East Fork Lake, reservoir, Richland co., SE Ill., on E. Fork Fox R., 2 mi/3.2 km NNE of Olney; 3 mi/4.8 km; 38°45'N 88°06'W. Max. capacity of 27,600 acre-ft. Formed by East Fork Dam (55 ft/17 m high), built (1971) for water supply purposes for Olney.