Laserfiche WebLink
Hozizontal points were taken in Colorado State Plane, Central Zone with NAD83 <br />datum. However, since this survey was not tied into any existing control, compatibility <br />with the State Plane coordinate system can only be assured to around 15 feet. <br />A rover GPS unit was used to perform the topographic survey. Points were taken at <br />a roughly 50-foot grid. All points were taken at ground level (bottom of the reservoir), <br />even at places where several feet of snow and/or ice had to be removed to get an <br />accurate reading. Points were taken to several feet above the top of the spillway <br />elevation to ensure an accurate full-capacity reading and to provide as much <br />topographic information as possible in case GPS positions could not be gathered in <br />some places. Additional points were taken at significant contour breaks, such as the <br />streambed, the hole with pooled water, and the mound in the southwestem part of the <br />reservoir. All of these features are shown in Figure 1. The =nflow stream was also <br />surveyed to the south to an elevation a few feet higher that than the top of the spillway. <br />There was an area of around 11,000 square feet of standing water at the northern <br />end of the reservoir (Figure 1). Accurate measurements of the reservoir bottom in this <br />area were taken by standin� on the several inches of ice covering the pool. Holes were <br />chipped in the ice and a surveyor's rqd was lowered to measure the depth of the pool. <br />A topographic map was generated from the GPS survey points by J&K usinD Digital <br />Terrain ModelingTM software produced by Soft Desk, Inc. This map, at a scale of 1 <br />inch equals 60 feet, is presented as Attachment A. <br />The topographic information was imported into the QuickSurf"`' surface modelina <br />proDram, along with the original control points and break lines. A"surface" of the <br />bottom of the reservoir was made with a triand lated grid, as shown in Figure 2. <br />Reservoir volumes were then determined by calculating the difference between the <br />bottom surface and a plane rep�esenting a specified water elevation. These calculations <br />were run for all elevations based on one-foot elevation drops from the top of the <br />spillway elevation. <br />RESULTS <br />Reservoir volumes at different water levels are shown in Table l. <br />• The maximum capacity of the reservoir is 227.0 acre feet. <br />• The capacity at normal pool elevation is 162.1 acre feet. <br />• The dead storage (volume that cannot be drained from the basin) is 0.9 acre feet. <br />The surface area of the reservoir is 17.3 acres at maximum capacity and 15.1 acres <br />at normal water level. The cross sections in Figures 3 and 4 show the bottom <br />topography of the reservoir and the normal pool elevation. <br />Normal water level elevation was estimated from observations made in the field <br />during the survey and was based on water lines, extent of vegetation, and debris on the <br />dam. The normal pool elevation is around four fee[ below the top of the spillway, at <br />elevation 994. <br />02?/730555! 1. DOC -2- 12/12/96 <br />