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Dillon Reservoir, sometimes referred to as Lake Dillon, is a large fresh water reservoir located in Summit County, Colorado, south of I-70 and bordered by the towns of Frisco, Silverthorne, and Dillon. It is a reservoir for the city of Denver, and its waters are under the control of Denver Water. Popular ski areas are close to the reservoir, including Copper Mountain, Keystone, Arapahoe Basin, and Breckenridge. ==History== In 1859, a large party of gold-seekers led by Ruben Spalding discovered gold near the headwaters of the Blue River,〔(The Lost Tenderfoot Mine )〕 which prompted a population surge in Summit County, Colorado. By October 1859, nearly 100 miners had camped along the river.〔 By 1880, the human population of Summit county had swelled to 5,459.〔https://dola.colorado.gov/demog_webapps/hcp_parameters.jsf〕 In 1881, Dillon Mining Company patented a 320-acre parcel and divided it into lots to establish the trade-post town of Dillon along the northeast bank of the Snake River, which is part of what was then called Blue River Valley.〔http://www.townofdillon.com/Modules/ShowDocument.aspx?documentid=474〕 The town of Dillon was incorporated in 1883,〔 but soon relocated to the west bank of the Blue River when Denver and Rio Grand Railroad came to Blue River Valley but had bypassed Dillon.〔 Dillon was moved a second time in 1892 when the Denver, South Park and Pacific Railroad arrived from the northeast. The town was located at the confluence of three rivers: the Blue, the Ten Mile and the Snake to provide one station for the two railroad lines.〔 In 1890, Dillon's population was 133, less than 20% as large as Breckenridge at the time.〔 Prior to its third move to the present location in 1961, the town had grown to 814 residents, the largest town in Summit County, however, most of this population consisted of construction workers for the dam.〔 The idea to dam the Blue River and divert the water to Denver originated in the early 1900s. Denver Water Board acquired most of the land needed for the reservoir for the price of back taxes during the Great Depression when many Dillon residents were unable to pay property taxes. By then, Denver Water Board had already acquired most of the water rights in the valley. In 1956, Denver Water Board notified the remaining residents and business owners they must sell and leave by September 15, 1961.〔 Dam construction began in 1961 and was completed in 1963. The dam is earth-filled, 5,888 feet (1795m) long, and rises 231 feet (70m) above the Blue River stream bed. The dam was completed in 1963.〔(Dillon Reservoir | Denver Water )〕 The dam diverts water from the Blue River Basin through the 23.3 mile (37.5 km) Harold D. Roberts Tunnel under the Continental Divide into the South Platte River Basin. Tunneling began in 1942 and the tunnel was holed-through in early 1960, with construction completed 1962. Curiously, alternative routes were still under consideration as late as the mid 1950s. Tunneling began from the east portal, just west of Grant on the North Fork South Platte River, but was eventually done from both ends as well as from a 916-foot (279m) deep access shaft 1.7 miles (2.7 km) northwest of Montezuma. At its deepest, the tunnel passes 4,465 feet (1361m) below the surface near Santa Fe Peak on the continental divide.〔Harold D. Roberts Tunnel, (of the South Platte Collection System ), Denver Water; accessed Aug. 2015.〕〔Bob Berwin, (Colorado: Roberts Tunnel turns 50 this year ), Summit County Citizen's Voice, Sept. 2, 2012; accessed Aug. 2012.〕〔Ernest E. Wahlstrom, (History of Geologic Investigations, Engineering Design, and Construction Methods of the Harold D. Roberts Tunnel, Colorado ), Geological Survey Professional Paper 831-A, Government Printing Office, 1974.〕〔R.L. Balmer, (Sinking a Large-Diameter, Concrete-Lined Access Shaft: Harold D. Roberts Tunnel, Colorado ), Information Circular 8029, Bureau of Mines, U.S. Dept. of the Interior, 1961.〕 The tunnel is fully lined, with an inside diameter of 10.25 feet (3.1m), and it permits a flow of 1020 cubic feet per second (29m3/sec). In a typical year, about 60,000 acre-feet (74 million m3) of water pass through the tunnel.〔John N. Winchester, (A Historical View: Transmountain Development in Colorado ), 2000; retrieved July, 2015.〕 The Denver Water Board set aside a 172-acre site for a new Town of Dillon. The Water Board had acquired a portion of the Fred Phillips Ranch at the northeast edge of what was to be Dillon Reservoir.〔 Residents and businesses were responsible for the expense of moving their structures. Many chose not to, but the Dillon Community Church, Town Hall, and Arapaho Café and Motel were moved to the new town, and they still exist today. The original church building is now a museum operated by the local Historical Society with many Dillon artifacts of the late 1800s and early 1900s. Also, 327 graves were moved to a new 39-acre cemetery northeast of the new town site.〔 Several buildings ended up in neighboring towns. Antler’s Café and Bar and the Kremmling Store were moved to Frisco. The Hamilton–Dillon Hotel was moved to Breckenridge. The Mint Bar, Old Dillon Inn, Wildwood Bar, the post office and a general store were moved to what later became Silverthorne. Most of the rest of Old Dillon’s homes and buildings were demolished. Once cleared, the valley was ready for the reservoir, which was completed in 1963.〔 After its third move, Dillon’s population shrank to 57 people, smaller than Breckenridge, Silverthorne, or Frisco. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dillon Reservoir」の詳細全文を読む スポンサード リンク
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