The allocation of water along the Colorado River have long been known to exceed renewable supplies. Since the turn of the century, the storage in the reservoirs began to precipitously decline, falling from 93% full in 1998 to 23% full in 2023, putting the lifeline of 40 million people, vast agricultural production, and two major hydropower facilities at risk. Throughout that period, overallocation, the onset of a ‘Millenium Drought’, and climate change coalesced to force water users to agree to incremental use reductions in the USA and Mexico, however, all the existing agreements expire in 2026. An intense renegotiation process is underway that will shape the next 20-30 years of the river. Concepts of Decision Making under Deep Uncertainty (DMDU) have been embraced by the US Bureau of Reclamation as they push seven Basin States to reach an elusive agreement on how to reduce uses far beyond anything fathomable to date. This seminar will provide an explanation of this ongoing process and a reflection on the most significant application of DMDU to date.