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.
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 diverts water from the Blue River Basin through the Harold D. Roberts Tunnel under the Continental Divide into the South Platte River Basin. Dillon Dam is earth-filled, 5,888 feet long, and rises 231 feet above the Blue River stream bed. The remains of the ghost town under the reservoir is a spectacle for divers who want to see Dillon's past.