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Boston Harbor and Massachusetts Bay

Massachusetts Water Resources Authority

Effluent Monitoring

MWRA monitors the effluent, or treated sewage, that is discharged from the Deer Island Treatment Plant (DITP) into Massachusetts Bay, to ensure that it meets the standards set out in the NPDES discharge permit. DITP received the Platinum 8 award from the National Association of Clean Water Agencies, because its effluent quality has met all permit limits for eight consecutive years.

Effluent solids 1990-present
Solids discharges from MWRA's Deer Island Treatment Plant (DITP) have fallen and remained low since the beginning of the Boston Harbor Project. Discharges of sludge (sewage solids) to Boston Harbor ended in 1991. Improved, secondary treatment began at DITP in 1997, resulting in an 80% decrease in solids discharges by 2000.
Decreasing effluent solids also reduced the discharge of toxic metals, as metals attach to solids in wastewater. In addition, MWRA increased its enforcement of industries that are required to pre-treat their wastewater, preventing metals and other pollutants from entering the sewage system.

Effluent Monitoring Reports (PDF):

Monthly discharge monitoring results from Deer Island Treatment Plant and Combined Sewer Overflow treatment facilities are summarized in tables submitted to federal and state regulators.

Plant Performance Data
Monthly data on the Deer Island Treatment Plant's effluent discharges. Measurements of fecal coliform bacteria, suspended solids, oxygen depleting materials, and chlorine residual are included.

Contingency Plan Quarterly Report on Effluent Monitoring
Summary of data on pH, fecal coliform, toxicity, oil and grease, and nitrogen in Deer Island Treatment Plant effluent (treated wastewater) that is discharged into Massachusetts Bay.