Facing regular floods, a Louisiana town builds higher

Hop on the narrow Lake Pontchartrain bridge in New Orleans, drive 35 miles north across the lake, and you'll get to the historic resort town of Mandeville, Louisiana. Right on the shore, just yards from the water, sits a stately white house with an American flag in the front yard. The style is typical Louisiana Creole, with a deep front porch and big black storm shutters. What used to be the ground floor, though, is now 15 steps up — nearly 9 feet above the ground.

Leonard and Becky Rohrbough own this house, which was built in 1843. It's been in Leonard's family since the early 1900s, and it's survived a lot of storms.

"Katrina was the worst," Leonard Rohrbough said.

In 2005, when the house was just 3 feet off the ground, Hurricane Katrina sent waves from the lake rushing under the house, inches from going inside.

"The streets just looked like pick-up sticks — telephone poles, trees, power wires, everywhere," Becky said. "It took us 45 minutes, climbing up and over and under trees to get to the house to discover that it was still here."

The house was intact, but the foundation was badly damaged. Then, 7 years later, Hurricane Isaac roared through, bringing the lake once again nearly into their house and eating away at the foundation.

"We said, 'OK, we've got to go up,'" Leonard recalled.

So up they went. In 2016, the Rohrboughs hired a contractor to dig tunnels under the house, lift it with hydraulic jacks and build a new, higher foundation underneath. Of course, lifting a 2,600-square-foot house is no easy feat.

"We used 27 jacks," Leonard said. "They had a gauge on each one, and after he lifted it up, he added up where the needle stopped on all of the gauges."

The total weight: 235,000 pounds.

"We'd go a few blocks away to the house where we were renting to stay while this was going on," Becky said, "and every night I would just pray that my house didn't topple over."

It didn't, but the whole process took about three months and costly roughly $250,000, which they covered with some grants and a low-interest disaster loan. Becky had just retired as a banker and said she was a little nervous taking on debt just as her paychecks stopped coming. But since they elevated, she said their house has about doubled in value. Their flood insurance premiums also went down.

"When I look at it now, it was probably one of the best financial decisions we ever made," she said.

They use the space underneath the house for storage. It's covered with a decorative lattice. When Ida hit last year and devastated the region, they fared OK.

"Lake Pontchartrain just flows under our house and out the backyard," Becky said. "Then, when this wind's done, it all goes back down into Lake Pontchartrain. Gravity takes over and that makes it a lot easier to clean up."

Mandeville is a charming town, full of historic buildings and the world's oldest continuously operating jazz hall. But in the past few decades, it's faced a growing threat of flooding from a combination of sea level rise, sinking ground and more intense storms. Hurricanes and tropical storms can push water from the Gulf of Mexico into Lake Pontchartrain and over the 5-foot seawall that lines the shore.

"We've had 17 floods in 17 years since Katrina," said Roderick Scott, a longtime Mandeville resident and board chairman of the Flood Mitigation Industry Association.

In the years since Katrina, Scott said more than 85% of buildings in Mandeville's lake surge zone have been elevated. He sees the city as a model for other coastal and river communities that will have to elevate as the climate crisis brings more flooding. The industry estimates 3 to 4 million older buildings, worth a collective $1.5 trillion, are at risk.

"Mandeville is the laboratory," he said. "We literally are lifting two or three right now. Every month, a couple of them go up."

At first, as with any lab, there were mistakes. On a walking tour, Scott showed us what must have been a cute wooden house now perched way up on these oversized brick columns, with cars parked underneath. It was kind of like seeing into someone's garage.

"We've got some ugly ones that came up first and we realized right away we didn't want to do that again," he said.

Since then, the city has adopted architectural guidelines. Mandeville is a pretty wealthy town, and a lot of homeowners have paid for their own elevations. Grants from the Federal Emergency Management Agency, and a new federal loan program starting in 2023, will help others.

But with at least 2 to 3 feet of sea level rise expected along the Louisiana coast by the end of the century, Scott said moving up only buys so much time.

"We feel the rate at which the sea level is rising, that we've got two more mortgage cycles at the shore before we have to move buildings back, before you cannot occupy them because the services don't work and you can't get to them," he said.

That's about 60 years. The good news, he said, is that once you've lifted a house off the ground, it's easier to move it to a new location in the future.

"We adapt or we lose," Scott said. "We become dinosaurs, and so we really have no choice."

For more on how people and communities are adapting to sea level rise, check out our podcast "How We Survive."