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<br />The main impacts from this alter~ative would be the drastically changed <br /> <br />aesthetic appearance of the downstream face of the dam. There would be a total <br /> <br />loss of vegetation from the dam face. ~is is not considered to have significant <br /> <br />impacts on wildlife populations except for small mammals and ground-nesting <br /> <br />birds, since the vegetation is essentially nonnative, and these populations are <br /> <br />not high. <br /> <br />One could expect to experience problems downstream from runoff during <br /> <br />periods of intense rainfall. The do~stream face is currently vegetated and <br /> <br />runoff is therefore minor. In addition, in the case of a significant overtopping <br /> <br />of the dam during a major flood event, ttlis could lead to serious localized flood <br /> <br />problems in downstream areas. Such flow$ could also cause localized bank erosion <br /> <br />and loss of streamside vegetation if the runoff was of long duration. <br /> <br />As with the abutment spillway alternatives, no impacts to any federally- <br /> <br />listed threatened and/or endangered plant or animal species is expected for <br /> <br />reasons stated earlier. <br /> <br />ALTERNATIVE 7 - RAISE DAM CREST <br /> <br /> <br />This alternative involves raising r.he dam crest through (1) the addition of <br /> <br />a reinforced concrete wall to the required height along the crest of the dam. or <br /> <br />(2) the placement of additional earth on the crest and downstream face of the dam <br /> <br />to the required height. <br /> <br />Environmental impacts would result from the stripping off of the existing <br /> <br />grass cover to facilitate the construction of these two proposals. This should <br /> <br /> <br />not cause any significant negative ecological impacts I however. since these <br /> <br /> <br />grasses are predominantly nonnative and represent low quality habitat from a <br /> <br /> <br />species and locational perspective. <br /> <br />Construction of the reinforced concrete wall could detract from the existing <br /> <br />aesthetic values of the project by effectively blocking motorists' views of the <br /> <br /> <br />reservoir or the downstream area as seen from the road on the dam crest I <br /> <br /> <br />depending on the location and height of the wall, In addition, it is possible <br /> <br /> <br />that the extensive vertical surface presented by the wall could encourage vandals <br /> <br />62 <br />