The severe 1973 spring flood in the Mississippi River basin had its beginnings in the mild, wet fall and winter of 1972. Many tributary streams and reservoir levels were well above normal throughout the basin when heavy spring rains begin to fall. Frequent and prolonged warm rains associated with extratropical cyclones and frontal activities fell over large areas of the Mississippi basin in March and April 1973. The cumulative effect of those rainfalls lead to the 1973 Mississippi River basin flood, characterized by its long duration, high volumes of runoff, and large coincident tonnage of sediment transported.