… Accounting for ~90% of societal water consumption, irrigated agriculture dominates humanity’s water footprint. Major irrigation districts with substantial water gaps include California’s Central Valley. … In the well-studied California Central Valley, groundwater depletion has been estimated and validated at 7–9 km3/year, with total water storage losses ranging from 10–11 km3/year. Other research reports groundwater depletion at 8.58 km3/year for California, aligning with our estimate of 12.8 km3/year. Similarly, in the extensively studied Colorado River Basin, we estimate unsustainable water consumption at 3.8 km3/year, consistent with previous estimates of 3–4 km3/year.