Rend Lake is a 13 miles (20.9 km)-long, 3 miles (4.8 km)-wide southern Illinois reservoir in Franklin and Jefferson Counties near Benton, Illinois. The lake contains 18,900 acres (76 km²) of water, stores 185,000 acre feet (228,000,000 m3) of water, and supplies over 15 million gallons 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. In 2010, Rend Lake was designated as an Important Bird Area of Illinois.