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Boston Harbor and Massachusetts Bay
Massachusetts Water Resources Authority


Contingency Plan Modifications

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.

Under MWRA's NPDES discharge permit, Contingency Plan interim modifications can be made at any time and do not require a modification to the permit. The Contingency Plan was intended to be a living document, with a modification process outlined by the U.S. Environmental Protection Agency.

February 15, 2018: Final 2017 Contingency Plan threshold modifications

January 3, 2017: Proposed modifications to Phaeocystis and infaunal diversity thresholds

November 15, 2001: Proposed modifications to dissolved oxygen and Alexandrium thresholds <





Questions? Email the Environmental Quality Department