The US Environmental Protection Agency has designated the Lower Neponset River as a Superfund Site
NepRWA is committing extensive staff and financial resources to ensure the cleanup of the Lower Neponset River Superfund Site is done right and lives up to its transformative potential.
Upcoming Public Meetings
Latest Superfund News
Additional Information
See our FAQs below for more information about PCBs and recreation along the River.
NepRWA’s Role
NepRWA is dedicating staff time and financial resources to ensure the cleanup is done right.
We’re performing technical and regulatory reviews to ensure the cleanup protects public health, improves
recreation, and supports healthy fish and wildlife, including passage for herring and shad.
We’re also working to ensure the Community Advisory Group provides a strong voice for local residents, and that state and local agencies do their part.
- Stay up-to-date and sign up for the EPA mailing list.
- Visit the EPA Lower Neponset project web page.
- Learn about the EPA Superfund Program
Get Involved!
The Lower Neponset River Superfund Community Advisory Group (CAG) is made up of community members and stakeholders from the Lower Neponset Superfund Site.
The group provides valuable input to the EPA throughout the Superfund cleanup process.
The CAG meets on the third Tuesday of each month at various locations and aims to ensure representation from all four communities near the Site (Hyde Park, Mattapan, Dorchester, and Milton). We welcome more members to represent these areas.
Get more information about the CAG here.
Questions? Please email NepRWA Community Engagement Strategist Karen Groce-Horan.
Project Site

Cleanup Phases
Phase I of the cleanup includes the first mile of the Site between Mother Brook and the T&H Dam in Hyde Park and Milton.
This is the most contaminated stretch, and it will be cleaned up through an accelerated process at an estimated cost of $80 million.
Both riverbanks and the entire river bottom will be extensively excavated and reconstructed. The crumbling T&H Dam will be removed.
In early 2026, the final design process for Phase I will begin, lasting about 12 months, after which 3-4 years of construction is expected.
Community input and independent technical review are critical throughout the planning, final design, and construction process to ensure that pollutants are properly removed.
It’s also critical that the bed and banks of the cleaned River be designed to serve as habitat for fish and wildlife, and as a vibrant recreational resource for the entire community.
Phase II is the 2.7 miles from the T&H Dam to Lower Mills. It includes Hyde Park, Mattapan, Dorchester, and Milton. It is much less contaminated.
Studies of this area are underway, and many key decisions remain, such as what the future of the Baker Dam will be and how much material will be removed from the River.
The goal is to have studies and design work for Phase II completed so that the Phase II construction can begin as soon as Phase I is finished.
For more information, email NepRWA Greenways Director, Andres Ripley, at ripley@neponset.org

What is “Superfund?”
Superfund is the federal program that helps clean up major pollution sites across the US. It is run by the U.S. Environmental Protection Agency (EPA), and it tackles the most challenging sites.
What’s the Problem?
The Lower Neponset was home to many industrial facilities that discharged to Mother Brook or the Neponset. Learn more about the Neponset’s Industrial past.
Studies to restore herring and shad runs blocked by state-owned dams discovered river-bottom sediments contaminated with polychlorinated biphenyls (PCBs) and other industrial chemicals. After years of advocacy, the Lower Neponset became a Superfund site in 2022.
Not a “Local” Issue
Freshwater fish from the Lower Neponset roam as far upstream as Walpole and, via tributaries, to many communities, making fish unsafe to eat and impacting stream health miles away.
The Superfund cleanup will also clear the way for restoring herring and shad runs to most of the Watershed, helping to revive the entire Neponset River ecosystem.
Background
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, as well as opportunities for public input, the possible implementation of initial cleanup actions in certain areas, and the eventual implementation of comprehensive cleanup efforts.
NepRWA has advocated for the cleanup of this section of the River for over 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.







