Authorized by the Flood Control Acts of 1936 and 1938, Tionesta Lake is one of 16 flood-control projects in the Pittsburgh District. Tionesta is a key link in a system of flood-control projects for the Allegheny and upper Ohio Rivers. Since its completion in 1940, Tionesta has prevented more than $650 million in flood damage. The project’s flood control capabilities were dramatically demonstrated during the 1972 flooding resulting from Tropical Storm Agnes when over $62 million in damages were prevented by Tionesta alone.