MADISON, Wis. – Based on fish tissue data, the Wisconsin Department of Natural Resources (DNR) and the Department of Health Services (DHS) are recommending PFAS-based fish consumption advisories for Starkweather Creek and Lake Monona in Dane County.
Recent sampling by the Wisconsin Department of Natural Resources shows elevated PFOS in fish tissue and surface water in those waterways. PFOS is one of many per- and polyfluoroalkyl substances (PFAS). PFOS detection is the driving force behind establishing the fish consumption advisory for Starkweather Creek and Lake Monona in Dane County.
PFAS are a group of human-made chemicals used for decades in numerous products, including non-stick cookware, fast food wrappers, stain-resistant sprays and certain types of firefighting foam. 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.
The risk of health problems increases with the amount of contaminated fish you eat. Following these advisories will help protect you from excess PFOS exposure and other contaminants found in fish, including mercury and PCBs. The advisories could change in the future as the DNR and DHS continue to learn more about the health risks from eating fish caught from this area and more fish data become available.
As part of the DNR’s PFAS efforts to monitor fish tissue and water chemistry at select sites around the state, surface water samples were collected at four locations in the east and west branches of Starkweather Creek over the summer of 2019, along with fish near the mouth of the creek where it enters Lake Monona. PFAS was detected in samples from all four locations.
In October, additional surface water sampling was conducted at the four original sampling locations as well as 11 new locations in Starkweather Creek and five locations in Lake Monona. The purpose of the sampling was to gain a better understanding of the distribution and concentrations of PFAS in Starkweather Creek.
Fish tissue samples were collected from Starkweather Creek and Lake Monona. A map showing all water sample locations and sampling results are located on the DNR’s PFAS webpage.
Fish Tissue Results
PFOS was detected in all fish sampled from Lake Monona and Starkweather Creek. The revised consumption guidelines for fish from Starkweather Creek and Lake Monona are listed below. For all species not mentioned in the table, please refer to the general Safe Eating Guidelines or refer to the Department of Health Services, “Choosing Which Fish to Eat” guidelines.
Fish consumption guidelines for Lake Monona and Starkweather Creek have been amended to reflect these changes. The DNR and DHS provide information about the number of meals and species of fish the public can safely eat. By following the recommendations, the public can reduce their exposure to pollutants.
Surface Water Results
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. Concentrations were lowest northeast and east of the airport and in the East Branch of Starkweather Creek. The highest concentration was found in a stream on the southeast side of the airport.
PFAS concentrations were generally stable in the creek from Anderson Road until the West Branch mixes with the lower PFAS concentrations in the East Branch south of Milwaukee Street. That mixing appears to lower the PFAS concentrations in the creek until it enters Lake Monona.
Concentrations in Lake Monona were 10 ppt to 12 ppt for PFOS and less than 3 ppt for PFOA. These concentrations were less than the concentrations found in Starkweather Creek between Anderson Road and Lake Monona.
Starkweather Creek and Lake Monona are not sources of water for the Madison Water Utility. The DNR is currently working with DHS on developing groundwater, drinking water and surface water standards for PFAS.