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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Chapter m - Background Information <br /> <br />A. Study Area Description <br /> <br /> <br />Left Hand Valley Reservoir is the largest and most important reservoir in the Left Hand <br /> <br /> <br />Ditch Company system. The reservoir serves as a source for direct releases of storage water, as an <br /> <br /> <br />exchange vessel, and as a regulating reservoir for smoothing out diversions by the twelve lateral <br /> <br /> <br />ditches served by the Company. Five of the twelve ditches can be served directly by the reservoir <br /> <br /> <br />through its outlet ditch. The seven upper ditches in the system benefit by diverting water from Left <br /> <br /> <br />Hand Creek in exchange for reservoir releases made to the lower ditches. <br /> <br />. Left Hand Valley Reservoir is an off channel reservoir located in the upper drainage basin <br />of Dry Creek, a tributary of St. Vrain Creek, just east of the first foothills of the Front Range. The <br />reservoir is located in Sections 29, 30, 31 and 32 of Township 3 North, Range 70 West of the 6th <br />P.M., Boulder County, Colorado as shown in Figure III-I. Water to fill Left Hand Valley is <br />diverted from Left Hand Creek and carried through a canal to the reservoir. The reservoir is formed <br />by two dams each approximately 45 feet high and 450 feet long, has a normal full capacity of 1,624 <br />acre-feet, and a surface area at the normal high water line of 113 acres. The existing spillway is <br />located in a cut in the south abutment of the north dam and is trapezoidal in cross section with a 30- <br />40 foot bottom width and 2: I side slopes. The spillway flowline crest elevation is approximately <br />5,351 feet and the tops of the dams are at approximately 5,358 feet. The existing spillway has a <br />capacity of 2,200 cfs for a reservoir water surface elevation of 5,3 58 feet. <br /> <br />Left Hand Valley Reservoir is located approximately 3 miles north of the City of Boulder, <br />Colorado and approximately 1.5 miles west of Boulder Reservoir. Just south and east of the <br />reservoir is a residential county development of approximately 157 homes and a golf course. These <br />facilities cause the dams to be classified as Class I, high hazard dams. Because of the height of the <br />dams and the capacity of the reservoir, the dums are classified as intermediate in size. <br /> <br />8 <br />