Arizona v. California & the Colorado River Compact: Fifty Years Ago, Fifty Years Ahead

Abstract

Hydrologic conditions in the Colorado River Basin have changed markedly in the fifty-year period since the U.S. Supreme Court announced the seminal Colorado River decision of Arizona v. California in 1963. As projected by the Bureau of Reclamation in its recent Colorado River Basin Water Supply and Demand Study, this pattern of change is anticipated to persist during the next fifty years. Water demands exceeded supplies on average in the basin for the first time in recorded history over the past decade, and this supply-demand imbalance is forecast to widen between now and 2060, absent changes in the status quo. Rooted in concerns about reliance interests and expectations attached to Colorado River water in the Lower Basin, this Article considers the nuanced relationship between Arizona v. California and the Colorado River Compact as this relationship is implicated by the supply-demand imbalance. We initially provide an overview of the Compact’s prominent role in the Arizona v. California litigation — notwithstanding the majority’s ultimate disregard of it in the final decision. We then consider Arizona v. California’s facilitation of water uses and losses in the Lower Basin over the past several decades and essential parameters put into place by the Compact that bear on future efforts to manage these uses and losses. We conclude by advocating for the formulation of a Lower Basin water budget that is informed by the Compact’s basinwide apportionment scheme as a means for navigating the supply-demand imbalance.

Keywords: interstate water allocation, interstate compacts, Colorado River Basin, Arizona v. California, water management, water planning, Supreme Court, equitable apportionment