3M has agreed to widespread water testing and treatment for people living near its Cordova, Ill., factory after the U.S. Environmental Protection Agency found that contamination from PFAS there has created "an imminent and substantial endangerment" of drinking water supplies.

The requirement, part of an EPA administrative order, comes as the agency is accelerating its response to perfluoroalkyl and polyfluoroalkyl substances, collectively known as PFAS. This move towards regulation and a flood of lawsuits based on the health effects of the chemicals present a mounting cost for Maplewood-based 3M, which developed the compounds and uses them in products like the water and stain protector Scotchgard.

"Communities have suffered far too long from exposure to these chemicals," EPA Administrator Michael S. Regan said in a statement. "This settlement is a critical step forward in our work to protect communities from pollution and hold polluters accountable for their actions."

In a statement, John Banovetz, an executive vice president at 3M, said that "this agreement demonstrates the positive impact that engagement between regulators and 3M can have for communities, and we appreciate the EPA's work to reach this milestone."

3M spokesman Grant Thompson declined to say how much the testing and treatment would cost the company. When those numbers are "probable and reasonably estimable," they'll be shared in investor filings, he wrote in an email.

"3M has, and will continue to, share these in filings with the [Securities and Exchange Commission] and related communications with investors and the public," Thompson wrote.

The firm's Cordova plant is beside the Mississippi River just north of the Quad Cities area, on the Iowa border. It was permitted to discharge wastewater into the river by the EPA, with a requirement to monitor PFAS levels, but in 2019 the company told the agency it was releasing more of the chemicals than it had previously reported. In all, the order notes that at least "60 PFAS analytes" were released into the air, water and soil around the plant.

David Cwiertny, a University of Iowa engineering professor and director of the Center for Health Effects of Environmental Contamination, said Friday that he's glad 3M is being held accountable for PFAS in drinking water around the Cordova plant.

"These folks are unfortunate to be very near a 3M facility, but at least we're helping them," Cwiertny said.

He wonders where there might be similar contamination.

"The only way you can try to get your hands around a problem is to figure out where the chemicals were used and where they are coming from," Cwiertny said.

The company was independently testing some of the water sources around Cordova as early as July and offering treatment through granulated activated carbon filters.

Now, 3M is required by the EPA to test all private wells within 3 miles of the Cordova plant and public water systems up to 10 miles away. Some of the municipal systems that will be tested include East Moline, Moline, and Rock Island in Illinois; and Davenport, Iowa.

"This is a comprehensive effort to address PFAS contamination in drinking water systems that is near the Cordova facility and to sample public water systems in an area that further expands from the facility," Diana Saenz, the acting director of the water enforcement division at the EPA, said in an interview.

An estimated 293,600 people connected to public water systems will have their water tested, according to EPA spokeswoman Melissa Sullivan. EPA did not have an estimate for how many people with private wells will receive testing.

The Cordova order has echoes in the Twin Cities, where 3M was found to have contaminated groundwater with the same class of chemicals in the area around its Cottage Grove plant in the east metro.

About 150 square miles in Washington County is covered by a plume of PFAS-tainted groundwater, affecting about 170,000 people. The state of Minnesota settled with 3M for $850 million, which is being used for water quality projects.

Lori Swanson, who was Minnesota attorney general from 2007 to 2019, litigated the case. In an interview Friday, she said that when the state filed its suit in 2010, the EPA had little interest in the chemicals.

"They were not involved, and I think there has been an evolution on the part of the EPA," said Swanson, now an attorney in private practice. "Nowadays they certainly seem more aggressive."

It wasn't until 2016 that the EPA published its first drinking water notice on the chemicals. Since Regan was confirmed as administrator last year, the agency has pledged to establish enforceable PFAS drinking water standards for the first time and classified two of the chemicals as hazardous under the law that governs Superfund cleanup sites.

PFAS have been linked to health problems such as increased risk of liver, kidney and testicular cancers, decreased fertility and increased blood pressure in pregnant women, according to the EPA. PFAS don't break down readily in the environment and build up in the bodies of those exposed to them, inspiring the nickname "forever chemicals."

Juanpablo Ramirez-Franco of WNIJ Northern Public Radio and Erin Jordan of the Cedar Rapids Gazette contributed to this story.

This story is a product of the Mississippi River Basin Ag & Water Desk, an editorially independent reporting network based at the University of Missouri School of Journalism in partnership with Report for America and the Society of Environmental Journalists, funded by the Walton Family Foundation.

Correction: Previous versions of this story misstated the number of people whose water will be tested for PFAS.