Flood
Flooding occurs when water overflows onto normally dry land. Flooding can develop quickly and may also trigger mudslides or debris flows, especially in hillside areas or near burn scars.
How This Affects Alameda County
Alameda County experiences seasonal winter storms that can bring heavy rainfall, localized flooding, and landslides.
Flooding may impact:
- Homes and businesses
- Roadways and transportation
- Storm drains, creeks, and low-lying areas
- Utilities and infrastructure
Note: Areas near creeks, hillsides, and burn scars may face increased risk of flooding and debris flows.
To reduce impacts:
- Clear vegetation and debris from gutters and drains
- Inspect trees and remove damaged branches
- Check backflow prevention devices
- Keep storm drains near your property clear
- Store sandbags and materials ahead of storms
Note: If you live near a burn scar or hillside, monitor conditions closely and be prepared to evacuate.
Flood Safety Tips
Before a Flood
- Sign up for ACAlert to receive emergency notifications
- Plan evacuation routes and identify higher ground
- Prepare emergency supplies and important documents
- Know your flood risk and monitor weather forecasts
- Clear gutters, downspouts, and storm drains near your property
- Keep sandbags and plastic sheeting available
Flood Insurance
- Consider purchasing flood insurance, as standard homeowners’ insurance typically does not cover flood damage
- Policies may take time to become active, so plan ahead
Sandbags and Flood Protection
Sandbags and plastic sheeting can help divert water away from buildings and reduce flood damage.
- Obtain supplies early from local hardware or landscaping stores
- Place sandbags before heavy rain begins
- Follow local jurisdiction guidance for distribution locations and availability
During a Flood
- Stay informed through alerts and official updates
- Follow evacuation instructions from local officials if directed
- Move to higher ground if you are in a flood-prone or low-lying area
- Never walk or drive through floodwaters
- Six inches of moving water can knock a person down and one foot of moving water can push a vehicle off the road
- Follow the message: Turn Around, Don’t Drown
- Avoid downed power lines and flooded areas
- Stay away from creeks, storm drains, and fast-moving water
Driving safety:
- Do not drive through flooded roads or around barricades
- Increase following distance in heavy rain
- Turn on headlights in low visibility
After a Flood
- Avoid flooded areas and damaged buildings
- Check for injuries and assist others if safe to do so
- Watch for debris, unstable ground, and downed power lines
- Do not use appliances exposed to water until inspected
- Clean and disinfect areas affected by floodwater
Flood Alert and Warning (National Weather Service)
Understanding alerts help you take action at the right time.
Flood Watch – Be Prepared: are issued when conditions are favorable for flooding. Flooding may occur. Stay informed, monitor conditions, and be ready to take action if the situation changes.
Flood Advisory – Be Aware: are issued when flooding is expected to be minor but may cause inconvenience. Use caution in affected areas, as conditions can still become hazardous if safety measures are not followed.
Flash Flood Warning -Take Action: are issued when a flash flood is imminent or already occurring. Move immediately to higher ground if you are in a flood-prone area. Flash floods can develop quickly, within minutes to hours, and may occur even in areas not currently experiencing rainfall.
Flood Warning -Take Action: are issued when flooding is imminent or already occurring. Take immediate steps to protect yourself and your property and follow instructions from local officials.
Flood Resources
American Red Cross | Flood Safety: Preparedness tips and recovery guidance
FEMA | Flood Map Services Center: Determine if you live or near a flood zone.
FEMA | National Flood Insurance Program: Learn about coverage options and how to protect your property
National Weather Service (NWS) | Flood Safety: Forecasts, alerts, and flood safety guidance
National Weather Service (NWS) | Weather Warnings: Learn how you can receive or monitor NWS Weather Warnings
NOAA | National Weather Prediction Service: Check flood status on dynamic maps to understand your flood risk
Ready.gov | Flood Preparedness: Federal guidance on preparing for and responding to floods