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Boston Harbor and Massachusetts Bay
Massachusetts Water Resources Authority


Massachusetts Bay

In September 2000, the Massachusetts Water Resources Authority (MWRA) officially opened the Massachusetts Bay outfall and stopped discharging treated wastewater (effluent) to Boston Harbor. The results shown by years of monitoring are a cleaner Harbor and a healthy Bay.

MWRA has monitored the Bay's water quality since 1992, as part of a carefully designed Ambient Monitoring Program.  We have found that while effluent quality has improved, animal communities in the Bay continue to thrive. Images from the outfall reflect a healthy, vibrant ecosystem.

MWRA monitors bacteria around the MWRA outfall and elsewhere in Massachusetts Bay.
See the results of MWRA's bacteria monitoring near the Mass. Bay outfall.

Also receiving a clean bill of health are Cape Cod Bay and Stellwagen Bank National Marine Sanctuary, a feeding ground for the right whale. Detailed results are available in the annual Outfall Monitoring Overview.

2019 Outfall Monitoring Overview
Instruments on the NERACOOS buoy off Cape Ann measure temperature, salinity, chlorophyll, and oxygen.  The Outfall Monitoring Overview summarizes environmental data from the Harbor and Bay.



Updated May 10, 2021