In a 2011 report, “Agricultural Water Use in California,” a similar group of irrigation experts led by Zoldoske reviewed available data and found that even with increased conservation technology, agriculture could only save about 1.3% more, and that would come at an exorbitant cost.
“We don’t think anything’s changed (between now and then), except we have less groundwater and less surface water,” Zoldoske said.
Part of the disparity may be looking at basin-wide versus individual farm’s water use, he said.
Water that moves below the plant’s root zone underground isn’t really wasted. It typically percolates to recharge the aquifer or flows into a nearby waterway for use downstream. So a conservation practice implemented upstream, such as changing to drip from flood irrigation, will affect users downstream.
As a result, installing drip doesn’t really save water within a water basin, it just changes the dynamics, Zoldoske said.
“Basin-wide (water-use) efficiencies are in the high 90 percents. On-farm levels are all over the place,” he said.
This year most California growers who historically receive surface water from the State Water Project or the federal Central Valley Project were told they would receive none. Growers with wells turned to groundwater to survive. Others left ground fallow or watched permanent crops dry up.
Even before the current drought, the San Joaquin Valley’s groundwater was overdrafted after years of reduced surface deliveries. Ironically, Wade said, the Central Valley Project was constructed in the 1930s and 1940s to help alleviate the valley’s groundwater overdraft.
The solution to California’s drought won’t come easy as water is a complex and politically charged issue. But something more than just talk of enhanced agricultural conservation needs to be done quickly before the nation’s salad bowl wilts and its fruit basket dries up.
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