Summersville Lake, located on the Gauley River in Nicholas County, is West Virginia's largest lake, with 2,790 surface acres at summer pool stage and 60 miles of shoreline. The dam was built between 1960 and 1966 by the U.S. Army Corps of Engineers at a cost of nearly $48 million. President Lyndon B. Johnson came on September 3, 1966, to dedicate the dam and lake.

A story is told as to the naming of the project. The Corps of Engineers normally names its dams for the nearest community, which in this case was Gad, a village near the present site of the Long Point Marina. But after brief consideration of "Gad Dam," the name Summersville was chosen instead.

Summersville Dam controls a drainage area of 803 square miles, including parts of Randolph, Nicholas, Webster, Pocahontas, and Greenbrier counties. The rock-fill dam is the second-largest of its type in the eastern United States and required 12 million cubic yards of earth and rock. The dam is 390 feet high and 2,280 feet long. Water is released downstream through a 1,555-foot long, 29-foot diameter tunnel, creating a spectacular sight from the highway that crosses the dam. Water releases during the fall lake draw-down have spawned a multimillion dollar whitewater industry on the Gauley River downstream.

With its large summer size and scenic sandstone cliffs, Summersville Lake is popular with boaters, fishermen, and other visitors. Prime recreational features include Battle Run Campground on the lake shoreline, a picnic area, Long Point overlook, Salmon Run and Long Point boat ramps, and Summersville Lake Marina. Rock climbers have established more than 50 routes around the Hughes Bridge (U.S. 19) area, and diving and hiking are also popular.

The total amount of government land at Summersville Lake is 9,346 acres, of which 5,390 acres are leased to the state for fish and wildlife management. Construction of a hydropower project at Summersville Dam began in 1999, and was completed and operating in June 2001. The two-unit powerhouse generates 217 million kilowatt-hours of electricity per year, enough for 50,000 homes.