New Jersey warned five manufacturers that they could be on the hook for millions to assess and clean up damage to natural resources from widespread contamination by fluorinated chemicals.

In a March 25 directive, the New Jersey Department of Environmental Protection ordered Solvay SA, DuPont Specialty Products USA LLC, DowDuPont Inc., Chemours Co., and 3M Co. to provide a detailed accounting of their use and discharge of the chemicals, which have been...