The Missouri River Ecosystem: Exploring the Prospects for Recovery resulted from a study conducted at the request of the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers. The nation's longest river, the Missouri River and its floodplain ecosystem experienced substantial environmental and hydrologic changes during the twentieth century. The context of Missouri River dam and reservoir system management is marked by sharp differences between stakeholders regarding the river's proper management regime. The management agencies have been challenged to determine the appropriate balance between these competing interests. This Water Science and Technology Board report reviews the ecological state of the river and floodplain ecosystem, scientific research of the ecosystem, and the prospects for implementing an adaptive management approach, all with a view toward helping move beyond ongoing scientific and other differences. The report notes that continued ecological degradation of the ecosystem is certain unless some portion of pre-settlement river flows and processes were restored. The report also includes recommendations to enhance scientific knowledge through carefully planned and monitored river management actions and the enactment of a Missouri River Protection and Recovery Act.