Map Shows Where California Is Quickly Sinking Amid US Water Crisis

California's Sacramento Valley is experiencing rapid sinking due to extensive groundwater extraction, raising alarms about water security in the American West, according to a new study. Some areas of the valley floor have subsided by up to 18 inches in a single year during the recent drought, placing strain on one of the nation's most important farming regions.

The Sacramento Valley relies heavily on groundwater during surface water shortages, and during the severe 2020-2022 drought, farmers increasingly tapped underground reserves as surface water levels declined. The study, published in the Proceedings of the National Academy of Sciences, found evidence of accelerated and potentially irreversible subsidence during the recent drought.

Researchers warned that the loss of pore space permanently reduces the aquifer's storage capacity, even if future rains replenish groundwater. Satellite measurements revealed that the aquifer's response to drought was more widespread than previously thought, with large portions of the Sacramento Valley potentially crossing a threshold where the groundwater storage capacity may never be regained.

The study highlights the significance of distinguishing between reversible and irreversible subsidence, as irreversible subsidence affects an aquifer's future storage capacity. Groundwater is a critical backup supply for California's agricultural economy, and the long-term health of aquifers is vital to the region's $45 billion farming industry.

The findings underscore the broader implications of subsidence, as sinking ground can damage infrastructure and increase flood risks.