Oahe Dam dam upstream is Garrison Dam, near Riverdale, North Dakota, and the next dam downstream is Big Bend Dam, near Fort Thompson, South Dakota. In September and October 1804, the Lewis and Clark Expedition passed through what is now Lake Oahe while exploring the Missouri River. Oahe Dam was authorized by the Flood Control Act of 1944, and construction by the United States Army Corps of Engineers began in 1948. The world’s first rock tunnel boring machine (TBM) was invented in 1952 by James S. Robbins for the Oahe Dam project, which marked the beginning of machines replacing human tunnelers. The
Big Bend Dam 47 crosses over the dam, connecting Lyman and Buffalo Counties. Big Bend Dam is located approximately north of I-90, and approximately southeast of Pierre. The next dam upstream is Oahe Dam, near Pierre, and the next dam downstream is Fort Randall Dam, near Pickstown. The construction of the dam resulted in the dislocation of people on the Crow Creek and Lower Brule Reservations. The flooding of the land for the reservoir also resulted in the loss of limited plant life resources used by these people for food and medicine. A monument at Big Bend Dam dedicated in 2002, the Spirit