Even scarier than California’s shrinking reservoirs is its shrinking groundwater supply – 15 to 20 percent of U.S. groundwater is coming from the Central Valley alonePosted by Jim at Sunday, March 29, 2015
By Colleen Shalby
20 March 2015
(PBS) – Last week a startling headline on California’s dire water supply fueled a wave of reports that the state was on borrowed time: “California has about one year of water left. Will you ration now?” read the Op-Ed that first appeared in the Los Angeles Times. Several other news outlets picked up the story.
But Jay Famiglietti, JPL scientist and author of the Op-Ed that sparked the coverage, said while the problem is indeed serious, many of the headlines didn’t quite get it right. That California’s reservoirs hold only a year’s worth of water is true, but somewhat beside the point. Most concerning, he says, is what’s happening to the state’s groundwater supply.
California’s reservoirs, he said, typically store about three years of water at a time. Sure, with the state’s severe drought, the amount now is less than ideal. But far more water exists underground.
Groundwater comes from aquifers — water that’s stored beneath the Earth’s surface in the pores of soil and the cracks of rock and granite. And in California, which is entering its fourth year of drought, there’s no current management plan to sustain that reserve, Famiglietti said.
Think about it this way, he said. Reservoir water is your checking account, and groundwater is your money in the bank. Some goes into your checking, but most exists in your savings account. Rainfall and snow is your monthly income.
Essentially, the state is depleting its primary funds.
“If you can live check-to-check on rain and snowmelt, that’s great. But [California] can’t. We haven’t really ever done that.”
Where’s the groundwater going?
Since 2014, only 25 percent of California’s water supply has come from surface water: that includes reservoirs, lakes, streams and rivers. Prior to 2011, when the state officially declared drought, that surface water made up two-thirds of the state’s supply. Groundwater now makes up a full 75 percent of California’s total supply, up from one-third.
But with a shortage of surface water due to drought, farmers in the Central Valley are pumping out groundwater to irrigate their crops, said Claudia Faunt, program chief for Groundwater Framework and Applied Modeling at U.S. Geological Survey.
She estimates that 15 to 20 percent of the nation’s groundwater is coming from the Central Valley alone. The region is the source of roughly 25 percent of the nation’s table food.
Less water means less produce. And less produce could eventually force the U.S. to import products that are California staples, such as almonds and pistachios.
Without sufficient access to surface water, Faunt says those farmers are forced to drill new wells for irrigation.
This threatens more than just supply. Groundwater extraction can cause subsidence, or sinking, of the land above the aquifers. And that can lead to breaks in infrastructure like roads and buildings, and the buckling of canals. [more]