These changes in Missouri River sediment processes have greatly affected near-shore and riparian habitats important to some native species. As a result, three of these species—two birds (the least tern and piping plover) and one fish (the pallid sturgeon)—are today listed under the federal Endangered Species Act. Changes to the river’s sediment regime also are having impacts on important physical infrastructure. Channel bed lowering, for example, is eroding foundations of flood protection structures in and near Kansas City, and of bridge foundations at many sites along the river and its tributaries. Lower river levels also cause problems at intakes for municipal and industrial water supply systems along the river.
The U.S. Army Corps of Engineers oversees operations of the Missouri River mainstem reservoir system. The U.S. Fish and Wildlife Service issued Biological Opinions in 2000 and 2003 regarding Corps of Engineers projects and operations along the lower Missouri River (USFWS, 2000, 2003). In response to those Biological Opinions, the Corps has been constructing projects along the Missouri River designed to improve habitat conditions for the endangered bird and fish species. Project construction has been accompanied by sediment discharges into the lower Missouri River. Given the location of these Corps of Engineers habitat mitigation projects on lower Missouri River, much of this report focuses on the river’s channelized portion from Sioux City, Iowa, downstream to the confluence with the Mississippi River.
Discharges of sediment from these projects have prompted concerns regarding not only local water quality impacts, but also questions regarding delivery of sediments and nutrients to the Mississippi River delta and the northern Gulf of Mexico. One section of this report thus considers possible downstream effects on water quality into the northern Gulf of Mexico.
Sedimentary processes and sediment management issues are important along the entire length of the Missouri River. For example, large volumes of sediment are trapped in the Missouri River’s upstream reservoirs and represent a substantial portion of sediment no longer available for transport to the Gulf of Mexico. Other sections of the report thus consider sediment processes, and data collection and evaluation systems, for the entire length of the river.
This report is from the National Research Council Committee on Missouri River Recovery and Associated Sediment Management Issues. The study and report were sponsored by the U.S. Army Corps of Engineers. The committee was appointed in 2008 and held five meetings over the course of its project. Public meetings were convened in four Missouri River cities: Kansas City; Omaha; St. Louis; and Vermillion, South Dakota. A final, closed meeting was held in Washington, D.C., in early 2010 at which the committee worked on its draft report.
This report addresses the topics of Missouri River sediment, its physical and biological importance, how its dynamics and roles in the river system