About 7,200 acres of waters in Brookhaven, Southampton and East Hampton were reopened to shellfish harvesting at sunrise Thursday, the state Department of Environmental Conservation said.

The reopened waters include portions of Moriches Bay, Acabonac Harbor, Napeague Harbor and Montauk Harbor.

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More than 19,000 acres were closed to harvesting last Wednesday after heavy rainfall the previous day caused an extraordinary runoff into the waters, the agency said in a news release.

Large amounts of runoff "adversely affects water quality in shellfish harvesting areas and increases the potential for shellfish to be hazardous for human consumption," the agency said in explaining the temporary closure of the shellfish waters.

Between 7,400 and 7,500 acres were reopened Saturday, the agency said.

About 4,400 acres in the three towns remain closed to harvesting. Those waters "will be reopened as soon as water quality testing determines that conditions no longer exist that would make shellfish hazardous for use as food," the release said.

A recorded message advising harvesters of the status of affected shellfish areas may be heard at 631-444-0480, the release said.