Dennis Dimick's National Geographic News article examining ways in which California's drought can get worse, through the irreversible depletion of aquifers, is worrisome reading. It's starting to appear as if California--its culture, its economy--is going to have to change permanently if it is to survive.
Groundwater comes from aquifers—spongelike gravel and sand-filled underground reservoirs—and we see this water only when it flows from springs and wells. In the United States we rely on this hidden—and shrinking—water supply to meet half our needs, and as drought shrinks surface water in lakes, rivers, and reservoirs, we rely on groundwater from aquifers even more. Some shallow aquifers recharge from surface water, but deeper aquifers contain ancient water locked in the earth by changes in geology thousands or millions of years ago. These aquifers typically cannot recharge, and once this "fossil" water is gone, it is gone forever—potentially changing how and where we can live and grow food, among other things.
A severe drought in California—now approaching four years long—has depleted snowpacks, rivers, and lakes, and groundwater use has soared to make up the shortfall. A new report from Stanford University says that nearly 60 percent of the state's water needs are now met by groundwater, up from 40 percent in years when normal amounts of rain and snow fall.
Relying on groundwater to make up for shrinking surface water supplies comes at a rising price, and this hidden water found in California's Central Valley aquifers is the focus of what amounts to a new gold rush. Well-drillers are working overtime, and as Brian Clark Howard reported here last week, farmers and homeowners short of water now must wait in line more than a year for their new wells.
In most years, aquifers recharge as rainfall and streamflow seep into unpaved ground. But during drought the water table—the depth at which water is found below the surface—drops as water is pumped from the ground faster than it can recharge. As Howard reported, Central Valley wells that used to strike water at 500 feet deep must now be drilled down 1,000 feet or more, at a cost of more than $300,000 for a single well. And as aquifers are depleted, the land also begins to subside, or sink.
Unlike those in other western states, Californians know little about their groundwater supply because well-drilling records are kept secret from public view, and there is no statewide policy limiting groundwater use. State legislators are contemplating a measure that would regulate and limit groundwater use, but even if it passes, compliance plans wouldn't be required until 2020, and full restrictions wouldn't kick in until 2040. California property owners now can pump as much water as they want from under the ground they own.