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Boston Harbor and Massachusetts Bay
Massachusetts Water Resources Authority

Contingency Plan Exceedances

MWRA's NPDES discharge permit requires MWRA to report Contingency Plan exceedances to regulatory agencies and the public. These notices are triggered by unusual results of effluent or ambient monitoring. Effluent monitoring takes place in the treatment plant, while ambient monitoring examines the environment surrounding the outfall in Massachusetts Bay.

Caution and Warning Level Exceedances

November 2016 - Phaeocystis (nuisance algae)

May 2015 - Phaeocystis (nuisance algae)

Summer 2014 - Sediment biodiversity

June 2014 - Phaeocystis (nuisance algae)

Summer 2013 - Sediment biodiversity

Summer 2012 - Sediment biodiversity

Summer 2012 - Phaeocystis (nuisance algae)

May 2012 - Alexandrium (Red Tide)

See older exceedances

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 617-788-4941, or e-mail us at