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
more than 50 locations in Boston Harbor.