Flooding Maps and Information

Floods are the most common and widespread of all natural disasters–except fire. Most communities in the United States can experience some kind of flooding after spring rains, heavy thunderstorms, or winter snow thaws. Floods can be slow, or fast rising but generally develop over a period of days. Flooding has caused the deaths of more than 10,000 people since 1900. Property damage from flooding now totals over $1 billion each year in the United States. Also significantly, nearly 9 of every 10 presidential disaster declarations result from natural phenomena in which flooding was a major component.

In response to increasing losses from flood hazards nationwide, the National Flood Insurance Program (NFIP) was established. The 1968 Act provided for the availability of flood insurance within communities that were willing to adopt floodplain management programs to mitigate future flood losses. The act also required the identification of all floodplain areas within the United States and the establishment of flood-risk zones within those areas. The following flood maps are a result of this flood plain identification process. More information .

Flood Maps and Information

Source: FEMA, 2009. Digital Flood Insurance Rate Maps (DFIRMS). Except San Mateo County where these maps have not yet been released. In that county, the maps are based on the old FEMA Q3 FIRM maps.
Interactive Flood Hazard Map
California Flood Risk Mapping, Assessment, and Planning – FEMA
Background Information on Flood Insurance Rate Maps
What’s new in flood hazard mapping? – FEMA

Additional Information on Floods

Probability of floods, exposure and vulnerability of the Bay Area to floods
FEMA National Flood Insurance Program
FEMA Homeowner Guide to Retrofitting (pdf) – Six Ways to Protect Your Home From Flooding
Homeowner’s Guide to Flooding – Know what to do if your home is flooded
Ready.gov – Flood
Glossary of Flood Hazard Terms
Last updated: 03.05.2020