From The Mountain Town News (Allen Best):
To grasp the immensity of the groundwater pumping in California during the last century, think back to the last time you flew into Las Vegas. Before descending into McCarran International Airport, you may have swept across Lake Mead. When full, the reservoir is 112 miles long and up to 532 feet deep. It can hold up 28 million acre-feet of water, or about two average-year flows of the Colorado River before diversions.
That, according to the Los Angeles Times, is how much water has been removed from California’s Central Valley since the advent of groundwater pumping. It’s staggering, the very definition of unsustainable.
Groundwater depletion is a problem not just in California, but across the country. Resources created during geologic timescales are being depleted in human lifetimes for cities and farms. In the United States, 14 percent of all water used to irrigate crops comes from mining groundwater aquifers.
Cheap energy and advances in pumping technology around the end of World War II accelerated this depletion. We have gained the artifice of cheap food and irrigated luxuriance in arid environments. The extraction of water above the rate of recharge is now close to 400 cubic kilometers.
“We are robbing our savings account,” says Andrew Stone, executive director of the American Ground Water Trust. Stone points out that population growth and the uncertain effects of climate change will apply more pressure to these subterranean savings accounts.
It’s not inevitable that we pinch these piggy banks until they’re empty. Los Angeles after World War II turned to groundwater exploitation to satisfy growth. But over time it was able to shift to other mechanisms, including recycling, to meet population needs.
Agriculture regions have been slower to adapt. The Central Valley has been Exhibit A in groundwater mining for many decades. It’s 450 miles up and down and, at a maximum, 60 miles wide and wonderfully productive. One-eighth of total agriculture production in the United States occurs here on 1 percent of the land. From avocados to artichokes, potatoes to peppers, much of your grocery store’s produce likely comes from the Central Valley. “Everyone eats there,” as a headline in the New York Times Magazine noted several years ago.
Snowmelt from the Sierra Nevada provides some of the water for the crops, but aquifers have allowed the great expansion of farming. This is mining, and similar to mining for ores, aquifer pumping can cause the earth itself to subside. One famous photograph taken in California’s Central Valley in the 1970s of a tall telephone pole showed the extent of subsidence, nearly 30 feet at that point.
Soon after that photograph was taken, proposals to methodically address groundwater depletion were laid on the desk of California’s handsome young governor, Jerry Brown. It went nowhere. The issue was too fractious in California then. Only baby steps were taken over the next several decades.
Other states in the West have been more aggressive in adopting state-wide regulation. Colorado’s regulations, for example, were adopted in the late 1960s. They haven’t been a cure-all. Unsustainable extraction of the Ogallala aquifer continues. Denver’s fast-growing southern suburbs, with some of the wealthiest and best-education demographics in the country, depend almost 100 percent on rapidly declining aquifers.
There is no one answer to this unsustainable aquifer mining. Certainly, increased recycling will be one response, as it has been in Los Angeles and soon will be in Denver’s south suburbs. We’ll have to revise our expectations of landscaping, and continue to tinker with how technology can make more efficient use of our supply.
In California, Gov. Brown, now bald and in his 70s, last September signed a trio of laws that together give local jurisdictions tools for planning how to achieve sustainability by 2040. Sustainability here is defined as aquifers recharging, through percolation or direct injection, as rapidly as they are withdrawn. But the laws also reserve a big stick. If local jurisdictions don’t, the state eventually will elbow into local affairs to get the planning done.
Recycling alone can’t alone be the answer for California’s Central Valley or other regions west of the 100th meridian so utterly dependent upon mining of aquifers. Fundamentally, our cheap food, like our cheap energy, is an illusion.
A century ago, hard-rock miners were still making a mess of the West, clawing out high-value minerals and creating the acid-mine drainage, now a significant problem and expense. Ignorance perhaps excuses their actions. With groundwater mining, we have no excuse. We already know we’re on unstable ground.
More groundwater coverage here.