After nearly three years of work by a variety of groups, Sheridan Lake and its dam were officially dedicated for use by the public on October 20, 1940. Approximately 5,000 people attended the dedication ceremony.
Like nearby Pactola Lake, Sheridan was also flooded to become a lake after the fall of mining in the area. Once known as “The Golden City,” Sheridan was established in 1875 alongside the rush for gold. Numerous miners resided in Sheridan, which boasted several saloons, storefronts and churches. Sheridan was even the county seat for Pennington County for three years from 1875-1878. However, mining in the town eventually subsided as prospectors moved their endeavors toward Deadwood and Lead. By 1920, there were only ten residents of Sheridan.
Construction on the Sheridan Dam began on August 15, 1938 and was completed on November 1, 1940. Congressmen Theodore B. Werner and Francis Case helped draw media attention to the project between 1936 and 1937. Much of the construction of the dam was completed by the Civilian Conservation Corps and the WOrks Progress Administration.
Sheridan Lake was constructed to cover approximately 380 acres with seven miles of shoreline and an average depth of 35 feet. The dam itself is 126 feet high and 850 feet wide.