PFAS and PFOS advisories issued for fish in Castle Rock Lake, Lake Mohawksin

State environmental and health officials have announced a new consumption advisory for several fish species in Castle Rock Lake and Lake Mohawksin because of potential contamination from PFAS and related chemicals.

Both lakes are segments of the Wisconsin River. Elevated levels of PFOS (perfluorooctane sulfonate) and PFAS (per- and polyfluoroalkyl substances) were detected in several species in April 2021 and continue to be present a danger, according to the announcement Tuesday from the Department of Natural Resources (DNR) and the Department of Health Services (DHS).

PFOS and PFAS are part of a larger group of man-made chemicals. They were used in many forms of products, from firefighting foam to nonstick coatings on food wrappers and pans. Dubbed “forever chemicals,” the compounds don’t break down in the environment or within the  body. PFAS and PFOS have been linked to a myriad of chronic health issues, including thyroid disorders and multiple forms of cancer. Humans, wildlife, pets and livestock are all affected by PFAS and PFOS-contaminated water and soil.

For Castle Rock Lake, the advisory specifies that bluegill, yellow perch, black crappie and common carp should all be consumed in small quantities. For all of the fish besides the carp, the DNR and DHS advise that people only eat one meal per week. The common carp, however, has a much more stringent advisory of just one meal each month.

Bluegill, yellow perch and black crappie are also on the list for Lake Mohawksin, along with rock bass and pumpkinseed. Rock bass, pumpkinseed and black crappie caught in Lake Mohawksin should be consumed no more than once a month, the agencies said.