Is Johns Island built-out? At 84 square miles, it’s the fourth-biggest island on the East Coast, about a third of it in the city of Charleston and within a self-imposed Urban Growth Boundary (UGB). About a dozen housing developments are underway at any given time, and the community has nearly doubled in population since 2000 to about 21,500 people. Right now, about 3,000 more housing starts are already permitted. And infrastructure — roads, water and sewer — is lagging far behind growth.

On Tuesday a developer will ask City Council to rezone 108 acres of light industrial property next to the executive airport to allow as many as 300 new homes.

Maybe it’s time to take a breather, as on James Island, where the clock is ticking on a six-month development moratorium. It’s been years since the city or county has updated community plans for Johns Island and nearly two decades since the UGB was put into place.

Phil Dustan, an islander campaigning against the airport-adjacent rezoning, sees Johns Island at a tipping point. Most of the land in question is just 6-8 feet above sea level, he says, and it will eventually flood. Developers, he explains, typically clear the trees, sell the lumber, scrape off the topsoil and sell it, then dig a retention pond and use its sandy clay to effectively seal unpaved surfaces before laying sod. To Mr. Dustan, that’s a recipe for disaster. He’s gathered 1,973 petition signatures aimed at sending the rezoning request back to the Planning Commission.

Given the threat of flooding, the 2007 Johns Island Community Plan recommends building at least 15 feet above sea level.

Brad DeVos of the Johns Island Community Association (JICA) takes a middle-ground approach. He wouldn’t call the island built-out, but “we’re starting to ask what that would look like.” He agrees with Mr. Dustan that the island needs a “watershed analysis” to better gauge flood hazards.

Mr. DeVos doesn’t necessarily see anything wrong with the planned development near the airport. It’s within the city limits and the UGB, and he’d prefer housing to “light industrial” development. Still, JICA has been asking the city for a two-year cap on residential housing, mainly to give infrastructure a chance to catch up to development. He’s been frustrated with the slow pace of road improvements.

“As long as we keep telling people this is just a rural community, the longer people out here will suffer,” he said.

Most of the Johns Island residents who showed up for a meet-and-greet with Congressman Mark Sanford last week expressed concern about overdevelopment. Kevin Hiott, a 30-year island resident, said it appeared the city was simply approving development to expand its tax base without coordinating infrastructure improvements.

Mr. Hiott said a four-hour traffic jam caused by a wreck on Maybank Highway Wednesday summed up the need for improved roadways: “It’s a safety hazard. God forbid if there were some other kind of emergency, with only one other way off the island. ”

Charleston City Planner Jacob Lindsay recognizes the need for intrastructure to catch up, and says the city is working toward a “permit allocation” system that ties new development to infrastructure improvements.

With thousands of housing units already in the pipeline, City Council should be reluctant to approve more housing on the outer edge of the UGB. It’s clearly time for a development pause and for the city to update its decade-old Johns Island Community Plan before the island is “built out.”