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Missouri Rivers Flood Stages

Missouri is in the heart of the country and spring rains often lead to significant flooding on the Mississippi river and its tributaries. There are four different stages of flooding. At each stage, residents must become increasingly aware of the river's behaviors and of the amount of water flowing from upstream. River floods do not occur unexpectedly as do tornadoes, hurricanes and tsunamis. Nonetheless, the effects of a severe river flood are equally devastating.

The Action Stage
- The action stage in a river's flood cycle requires little action by residents. The action stage is identified by minor flooding but no damage to man-made structures such as buildings, roads and bridges. The river waters may overflow the river banks, but this type of minor flooding is expected each spring.
The Minor Flood Stage
- A minor flood stage is reached when significant amounts of water overflow the river banks and begin to damage nearby housing. During minor flooding, authorities may initiate evacuation procedures or make preparations for evacuations because minor flooding can cut off access to areas of a town. Minor flood damage to buildings includes water damage and foundational erosion, which may require extensive repair once the water recedes.
The Moderate Flood Stage
- The moderate flood stage begins as buildings become inundated with water. The force of flood waters can physically sweep buildings off their foundations. Roads are closed to traffic and residents are not allowed into the affected areas until the water recedes. During a moderate flood in the Mississippi River, tributaries that flow into the Mississippi are known to reverse their flow. The extreme amount of water from the Mississippi flows backward up tributary rivers and creeks as the water seeks to disperse itself.
Major Catastrophic Floods
- The major flood stage is the final level at which significant numbers of residents are evacuated. Local authorities can no longer delay and hope for the waters to crest. Low lying areas such as farmlands can become completely submerged, and extensive flooding causes damage to man-made structures, including bridges, roads and buildings. A major flood is life-threatening and is often called catastrophic. Catastrophic floods are labeled historic, or once in a lifetime, floods that can permanently change a river's course. Major floods that have occurred along the Mississippi and Missouri rivers have crested at water levels nearly 50 feet above the river's normal height.

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