A $187 to $267M settlement will address toxic waste dumped into the Penobscot River starting in 1967
Clean sand will cover mercury-contaminated sediment in the riverbed. Photo by Unsplash.
Nov. 11, 2026
By Hank Austin
The Penobscot River has been contaminated ever since a chemical plant in Orrington dumped 6 to 12 metric tons of mercury into the estuary from 1967 to 1972. After decades of legal battles, actions are now being taken to address the situation.
The Penobscot Estuary Mercury Remediation Trust is carrying out a pilot project to isolate mercury-contaminated sediment on the riverbed by covering it in four- to six-inch layers of clean sand. Appointed by the U.S. District Court, the trust is responsible for managing the funds and implementing the remedies outlined in the consent decree, a settlement agreement made by a judge with the consent of both parties. The lawsuit was filed by the Maine Peoples Alliance and the Natural Resources Defense Council.
During August and September of 2026, environmental services firm J.F. Brennan successfully capped six acres of contaminated intertidal sediment with 9,400 tons of sand in Orrington, near Picnic Park. According to the court’s Phase III Engineering Report, the process, known as thin layer capping, is more cost-effective and nondisruptive to the environment than dredging– excavation of debris from the bottom of a body of water.
The caps will be monitored for the next three to five years to evaluate if they’re effective and stable against the current.
Remediation trust program manager, Lauri Gorton, said, “The Penobscot's a very powerful river. So we've chosen a small-scale pilot to evaluate if the cap is stable and will stay in place long enough to create a benefit.”
Thin layer capping is the first physical step in remediating the Penobscot River following updated sampling of the sediments, preliminary designs on caps, and submission of a permit application for the pilot, according to Gorton. This follows a settlement being reached between Mallinckrodt US LLC, the Maine People’s Alliance, and the Natural Resources Defense Council in 2022.
Initial leak and settlement
From 1967 until 2000, the HoltraChem Manufacturing Company operated a 235-acre site in Orrington on the Penobscot River. Founded by Mallinckrodt Inc., the facility manufactured chlorine, sodium hydroxide, sodium hypochlorite, hydrochloric acid, and chloropicrin, primarily for use in the paper and pulp industry.
The plant directly dumped mercury into the Penobscot River Estuary for five years.
The World Health Organization ranks mercury as “one of the top ten chemicals of major public health concern.”
On Oct. 18, 1972, Congress passed the federal Clean Water Act over then-President Richard Nixon’s veto. The law, an overhaul of the 1948 Federal Water Pollution Control Act, aimed to restore and maintain the nation’s surface waters. The act made it illegal to dump pollutants into navigable waters without a permit, and funded wastewater treatment plants across the country, according to the EPA.
This halted the direct mercury dumping, but the plant continued to leak mercury until its closure in 2000, according to The Sierra Club.
In 2000, the Natural Resources Defense Council and the Maine People’s Alliance filed suit against Holtrachem and Mallinckrodt, alleging that the company caused “imminent and substantial endangerment to health and the environment.”
The plant filed for bankruptcy and shut down in 2000 due to operational challenges stemming from a heavy reliance on mercury, in conflict with environmental regulations and the legal actions taken against them. In 2002, they were found liable for mercury pollution.
Between 2000 and 2022, Mallinckrodt fought the legal action against them, leading this case to become the longest-running active environmental lawsuit in the history of Maine’s federal court.
The court ordered the company to fund an independent study of the Penobscot River estuary. From 2007-2016, an independent panel of scientists conducted a study and found that mercury levels were 10-20 times higher than neighboring regions.
In 2014, the Maine Department of Marine Resources enacted an emergency ban on commercial lobstering and crabbing over a 7-square-mile radius in the lower Penobscot due to the findings of the panel. In 2016, the ban expanded by an additional 5.5 square miles.
Once the findings were accepted by the court, an independent engineering firm was hired to find the best approach to remediation. In 2018, they delivered their proposal to the court.
Mallinckrodt, Natural Resources Defense Council, and Maine People’s Alliance negotiated the terms of resolution for four years until a settlement of between $187 and $267 million dollars was reached in 2022. The funds were entrusted to an independent trustee, Greenfield Environmental Trust Group.
The settlement reached in the lawsuit outlines $70 million for targeted removal, $50 million for capping, $30 million for work on the Orland River and the East Channel, $20 million for environmental projects beneficial to the public, and $10 million for 30 to 45 years of monitoring.
There are currently no swimming advisories on the Penobscot or Orland River from the Maine Department of Environmental Protection, but the Maine CDC does directly warn Mainers not to eat fish caught from these rivers.
James Palkie of Bucksport, Maine, has been swimming in the Orland River for years and never knew of the mercury contamination. “I had absolutely no idea….That’s news to me,” Palkie said.”
Swimming in mercury-contaminated rivers is generally considered safe due to poor skin absorption and the mercury binding tightly with the sediment on the riverbed, according to the US Geological Survey, but it is recommended not to disturb or accidentally ingest the sediment.
“Ah, well, the sad thing is, I do love jumping off the Orland bridge and, you know, swimming in there, so it's like I wouldn't want them to close it down, but I don't know. They might have to just not allow people to go in there for a while until the levels go back down,” Palkie said.
