Jefferson County - East-West Gateway Coordinating Council

A Regional Overview All-Hazard Mitigation Plan 3
FIGURE J14 FIGURE J15
Satellite image of flooding at Aerial photo along the Mississippi River 1993
Missouri/Mississippi River confluence.
Background
The first step to floodplain management as a nonstructural alternative to flood control was
incorporated into the National Flood Insurance Act of 1968. This was 40 years after the
Flood Control Act of 1928 that authorized the United States Corps of Engineers (USACE) to
control the Mississippi River with dams, levees and diversion channels. This Act authorized
the USACE to undertake a structural approach to reducing flood damages (thus keeping
water from people). After numerous floods, and having spent billions of dollars on floods
and disasters, Congress looked at another approach to reduce flood losses, adding a nonstructural
approach in the National Flood Insurance Act of 1968. This act, called the
National Flood Insurance program (NFIP), required local governments to adopt regulations
governing new development activities in identified flood plains in order to be eligible for
the sale of flood insurance within their jurisdictions.
Description of Hazard
Flooding is a natural event and has been characteristic of rivers throughout history. It
becomes a disaster when it is of such magnitude that both man-made and natural
landforms and human lives are destroyed or seriously damaged (Gaffney). Through
analysis of existing federal Flood Insurance Rate Maps (FIRM) and Flood Insurance Studies,
the Hazard Mitigation Plan Unit of EWG has determined that the counties included in the
EWG planning region including St. Louis County, St. Charles County, Franklin County,
Jefferson County and the City of St. Louis have 100-year floodplains (in addition to 500year
floodplains) and may be affected by flooding hazards. A variety of factors affect the
type and severity of flooding throughout the planning region, including urban
development and infrastructure and topography.
A flood is defined as an overflow or inundation that comes from a river or other body of
water (Barrows, 1948) and causes or threatens damage or any relatively high streamflow