Talk of enhanced ag water conservation is all wet - The Packer

Talk of enhanced ag water conservation is all wet

07/11/2014 09:46:00 AM
Vicky Boyd

Vicky Boyd, staff writerVicky Boyd, staff writerEvery now and then — and particularly during a drought — some group issues a report that says if only California agriculture would conserve a little more, all of the state’s water woes would be solved.

But Mike Wade, executive director of the Sacramento-based California Farm Water Coalition, takes exception to that.

“Conservation and recycling are important, but we can’t conserve our way out of the existing situation with the current demands,” he said.

Instead, he and numerous agricultural groups within the state have been pushing for years for new storage facilities to capture runoff before it flows to San Francisco Bay.

The most recent report, “The Untapped Potential of California’s Water Supply,” was released June 10 and penned by the Oakland-based Pacific Institute and New York-based Natural Resources Defense Council. It says a blend of conservation, recycling and capturing storm water runoff could save 14 million acre-feet annually.

By using modern irrigation technologies, such as drip irrigation and irrigation scheduling, the groups say agriculture could cut water use by 17% to 22%. In other words, these measures could free up 5.6 million to 6.6 million acre-feet of ag water annually.

Everybody can do a better job conserving water, and agriculture is no exception. But if the industry were truly wasting roughly 6 million acre-feet of water annually, as the report claims, where is it going?

That’s the question David Zoldoske, director of California State University, Fresno’s Center for Irrigation Technology, has posed. “Over 10 years, that’s 60 million acre-feet, and that’s kind of hard to hide.”

This so-called “wasted” water hasn’t gone into aquifer recharge because groundwater overdraft is more than 2 million acre-feet annually, according to the U.S. Geological Survey. And it isn’t in rivers, because stream flows are at record lows, according to the Department of Water Resources.

Wade pointed to similar reports the Pacific Institute released in 2008 and 2009 that focused on how agriculture could save 17% of its water use by adopting irrigation technology, irrigation scheduling and regulated deficit irrigation.

In a 2008 commentary, a group of irrigation experts — including Zoldoske and Charles Burt, chairman of Cal Poly, San Luis Obispo’s Irrigation Training & Research Center — poked holes in one of the institute’s reports.

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.

vlboyd@thepacker.com

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