Authorized by the Flood Control Act of 1938, Mosquito Creek Lake is one of 16 flood control projects in the Pittsburgh District. The project provides flood protection for the Mahoning River Valley as well as the Beaver and upper Ohio Rivers.
Since its completion in 1944, Mosquito Creek Lake has prevented flood damages estimated to be in excess of $418 million. Mosquito has the capability to store the equivalent run-off of 29 inches of precipitation from its 97 square mile drainage area. When compared to the saving which have resulted, the construction cost of just over $4 million appears small.
Mosquito Creek Lake also stores water and releases it downstream during dry periods to improve water quality and quantity for domestic and industrial use, recreation, aesthetics and aquatic life.
A feature unique to Mosquito Creek Lake is its use of an uncontrolled natural spillway. The natural spillway is located at the upper end of the lake in a low-lying reach of the Mosquito Creek – Grand River Divide. The elevation of the spillway at the point of divide is such that if an impoundment of flood waters should fill the lake, to an elevation of 904 feet above sea level, the southerly outflow of the lake would be reversed. The outflow would then be discharged through the natural spillway into a tributary of the Grand River which flows north into Lake Erie.