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Colorado Division of Water Resources <br />Office of the State Engineer e® <br />Dam Safety <br />Memorandum <br />To: Alan Martellaro, Division Engineer <br />File <br />From: Jackie Blumberg, Division 5 Dam Safety <br />Date: December 21, 2017 <br />Dam Name: Copper Spur <br />DAMID: 350xxx <br />Subject: Spillway Adequacy Memo <br />Background <br />Division of Water Resources <br />Department of Natural Resources <br />This memorandum describes analyses performed to determine hydrologic adequacy <br />for the proposed Copper Spur dam spillway, which is comprised of a riprap lined, 1 - <br />foot deep, 15 -foot bottom width channel with 3H:1V sides. The tributary area for <br />Copper Spur dam is greater than the upper limit of the guidance table presented on <br />the Notice of Intent form to construct a non -jurisdictional structure. Copper Spur dam <br />would be constructed within the breached McCoy reservoir, which is located within <br />Routt County, at 39.9383291 latitude and -106.643891 longitude. <br />Pertinent dam information is summarized below. <br />Table 1. Copper Spur Dam Information <br />Copper• <br />Dam <br />Information <br />Parameter <br />Value <br />Parameter <br />Value <br />Jurisdictional Height <br />9.8 feet <br />Tributary Area <br />4.06 sq -mi <br />(2,598 acres) <br />Freeboard <br />NA <br />Size <br />Minor <br />Normal Storage <br />(at Emergency <br />8.33 acre-feet <br />Hazard Class' <br />NPH <br />Spillway) <br />Maximum Storage <br />10.29 acre- <br />Hazard Class Date <br />NA <br />(at Dam Crest) <br />feet <br />Reservoir Surface Area <br />(at Emergency <br />1.87 acres <br />Dam Type <br />RE <br />Spillway) <br />' Hazard rating is assumed. An open floodplain exists directly downstream from the dam, as does Yarmony reservoir, which is <br />situated 1.4 miles downstream. A formal hazard study has not been prepared. <br />OF' �0� <br />�� <br />215 Center Drive, Glenwood Springs, CO 81601 P 970.945.5665 www.colorado.gov/water ye�"� -� o <br />��r <br />{` 1876 � <br />