August Spill Prompts Expanded PFAS Monitoring in Casco Bay

In mid-August, around 50,000 gallons of firefighting foam, a frothy mix of water and chemicals including PFAS, was accidentally released from the former Brunswick Naval Air Station. It entered the stormwater system, eventually flowing into Harpswell Cove. Organizations across the state, including Bigelow Laboratory, jumped into action to document the spill of these potentially harmful chemicals.

Fortunately, Bigelow Laboratory, in partnership with Friends of Casco Bay, has been regularly monitoring levels of PFAS, the so-called forever chemicals, in the area since May 2023. The ongoing project is enabling scientists to determine baseline levels of PFAS for the region, identify sources of these chemicals into Casco Bay, and illuminate their fate in water. This fall, the research team, led by Senior Research Scientist Christoph Aeppli, received additional funding from the EPA to expand where and how often they were monitoring to document the long-term impact of the spill.

As expected, they’ve seen increased levels of PFAS since the spill throughout Harpswell Cove, and levels have remained elevated. But they are beginning to see pollutant concentrations decreasing close to the original source of the spill, highlighting the need to better understand how fast these chemicals move and mix in a tidal coastal environment.

“It’s going to take time to flush out the system, which is why it’s so important to do this monitoring year-round,” Aeppli said. “Bigelow Laboratory has this expertise and testing capacity and is networked with all of these groups active in the area, which will help us better understand this complex system and, ultimately, determine the impact of the spill.”

The larger project began in 2023 with support from Maine Sea Grant. EPA’s National Estuary Program, via the nonprofit Restore America’s Estuaries, then funded the team to increase monitoring in 2024-2025. The goal is to identify specific PFAS sources and to expand data collection to coastal sediment, which can absorb PFAS and serve as an ongoing reservoir for the pollutants.

The team originally chose 80 sites across Casco Bay to monitor three times a year, through a stakeholder engagement process managed by Friends of Casco Bay. With the new post-spill funding, they’ve added eight sites for more frequent monitoring through next fall. That additional data will provide insight on how the chemicals from the spill pulse in and out of Harpswell Cove with the tide and eventually dilute as they mix into Casco Bay in the coming months. Understanding that process is invaluable given the lack of existing information on how PFAS chemicals enter and move from land to the ocean through coastal environments.

“Right now, we are all worried about PFAS,” said Heather Kenyon, Friends of Casco Bay’s policy and science associate, who led the stakeholder process that guided the study. “This information will help us act to reduce this threat.”

The team’s monitoring will complement the data collection of the EPA and the Navy at Brunswick Naval Air Station, which is a designated Superfund Site, and of the Maine Department of Environmental Protection, which is managing spill response. Coupled with the baseline monitoring that Bigelow Laboratory and Friends of Casco Bay began last year, the information will enable scientists and managers to put the spill in context with all of the ongoing sources of PFAS across the region, such as agricultural and stormwater runoff.

“PFAS come from so many places and end up in the environment through so many different pathways, but this study is going to really help us understand their movement and fate in Casco Bay,” Aeppli said. “PFAS isn’t a Maine-specific problem, and other states will also be able to learn a lot from the data we’re gathering.”

Aeppli added that providing this information and, critically, highlighting when and where things are getting better will also help communities make more informed, science-based decisions about how to manage PFAS pollution and any future incidents.

“We can’t act to protect Casco Bay without data that tells us where PFAS is a problem,” said Casco Baykeeper Ivy Frignoca. “We are honored to work with Bigelow Laboratory to develop the first multi-year data set for this purpose and to hone in on the effects of the Brunswick spill.”

Photo Caption:

Bigelow Laboratory Research Technician Hannah Sterling collects water samples as part of an intensified effort to monitor levels and track sources of PFAS following the accidental spill of the chemicals in August 2024 (Credit: Christoph Aeppli).