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the importance of maintaining the structure and functions of the Platte River processes. <br />To reduce the decline of Platte River endangered species habitat, measures must be taken <br />to improve: a) hydrologic processes that reincorporate sediment transport and vegetation <br />removal; b) open channel and sandbar creation and maintenance for roosting, nesting and <br />wading birds, as well as instream aquatic habitat diversity; c) aquifer recharge for wetland <br />maintenance; d) backwater flooding for nutrient cycling, fish spawning and distribution; <br />and e) water temperature and other water quality factors. <br />Cumulative depletions of normal high flows in the spring, which are elemental to the structure <br />and function of the Platte River ecosystem, include: <br />Reduction in frequency and duration of normal high flows in Februarv/March and <br />Maw /June. These reductions adversely affect the formation and maintenance of wide, <br />alluvial channels; promote seedling establishment and expansion of riparian woodland <br />along the river. Vegetation of sandbars and attachment of sandbars to river banks reduces <br />amounts of roosting habitat available for whooping cranes during migration, and nesting <br />and feeding habitat for terns and plovers. <br />�land Depletions to high flows adversely affect wet meadows adiacent to the river. In February <br />March, rising ground water levels thaw the soil and initiate biological responses of <br />z <br />� soil organisms. Flow depletions during May and June incrementally reduce groundwater <br />�IV levels and decreases the frequency and duration of soil column saturation. Groundwater <br />levels during the growing season are important to maintaining the long -term biological <br />µ� functions of wet meadows for listed species. Incremental and cumulative changes of wet <br />meadows toward more xeric conditions adversely affects productivity of aquatic and semi <br />aquatic wet meadow communities, and contributes to fragmentation of the habitat via <br />�r conversion of wet meadows to other uses. <br />Decline of sediment load from reductions in magnitude frequency and duration of normal <br />high flows adversely affect sediment transport from the watershed and through the river <br />system. This transport of sediment is a principle benefit of spring pulse flows in alluvial <br />rivers such as the Platte. Reservoirs and irrigation canals have trapped sediment, <br />reducing sediment load in the river. Supply and transport of sediment through the system <br />are essential to sustain the alluvial channel habitats used by endangered species and <br />necessary for maintenance of a diverse channel morphology. <br />Assessment of Program Impacts <br />The above sections described the influences of water development on the habitat of the target <br />species, and efforts being made to mitigate those impacts. The following section identifies, by <br />species, the questions needing resolution, i.e., the basis for the Service's evaluation of Program <br />impacts. The questions are consistent with and supported by elements of the recovery plans for <br />the target species, elements of the species listing determinations, elements of the critical habitat <br />designation, the general factors of species listing /delisting expressed by Service policies, Platte <br />4 <br />