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Boston Harbor and Massachusetts Bay
Massachusetts Water Resources Authority

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 Contingency Plan Exceedance Reports are posted on this website.

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
Proposed Contingency Plan threshold modifications, most recently to delete the Caution Level threshold for Phaeocystis; and delete the upper range thresholds for infaunal diversity.

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.

Contingency Plan Exceedance Reports





Questions? Email the Environmental Quality Department