Mosquito Lake State Park in Trumbull County is a 6,601.13-acre Ohio park centered on the southern half of Mosquito Creek Lake. Its landscape emerged from a flood-control project planned in the 1930s, authorized by the Flood Control Act of 1938, and completed with the dam in April 1944 by the United States Army Corps of Engineers. The project also aimed to regulate streamflow, reduce pollution linked to local steel processing, and supply water to Warren. Most of the lake and surrounding land are federally owned and leased to the Ohio Department of Natural Resources. Today the park combines that water-management legacy with camping, hiking, boating, and fishing.