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Boston Harbor and Massachusetts Bay
Massachusetts Water Resources Authority

MWRA Environmental Monitoring

Boston Harbor & Rivers
The Massachusetts Water Resources Authority's (MWRA) has been monitoring water quality in Boston Harbor and its tributary rivers since 1989.

Harbor Beaches
Water quality at Wollaston, Carson, Constitution, Tenean and Pleasure Bay beaches is tested by the Department of Conservation and Recreation (DCR) with assistance from the Massachusetts Water Resources Authority. More information on these beaches is available on the Boston Harbor Beaches page.

Massachusetts Bay
The Bay bacteria monitoring program measures water quality from stations near the outfall, to stations as far as Cape Cod Bay. "Nearfield" stations are located within seven kilometers (4.3 miles) of the outfall diffuser. "Farfield" stations include all stations in Boston Harbor; the coastal, offshore, and northern boundary regions; and Cape Cod Bay.

The Ambient Monitoring Program addresses most Bay & outfall monitoring, and, except for the bacteria monitoring, is conducted by a contractor.

Effluent Monitoring

MWRA monitors the effluent (treated sewage) that is discharged into Massachusetts Bay, to ensure that it meets the standards set out in the NPDES permit. More information on the Discharge Monitoring page.

CSO Monitoring

The Combined Sewer Overflow (CSO) monitoring area includes the "receiving waters" of all CSO communities in greater Boston including the Inner Harbor, Boston Harbor embayments, and tributary rivers. Measurements include bacteria, nutrients, dissolved oxygen, and water clarity.

Technical Reports

Summaries and technical analysis of MWRA water quality monitoring in Boston Harbor and Massachusetts Bay are available for download on our Technical Reports List.