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Flood Map Updates

Flood risk changes over time due to natural and man-made changes. The corresponding flood maps are revised periodically to reflect these changes and to improve map accuracy using better data and technology. The City and County of Denver works with MHFD and FEMA to study flood risk and update flood maps.

Major Flood Map Revisions ("Physical Map Revision" or PMR)

A PMR is a FEMA process that is used for large changes to the Flood Insurance Rate Map (FIRM) and are commonly used to incorporate MHFD Flood Hazard Area Delineation (FHAD) studies into the FEMA FIRMs.

Minor Flood Map Revisions (called "Letter of Map Change" or LOMC)

  • A FEMA Letter of Map Revision (LOMR) is used to update flood maps to reflect changes as a result of a construction project.
  • A FEMA Letter of Map Amendment (LOMA) can be used to remove a building or property from the SFHA when inadvertently mapped in the SFHA. A successful LOMA can help reduce or eliminate flood insurance premiums. This typically requires the services of a Professional Land Surveyor and may require an elevation certificate. If you think you may be inadvertently mapped in the SFHA, please contact the City & County of Denver's Floodplain Management Group at or 720-865-3215 for guidance.

If you live in an area that is under revision

  • Property owners will be notified by MHFD of any FIRM revisions — whether you are at increased risk or have been added to the SFHA, or if you are at reduced risk or removed from the SFHA
  • You are not required to do anything until you are officially notified of a change in the FIRM. However, it is recommended that all flood risk information be considered for emergency planning, mitigation, flood insurance, and development/redevelopment purposes. Carefully consider the impacts of a future FIRM change, especially when developing or redeveloping a property. It is not advised to develop/redevelop in a manner that increases flood risk and thus may impact future flood insurance rates.
  • Consider purchasing flood insurance, even if it is not currently required; there may be benefits for current policyholders if your property's flood risk changes. 
  • If you have questions about buying or selling your property during the study period, please consult with your real estate agent.