DFIRM Floodplain Maps

Definition & Purpose

Flood Insurance Rate Maps (FIRMs) are official maps on which the Federal Emergency Management Agency (FEMA) has delineated flood hazard areas and risk zones. They show the location of a property relative to flood hazard areas, which is one of the factors used to calculate flood insurance rates. More information on FIRMs is available at the FloodSmart.gov website.


FIRMs are used by:

  • Homeowners, insurance agents, and real estate brokers to determine if a specific property or building is in a flood hazard area;
  • Planning staff and building officials to administer floodplain management regulations and to mitigate flood damage; and
  • Lending institutions and federal agencies to locate properties and buildings in relation to mapped flood hazards, and to determine if flood insurance is required when making loans for the purchase or construction of a building or for providing grants after a disaster.

Updated Maps

The county partnered with FEMA to produce updated Preliminary Digital Flood Insurance Rate Maps (DFIRMs) for Snohomish County. FEMA issued a Final Letter of Determination regarding the DFIRMs on December 19, 2019. The DFIRMs were adopted by the county in June 2020.


To access the current DFIRMS online, visit the FEMA Map Service Center