Built from 1865 to 1869 and extending six and one-half miles, the Amana Millrace supplied waterpower to the community's mills in Middle Amana and Amana. At Amana, it powered the woolen mill, calico factory, flour mill, and sawmill, with water-driven turbines turning gears and line shafts that transferred power to factory machinery, while steam engines supplemented the water power. In the 1920s, some of the line shaft system was replaced with electric generators and motors. The present hydroelectric plant was built in 1954 with a capacity of about 150 kilowatts, enough to power about 25 homes. Flooding of the Iowa River in 1993 severely damaged the millrace levees and made electricity generation impossible, but continuing preservation and maintenance efforts led by the Amana Colonies Historical Sites Foundation, with help from grants from the Save America's Treasurers program and the State Historical Society of Iowa, repaired the levees, and the hydro facility again produces clean, renewable power sold to the local electric company.