Johns Island flooding (copy)

Contractors clear land and build roads for a new subdivision on Johns Island's River Road. File/Brad Nettles/Staff

For months, Johns Island residents have been in an uproar about new subdivision developments that seem to be causing flooding problems that they say weren't there before the onslaught of construction.

Up until the past few weeks, Mayor John Tecklenburg has assumed the more pressing problem was the island's lack of transportation infrastructure to handle the incoming traffic.

Tecklenburg said he's realized after a few rage-filled meetings with Johns Islanders that more focus needs to be on drainage, and City Council seemed to agree on Tuesday. They're considering halting new developments planned in flood-prone properties on the island for a short period to give city staff time to update the stormwater manual.

But the rules already on the books suggest that the city can do more than raise the bar for future developments. The rules give the city broad powers to demand better stormwater systems when developers are planning to build in areas with known flooding problems, even after the projects are initially approved. 

The city can also hold builders accountable when systems don't function they way they were designed to. 

Officials in the Public Service Department can point to instances where they have done those things, at least in other parts of town such as James Island and outer West Ashley. On Johns Island, it's proven to be more challenging. 

Murky situation

The once rural sea island is now Charleston's fastest-growing area, partly because it's one of the only places left in the city with vast sums of vacant land. 

The problem is, city leaders directed the growth there years ago without a full understanding of its unique dune-like topography. Maybank Highway is one of two large ridges of high ground, and the swails between them use a network of streams and wetlands to drain stormwater to the Stono River. 

While many of the new subdivisions are in the high areas, others are filling in those lower areas and causing flooding problems that have ripple effects for existing neighborhoods and possibly others that are on the way. 

A moratorium would affect projects that haven't been issued a building permit yet, and city attorneys will have to determine which developments it would apply to. It's unclear if developers that already have drainage plans would be sent back to the drawing board after the rules are updated.

If an area has proven flooding conditions, the city can require developers to go beyond the usual standards, according to city drainage laws. But Johns Island's flooding problems aren't as well-known as in other areas, such as downtown Charleston and the Church Creek drainage basin, said Public Service Director Laura Cabiness.

The only issues she's familiar with are in two Maybank Highway subdivisions, Barberry Woods and its next door neighbor, The Cottages. Both are off Maybank Highway and River Road.

The Barberry Woods developer built the community in the early 2000s with a drainage system that couldn't handle the total amount of runoff in the area. The city took the builders to municipal court and got them to improve the system, but it's still causing problems.

The city hired engineering firm Davis & Floyd for $77,500 last year to study the area to come up with a solution. Cabiness didn't know how much the developer will end up paying, or how much the improvement project could cost overall.

So, while the city has the authority to inspect drainage systems after they're built and require owners to remedy any problems, it's not always a clear-cut process. That's why it could be challenging to hold individual developers responsible for Johns Island's issues.

"It's not any one development, maybe, that's caused a problem. It's a combination of developments over a long period of time," Cabiness said.

Residents have also recently complained in community meetings about developers filling in land above the elevation of their older homes, which they say slopes stormwater into their yards. Cabiness said she hasn't received complaints about specific areas to look into, but she cited an old state rule that regards water as a common enemy. In theory, it allows property owners to drain water onto other properties. A city code specifies that a development shouldn't flood its neighbors.

"City laws can't necessarily trump state laws," Cabiness said.

However, the S.C. Municipal Association has concluded, based on case law, that the rule is outdated and that one property's drainage should not negatively impact surrounding property owners.

On the horizon

The stormwater manual is being updated for the whole city, not just Johns Island. But a moratorium there could be the best opportunity to get to the root of the problems and begin planning projects with an overall understanding of how the island's water naturally flows, officials said.

With 1.5 to 2 feet of sea level rise expected over the next 50 years, many emerging subdivisions on the edge of Johns Island will begin to see more water more often. And considering the effort by the federal government to make it easier for developers to fill in wetlands, environmental experts say the stakes are especially high for low-lying places like Johns Island.

At least six projects are planned in the special flood hazard area on Johns Island. Wetlands permeate many of those properties because they've naturally evolved to help the land absorb water, but if too many are filled in, more flood waters will likely wash over properties.

"The rollbacks they’re trying to do in Washington will leave people on the coast less protected, and they’re going to hurt our waterways," said Blan Holman, an attorney with the Southern Environmental Law Center. "That’s just another reason for local government to be vigilant."

Residents and even members of the Planning Commission have made it clear they expect major policy changes to set Johns Island on a new course. Whether that's a realistic goal for the moratorium remains to be seen.

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Reach Abigail Darlington at 843-937-5906 and follow her on Twitter @A_Big_Gail.