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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />ES ENGINEERING-SCIENCE <br /> <br />within the scope of this investigation, changes in a site's jurisdictional designation <br />may occur with more intensive site investigation of vegetation, soils, and ground <br />water conditions. <br /> <br />Wetland EfJects <br /> <br />The acreage of probable jurisdictional wetlands inundated by each scenario is <br />snmm'''ized in Table 1. Affected areas of wetlands range from a minimum of <br />approximately 31.7 acres with Scenario B to a mllnmum of about 41.3 acres with <br />Scenario D. Scenario A would result in an increase in wetland acreage as is <br />discussed below. Inundated wetland acreage increases are generally proportional to <br />the volume of new water stored, as more floodplain wetlands are flooded with <br />higher pool elevations. Greater storage volumes move the inundation elevation <br />progressively and rather uniformly up the headwater areas. These areas have <br />relatively uniform distributions of wetlands. More wetland acres would be <br />inundated in the Bear Creek floodplain than in the Turkey Creek floodplain <br />because of the larger proportion of existing wetlands present along Bear Creek. <br />Losses of wildlife habitat functional values would be considered significant as these <br />values would decline in proportion to wetland losses. Aquatic life habitat functional <br />values are likely to increase (at least temporarily) for some species as new aquatic <br />structure is added to an enlarged lake. Additional nutrients are likely to be released <br />into the water column as plant materials decay and the upper layers of the existing <br />soils release inorganic chemicals into the surface waters. If watershed erosion rates <br />continue at present levels, it is anticipated that new willow wetlands will form on <br />alluvial fans at the mouths of both creeks. A thin band of perimeter willows may <br />reestablish itself around the lake's shoreline, depending on the relative stability of <br />each scenario's new pool elevation. <br /> <br />Scenario A would result in a lower pool elevation of approximately 4 feet that <br />could encourage development of new wetlands on parts of the reservoir's bottom <br />that are currently flooded. The most likely areas of wetland development would <br />occur on the exposed surfaces of the submerged alluvial fans now forming at the <br />mouths of both creeks. The area, acreage, and types of new wetlands would be <br />influenced by the slope of the shoreline to be exposed and the extent and duration <br />of future water level drawdowns compared to the existing permanent pool elevation. <br />Some new wetlands could also develop along the lake's shoreline in a fashion very <br />cimilllT to the shoreline wetlands currently existing along the present shoreline. If it <br />is assumed that the newly exposed shoreline would have slopes similar to the <br />existing shoreline slopes, then is it estimated that approximately 3 to 5 acres of new <br />wetland could develop because of Scenario A. <br /> <br />Riparian Area EfJects <br /> <br />Acreages of riparian areas inundated by the scenarios are also snmmllrized in <br />Table 1. Affected acreages range from a minimum of approximately 3.1 acres with <br />Scenario B to a maximum of approximately 9.2 acres with Scenario D. Scenario A <br />would not cause inundation of any riparian areas. Inundation characteristics and <br />relationships described for wetlands also apply to riparian areas. The total <br />inundated acreage of combined wetland and riparian areas would be approximately <br /> <br />-9- <br /> <br />B16-3-3 <br />