Know Your Flood Risk

Find Out if Your Property is in a Flood Zone

The Federal Emergency Management Agency (FEMA) has a number of online resources that can help you estimate your property’s flood risk:

  • The National Flood Insurance Program's FloodSmart website is a good place to start. Click on "Flood Zones and Maps” to learn how to find and read flood maps for your area.
  • The official flood maps issued by FEMA are called Flood Insurance Rate Maps (FIRMs). These maps, which are used to set flood insurance requirements and costs, show flood zones within a community. Each flood zone describes the flood risk for a specific area. To view the FIRM that covers your neighborhood, please visit the FEMA Flood Map Service Center and enter your address. 
  • The FEMA Flood Map Service Center has a feature that allows you to create and print a small flood map, or “FIRMette,” for your property. Click here for instructions.
  • Call the Snohomish County Department of Planning and Development Services (PDS) at 425-388-3311 for more information on the flood risk for your neighborhood.

How FEMA Designates Flood Risk

The flood zones shown on FIRMs are based on flood insurance studies of specific areas. To produce these studies, FEMA compiles at least 10 years of data on the frequency, sizes and locations of past floods, and then determines the probability that a flood of any size will be equaled or exceeded in a year. Please note that flood zone designations are based on statistical averages, not on the number of years between big floods. Visit the FEMA website to learn more about flood insurance studies, including how to read the studies. 


Flood zones shown on Snohomish County’s adopted FIRMs are based on local studies that were completed as many as 20 to 30 years ago. New Digital Flood Insurance Rate Maps (DFIRMs), which incorporate more recent studies, will be adopted by the county on or before June 19, 2020. You can learn more about DFIRMs here, and by contacting PDS at 425-388-3311. 


Changing Your Flood Zone Designation

One of the flood zones shown on a FIRM is the Special Flood Hazard Area (SFHA). The SFHA, sometimes called the 100-year floodplain, is the area that has a one percent or greater chance of flooding in any given year. Sometimes, FEMA may inadvertently include parcels within an SFHA even though the properties are on natural ground and are at or above the elevation of the 100-year flood, commonly called the Base Flood Elevation (BFE). FEMA may also inadvertently map some properties into an SFHA even though they were elevated to or above the BFE with earthen fill.  


If you believe that your home and/or land is not within the SFHA on your community’s FIRM, you may ask FEMA to amend the FIRM to remove the property from the SFHA. You can submit your request through one of two processes: the Letter of Map Amendment (LOMA) process or the Letter of Map Revision–Based on Fill (LOMR-F) process. You will need to submit mapping and survey information to FEMA as part of these processes. For more information, please see the following links: