executive Summary <br /> <br />The Grand Canyon is one of the Nation's treasures. The Department of the Interior is <br />proposing a series of experimental actions, some of which involve modifying the <br />operations of Glen Canyon Darn, which is located upstream of the Grand Canyon, to <br />improve the condition of the habitat within the Grand Canyon and the species that have <br />their home in the canyon. This proposed action was deemed necessary by the GCDAMP <br />because endangered species and sandbars in the Grand Canyon have not responded as <br />well as predicted to past management actions regarding the operation of Glen Canyon <br />Darn. The proposed actions, detailed in the accompanying report, are the product of <br />years of scientific study and would implement the recommendation of an independent <br />advisory committee that has been studying the natural and cultural resources of the <br />Grand Canyon since 1997. The proposed actions presented in this report are multi- <br />faceted and complex, and have been designed to protect both the endangered species <br />and the important beach habitat found in the Grand Canyon. <br /> <br />The 1996 Record of Decision (ROD) on the Operation olGlen Canyon Dam Final <br />Environmental Impact Statement (FEIS) modified the operation of the darn in an effort to <br />protect downstream resources. An adaptive management program was established by <br />the ROD to monitor the effects of this change, perform research necessary to measure <br />whether these resource protection objectives were met, and make recommendations to <br />the Secretary of the Interior. <br /> <br />Since 1996, the non-native trout population in the Grand Canyon has tripled, the <br />endangered humpback chub (HBC) population has declined precipitously, and tributary <br />sediment inputs are not being conserved as expected in the FEIS. These trends are <br />contrary to the expectations of the FEIS and the goals of the adaptive management <br />program. If no actions are taken and current operations continue, these trends are <br />expected to continue. <br /> <br />An experiment consisting of a combination of Glen Canyon Darn releases and <br />mechanical removal of non-native fish is proposed to determine if these proposed <br />actions can reverse current trends. The proposed darn releases are intended to conserve <br />sediment inputs from the Paria River and reduce spawning and recruitment success of <br />non-native trout. Mechanical removal of non-native fish is proposed in order to remove <br />trout who feed on young chubs near the confluence of the Little Colorado River (LCR), <br />which is the only known stream in Grand Canyon where the endangered humpback <br />chub reproduces and survives to adulthood. <br />