City of Key Colony Beach Official City Website

Flood Hazard Mapping

Preliminary Coastal Maps

In December 2019, the Federal Emergency Management Agency (FEMA) released new PRELIMINARY coastal flood maps after a multi-year study of Monroe County’s coastal flood risks. After an extensive vetting process, these maps will replace the current flood maps. The current maps are based on 30-plus-year-old studies.

Monroe County wants to ensure all residents and business owners are aware of the potential for a change in flood risk for their property so that they can be more proactive in reducing their flood risk.

View Preliminary Coastal Maps

Monroe County GIS Mapping tool

Coastal Flood Maps, otherwise known as Flood Insurance Rate Maps (FIRMs) are used to determine the minimum elevation needed for construction to reduce the chances of flooding, as well as construction methods required in certain zones.


Select State (FL), County (Monroe County) to get to the webpage listing various area maps. Warning maps on the site are very large and may take several minutes to open/download.

IMPORTANT: These maps don’t show an additional difference in elevation due to a change in mapping standards between the old and new proposed flood maps (datum NGVD29-> NAVD88). This means that all NGVD29 elevations (e.g., BFE, Lowest Floor Elevation) need to be converted to NAVD88. While there is no set conversion factor, as it varies throughout Monroe County, on average there is -1.5 foot conversion. To account for this change, ON AVERAGE you should add +1.5 foot to any apparent increase. For example, if your building was in an AE-8 flood zone and is still shown in an AE-8 zone, then it actually experienced an increase of 1.5 feet. Another example, if your building was in an AE-6 flood zone and is proposed to be in an AE-9 zone, the increase appears to be three-feet.  However, the actual increase would be 4.5 feet.

To convert one vertical datum to another, visit the ArcGIS SFWMD Elevation Conversion: NGVD29 to NAVD88 mapping tool

View Current Flood Maps

Visit the FEMA Flood Map Service Center and search by property address.

Flood Risk and New Building

To emphasize that flood risks are changing and to make sure property owners understand this is coming, Monroe County Building Department will be requiring owner’s to sign a form with permits that acknowledge the issuance of these new PRELIMINARY coastal flood maps and the fact that these maps may indicate a future change to the required elevation of a building currently being permitted.

Building Department Permit Application with new signature page 

This is intended to help homeowners understand that what they might be proposing to build today, under the existing flood maps, could become non-conforming after the maps are changed, thereby making their flood risk and insurance costs greater. Owners should think about designing their improvements to meet the proposed PRELIMINARY maps to assure they are addressing potential future risks.