Garrison Dam is a large earth-fill dam located on the Missouri River in North Dakota. Completed in 1956, it was built primarily for flood control, irrigation, and hydroelectric power generation. The dam creates the Lake Sakakawea, one of the largest reservoirs in the United States, which provides recreational opportunities and supports local wildlife. The dam is operated by the U.S. Army Corps of Engineers and plays a crucial role in managing water flow in the region. It helps to prevent flooding downstream and provides water for agricultural use, benefiting the local economy and communities surrounding the reservoir.