ecological resource of global significance. It provides an array of services to tens of millions of residents and visitors, including drinking water supply, boating, fishing (commercial and recreational), hunting, trapping, tourism, and commercial navigation. Communities, farmers, and tourists all use the river system’s floodplains, which provide sites for settlement, rich soils, and abundant recreational opportunities. These floodplains also experience occasional floods, which entail both costs and benefits. The same flood that threatens levees that protect farm land or communities also increases spawning habitat for fish on un-leveed floodplains. Historical modifications of the river to enhance commercial navigation, and land use changes across the watershed resulting from agriculture, forestry, and urbanization, have fundamentally altered hydrology and habitat. Similarly, actions aimed at ecosystem restoration may affect commercial navigation and other sectors. Sound river management decisions should consider the many values the river system provides, as well as interactions between users. The challenge is to find a balanced program that promotes individual uses while increasing the aggregate value of the Upper Mississippi River and Illinois Waterway to the nation. To its credit, the Corps has creatively expanded its feasibility study over time in an effort to broadly consider these interdependent issues, while also recognizing that the agency has neither the authorities nor the resources to plan and manage all of these issues across the entire UMR-IWW. Nevertheless, many of these uses and sectors are inseparable, and changes or impacts in one sector often affect other sectors. Declines in the value of any of these sectors are of national-level concern. A comprehensive feasibility study will consider these types of interrelations to help manage the system accordingly, and the Corps is correctly attempting to consider some of these relations between sectors.

The Corps of Engineers operates under a large body of authorities, legislative acts, and congressional committee language. This body of directives has accumulated over time without the benefit of any overall strategy or framework. Consequently, new authorities or legislation may be inconsistent with existing directives to the Corps. In instances in which guiding legislation or authorities are contradictory or unclear, the Corps is placed in the position of having to choose which authority or act will be given precedence. Within the context of the UMR-IWW feasibility study and the operations of the navigation system, the Corps considers the 1930 Rivers and Harbors Act that authorized the 9-foot channel project for the Upper Mississippi River as the primary management authority. Although a legal analysis of this situation was beyond the scope of this report, the current situation clearly poses ambiguities for the Corps and confounds the agency’s ability to manage the system in a way that maximizes its value to the nation. Although legislation subsequent to the 1930 Rivers and Harbors Act (e.g.,

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