Lake Rabun is the third lake out of six managed by the Georgia Power Company. Mathis Dam was completed in 1915, but the lake was not actually impounded until almost ten years late . This delay was due to construction of a mile long tunnel dug between the lake and the power generator at Tallulah Falls. By 1925 the lake became a haven for many residents of Atlanta, who would make the day long trip by car to enjoy the area. Lake Rabun at an elevation of 1689 feet , with a surface area of 835 acres and 25 miles of , is the second largest lake in the six lake chain. While not as large as Lake Burton, Rabun offers water skiing, fishing, and wonderful afternoon cruises.

Lake Rabun began filling in May 1915 with the completion of the Mathis Dam to form a reservoir of over ten million gallons covering 834 acres (3.4 km2) with a normal water level of 1,690 feet (515 m) above mean sea level. The property was purchased by the Georgia Railway and Power Company (later renamed Georgia Power Company). The Mathis Dam is an ambursen-type concrete dam with a height of 108 feet (33 m) and a span of 660 feet (201 m). The Terrora Hydroelectric Plant at Mathis Dam has a generation capacity of 16,000 kilowatts. The reservoir elevation is listed as 1,683 feet on topographic maps, but Georgia Power considers the lake full at an elevation of 1,689.6 feet.

Lake Rabun is a twisty 835-acre (3.4 km2) reservoir with 25 miles (40 km) of shoreline located in the Northeastern corner of Georgia in Rabun County. It is the third lake in a six-lake series that follows the original course of the Tallulah River. The series begins with Lake Burton as the northernmost lake, followed by Lake Seed, Lake Rabun, Lake Tallulah Falls, Lake Tugalo, and Lake Yonah. Lake Rabun was built in a deep valley located along a 10-mile (16 km) section of the Tallulah River.

The lakes are owned and operated by the Georgia Power Company to generate hydroelectric energy for Georgia's largest city, Atlanta. At one time these lakes were the largest producers of electricity in the state of Georgia. Now, they only provide peak power supply.