The US Environmental Protection Agency (EPA) designates Lower Neponset River as a Superfund site

On March 14, 2022,  the Lower Neponset River, between Mother Brook in Hyde Park and the Baker Dam in Milton/Dorchester Lower Mills, was designated as a Superfund site by the EPA. This designation ensures critical federal resources will be available to clean up PCB-contaminated sediments at the bottom of this section of the Neponset River.

The process is expected to involve an extensive study of the contamination and the potential parties responsible for it, opportunities for public input, possible implementation of initial cleanup actions in certain areas, and eventual implementation of comprehensive cleanup efforts.

NepRWA has advocated for the cleanup of this section of the River for almost 20 years and we are excited to see this work getting underway.

Because the contamination is primarily in the mucky organic mud at the bottom of the River, many recreational activities along the Lower Neponset and the Neponset Greenway can continue as usual while the cleanup progresses.

See our FAQs to get more information about PCBs and recreation along the River, as well as a running history of developments and resources related to the cleanup.

For more information, please contact NepRWA Managing Director for Community Resilience, Kerry Snyder at

Stay up-to-date via the EPA project website.

The Lower Neponset River Superfund “site” is defined by the U.S. Environmental Protection Agency (EPA) as the 3.7-mile stretch of the Neponset River from the confluence with Mother Brook in Hyde Park just upstream of Dana Avenue, extending downstream to the Walter Baker Dam located upstream of Adams Street, Dorchester, and Milton.

What is the EPA Superfund Program?

The Superfund Program protects human health and the environment by investigating and cleaning up often abandoned hazardous waste sites and engaging communities throughout the process. Many of these sites are complex and need long-term cleanup actions. Those responsible for contamination are held liable for cleanup costs. EPA strives to return previously contaminated land and groundwater to productive use.

Is it safe to eat FRESHWATER fish caught in the Lower Neponset River?

No. People should not eat fish caught in the freshwater portion of the Lower Neponset River. This includes the area from the Baker Dam in Milton / Dorchester Lower Mills upstream to the Hollingsworth and Vose Dam in Walpole. While the concern over PCB-contaminated sediments only extends upstream to Hyde Park, fish that have spent time in the Lower Neponset can easily swim as far upstream as the dam in Walpole. Because of the process of bioaccumulation, concentrations of PCBs in the fish can be relatively high compared to levels in the river or the water.

Is it safe to go fishing in the Neponset River? What about eating fish from the SALTWATER portion of the River?

You may enjoy recreational, catch and release fishing in all areas of the Neponset River , so long as you don’t eat FRESHWATER fish caught on the Neponset Mainstem as described above. Touching freshwater fish is not a concern. Saltwater fish caught downstream of the Baker Dam in the portion of the Neponset River known as the Neponset River Estuary are not exposed to the higher levels of PCB sediments found further upstream and spend much of their lives in areas other than the Neponset River. Follow general guidelines for all saltwater fish when deciding whether to eat saltwater species caught in the Neponset Estuary. There are no special precautions for consumption of saltwater species caught in the Neponset.

Are there PCBs in the water along the Neponset River?

PCBs do not readily dissolve in water. As a result downstream of Mother Brook there are PCBs in the water, but they are at extremely low levels that are not a concern for human contact. However, you should not drink water taken directly from the Neponset River because of concerns about other pollutants.

May I walk and bike along the Lower Neponset River?

Yes, you may safely walk, bike, and engage in other land-based activities along the Neponset . PCBs are typically found in the “mucky,” organic mud at the bottom of the river. There should be no human health concerns with land-based recreation along the River, except for eating freshwater fish as discussed above.

May I canoe, kayak and boat along the Neponset?

Yes, you may canoe, kayak and boat along the Lower Neponset. PCBs on the Lower Neponset are primarily concentrated in the deep layers of mucky “organic” mud accumulated behind the two dams on the Lower Neponset and a former dam. While boaters might come in contact with mud in the River to a limited degree, this should not be a health concern for several reasons.

First, PCBs in the River are bound to organic matter in the mud and the primary hazard would be eating mud rather than touching mud. Second, areas of the River that have sandy or rocky bottoms without accumulations of mucky organic mud will have minimal if any PCBs because there is little or no organic matter with which the PCBs can bind. Lastly, even in areas of the River that have organic mud deposits near formal canoe launches, the PCB concentrations in surface sediments are generally low. Higher PCB concentrations are found behind the dams several feet or more below the surface of the mud. While the risk of PCB exposure to boaters via mud is limited, we do recommend washing hands and shoes after recreation if you get muddy, as much because of other pollutants as because of PCBs.

Can I swim in the Lower Neponset River?

While our goal is to get all of the Neponset and its tributaries to be safe for swimming all the time, the Lower Neponset River does not yet meet this goal consistently. This is primarily because of remaining problems with sewage pollution and untreated rain runoff from surrounding streets and neighborhoods, though potential exposure to PCBs in mud deposits would also be a concern with swimming in the area between Mother Brook and the Baker Dam. That said, the Lower Neponset often does meet bacterial pollution standards for swimming and almost always meets bacterial standards for boating.

Is there a project website, email list, or some other mechanism to keep track of the project and receive timely notice of meetings or document releases?

An official Superfund website has been created, where overall information will be posted throughout the project. At this time, you can view documents such as the factsheets, etc. at:

ZaNetta Purnell
U.S. EPA Community Involvement Coordinator 617-918-1306

Meghan Cassidy
U.S. EPA Supervisory Environmental Engineer 617-918-1387

General Information

Baker Dam, Milton/Dorchester Lower Mills