This view of the lower level of the Hydroelectric plant shows the massive pipes that channeled the river's flow to three electric generators. Water entered the plant through the flume at the back of the room and flowed through the large gate valves at each generator before leaving the hydroelectric plant, at the bottom right of the photograph.
The building in front of you is the former Sioux Falls Light & Power hydroelectric plant. More recently, it was called the Northern States Power, or NSP, building. The plant began generating electricity for Sioux Falls in 1908.
This hydroelectric plant replaced earlier power plants, which were unable to meet the city's increasing demand for electricity. In addition to providing electricity for street lights, the hydroelectric plant generated power for the city's streetcars.
Water for the plant was stored in the old Queen Bee Mill pond. The level of water in the pond was raised by building a longer, taller dam. This was necessary to provide the "head" or pressure necessary to run the hydroelectric plant's turbines.
Demand for electricity out grew the hydroelectric plant's ability to generate enough power using water. Five years after it was built, the plant was enlarged and a new source of energy - coal fired steam generators- became the main
source of electricity. The water powered generators were maintained as a back-up power source until the late 1940s.
The hydroelectric plant used the dam and headrace that were built for the Queen Bee Mill. Both the hydroelectric plant left) and the mill (right) are now listed on the National Register of Historic Places. Northern States Power donated the hydroelectric plant property to the city in 1974.
The surge tower served as a giant shock absorber, allowing the generators to be shut down in a moment's notice.
The flume carried water from the mill pond, through the surge tower, to the turbines.