River Restore

Neponset River Restoration, Milton and Boston

Project Background

River Revitalization

In 1994, the Neponset River Watershed was selected as the pilot for the Massachusetts Watershed Initiative. This Initiative brought federal, state, and local officials together with watershed, civic, and neighborhood groups to complete comprehensive natural resource assessments, develop a basin-wide action plan, and implement on-the-ground projects to meet the plan’s five goals: water quality, water quantity, open space/greenways, government, and outreach/education.

As part of developing and implementing the basin-wide action plan for the Neponset River, the Massachusetts Department of Fish and Game’s Riverways Program worked in partnership with the Neponset River Watershed Association to form and support the efforts of seven subwatershed Stream Teams. These Stream Teams, located within the Hawes Brook, Traphole Brook, East Branch, Mother Brook, Pine Tree Brook subwatersheds and Neponset River mainstem (Mattapan/Milton and Estuary), conducted shoreline surveys of their local streams and developed action plans to reach short and long-term goals for protection of valued resources. Key to their success was the involvement of town officials and technical assistance from state and federal agencies to address problems such as dry-weather sewer flows and create opportunities for public access. Many of these groups identified fisheries restoration among their goals.

The Commonwealth of Massachusetts, the cities of Quincy and Boston, and Town of Milton have engaged in ongoing efforts to restore aquatic and wetland habitats as well as improve and increase public access and recreational opportunities along and on the lower Neponset River. The Massachusetts Department of Fish and Game has led efforts to restore anadromous fish and riparian habitat since 1995. On-the-ground restoration of salt marsh hydrology and habitat in the estuary began in 2004. Key parks and paths featured in the Massachusetts Department of Conservation and Recreation’s Master Plan for the Neponset River Greenway are completed or under construction in the estuary. Two Areas of Critical Environmental Concern, the Neponset River Estuary and Ponkapog Bog/Fowl Meadow, have been designated by the state in response to local nomination and support.

The restoration and revitalization of the lower Neponset River and its estuary has faced challenges common to urban watersheds, including constraints due to surrounding and abutting land uses and transportation corridors, changes in morphology due to dredging and channelization (much of which took place in the 1950s and 1960s for public purposes such as flood control and navigation), and compromised water quality due to dry weather sewer overflows (largely abated) and wet weather stormwater runoff. Today, neighborhoods, municipalities, community organizations, and state and federal agencies have a unique opportunity to come together and collaborate on restoring the river and river corridor in a broad and inclusive manner – restoring ecological function and historic fisheries, restoring public access and scenic vistas, creating recreational opportunities, and preserving historic buildings while creating residential development.

Fish Passage and Habitat Restoration

Once abundant in the lower Neponset River , the populations of two anadromous fish have dwindled and disappeared following the construction of mill dams, which obstructed upstream passage. Based on the quality and quantity of habitat observed by the Massachusetts Division of Marine Fisheries in a 1995 survey, they determined that the “ Neponset River be given a high priority for blueback herring restoration and American Shad development…” and these species have been stocked on a regular basis.

In order to obtain the technical information necessary to evaluate options for restoring upstream passage for blueback herring and American Shad, an ecological restoration study has been underway since 1998, managed by the U.S. Army Corps of Engineers pursuant to s. 206 of the Water Resources Development Act. This study was requested by then-Secretary of Environmental Affairs Trudy Coxe. The Massachusetts Department of Fish and Game acts as the non-federal sponsor, with the Riverways Program serving as liaison among agency and community stakeholders. A Preliminary Draft Environmental Restoration Report and Environmental Assessment, Neponset River Fish Passage and Habitat Restoration Project, including the Tileston and Hollingsworth Dam and the Walter Baker Dam, was completed by the U.S. Army Corps of Engineers in 2002. This Preliminary Report identified fishway, dam removal, dam breaching, and sluiceway modification alternatives at the Baker and Tilestone-Hollingsworth Dams that create opportunities for up- and down-stream passage of anadromous fish and varying levels of restored riparian and riverine habitat.

Remediation of Sediment Contamination

One of the findings of the Corps’ Preliminary Draft Report was the presence of polychlorinated biphenyls (PCBs) in the sediments impounded behind the Walter Baker and Tilestone-Hollingsworth Dams. The sampling effort was limited, however, to one sample in each impoundment.

In 2002 and 2003, the U.S. Geological Survey, working in cooperation with the Riverways Program, collected sediment-grab samples from the outlet of Fowl Meadow in Canton to the Walter Baker Dam in Milton, and sediment cores from the impoundments at the Walter Baker and Tileston and Hollingsworth Dams and from the impoundment of the former Jenkins Dam. These samples were analyzed for elements and organic compounds commonly found in rivers that drain historically industrial and urban watersheds, including polyaromatic hydrocarbons, organochlorine pesticides, and PCBs. In addition, PCB concentrations in the water column were measured by means of a passive water-sampling system (PISCES) and PCB concentrations in skinless fillets were measured in fish collected from each impoundment.

Although enriched compared to background concentrations, sediment quality in the Neponset River was found to be generally better than that of other urban rivers in the United States, except with respect to one constituent, polychlorinated biphenyls. Depositional areas within the river, particularly impounded and formerly impounded reaches of the river, are highly contaminated. PCB concentrations averaged about 140,000, 30,000, and 32,000 parts per billion (PPB) in cores from the Tileston and Hollingsworth impoundment, braided channel, and Walter Baker impoundment, respectively.

In 2005 and 2006, the U.S. Geological Survey will complete field surveys to determine the transport and fate of PCBs from the Neponset River to Boston Harbor and PCB concentrations in a larger sample of fish from the lower Neponset River . 

In response to the USGS findings, Riverways entered into partnership with the University of Massachusetts at Amherst to sponsor a technical session and workshop at the 2004 20th Annual International Conference on Soils, Sediments, and Water that engaged a select group of national academic and private leaders in an interactive exploration of available and emerging technologies and techniques for managing and remediating contaminated sediment. The sediment forum identified a range of potential solutions that involve in-situ treatment and confinement techniques in addition to dredging and disposal options. In 2005, Riverways is working with The Johnson Company, Inc. to research, verify, and outline a strategy for implementing selected traditional and innovative technologies and approaches to achieve ecological restoration and contaminant remediation, including potential pilot projects for further evaluation in the lower Neponset River .

Outreach and Public Participation

Throughout the ecological restoration and contaminant remediation studies, public education and outreach activities have accompanied technical, economic, and environmental analyses to provide information upon which to evaluate restoration alternatives. Community meetings on anadromous fish passage and ecological restoration have been held since 1997. In 1999 and 2001, Riverways hosted meetings for agency and community stakeholders to provide input to the scope of the Corps s. 206 study as well as respond to initial results and findings of the study.

In the spring of 2003, Riverways led and hosted a “conceptual rendering” process for community stakeholders to share technical aspects of fish passage and ecological restoration alternatives and elicit community feedback on uses and plans for the river. The skills of an engineer familiar with river geomorphology and restoration were combined with the artistic vision of a landscape architect to visually integrate scientific findings and historical and cultural values. Rendering techniques include photo simulations, which have the advantage of looking “realistic,” and hand-drawn illustrations, which allow the landscape architect to add features and show perspectives without being restricted to snapshots. The process served as a catalyst to stimulate public dialogue about how the restoration project could bring more people to the river and use it in positive ways. The process also identified an additional fish passage alternative, a partial breach and rock-ramp combination that had not been previously evaluated by the Corps s. 206 study.

In 2003, the Neponset River Watershed Association received a Riverways Small Grant to conduct interviews with community leaders and lead a series of information and education activities with community groups. Themes explored included the ecology of the Neponset, how human actions have modified the river, as well as fisheries and the current restoration effort.

The development of new data and information about the ecological health of the river offers a unique opportunity to work together with community groups at a critical step in the river’s recovery. In 2004, Riverways received funding from the Massachusetts Environmental Trust to implement the “Neponset River Environmental Literacy Project.” Working in collaboration with the University of Massachusetts at Amherst , this project will develop techniques for communicating environmental contaminants in the context of ecological restoration and build local capacity for community members to serve as presenters to share ecological restoration and environmental cleanup information and data with the community-at-large.