Flood Hazard Mapping

All waterways and bodies of water are subject to flooding – a condition that occurs when the volume of water exceeds the capacity of the waterway channels or when tidal waters are pushed inland by coastal storms.   Flooding can also occur in localized low spots, even if the area is not adjacent to a body of water.

The County of San Diego County Department of Public Works recognizes and manages flood hazard areas that are designated in two ways:

  • Areas identified as vulnerable to flooding from the 1% annual chance flood (100-year floodplain) that are shown on the County’s Flood Insurance Rate Maps (FIRMs) prepared by FEMA’s National Flood Insurance Program (NFIP); and

  • Other flood maps based on studies prepared by the County.  These maps often include areas not studied by the NFIP.

The effective date of the first FEMA Flood Insurance Rate Maps (FIRMs) for the Unincorporated Areas of San Diego County was June 15, 1984.  Since that time, the FIRMs for the County have been updated multiple times, the most recent revision being September 29, 2006.

In addition to the FEMA FIRMs, the County of San Diego has developed its own flood maps that account for additional areas of known risk.  The County flood maps provide 1% annual chance (100-year) riverine flood elevations for areas beyond those studied by FEMA, and are used in conjunction to the FIRM in regulating development.  In many areas, the County floodplain maps overlap the FEMA FIRMs, in these areas, the more stringent of restrictions prevail.  The flood hazard information, including FEMA floodplain boundaries and flood zones as well as areas at risk of dam failure, are depicted on the website for SanGIS. SanGIS is a cooperative endeavor between the City and County of San Diego.  Its GIS data and map creation tools are available free of charge for online use or for purchase for download access and use with other applications.

Back to Main Flood Control Home Page

If you have questions or would like additional information, 
call the County Stormwater hotline at 1(888) 846-0800
or e-mail us at watersheds@sdcounty.ca.gov

Report a Stormwater Violation On-Line

If you see a County storm drainage system in need of maintenance, contact the County Department of Public Works Field Operations staff at (619) 443-1260 weekdays or contact the Stormwater Hotline at 1(888) 846-0800.  For after-hours emergencies contact (858) 565-5262. 

Department of Public Works
Flood Control
5510 Overland Ave., Suite 410, MS O326
San Diego,  CA  92123,  USA
(858) 495-5318           Fax: (858) 495-5263