riverside park wausau wisconsin dioxin contamination

DNR Requiring More Dioxin Testing in Riverside Park

On February 24, the WDNR notified the City of Wausau that additional soil sampling is required to fully define the extent of dioxin contamination in the neighborhood park

Years of Denial, Pushback, and Delay from City Officials and Departments Marked the History of Park Testing: “There’s nothing that says there are issues in Riverside Park”

Soil testing in the recent past confirmed multiple exceedances of state regulatory standards for dioxins and furans in the soil of Riverside Park. The testing that confirmed the exceedances came after years of sustained, intense requests from the community, especially from residents on the southwest side of Wausau. The City was ultimately forced by regulators to investigate and address dioxin contamination in the neighborhood after it received a Responsible Party letter from the WDNR.

Public records show that significant levels of dioxin and furan were detected the in the soil of the park from 2006 soil testing there, and that the City of Wausau was provided with the results of the testing in 2008, yet took no action to define the extent of the contamination and address it. Over the years, Wausau area residents who requested more testing in the park based on documented concerns were sometimes not only rebuffed, but treated with discourtesy and mockery from municipal government.

While, at times in the past, municipal government officials and staff denied any soil problems in the park, or at other sites like the former Connor Forest Industries property on Cleveland Avenue, calling citizens “rabble-rousers” or the concerns “much ado about nothing,” these types of claims from the city have since been thoroughly debunked, as more soil testing demonstrates that the position of there-is-no-issue and others like them are demonstrably false.  

Confirmation that Dioxin Contamination in Riverside Park Exceeds State Regulatory Standards

Results from the City of Wausau’s own September 2020 soil sampling in Riverside Park show that multiple sample locations demonstrated exceedances of state DNR regulatory standards for a non-industrial setting. The City’s environmental consultant, REI Engineering, performed the soil sampling and the analysis of the results which came from Pace Laboratories. REI’s analytical spreadsheet of the latest testing results was included in the packet for the December 7, 2020 Parks & Recreation Committee meeting and can be found via the following link:


From page 2 of the Parks & Recreation Committee meeting packet referenced above:

“When looking at only individual compounds, 19 samples identified concentrations exceeding the NR720 state soil standards for at least one (1) dioxin/furan. Of these 19 samples seven (7) also exceeded the NR720 Cumulative Cancer Risk with four (4) also exceeding the WDNR NR720 Cumulative Hazard Index.”

DNR Requiring Additional Testing to Define the Extent of Dioxin Contamination in Riverside Park

On February 24, 2021, Mr. Matt Thompson of the Wisconsin Department of Natural Resources sent an email to the City of Wausau with the subject of “Riverside Rail Corridor BRRTS# 02-37-548785 Additional Sampling Required.” In the email, Mr. Thompson conveys:

“Based on our review, additional sampling is required to define the extent of contamination at the site in the following areas:

North of borings P14 and P15

West-southwest of P1 and P7 to define the cause of exceedances at the culvert inlet

Near R6 and N4-2: Figure 10 shows elevated 2,3,7,8-TCDD TEQ in this area. The source should be better defined.”

The PDF of the DNR email can be accessed directly on our website here or on the DNR’s website here. The communication can also be viewed embedded below.