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Heavy Rain



Dams are an important resource in the United States, providing many functions, including recreation, flood control, irrigation, water supply and hydroelectric power. Dams range from massive concrete structures to more local earthen structures, such as those near a farm's pond. Surprisingly, very few dams are owned by the federal government; in fact almost two-thirds are privately owned. While it is the dam owner's sole responsibility for the safety and liability of the dam should something happen, the states have regulatory responsibility for about 90% of the 84,000 plus dams in the National Inventory of Dams.

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.

Flooding From Dams & What You Can Do

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.

There is typically a 30-day waiting period from date of purchase before your policy goes into effect, so don't wait until the next heavy rain. For more information about dams and the risk of living downstream from them, visit:

Live near a dam

Dams can fail with little warning, and the damage can be catastrophic. Find Out More

1 An "unsafe" dam is defined by most states and federal agencies as one that has been found to have deficiencies that leave it more susceptible to failure. Source: American Society of Civil Engineers.
2 Premium is for rates effective January 1, 2011.

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For flood insurance rating purposes, a primary residence is a building that will be lived in by the insured or the insured's spouse for at least 80 percent of the 365 days following the policy effective date. If the building will be lived in for less than 80 percent of the policy year, it is considered to be a non-primary residence.

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Last Updated: Thursday, 19-May-2016, 3:20 PM (EDT)

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