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The Neponset River Restoration Project focuses on a 5-mile stretch of the Neponset River known as the “Lower Neponset,” in Milton, Hyde Park, Mattapan and Dorchester (project area). The Baker Dam is located in Dorchester/Milton Lower Mills, just upstream of Adams Street. The Tileston and Hollingsworth (“T&H”) Dam is located between Milton (off Truman Parkway) and Hyde Park (near River Street) and is not visible from any public streets.

Both dams are owned by the state and were built in the mid-1960s as part of a project that channelized the Lower Neponset, filled its floodplain, and removed three other dams that were severely damaged during the 1955 hurricane and flood. Historically, there were a series of mill dams built in the vicinity of the Baker Dam and the T&H Dam for industrial purposes, dating as far back as 1634.

The Baker and T&H Dams have no fish passage facilities and block a number of migratory fish species—most notably Blueback herring and American shad—from reaching 17 miles of historic spawning grounds on the Neponset River and its tributaries upstream. If the fish could bypass the dams, fish “runs” would be restored in Walpole, Norwood, Westwood, Dedham, Hyde Park, Mattapan, Dorchester, Quincy, Milton, and Canton. Prospective restored fish runs.

Government PCB Studies of Lower Neponset

In 1996, the Massachusetts Executive Office of Environmental Affairs entered a cooperative agreement with the US Army Corps of Engineers to evaluate options for restoring fish runs on the Neponset River. The EOEA designated the Riverways Program within the Mass Department of Fish and Game as the lead agency to coordinate and administer studies of the lower Neponset.

During the course of the study, it became apparent that river-bottom sediments in the Lower Neponset are seriously contaminated with toxic PCBs. The Riverways Program recruited the assistance of the US Geological Survey to complete detailed assessments of the extent, severity and possible sources of PCB contamination on the Lower Neponset River. Results on the PCB contamination have been published. At a January 2008 Public Meeting in Dorchester, a USGS scientist reported that:

·     Most PCBs were found in the sediments behind T&H Dam in Milton/Hyde Park and, to a lesser extent, behind Baker Dam in Lower Mills.

·     PCBs in sediments behind dams were found to be highly unstable and to become suspended in the water column after storms.

·     PCBs were found in the flesh of freshwater fish at levels that pose a significant risk to human health (based on these findings the state Department of Public Health (DPH) has issued a health warning for certain types of fish caught between Walpole and Baker Dam. DPH spent the summer of 2008 testing additional fish species and tributaries of the Neponset River for possible health risks.

·     Storms regularly wash large quantities of PCBs over the dams and into the Neponset River Estuary. PCBs were found in the water column all the way to the mouth of the Neponset at Dorchester Bay.

·     PCBs were found in the flesh of saltwater fish, though not at levels which pose a risk to human health.

River Restoration and PCB Cleanup Alternatives Studies

The Riverways Program also financed two studies by the private consulting firm of Milone & MacBroom to identify the costs and benefits of all feasible options for river restoration, including PCB cleanup. The firm looked at 28 alternatives, including “do nothing,” fish ladders, removal or alteration of the dams, installation of rock ramps and bypass channels, and channel relocation in combination with various sediment management techniques. Most of the fish passage alternatives were found to be technically infeasible. Feasible PCB cleanup alternatives included dredging the contaminated sediments and shipping them out of state and permanently “capping” the sediments behind the two dams.

A broadly based Neponset River Restoration Technical Advisory Committee (composed of representatives from three federal agencies as well as numerous state and local government agencies and private organizations) recommended as their preferred alternative the removal of Baker and T&H Dams and the dredging and removal of contaminated sediments. Many Massachusetts environmental and watershed groups (including MassAudubon, Sierra Club, Conservation Law Foundation and the Charles River Watershed Association) also support full dam removal.

Neponset River Restoration Citizens Advisory Committee and other opportunities for public input.

Before a “preferred” river restoration option is selected by the state for permitting, community input is being sought on the best way to proceed. The Neponset River Watershed Association, along with the Boston Environment Department, the Milton Conservation Commission, the Mass Department of Conservation & Recreation, the Mass Department of Fish & Game, and the Lower Mills Merchants Association have convened a Citizens Advisory Committee or “CAC” to evaluate options for restoring the Neponset River.

There will also be plenty of opportunities for public comment once the project is proposed for review under the Massachusetts Environmental Protection Act (MEPA), and the many required permits are applied for. . If you would like your voice to be heard now, fill out our Questionnaire.  

June 2008

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