PFAS Contamination Just Found at 3M Wausau Greystone is 800 Times Higher Than DHS-Proposed Limit

map of 3m greystone groundwater sampling locations

PFAS Contamination Just Found at 3M Wausau Greystone is 800 Times Higher Than DHS-Proposed Limit

3M Company, PFAS
March 15, 2026

According to records recently uploaded to the DNR’s BRRTS database for 3M Company’s Wausau Greystone Quarry, PFAS groundwater contamination on the site was identified at a level as much as 800 times higher than the groundwater enforcement standards proposed by Wisconsin’s Department of Health Services (DHS) in 2025.

In February 2025, DHS proposed a limit for PFOA in Wisconsin groundwater of 4 ng/l. According to the testing results submitted to the DNR, the PFOA level found in a September 2025 groundwater sample from 3M’s Wausau Greystone site was 3,200 ng/l — 800 times higher. That level was found at MW-15.

In the same set of DHS-proposed groundwater standards, the PFOS limit is also listed as 4 ng/l. As reported in the table of testing results, PFOS groundwater levels identified in 3M’s Greystone samples from September were as high as 2,100 ng/l — 525 higher. This concentration was identified at MW-4D.

Additionally, extremely high levels of another PFAS — NEtFOSAA — were found in the groundwater of this 3M property, at a concentration of 9,700 ng/l. This testing result is from MW-4.

While, apparently, no proposed groundwater standard for NEtFOSAA exists in the limits put forth by DHS in 2025, the department provided past information to the public stating that “NEtFOSAA is one of several PFAS that can turn into perfluorooctane sulfonate (PFOS) in the body and environment” and that “[s]tudies among people and research animals have shown that high levels of PFOS may affect reproduction, development, cholesterol levels, liver and thyroid function, and immune response.” Therefore, DHS recommended a groundwater standard for NEtFOSAA of 20 ng/l at the time. The level of NEtFOSAA just identified in the groundwater of the 3M Greystone site at MW-4 is 485 times higher than the proposed limit in these past DHS materials.

The recent Groundwater and Surface Water Analytical Results from 3M Greystone are embedded below, along with soil sampling results.

The 2025 proposed groundwater standards from DHS can be found online, or reviewed in the screenshot below which summarizes them. The screenshot is taken from a DHS letter that was sent to the DNR.