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Boston Harbor and Massachusetts Bay
MWRA Environmental Quality Department

The Massachusetts Water Resources Authority has been granted a federal National Pollutant Discharge Elimination System (NPDES) permit to discharge effluent from the Deer Island Wastewater Treatment Plant into Massachusetts Bay. MWRA is required by the permit to post water quality reports on-line.

Use the drop-down menu to view reports
required by MWRA's discharge permit.

What's New Links to recent MWRA treatment plant performance and environmental quality reports.
Ambient Monitoring Reports on monitoring in Massachusetts Bay.
Best Management Practices To keep each facility's operation clean so it does not become a polluter.

Contingency Plan

MWRA developed this plan to ensure that discharge from the outfall does not result in adverse impacts to the Bay. The Plan identifies thresholds that can suggest that effluent quality or conditions in the Bay may be changing.
Contingency Plan Exceedance Reports "Caution" or "Warning" level exceedances of Contingency Plan thresholds for water quality monitoring in Massachusetts Bay. Designed to detect potential effects of the outfall.
Discharge Monitoring Reports on the quality of effluent being discharged into Massachusetts Bay.
CSO Variance: MWRA has been granted a variance from having to meet water quality standards in the Charles River and Alewife Brook/Upper Mystic River. MWRA is implementing a plan to reduce the impacts of combined sewer overflows.
Flow Limitation Demand management and water conservation efforts designed to minimize flows to the Deer Island Treatment Plant.
Groundwater Remediation MWRA prohibits discharges into the MWRA system for groundwater remediation activities. The NPDES permit requires an annual review of this policy.

Local Limits

A review of MWRA standards and limits for discharges from certain business or industrial sewer users.

Operations & Maintenance

Status reports on routine maintenance of the sewer system, the sewage treatment plant, and the sludge pelletizing plant; and a report on steps taken to reduce leakage into MWRA's pipes. Notifications about operational incidents or upsets.
Outfall Monitoring Science Advisory Panel (OMSAP) Presentations made to OMSAP, who advises the US Environmental Protection Agency and the Massachusetts Department of Environmental Protection on scientific and technical matters related to MWRA's bay outfall and any potential impacts of the discharge on its receiving waters.

Pollution Prevention

MWRA's industrial pre-treatment and household education programs.
Prior Notice Notice of any significant change in the pollutants being introduced into the treatment plant by, for example, a new industry. 
Archive Older reports are available to those who want historical information.

MWRA makes available to the public copies of all NPDES required reports at Hyannis Public Library and at the MWRA library, 100 First Ave., Charlestown Navy Yard, Boston, MA 02129.

Many of our reports are in PDF format, which requires Adobe Acrobat Reader®, a free program available from Adobe Systems. To request a paper copy of any report, please contact the MWRA Environmental Quality Department at 617-788-4601, or e-mail us at