EPA designates Lower Neponset River in Boston and Milton a Superfund site

The U.S. Environmental Protection Agency on Monday designated the Lower Neponset River, which runs through Milton, Dorchester, Mattapan and Hyde Park, a federal Superfund site for environmental clean-up.

The 3.7-mile stretch is now on the National Priorities List, a catalog of sites considered the most hazardous and uncontrolled contaminated areas in the country.

"It's time," said David Cash, regional administrator for EPA Region 1. "We now have a mechanism to address the contamination in the sediment that has plagued the river for decades."

According to the EPA and the Massachusetts Department of Environmental Protection, the Lower Neponset River is polluted with chemicals called polychlorinated biphenyls, or PCBs. These contaminants have been linked to several health hazards, including reproductive and neurological problems.

PCBs bind to organic material and are found in the river's sediment. They've been identified in particularly high concentrations at the Tileston and Hollingsworth Dam in Hyde Park and the Baker Dam in Milton/Lower Mills. This means the river is relatively safe for recreation like boating, but people are warned against eating any fish caught in the river, as well as extended contact with the river bed.

The Superfund designation launches a federal investigation into the site. Some parts of that investigation are already underway, according to the EPA.

"We are working on getting contractors, we're scoping the work, so it has started," said Meghan Cassidy, deputy director of the EPA Superfund Program in Region 1. She said the process of taking and analyzing samples is likely to take place next spring.

The PCB pollution is attributed to former industrial activity in the area dating back to the 1930s, according to the MassDEP. The federal investigation will seek to link the chemicals to specific companies and take a deeper look at the range and risk of contamination in the area. Federal authorities will then develop a plan to clean up the pollution using federal resources and expertise.

Administrator Cash said the EPA intends to move the process along as quickly as possible, but it will still take years to complete. At the event marking the designation, Sen. Elizabeth Warren, Congresswoman Ayanna Pressley and Congressman Stephen Lynch committed to getting the federal funding for the cleanup to Massachusetts as soon as possible.

The Lower Neponset River was added to the National Priorities List after decades of advocacy and local cleanup efforts by community groups. EPA officials said community involvement will continue to be a critical part of the cleanup process.

"The best collaborations are those which are community driven and government endorsed," said Pressley, who represents the district part of the site is in.

"We want the community to be totally engaged in this process from day one, we want them to know what is going on with each step of this process," said Vivien Morris, a neighborhood resident, advocate and chairperson of the Edgewater Neighborhood Association. "We are very committed to this river."

The first federal evaluations of this stretch of the Neponset River took place in 2002. In 2015, MassDEP requested the EPA evaluate the river for Superfund status due to elevated levels of PCBs. Last year, Gov. Charlie Baker sent a letter to the EPA backing the designation, saying the site deserved to be included due to the "serious nature of the contamination."

The EPA proposed adding the site to the National Priorities List in September 2021. That proposal started a public comment period. Monday's decision included a review of those comments, nearly all of which voiced support for the designation.

In addition to the Lower Neponset River, Massachusetts has 31 other Superfund sites, according to the EPA.