Keys Prepares For Rising Tides, More Frequent Floods

WLRN 91.3 FM | By Nancy Klingener

Published October 7, 2015 at 4:15 PM EDT

Even parts of Old Town Key West, like the intersection of Greene and Elizabeth streets, flooded during recent full moon high tides.

Recent full moon high tides combined with weather systems off the Atlantic coast to bring more than a week of "nuisance flooding" to streets along the Florida Keys.

And with sea level projected to rise between 3 and 7 inches by 2030, we can expect such events to become more frequent, according to Monroe County planners and consultants.

Nuisance flooding, like this at Key West's Bayview Park, was widespread throughout the Keys during recent full moon high tides. County planners and consultants warn it could become more frequent in the near future.

More than 25 people attended a sea level rise workshop this week in Key West, part of a series of events the county is holding to introduce its GreenKeys initiative. That involves both planning for how the county can cope with higher water and encouraging sustainable plans for reducing carbon emissions and green living.

A tide gauge at Key West Harbor has been measuring sea level for more than a century.

"In the last 100 years, right here in the Keys we've seen 9 inches of sea level rise documented," said Rhonda Haag, the county's sustainability program director.

A survey of 300 coastal counties ranked Monroe County third in the country in its vulnerability to sea level rise. That's led the county to look at its public infrastructure — from roads and parks to sewage treatment plants — to see how it would be affected when tides are higher.

Even U.S. 1 — the only route in or out of the Keys — has a worrisome low spot near Sea Oats Beach in Islamorada.

"That's not a nuisance," said Jason Evans, an assistant professor of environmental science at Stetson University, who is working with the county on sea-level-rise preparations. "That's really intolerable when you're talking about your main evacuation" route.

The county, in partnership with The Nature Conservancy, is also evaluating how sea level rise would affect natural habitats that the state, county and federal governments have spent millions to protect.

Pinerocklands are the rarest natural habitats left in the Keys — they're found only in the Lower Keys, Everglades National Park and a few patches in Miami-Dade County. And they rely on a lens of freshwater that is threatened by rising seas, said ChrisBergh,TNC's Keys program director.

Pine rocklands "are full of rare endemic species, things that are found nowhere else," Bergh said.

One piece of potentially good news: A preliminary run of the Coastal Adaptation of Sea Level Rise Tool — which measures the costs and the benefits of adaptation strategies — found that the benefits were high for elevating and floodproofing homes, compared to other areas of the country.

"It's very, very valuable real estate," Evans said. "Getting that out of harm's way ends up being very cost-effective because we have very, very high value houses here."