Discover The Pond

Edgartown Great Pond and the south shore barrier beach.

Edgartown Great Pond and the south shore barrier beach, courtesy of David Foster.

Edgartown Great Pond is an 890 acre (at high water) brackish coastal pond located on the South Shore of Martha’s Vineyard.  A thin strip of beach called a “barrier beach” separates the shoreline of the Pond from the Atlantic Ocean.  Four times a year the narrowest portion of the barrier beach is cut open to the Atlantic Ocean.  The influx of salty water from this cut to the ocean increases the salinity, reduces the temperature, and refreshes the Pond with tidal flushes throughout the duration of the opening.  Over the course of time the tides begin to fill in the cut and the barrier beach heals itself.  The tradition of cutting the Pond comes from the Wampanoag Tribe who historically dug the opening in the barrier beach to maintain the water quality for their fishery.

Frequently Asked Questions

What is a great pond?

There are 16 great ponds on Martha’s Vineyard.  Per the Massachusetts DEP:

A great pond is defined as any pond or lake that contained more than 10 acres in its natural state. Ponds that once measured 10 or more acres in their natural state, but which are now smaller, are still considered great ponds.

What is brackish water?

Brackish water is a mixture of saline water from the ocean and fresh water inputs from the estuary.  Ocean water has a salinity of approximately 33 ppt.  Edgartown Great Pond is quite salty with salinity ranging from 20-25 ppt for most of the year.  The more recent the Pond opening, the higher the salinity of the Pond.

What lives in and around the Pond?

Edgartown Great Pond is home to more than just people. Every summer, beach-nesting shorebirds like Piping Plovers, Least Terns and American Oystercatchers reside on the barrier beach. These birds tend to feed on the marine worms, clams, oysters, and other invertebrates found in and around the pond shore. Otters have been spotted swimming around the many coves and upper basin of the Great Pond where they will find eels and other fish on which to snack. Herons, Belted Kingfishers and Osprey can also be seen fishing around the coves on a quiet afternoon. These are just a few of the many species that can be seen in and around Edgartown Great Pond. Click for #animalsofedgartowngreatpond  and #animalsofmv.

Who helps to protect the Pond?

We have many conservation partners that work to protect and preserve Edgartown Great Pond and its surrounding habitat.  BiodiversityWorks is a wildlife monitoring organization that spearheads the study and protection of beach nesting shorebirds and other wildlife on the Pond.  The Martha’s Vineyard Shellfish Group has been successfully restoring the oyster population to the Pond for over a decade.  Polly Hill Arboretum is in the process of completing its Flora of the Island and including a survey of the plants of Edgartown Great Pond.  The Martha’s Vineyard Commission monitors the health of Edgartown Great Pond in addition to the other 27 brackish and saltwater Island ponds.  Sheriff’s Meadow Foundation, Mass Audubon, and MV Land Bank all conserve portions of land around the Pond. To learn more about the Great Pond Foundation and our partners in conservation please Explore Our Work.