The Spearfish Hydro system was purchased by the City of Spearfish in 2004 from Homestake Mining Company to maintain water flow through the city and downstream users.
The diversion tunnel from the Maurice intake to Forbay totals 5 miles in length. Mining was completed in one year with 14 headings working towards each other without any errors in elevations or horizontal mismatch. It is constructed of five-foot high concrete side walls and a poured floor. The roof consists of either poured concrete, arched concrete blocks, or nature arched rock.
The Stand Pipes are located on a ridge south of Spearfish, above the mouth of Spearfish Canyon. The Stand Pipes reduce the water shock within the pipelines feeding the plant, as the water flows change, the height of the Stand Pipes change.