Damage Control: Restoring the Physical Integrity of America’s Rivers

Abstract

Technological development of America’s rivers, including the installation of more than 80,000 dams, has segmented the streams and fragmented their watersheds. A vision for the nation’s rivers requires science and public policy that emphasize restoration and maintenance of the rivers’ physical integrity to create a great river legacy for future generations. The Clean Water Act mandates the biological, chemical, and physical integrity of the nation’s rivers, but researchers and decision makers have paid scant attention to physical integrity. Physical integrity for rivers refers to a set of active fluvial processes and landforms wherein the channel, near-channel landforms, sediments, and overall river configuration maintain a dynamic equilibrium, with adjustments not exceeding limits of change defined by societal values. Rivers with physical integrity have functional surfaces and materials that are susceptible to monitoring and measurement with a set of geographic indicator parameters. Science and policy for the nation’s rivers must blend watershed principles with ecosystem concepts, focus on change rather than equilibrium as a defining characteristic of streams, adopt probabilistic rather than exclusively deterministic approaches, and pursue geographic representativeness through hydrodiversity, geodiversity, and biodiversity. The dams that fragment the system also offer opportunities for restoration of some natural characteristics through adjusted operating rules, redesign, and physical renovation, along with the removal of some dysfunctional structures. In the near future, when social values for rivers are likely to revolve around protection for endangered species, economics of flood protection, and dam removal issues, we can enhance restoration efforts by including physical integrity in research agendas, policy decisions, operational rulemaking, and public debate. Our multicentury legacy for future generations can and should be to establish physical integrity for rivers that are as natural as possible, thus insuring that as a system they are parts of the infrastructure for a vibrant national economy, continuing threads of our cultural heritage, and quality natural environments.