MWRA State of Boston Harbor

Boston Harbor and Massachusetts Bay
MWRA Environmental Quality Department

Bacteria at Boston Harbor Beaches

Beach water quality is generally good, but there is no clear trend, with year-to-year variations at each beach.









These graphs show the percent of water samples that failed standards for bacteria (Enterococcus), with a count above the limit of 104 colonies per 100 mililiters.

HARBOR BEACHES ARE SWIMMABLE MOST OF THE TIME

The water quality variations of Boston Harbor's beaches reflect a complex urban coastline. For example, Tenean Beach shows an increased frequency of high counts during rainy summers, but Wollaston does not. Efforts by MWRA and communities, including MWRA’s CSO Control Plan, have significantly reduced the volume of untreated CSO discharges to the harbor since the late 1980s. Treatment plant discharges and much of the combined sewage in the harbor have been eliminated.