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<br />l. <br />i <br /> <br />GRAND CANYON NATIVE FISH MANAGEMENT <br /> <br />17 <br /> <br />.' <br />~' <br /> <br />opinion, with reasonable and prudent alternatives, was submitted to Reclamation in August <br />of 1987, but the two agencies subsequently agreed to deveIop seven Conservation Measures <br />in lieu of reasonabIe and prudent alternatives. <br /> <br />I <br /> <br />. In JuIy of 1989, the SecretarY of Interior agreed to National. Environmental Policy Act <br />evaluation of the operation of Glen Canyon Dam and the preparation of an Environmental <br />. Impact Statement (EIS). Although it was recognized that much of the research conducted <br />under the Conservation Measures would not be compIeted, the EIS was scheduled to be <br />finished in 24 months and USFWS agreed to render a biological opinion on the preferred <br />alternative put forth in that document. <br /> <br />.. <br /> <br />"" <br /> <br />,.., <br /> <br />Summary and Conclusions-The operational scenario described above has sufficient scope <br />and flexibility to utilize the dam as a powerful tool to effect enhancement of the native fish <br />community, a1Iow establishment of a balance between native and non-native fishes, and <br />benefit other natural resources of Grand Canyon. We are confident, within the limitations <br />of our imperfect knowledge of species and processes, that return of the CoIorado River <br />below Glen Canyon Dam to a semblance of its natural state through creative changes in <br />discharge, thermal regime, and sediment augmentation will ultimately enhance native fishes <br />in Grand Canyon. Our recommendations are not to be viewed as a triaI-and-error approach <br />to ecosystem management. Rather, once capability to impIement these major changes is in <br />place, operational flexibility will become the key to optimizing conditions for all resources. <br />Within this context, water management (exclusive of emergency situations and as otherwise <br />cOnstrained by law) will be responsive to requirements of the native ichthyofauna. <br /> <br />..~ <br />::,: <br /> <br />;~ <br />~'1 <br /> <br />< <br /> <br />c ~~, <br /> <br />. .,.:!~- <br /> <br />;"". <br /> <br />We '-envision . an impIementation schedule that emphasizes dynamic flexibility and <br />experimentation in all phases of operation, coupled with. systematic, -,programmed antI- . <br />opportunistic monitoring of changes in downstream habitats and biota. Discharge regimens <br />should initially be fixed (within applicable legal constraints but also with the priority of <br />native fish management) to eliminate daily fluctuations and mimic the natural seasonal <br />hydrOgraph for a period of years adequate to document downstream enhancement of the <br />native fish community. Contemporaneous research on seasonal thermal mOdification via <br />MUS shouId be instituted and conducted as quickly as possibIe to determine the advisability <br />of this action. Finally, sediment augmentation couId be brought on Iiite tocompIete the steps <br />toWard restoration of natural habitats and the native fish community. The appropriate <br />combination of hydroIogy, temperature, and sediment that optimizes conditions for native <br />fish. cannot now be predicted, but will be determined only by creative experimental <br />manipulations, a process that may take decades to resoIve. Status assessment of native fishes <br />WOuld be directed continuously into a feedback loop to water managers to allow integration <br />of operations with species requirements: <br /> <br />';; <br />''i, <br /> <br />>..' <br />1--';. <br />~~. <br /> <br />A <br />. <br />,;.- <br />~~ <br />/;1-. <br />tf! <br />..:-". <br /> <br />\ <br />