FLOOD08661

• County: Statewide
• Basin: Statewide
• Title: Floodplain Web Information
• Date: 11/14/1997
• Prepared For: State of Colorado
• Floodplain - Doc Type: Community File

Learn-Assess

constructed at New Orleans in 1717. Levees are
the most common type of flood control works.
Although they can be effective in reducing flood
losses, a large percentage of private or locally built
levees and floodwalls provide a low level of
protection suitable only for agricultural purposes or
are poorly designed and maintained. Levee or
floodwall overtopping or failure is involved in
approximately one-third of all flood disasters.

Areas behind levees and floodwalls may be at risk
of greater than normal flood damage for several
reasons. Many floodplain residents in those areas
believe that they are protected from floods and do
not think it necessary to take proper precautions.
Development may also continue or accelerate
based on expected flood protection. A levee breach
or floodwall failure, like a dam break, can release a
large wave offlood waters with high velocity.
After a breach, the downstream portion of the
levee system may also act like a dam, catching and
prolonging flooding of the once-protected area.

The Corps has designed and constructed about
10,500 miles oflevees and floodwalls, most of
which have been assigned to nonfederal sponsors
for operation and maintenance after construction.
The Federal Emergency Management Agency has
established minimum design, operation, and
maintenance standards for levees that, for
insurance purposes, must be met in order to be
credited with providing protection against a 1 %
annual probability flood. The Tennessee Valley
Authority owns and inspects 37 saddle dams and
levees and treats them with the same criteria as
regular dams, including inspections,
instrumentation, and maintenance. Thirteen states
have special regulations governing the construction
of levees.

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