On August 16, 2021, the U.S. Bureau of Reclamation announced the first-ever Tier 1 Colorado River shortage. The water delivery cutbacks, which went into effect on January 1, 2022, per the “Colorado River Interim Guidelines for Low Basin Shortages and Coordinate Operations for Lake Powell and Lake Mead” (2007 Interim Guidelines), are most significant for the Central Arizona Project (CAP). Governed by the Central Arizona Water Conservation District, CAP delivers water into Central Arizona for use by tribal, municipal and industrial, and agricultural users. The reason that CAP water users face the most severe cutbacks is because that, in order to secure approval of the 1968 Colorado River Basin Project Act authorizing CAP construction, Arizona had to agree that water delivered through the CAP canal would be junior in priority to California’s Colorado River water deliveries. This means that in deep shortage conditions CAP deliveries could be cut in their entirety before California would experience any cutbacks in water deliveries.