Lake Rabun is a 835-acre reservoir with 25 miles of shoreline located in the Northeastern corner of the 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 section of the Tallulah River. Coordinates 34°45′55″N 083°24′57″W
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.
Lake Rabun's Mathis Dam was completed in May 1915, but the lake was not filled for ten years waiting for the completion of a tunnel from near the dam to the power generator at Tallulah Falls. It then created a reservoir of over ten million gallons covering 834 acres with a normal water level of 1,690 feet 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 and a span of 660 feet . 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.