Awareness of PFAS pollutants, which include thousands of different chemicals, has grown in recent years. These molecules degrade slowly, if at all, which is why they’re sometimes called “forever chemicals.” Many are also toxic, with research linking them to cancers and harmful effects on fertility, pregnancy and child development.

PFAS is an abbreviation for a group of chemicals called perfluoroalkyl and polyfluoroalkyl substances. They have been used in nonstick cookware coatings, as water repellents for clothing, and in firefighting foams.

The key elements in these chemicals, carbon and fluorine, form strong bonds, which make PFAS molecules durable and heat-resistant. Those bonds also prevent PFAS from degrading naturally. PFAS chemicals dissolve in water, one of the key ways these pollutants move through environments.

PFAS on military sites

Harpswell is somewhat unusual in Casco Bay in that there are two direct sources of PFAS pollution in its immediate vicinity. Firefighting foams containing PFAS were stored and used at the one-time U.S. Navy fuel depot that is now George J. Mitchell Field, and at the former Brunswick Naval Air Station.

Some foams remain stored in hangars on the former base, and even have spilled in two known recent accidents, in 2011 and 2019, according to David Page, a retired Bowdoin College biochemist and member of an advisory board overseeing the base’s transition from military to civilian property.

Navy officials and others have been addressing PFAS pollution from the former base for years as part of the formal process of selling the land for redevelopment. Efforts have included treating groundwater and dredging contaminated sediment in ponds.

But PFAS pollutants continue to make their way into streams and Harpswell Cove. Maine Department of Environmental Protection scientists detected PFAS in mussels in the cove as far back as 2014, and in May 2024, the Navy said PFAS also were detected in a mussel sample from Woodward Cove. The Navy has not released final results from its shellfish sampling.

PFAS also have been found in finfish, both those living in ponds on the former base and sea-run brook trout in streams below the ponds and in Harpswell Cove.

The Department of Environmental Protection already bans clammers from harvesting shellfish in the upper end of Harpswell Cove because of historically high lead levels. The department’s 2014 and 2016 mussel sampling found PFAS levels that were low enough that people might be able to safely eat the mussels once a week.

But Page, the former Bowdoin professor who has conducted PFAS testing in Harpswell Cove, said PFAS in fish that spend some or all of their lives in the base’s ponds and in Mere Creek worries him more.

“All of the fish in the watershed have PFAS in their tissue that’s high enough to preclude consumption,” he said.

The Department of Environmental Protection publishes advisories about PFAS-contaminated fish in inland waters, but there are currently no federal or state guidelines for a safe-to-eat PFAS level in marine fish.

Fences protect off-limits areas of the former base, but Page said there could be more warnings about swimming or fishing in polluted waters, especially for people who don’t speak English as a first language.

PFAS at Mitchell Field

In Harpswell, PFAS were detected in tests of well water at Mitchell Field, which were organized by the town in 2019. One of the wells was being used at the time to water plots at the Harpswell Community Garden. Soil tests in the garden also found low levels of PFAS, according to Susan Stemper, chair of the garden committee.

Garden users grow for themselves and donate produce to people in need in Harpswell and elsewhere. Stemper said that even though discussions with experts and stakeholders led the committee to believe food grown in the garden was safe to eat, they still decided to stop using the well. That summer, they encouraged volunteers to bring their own water and arranged for deliveries of water by truck.

Subsequently, the committee found another well at Mitchell Field that had tested negative for PFAS. Using donations, they were able to connect to that well instead.

Stemper said the committee will continue to take periodic water and soil samples to monitor PFAS in the garden. She said they get occasional questions about PFAS in the garden, and they are working to keep gardeners and the public informed about what they have done to address the pollutants.

There may be more PFAS pollution at Mitchell Field than what has already been documented, according to a review of the Navy’s cleanup efforts by Harpswell Town Planner Mark Eyerman, which he described to the Mitchell Field Committee in January.

Page also believes there may be pollutant dumps at the site that haven’t been properly investigated.

PFAS in the ocean

PFAS pollution is not limited to the two former Navy properties. The chemicals have been used in so many ways and in so many places that PFAS take countless routes into the environment.

Wastewater is one prominent avenue. Since existing treatment methods don’t break down PFAS, they exit into rivers and other water sources with otherwise clean water. The last several years also have revealed that PFAS were inadvertently spread on farm fields in treated municipal sludge, a commonly used fertilizer.

Rivers and streams inevitably carry the pollutants down to the ocean. When scientists have tested ocean water along Maine’s coast, “we can detect PFAS in every sample,” said Chris Aeppli, a researcher at the Bigelow Laboratory for Ocean Sciences in East Boothbay.

Researchers have found PFAS in ocean samples from the Arctic Sea to Antarctica and everywhere in between. In other words, said Aeppli, Harpswell and Casco Bay are not particular hot spots for PFAS pollution.

Aeppli said the concentrations of PFAS he and his colleagues find in most samples are well below what the U.S. Environmental Protection Agency considers safe for drinking water. And he said the concentrations of PFAS found in seafood are much lower than what the state considers acceptable in freshwater fish.

“Just by living in this world, you probably get more PFAS from other sources than if you eat seafood that has a little bit of PFAS in it,” Aeppli said.

Testing in Casco Bay

Collaborating with Aeppli on PFAS sampling is the organization Friends of Casco Bay. They started sampling last year and have funding from the Environmental Protection Agency to continue their PFAS project this year and in 2025.

The focus in 2024 is understanding where PFAS is entering Casco Bay, said Ivy Frignoca, from Friends of Casco Bay. The team has selected 70 sites throughout the bay, each of which will be sampled three times a year.

Ten or more of the sites are in Harpswell’s waters, selected with input from Harpswell Harbor Master Paul Plummer. The organization has not released results yet.

Plummer said he emphasized sites in Harpswell Cove and near Mitchell Field, but recommended sites in Quahog Bay and near Cundy’s Harbor as well.

He told the Anchor he hasn’t heard much about PFAS from shellfish harvesters, but he expects their concerns will only grow as general awareness of PFAS and their dangers increases. “I think we’re just at the tip of the iceberg,” Plummer said.

The chair of Harpswell’s Conservation Commission, Mary Ann Nahf, said PFAS pollution is not an immediate priority for her committee. When PFAS pollution at Mitchell Field and the former Naval Air Station became apparent, she said, the commission helped put together information for the town’s website.

Emerging solutions

PFAS pollution is pervasive, and the existing evidence suggests it can be a real health concern. At the same time, solutions are emerging. In the case of the Community Garden, access to a different well solved the problem.

Aeppli said residents with wells near shorelines may want to have their water tested for PFAS. If PFAS are detected, sink or countertop water filters can remove them. Consumers should check that the filter has been certified to trap PFAS by a testing company, such as the National Sanitation Foundation.

Page recommends filtering drinking water as well. He acknowledged that PFAS pollution can be scary, but said he is cautiously optimistic that scientists will develop ways to break down PFAS into safer chemicals in the next few years.

Sam Lemonick is a freelance reporter. He lives in Cundy’s Harbor.