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Flooding is the temporary overflow of water onto land that is normally dry.  Severe flooding typically occurs when intense rain falls over a short period of time, prolonged rain falls over several days, or debris causes a river to overflow into the surrounding area - in each case, water accumulates faster than soils can absorb it or rivers can carry it away.  Flooding can also result from the failure of a water control structure, such as a levee or dam.  Being flood-ready can protect property and save lives.  

Know the flood risks for your neighborhood!  The Federal Emergency Management Agency (FEMA) manages the National Flood Insurance Program (NFIP) and maintains large Flood Insurance Rate Maps (FIRMs) for the entire country.  FIRMs assign each mapped area a Flood Zone Letter based on the likelihood and type of flooding, including potential depth and velocity.  To get a FEMA FIRMette (a smaller version FIRM) of your neighborhood, Click HERE and enter your address. 

  • Zones with a letter grade of A or V are considered high-risk Special Flood Hazard Areas (SFHA) with a 1% chance of severe flood in any given year (a "100-year flood") - that means a 26% chance of damaging flood waters during a 30-year mortgage period. 

  • Zones with letter grades of B, C, or X are considered to have a moderate or low risk for damaging floods (0.2% chance each year, a "500-year flood") but still account for 20 to 25 percent of NFIP claims each year. 

Residents in unincorporated Nassau County and in the City of Fernandina Beach benefit from discounts on flood insurance rates garnered through floodplain management and the jurisdiction's participation in the NFIP Community Rating System.  

Floods kill more people in the US each year than tornadoes, hurricanes, or lightning.  Take steps now to mitigate flood damage by flood-proofing your home.  Flood waters can carry dangerous debris, sewage, and chemicals; destroy buildings, roads, vehicles, and crops; kill wildlife, livestock, and pets; and spread infectious diseases.   Click HERE for FEMA's Ready Business Flood Planning Toolkit.

Click HERE for more Flood Safety tips.   

Failing to evacuate flooded areas, entering flood waters, or remaining after a flood has passed can result in injury or death
Graphic of storm cloud, hour glass and power lines flash with text saying floods come from rain storms, surge, and other water systems, can develop with with no warning, and cause power outages, disrupt transportation, damage buildings, and create landslides overflow dams

Types of Flooding

  • Flash floods are exactly what the name suggests:  floods that happen in a flash!  Intense rain can bring more water than the soil can absorb.  Excess water quickly overwhelms storm drains and ditches, rising significantly in a short amount of time. 

  • River flooding occurs when river levels rise and overflow their banks and inundate areas that are normally dry.  It can be caused by heavy rainfall, dam failures, blocked waterways, or the natural watershed system.  The National Weather Service issues Flood Warnings for designated River Forecast Points where depths considered "flood stage" have been established.  River flooding is classified as  Minor, Moderate, or Major based on water height and impacts.  

  • Coastal flooding generally occurs with a land-falling or near-land storm system but can occur with seasonal above-average high tides.  The excess rain and seawater inundates low-lying wetlands and dry land, erodes shorelines, increases the flow of salt water into estuaries and nearby groundwater aquifers, and makes coastal infrastructure more vulnerable to damage from subsequent storms.

  • Storm Surge is the rise in seawater level caused solely by an approaching off-shore storm or Tropical Cyclone.  It is measured as the height of the water above the normal astronomical tide.  The surge is caused primarily by a storm’s winds pushing water onshore, but surge height at any given location depends on the shape of the coastline; the storm track or angle of approach; the intensity, size, and forward speed of the system; and the depth and topography of the ocean floor offshore.  Storm tide is the total height that seawater reaches during a storm, the combination of storm surge waves and the normal tide.  The destructive power of storm surge and its large battering waves can result in loss of life, destruction of buildings, erosion of beaches and dunes, and damage to roads and bridges along the coast.  Storm surges undermine building foundations by constant agitation of the water piled high by the tropical cyclone.  Storm surge can also travel several miles inland, resulting in the complete demolition of homes and businesses.  

Graphic heading says Prepare Now surrounded by a Blue Circle


Graphic heading says Survive During the Hazard surrounded by Orange Circle


Graphic heading says Be Safe After the Hazard surrounded by Green Circle


  • Sign up for Flood Watches and Warnings through the AlertNassau notification system.  

  • Keep your home flood-ready.  Declutter drains and gutters.  Install plumbing check valves.  Consider installing a sump pump with a backup battery.  Move valued items to higher levels in the house. 

  • Homeowner’s insurance policies do not cover flooding.  Obtain coverage for potential flood losses through the NFIP.    

  • Make a Plan.  Identify and practice evacuation routes, shelter plans, and flash flood response.

  • Build a Kit.  Gather supplies in case you have to leave immediately or if services are cut off.  Obtain extra batteries and charging devices for phones and other critical equipment.  Keep in mind each person’s specific needs, including medication.  Don’t forget the needs of pets.  

  • Keep important documents like insurance and vaccination records in a waterproof container.  Photograph documents and property to create password-protected digital copies. 

  • Learn when and how to use sandbags properly.  

  • Listen to local news and public safety officials for current emergency information and instructions.

  • Bring in outdoor items (lawn furniture, grills, trash cans) or tie them down securely.

  • If told to evacuate, do so immediately.  turn off all utilities at the main power switch, close the main gas valve, and go to the safe location that you have identified. 

  • Never drive around barricades.  Local responders use them to safely direct traffic out of flooded areas.  

  • Do not walk, swim, or drive through flood waters.  Turn Around - Don’t Drown.  Just six inches of fast-moving water can knock you down, and one foot of moving water can sweep your vehicle away. 

  • Stay off of bridges over fast-moving water.  Fast-moving water can wash bridges away without warning. 

  • If your vehicle is trapped in rapidly moving water, stay inside.  If water is rising inside the vehicle, seek refuge on its roof.

  • If trapped in a building, go to its highest level.  Do not climb into a closed attic.  You may become trapped by rising floodwater.  Go on the roof only if necessary to signal for help.

Graphic illustrates filling sandbags one-half to two-thirds full and tied near the top, and proper stacking of sandbags in an effective berm with a layer of plastic sheeting and a width three times its height
small decorative image of Gumby
  • Listen to authorities for information and instructions.  Avoid driving, except in emergencies.  Do not visit disaster areas. Your presence may hamper rescue and other emergency operations.

  • Avoid wading through floodwater, it is likely contaminated and can contain dangerous debris.  Underground or downed power lines can also electrically charge the water. 

  • Do not enter a flood-damaged home or building until it has been cleared by authorities.  If you enter a flood-damaged building, be extremely careful.  Water can cause walls to collapse, ceilings to fall, etc.  

  • If the house has been flooded be aware that snakes and other animals may be in your house; it might also be contaminated with sewage or chemicals.

  • Be aware of the risk of electrocution.  Do not touch electrical equipment if it is wet or if you are standing in water.  

  • If the house has been closed up for a few days, assume it has mold; enter briefly to open doors and windows to let the house air out at least 30 minutes before you stay for any length of time.

  • Document damage and contact your insurance agent.

  • Conduct clean-up safely.

  • Wear heavy gloves and boots during clean-up.  Get rid of any standing water indoors to reduce the likelihood of mold and additional damage.  

  • Follow food safety guidelines; clean and sanitize surfaces that have been flooded; make sure food is not contaminated or spoiled.

  • Ensure tap water is safe for drinking, cooking, and cleaning.  Authorities may issue a "boil water notice" after a flood.  If you have a well, make sure it is disinfected and tested before using the water.  

  • Use a generator or other gasoline-powered machinery ONLY outdoors and away from windows.  

  • Follow debris removal guidelines for the separation of post-storm and flood debris.  Do not put used sandbags in the trash for pick-up.  

NWS graphic describing the differences between a Stream Advisory, Flood Watch, Flash Flood Watch, Flood Warning, Flash Flood Warning, and Flash Flood Emergency.
Flood Advisory, Watch, and Warning
Floodproof Home
Graphic illustrating how storm surge builds as it approaches shore
Storm Surge Vide
turn around flood graphic.jpg
CDC graphic of food items to discard after a flood to prevent infectious disease from contamination, and how to sanitize surfaces with a solution of 1 tablespoon of bleach in 1 gallon of water
After a Flood
Debris Removal Guidelines
Debris Removal Guidelines.png
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