The Muskingum River sub-basin is the largest single drainage system in Ohio. At 8,095 square miles, the Muskingum drainage extends from Marietta, Ohio on the Ohio River northward to within 25 miles of the shoreline of Lake Erie. The sub-basin encompasses 5 counties and portions of 22 others. A number of cities and urban areas dot this landscape surrounded by cultivated and forested land covers. The northern and western portions of the region were glaciated featuring rolling hills, deep soils and broad valleys while the southern and eastern sections were spared the advances of glaciers and feature more rugged terrain. The estimated population of this hydrologic region is 1.5 million with projections of 22 percent growth by 2050.
Due to damaging floods in the 1930s, a system of reservoirs was authorized for construction by USACE. Today there are 14 reservoirs operating in the region thanks to that original authorization. An additional two reservoirs were authorized later and now Dillon (1959) and North Branch Kokosing River (1972) lakes are operated by USACE for flood control purposes as well. Four of the original reservoirs are single-purpose reservoirs for flood control and have no permanent conservation pool ("dry-dams"). Average annual flood damages prevented by this system are estimated at $90.0 million. The original 14 reservoirs were developed in close cooperation with the Muskingum Watershed Conservancy District and the lands acquired for the projects are now operated exclusively by the MWCD for recreation and other purposes; the dams are operated by USACE. Several of the 16 reservoirs provide water supplies for surrounding counties and municipal areas and extensive day-use and overnight recreation facilities including lodging facilities and golf courses are operated by the MWCD. All of the counties and approximately 140 municipal jurisdictions participate in the national flood insurance program (NFIP).