PFAS
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PFOA/PFAS Information

The Tomahawk Waterworks continues its mission to provide safe, high quality drinking water that meets all federal and state standards.  Safe drinking water is essential to ensure public health.

What are PFAS?

PFAS (per- and polyfluoroalkyl substances) are a group of human-made chemicals used for decades in numerous products, including non-stick cookware, wrappers, stain-resistant sprays, and certain types of firefighting foam.  These contaminants have made their way into the environment through accidental spills of PFAS-containing materials, discharges of PFAS containing wastewater from treatment plants and certain types of firefighting foam.

PFAS does not breakdown in the environment and have been discovered at concentrations of concern in groundwater, surface water and drinking water.  These chemicals are known to accumulate in the human body, posing several risks to human health including certain cancers, liver damage and decreased fertility.  Information about PFAS can also be found on the DNR and DHS PFAS websites.

What are we doing?

Tomahawk Waterworks is not in violation of any federal or state drinking standards or regulations.  We are taking actions to be proactive to protect the health of its customers by doing the following:

  • Conduct quarterly tests of the water distribution system for PFAS and posting those results as soon as they are available on our website.
    • Additional testing above the required testing from the DNR is being started to help understand current conditions and changes in PFAS levels. These additional test results will be available below as soon as they are received.
  • Follow scientific framework of the EPA and DNR for best water quality practices.
  • Identifying any operational changes that can be made to reduce the amount of PFAS in the drinking water.
  • Investigating long-term treatment solutions.  Both of the option below require installation of additional infrastructure.
    • Treatment and/or filtration of Well 4 and Well 5.
    • Exploring option for additional well sites.  A new well site was identified in 2012, tested and approved for water quality and supply.  Tomahawk Waterworks is in the process of retesting the new well site for PFOA/PFAS and other water quality standards to see if this well site is a viable option.

How does DHS determine a health risk exists?


Department of Health Services (DHS) reviews the best available science to make recommendations and issue public health advice to protect human health.  After reviewing and assessing the implication for human health based on exposure to PFAS through drinking water, DHS has issued drinking water health advisory levels for 18 PFAS, whether the water comes from a public water system or well.

DHS uses a tool called the hazard index to also assess implications for human health based on exposure to a mixture of PFAS.  The health index is calculated by comparing the levels of each PFAS found in the water sampling during laboratory analysis to their corresponding drinking water health advisory level and adding these ratios together.  This online tool can be used to determine the hazard index of a water sample.  

A hazard index equal to or greater than 1.0 indicates that the water may pose a health risk.

Drinking Water Advisory

Tomahawk Waterworks is not in violation of any federal or state drinking water standards or regulations and has taken actions proactively to inform and protect the health of its customers.

Tomahawk has two wells that supply water to its customers (Well 4 and Well 5). The wells are located 75’ apart and draw water from the same aquifer. On both 4/18/2023 and 9/07/2023, Tomahawk Waterworks collected water samples of the Tomahawk Waterworks drinking water and tested them for perfluoroalkyl and polyfluoroalkyl substances (PFAS). PFAS are a group of man-made chemicals that have been used in many products since the 1950s. 

 As shown in the table below, testing showed PFAS below the EPA and WDNR regulatory limit of 70ppt on both 4/18/2023 and 9/7/2023.  Wisconsin DHS Health advisory limits are lower than EPA and WDNR regulatory limits.  PFAS compounds in both well 4 and well 5 were present at levels above health-based standards recommended by the WI Department of Health Services (DHS) on 9/7/2023. Sample results are available: https://apps.dnr.wi.gov/dwsportalpub/DS/View/147590

To read the full Drinking Water Advisory, CLICK HERE

Tomahawk Waterwork Test Results: