The Massachusetts Water Resources Authority (MWRA) officially opened the Massachusetts Bay effluent outfall in September 2000, and stopped discharging treated wastewater (effluent) to Boston Harbor. The results shown by years of monitoring are a cleaner Harbor and a healthy Bay.
Printable pamphlet on MWRA monitoring
Monitoring Bacteria in the Bay
MWRA monitors bacteria around the MWRA outfall and elsewhere in Massachusetts Bay (see station map below).The U.S. Environmental Protection Agency uses enterococcus as an indicator of public health risk to saltwater swimmers. Enterococcus has a 35 organisms/100 ml limit for recreational use waters. The Mass. Division of Marine Fisheries monitors water quality in shellfish areas by measuring fecal coliform, which has a 14 organisms/100 ml limit.
Download MWRA Mass. Bay bacteria data
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MWRA has monitored the bay's water quality since 1992, as part of a carefully designed Ambient Monitoring Program. We have found that while effluent quality has improved, animal communities in the bay continue to thrive. Images from the outfall reflect a healthy, vibrant ecosystem.
Also receiving a clean bill of health are Cape Cod Bay and Stellwagen Bank National Marine Sanctuary, a feeding ground for the right whale. Detailed results are available in the annual Outfall Monitoring Overview.