Assessing Your Personal Risk

Find Out if Your Property is in a High Flood Risk Area
The following links to Federal Emergency Management Agency (FEMA) websites will help you find a quick, unofficial, and reasonably accurate determination of your property’s flood risk:
  • A good place to begin is the National Flood Insurance Program FloodSmart website. Complete the “One Step Flood Risk Profile” for information on the flood risk of your property.
  • Flood Insurance Rate Maps (FIRMs) identify the flood zone designations for a broad area. “FIRMettes” are flood insurance rate maps for individual properties, which will identify the flood zone designation(s) for those properties. Follow these steps to make a FIRMette for your property.
  • FEMA flood zone designations and historic maps are available online through the FEMA Map Service Center.
How Flood Risk Designations Are Assigned
FIRMs are based on flood insurance studies of specific areas. These studies incorporate a minimum of ten years of data on the frequency, sizes, and locations past floods to determine the probability that a flood of any size will be equaled or exceeded in a year. 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.

The delineation of certain areas on Snohomish County’s adopted FIRMs is based on studies that have been completed as many as 20-30 years ago. New Digital Flood Insurance Rate Maps (DFIRM) incorporating some more recent studies are awaiting adoption pending FEMA’s resolution of a methodology for incorporating the effect of levees.

Please contact Surface Water Management at 425-388-3464 regarding the most up-to-date information on the flood history of your neighborhood.

How Flood Risk Designations Can Be Changed
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.

If you are a homeowner and believe your property is not located in the designated 100-year floodplain [also known as a 1-percent-annual-chance floodplain, or Special Flood Hazard Area (SFHA)], as shown on the effective Flood Insurance Rate Map or Digital Flood Insurance Rate Map for your community and you would like FEMA to make an official determination regarding the location of your property relative to the SFHA, you may request a Letter of Map Amendment (LOMA) or a Letter of Map Revision Based on Fill (LOMR-F). Please see the following two links for more information: