Using Multi-Objective Management to Reduce Flood Losses in Your

MINIMUM NATIONAL FLOODPLAIN REGULATION REQUIREMENTS
The National Flood Insurance Program is administered by the Federal Emergency Management
Agency. As a condition of making flood insurance available for their residents, communities that
participate in the program agree to regulate new construction in the base floodplain.
There are four major floodplain requirements; additional regulations may be set by state or local law.
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All development in the base floodplain must have a permit from the community.
“Development” is defined as any human-made change to the land, including new buildings,
improvements to buildings, filling, grading, mining, dredging, etc.
Development should not be allowed in floodway. The floodway is the channel and central
portion of the floodplain that is needed to convey the base flood. It is usually the most
hazardous area of a riverine floodplain and the most sensitive to development. At a minimum,
no development in the floodway can cause an obstruction to flood flows. An engineering
study is usually needed to see if this will happen.
New buildings may be built in the floodplain, but they must be protected from damage by the
base flood. The lowest floors of residential buildings must be elevated to or above the base
flood elevation. Nonresidential buildings must be elevated or floodproofed. Because of the
restrictions described above, buildings that are built in the floodplain are usually located
outside the floodway.
When an addition, improvement, or repair of damage to an existing building is valued at more
than 50% of the value of the original building, than it is considered a substantial improvement.
A substantial improvement is treated as a new building.
Communities are encouraged to adopt local ordinances that are more comprehensive or provide more
protection than the state or federal criteria. This is especially important in areas with older maps that
may not reflect the current hazard. Stricter standards could include prohibiting certain damage-prone
uses from the floodway or requiring structures to be elevated one or more feet above the base flood
elevation.
Watershed planners can identify the most effective location for a detention
or retention basin. The community then can require developers to contribute funds
for a regional basin in lieu of constructing on-site detention. Some state and
regional agencies have stormwater standards that all communities and developers
must follow. In some places, stormwater projects are funded with utility or user
fees. Each property in the watershed pays according to the amount of runoff it
generates.
Best management practices−Best management practices (BMPs) reduce
nonpoint source pollutants that enter the waterways. Nonpoint source pollutants
are those carried by stormwater. They include lawn fertilizers, pesticides, farm
chemicals, and oils from street surfaces and industrial areas.
Many measures that combat nonpoint source pollution also yield flood
protection benefits. For example, one of the most important nonpoint source
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