The limits, known as enforcement standards, can be used to regulate facilities, practices, and activities that can affect groundwater.
More than 60% of state residents obtain their drinking water from groundwater, including many people living in Milwaukee suburbs.
Officials from the Dept. of Health Services (DHS), Dept. of Natural Resources (DNR), and Dept. of Agriculture, Trade and Consumer Protection discussed the recommendations Friday at a news conference in Madison.
The portion of the proposal drawing the most initial attention covers substances known PFAS, or Per- and Polyfluoroalkyl Substances. Those are human-made chemicals found in non-stick cookware, fast food wrappers, firefighting foam, fabric protectors, and other products.
The group Clean Wisconsin says there are at least 18 investigations across Wisconsin into PFAS contamination of drinking water.
Wisconsin officials are proposing an enforcement standard for PFAS that is far more stringent than what the U.S. Environmental Protection Agency recommends.
DHS also wants even tighter limits that could trigger an earlier step — preventive action aimed at protecting the public.
The DNR hasn't revised state groundwater standards in 10 years. The department says it gave a list of substances to DHS and asked DHS to review.
DHS Toxicologist Dr. Sarah Yang told WUWM Friday afternoon that the first thing her team did was to follow a process spelled out in state law and, "Look for all available scientific information." That includes, Yang says, documents from the EPA, or the federal Agency for Toxic Substances and Disease Registry (ATSDR) within the Centers for Disease Control and Prevention, as well as a newer publication that "kind of estimates how people are exposed to PFAS, and how much should be in the water to protect people from that," Yang said.
DHS then created a document describing the rationale for each enforcement standard.
Yang explained why DHS is recommending stricter limits on PFAS than are called for in a federal advisory: "At this time, we're using a lower number because we think that's where the data, the science, is telling us to set the number." Yang says much of the information comes from studies done on animals. "Then, we're trying to estimate how much a person can be exposed to every day, to protect for those effects we saw in animals."
Carly Michaels of Clean Wisconsin called the proposed groundwater standards "a great first step to tackle this issue head on. We're pleased that PFAS pollution is a priority for the Evers Administration during the Year Of Clean Drinking Water,” that was declared earlier by Wisconsin Gov. Tony Evers.
The group Wisconsin Conservation Voters called the standards "long overdue" but said they "set the stage for a comprehensive plan to protect people from dangerous toxic chemicals like PFAS that are linked to cancer, liver damage and thyroid disease."
However, due to a slower administrative rulemaking process started under the Walker Administration, it could take the DNR at least two years for the plan announced Friday to become law.