Flooding and Storm Resources
San Anselmo and Sleepy Hollow Creeks periodically flood. This natural process, caused by the clay soils, topography and climate of the Ross Valley has been exacerbated by human development; undersized bridges and building span the creek, railroad berms across the floodplain, and increased impervious surface throughout the watershed. These are the Town's key messages and flood-related information links.
Current Flood Projects
1. Know your flood hazard
- Find out if your property is subject to flooding. Check out the County's GIS system MarinMap or visit Town Hall to find out if your property is located in the floodplain. Flood risk is described by FEMA maps. 2015 Local Hazard Mitigation Plan Flood Risk Assessment
- Floods can happen anytime, anywhere. To learn more visit FloodSmart.gov and the Ross Valley Flood Protection and Watershed Program- Flood Zone 9
2. Insure your Property from the Flood Hazard
- Flood insurance is mandatory in the Special Flood Hazard Area and if you have a federally backed loan. FloodSmart.gov
- Purchase flood insurance for your home, business, or rental. Visit the FEMA's flood insurance page and click here for more information.
3. Protect People from the Hazard
- Know the flood warning signals. The flood horn sounds when flood is imminent. If you hear 5 blasts, a pause, 5 blasts, a pause and 5 blasts, move away from flood prone areas and seek higher ground. Register at Alert Marin to receive emergency notifications.
- Turn around, don't drown. The Centers for Disease and Control (CDC) report that over half of all the flood-related drownings occur when a vehicle is driven into hazardous flood water. Turn Around, Don't Drown
4. Protect your Property from the Hazard
- Elevate your property and utility equipment above the flood level. Get an elevation certificate to measure your property's susceptibility to flood damage.
List of Elevation Certificates on File
Homeowner's Guide to Retrofitting
- Install flood gates (if applicable). Commercial properties in the floodplain are required to install flood gates to help prevent flooding.
Flood Gate Design
Flood Gate Ordinance
5. Build Responsibly
- Know the requirements for building in the floodplain. Check out the San Anselmo Code 7.11 on Protection of Flood Hazard Areas.
- Get a permit before you build. Contact the Building Department for more information. Floodplain Development Permit
FEMA Guide to Substantial Improvement and Substantial Damage
6. Protect Natural Floodplain Functions
- Keep the creek and other waterways free of obstructions.
Marin County Stormwater Pollution Prevention Program
- Only rain down the drain. It's illegal to discharge chemicals, sediment, trash or other pollutants to our water system. Use best management practices (BMPs) to protect water quality.
San Anselmo Code 5.8 - Runoff Pollution Prevention
National Pollutant Discharge Elimination System (NPDES)
7. General Preparedness
- Develop a family emergency plan. Include evacuation routes, shelter locations, phone numbers, addresses and other important information. Visit Ready.gov/plan for more information.
- Build an emergency kit. Your kit could include water, non-perishable food, flashlight, first aid kit, batteries and other items that would help you survive during a flood or other disaster. Visit Ready.gov/kit for more information.
8. Stay Connected
- Download emergency services and disaster apps for your smartphone. These are helpful apps to use during a an emergency:
National Weather Service
Other Useful Information
- Sand Bag Information
- San Anselmo Flood Committee
- Winter Preparedness Tips
- Town Disaster Preparedness Links
- Ross Valley Flood Protection Tips
- Flood Preparation Tips (UK)
- American Red Cross Safety Library
- After Flood Fact Sheet
- Historical Museum Flooding Webpage
- Town Community Rating System Activities
Floodwaters Carry Contaminants, Prevent Mildew
For more information about flood maps, including inquiries about your building's location relative to the floodplain, you may come to our Town offices during open hours.