Dear Tom,
I live on the DesPlaines River. How is the “flood stage” of a river defined?
Martha Wilmerson

Dear Martha,
It is widely believed that flood stage is the point at which water begins to overflow the banks of a river. However, this is not necessarily true. Actually, flood stage is the point at which overflow of the natural banks of a river or stream first begins to present a potential flood damage hazard to the area. Therefore, it does not solely depend on the level where water leaves its banks. In many instances, flood stage may actually be several feet above bank full because no significant property damage occurs until the water level reaches a higher stage. Input from local officials and emergency managers is used to set flood stage thresholds.