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
Hoover Dam Police Security Zone encompasses around Hoover Dam and Lake Mead; before the opening of the bypass, this included of U.S. Highway 93 (US 93). Vehicles had to pass through inspection checkpoints, located on US 93 north of the dam in Nevada, and south of the dam in Arizona, before crossing. With the opening of the bypass, traffic patterns changed dramatically. Through traffic no longer goes through a checkpoint on either side of the river. On the Nevada side, the dam road now branches off US 93 before the checkpoint, which remains in operation to screen dam visitors. On the Arizona side,