When Bemidji learned a few years ago that one of its drinking water wells was contaminated with the man-made chemicals known as PFAS, city officials swiftly shut it down.

Then they shut down another well.

And another.

Now, running on just two of its five wells, Bemidji has hired an environmental law specialist to explore legal options and is looking at building a $16.5 million treatment plant to get the harmful chemicals out of its water. How it will pay for that isn't clear.

"There's no way we can raise utility rates 50 percent," said Public Works Director Craig Gray.

Bemidji is one of about eight sites across Minnesota where water was contaminated by PFAS-laden firefighting foams, including airports and an oil refinery, although it's the only city whose water supply was contaminated by them.

Bemidji's predicament is one more example of the environmental damage wrought by the oldest PFAS, the "forever chemicals" manufactured by 3M Co. and other companies between the 1950s and 2002.

The chemicals became famous as ingredients for nonstick products such as Scotchgard and Teflon, and their environmental legacy in Minnesota is best known for water contamination near old 3M sites and places the company dumped waste in Cottage Grove and other east metro suburbs.

But PFAS compounds were also a key ingredient in firefighting foams widely used around Minnesota and across the country for years and are now the subject of mass litigation nationally. 3M says it no longer makes or sells those foams, although it continues to manufacture newer types of PFAS for other uses.

These "Class B" fire suppressants are great at snuffing out liquid chemical fires, such as those involving jet fuel. The PFAS compounds in them form a suffocating film over the fuel, preventing oxygen from feeding the fire. In fact, military sites and FAA-regulated airports, including the Bemidji Regional Airport, are required to use foams with PFAS, although federal agencies are researching alternatives.

But while Minnesota reached a $850 million settlement with 3M last year over environmental damage from PFAS, the sites polluted by fire suppressants were not a focus. The settlement gives top priority to drinking water in the east metro area. Bemidji might seek an amendment to the 3M settlement to be included.

Fridley, meanwhile, is spending $40,000 to determine the source of PFAS in its now-closed well No. 10. Firefighting foam is a candidate, but the city is still not certain. In the western suburbs, a group of volunteer firefighting departments wants to clean up their old training site, which is fenced off and sitting idle in Carver County.

The Minnesota Air National Guard is investigating the extent of PFAS contamination at its base at Duluth International Airport, where the chemicals have leached into two private wells and led to a fish consumption advisory for nearby Wild Rice Lake. And the Minnesota Army National Guard is probing potential contamination at sites in St. Paul, St. Cloud and Camp Ripley. The Department of Defense is expected to finance any military cleanups.

PFAS is a family of chemicals prized by industry for their ability to repel water and oil. The older compounds are associated with a range of health effects including certain cancers, thyroid problems and reproductive problems. Bemidji's wells were closed after they were found to be close to or above the state's health limits for the compounds.

In terms of human health, regulators have given most of Minnesota's firefighting foam sites an OK after assessing them a decade ago.

"They've either been investigated or we're in the process of looking at them," said Ginny Yingling, a state Health Department hydrogeologist and PFAS authority. "Most of them, we've been able to say it doesn't pose any risk.

"We're probably at the seventh-inning stretch."

The risk to the rest of the environment, however, remains unclear. The Minnesota Pollution Control Agency (MPCA) says it still needs to fully study some of the sites, which it plans to do this year, said Jamie Wallerstedt, a site remediation manager.

"We're still trying to wrap our arms around these sites with regard to eco risks."

Protecting water supply

Bemidji was particularly vulnerable.

When crews dug its wells in the 1950s and '60s, the land near the airport was a great spot with good water, said Gray, the public works director. As a result, all five of the city's wells are at the airport, where firefighters trained for years with Class B firefighting foams.

The PFAS there don't appear to have spread off-site, and private wells nearby aren't contaminated, health officials say. Gray said he's not aware of anyone whose health has been affected and that the current water supply is perfectly safe.

Still, he said, Bemidji needs to ensure its future water supply.

"We don't want to be here with just two wells long term," Gray said.

Bemidji's Fire Department no longer trains at the airport. At one point, crews switched to training with dish soap, state reports show. They now use a newer Class B formulation with a type of PFAS — a short-chain "C6" compound — that's considered safer, said Fire Chief Dave Hoefer.

FAA regulations require the airport, which recently got its own fire department, to use firefighting foams with PFAS. The concentrate is stored in a tank on the fire truck, but it's not used for training, said Karen Weller, the airport's chief executive.

Three hours to the east, the Minnesota Air National Guard continues to investigate significant PFAS contamination at its Duluth airport base. The airport lies next to wetlands, as well as ditches and creeks that drain to Wild Rice Lake and to Miller Creek, which flows to Lake Superior.

A recent Guard report showed that the PFAS contamination is "definitely more extensive" than previously thought, said Mark Elliott, an MPCA project hydrologist.

Guard spokesman Scott Hawks said it's "unlikely" that private wells were contaminated. "However," he said, "PFAS concentrations detected in groundwater near the edge of the installation warrants a [remedial investigation]."

The MPCA has found two private wells near the site that tested above PFAS safety limits. One of the families must use bottled water and will need a filtration system. The second may have to do the same.

PFAS have also turned up in samples of surface water and fish tissue in Miller Creek and Wild Rice Lake, a popular fishing spot, Elliott said. The concentrations were "very low," he said, but the state recommended that people limit their consumption of fish from the lake. Wild Rice Lake flows into Fish Lake, which also has an advisory on fish consumption because of PFAS.

Minnesota this year banned training with firefighting foams containing PFAS, restricting use to fire emergencies, except at airports and military sites.

Mound Fire Chief Greg Pederson said he doesn't know any local departments that still use the chemicals. But they used to, and Pederson has fought for two decades to get a 6-acre site in Carver County cleaned up for environmental reasons.

The site is part of the abandoned Nike missile launch site near St. Bonifacius. A group of west metro volunteer fire departments bought the site in the 1970s and trained there, as did crews from Xcel Energy and Centerpoint, he said.

Monitoring wells show high levels of PFAS at the site, but state health officials said the chemicals have never been detected in any private wells nearby.

That's good news, but Pederson said his group is frustrated that they cannot get agreement on who should pay for cleanup. Democratic U.S. Rep. Dean Phillips, whose district covers the old missile site, included an amendment to the 2020 defense bill requiring the Department of Defense and U.S. Army to identify all sites contaminated by PFAS from firefighting foams and provide a cleanup plan.

Whatever the funding source, Pederson said his group wants to sell the land or hand it back to the Defense Department, but he and others in the group also feel responsible for cleaning it up.

"It's kind of a little black eye for the fire service," he said.

Jennifer Bjorhus • 612-673-4683