MADISON, Wis. (AP) — Marshfield and Adams have joined the list of Wisconsin cities that have shut down municipal wells due to PFAS contamination.

Wisconsin Public Radio reported that the state Department of Natural Resources announced Thursday that sampling in the two cities has detected PFAS levels exceeding 20 parts per trillion, a health standard recommended by the state Department of Health Services.

Marshfield shut down 15 wells after receiving results Tuesday. Adams shut down one of two wells with elevated PFAS levels after receiving results May 4.

Communities including La Crosse, Eau Claire and Madison have also shut down wells due to PFAS contamination. The DNR is investigating PFAS contamination at nearly 100 sites across the state.

The DNR’s policy board approved surface and drinking water standards for PFAS in February but failed to set groundwater standards. The surface and drinking water standards are still subject to legislative approval. The Legislature’s rules committee has requested a meeting with DNR officials to discuss the standards. That meeting could take place as early as next month.

PFAS is an acronym for perfluoroalkyl and polyfluoroalkyl chemicals that don’t break down in nature. The chemicals are found in fire-fighting foam and a wide range of everyday products such as cookware and clothing.