Lake Oahe Pierre, South Dakota and extends nearly as far north as Bismarck, North Dakota. Mobridge, South Dakota is located on the eastern shore of the central portion of the lake. Bridges over Lake Oahe include US Route 212 west of Gettysburg, South Dakota and US Route 12 at Mobridge. The former town of Forest City has been flooded beneath Lake Oahe, about 9 miles west of Gettysburg. Prehistoric archaeological sites have been explored in the area, including Molstad Village near Mobridge. It dates to before the emergence of the Arikara, Hidatsa and Mandan as separate peoples, and has been designated as
Lake Oahe Rock Indian Reservation brought a petition to the U.S. Army Corps of Engineers (USACE) and sued for an injunction to stop the project. On December 4, 2016 USACE denied the easement that "would allow the Dakota Access Pipeline to cross under Lake Oahe" and Jo-Ellen Darcy, the United States Assistant Secretary of the Army "said she based her decision on a need to explore alternate routes for the Dakota Access Pipeline crossing." Darcy said "that the consideration of alternative routes would be best accomplished through an Environmental Impact Statement with full public input and analysis." President Trump soon thereafter issued