Flood protection in Fort Lauderdale

Fort Lauderdale's flood insurance class

Fort Lauderdale is a Class 7 community in FEMA's Community Rating System: a 15% flood premium reduction in Special Flood Hazard Areas (zones AE, AO, AH and VE) and 10% in Zone X. The City's list includes coastal VE zones, where FEMA does not allow floodproofing below the base flood elevation at all.

Flood protection is designed around that flood zone and insurance picture.[1][2]

King tides and street flooding

The City tells owners to inspect and maintain their seawalls, says walls overtopped by king tides should be raised to the 5 ft standard, and can cite owners whose walls let tidal water reach the street. A low spot or a leaking joint is a code issue here, not only a maintenance one.

If the city is citing overtopping walls, flood protection and a wall raise are usually planned together.[3][4]

River tide and inlet tide

NOAA's South Port Everglades gauge shows a 2.79 ft great diurnal range, while the Andrews Avenue bridge gauge up the New River shows 2.28 ft, with mean higher high water about 0.45 to 0.57 ft above NAVD 88 (1983 to 2001 epoch). Lifts and floating docks near the inlet need more travel than those up the river.

Tide and king tide levels show how often water reaches the property today.[5][6]

5 ft NAVD88, with a path to 2050

New and substantially repaired tidal barriers in Fort Lauderdale must reach 5 ft NAVD88. A wall permitted before 1 January 2035 may be built at 4 ft NAVD88 if it is designed to be raised to 5 ft by 1 January 2050, which is how many owners spread the cost.

The seawall stops tidal overtopping; barriers and vents protect the building behind it.[4]

What makes Fort Lauderdale different

The City treats seawalls as tidal barriers. It presumes a wall is in disrepair if it lets upland soil erode, lets material pass through it, or lets tidal water flow unimpeded onto neighbours or the street, and gives owners 60 days to show progress and 365 days to finish. The City also spends $1.5 million a year on its own seawalls.[4][3]

The county layer

Broward County requires a license before any work in, on, over or under its waters, including repairing or replacing a dock or seawall. Broward's regional policy is a consistent top elevation of 5 ft NAVD for seawalls, banks and berms.[7][4]

Permits for flood protection in Fort Lauderdale

• Broward County environmental licensing: A county license before any work in, on, over or under Broward County waters, including dock and seawall repair.
• City of Fort Lauderdale: Building permits; waivers of the dock and lift projection limit go to the City Commission with a Marine Advisory Board recommendation.
• Florida DEP or South Florida Water Management District: State permit or exemption for docks and walls on the New River and the Intracoastal, on top of the Broward County license.
• US Army Corps of Engineers, Jacksonville District: Federal authorisation for work in the Intracoastal Waterway and other navigable waters.

Why a seawall alone does not stop flooding

Miami Beach notes that groundwater rises through the porous limestone under the city, so seawalls by themselves cannot stop flooding. Barriers, vents and drainage each handle a different path the water takes.[9]

Frequently asked questions