California's Central Valley · California
Central Valley Aquifer
How fast is the Central Valley aquifer being depleted?
Central Valley Aquifer serves about 6.5 million people and underpins roughly $50B of agriculture across California. This model puts its probability of reaching crisis conditions at 17.3% by 2100 (95% CI 16.9%–17.6%), making it a materially at-risk system on the modelled horizon. Expected crisis year is approximately 2068. Measured water levels are falling about 3.07 ft/yr.
Key figures
| Crisis probability by 2040 | 0.906% |
|---|---|
| Crisis probability by 2060 | 6.6% |
| Crisis probability by 2100 | 17.3% (95% CI 16.9%–17.6%) |
| Expected crisis year | 2068 |
| Observed decline rate | 3.0684 ft/yr |
| Latest observed level | 50.03 (2025) |
| Year-to-year volatility | 31.828 |
| Drought persistence φ (AR(1)) | 0.3419 |
| Population served | 6.5M |
| Agricultural value | $50B |
| Modelled annual damage at crisis | $18.25B |
Monitoring wells in this system
Aquifer averages hide local stress. These are the Central Valley wells that appear in the 20 most at-risk sites nationally.
| Well | State | Decline (ft/yr) | P(crisis) 2060 | Expected crisis |
|---|---|---|---|---|
| 017S002W28R007S | CA | 2.71 | 36.2% | 2060 |
| 016S021E33E001S | CA | 1.51 | 0.030% | — |
| 018S002W22E004S | CA | 2.13 | 3.2% | 2070 |
| 018S002W22E003S | CA | 2.02 | 0.060% | — |
| 017S002W28R006S | CA | 2.19 | 5.4% | 2065 |
| 017S002W33D001S | CA | 1.69 | 1.1% | — |
| 017S018E02H004S | CA | 1.67 | 0.0% | — |
| 017S002W33D002S | CA | 1.49 | 0.230% | — |
| 017S002W33D003S | CA | 1.36 | 0.010% | — |
| 017S002W20F001S | CA | 1.04 | 0.0% | — |
How to read these numbers
Crisis probabilities are modelled, not measured: 100,000 Monte Carlo paths per aquifer combining AR(1) drought persistence with CMIP6 warming and demand-supply coupling. Observed decline rates and water levels are measured from USGS monitoring wells. A low aquifer-average probability does not mean local wells are safe — the well table above frequently disagrees with the system average. Full method on the science page, and every input is traceable through the research index.