California’s aquifers, despite recent rainfall, remain largely unreplenished due to decades of drought and human pumping. A new study reveals that only 25% of lost water has been replenished.
Despite the recent storms that brought immense rainfall to California, the region’s aquifers still haven’t fully recharged after decades of drought and human pumping. A new study reveals that only about 25 percent of the water lost since 2006 was replenished by the storms.
The California aquifer is a massive underground water storage system that supplies about 60% of the state's water needs.
Spanning over 250,000 square miles, it is one of the largest aquifers in the world.
The aquifer recharges through rainfall and snowmelt, which seeps into the ground and renews the water supply.
However, over-extraction and land subsidence threaten the aquifer's sustainability.
Efforts are being made to conserve and manage this vital resource, including implementing sustainable farming practices and promoting water-efficient technologies.
The Impact of Atmospheric Rivers on SoCal’s Aquifers
In 2023, more than a dozen atmospheric rivers brought rainfall to the West Coast, followed by hurricane Hilary in August. The precipitation added over 90 billion gallons of water into surface reservoirs in the Los Angeles area. However, this moisture almost completely recharged the region’s near-surface aquifers, but deeper water-bearing layers hardly gained any relief.
Using Seismic Waves to Track Aquifer Recharge

To assess the impact of the storms on SoCal’s aquifers, a team of researchers led by William Ellsworth at Stanford University used seismic waves to track changes in the aquifers. By analyzing vibrations of different frequencies, they could identify any changes due to water infiltration as deep as hundreds of meters below the surface.
The Limitations of Seismic Sensing
While the technique shows promise, many regions don’t have the large dense networks of seismic instruments that California does. However, researchers might be able to extract useful information from underground fiber-optic networks equipped with the right sensors. This could help improve our understanding of aquifer recharge and groundwater management in areas where data is limited.
A Critical Time for Aquifer Management
The study highlights the importance of effective aquifer management in regions like SoCal, where a significant portion of the water supply comes from groundwater. As the world’s population continues to grow, it’s essential that we prioritize sustainable water management practices to ensure a stable and reliable water supply for future generations.
Aquifers, underground water reservoirs, require careful management to maintain their sustainability.
Over-extraction can lead to land subsidence and decreased water quality.
Effective strategies include monitoring aquifer levels, implementing sustainable pumping rates, and promoting recharge through conservation practices.
Additionally, identifying and protecting vulnerable areas can help preserve these vital resources for future generations.
- sciencenews.org | Even epic rainfall may not be enough to refill SoCal’s aquifers
- strategian.com | Even epic rainfall may not be enough to refill SoCals aquifers ...