MIAMI -- A bird's eye look at the Florida Keys is all it takes to understand that little stands between the chain of islands and the sea.
A new federal study all but confirms that there are few big, structural options to keep the Keys safe from the stronger hurricanes and rising seas that climate change is expected to bring. The answer, it suggests, is a combination of elevation and retreat.
In a presentation shown to Monroe County Commissioners last week, the Army Corps of Engineers outlined a $3 billion strategy to protect the Keys. The only new construction measure considered is adding additional rocks on either side of U.S. 1 in six key spots. The rest of the plan is a combination of elevating homes, businesses and essential buildings and "retreat" in the form of government-funded buyouts.
"It is less traditional that our usual coastal studies," said Susan Layton, the Corps chief of planning and policy for the Norfolk District and lead for the Monroe County project. "You really cannot keep the water back, so really a lot more of this project is how do we react to the water and live with the water to make the Keys a viable place to live and make that lifestyle available for as many years as possible."
In Miami-Dade, the federal engineering team is proposing dramatic construction fixes, including 10 to 13-foot walls along the coast, surge barriers at the mouths of rivers and thousands of home elevations and buyouts.
The Keys plan would skip the massive walls and instead pay to floodproof or even elevate all the "critical infrastructure" in the Keys, which includes hospitals, fire and police stations and water treatment facilities.
It's unclear precisely how many private homes and businesses could face the prospect of elevation or buyouts. Army Corps officials offered estimates during an unrecorded webinar with Monroe County officials in January, but they were not included in last week's presentation and Corps and county officials declined to disclose them.
"We don't have numbers that we have enough confidence in to release," said Layton.
Those numbers will include the 62 Keys properties already in line to sell their homes to the state after damage from 2017's Hurricane Irma. The state has considered re-opening the pot of money after considerable interest in the Keys. The homes are expected to be sold and demolished in about a year, although homeowners are allowed to back out of the process at any time.
But unlike the state buyout program, which will purchase homes sporadically around the Keys, the Corps plans to buy out a concentrated area to avoid "checkerboarding" of city services and flood protection.