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Boston Harbor and Massachusetts Bay
MWRA Environmental Quality Department

Contingency Plan

MWRA developed a Contingency Plan to ensure that discharge from the Bay outfall does not result in adverse impacts. The Plan identifies thresholds that can suggest that effluent quality or conditions in the Bay may be changing. When monitoring indicates that "Caution" or "Warning" threshold levels for certain environmental indicators are exceeded, these exceedance reports must be posted on this website.

Download Contingency Plan (PDF)

Contingency Plan Reports:

Contingency Plan Exceedance Reports

Contingency Plan Quarterly Report on Ambient Monitoring
Data on mussel contamination, dissolved oxygen, and algae at sampling locations in Massachusetts Bay, compared with threshold limits in the Contingency Plan.

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) compared with threshold limits in the Contingency Plan.

Outfall Monitoring Overview 
The annual outfall monitoring overview presents monitoring program results for effluent and field data from the previous year. All results are compared to Contingency Plan thresholds.

Proposed Modifications to the Contingency Plan (November 2001)
Proposed Contingency Plan threshold modifications to dissolved oxygen concentration, dissolved oxygen saturation, and Alexandrium abundance.
(See previous modification request)

Outfall Contingency Simulation: Treatment Plant Chlorination Upset and Red Tide  
Simulates the notification and decision-making processes that would occur in the event of unexpected problems at the treatment facility or in Massachusetts Bay.