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<br />1.0 Purpose and Need for Action <br /> <br />1.1 Proposed Action. The Corps of Engineers and the local sponsor, the city of <br />Ouray, propose to rehabilitate an existing streambank on Skyrocket Creek. <br /> <br />1.2 Need for Proposed Action. Since the city of Ouray, Colorado, was founded in <br />1875, periodic debris flows have damaged buildings, roads, water systems err <br />sewer systems. Skyrocket Creek is one of eight creeks in the area whose flow'% . <br />directly affectX the city of Ouray. '-= <br /> <br />Debris flows occur when water falls large elevations, a 2,800-foot elevation <br />drop in the case of Skyrocket Creek, and picks up and combinestfrle silt and clay, <br />sand, gravel, boulders, and dislodged timber (Jochim, 1986}. ll'the Ouray area, <br />these flows usually occur in response to intense summer thunderstorms after a <br />period of several years during which detJris accumulates at the base of the <br />hillslopes in the primary drainage channels. <br /> <br />In 1929, Ouray County rerouted Skyrocket Creek to the north to reduce the <br />risk to the Hot Springs Park (Figure 1). A new channel was blasted through the <br />bedrock on the north side of the creek, and a wooden diversion structure was built <br />across the original channel. This was done to protect the downstream highway <br />and city facilities from debris flows originating in the upstream watershed. In July <br />1981, a debris flow from Skyrocket Creek breached the diversion and inundated <br />the Hot Springs Park (Jochim, 1986). <br /> <br />In order to protect the downstream facilities consisting of U.S. Highway <br />550, the community's natural hot springs aquatics center, visitor center and <br />children's fishing pond, a 6-inch water line, and a 12-inch sewer collector line and <br />manholes, the current diversion needs to be replaced. The diversion ~I'e-~ <br />consists of earth and rock fill in the natural bedrock drainage way, topped by <br />timbers that have been displaced. Remnants of cabling, chain link fencing, and <br />sawn timbers that once comprised a portion of the structure have toppled into the <br />downstream drainage way. If the structure is not replaced, the almost vertical <br />slope of the channel as it comes off the mountain will result in very fast and <br />dangerous water, mud, and debris flowS for even moderate precipitation events. <br /> <br />1.3 Project Location. Skyrocket Creek, an intermittent tributaLY ~) ~e -tlv C"';:~i\JJ <br />Uncompahgre River, is located immediately north of~"eJ\ci~'of C'Jur'1lY;' -'f-ne- ~ \;0.0 \ I " <br />Skyrocket Creek diversion is located on the left bank of the creek channel at an <br />elevation of about 8,000 feet. The creek channel drains an area of about 0.7 <br />square mile. <br /> <br />1 <br />