Levees are man-made barriers along a water course constructed for the primary purpose of providing flood, storm and hurricane protection. Even though levees were originally constructed to protect property and reduce damages from flooding, they have often inadvertently increased flood risks by attracting greater development to the floodplain. In fact, many levees built to protect agricultural fields now stand between waterways and large urban communities.
There is no definitive record of how many levees there are in the United States. Based on information from the US Army Corps of Engineers (USACE), the Federal Emergency Management Agency (FEMA), and the State of California, the National Committee on Levee Safety has estimated that there are more than 100,000 miles of levees nationwide. FEMA estimates that levees are found in approximately 22% of the nation's counties and in all fifty states.
Not only are the number and extent of levees unknown, there is no comprehensive assessment of the current condition and performance of those levees. USACE is conducting an inventory and assessment of the levees in its programs, approximately 2,000 levee systems or 14,400 miles of levees. A clearer picture of the condition of these levees will soon emerge — but what of the remaining estimated 85,000 miles or more of levees across the country?
Further, there is currently no national policy related to the safety of levees, and responsibility for levee safety often is assigned in an uncoordinated and incomplete manner, distributed across all levels of government and housed in different agencies. Federal and state agencies have varying policies and criteria concerning many aspects of levee design, construction, operation and maintenance, but there are no national policies, standards or best practices that are comprehensive to the issues of levee safety that can be adopted broadly by governments at all levels. Surveys by the Association of State Dam Safety Officials and the Association of State Floodplain Managers found that only 10 states keep any listing of levees within their borders and only 23 states have an agency with some responsibility for levee safety.