As the Charleston peninsula grew over the centuries, developers filled in marshes and creek beds to build neighborhoods and roads. Not surprisingly, those places now flood after heavy rain and sometimes on sunny days as well.

The same thing happened much more recently as developers filled in and built on land around the Church Creek basin in West Ashley. Last year, FEMA helped buy out dozens of homes in that area that had flooded repeatedly.

It’s going to cost about $2 billion to fix identified flooding problems in the Charleston city limits alone, and city officials don’t have many realistic options for getting that much money in the short term. It’s a mess, and many residents are rightly upset that their investments and livelihoods are imperiled by the poor planning of previous generations and the indomitability of nature.

Lesson learned? Apparently not.

Development proceeds at a breathtaking pace on low-lying Johns Island. And aside from advances in dirt-moving technology since the 18th and 19th centuries, the strategy for building hasn’t changed much. Clear cut trees, fill in swampy land and cover it with homes and roads.

Obviously that’s going to cause problems. In fact it’s already too late according to some Johns Island residents whose relatively new neighborhoods suffer from regular flooding.

But despite the lessons of previous development failures and a sensible but largely ignored 2007 Johns Island Community Plan, there aren’t a lot of hard and fast guidelines developers have to follow regarding stormwater management. Many of them simply choose to build retention ponds, which collect water from the immediate surroundings but can exacerbate runoff in adjacent neighborhoods.

That kind of bare minimum approach to flood management allows developers to unload a tremendous future financial burden onto unsuspecting homebuyers — along with every taxpayer not just in Charleston but around the country.

Significantly downzoning large portions of Johns Island would be tricky. Any such effort would be subject to lawsuits, and would require detailed flood-risk studies. Nevertheless, at least one such study is thankfully already underway, according to a city spokesman.

But there’s no reason developers shouldn’t be required to provide for safety and livability by building homes higher off the ground, adding effective pump and drainage systems and utilizing porous paving techniques, for example. Development patterns that pose demonstrable risks to residents shouldn’t be allowed.

And not just on Johns Island.

Almost the entire Charleston region — part of the South Carolina Lowcountry — is at or near sea level. Much of it floods after rain. More of it floods during unusually high tides. Most of it floods during major storms like Tropical Storm Irma that hit last September.

And pretty much all of it will be susceptible to flooding as sea levels continue to rise, which all available data suggest will happen. Average water levels in Charleston Harbor are about a foot higher today than they were a century ago. Another foot would be disastrous.

We already know the cost of the build-now-adapt-later pattern — $2 billion in flood mitigation infrastructure and millions in home improvements and buyouts. It makes far more financial sense to build for the future.