Dam Failure
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.
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.
Protect Yourself from Dam Failures
What to Do Before a Dam Failure
Knowing your risk, making sure an Emergency Plan 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.
Ways to Plan Ahead
- Know your risk. Do you live downstream from a dam? Is the dam a high-hazard or significant-hazard potential dam? To find out, contact your state or county emergency management agency or visit the National Inventory of Dams (NID) or the Association of State Dam Safety Officials (ASDSO).
- Find out who owns the dam and who regulates the dam. This information also should be available from your state or county emergency management agency, NID, or ASDSO.
- Once you determine that you live downstream from a high-hazard or significant-hazard potential dam and find out who owns the dam, see if a current EAP is in place for the dam. An EAP is a formal document that identifies potential emergency conditions at a dam and specifies preplanned actions to be followed to reduce property damage and loss of life. An EAP specifies actions the dam owner should take to take care of problems at the dam. It also includes steps to assist the dam owner in issuing early warning and notification messages to responsible downstream emergency management authorities of the emergency.
- If there is a dam failure or an imminent dam failure and you need to evacuate, know your evacuation route and get out of harm's way. In general, evacuation planning and implementation are the responsibility of the state and local officials responsible for your safety. However, there may be situations where recreational facilities, campgrounds, or residences are located below a dam and local authorities will not be able to issue a timely warning. In this case, the dam owner should coordinate with local emergency management officials to determine who will warn you and in what priority.
What To Do During and After a Dam Failure
For more information about what to do during and after a dam failure, please visit our flood page.