Lower amounts of PFAS in Well 16 on Mineral Point Road were thought to have come from a former landfill.

The DNR announced last week that preliminary results suggest those may not be the only sources.

The list of potential sources includes factories, fire stations and landfills, as well as a Far West Side neighborhood that may have been fertilized with sludge from sewage treatment plants in the 1980s.

The study looked at hundreds of parcels within a one-mile radius of the wells and determined the level of risk based on the likelihood of PFAS use and a history of spills or hazardous material releases.

There were 14 high- and 19 medium-risk sites around Well 15 and four high- and eight medium-risk sites around Well 16.

“Before everything was Truax, Truax, Truax,” said Sarah Hoye, communications director for the DNR. “It’s not just Truax.”

Hoye said investigators now will try to contact people connected with the potential sources to find out more about what went on at the sites.

“What were you making? What were you doing?” Hoye said.