BALTIMORE (WJZ) — The Maryland Department of the Environment issued an emergency closure to shellfish harvesting Monday in a portion of the Potomac River off St. Mary’s County.

The order applies to around 180 acres of the river offshore from the St. George Island area. The closure was prompted by a sewage spill inspectors believe entered the river.

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The department believes about 2,500 gallons of sewage went into the river after an overflow on Piney Point Road that started last Wednesday and ended Sunday. An estimated 11,000 gallons were vacuumed from ditches that lead to the river, officials said.

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Shellfish feed using a filtering process that can concentrate disease-causing organisms, the department explained. Oysters and clams, which are often eaten raw, need to come from unpolluted waters.

The department said it will sample water in the affected area to determine when it is safe to harvest again. The earliest the closure will be lifted is Dec. 20.

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Areas of the Potomac River off St. Mary’s County have been closed to harvesting twice already this year for sewage spills. The MDE said it will request a meeting with the County Commission “on the repeated system failures and plans to address the sewage spills.”

CBS Baltimore Staff