During World War II, the part of the Refuge that is now an NPL site (about 20,000 acres of the 43,000-acre Refuge) was used by the War Department as an ordnance manufacturing plant. The Illinois Ordnance Plant (lOP) employed thousands of people during the war years. After the war, the land was transferred to the Department of Interior (DOI).

The Refuge was established by Congress in 1947 with a mission to support wildlife, recreation, agriculture, and industry. Under this mission, DOl leased the former lOP buildings for a variety of industrial uses, including manufacturing of ordnance, explosives, transformers, ink, and metal-plated parts. Prior to modern environmental laws, it was common practice for industrial facilities, including those on the Refuge, to use unlined landfills and dumps to dispose of the waste generated by their operations. As a result, a number of locations within the closed portion of the Refuge became contaminated.