Garrison

U.S. Army Corps of EngineersMercer CountySPP

Garrison Dam is a federally owned conventional hydroelectric plant on the Missouri River near Riverdale in Mercer County, North Dakota, impounding Lake Sakakawea. The powerhouse holds five generating units brought online between 1956 and 1960, totaling 583.4 MW of nameplate capacity (510 MW net summer), and is built and run by the U.S. Army Corps of Engineers' Omaha District. All five units remain in service, with no whole-plant or unit retirements scheduled. Hydropower here is a byproduct of the dam's primary flood-control, navigation, irrigation and water-supply mission on the upper Missouri River mainstem system.