Boston Harbour goes sewage-free

Daily discharges of hundreds of millions of gallons of treated effluent into the shallow waters of Boston Harbour are ending, says Greater Boston’s wastewater utility, Massachusetts Water Resources Authority (MWRA).


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A new $390 million outfall discharging treated wastewater to deep waters outside the harbour is the latest major milestone in MWRA’s programme of a decade of improvements to Boston Harbour, according to the Authority. MWRA also recently completed new facilities for secondary sewage treatment at its Deer Island Treatment Plant.

“With the new outfall, there will be a dramatic change,” said MWRA Executive Director Douglas B MacDonald. “Wastewater discharges to Boston Harbour will end. All the improvements to date around the outfall location will accelerate as the natural clarity and cleanliness of the water is established. Water conditions should also improve throughout the areas of Massachusetts Bay affected by tidal interchanges of water with Boston Harbour, the Bay’s largest estuary.”

Scientists monitoring the harbour since 1992 have already documented cleaner water and healthier ecosystems due to the water authority’s improvements, according to MWRA. The programme started in 1991 with the ending of direct discharges of sewage sludge, and the dramatic improvements since then should continue, says MWRA. As soon as the new outfall is turned on, the effluent plume now visible on the water surface near the obsolete outfalls will disappear, and increases in water clarity should be seen within hours.

The outfall is subject to an Environmental Protection Agency (EPA) permit, resulting from years of citizens input. The outfall has some of the most restrictive conditions ever imposed on a metropolitan area’s sewage discharges, says MWRA. The new outfall diffuser is 6,600 feet (over 2000 metres) long, and is made up of hundreds of small discharge ports to assure effective dispersal and dilution of the wastewater stream.

Data collection, monitoring, research and modelling has been performed to predict the impact on Massachusetts Bay from discharges at the new outfall site.

“The science programme prompted by the outfall project has created unique research opportunities and led to important scientific and public policy results,” said Dr Andrea Rex, an MWRA microbiologist. “Massachusetts Bay and Boston Harbour have become one of the best-studied and best-understood marine environments in the world. Fish veterinarians, plankton biologists, physical oceanographers and benthic ecologists, just to name a few, have shared their insights not only for the benefit of basic science, but to assure that critical environmental policy questions have been soundly addressed. Not only MWRA’s customers and ratepayers, but US EPA and the National Marine Fisheries Service, have benefited from these efforts.”

Over recent years, studies have documented many environmental gains to the harbour, says MWRA. There has been a dramatic decline in the incidence of liver tumours in flounder, and the make-up of benthic communities has moved from pollution tolerant capitellid polychaetes to tube-building amphipods, which in turn appear to be in the process of being replaced by more diverse communities, says MWRA. Mussels placed near the old outfalls are also accumulating lower levels of organic pollutants, and some investigators are predicting that seagrass beds may return to wide areas of the harbour.

“This is a major step in our effort to clean up Boston Harbour and to provide the first class recreational opportunities for our citizens and unpolluted habitat for our wildlife,” said Bob Durand, Secretary of Environmental Affairs. “It’s important to recognise how this project improves the quality of life for all of us.”

A new $390 million outfall discharging treated wastewater to deep waters outside the harbour is the latest major milestone in MWRA’s programme of a decade of improvements to Boston Harbour, according to the Authority. MWRA also recently completed new facilities for secondary sewage treatment at its Deer Island Treatment Plant.

“With the new outfall, there will be a dramatic change,” said MWRA Executive Director Douglas B MacDonald. “Wastewater discharges to Boston Harbour will end. All the improvements to date around the outfall location will accelerate as the natural clarity and cleanliness of the water is established. Water conditions should also improve throughout the areas of Massachusetts Bay affected by tidal interchanges of water with Boston Harbour, the Bay’s largest estuary.”

Scientists monitoring the harbour since 1992 have already documented cleaner water and healthier ecosystems due to the water authority’s improvements, according to MWRA. The programme started in 1991 with the ending of direct discharges of sewage sludge, and the dramatic improvements since then should continue, says MWRA. As soon as the new outfall is turned on, the effluent plume now visible on the water surface near the obsolete outfalls will disappear, and increases in water clarity should be seen within hours.

The outfall is subject to an Environmental Protection Agency (EPA) permit, resulting from years of citizens input. The outfall has some of the most restrictive conditions ever imposed on a metropolitan area’s sewage discharges, says MWRA. The new outfall diffuser is 6,600 feet (over 2000 metres) long, and is made up of hundreds of small discharge ports to assure effective dispersal and dilution of the wastewater stream.

Data collection, monitoring, research and modelling has been performed to predict the impact on Massachusetts Bay from discharges at the new outfall site.

“The science programme prompted by the outfall project has created unique research opportunities and led to important scientific and public policy results,” said Dr Andrea Rex, an MWRA microbiologist. “Massachusetts Bay and Boston Harbour have become one of the best-studied and best-understood marine environments in the world. Fish veterinarians, plankton biologists, physical oceanographers and benthic ecologists, just to name a few, have shared their insights not only for the benefit of basic science, but to assure that critical environmental policy questions have been soundly addressed. Not only MWRA’s customers and ratepayers, but US EPA and the National Marine Fisheries Service, have benefited from these efforts.”

Over recent years, studies have documented many environmental gains to the harbour, says MWRA. There has been a dramatic decline in the incidence of liver tumours in flounder, and the make-up of benthic communities has moved from pollution tolerant capitellid polychaetes to tube-building amphipods, which in turn appear to be in the process of being replaced by more diverse communities, says MWRA. Mussels placed near the old outfalls are also accumulating lower levels of organic pollutants, and some investigators are predicting that seagrass beds may return to wide areas of the harbour.

“This is a major step in our effort to clean up Boston Harbour and to provide the first class recreational opportunities for our citizens and unpolluted habitat for our wildlife,” said Bob Durand, Secretary of Environmental Affairs. “It’s important to recognise how this project improves the quality of life for all of us.”

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