Chapter 25. Preparing for Storms, Flooding, and Water-Related Emergencies
Heavy rain and severe storms can overwhelm storm drains, cause creeks to rise, flood roads, damage buildings, interrupt electricity, and trigger fallen trees or landslides. Flooding may develop gradually during prolonged rain or appear quickly when intense rainfall concentrates in low-lying areas.
Residents of Pleasanton, Dublin, Livermore, San Ramon, Danville, Sunol, and surrounding Tri-Valley and Bay Area communities should understand the drainage conditions near their homes and the roads they regularly use. A street that appears manageable at the beginning of a storm may become dangerous within minutes.
Monitor Weather Alerts
Follow forecasts before a storm arrives and continue monitoring conditions throughout the event. Useful official sources include:
- The National Weather Service
- City and county emergency-alert systems
- Local law-enforcement and fire agencies
- Public works and flood-control authorities
- Caltrans and local transportation agencies
- Local utility providers
Understand the difference between commonly issued alerts. A flood watch means flooding is possible and residents should be prepared. A flood warning means flooding is occurring or expected and protective action may be necessary. A flash flood warning indicates an especially urgent threat that may develop rapidly.
Keep phones charged and enable emergency alerts. Maintain a battery-powered or hand-crank radio because electricity, internet service, and mobile networks may fail. Do not depend exclusively on social-media reports, neighborhood messages, or the appearance of the sky.
Learn How Water Moves Around Your Property
Before the rainy season, observe where water collects and how it drains from the roof, driveway, yard, nearby streets, and surrounding land. Identify low points, slopes, retaining walls, drainage channels, creeks, culverts, storm drains, and areas where runoff has previously accumulated.
Routine preparation may include:
- Cleaning roofs, gutters, and downspouts
- Removing leaves and debris from permitted drainage areas
- Keeping private ditches and drainage paths unobstructed
- Repairing drainage problems before storms
- Moving important possessions above expected water levels
- Protecting documents and valuables in waterproof containers
- Learning whether the property is in or near a mapped flood zone
- Identifying safe evacuation routes toward higher ground
Never enter a storm drain, culvert, creek, channel, or flood-control structure. Do not attempt to remove a blockage while water is flowing rapidly. Report public drainage problems to the appropriate city or county public works agency.
Contra Costa County advises residents to examine where rain pools, understand neighborhood drainage facilities, clean gutters, and keep drains and private ditches clear. Its winter storm preparedness guidance provides additional planning information. Residents should also consult the public works and flood-control resources for their own city or county.
Avoid Low-Lying and Flood-Prone Areas
Underpasses, creek crossings, roadway depressions, parking garages, trails, drainage channels, and roads beside streams may flood before surrounding areas. Become familiar with alternative routes that avoid these locations.
If flooding is forecast, move vehicles and essential property out of low areas before water begins rising, but only when doing so is safe. Never enter a basement, underground garage, or depressed roadway where water is accumulating.
If authorities advise evacuation, leave promptly. Waiting until water surrounds a home may make evacuation impossible and place rescuers at risk. Move toward higher ground and follow official directions rather than choosing a route solely because it is familiar.
Never Drive Through Floodwater
Water across a roadway may be much deeper or faster than it appears. It can conceal washed-out pavement, collapsed shoulders, open manholes, debris, sharp objects, unstable ground, or downed electrical lines.
The National Weather Service warns that approximately six inches of fast-moving water can knock over an adult, while about twelve inches of rushing water can carry away many cars. Larger vehicles, including trucks and SUVs, are not immune. Review the agency’s “Turn Around, Don’t Drown” flood-safety guidance.
When approaching a flooded road:
- Stop well before the water.
- Do not attempt to estimate its depth from inside the vehicle.
- Do not follow another driver through it.
- Never drive around a barricade.
- Turn around and use a safe alternative route.
- If no safe route is available, wait in a safe location and notify someone of your position.
Four-wheel drive, vehicle height, experience, and familiarity with the road do not make moving water safe.
If water rises around a vehicle, circumstances can become life-threatening very quickly. Call 911 and follow the dispatcher’s instructions. Whether it is safer to remain inside or exit depends on water movement, vehicle position, nearby hazards, and access to higher ground; avoid making a hazardous move based on generalized advice when emergency guidance is available.
Do Not Walk Through Moving Water
Floodwater can knock a person down, trap a foot, hide a drop-off, or carry dangerous debris. It may also contain sewage, fuel, chemicals, animal waste, broken glass, and electrical hazards.
Keep children and pets away from creeks, drainage channels, flooded trails, storm drains, culverts, and water-covered streets. Never enter moving water to retrieve property, photograph flooding, or attempt an untrained rescue. If someone is in floodwater, call 911 and provide the most precise location possible.
Ready.gov advises people to move to higher ground, obey evacuation instructions, avoid barricaded roads, and never walk, swim, or drive through floodwater. Review its current flood preparedness and safety recommendations.
Prepare for Power Failures
Storms may bring down trees and power lines or flood electrical equipment. Keep flashlights, batteries, charged power banks, medication, drinking water, shelf-stable food, blankets, and a battery-powered radio available.
Treat every fallen wire as energized. Stay far away and report it to 911 and the utility provider. Do not touch a person, vehicle, fence, tree, or pool of water that may be in contact with a power line.
Never touch electrical equipment while standing in water. Generators must remain outdoors, far from doors, windows, vents, and garages, and protected from rain without restricting ventilation. Never operate a generator inside a home or attached garage. Ready.gov provides additional power-outage safety guidance.
Remain Cautious After the Storm
Water receding from a road or property does not prove the area is safe. Pavement, foundations, slopes, bridges, retaining walls, trees, and utility systems may have been weakened.
Do not enter a flooded or visibly damaged building until authorities permit it. Avoid standing water, photograph damage only from a safe location, and follow official instructions concerning drinking water, food safety, cleanup, mold, and electrical service. Have qualified professionals inspect damaged gas, electrical, structural, and mechanical systems.
Helpful Hint
Never assume a familiar road is safe merely because you have driven it many times. Water can conceal road damage, missing pavement, debris, and dangerous currents. Turn around whenever water covers the roadway.
Important Safety Reminder
Never walk, swim, or drive through moving floodwater. Do not cross barricades, enter drainage channels, touch wet electrical equipment, or approach downed power lines. Move to higher ground and follow current instructions from weather, emergency-management, law-enforcement, fire, public works, and utility authorities.
Important Preparedness and Safety Notice
This chapter provides general preparedness education, not real-time emergency instructions. Conditions, evacuation zones, routes, shelters, road closures, and public-safety directions can change rapidly. During an emergency, consult current information from authorized public agencies and follow all instructions issued by emergency officials. Call 911 for an immediate threat to life, active fire, serious injury, crime in progress, or another urgent emergency.
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