A dam is an artificial barrier that impounds water, wastewater, or any liquid-borne material for the purpose of storage or control of water (different types of dams). Dams can fail suddenly, with very little warning. Flooding is the most likely result of a dam failure. Knowing the risk of dam failure and planning in advance can reduce the risk of serious injury or loss of life.
Dam Failure Information
There 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.
Intense storms may produce a flood in a few hours or even minutes for upstream locations. Flash floods occur within 6 hours of the beginning of heavy rainfall, and dam failure may occur within hours of the first signs of breaching. Other failures and breaches can take days and weeks to occur because of debris jams or the accumulation of melting snow.
For preparedness tips on what to do before, during, and after a flood, visit Ready.gov.