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• 178 to 241 acres, depending on water level
• 3,500-acre watershed

One of several Great Ponds that are a unique feature on the Island’s south shore, Chilmark Pond is a small cousin to the Tisbury Great Pond, surrounded by marshland that rises steeply to grassy, high moors. Regular, manmade breaching of the barrier beach opens the pond to the Atlantic Ocean, increasing salinity and flushing nitrogen.

The pond is closed to shellfishing and in fact supports little shellfish. Nitrogen levels are high at times and there has been a historic loss of eelgrass over the past 50 years. The town of Chilmark and Martha’s Vineyard Shellfish Group are pursuing a plan to create oyster reefs and ribbed mussel beds to filter the water and remove nitrogen and bacteria.