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<br />e1 <br />, <br />, <br />j <br /> <br />-, <br />, <br /> <br />Chapter III - Background Information <br /> <br />,-..... <br />1 <br />j <br />, <br /> <br />.-..1 <br /> <br />A. Previous Studies <br />There have been four hydrologic studies performed for the dam which include the study <br />performed by Bruns in 1979, by Rocky Mountain Consultaots in 1984, aod by the SEO in 1995, aod. <br />by Ed A. Toms, Consultant which is presently under review by SEO. The first three studies <br />concluded that the spillway was not adequate to pass an inflow design flood of 50 percent of <br />probable maximum precipitation (PMP). The fourth study used an incremental damage analysis <br />(IDA) to justify a 100-year spillway capacity, instead of the 50 percent PMP flood event otherwise <br />required by the SEO. Based on the IDA results, the spillway capacity will have to be increased from <br />the present capacity of 450 cfs to the 100-year flood capacity of 4,393 cfs. The hydrologic <br />assessment is presently under review by the SEO. <br /> <br />-'1 <br /> <br />"1 <br /> <br />B. Study Area and Existing Facilities Description <br />Ryan Gulch Dam and Reservoir are located in southwest Loveland as shown in Figure I-I. <br />Ryao Gulch Dam is classified under SEO guidelines as a Small, Class II structure, with a height of <br />31.9 feet (GH 0 to crest of emergency spillway) impounding 976 AF at the spillway crest. The Dam <br />aod reservoir was constructed in April 1904. The dam crest is 894 feet long. The spillway is a <br />natural channel located on the right abutment. The reservoir was restricted on February 15, 1978, <br />due to inadequate spillway capacity. The reservoir was restricted 8 feet below the dam crest to gage <br />height 27.6 feet (645 AF). <br /> <br />-. . ~ <br /> <br />~J <br /> <br />1 <br />.J <br /> <br />The source of water for the reservoir is from runoff and groundwater seepage, from the 12.36 <br />square mile watershed. The reservoir is located in section 27, township 5 north, range 69 west of <br />the 6"' P.M.. <br /> <br />-, <br />~ <br /> <br />; <br />, <br /> <br />C. Water Demands <br />The purpose of this project is strictly limited in scope to the rehabilitation of Ryan Gulch <br />Dam. No additional water supplies will be developed in connection with this project. No new or <br />increased diversions will be made and no additional storage capacity will be created at the reservoir. <br /> <br />C\WORK'.PROlECTSIRYAN\FEASREPORT\RYA1"RPT DOC <br /> <br />5 <br /> <br />Jan\l.3ry ]2. 1999 <br />