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Floods are among the most frequent and costly natural disasters, and pose a serious risk to life, property, public health and the economy.  Although the truly devastating floods are most likely in areas with extensive development in floodplains and around levees, like the California Central Valley, all towns and cities are susceptible to flood damage. 

California's rainy season usually lasts from November to April, bringing heavy flooding and increased flood risks with it; however, flooding can happen at any time.  Union City residents, businesses and visitors need to be aware of the possibility and take action in advance to reduce potential damages.

You can check your potential for flood risk (and other hazards) by your address or zip code by clicking on this link, to the California Emergency Management Agency’s Hazard Mitigation Portal.  You can check for up-to-the-minute weather forecasts at the National Weather service, and check for weather alerts from the National Oceanographic and Atmospheric Administration (NOAA) Weather Watches and Warnings site.

General Planning and Preparedness Resources

 What to do Before, During, and After a Flood:

Before a Flood:

  • Avoid building in a floodplain unless you elevate and reinforce your home.
  • Elevate the furnace, water heater, and electric panel if susceptible to flooding.
  • Install "check valves" in sewer traps to prevent flood water from backing up into the drains of your home.
  • Construct barriers (levees, beams, floodwalls) to stop floodwater from entering the building.
  • Seal walls in basements with waterproofing compounds to avoid seepage.  

During a Flood:

  • Be aware that flash flooding can occur. If there is any possibility of a flash flood, move immediately to higher ground.
  • Do not wait for instructions to move.
  • Be aware of streams, drainage channels, canyons, and other areas known to flood suddenly.
  • Flash floods can occur in these areas with or without such typical warnings as rain clouds or heavy rain

If you must prepare to evacuate, you should do the following:

  • Secure your home. If you have time, bring in outdoor furniture. Move essential items to an upper floor.
  • Turn off utilities at the main switches or valves if instructed to do so.
  • Disconnect electrical appliances.
  • Do not touch electrical equipment if you are wet or standing in water. If you have to leave your home, remember these evacuation tips:
  • Do not walk through moving water. Six inches of moving water can make you fall. If you have to walk in water, walk where the water is not moving. Use a stick to check the firmness of the ground in front of you.
  • Do not drive into flooded areas. If floodwaters rise around your car, abandon the car and move to higher ground if you can do so safely. You and the vehicle can be quickly swept away.

**Driving Flood Facts**
The following are important points to remember when driving in flood conditions

  • Six inches of water will reach the bottom of most passenger cars causing loss of control and possible stalling.
  • A foot of water will float many vehicles.
  • Two feet of rushing water can carry away most vehicles including sport utility vehicles (SUV’s) and pick-up trucks.

After a Flood

  • Listen for news reports to learn whether the community’s water supply is safe to drink.
  • Avoid floodwaters; water may be contaminated by oil, gasoline, or raw sewage. Water may also be electrically charged from underground or downed power lines.
  • Avoid moving water.
  • Be aware of areas where floodwaters have receded. Roads may have weakened and could collapse under the weight of a car.
  • Stay away from downed power lines, and report them to the power company.
  • Return home only when authorities indicate it is safe.
  • Stay out of any building if it is surrounded by floodwaters.
  • Use extreme caution when entering buildings; there may be hidden damage, particularly in foundations.
  • Service damaged septic tanks, cesspools, pits, and leaching systems as soon as possible.
  • Damaged sewage systems are serious health hazards.
  • Clean and disinfect everything that got wet. Mud left from floodwater can contain sewage and chemicals.

The Centers for Disease Control and Prevention (CDC) has specific information on what steps should be followed when returning to your residence or business after a flood.   Information is available by clicking on the links below:

Additional Resources: 

  • FEMA Flood Information  - FEMA information as floods are one of the most common hazards in the United States. Flood effects can be local, impacting a neighborhood or community, or very large, affecting entire river basins and multiple states.

  • National Flood Insurance Program  sponsored by the Federal Emergency Management Agency

  • Floodsmart - the official site for the National Flood Insurance Program. Check the risk of flooding in your neighborhood.