CEDAR ISLAND -- Waterman Tommy Graham calls it "jetty swirl," a man-made smack that might just be the kiss of death for Cape Romain.

The cape is 100 square miles of waters and misted islands north of Charleston, a national wildlife refuge that might be the most valuable nursery of coastal creatures in the region. Everything from oysters to the rarely seen long-billed curlew call it home. If you live in the Lowcountry, you owe no small part of what you enjoy to Cape Romain, whether it's a plate of shrimp in a restaurant or a loggerhead turtle clambering up a beach.

The vast expanse is vanishing, barrier island after island eroding away. A century ago, Cedar Island was a beach town, a hamlet of cottages in the high dunes. Now it's an empty, nearly flat spit.

A generation ago, Sandy Point was one of the best oceanfront beaches for miles. That sand is now spread along the seafloor.

The culprits are the usual erosive suspects -- nor'easter winter storms, tropical cyclones, sea rise, even the damming of the Santee River to the cape's north.

But there's one large culprit that might not even occur to most people: the Georgetown jetties.

Some 10 miles to the cape's northeast, the jetties evidently exacerbate the erosion of nearly every island for more than 30 miles south, including all the critical barrier islands as far as Dewees.

But the effect has been largely overlooked, partly because the area is sparsely populated.

The erosive effect of the Charleston jetties on Morris Island and Folly Beach has been so thoroughly documented that Folly qualifies for federal beach renourishment money because of the studies. In contrast, when the U.S. Army Corps of Engineers is asked what studies have been done on the impact of the century-old Georgetown jetties, the answer is none.

A handful of Cape Romain watermen like Graham, some of whose families go back generations on the coast, have taken it on themselves to document the impact. Working from family lore about how islands have changed, they have assembled more than a century's worth of nautical charts, aerial photos and the like.

Their conclusion is stark.

"I'm afraid the human effect on the beach is the most profound and dynamic thing there is," Graham said.

'Starvation'

Change is a constant for barrier islands. The sands form and reform, migrating to the southwest, pushed by winds and currents that push in more sand. But what's happening now in Cape Romain is scary.

"The sand is moving. But there's nothing coming in to help restore the beach," said John Cox of Mount Pleasant, a fishing guide and coastal geologist who is working with Graham and others.

That's largely because of jetty swirl. The Georgetown jetties form a sea wall that extends 10 miles farther out to sea than most of the Cape Romain islands to the southwest. The southbound-shore currents swirl at that wall, and the sand they carry gets pushed back on beaches to the north.

And, when the Santee was dammed in the 1930s to create the Marion-Moultrie lakes, the downstream drift of the river's silt for the coastal marshes and sand for the cape beaches stopped.

"It's sediment starvation," Cox said.

Cedar Island is the barrier island where the Santee sweeps into the Atlantic Ocean. In the 19th century, the island was a prized beach and hunting cottage community combed with deer. As early as 1902, a Mr. Hamlin of the Santee Gun Club from nearly Murphy Island recounted a trip there.

"Mr. Dupree came aboard early with his hounds and we roamed over Cedar Island -- saw some deer tracks. Enjoyed a most delightful walk through the live oak road by the old summer houses, now in decay, to the sand dunes against which dashed the ever restless waves of the broad Atlantic," he wrote in the Early History of the Santee Gun Club.

On a Friday morning, Richard Wyndham of McClellanville walked the narrow strip of what's left of that dune beach, the place where he hunted with his grandfather, also a gun club member, the place where his great-grandfather wrecked a schooner.

He pointed out to Cox how much sand has been lost in just two years on the inlet beach where they land the boat.

"The cape has always been volatile, like any barrier island system. You can look offshore and you can find the relic of (an older) Cape Romain," Wyndham says. "Now we have this huge man-made contribution that the islands can't handle. They can't keep up. The way we are going, it's just going to be a giant mud flat out there."

'It's gone'

From Cedar Island, the Cape Romain lighthouse and Cape Island are tiny and far off; they look like a ghost ship lost at sea. The Cape Island beach, annually the nesting ground for one-third of the sea turtles that nest from Georgia to North Carolina, was washed over and sliced into inlets by Hurricane Irene in August.

Graham is 67 years old, a lifelong Cape Romain resident and one of the leaders in the effort to restore the century-old lighthouse. In his lifetime, the nearby beachfront Raccoon Key has been washed over and Sandy Point lost.

It used to be a huge pelican rookery with 6-foot-high dunes, he says. "It's gone. It's totally disappeared."

Cape Island used to be called "Cow Pens" by owners who would settle cattle out there to graze. Now it's little more than a strip. Ironically, Lighthouse Island behind it has steadily grown since the structure was built. "While one part is in crisis, the next part grows," he says.

But from what Graham has seen, from the old stories and the research, Graham concludes that the cape is losing islands more rapidly than it once did.

And there's one big difference today -- people. Places like Cape Romain have become critical habitat.

It used to be that when nesting turtles lost a beach, they could move to another, right along with the migrating sands. Now there's fewer uninhabited beaches, fewer nurseries for turtles and other wildlife.

"The cape is full of movement," he says. "If it's denied sediment, it can't change. And you starve it."