For the second time this month, Sengekontacket Pond has been closed to shellfishing because of rainfall.

The town of Oak Bluffs reported on their website that the pond was closed Wednesday and would reopen on Monday, July 20 at the earliest. If there is more rainfall, the closure could be extended.

Heavy rain and thunderstorms are expected on the Vineyard and other parts of southeastern Massachusetts Wednesday evening, and the National Weather Service has issued a flash flood watch for parts of the mainland, including Plymouth and Barnstable counties.

The pond was also closed to shellfishing because of rainfall over the Fourth of July holiday weekend.

The state mandates that saltwater ponds are closed to shellfishing as a precautionary measure after heavy rainfall, which could wash pollutants into the water from roads and other sources, like waterfowl.

Red flags fly at both of the bridges on Sengekontacket to indicate the pond is closures.

Oak Bluffs harbor is also closed to shellfishing. All of Lagoon Pond is open.