Crab Orchard Lake is approximately 6,965 acres with a maximum depth of about 30 feet. The average depth is about 7 feet. The Lake is an impoundment of Crab Orchard Creek. Secondary tributaries include Wolf, Sugar, Pigeon and Grassy creeks. All inlets are intermittent. Normal lake elevation is 405 feet above mean sea level. Annual fluctuation, typically, ranges from 1 to 2 feet above to 1 foot below that level. In extreme years, the lake can rise as much as 4 to 5 feet or drop 2 to 3 feet below. Surface elevation is controlled by a fixed-sill concrete spillway.