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Boston Harbor and Massachusetts Bay
Massachusetts Water Resources Authority


Massachusetts Bay

The Massachusetts Water Resources Authority has monitored the Bay's water quality since 1992, as part of a carefully designed Ambient Monitoring Program.  MWRA discharges treated sewage effluent through a 9.5-mile outfall into Massachusetts Bay. Monitoring results have shown that while MWRA's effluent quality has improved, animal communities in the Bay continue to thrive. Images from this outfall reflect a healthy, vibrant ecosystem.

Images from the outfall in 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.

Latest Bay bacteria data  
About the Mass. Bay outfall  
Changes after the Mass. Bay outfall  

Monitoring Results

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.

Bay Water Quality Data

Bay water quality is continually measured using a buoy off Cape Ann run by the Northeastern Regional Association of Coastal and Ocean Observing Systems (NERACOOS). See buoy data on NERACOOS website.
Photograph of data collection buoy in 
			  Massachusetts Bay