FRESNO, Calif. (AP) — For decades, this city in California's agricultural heartland relied exclusively on cheap, plentiful groundwater and pumped increasingly larger amounts from an aquifer as its population grew.
But eventually, the water table dropped by more than 100 feet, causing some of Fresno's wells to cave in and others to slow to a trickle. The cost of replacing those wells and extracting groundwater ballooned by 400 percent.
"We became the largest energy demand in the region — $11 million a year for electricity just to run the pumps," said Martin Querin, manager of the city's water division, which supplies 550,000 residents.
Fresno is just one player in a water war that's quietly being fought underground. Throughout the Central Valley — one of the world's most productive agricultural regions — farmers, residents and cities have seen their wells go dry. Those who can afford it have drilled deeper wells that can cost hundreds of thousands of dollars.
Experts say water supplies have been strained by growing city populations and massive tracts of newly planted orchards and vineyards.
"Water levels are dropping dramatically in some areas. It's never been this bad," said Steve Arthur, vice president of Arthur and Orum Well Drilling.
The drops create concerns that groundwater is becoming unaffordable and that overuse could cause serious land subsidence, which can damage infrastructure such as roads.
"We can't keep over-pumping groundwater," said Peter Gleick, president of Pacific Institute, a nonpartisan research group in Oakland. "It's simply unsustainable and not economically viable in the long run."
California has few rules governing groundwater. While some basins limit pumping through management plans or court rulings, anyone can build a well and pump unlimited amounts in most of the state.
The U.S. Geological Survey has found in much of California — the San Joaquin Valley, the Central Coast and Southern California — more water has historically been pulled out of the ground than was replenished.