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
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