High Flow Experiments in the Grand Canyon: An Evolving Water Management Paradigm for the Colorado River

Abstract: Historical operations of Glen Canyon Dam have significantly altered the flow of water and sediment in the Colorado River, resulting in numerous ecogeomorphic changes to the Grand Canyon reach. The environmental and recreational impacts of these changes are being addressed to some extent through the release of high flow experiments (HFEs), large-volume, short-duration scheduled releases designed to mimic seasonal flooding aspects of the natural flow regime. This review addresses the evolution of scientific and political thinking regarding the role of HFEs in the management of Grand Canyon resources. Management trade- offs between power, water supply, recreation, and the environment are addressed, as well as the complex physical and ecological responses associated with changes to reservoir operations. The potential to apply lessons learned in the HFE adaptive management process to increasing hydrological uncertainty under climate change is discussed.