The Colorado River Compact

What It Covers

The Colorado River Compact of 1922 divided 16.4 million acre-feet of water among seven southwestern U.S. states, but flawed measurements, population booms, agricultural overconsumption, and climate-driven snowpack decline have created a water crisis now threatening catastrophic shortages as the 2026 renegotiation deadline passes unresolved.

Key Questions Answered

• •Flawed baseline measurement: The 1922 compact allocated water based on a single hydrological study conducted in Yuma, Arizona, that overestimated flow by roughly 1.5 million acre-feet annually. A competing study by hydrologist Eugene Clyde LaRue was available and more accurate but ignored. States have been drawing approximately 1 million acre-feet per year beyond what the river can supply ever since.
• •Agricultural overconsumption: Residential, commercial, and industrial use accounts for only 20–25% of Colorado River water. The remaining 75–80% goes to agriculture, primarily growing alfalfa and hay to feed cattle. This pattern traces to the 1877 Desert Land Act, which enabled corporations to consolidate desert land cheaply and establish cattle operations that have shaped water policy for over a century.
• •Climate shrinkage: Seventy percent of the Colorado River's flow originates from Rocky Mountain snowmelt. Declining snowpack has reduced the river's annual output to approximately 13 million acre-feet, roughly 80% of 1990s levels. Even the more conservative LaRue estimate of 15 million acre-feet would now exceed actual supply, meaning conservation alone cannot close the gap without structural policy changes.
• •Dead pool risk at Lake Powell: If water levels at Lake Powell drop below the intake penstocks at Glen Canyon Dam, water stops flowing downstream entirely to lower basin states. This scenario, distinct from merely losing hydropower generation, would cut off water supply to cities including Phoenix, Tucson, Las Vegas, and Los Angeles, representing a catastrophic infrastructure failure with no short-term engineering fix.
• •Prior appropriation as federal fallback: If the seven basin states fail to negotiate a new compact, the federal government will likely enforce the prior appropriation doctrine — first in time, first in right — which favors California's oldest water projects over Arizona's newer Central Arizona Project. Arizona, whose population doubled after the Central Arizona Project completed in 1993, faces the steepest mandatory cuts under this default outcome.