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DRAFT FEASIBILITY STUDY CITY OF OURAY SKYROCKET CREEK DIVERSION December 2000 I. INTRODUCTION The City of Ouray is located in Ouray County in the southwest part of Colorado as shown in figure 1. City of Ouray is situated in the steep sided and nan.ow river valley of the Uncompahgre River and is surrounded on 3 sides by the San Juan Mountains 11sing to over 14,000-feet above sea level (MSL). The City itself is at approximately 8000-feet above MSL and is well known for its scenic mountain vistas. The Skyrocket Creek drainage is located on the east side of the valley near the: northerly entrance to the City of Ouray, immediately above the City hot pool and park (see figure 2). The drainage area for Skyrocket Creek is relatively small, approximately 0.7 square miles. However, due to steep slopes and sparse vegetation, the drainage is subject to cloudburst type flooding and associated debris flows, typically occurring in mid to late summer. Severe debris flows from Skyrocket Creek were experienced in 1927 and again in 1929 resulting in tremendous damage and loss of revenue to the City. Following the severe debris flow in 1929, a diversion channel was bla~ted out of the rock adjacent to the Skyrocket Creek channel to divert flows to the north and away from the public pools. A diversion wall was constructed in the natural channel to direct flows to the new channel. The original diversion wall was constructed of wood and was demolished during a storm event and replaced witl1 a rock and timber wall. This wall was overtopped in 1951 and 1981 with resultant sediment and debris deposited over State Highway 550 and in and around the City pool facility. The wan has been compromised by natural decay of the timbers and periodic damage resulting from storm events, and, in its current state of disrepair, is inadequate to prot(:ct the highway and pools. Risk of overtopping and/or failure in a major storm event is considered high. Failure of the existing wall increases the hazard to the pools as not only would the natural flows and debris be deposited in and around the pool facility but also the wall material (rocks, timber, fencing and miscellaneous construction materials) would be added to the flow. No report of personal injury was made following past facility damage due to Skyrocket Creek flows, but a risk for injury or loss of life exists if advancl~ warning of the flood event and wall failure is not available. The Skyrocket Creek Diversion Project involves removal and replacement of the existing diversion wall to improve public safety and protect public facilities. A study outline dated November 16,2000 was submitted to the Colorado Water Conservation Board (CWCB) as an outline for this feasibility study. The outline was prepared following discussions with CWCB and utilizes existing documentation as much as possible as recommended in the CWCB Guidelines.