Levees are widespread and integral to communities in the U.S.
The role that existing levees play in flood risk reduction in communities across the U.S. is significant. Traditional development patterns in the U.S. have focused around rivers and the coast to take advantage of transportation, natural resources and power — many of our larger cities and towns were built in flood prone areas. Nationwide, at least one-third of communities with a population of 50,000 or higher have some portion of their community protected by levees. If you live in a community greater than 1 million in population your chance of having a portion of your community protected by a levee increases to 50 percent. This includes densely populated portions of many of our large cities such as Sacramento, St. Louis, New Orleans, Des Moines, Kansas City, Memphis, and Washington, D.C.
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Levees protect key public infrastructure.
Due to their location, levees very often protect other critical infrastructure from flooding — infrastructure that we rely on not only for every day services such as roads, hospitals and police departments, but more importantly infrastructure that is critical in flood response, evacuation and recovery. When this infrastructure floods, it can mean a community is left cut off from disaster assistance. Flooded power or water plants, located in the less expensive land in the floodplain, can leave a community without water or power for weeks.
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We are reliant on levees — neglecting them places us at risk of catastrophic results.
Flood risk reduction is a complicated formula when it comes to levees and floodwalls. On the one hand, levees and floodwalls can buy time for people to evacuate and move their belongings out of harm's way, there by lessening damage to property and reducing loss of life. On the other hand, over reliance on levees as a front-line of defense, rather than last-line of defense in managing flood risk, has drawn more people to live and work behind levees, intensifying development and increasing consequences should the levee fail or be overtopped. This scenario, when combined with what we know about the condition and aging of our levee systems is a perfect storm for catastrophic failures with significant loss of life and property damage.
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Levees reduce risk — they do not eliminate it.
There are many recent examples of severe flooding impacting communities and entire regions of the U.S. In some cases, levees performed as designed and yet overtopping resulted in extensive damages to property and economic activity. When there are levee failures and unexpected overtopping the damages and loss of life can be much worse.
In the Midwest floods of 2008, flood waters overtopped Cedar Rapids' levees and covered 1,300 city blocks — inundating city hall, the county jail, the fire and police departments, the public library and 3,900 homes. Aware of the impending overtopping, 24,000 people evacuated. Three of the city's four drinking water collection wells were contaminated by murky, petroleum-laden floodwater. That contamination had left only about 15 million gallons a day for the city of more than 120,000 and the suburbs that depend on its water system.
During that same flood event, in the small town of Oakville, Iowa, ninety miles south, the levee unexpectedly failed. Every building in the town was damaged by the 6 feet of water that rushed in. After the floods, two-thirds of its population moved away, leaving just 160 of the 439 residents that called Oakville home before the flood. The bank closed and never reopened. The town lost two-thirds of its tax base, but those who have stayed have resisted suggestions that the town relocate or not rebuild.
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