There are are more than 80,000 dams in the United States, according to the 2007 update to the National Inventory of Dams. Approximately one third of these pose a “high” or “significant” hazard to life and property if failure occurs.
There are fourteen dams which could have a significant impact on Ventura County residents in the event of dam failure. Ten of these dams are in Ventura County and include: Bard Reservoir, Casitas Dam, Lake Eleanor, Lake Sherwood, Las Llajas, Matilija Dam, Runkle Debris Basin, Santa Felicia Dam, Senior Canyon, and Linaloa Lake. The four in Los Angeles County include: Bouquet Canyon Dam, Castaic Dam, Pyramid Dam and the Westlake Reservoir.
Dam failure or levee breeches can occur with little warning. Intense storms may produce a flood in a few hours or even minutes for upstream locations. Flash floods occur within six hours of the beginning of heavy rainfall, and dam failure may occur within hours of the first signs of breaching.
Other failures and breeches can take much longer to occur, from days to weeks, as a result of debris jams or the accumulation of melting snow.
In those cases where flood waters could have a life threatening impact within a short period of time, residents should move to higher ground.
How can I protect myself?
WHAT TO DO BEFORE A DAM FAILURE
Knowing your risk, making sure an Emergency Action Plan (EAP) is in place, and evacuating when directed by emergency response officials are the most important steps you can take to staying safe from a dam failure.
Be prepared to respond to a dam failure/flooding by taking the following actions:
- Assemble emergency supply kits for your home, workplace, and vehicle.
- Store the following materials for protecting your home in a location away from potential flooding: sandbags, plastic sheeting, plywood, and lumber.
- Teach children not to play in or nears rivers, streams, or other areas of potential flooding.
- Maintain fuel in your cars; electrical outages might make gasoline pumps inoperable.
- Identify safe routes from your home or work place to high ground. Determine whether you can use these routes during flooding or storms.
- Clear debris and overgrowth from gutters and storm drains.
- Notify your local department of public works about debris and overgrowth in public drainage facilities.
- Work with neighbors to solve potential drainage problems and to avoid diverting debris onto their properties.
WHAT TO DO DURING A DAM FAILURE
If a flood is likely in your area, you should:
- Listen to the radio or television for information.
- 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-ups.
WHAT TO DO AFTER A DAM FAILURE
The following are guidelines for the period following 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.