MWRA must report on the quality of the treated wastewater, or effluent, being discharged to Massachusetts Bay from the Deer Island Treatment Plant. Our discharge permit also requires us to monitor the ecosystem of Massachusetts Bay and Boston Harbor, measuring the health of fish and shellfish, as well as nutrients, pathogens, metals, and toxicity. See our pamphlet on Environmental Monitoring for more information.

MASSACHUSETTS BAY WATER QUALITY

Contingency Plan threshold exceedance (PDF)

Outfall Monitoring Overview

Proposed final modifications to the permit-attached Ambient Monitoring Plan

Massachusetts Bay page

Bacteria Monitoring near the bay outfall

Ambient monitoring quarterly (PDF)

Contingency Plan thresholds compared with ambient data (PDF)

Boston Harbor water quality

Environmental monitoring data

Boston Harbor beach data and fact sheets

Fish & shellfish in Boston Harbor & Mass. Bay

Winter flounder in the Harbor and Bay

Discharge Monitoring Reports for the Treatment Plant and CSO facilities (PDF)

Contingency Plan thresholds compared with effluent monitoring data (PDF)

Infiltration and Inflow report (PDF)

Demand Management, Flow Limitation (PDF)

Deer Island Treatment Plant monthly performance (PDF)

Treatment Plant annual maintenance (PDF)