Construction of the Glen Canyon Dam in northern Arizona was motivated by the conviction that a river running to the sea is a resource forsaken. Since 1963, it has provided water storage, recreational opportunities, and electricity for millions. It has also generated far-reaching ecological changes, and controlled flooding has been employed since 1996 to restore ecological habitat downriver in the Grand Canyon. The present study situates these high-flow experiments at the Glen Canyon Dam within a neo-Weberian theoretical perspective attuned to a posthumanist critique. The objective of high-flow experiments is to attain greater balance between ecological and instrumental rationalization processes. They are not simply an experiment in habitat renewal but an operational shift signaling a greater resolve to evolve with nature, but they also illustrate the challenges inherent to large-scale ecological restoration. Nonetheless, controlled flooding illustrates important lessons with regard to the need to reflect on, learn from, and adjust socionatural relations in response to ecological degradation and change.