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was enlarged in the early-1900s by the New Ish Ditch Company. The reservoir is not managed <br />for flood control or hydropower operations. <br />Ish Reservoir is impounded by an earthen embankment. The reservoir spillway is located on the <br />northern and eastern side of the reservoir near the Boulder County-Larimer County line, at gauge <br />height 37.6 feet, above the storage capacity of the reservoir. Releases from storage are made <br />separately through outlet gates on the north side of the reservoir. Boulder Larimer Ditch <br />Company shareholders receive storage water via the Old Ish Ditch. New Ish Ditch Company <br />shareholders receive storage water via the New Ish Ditch, which meets the bypass ditch, <br />described above, about one-half mile below the splitter box. <br />Capacity: <br />Total Storage: 7,128 ac-ft <br />Active Storage: 7,128 ac-ft <br />Dead Storage: 0 ac-ft <br />Area/Capacity Data: The Boulder Larimer Ditch Company provided an elevation-area- <br />capacity curve. A subset of the data points are provided in Table 1. <br />Table 1 <br />Ish Reservoir <br />Stake -Area -Capacity Curve <br />Elev. Area Capacity <br />(ft) (Acres) (Ac-Ft) <br />6 52.38 7.57 <br />8 92.70 182.23 <br />10 118.42 384.51 <br />12 141.67 635.07 <br />14 169.98 936.65 <br />16 193.77 1288.93 <br />18 217.72 1688.90 <br />20 239.18 2133.28 <br />Elev. Area Capacity <br />(ft) (Acres) (Ac-Ft) <br />22 261.91 2621.22 <br />24 283.27 3149.92 <br />26 302.05 3725.66 <br />28 320.43 4337.70 <br />30 338.54 4984.05 <br />32 355.33 5666.66 <br />34 369.59 6383.04 <br />36 384.68 7128.01 <br />Source: Boulder Larimer Ditch Company. <br />Note: Dead storage of 0 ac-ft. <br />Enlargement History: Ish Reservoir was enlarged (approximately 4,800 ac-ft) in the early- <br />1900s. <br />Reservoir Storage Measurement: There is no measurement device on the Ish Reservoir inlet <br />ditch. Storage levels in Ish Reservoir are measured using a staff gage located along the <br />western end of the dam. Staff gage measurements are read bi-weekly, or more frequently <br />by the ditch rider, Irvin Adler, and reported to the District 4 Water Commissioner on a <br />monthly basis. Diversion measurements are calculated from the reservoir gauge height <br />based on change in storage contents. <br />Boulder Larimer Ditch Memorandum.doc 6 of 11 October 28, 2004 <br />