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1. What are flood insurance rate maps?

Flood Insurance Rate Maps (FIRMs) are the official maps on which Federal Emergency Management Agency (FEMA) has delineated Special Flood Hazard Areas (SFHAs) and flood risk zones. Data in the FIRMs can be used to determine the location of a property relative to special flood hazard areas, which is one of the factors determining flood insurance rates.

FIRMs are used by property owners, lenders, realtors and insurers. They are also used by local governments as tools for administering and enforcing local floodplain management regulations under the National Flood Insurance Program (NFIP) within SFHAs.

2. How can I find out if my property is in a special flood hazard area (SFHA)?

Snohomish County has FIRMs on file in the Planning and Development Services (PDS) Department for properties within the unincorporated county area.

You may view the maps at any time during business hours. PDS also offers a Flood Hazard Determination service for a $206 fee. This services includes the following information:

• Information about whether a property is located within a SFHA in Snohomish County.
• Information about the mandatory flood insurance purchase requirement.
• Flood insurance rating information such as FIRM zone, panel number, suffix, panel date, index date, and regulatory base flood elevation.

The Flood Hazard Determination is provided for the current flood maps, the FIRMs, as well as for a new set of flood maps, the Preliminary DFIRMs. The Preliminary DFIRMs are updated, digital versions of the FIRM. The Preliminary DFIRMs have not been released by FEMA for adoption. The County is using the Preliminary DFIRMs as best available data for regulatory purposes. Release of the Preliminary DFIRMs is on hold pending FEMA’s resolution of the levee analysis and mapping approach. More information on the DFIRMs is available on the DFIRM project webpage. The county distributes an annual notice to the most common users of this service, lenders, realtors, and insurers in the spring.

For more information on the Flood Hazard Determination, please call PDS at 425-388-3311, ext. 2731.

3. Are flood maps available online?

Yes. The effective Flood Insurance Rate Maps (FIRMs) are available through Federal Emergency Management Agency (FEMA) Map Service Center, or Snohomish County.

As a convenience to users of this site, we’ve provided links to FEMA websites that will help you find a quick, unofficial and reasonably accurate determination of your property’s flood risk.

• A good resource for assessing your risk of flooding and need for flood insurance is available through the National Flood Insurance Program FloodSmart website. Complete the "One Step Flood Risk Profile" for information on the flood risk of your property.
• FEMA flood zone designations and historic maps are available online through the FEMA Map Service Center.
• FIRMs identify the flood zone designations for a broad area. “FIRMettes” are maps for individual properties, which will identify the flood zone designation(s) for your property. Follow these steps to make a FIRMette for your property.

4. What other information might be available on the flood hazard for my property?

Elevation Certificates
Elevation certificates are important administrative tools of the National Flood Insurance Program that provide property information, Flood Insurance Rate Map (FIRM) information, and information about the physical attributes and elevations of subject buildings. Snohomish County has elevation certificates on file for structures on some properties within the Special Flood Hazard Area (SFHA), and will provide copies upon request. For more information, please contact Planning and Development Services at 425-388-3311, ext. 2731.

Flood studies and Flood Insurance Studies
Flood maps are based on studies of flooding in specific areas. Detailed flood studies incorporate a minimum of ten years of data on the frequency, size, and location of past floods to determine the probability that a flood of any size will be equaled or exceeded in a year. Approximate flood studies estimate flood hazard areas using available data. Information from individual studies are compiled in a comprehensive document known as the Flood Insurance Study (FIS). The FIRMs and DFIRMs depict the extents of the areas subject to flooding for rivers and streams in the FIS. The FIS for Snohomish County is available from the Surface Water Management Web site. (link) For more information, please contact Public Works Surface Water Management at 425-388-3464.

5. How are flood zone designations assigned?

Flood designations are based on statistical averages, not on the number of years between big floods. View more information on Flood Insurance Studies, including how to read a Flood Insurance Study.

6. Do flood designations change?

Flood risks can change over time, altering floodplain boundaries and flood zone designations. Changes in land use and development, dams and levees, and river processes and conditions can all affect the assessment of flood risk.

7. What other information is important to understand my property's flood risk?

The delineation of certain areas on Snohomish County’s adopted Flood Insurance Rate Maps (FIRMs) is based on studies that have been completed as many as 20-30 years ago. The Preliminary Digital Flood Insurance Rate Maps (DFIRMS), awaiting adoption, will have more data and better accuracy than the hard copy FIRMs for areas studied using detailed methods. Other areas, primarily the areas studied by approximate methods, will remain unchanged. The DFIRMs are digitized and use ortho photos (aerial photographs with the accuracy characteristics of a map) as the base map, and are based on more current studies in some areas. Please contact Surface Water Management at 425-388-3464 regarding the most up-to-date information on the flood history of your neighborhood.