MADISON, Wis. – The Wisconsin Department of Natural Resources (DNR) today announced the presence of elevated levels of per- and polyfluoroalkyl substances (PFAS) in surface water samples taken from Madison-area lakes and along the Yahara River.
The DNR found elevated levels of PFAS in Lake Monona and Starkweather Creek in 2019, which resulted in a new PFAS fish consumption advisory for those two water bodies. The DNR collected surface water and fish samples in 2019 due to PFAS-containing stormwater leaving the Dane County airport into Starkweather Creek and Lake Monona.
Due to public safety concerns, the DNR collected additional surface water samples in 2020 on lakes Mendota, Monona, Upper Mud, Waubesa and Kegonsa, as well as along sections of the Yahara River between the lakes.
The DNR also collected samples from Lake Wingra and Nine Springs Creek. PFAS compounds were discovered throughout the areas sampled, many of those samples were at levels above what the DNR may consider acceptable.
PFAS are a group of human-made chemicals used for decades in numerous products, including non-stick cookware, fast food wrappers and stain-resistant sprays. These legacy contaminants have made their way into the environment in a variety of ways, including spills of PFAS-containing materials, discharges of PFAS-containing wastewater to treatment plants and certain types of firefighting foams.
PFAS do not break down in the environment and have been discovered at concentrations of concern in groundwater, surface water and drinking water. PFAS are known to bioaccumulate in the tissues of fish and wildlife. They also accumulate in the human body and pose several risks to human health.
Surface Water Sampling
Lake Mendota was found to have values below 1.0 parts-per-trillion (ppt) for the PFAS compounds PFOS and PFOA. However, Lake Monona had values as high as 9.2 ppt PFOS and 2.4 ppt PFOA. Values for Upper Mud were 8.7 ppt PFOS and 2.3 ppt PFOA. Waubesa had levels of 7.8 ppt PFOS and 2.4 ppt PFOA, and Kegonsa 6.2 PFOS and 2.3 ppt PFOA.
Samples taken in 2020 were analyzed for 36 PFAS compounds, including PFOS and PFOA, at the Wisconsin State Lab of Hygiene.
“The sample results indicate that PFAS compounds are present in all of the Madison area lakes. Concentrations of PFAS compounds in Lake Mendota and Lake Wingra, located upstream of Lake Monona, have lower concentrations than Lake Monona and the subsequent downstream lakes and sections of the Yahara River,” said Adrian Stocks, DNR Water Quality Program Director. “Additionally, concentrations in Lake Monona of one particular PFAS compound, PFOS, were very similar to results from DNR sampling efforts of the lake in 2019.”
The 2019 samples showed 10 ppt to 12 ppt for PFOS and less than 3 ppt for PFOA. The DNR’s 2019 sampling of Starkweather Creek began following results of sampling completed at the Dane County Airport that showed elevated levels of PFAS. The stormwater system at the airport discharges to Starkweather Creek which ultimately enters Lake Monona near Olbrich Park. PFAS contamination was found in Starkweather Creek from its headwaters northeast and east of the airport, through its length to where it discharges into Lake Monona. PFOS concentrations ranged from less than 1 ppt to 3700 ppt.
There are known discharges of PFAS compounds to soil, surface water and groundwater on the airport property likely stemming from multiple responsible parties. The DNR has regulatory oversight in cases where there has been a discharge of a hazardous substance to the environment. The DNR is actively working with responsible parties to discuss next steps.
2020 Fish Tissue Sampling
The DNR continues to conduct comprehensive fish contaminant monitoring on the Yahara chain of lakes, targeting a variety of species for PFAS and other contaminants. Due to the time required to process and analyze fish tissue samples, the DNR expects the results of this testing are expected in Spring 2021.
More information on how the DNR is addressing PFAS contamination in Wisconsin is available here.