FEMA's Flood Zone Maps


The mission of Federal Emergency Management Agency (FEMA) is to support our citizens and first responders to ensure that as a nation we work together to build, sustain and improve our capability to prepare for, protect against, respond to, recover from and mitigate all hazards.

Robert T. Stafford Disaster Relief and Emergency Assistance Act, Public Law 100-707, signed into law November 23, 1988; amended the Disaster Relief Act of 1974, Public Law 93-288. It created the system in place today by which a presidential disaster declaration of an emergency triggers financial and physical assistance through FEMA.  The Act gives FEMA the responsibility for coordinating government-wide relief efforts. It is designed to bring an orderly and systemic means of federal natural disaster assistance for state and local governments in carrying out their responsibilities to aid citizens.

Congress' intention was to encourage states and localities to develop comprehensive disaster preparedness plans, prepare for better intergovernmental coordination in the face of a disaster, encourage the use of insurance coverage, and provide federal assistance programs for losses due to a disaster.  For more information, go to https://www.fema.gov/ or contact the Federal Emergency Management Agency, Region IX at (202) 646-2500. 


A Flood Insurance Rate Map (FIRM) is the official map of a community on which FEMA has delineated both the special hazard areas and the risk premium zones applicable to the community.

The County can determine the relationship of a particular property to the floodplain including:  (1) whether the property is located within the Special Flood Hazard Area; (2) Flood Insurance Rate Map (FIRM) Zone for property; (3) Base Flood Elevation for property, if available; and (4) whether the property is located within the Floodway.  The County also maintains elevation certificates for review, if available.  For further information or assistance, contact San Mateo County Planning and Building Department at 650/599-7310 or 650/599-7311.

Find the Flood Zone for Your Property

  1. You will need the 9-digit APN (0XX-XXX-XX0) for the property.  Property specific information cannot be obtained by entering the address.
  2. Go to the GIS Database.
  3. Enter the APN (leaving out the hyphens) in the box in the top left corner of the screen.  Click “GO”.
  4. Click on the white APN number in the “Features Selected” box once it appears.  Your parcel will be outlined in red.  
  5. In the “Map Layers” box on the right and find the “FEMA Flood Zones” box.  The flood zone is shown in a particular color.  Mouse over this color in an area just outside of the parcel highlighted for the flood zone(s) that apply to the parcel.
  6. To find the description of a flood zone, please find “Description of Moderate to Low and High Risk Areas” on this page.
  7. To find the FEMA Flood Insurance Rate Map (FIRM) Map panel number that applies to your parcel, go to the “Map Layers” box on the right and click on the “FEMA FIRM Panels 2012” box.  The FIRM panel number is displayed when you mouse over the area within the red grid lines containing your parcel.

Find Your Flood Zone »

Hard-copy FEMA FIRM Maps that contain more detailed information specific to each panel area (i.e., base flood elevations) are available for viewing at the Planning Counter. 

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