Blue Mountain Lake is a reservoir in Arkansas, United States. A U.S. Army Corps of Engineers Lake on the Petit Jean River in west central Arkansas, Blue Mountain Lake has approximately 50 miles of shoreline, located between Mount Magazine and the Ouachita Mountains just west of Havana, Arkansas. The lake offers fishing, boating, swimming and camping; it is also the focal point of the view from the lodge atop Mount Magazine, home of Mount Magazine State Park.