With gentle rapids flowing along granite-lined bends, the Neponset River has long been a hidden gem of Boston. But over the years its natural splendor has been badly tarnished, with its rust-colored water concealing toxic sediment and contaminated fish.
Now, after years of lobbying by local and state officials for federal help to clean it up, the US Environmental Protection Agency on Monday will designate a 3.7-mile stretch of the river a Superfund site.
The designation means the EPA will put significant federal dollars, scientific expertise, and legal muscle behind the cleanup, which could cost tens of millions of dollars and take decades.
“We now have a mechanism to clean up the river and protect the health of the communities around it, as well as increasing the overall use and enjoyment of this important resource,” said David Cash, the EPA’s newly appointed regional administrator in New England. “This is a win for families who value recreating on the river, a win for great blue herons, a win for fish, and a win for Massachusetts.”
The Lower Neponset River was fouled by years of pollution from a host of mills and manufacturing plants along its banks in Boston that have made its fish poisonous to eat and its bottom laden with polychlorinated biphenyls, or PCBs, the carcinogenic byproducts of industrial activity that began nearly a century ago.
The stretch of river from Mother Brook in Hyde Park to the Walter Baker Dam in Dorchester is one of 12 sites around the country that EPA officials added to more than 1,300 now listed on the Superfund National Priorities List, which includes 33 others in Massachusetts. The state’s last Superfund site was a contaminated factory in Amesbury designated in 2017.
Mayor Michelle Wu called the river a “natural treasure” and said restoring its ecosystem is vital.
“I look forward to working closely with the Environmental Protection Agency on improving this beautiful resource in Boston,” she said.
EPA scientists said they plan to start collecting thousands of samples from the river this fall, while the agency’s enforcement division, working with the Justice Department, will seek to establish who was responsible for the pollution.
“We intend to initiate a detailed investigation about where the contamination is and what the impacts are,” said Meghan Cassidy, deputy director of the EPA’s Superfund and Emergency Management Division in New England.
There are a number of companies that likely contaminated the river, going back as early as the 1930s, but neither state nor federal officials have sufficient evidence to force them or their successors to pay for the cleanup.
About 15 years ago, after the toxic sediment was first identified, state officials compelled Thomas & Betts Co., a producer of electrical equipment that had acquired a local manufacturing plant for electrical wiring that had contributed to the pollution, to clean a portion of the river in Hyde Park. But officials later discovered that the PCBs were spread in other parts of the river, far more extensively than previously understood.
A study by the US Geological Survey found that 3.7 miles of the river contained PCB contamination. PCBs were commercially manufactured in the United States from 1929 until their production was banned in 1979. Resistant to extreme temperatures and pressure, they were used widely in electrical equipment, hydraulic fluids, and lubricants.
Thomas & Betts later sued other companies that it alleged also contributed to the river’s pollution, and in 2019, after a lot of litigation, a federal appeals court in Boston ruled that other companies had to share in the nearly $13 million cost of the initial cleanup. With such a complicated history of finding who’s responsible for cleaning the rest of the river, the state has deferred enforcement to the federal government, which has much greater legal firepower and ability to assign blame.
Cassidy said the work will proceed, even if the agency doesn’t identify a responsible party.
“We’re pretty optimistic that we won’t see a delay,” she said.
But it’s unclear how long the project will take.
“We have to do a very thorough investigation before we figure out the appropriate remediation,” she said. “We do know that these complicated, large sites take some time. It’s not unlikely it could take decades.”
Local residents, officials, and environmental advocates said they were grateful for the federal help.
“It’s exciting to know the EPA is taking charge,” said Melanie Daye, president of the Hyde Park Central River Neighborhood Group.
Kathleen Conlon, chair of the select board in Milton, which abuts the river, said she hopes the cleanup will “restore a healthy natural habitat for wildlife and increase recreational opportunities for the public.”
Senator Ed Markey, in a statement, called the EPA’s designation “an important step toward ensuring that the river receives the resources and attention it needs to be restored.”
Ian Cooke, executive director of the Neponset River Watershed Association, hopes the cleanup will include the removal of old, unused dams; the return of significant herring and shad runs; and eventually fishing and swimming.
As he paddled down the river last September, there were signs that the challenges of restoring the river may go well beyond removing PCBs, with trash and remnants of sewage visible along the shore.
He also wondered whether the EPA would find PCBs farther down the river, in an estuary beyond the 3.7-mile Superfund site.
“It’s fantastic to see EPA stepping up to lead this project,” he said. “We look forward to working with them and keeping the pressure on to move things along quickly.”