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<br />~~O <br /> <br />III, Study Background/Rationale: <br /> <br />The Floodplain Habitat Restoration Program seeks to restore and/or <br />enhance the floodability of riparian habitats tb benefit endangered <br />fishes and assist in recovery. The more practical, cost-effective <br />nonflow alternatives for enhancing floodability include breaching <br />levees and/or lowering floodplain elevations, To increase <br />likelihood of success and minimize potential adverse impacts. pre- <br />construction surveys and design planning are recommended, <br /> <br />To date, floodability assessments and site design/engineering have <br />been done for the U.S, Fish and Wildlife Service's Ouray National <br />Wildlife Refuge (Johnson Bottom, Leota Bottom, Wyasket Lake, <br />Sheppard Bottom, and Old Charley Wash): the National Park Service's <br />Canyonlands National Park (Millard Canyon, Queen Anne Bottom, <br />Anderson Bottom, Bonita Bend, Unknown Bottom. and Valentine <br />Bottom)(FLO Engineering 1996); and BLM wetlands (Bonanza Bridge, <br />Horseshoe Bend, The Stirrup, Baeser Bend, and Above Brennan)(FLO <br />Engineering 1997). <br /> <br />Data collected on the Ouray Refuge indicated that 22,800 cfs <br />(Jensen) would be needed to inundate 5,000 acres of floodplain <br />habitat, If levees were breached, however" the same amount of <br />habitat could be inundated at 12,000 cfs, In Canyonlands, data <br />suggested that flows in excess of 39,000 cfs (Green River, Utah) <br />would be necessary for the river to leave' its banks and flood <br />adjacent terraces, <br /> <br />Where private landowners are interested in selling fee or easements, <br />floodability assessments are prudent for determining the amount of <br />floodable habitat the Program would be buying for acquisition' <br />dollars, On both private and public lands where it is determined <br />that levee removal or excavation could enhance floodability, and <br />where landowners and managers are willing to cooperate, floodability <br />assessments are prudent for determining the amount of floodable area <br />the Program will be getting for construction dollars,' <br /> <br />Other considerations being addressed by this work help ensure that <br />acquired and restored habitats will: <br />1, enhance survival, growth and recruitment of young razorback <br />suckers: <br />2, ,maximize inundation, to make the' best use of existing (and <br />anticipated future) flow regimes; <br /> <br />2 <br />