Neponset River from Hyde Park to Dorchester could become federal Superfund site

The State House News Service reports the federal EPA yesterday formally proposed making the Neponset River, from Dana Avenue in Hyde Park to Dorchester Lower Mills a designated Superfund hazardous-waste and cleanup site due to the large volume of PCBs in river silt and the difficulties of trying to recoup costs from dozens of sites responsible for the contamination on one of the nation's oldest industrial waterways.

In its proposal to designate the lower Neponset, the EPA says:

Historically, numerous mills were established along the Lower Neponset River in the towns of Dorchester, Milton, Hyde Park, and Mattapan, utilizing dams to generate power initially to turn mill grinding wheels and later to operate the large industrial mills. ...

Nearly 60,000 cubic yards of PCB-contaminated sediments reside along the Lower Neponset River, behind the dams, in the Braided Channel area and near the confluence of Mother Brook. The contamination threatens the groundwater which is a potential source of public drinking water for more than 40,000 people within four miles of the site. The Neponset River is a fishery. Although the state has issued a fish advisory due to the presence of PCBs and dichlorodiphenyltrichloroethane (DDT), there is evidence that fishing and human consumption is still taking place. The state has also classified this portion of the river as impaired for recreational use due to the presence of PCBs, Escherichia Coli (E. Coli), and Enterococcus.

One source of contaminants in the Neponset used to be the Mother Brook - the oldest canal in the US, dating to 1639 - which joins the Neponset just before Dana Avenue in Hyde Park. But in 2006 and 2007, the state shut the brook, which starts at a dam on the Charles River in Dedham, and removed contaminated sediment. The work wasn't fully completed until 2009.

The state's efforts to get landowners to pay for at least some of the work on the relatively short brook illustrates the potential issues the EPA could face in assessing and collecting payment for work along the Neponset: It took some nine years of legal action in federal court to determine just which of present-day landowners were responsible for which percentage of pollution in the brook, part of which involved tracing the industrial histories for properties that were long since converted to other uses, including a supermarket and a charter school.