MWRA home

Massachusetts Bay

Since 1992, the Massachusetts Water Resources Authority has monitored the Bay's water quality as part of its 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.

The annual Outfall Monitoring Overview contains monitoring data from Massachusetts Bay. Over the years, monitoring has revealed that:


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).

Photograph of data collection buoy in 
			  Massachusetts Bay

See buoy data on NERACOOS website.