Flood stage is the point at which the surface of a
river,
creek, or other body of water has risen to a sufficient level to cause damage. When a body of water rises to this level, it is considered a
flood event.
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Condition of the river when it rises above a stage predetermined by the Corps of Engineers to be designated as flood stage. Also, the stage at which some part of the main bank may be over flowed, but not necessarily all of it.
(TNDOT1)