What Happens When FEMA Updates Your Flood Map?

Flood risk is not static. The landscape changes due to development, erosion, infrastructure projects, and natural events. FEMA revises Flood Insurance Rate Maps (FIRMs) to reflect these changes and ensure the maps remain as accurate as possible. Common triggers for a map update include:

• New or updated Flood Insurance Studies: FEMA commissions engineering studies that use updated topographic data, improved hydraulic models, and more recent rainfall and stream flow statistics.
• Development and land use changes: New construction, paving, grading, and other development can alter drainage patterns and increase runoff, changing the extent of flood hazard areas.
• Levee and dam changes: If a levee is decertified, repaired, or a new flood control structure is built, the areas protected (or no longer protected) by these systems may change zones.
• Improved mapping technology: LiDAR elevation data and more precise surveying methods can reveal that existing maps over- or under-estimated flood boundaries in certain areas.
• Community requests: Local governments can request map revisions when they have data showing the current maps are inaccurate for their jurisdiction.

A FEMA flood map revision follows a structured process that typically takes several years from start to finish. Understanding this timeline helps you anticipate changes and respond appropriately.

• Check for preliminary maps: Visit the FEMA Map Service Center to see if a preliminary FIRM has been issued for your community. This gives you advance notice of potential changes before they become effective.
• Submit an appeal during the review period: If you believe the preliminary map is inaccurate for your property, you can submit scientific or technical data during the appeal period. An Elevation Certificate from a licensed surveyor is often the strongest evidence.
• Apply for a LOMA after the map becomes effective: If you missed the appeal period or acquired new data, you can apply for a Letter of Map Amendment (LOMA) to have your property individually reclassified if your natural ground elevation is above the BFE.
• Maintain continuous coverage: If you currently have flood insurance, maintaining continuous coverage protects your eligibility for certain grandfathering provisions and prevents gaps that could be costly if your zone changes.

Under the traditional NFIP rating system, properties that were built in compliance with the flood map in effect at the time of construction could be "grandfathered" and rated using the original zone and BFE even after a map revision. This often resulted in lower premiums than the new map would otherwise produce.