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Boston Harbor and Massachusetts Bay
MWRA Environmental Quality

Massachusetts Bay

Photograph of data collection buoy in 
			  Massachusetts Bay
Instruments attached to a buoy near the Mass. Bay outfall (shown) provide MWRA with continuous water quality information.
(Photo: National Data Buoy Center)

Mass. Bay bacteria data
UMass Dartmouth Bay modeling Useful Links
Literature List
Technical report on ambient water quality
The Massachusetts Water Resources Authority has been monitoring Massachusetts Bay since 1992. This Ambient Monitoring Program was intended to measure the effects of stopping the discharges of sewage effluent to Boston Harbor and instead moving the better-treated effluent into the deeper waters of Massachusetts Bay. 

Monitoring has enabled MWRA to better understand the natural variability in the Bay's water quality. Data has shown that the water near the outfall and throughout the bays is heavily influence by river inflows, weather, and other factors. At stations mostly near the outfall, studies focus on the effluent, water column, sea floor, and fish and shellfish. There are also monitoring stations as far out as Cape Cod Bay.

Monitoring results have been consistent with predictions of no unanticipated effects to the Bay associated with the outfall discharge. MWRA's- effluent quality has improved, and animal communities in the Bay continue to thrive.

Buoy collecting hourly data off Cape Ann Link to instrument location near Stellwagen Bank Link to Outfall instrument location

Bay water quality is measured using buoys at two locations (click to see data):

Cape Ann locationOff Cape Ann near Stellwagen Bank, and

Outfall location Near the MWRA outfall.

The annual Outfall Monitoring Overview contains monitoring data from Massachusetts Bay. Over the years, monitoring has revealed that:
The quality of the effluent (treated wastewater) has improved, due to better control of pollution sources.
Chlorophyll, plankton, and dissolved oxygen levels are normal.
Sediments near the outfall show healthy, normal communities.

There are some detectable effects of the discharge near the outfall, such as increased ammonium. Dissolved oxygen levels in bottom waters near the outfall have not changed and remain within state water quality guidelines.

MWRA's goals for Boston Harbor and Massachusetts Bay are based on concerns expressed by the public. These goals include clean beaches, healthy marine resources, seafood safe for eating, and protecting the natural beauty of the Harbor and the Bay.