Rend Lake is a 13-mile-long (21 km), 3-mile wide (4.8 km) reservoir located in Southern Illinois in Franklin and Jefferson Counties near the town of Benton. It covers 18,900 acres (76 km2), stores 185,000 acre-feet (228,000,000 m3) of water, and supplies over 15 million U.S. gallons (57 Ml) of water per day to 300,000 persons in over 60 communities. The reservoir is up to 35 feet (10.7 m) deep, but its average depth is closer to 9.7 feet (3.0 m). Its elevation is 405 feet (123.4 m) above sea level.