The Baker Dam in Lower Mills is one of two dams on the Neponset River in Boston. Environmental advocates want the dam removed to facilitate fish migration. New studies due out this month will also point to the dam's role in trapping sediments that contain PCBs, remnants of industrial waste dumped into the river decades ago.
Reporter file photo

By Bill Forry
Managing Editor

Two scientific studies of the Neponset River that will be made public in the next month indicate that the remnants of old industrial waste - long known to be trapped behind two existing dams on the Boston end of the river - are still periodically released into the river, contaminating sections of the waterway and the marine life that live in it. Sources familiar with the data in the reports, which will be detailed at a community meeting in Lower Mills on December 13, say that they will confirm what most local environmental advocates have long believed: that the river and the fish that swim in it are adversely impacted by decades-old pollutants that are disturbed and released into the water, particularly during and after major storm events.

The Neponset River Watershed Association (NepRWA), a leading force in restoration efforts along the river in recent years, is already discussing details of the forthcoming reports at civic association meetings in Dorchester and Mattapan. The group gave a presentation on the issue at Tuesday's meeting of the Cedar Grove Civic Association and plans to organize a community advisory group in the coming weeks to take action based on the recommendations in the reports.

"I think what's new here is the realization of the full extent of the PCB problem," said Ian Cooke, director of the Neponset River Watershed Association. "We definitely have a PCB hot spot in Hyde Park and a significant problem in Lower Mills. It's not anything we would have hoped for, but when we tell people there's a problem with contamination, they are not surprised."

According to NepRWA staff, preliminary results from testing done over the last year-and-a-half indicate that an average of 25 pounds of PCBs - otherwise known as Polychlorinated Biphenyls - are being released into the river and estuary each year from sediments caught behind the Baker Dam in Lower Mills. A similar problem is also releasing PCBs into the river from the Tileston-Hollingsworth dam in Hyde Park, site of a former paper mill. The chemical remnants, which are embedded in sediments that have built up behind the dam over many years, are typically released when storm events stir up the mud and muck that have trapped the pollutants.

The first of the two reports expected to be released at the December meeting is a study by Rob Brault, a scientist who works for the United States Geological Survey (USGS). Brault's report, now in draft form, details the level of PCB contamination in the river and the estuary and will show, according to sources familiar with his work, that the pollutants are slowly migrating into the estuary. Brault's analysis could also help the state's Department of Environmental Protection (DEP) in their ongoing work to identify the likely source of the PCBs in the Neponset.

The second report, conducted by Malone & McBroom, a private firm hired by the state's Riverways program, will include detailed analysis of how the state might go about resolving the dam problem. That report will include preferred alternatives, which may include removing or partially removing both the Baker Dam in Lower Mills and the Tileston-Hollingsworth dam in Hyde Park. It will also outline how the state might clean-up sediments that are contaminated.

Tim Purinton, a river restoration planner for the state's Riverways program, expects that the reports will be pivotal in giving the government and activists hard evidence of a long-suspected problem and a roadmap on how to begin fixing it.

"We know sediments behind the dams are contaminated," Purinton said. "This allows us to pull back and get the big picture. We don't have results in hand yet, but the December meeting will give us a new window."

Steve Pearlman, advocacy director for NepRWA, said that an "accident" at the Baker Dam in Lower Mills last spring is thought to have caused the release of an unusually large segment of contaminated sediment into the estuary. A temporary part of the dam - made up of wooden boards held in place by steel beams - gave way during a storm, Pearlman said.

"A tremendous quantity of PCBs went over the dam during that event," Pearlman said.

PCBs - which are likely the result of industrial pollution into the river prior to the ban of certain chemical agents in the 1970s - could be harmful to humans who consume the fresh water fish that live and spawn in the Neponset. According to Cooke and others, testing of bottom feeding fish taken from the lower Neponset have shown PCB levels that are three times the levels considered safe.

"It is clear that resident fish between Lower Mills and upstream, fresh water fish, have PCBs three times the level considered safe," Cooke said. "People shouldn't be eating fish caught in that part of the river."

Fish that do not make the river or estuary their primary habitat - like salt water stripers and blue fish that enter the Neponset to feed - are not thought to be a danger, Cooke said. Recreational use of the Neponset for boating or canoeing - both of which have seen a marked increase as state land has been turned into recreational space along the river in the last 15 years - is also not a problem, Cooke said.

"We have no reservations about canoeing, but we do tell people to minimize contact with the mud," said Cooke.

"PCBs aren't uniformly everywhere in the river or estuary. They attach themselves to fine organic particles, which tend to be in the mucky areas. We tell people to take take sensible precautions to minimize their exposure."

Whether or not swimming in the river is a sensible idea is a matter of some debate. The DEP rates it unsafe.

"Swimming in the river is questionable," said Steve Pearlman. "If you swam, and it hadn't rained recently, you'd be fine. In a big storm, the sediments get stirred up and dissolve into the water."

Chris Pyatt, an environmental analyst for the DEP, says that Brault's report could give him some important information on the original source of the contamination.

"We're working to track that back to the responsible parties," said Pyatt, who said that Brault's will include a sort of PCB "fingerprinting" that may lead to a specific industrial source along the river.

Connecting the PCBs to a decades-old industry on the river could prove critical to an eventual clean-up effort. Presently, a $3 million remediation effort is underway at Mother's Brook in Hyde Park. In that case, the Thomas and Betts company, the present owner of an old electrical manufacturing site that polluted the brook with PCBs decades ago, is paying for the clean up, which includes the excavation of the top foot-and-a-half of soil and sediment along the riverside, an area that covers some 1500 feet of property. Pyatt says that state law requires that present-day owners of PCB source sites to pay for the remediation efforts.

In the case of the Neponset itself, Pyatt says that there is no known source of the PCBs yet. Pyatt will carefully study Brault's findings for any solid leads.

The DEP is also preparing to begin a new round of soil testing along the banks of the river, where past dredging efforts may have left contaminants exposed. Pyatt says that an earlier public meeting will likely be held in late November to brief residents about that process.

"We will look at where there are pathways and canoe launches as part of a due diligence sampling to analyze these areas to see if they contain PCBs," said Pyatt. The samplings will be done by three-person crews with soil loggers, Pyatt said.

Meanwhile, Ian Cooke hopes that the forthcoming reports will trigger a new urgency from officials and the community to resolve the PCB contamination issue before it is allowed to further spread. Ultimately, that resolution is tied directly to the fate of the two dams. Neponset River Watershed Association has long called for the removal of the dams, a position that Cooke believes will be enhanced by the report. NepRWA has begun making presentations to local civic groups in Mattapan and Dorchester in hopes of fielding volunteers to serve on a community advisory group that Cooke said will give some oversight to what should happen next. That group, Cooke said, should start meeting in January.

"We're really keen to get people together and build consensus about what people want to do, instead of sitting back and waiting 20 years for things to sort themselves out," Cooke said. "We've taken the initiative to hire some facilitation folks to come out and do a more in depth discussion of this for folks who want to send more than one night thinking about it.

"In order for anything to get done there will need to be significant amount of agreement and support on how we should proceed," said Cooke.

A venue has not yet been solidified for the Dec. 13 meeting in Lower Mills. For more information on that, call Gabrielle Stebbins at the state's Riverways office at 617-626.1571.

For more Reporter coverage on the Neponset River and Dorchester's waterfront, click here.