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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />'I <br /> <br />002110 <br /> <br />5.0 SUMMARY <br /> <br />The area located within the FERC project boundary at the Williams Fork Reservoir has <br />characteristics that support the presence of erosion activity. The soil existing throughout <br />the Williams Fork Project is primarily sandy or gravelly, which tends to be easily broken <br />down and eroded by both wind and water. Also, wave activity within the reservoir <br />naturally erodes the reservoir bank over time; erosion can be especially active along <br />peninsulas that extend out into the reservoir. The western portion of the reservoir has <br />many peninsulas extending out into the reservoir, while the eastern edge of the reservoir <br />is characterized by tall, steep bluffs. As a result of the characteristics present at this site, <br />a certain level of erosion would be expected to occur naturally, <br /> <br />The majority of the erosion sites identified in this survey are located along the peninsulas <br />present on the western edge of the reservoir. However, the erosion sites posing the most <br />significant risk to resources at the Williams Fork Project are located on the eastern edge <br />of the reservoir. As waves from the reservoir continuously undercut the tall, steep bluffs <br />along the reservoir edge, the upper soi I layers simply fall to the beach and are eroded <br />away. The erosion occurring along the peninsulas does not cut back into the upland areas <br />with the same volume as the erosion occurring along the high bluffs. Due to the rather <br />gradual increase elevation of the peninsulas from tip to upland, erosion at these locations <br />occurs at a much slower rate. Erosion that occurs at the high bluffs can erode more earth <br />material at a higher rate due to its severe undercutting characteristics, <br /> <br />. <br />. <br /> <br />Although the erosion sites identified at the Williams Fork Reservoir were primarily <br />categorized as Class 4 with respect to severity, this must be put into proper context. <br />Class 4 severity is defined in Section 2,1 as loss of 100% of the top soil horizons. The <br />upper soil layers are typically lost in full as a result of the undercutting associated with <br />bank cut erosion. As soil is removed at the base of the reservoir bank by bank cut <br />erosion, the upper soil horizons fall to the beach without the support. These soils are <br />them eroded by wave activity on the beach, Therefore, while 73% of the erosion sites <br />had a severity ranking of Class 4, it would be expected considering that 86% of the <br />erosions sites were bank cut. A severity ranking of Class 4 is normally associated with <br />bank cut erosion, and bank cut erosion is a natural activity occurring along reservoir <br />banks. <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />The primary focus of this survey was to identify those areas where erosional processes <br />pose a significant resource risk. While 73% of the erosion sites had a severity ranking of <br />Class 4, a total of only three erosion sites were determined to pose a significant risk to <br />resources at the Williams Fork Project. These three sites constitute only 4% of the <br />reservoir edge, and are located at the eastern edge of the reservoir (2) and along the <br />Williams Fork River (I). The two erosion sites located along the high bluffs at the <br />eastern portion of the reservoir are encroaching on upland areas adjacent to private <br />property. The one erosion site located along the river is encroaching on the campground <br />that exists adjacent to the river. <br /> <br />Wllhams Fork ReserVOIr <br />Hydroelectric Project <br />JlHlUill)' 2004 <br /> <br />Stelgers Corporation <br />Erosion Survey Repon <br /> <br />Page 9 <br />