Floodplain and Flooding Information

FAQs - How to Prevent or Minimize Flood Damage

(Thanks to the City of Myrtle Beach, SC for permission to use its online “Flood Protection Tips” brochure as a model for this article)

What is a floodplain?


Floodplains serve many useful purposes, and the undisturbed areas on Key Biscayne that exist in a natural state perform a number of beneficial functions with respect to the hazards of flooding. They moderate the amount of flooding, they retain floodwaters, they reduce erosion and sedimentation damages, and they mitigate the effects of waves and storm surges produced during storms and tropical cyclones. In addition they provide habitat for fish and wildlife.

For these reasons, the Village of Key Biscayne, located in the center 1.25 square miles of a four-mile-long, two-mile-wide barrier island between the Atlantic Ocean and Biscayne Bay, is involved in many efforts to preserve and protect public spaces. Short- and long-term programs include beach health, maintenance, and improvement programs as well as maintenance programs for bayfront mangrove preserves.

The Village is bordered by nearly 30 acres of pristine Atlantic beach to the east, by Miami-Dade County's Crandon Park to the north, and to the south by Bill Baggs Cape Florida State Park. Efforts are ongoing within the Village to increase parklands through the conversion of unused paved areas to their natural state.

Properties in the Village are in a Federal Emergency Management Agency (FEMA)-designated flood hazard area. In order to obtain flood insurance, the Village participates in floodplain management practices as part of the National Flood Insurance Program (NFIP). The 9.5-acre Village Green in the center of the Village of Key Biscayne is a park with passive areas, open fields used for recreational sports, a mulch-surfaced playground, shelters, and restrooms. The park is bordered by swales that drain the playing fields as well as sidewalks that abut streets to the east, west and south. Lake Park and the oceanfront Beach Park, totaling almost 2 acres in size, contribute to flood management as passive parks.

What causes flooding in Key Biscayne?

Much flooding on the island of Key Biscayne is caused by surges of Atlantic Ocean water and rain driven landward by tropical storms and hurricanes. Atlantic storms usually approach from the east, south, southeast or northeast and cause flooding along and from the beachfront. Storms approaching from the Gulf of Mexico and Caribbean Basin (west to southwest) have caused storm surges along the island’s Biscayne Bay frontage. Occasionally, heavy non-tropical rains will cause localized freshwater flooding. A Village-wide stormwater drainage project completed in 1996 alleviated chronic flooding problems after even short-intensity rainstorms.

Flood waters associated with major tropical cyclones along the beachfront can rise to heights of 15 to 20 feet above mean sea level, with destructive waves reaching even higher. Most of the land within the Village is in the floodplain. Low-lying older structures are more prone to flooding than newer elevated structures built to base flood elevation (BFE).

Major recent storms affecting the Key Biscayne area include Hurricane Andrew (1992), Hurricane Katrina (2005) and Hurricane Wilma (2005). The last major storm prior to Andrew was Hurricane Betsy (1965). Hurricanes not only create floods, but may cause erosion of the shoreline which increases the likelihood and severity of oceanfront flooding during subsequent storms.

What can I expect if a storm approaches?

The Village of Key Biscayne coordinates with the Miami-Dade County Office of Emergency Management, the National Weather Service, and the National Hurricane Center in issuing public warnings concerning expected floods, storms and hurricanes. Local television and radio stations provide local weather information and advisories, such as warnings for heavy rain, flash floods, coastal flooding, tropical storms and hurricanes. A hurricane watch indicates that a hurricane poses a possible threat within 24 to 36 hours. A hurricane warning means that hurricane conditions are expected within 24 hours. You should prepare to take action, up to and including evacuation.

The Village of Key Biscayne urges all residents and property owners to evacuate the island to the mainland via the Rickenbacker Causeway. Once an evacuation is ordered by government officials, leave Key Biscayne as quickly as possible and evacuate to a pre-arranged location safe from wind and water or a County shelter. If you are disabled, under a doctor’s care or require special help, you can register with the Metro-Dade County Office of Emergency Management by calling 305-273-6700.

Before you evacuate, follow these flood safety precautions:

  • Know appropriate escape routes
  • Remember to turn off your electricity, house power
  • Close all your windows, doors and shutters
  • Prepare emergency supplies of food, water, medicine and other essentials such as batteries, portable radio, flashlights, important documents, etc. so they will be readily available upon evacuation
  • If you have time, move your valuables and furniture to elevated areas that are less prone to water damage

What can I do to decrease my risk of injury during a flood?

Residents of flood hazard areas can take the following actions to decrease the risk of injury due to flooding.

  • Do not walk through flowing water. Currents can be deceptive; six inches of moving water can knock you off your feet. In standing water, use a pole or stick to determine depth.
  • Do not drive through flooded areas and do not drive around road barriers. Roads or bridges may be washed out.∑ Keep children away from flood waters, ditches, culverts and drains.
  • Stay away from power lines and electrical wires. Electrical current will travel through water. Report downed power lines to Florida Power & Light at 1-800-4OUTAGE (1-800-468-8243).
  • Turn off all electrical circuits at the panel or disconnect all electrical appliances.
  • Watch for animals, including snakes. Small animals that have been flooded out of their homes may seek shelter in yours. Use a pole or stick to prod and turn over and scare away small animals.
  • Look before you step. After a flood, the ground and floors may be covered with debris, including glass and nails. Floors and stairs covered with mud can be very slippery.
  • Be alert for gas/propane leaks. Use a flashlight to inspect for damage. Do not smoke or use candles, lanterns, or open flames unless you know that the gas has been turned off and the area has been ventilated.

Is my home in a floodplain?

If you live in the Village of Key Biscayne, your property is in a flood hazard area as mapped by FEMA. The Village’s Chief Building Official, Eugenio M. Santiago, P.E., a Certified Floodplain Manager, can assist you with maps and flood protection information and provide advice on retrofitting techniques for structures in the floodplain. The Department of Building, Planning, Zoning and Public Works (BZPPW; 305-365-5501) is located in Suite 250 of Village Hall at 88 West McIntyre Street. Also available for review are past and current FEMA Flood Insurance Rate Maps (FIRM), and topographical maps that show elevations of property within the city. FEMA FIRM maps, reference materials, pamphlets and videos also are available at the Key Biscayne Library.

What is required to apply for a building permit in a flood plain?

The Village’s zoning ordinance identifies portions of the community within the 100-year floodplain, an area with a one percent chance of flooding in any given year. The zoning ordinance and building codes have special provisions regulating construction and other development within those floodplains. Without those provisions, flood insurance through the National Flood Insurance Program (NFIP) would not be available to property owners and renters in the Village of Key Biscayne.

Before you build, fill or otherwise develop in a floodplain, contact BZPPW to discuss regulations.  All development in the regulatory floodplain requires an Elevation Certificate before, during, and after construction.  An Elevation Certificate form is available online from FEMA (PDF) or from BZPPWCopies of previously submitted Elevation Certificates are available online or in Suite 250 for review during regular business hours.

Any development in the floodplain without a permit is illegal; such activity should be reported to the Director of BZPPW (305-365-8908) or the Chief Building Official (305-365-8902).

What can I do to avoid flooding in my home?

The Village of Key Biscayne requires that all new residential structures in the regulatory floodplain be elevated no less than the base flood elevation. It may be possible to retrofit existing structures by various floodproofing techniques. If you are unable to retrofit your structure, the next most effective means is to elevate your structure above the base flood elevation. The Village’s Department of Building, Zoning, Planning and Public Works (BZPPW) can discuss emergency, temporary and permanent alternatives with you and help you obtain the necessary permits. The Key Biscayne Library has reference information available for review regarding temporary and permanent property protection, retrofitting and flood proofing structures.

You can take protection measures as follows:

  • Re-grading your lot or construction of a small floodwall or earthen berm my help protect a larger property from non-major flooding.
  • Another approach is to make your walls waterproof and place watertight closures over doorways.  This method is not recommended if you have a basement or if water depth will exceed 2 feet.
  • Check with a plumber about a plug or standpipe that can stop sanitary sewer backups if the water does not get more than 1-2 feet deep. A backup valve may be required to prevent sewer backups during heavier flooding.
  • Make sure that storm sewer inlets and drainage swales near your property are clear of debris and functioning properly.
  • If you know a flood is coming, move valuable contents upstairs or to an elevated location or take them with you.
  • Keep plywood, plastic sheeting, lumber, sandbags and a basic tool kit handy for emergencies.

Keep in mind that any alteration to your building or land, including regarding or filling, requires a permit from BZPPW. A permit also may be needed to ensure that projects on your property do not cause problems on adjacent properties.

What is the “50% Rule” and why must new homes be elevated?

The so-called “50%” rule or “substantial improvement” rule applies to all work done to an existing structure, including additions during the preceding year. If the total dollar value of this work equals to or exceeds 50% of the market value of your structure (not including the value of the land), your entire structure will need to be raised to base flood elevation or otherwise floodproofed to withstand floods reaching base flood elevation.

The federal government requires the Village of Key Biscayne to have an ordinance enforcing this rule. A copy of this Ordinance may be obtained through the Department of Building, Zoning, Planning and Public Works. Failure of the Village to effectively enforce the Substantial Improvement Rule may result in the virtual unavailability of federal flood insurance in Key Biscayne.

In order to prevent localized flooding outside of special flood hazard areas, the Village Building Code requires the minimum finished floor elevation for new construction to be at least 18 inches above the highest crown of any abutting street or 24 inches above the average grade of the lot.  The lowest floor and all mechanical or electrical equipment must meet these elevation requirements.  Further, final site grading shall insure that ponding of stormwater will not occur beneath the building nor nearer than three feet from the building perimeter or any mechanical or electrical equipment.

Who is responsible for storm drain maintenance?

The Village of Key Biscayne minimizes flood damage by improving and maintaining a storm drainage system completed in 1996. This system consists of catch basins connected to state-of-the-art deep injection wells. The Public Works Division of the Department of Building, Zoning, Planning and Public Works cleans all catch basins at least twice a year to insure efficient operation.

These Village efforts require your cooperation and assistance. Here’s how you can help:

  • Debris in drainage ditches, storm sewer inlet basins and pipes can cause localized flooding during rainfall events. Even grass clippings and branches can accumulate and plug channels. A plugged channel cannot carry water and, when it rains, the water has to go somewhere.
  • Dumping or throwing anything into ditches, water channels, inlets and catch basins is a Village Ordinance violation.
  • If your property is next to a ditch or a channel, please do your part and keep the banks clear of brush and debris. Village code requires all owners or occupants of property to remove obstructions from the drainage system on their property. The Village can help remove major blockages such as downed trees.

For questions, to report obstructions or violations, or to request assistance, call the Public Works Division at (305) 365-8945.

I've had flood damage to my home or business.  Who do I call?

A permit issued by the Department of Building, Zoning, Planning and Public Works is required to make any repairs to flood-damaged buildings. Buildings with damage amounting to 50 percent or more of the building’s value must be removed or brought into full compliance with the floodplain regulations. Buildings existing in a flood plain that do not meet the current regulations may only be improved to less than 50 percent of the building’s value. Additions or alterations that are not a result of storm damage also are limited to less than 50 percent of the building’s value.

The requirements of the zoning ordinance and building codes are minimum standards that all development must meet. To increase the safety of your property and reduce insurance premiums, you should consider building to higher standards. Of course, the safest way to develop your property is to locate improvements outside of the flood plain.



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