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Boston Harbor and Massachusetts Bay
MWRA Environmental Quality Department

Boston Harbor


Boston Harbor encompasses nearly 50 square miles and is an estuary, where fresh water from tributary rivers mix with the salt water of Massachusetts Bay. Long-term Harbor monitoring helps in identifying changes in water quality over time. Eight watersheds drain into the harbor; conditions in the wetlands, rivers, streams, groundwaters, and estuaries of Boston Harbor's watersheds are linked to the health of the harbor.

The Massachusetts Water Resources Authority monitors water quality at more than 50 locations in Boston Harbor.

Download Boston Harbor data below:

Click on this Boston Harbor sampling map for additional stations and station numbers
See larger map with sampling locations

Recent Harbor Temperatures (NOAA)


Download Water Quality Data


*For samples collected between June and October of each of the last five full calendar years.


See also: Boston Harbor's tributary rivers