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Gypsum Loan Feasibility Outline <br />CWCB Water Project Loan Program <br />Page 20 of 33 <br />2.4 Proiect Descrintion - Analvsis of Alternatives & Selected Alternative <br />LEDE Reservoir is located in the Gypsum Creek drainage in Eagle County, Colorado; <br />approximately 17 miles south-southeast of the Town of Gypsum. Water is diverted into <br />LEDE Reservoir via a 2,800 foot long ditch, LEDE Ditch, from Antones Cabin Creek. <br />The current reservoir capacity is 431 acre-feet, 428.5 acre feet of live storage and 1.8 acre <br />feet of dead storage. The reservoir ha.s a surface area of approximately 25 acres. <br />LEDE Reservoir Dam is a homogenous earth embankment with a rock toe drain. <br />According to records of the Colorado Office of the State Engineer (SEO) and <br />construction drawings, the dam was originally constructed to a height of about 15 feet <br />starting in 1931, and raised to the present structural height of 39 feet in about 1940. The <br />present hydraulic height of LEDE Reservoir Dam is 33.5 feet, the crest length is about <br />340 feet, and the crest width varies from 8 to 12 feet. The reservoir maximum pool <br />elevation is 9524, as estimated from the USGS topographic quadrangle map. <br />The e~sting spillway is an unlined 16 foot wide open-cut channel on the right abutment, <br />with concrete grade control structures. The outlet works consists of an 18 inch riveted <br />steel pipe and corrugated metal pipe (CMP) below the dam, regulated by a sloped gate. <br />The diversion ditch, dam, and reservoir are located on U.S. Forest Service Land and are <br />operated under the terms of the Special Use Permit in Appendix 1. The dam is presently <br />classified as a small (20 to 50 feet high, 100 AF to 4000 AF storage.). The Hazard <br />Classification has yet to be completed at this time but is assumed to be High to remain <br />conservative. <br />The LEDE Ditch diverts water from Antones Cabin Creek, aka Lost Creek. The ditch is <br />approximately 2800 feet in length with the first 860 feet of the ditched piped using 30" <br />diameter CMP. A 30" wheel gate and 10 feet of 30" CMP were installed in 2007 to <br />improve the control of water into the ditch. The control gate is located approximately <br />1900 feet downstream from the head of the ditch. <br />A previous evaluation of the LEDE reservoir was done for dam safety purposes. <br />Calculations for that evaluation were based on the 1999 dam safety rules and regulations <br />and are included herein. The dam safety rules were updated as of 2007. <br />The Inflow Design Flood event (IDF) for the LEDE Reservoir is based on the Probable <br />Maximum Precipitation (PMP) and calculated to be approximately 5400 cfs (See <br />Appendix 5). The spillway was required to pass an IDF based on 75% PMP or 4050 cfs <br />with a 5 foot freeboazd under the 1999 dam safety regulations. It was estimated that the <br />existing spillway capaci.ty was 883 cfs, consistent with the 100 yr design flow and a Class <br />3 Dam. Under the current 2007 dam safety regulations, the dam is conservatively <br />classified as a Small High Hazard Dam. The spillway IDF, adjusted for an average <br />drainage basin above 8000 ft., would be based upon 70% PMP or 3780 cfs. There is a <br />small difference in the spillway IDF between the 1999 and 2007 regulations. The LEDE <br />