More than a third of our nation’s dams are already 50 years old. About 14,000 of those dams pose a “high” or “significant” hazard to life and property if failure occurs. There are also about 2,000 “unsafe” dams in the United States and in almost every state. So, while dams are built not to fail, they do.
Dams can fail with little warning. Intense storms may produce a flood in a few hours or even minutes for upstream locations. Flash floods can 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 breaches can take much longer to occur, from days to weeks, as a result of debris jams, the accumulation of melting snow, build up of water pressure on a dam with (unknown) deficiencies after days of heavy rain, etc. Flooding can also occur when a dam operator releases excess water downstream to relieve pressure from the dam.
The risk for dam failure and the potential catastrophic damage it can cause are not shown on the flood maps from the Federal Emergency Management Agency (FEMA). So, while property owners may be aware that they live downstream from a dam, they may not be aware of the true risk. Property owners should consider financially protecting their home, business and/or contents with flood insurance. Many of these homes and businesses may qualify for the low-cost Preferred Risk Policy, with premiums starting as low as $129 for a home and its contents.
There is typically a 30-day waiting period for a policy to become effective, so don’t wait until the next heavy rain.