MWRA's NPDES discharge permit for the Deer Island Wastewater Treatment Plant requires extensive monitoring and reporting.
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.
The Bay bacteria monitoring program, which measures water quality near the outfall to ensure that there is no risk to shellfish consumers.
The Ambient Monitoring Program addresses most Bay & outfall monitoring, as outlined in MWRA's Ambient Monitoring Plan.
Harbor & Rivers
The Massachusetts Water Resources Authority's (MWRA) has
been monitoring water quality in Boston Harbor and its tributaries since
1989. MWRA makes at least 20 visits
to each sampling location every year.
Monitoring areas are: Charles River,
Mystic River/Alewife Brook, Inner Harbor, Northern Dorchester Bay/Carson
Beach, Southern Dorchester Bay/Tenean Beach, Neponset River, and Quincy Bay/Wollaston
Water quality at Wollaston, Carson, Constitution, Tenean and Pleasure Bay beaches is tested by the Department of Conservation
and Recreation (DCR) with assistance from MWRA.
Questions? Contact the Environmental Quality Department
Combined Sewer Overflows
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.
See map with sampling and CSO locations
along the shoreline into streams, rivers, and estuarine areas.
To allow for an intensive study of each affected body of water, receiving
waters were divided into distinct geographic areas based on locations
of tributaries and proximity to CSOs. Each area was monitored on a rotating
schedule, with all areas sampled equally.
More information on CSOs
Long-term Harbor monitoring helps in identifying
change in water quality over time. Historical results from 1989 to last year for bacteria, nutrients, and other
water quality parameters are available for download in Excel spreadsheets
for Boston Harbor and three tributary rivers.
Data Analysis & Interpretation
Summaries and technical analysis of MWRA water quality monitoring in Boston Harbor and Massachusetts Bay are available for download on our Technical Reports List.