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TARGET FLOWS PURPOSES- <br />Summary of noted purposes of USFWS target species flows, annual pulse flows and peak <br />flows for the central Platte River. <br />Source: "Instream Flow Recommendations for the Central Platte River, Nebraska" <br />USFWS-David Bowman, May 23, 1994. <br />Overall Obj ectives: <br />"...(a) recovering habitats ofpresently listed species, (b) preventing the need for listing <br />of additional species, (c) providing sufficient habitat for conservation of native biotic <br />components of the ecosystem." (p.l) <br />Drv Year Flows: <br />"Dry year flows particularly limit the survival and life cycles of aquatic and wetland <br />species, which are the species affected acutely by low flows. The fish community is the <br />dry year target community because it is representative of aquatic species in the ecosystem <br />and some fish species have life cycles of 3 years or less." (p. 2) (Note: weighted usable <br />area curves for fish guilds and data on the relationship between flow and water <br />temperature was considered important.)... "Dry years flows are intended to prevent loss <br />of richness of aquatic species, especially fish and mollusks, and to prevent a major break <br />in wetted width in whooping crane roosting habitat." (p. 3) <br />Wet Years Flows: <br />"Wet year flows were described as channel-forming flows greater that such flows in <br />normal and dry years and as wet meadow sustaining flows. ... Wet meadows and fish and <br />mollusks in the river are the wet year target communities because hydrologic and <br />biologic processes which sustain wet meadows and fish and mollusks are dependent on <br />higher flows. Channel characteristics and riverine community also are maintained by wet <br />year flows. Wet year flows are thought to be more important than normal year flows <br />because wet year flows mimic the historic hydrograph and, in so doing, produce <br />hydraulic and biological effects critical to achieving the goal of conserving the <br />ecosystem." (p. 3) <br />Normal Year Flows: <br />"Normal year flows provide some habitat for all communities in the ecosystem during all <br />the seasons (time periods). Normal flows provide habitat for and sustain populations of <br />most species in the ecosystem between episodes of dry and wet year flows." (p. 3) <br />Pulse Flows: <br />"During normal and wet years pulse flows inundate wet meadows, increase hydrophytic <br />vegetation, scour vegetation, prevent nesting by shore birds at low elevations on <br />sandbars, inundate backwater areas, form sandbars, and form and/or move ice. The <br />maximize the effectiveness, pulse flows must be of sufficient timing, magnitude, and <br />duration to scour seedlings off sandbars and prevent seed germination, as well as to <br />trigger the response of the aquatic community, e.g., spawning fish. Pulse flows are