After three years of operation, the showcase Foothills water treatment plant, serving the base needs of the Denver, Colorado, metropolitan area, has been performing at, or above expectations. Taking hydraulic advantage of its location above the city, the plant's pumping costs are minimal and the plant's hydro turbine generates enough power to operate the facilities and sell excess electricity. A minimum staff can operate the automatically controlled processes. The design enables operators to choose the total treatment process or bypass coagulation, flocculation and sedimentation to minimize operation and maintenance costs, depending on seasonal water quality. Solids drying beds take advantage of the climate, further lowering treatment costs, which in 1986 averaged only about $0.03 per thousand gallons. Includes tables, figures.