[1] The Krejci family owned a parcel exceeding 234 acres (95 ha) and opened a junkyard for burning trash and dumping scrap metal in 1940.

The Krejcis vacated the property, and the following year, a person collecting bottles on the site became ill. Park rangers would complain of headaches, rashes, and odors.

[3] Ford Motor Co, General Motors, Federal Metal Co, Minnesota Mining and Manufacturing (3M), Chrysler, Kewanee Industries (a subsidiary of Chevron Corporation USA), and Waste Management of Ohio were found to be potentially responsible parties (PRPs) in contributing and transporting toxic waste to the Krejci dump.

All of these companies were sued in 1997 by the US government through CERCLA (Superfund) to recoup the cost of the cleanup, and all of the PRPs agreed to settle out of court with the exception of 3M, who went to trial and lost.

At one point in the cleanup, thousands of multicolored flags covered the former dump's property, identifying multi-increment sub-sample locations.

But it wasn't until August 2012 that the NPS declared "comprehensive post-excavation soil sampling effort establishes that remediation goals for the 46-acre former dump site have been met," and, "The final steps necessary to restore the Site may now begin, including final grading; re-vegetation using native meadow grasses, forbs and shrubs; and restoration of 3 acres of wetland and wet meadow habitats.

"Upon completion of the cleanup, the site will be restored to natural conditions consistent with surrounding Park habitat, and restrictions on public access will be removed.