EAU CLAIRE — Three more city wells have been taken offline as the public utility continues its efforts to keep PFAS chemicals out of Eau Claire’s drinking water.

Out of the city’s 16 wells, four were shut down in early July when PFAS were detected in them, and then three additional ones were idled between mid-July and mid-August. Since then, the city has been continuing to take other steps to contain PFAS.

“In fact the situation has improved over the past couple weeks,” said Lane Berg, city utilities manager.

On Sept. 28, the city resumed pumping from three of the previously shut down wells, but sent water from them into holding lagoons instead of Eau Claire’s treatment plant. That is being done to prevent PFAS from sitting in those wells and potentially migrating to others nearby that remain in production.

In the last two weeks PFAS levels fell in the water system, according to tests the city has had done. There were 0.328 parts per trillion of PFAS in samples taken on Sept. 29, but that declined to 0.204 parts per trillion a week ago(Oct. 6).

Ever since the city announced small amounts of PFAS were found in a few of its wells on July 12, Berg noted that Eau Claire has continued to have plenty of safe drinking water for residents.

“The city has ample water supply from its active wells and the Water Utility has continued to deliver water to our residents and consumers satisfying all volume needs while meeting all federal and state safe drinking standards as well as all DNR proposed Recommended Enforcement Standards for PFAS and related chemicals,” Berg said Tuesday in a statement.

Eau Claire uses an average of 9 million gallons of treated water a day. On Tuesday, the city only needed to run five of its wells to produce 10 million gallons to keep water towers and reservoirs full.

“We’ve got a lot of redundancy built into our system,” Berg said.

PFAS are a group of chemicals used since the 1950s in the production of non-stick cookware, fast food wrappers, stain-resistant sprays and some kinds of firefighting foams.

It’s that last category that the state Department of Natural Resources suspects is the potential source affecting Eau Claire’s municipal wellfield.

The agency sent a letter in early August to Chippewa Valley Regional Airport — located near the wellfield — suspecting that its use of firefighting foam is a potential contributor to PFAS affecting city wells.

“There’s nothing between the wells and the airport that could’ve caused this,” said Matt Thompson, a hydrogeologist with the DNR.

He noted that foam used to fight fires at airports, as well as its use in training and testing, have been linked to PFAS contamination elsewhere in the state.

The local airport is so far the only entity that has gotten a letter identifying it as a potential source of the city well’s PFAS contamination, Thompson said.

The airport has hired an environmental consultant to draft a work plan for dealing with the PFAS contamination, he said. A report is expected to come out in a few weeks.

If the airport is shown to be the cause of the contamination, it will be responsible for taking care of the impacts its PFAS use has had, Thompson said. That could include a filtration system to clean the chemicals out of the public wells.

The city has hired Gannett Fleming, an engineering firm, to map the PFAS flume in the wellfield. By the end of the year, the city expects to have that consultant’s report to determine what needs to be done as a long-term solution for getting rid of the contaminants, Berg said.

“That will really be our driving force,” he said.

Thompson, who is based out of the DNR’s Eau Claire office, said the city is taking the necessary steps to ensure drinking water remains safe.

“The city is testing their water so it is safe for consumption and use,” he said. “They’ve got safe water in the city of Eau Claire.”

PFAS are known as “forever chemicals” because they don’t break down in the environment.

Scientists are still studying health effects of various PFAS on humans, the state Department of Health Services states on its website. Not all PFAS have the same health effects, but research suggests that high levels of certain chemicals may raise cholesterol levels, decrease how well bodies respond to vaccines, increase risk of thyroid disease, lower fertility in women, increase risk of conditions including high blood pressure in pregnant women, and result in slightly lower infant birth weights.

Contact: 715-833-9204, andrew.dowd@ecpc.com, @ADowd_LT on Twitter