This white paper describes how declining runoff and increased consumptive use will impact water supplies and ecosystems, and also considers how these risks can be addressed. The objective of the White Paper is to encourage wide-ranging and innovative thinking about how to sustainably manage the water supply, while simultaneously encouraging the negotiators of new agreements to consider their effects on ecosystems. To achieve this objective, we introduce a wide variety of alternative management paradigms that offer significant modifications or entirely new approaches to the status quo. Because of the magnitude and severity of the impending challenges that the basin faces, we intentionally describe and evaluate approaches that some might consider radical due to existing and assumed physical or management constraints. However, all infrastructural and institutional constraints on the Colorado River have been developed over only the last century, and to assume that decisions must remain bound by such constraints may limit our ability to identify innovative solutions needed to meet the challenges ahead. The goal of this white paper is to encourage conversation and consideration of new management concepts that will better meet future needs.