Occurrence and transport of nutrients in the Missouri River Basin, April through September 2011

The character of the 2011 Missouri River flood in the lower part of the basin was different from other floods during the last 30 years. Floods on the lower Missouri River generally are characterized as muddy from erosion of soils. In contrast to the historic flood of 1993, much of the Missouri River floodwater downstream of Sioux City, Iowa originated from snowmelt and rainfall in the upper and middle parts of the basin. Runoff from this area of predominantly forest, prairie, and wheat farming is "cleaner water" with smaller amounts of suspended sediment and dissolved and particulate nutrients. Flood water in 2011 contained less sediment and dissolved nitrate than in the 1993 floodwater. First hand observations made by long-time U.S. Geological Survey hydrologic technician, Joe Gorman, and reported by David Hendee in the Omaha World Herald describe the character of the 2011 Missouri River flood.