Laserfiche WebLink
<br />LONG HOLLOW RESERVOIR <br />FEASIBILITY STUDY <br /> <br />1.0 EXECUTIVE SUMMARY <br /> <br />The Long Hollow Reservoir (LHR) is located in southwest La Plata County, approximately 22 <br /> <br />miles southwest of Durango, Colorado in Sections 29, 32, and 33, Township 33 North, Range 12 <br /> <br />West of the New Mexico Principal Meridian. The private parties shown on Exhibit 3.1-1 hold <br /> <br />ownership of the dam and reservoir site. <br /> <br />Feasibility level drawings for a 5,400-acre-foot (AF) reservoir are presented in Exhibits 3.1-1 <br /> <br />through 3.1-5 at the end of this volume in Il-x-17-inch format. The drawings, which will be <br /> <br /> <br />referred to throughout this report, were developed by combining the most advantageous <br /> <br />alternative for the dam and appurtenant structures based on available data. The reservoir will fill <br /> <br />to the 5,400-AF capacity in 4 of 14 years, with an average fill of 3,540 AF per year. LHR will <br /> <br />release all or nearly all stored water in 10 of 14 years. A 300-AF La Plata River Compact <br /> <br />(Compact) reserve pool in LHR will be used to deliver water to New Mexico during the mid- <br /> <br />summer low-flow period when the La Plata River in Colorado must be administered as a split <br /> <br />fiver. <br /> <br />The Rules and Regulations for Dam Safety and Construction from the Office of the Colorado <br /> <br />State Engineer (SEO) classifies dams according to their hazard and size (Department of Natural <br /> <br />Resources 1988). The regulations designate a dam for which loss of human life is expected in <br /> <br />the event of a failure as a Hazard Class I dam. Long Hollow dam will be a hazard Class I dam <br /> <br />and is in the large-size classification because it will have a height greater than 100 feet and a <br /> <br /> <br />reservoir capacity greater than 1,000 AF. <br /> <br />The SEO's regulations require that the inflow design flood (mF) for determining the spillway <br />capacity of a Class I large-size dam shall be the probable maximum precipitation (PMP). The <br />IDF flow predicted for LHR is based on a 6-hour local storm that produces a peak discharge of <br />39,600 cubic feet per second (cfs). The resulting spillway capacity would be 32,700 cfs. <br /> <br />991-077.120 <br />March 2005 <br /> <br />Wright Water Engineers, Inc. <br /> <br />Page 1 <br />3/21/20059:50 AM <br />