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rates are requested during daylight hours for the months May through September. The <br />high flows are requested for three selected weekends (2 -3 days), as determined by the <br />Town and coordinated with the release schedule from Dillon Reservoir. The low flow <br />represents the minimum flow required for any recreation on this reach of the River. The <br />high flow, for a total of nine days each year, represents the minimum flow required for a <br />whitewater experience utilizing kayaks. <br />Structures <br />The course will consist of three control structures as shown in Exhibit A -2. The <br />structures are rock dam and drop structures that will direct the flow to pass through an <br />opening of controlled width to create a pooling effect upstream and adequate depth for <br />passage of watercraft. The structures are designed to control both low flows and high <br />flows. Low flows will pass through a narrow opening in the structure. Under higher <br />flow conditions, the water surface will rise, and flow will pass through a wider opening <br />(See Exhibit A -3). <br />Under the high -flow rates, the energy of the flow as it passes through these structures will <br />create a wave, or hydraulic jump effect, providing the conditions for a whitewater <br />experience. The general geometry and configuration of the structures are shown in <br />Exhibits A -3, A-4, and A -5. <br />SECTION 3 <br />ENGINEERING BASIS FOR REQUESTED LOW FLOW <br />Low flow rates are requested for passage of various type of watercraft, including rafts, <br />canoes, kayaks, and inner tubes, from May 1St to September 30`s. The basis for the 100 <br />cfs flow rate is to provide a minimum depth of 2 feet and a minimum width of 10 feet, to <br />allow and facilitate recreational boat passage. The control structures have been located <br />and sized to maintain this flow and depth. These flows and depths were recommended by <br />Mr. Gary Lacy, P.E., Recreational Engineering and Planning, Boulder, Colorado. <br />A simple weir equation was applied to determine the flow required to maintain these <br />depths and flows: <br />Q = 3.3 * L * h 112 (Equation 1) <br />where L is the width of the opening (10 feet) and h is the depth (2 feet) of the flow <br />through the structure, thereby resulting in Q = 93.3 cfs. In order to provide for a margin <br />of safety for the 2 feet depth, a flow of 100 cfs is requested. <br />CADocuments and SettingsWRichards\Local Settings \Temporary Internet Fi1es \0LK722\RICD Eng Report (3).doc 2 <br />