Oyster Roast (copy) (copy)

A sewer spill has closed oyster and other shellfish harvesting in the Charleston Harbor area. File/Grace Beahm/Staff

Less than a year after a massive sewer spill closed shellfish harvesting from Charleston Harbor south to the North Edisto River, another massive spill river has closed the harbor and most of the feeding rivers and creeks nearby.

The North Charleston Sewer District spill is conservatively estimated to be spilling 200,000 gallons per day since Nov. 1, said district spokesman Jarred Jones. A 40-year-old sewer line breached in the marshland at the end of Apple Street in the Wando Woods subdivision. A contractor has been working on the breach since Nov. 2.

"Access to the site is difficult and work can only be performed during low tide," Jones said. "Based on visual evidence, we believe the leak was caused by a manufacturing or installation defect at this point during original construction in the 1970s."

The S.C. Department of Health and Environmental Control closed the beds as required by law based on the volume spilled, Jones said.

"This closure affects all shellfish harvesting from Folly Road north to the Charleston Harbor," said Mike Pearson, manager of the DHEC shellfish sanitation section.

The map provided of the closure included surrounding waters such as the Cooper and Wando rivers, Wappoo and Shem creeks, as well as a portion of the Intracoastal Waterway behind Sullivan's Island.

"The affected area will reopen once water quality data indicates that bacteria levels are once again suitable for shellfish harvesting," Pearson said.

Fecal bacteria from sewage can be trapped in shellfish meat and cause health problems if the meat is eaten raw, which many consider a delicacy. The bacteria can be destroyed by cooking, but the more it's infested, the longer it has to cook. There's just no way to tell for sure without testing.

Sewer system discharge, rain runoff and litter are causing more pollution problems as population growth urbanizes the Charleston area. Shellfish bed harvest closures have become routine, at a rate beginning to threaten the local supplies of oysters and clams sought after as a succulent delicacy. Buffering and other pollution control methods haven't kept pace with waterfront development.

In February a breach in a sewer line serving the town of Hollywood spilled 3 million gallons of sewage, according to DHEC estimates.

The Stono and the rivers behind Folly Beach are the dominant oystering waterways in the area. The waters affected by the recent spill are not so heavily oystered.

The Stono closure disrupted at least two harvesting businesses and a number of wild harvesters. It also put more harvesting pressure on beds in others areas such as Bulls Bay, where professional oysterman Mike Anderson said earlier that people were stripping so many oysters from some beds, the oysters couldn't replenish.

Reach Bo Petersen Reporter at Facebook, @bopete on Twitter or 1-843-937-5744.

Science and environment reporter. Author of Washing Our Hands in the Clouds.