About a decade ago, Minnesota Department of Health researchers began testing samples of drinking water in cities where firefighters had used fire suppression foam during training exercises, usually near airports and military bases. They wanted to know if chemicals from the firefighting foam had made it into the water supply.
One of those cities was Bemidji: Its wells are next to the airport, where firefighters had used the aqueous film-forming foam for decades.
At first, it looked as though Bemidji was in the clear. There were trace amounts of chemicals from the firefighting foam in the city's wells, but the concentrations were within the limits of what the state health department at the time considered safe.
Over the next few years, two things changed: Researchers got better at detecting the chemicals, broadly known as perfluoroalkyl and polyfluoroalkyl substances — or PFAS. And the level of PFAS that health officials considered safe got a lot lower.
So Bemidji stopped using in two of its five city wells. It started blending water from the three remaining wells to keep the PFAS levels within the new safe range.
And for a while, that worked.
But in water tests the state health department administers four times a year, those PFAS levels started to inch higher. City officials wanted a new, clean water source in case that trend continues.
"They're able to get by right now with limited pumping of three wells," said Todd Johnson, regional engineering supervisor for the Minnesota Department of Health's drinking water program. "But they don't want to live on the edge."
Now, Bemidji is getting ready to dig a new well. The city expects it to be in operation later this year. And it will be far enough north of the airport to make sure the water is free from contamination.
The $2 million price tag on the project, which will break ground later this year, will likely mean city residents will pay higher water rates in the future to cover some of that cost.
Bemidji is just one of many cities across the United States dealing with the expensive environmental fallout from PFAS, which are known for being some of the most resilient chemicals ever created.
They have been used in a variety of industrial and consumer products — nonstick cookware, stain and water repellents for clothing and furniture, food wrappers and firefighting foam — since the 1950s.
But the properties that make them useful — their tendencies to repel oil and water and not to degrade over time — also makes them a big problem for the environment — and for humans.
"We do know that these chemicals just don't break down," said Matt Simcik, a University of Minnesota professor who has done extensive research on PFAS. "So once we've made them, they're around forever."
About 20 years ago, studies found that PFAS were showing up around the globe: in water, soil, wildlife and even in humans. Scientists are still studying the health effects of the chemicals, but research has linked prolonged exposure to PFAS to health problems including some cancers, thyroid disease and infertility.
"There's strong evidence they have adverse biological effects," said Bill Arnold, a University of Minnesota professor who has studied methods to remove PFAS from water. "The data isn't 100 percent conclusive, but the prevailing wisdom is that it's not good to have them in your bloodstream. And we all have them in our bloodstream."
If this all sounds familiar, it's because Minnesota has been on the front lines in this war over chemicals.
Minnesota's 3M Company manufactured PFAS at its plant in Cottage Grove, Minn., for decades, beginning in the 1950s.
The company legally disposed of its waste containing perfluorochemicals in landfills in the eastern suburbs of the Twin Cities metro area. The chemicals leached into the groundwater in nearby cities like Woodbury, Oakdale, Cottage Grove and Lake Elmo.
In 2010, Minnesota sued 3M for natural resource damages from the chemicals, known then in the scientific community as perfluorochemicals, or PFCs. The high-profile case settled last year when 3M agreed to pay $850 million to provide safe drinking water and clean up contamination in the east metro.
3M and other manufacturers stopped making two of the most well-known PFAS chemicals — perfluorooctanoic acid, or PFOA, and perfluorooctane sulfonate, or PFOS — more than a decade ago.
But PFAS is a huge class of chemicals that includes more than 4,000 different compounds, most of which are unregulated. The science surrounding them is relatively new, and scientists are still trying to understand their risks.
"It's really an incredibly large family of chemicals," said David Andrews, senior scientist with the nonprofit Environmental Working Group. "And the underlying concern here is that all of them may have the potential to impact health in a negative way."
3M, DuPont and other companies are facing lawsuits across the country — in Colorado, Michigan, New York, Pennsylvania, Massachusetts and New Jersey — over PFAS contamination in water supplies.
"This is not a Minnesota issue anymore," Simcik said. "Any place those things were used, stored, spilled ... you're going to have the environmental contamination."
Facing growing concern over the health impacts of PFAS, the U.S. Environmental Protection Agency set health advisory levels in 2016 for PFOA and PFOS at 70 parts per trillion — below that limit, researchers don't expect to see adverse health effects over a lifetime of exposure to the chemical.
But there are still no enforceable federal limits on PFAS in drinking water.
There's been growing pressure on the federal government to take action. Congress created a bipartisan task force last month to deal with the PFAS issue. The EPA is working on a PFAS management plan that is scheduled to be released Thursday.
In the meantime, several states, including Minnesota, have stepped in and set their own allowable levels for PFAS in drinking water, some of which are stricter than the federal government's recommendations.
In 2017, Minnesota tightened its guidelines for the two best-known chemicals, PFOS and PFOA, that are about half what the federal government suggests. That adjustment is what pushed some cities' wells, including Bemidji's, over the state limit.
The evolving research and changing standards have created an unsettled atmosphere for city water managers and health officials.
A recent forum on PFAS in West St. Paul, sponsored by the environmental nonprofit Minnesota Brownfields, drew a standing-room-only crowd. Jim Kelly, who runs the state Health Department's environmental surveillance and assessment programs, acknowledged that researchers' improved ability to analyze the chemicals in water might make it seem as though PFAS are "somehow moving and changing."
"That's adding to this idea that we're finding them everywhere now," he said. "Well, maybe we are. But I think they were there for a very long period of time. It's just our ability to detect them has changed."
As concern over PFOA and PFOS has grown, some companies have switched to using alternative PFAS chemicals that are thought to be less toxic.
Both PFOA and PFOS are made of long chains of carbon atoms. The compounds companies are using in their place tend to have shorter carbon chains — "the idea being that one can eliminate it from their body much quicker," Simcik said. The problem is that it also makes them move around much more in the environment, he said.
Andrews said he worries that from what scientists have gleaned about the replacement chemicals companies are beginning to use, "it really seems like a lot of the same mistakes have been made again."
"This really points to a bigger problem: the adequacy of our federal government to regulate industrial chemicals and assure the safety of those chemicals before they're on the market or before they contaminate the globe," he said.
In response to an interview request, a 3M spokesperson said in a statement that the company "takes thorough steps to ensure our products are safe for their intended use and limit their environmental footprint."
"Today, we manufacture and sell a newer generation of PFAS-based materials that play an important role in many applications with industrial or social significance, including electronics, medical devices and low emissions vehicles," the 3M statement said.
Firefighting foam containing PFAS was widely used at airports, military bases and other training sites until recently. Bemidji stopped using it several years ago. But in some places, it's still in use.
"Essentially, almost every airport has had some form of this foam used or tested at some point in its history," said Brian LeMon, an engineer with the Barr Engineering Company, which is working with the city of Bemidji on the well project.
So no matter what happens with government regulations, it's likely that more communities across the country will be dealing with the impacts of PFAS.
So far, Bemidji is the only Minnesota city that has been forced to find a new municipal water source because of water contamination from firefighting foam. But Arnold said it may not be the last. He said water suppliers may not be testing for unregulated PFAS.
"Unless you go and look for the chemicals, you're not going to find them," he said.
For cities facing PFAS contamination, the options are to install a treatment system, which usually includes using activated carbon or reverse osmosis to clean up the water — or find a new source of drinking water.
Both options can be costly, and neither is a long-term solution.
"It's fine if you treat someone's drinking water," Simcik said, "but you haven't done anything about the problem."