Boone Lake is a reservoir in Sullivan and Washington counties in northeastern Tennessee, formed by the impoundment of the South Fork Holston River and Watauga River behind Boone Dam. Boone Reservoir’s 4,400 acres (1,800 ha) extend along the South Fork Holston River forming two river extensions. According to TVA, “at maximum pool level, one arm of the lake extends about 16 miles (26 km) up the South Fork Holston River, and the other extends approximately 15 miles (24 km) up the Watauga River".