Per- and polyfluoroalkyl substances (PFAS) have been found in the Yahara River and all five of Madison, Wisconsin’s lakes.
State officials have not warned against eating the fish until they confirm they are contaminated, however, reported the Wisconsin State Journal.
The lakes are not sources of drinking water but the primary concern is how PFAS are accumulating in fish, according to Adrian Stocks, water quality program director for the Department of Natural Resources.
The DNR has collected fish from the Yahara lakes for testing and the results should be available sometime in the winter or spring of 2021.
The Department of Health Services (DHS) recommends eating carp, largemouth bass, walleye and perch from that lake no more than once a month and that it is safe to eat bluegill once a week.
After finding PFAS in fish from Lake Monona, the DNR collected additional water samples last year from lakes Mendota, Monona, Upper Mud, Waubesa and Kegonsa, and sections of the Yahara River between the lakes.
The DNR tested for 36 PFAS compounds and found the highest concentrations were found in Lake Monona and the lakes downstream. The lowest concentrations were found in Lake Wingra and Lake Mendota, reported the Wisconsin State Journal.
The data suggest most PFAS are coming from Madison, where the DNR has ordered the city, county and National Guard to clean up former firefighter training areas around the Dane County Regional Airport and Truax Field.
Lake Mendota was found to have values below 1.0 parts per trillion for two compounds, PFOS and PFOA. Concentrations of PFOS ranged from 9.23 ppt on Lake Monona to 1.12 ppt on Lake Wingra.
Michigan has set PFOS surface water standards of 11 to 12 ppt for PFOS.
Earlier this month, the DNR issued a PFAS consumption warning for smelt from Lake Superior. There are also PFAS consumption advisories for Lake Monona and pools 3 through 6 of the Mississippi River.
