The National Park Service acquired the Krejci Dump in 1985 to include as part of the recreation area. They requested a thorough analysis of the site's contents from the Environmental Protection Agency. After the survey identified extremely toxic materials, the area was closed in 1986 and designated a superfund site under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) of 1980. Litigation was filed against potentially responsible parties: Ford, GM, Chrysler, 3M, Waste Management, Chevron, Kewanee Industries, and Federal Metals. Only 3M would not agree to a settlement, and the company lost at trial. Removal of toxic materials began in 1987 with of contaminated soils and debris removed by 2012, and restoration completed by 2015.