Lake Oahe Lake Oahe Lake Oahe (oh-WAH'-hee) is a large reservoir behind Oahe Dam on the Missouri River; it begins in central South Dakota and continues north into North Dakota in the United States. The lake has an area of and a maximum depth of . By volume, it is the fourth-largest reservoir in the US. Lake Oahe has a length of approximately and has a shoreline of . 51 recreation areas are located along Lake Oahe, and 1.5 million people visit the reservoir every year. The lake is named for the 1874 Oahe Indian Mission. Lake Oahe begins just north of
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