ABOUT THE MYSTIC RIVER WATERSHED
A watershed is a land area draining to a river or other body of water, in this case, the Mystic River. Ridges on the horizon often define the boundaries of a watershed.
The Mystic River Watershed covers 76 square miles or roughly 1% of the land area of Massachusetts. Its headwaters begin in Reading, MA and form the Aberjona River, then flow into the Upper Mystic Lake in Winchester. From the Lower Mystic Lake, the Mystic River flows through Arlington, Somerville, Medford, Everett, Chelsea, Charlestown, and East Boston before emptying into Boston Harbor. Explore the Mystic River Watershed using our interactive Environmental Atlas!
The "Lower Mystic River Watershed" refers to the area below the Amelia Earhart Dam in Somerville, which is salt water. Whereas the "Upper Mystic River Watershed" refers to the freshwater area above the Amelia Earhart Dam.
There are 44 lakes and ponds within the Watershed, with Spot Pond being the largest standing body of water at 307 acres in size. The 22 communities within the Mystic River Watershed include:
- Arlington
- Belmont
- Boston (Charlestown & East Boston)
- Burlington
- Cambridge
- Chelsea
- Everett
- Lexington
- Malden
- Medford
- Melrose
- Reading
- Revere
- Somerville
- Stoneham
- Wakefield
- Watertown
- Wilmington
- Winchester
- Winthrop
- Woburn
Belle Isle Marsh
SUBWATERSHEDS
The Mystic River Watershed includes nine subwatersheds, listed below. Specific information related to these subbasins is available in the Mystic Action Plan, Chapter 2. (See a map of the subwatersheds here.)
- Aberjona Subbasin (~25% of the total watershed area)
- Horn Pond Subbasin
- Mystic Lakes Subbasin
- Mill Brook Subbasin
- Mystic River 1 Subbasin
- Alewife Brook Subbasin
- Malden River Subbasin
- Mystic River2 Subbasin
- Chelsea Creek Subbasin
ENVIRONMENTAL CONCERNS
The Mystic River Watershed is one of the most urban and densely populated watersheds in the Commonwealth. It has three Superfund sites within its borders, and is home to various Environmental Justice communities. The Mystic has a history of industry along it's banks - evidence of which continue to linger. Find out what environmental issues are present and current water quality information by following the links.
Since 1972, the Mystic River Watershed Association has been the one consistent voice speaking up for the Mystic River, it's tributaries and surrounding lands - read more about our work here.
TRIBUTARIES
Major tributaries of the Mystic River include Chelsea Creek, the Malden River, Alewife Brook, and the Aberjona River.
GET INVOLVED
Youth take water quality samples in Mill Creek
- Explore hiking, biking, boating and birding opportunities here.
- Become a volunteer!
- Find out what other groups are involved with the Mystic River Watershed on Our Partners list.
- Now, take ACTION to help protect and restore the Mystic River!
- Stay informed about watershed news by subscribing to our monthly E-Newsletter.
- Share the Mystic with your friends! Download a brochure about the Mystic River Watershed here.
- Donate or Join to support a healthy watershed!
- Learn what native plants call the Mystic home.
- Educational resources are available here.
RESEARCH
View a list of research and publications concerning the Mystic River Watershed here.



