Some Keys roads will flood by 2025 due to sea rise. Fixing them could cost $750 million

·4 min read

As the staggering price tag of elevating roads in the Florida Keys comes into focus, where exactly all that cash will come from remains unclear.

Consultants tasked with figuring out which roads should be elevated above rising seas first (and how much that might cost) have estimated that raising 155 miles of Monroe County roads could cost $1.8 billion. And those are just the roads at risk by 2045. The county maintains 311 miles of road — not including U.S. 1, the main road that is also known as the Overseas Highway, or city roads in places like Key West and Marathon.

At a presentation to the county commission on Wednesday, consultants said about $750 million of those projects may be needed in just the next four years.

Emilio Corrales, a project manager at consulting firm HDR, said his team identified 28 project areas, including one on Big Coppitt Key, where roads could be flooded with more than 6 inches of water during king tides by 2025. King tides are the highest tides of the year, and sea level rise is pushing them even higher.

The list of projects isn’t public, but about 55% of them are in the lower keys and 40% are in the upper keys.

Sections marked red on this map of Big Coppitt Key indicate roads that could see more than 6 inches of flooding during King Tides as soon as 2025. Other roads won’t see flooding like that for several more years.
Sections marked red on this map of Big Coppitt Key indicate roads that could see more than 6 inches of flooding during King Tides as soon as 2025. Other roads won’t see flooding like that for several more years.

Monroe County Chief Resilience Officer Rhonda Haag called it a preliminary list based purely on the depth of flooding and how many residents live on each road. Questions about how each project could affect residents or empty lots could convince commissioners to change the way they rank each project.

“It could entirely change by the time we get through the policy decisions,” she said.

The costs depend on the length of the road, but they’re high. The shortest project would raise just .034 miles of road in Key Largo’s Tavernier Cove — for $65,000. The longest project, 8.6 miles of road in Stock Island, is also the most expensive at nearly $100 million.

Miles of Florida roads face ‘major problem’ from sea rise. Is state moving fast enough?

These costs are several times higher than simple road projects in less flood-prone counties. That’s because engineers can’t just slap an extra foot of asphalt on the road and call it a day. They need to build pipes and pumps to carry the water off roads when sea rise gets so high that gravity is no longer on their side. They also need to clean the water before releasing it back into the ocean.

In some cases, the roads would only be raised a few feet, despite the fact that projections are around 6 feet of sea rise by 2100.

“What happens after 2045? Well, if you have a good foundation there’s a chance you can build on top of that,” Corrales said.

During the presentation, he also noted that the cost of maintaining all 60 projects once they’re completed could cost roughly $2 million a year.

Raising Keys roads for sea rise could cost $1.8 billion. Residents may pay much of that bill

Raising taxes vs. rising seas

Monroe hasn’t figured out how it’s going to come up with the billions it needs to keep its roads (mostly) dry.

Hiking the island county’s sales tax another percent — to 8.5% — could raise $300 million, but it requires permission from state leadership.

“We are not bringing it up this session due to the current leadership in Tallahassee. We have not abandoned the idea and plan to bring it forward again during the 2023 session,” said Roman Gastesi, Monroe County’s administrator.

The other big idea is assessments on the communities benefiting from the raised roads. One estimate last year suggested that residents of Twin Lakes in Key Largo could be charged $5,000 each for the $7.3 million project if there are no grants to offset the price. So far, Monroe hasn’t done anything besides talk about the potential assessments.

“We haven’t moved forward because we’re trying to get the demo projects off the ground,” Haag said. “There’s a lot of moving parts to determine in an assessment.”

This map shows the proposed elevation needed to keep swatch on this road in Conch Key dry by 2045. Some areas could be raised as high as 2.25 feet, while others would see less than a foot of extra elevation.
This map shows the proposed elevation needed to keep swatch on this road in Conch Key dry by 2045. Some areas could be raised as high as 2.25 feet, while others would see less than a foot of extra elevation.

The Twin Lakes project is one of two demonstration projects Haag hopes will make the case that road raising is doable and helpful. The other project, in the Sand neighborhood of Big Pine Key, recently won a federal CDBG grant to cover 75% of construction costs. Design for the project was also grant-funded.

Haag said the county has put in for several grants, including with the new billion-dollar Resilience Florida state fund, to fund construction in the Twin Lakes neighborhood and design for the Stillwright Point neighborhood in Key Largo.

Stillwright Point made headlines a few years back when the streets stayed flooded for 90 days, which led residents to push for their neighborhood to be included as one of the first road-raising projects. During the Wednesday presentation, Corrales said the Stillwright Point roads would see the most dramatic elevation change in the county.