FOLLY BEACH — Cristen Hampton used to have a fire pit in her backyard. Now she has a wall. 

Hampton was sick of the island's back marsh, just about 15 feet from her home here, backing up into her property during high tides and serious storms. During a few events, she had a foot and a half of water in her basement. 

"I had a black snake swim in from the marsh" during Irma last year, Hampton said. 

Now, when the marsh floods, the house is protected by a wall on the small back porch, erected from the cinderblocks that once made up the Hamptons' fire pit. 

Hampton is one of many islanders who has lived firsthand a circumstance that might surprise inland residents. While beachfront homes are vulnerable, marshfront land often floods first. 

Folly Beach is currently considering a plan to keep construction and development away from the marshes on its back side, a relatively new approach to protecting an important coastal resource.

The city is considering a proposal to add extra restrictions to building on marsh islands between Folly and James islands. It's also weighing a 15-foot setback for new construction on the back of Folly Island, with a 10-foot setback for existing structures. 

The Folly package of regulations would be some of the strictest marshland protections in the state. The S.C. Department of Health and Environmental Control does have specific rules about what can be built in coastal marshes, which are protected similarly to other wetland areas. But the areas are not as protected as the beachfront, which in most areas is subject to a setback line that gives the beach a buffer. 

And while that beachfront line was erased in a revision this year signed by Gov. Henry McMaster, the state's Beachfront Management Act originally included a policy that assumed homes would have to retreat from the beach over time. That policy did not extend to the coastal marshes typically found on the back sides of barrier islands. 

Like beaches, marshes can move as the sea level changes, migrating upward as water rises. But also like beaches, hard structures get in the way, potentially choking off important habitat. 

"Whether we can really appreciate it or not, we are the caretaker of one of the most critical biomes in the world," said Albert George, conservation director for the South Carolina Aquarium. 

'Nursery of the oceans'

South Carolina's coastal marshes are crucial, George said, because they provide habitat in estuaries where freshwater rivers meet the ocean. In addition to supporting species such as the crabs commonly found scuttling around the pluff mud, marshes are the "nursery of the oceans," serving both freshwater and saltwater fish species.

"It creates the haven for freshwater and pelagic (open-ocean) species during their initial phases of development to get strong," George said.  

While these marshlands serve several species with ideal nesting grounds, they're relatively concentrated in the Southeast. About two-thirds of the coastal salt marshes on the Atlantic Seaboard are found between Georgetown and Jacksonville, Fla., George said. 

They're also important ecosystems for other reasons, serving as carbon "sinks" that are able to efficiently suck up the carbon-based greenhouse gasses that contribute to global warming and its byproduct, sea level rise. 

Studies in South Carolina have shown, however, that marshes in many places are steadily eroding already.

The situation in many areas around Charleston is likely to get worse, as the region's marshes are pinched on both sides by huge pressures — rising water levels and coastal development.  

"Not to be fatalistic and not to be romantic, but it’s almost like we're loving it too much," George said, "because we want to be so close to it, (but) we’re almost imprisoning that marsh."

Development pressures

As South Carolina's beachfront land has been largely developed, a continuing crush of new coastal arrivals still look for homes in natural settings, and the Lowcountry's quintessential landscape — twisting creeks and spartina grass fields — have become the next best option.

For some, it's even preferable to the beach itself.  

"I love the marsh. Front beach is nice, but there's solitude on the back side (of the island)," said Isle of Palms Mayor Jimmy Carroll, who is also a real estate agent. "I love watching the turning of the marshes from vivid greens in August to golden in the fall." 

While beachfront properties are sometimes thought of as the most vulnerable, marshfront homes don't have the benefit of a sloping beach or dune system that might fend off the water.

Folly Beach and Kiawah Island have conducted sea level rise studies, and both found that as the ocean inches upward, the backside of their respective islands are most vulnerable to flooding, along the marsh. 

Marshes are particularly susceptible to flooding during abnormally high tides, creating the kind of situation that prompted Hampton to build a wall in her backyard on Folly. During an intense rain, water might also back up because many islands drain runoff to their marsh sides, providing an avenue for water to back up the pipes if they don't drain fast enough.

While many houses along the marsh are raised to avoid flooding damage, inundations still cause mayhem, covering roads with water and forcing residents to scramble to protect their cars and other property. 

On Folly, the safest place for a car in the flood is the BP gas station. When the water's rising, Hampton said everyone tries to park their vehicle there. 

"It's just worse and worse," Hampton said of the flooding. 

Reach Chloe Johnson at 843-735-9985. Follow her on Twitter @_ChloeAJ.