More Elusive Than Ever: Arizona’s Assured Water Supply Protections Under Colorado River Shortages and Groundwater Scarcity

Report | May 2025

Arizona law requires a 100-year assured water supply before selling subdivision lots — an effort to safeguard limited groundwater. For years, developers have relied on the Central Arizona Groundwater Replenishment District (CAGRD) to meet this requirement by replenishing groundwater with Colorado River water. But as river supplies shrink and replenishment demands grow, that system is faltering. Our report, More Elusive Than Ever, examines the cracks in Arizona’s current approach and the urgent need for reform.