Pollution from stormwater threatens harbor

A generation after tougher industrial pollution laws cleaned up the nearly fetid water of Charleston Harbor, stormwater runoff has begun to threaten it.

Monitoring in the harbor has found spots where the water quality is considered "fair to poor" for supporting marine life, in contrast to the overall good shape of coastal water across the state, according to the 2006 state Department of Natural Resources coastal resources report. The trouble spots are feeder creeks in developed areas.

The state has taken regular samples from 60 sites along the length of the coast since 1999.

"I see some real problems," said Bob Van Doolah, director of the department's Marine Resources Research Institute. "The concern is that we get to a point where we really can't fix the problem."

Thirty years ago the culprits were wastewater discharge and industrial pollution. Today, the big problem appears to be impervious surfaces: roofs, streets, parking lots that drain instead of absorbing rain. That stormwater runoff carries everything from gasoline and oil to pet waste into the streams.

The pollution can't readily be captured and treated, and states are just beginning to recognize its impact. Wetlands absorb some of the pollution and have been a major reason Charleston-area estuaries have stayed relatively clean while development has boomed.

By contrast, in Myrtle Beach stormwater runs almost directly from pavement into the ocean. The state issued 684 no-swim advisories in 2006, according to the Natural Resources Defense Council, an environmental advocacy group that releases an annual report on the nation's beaches. Nearly all of them were for beaches along the Grand Strand.

"The thing about stormwater is that it doesn't go to a treatment plant. It just goes straight into the waterway," said Nancy Stoner, the council's water program director. "The solution is to try and capture that stormwater and have it soak through the ground. That's the best filter."

Stormwater pollution can overwhelm a waterway protected from other sewage discharge. In the metropolitan area around Charleston, 135,000 more homes are planned. The U.S. Census Bureau estimates that 10,000 people per year moving are in. Land is being developed five times faster than the population is growing.

The problem is new to regulators and complex: In some cases development retention ponds, a standard run-off pollution filter, appear to cause waste bacteria problems in nearby waters because so many wild animals frequent the buffer areas around them.

Water quality protection standards were designed for development 30 years ago, not the "lush lawn" development we have now, said Tom Siewicki, a National Oceanic and Atmospheric Administration environmental toxicologist at Fort Johnson. "We really don't know how to do it now."

Hard surfaces now cover 14 percent of Charleston County, up from 10 percent a decade ago. In some locations close to the water, the Charleston peninsula for example, the percentage is much higher.

A local study, one of the few that has been done, suggests that when 30 percent of the surrounding land is impervious, the runoff causes shellfish beds to be closed to harvest and the numbers of shrimp to decline; and the marine food web suffers. The study of a James Island creek was done by Fred Holland, federal Hollings Marine Laboratory director, and Denise Sanger, state marine scientist.

The study also indicated that damage begins at 10 percent. Once 10 percent of the land is covered over, nearby waters show changes in their levels of waste bacteria, chemical contaminants and sediments. At 20 percent, fish and shellfish nurseries start to suffer.

Analysis of 1995 satellite images done by biologist Phillip Dustan and an associate at the College of Charleston indicated the county had 10 percent impervious surface in 1995. David White, Hollings Marine Laboratory data manager, working from more current satellite images to chart impervious surface across the Charleston area, arrived at the 14 percent estimate

"I think we already ought to be in a (water quality) restoration mode," said Dustan, who worked on the state's 1998 Charleston Harbor Project study that showed the Cooper River had already reached the point at which it was taking as much pollution as it could handle.

Not everyone agrees tougher restrictions are needed. Charleston Harbor today is closed to oyster harvesting but open to fishing and shrimping.

"I was told when I started, 'Population and shellfish don't mix. It's all going to close.' That hasn't happened," said Toby Van Buren of Mount Pleasant, an oysterman who works beds behind Breach Inlet.

Meanwhile the marine resource managers watch and worry.

"I think we're doing a pretty good job. We're under an awful lot of pressure. Everybody wants to live next to the water," said Charles Newell, state Department of Health and Environmental Control shellfish program manager. "Every time someone puts up a house or a parking lot, that's just less permeable surface for drainage."

Reach Bo Petersen at 745-5852 or bpetersen@postandcourier.com.