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.