California showing signs of groundwater exhaustion

The huge reservoir of water under the soil surface is typically the place where California farmers turn during droughts, when surface water becomes scarce. After three years of drought and persistent groundwater use for water-intensive crops, the water table is dropping steadily, reported Todd Frankel in the Washington Post.

The aquifer accumulated over thousands of years, but is now dropping as much as two feet per year in some parts of the Central Valley. As the water is pumped, the ground sinks down too, said Thomas Harter, UC Agriculture and Natural Resources Cooperative Extension hydrologist based at UC Davis. When the soil compresses, groundwater can never be fully recharged again.

Harter said the state's groundwater reserve reached historic lows last year.

“With little recharge, many areas are currently at the lowest recorded levels ever,” Harter said. “It's worrisome.”

Last year, state lawmakers passed California's first extensive groundwater regulation, allowing for the creation of local boards to oversee how the water is used. But it will take up to two decades before the new law takes full effect.