Report contradicts claims that the state's growers waste water

By TIM HEARDEN

Capital Press

Farmers in the Golden State are more efficient in managing their water supplies than they're sometimes given credit for, researchers at California State University-Fresno assert.

A report from the university's Center for Irrigation Technology disputes any notion that large volumes of "new water" would be available through agricultural water conservation.

In fact, the amount of new water that could be gained only amounts to 1.3 percent of the current amount used by the state's farmers -- and only 0.5 percent of California's total water use of 62.66 million acre-feet, the study found.

"Claims that California farmers are wasteful and inefficient when it comes to managing their water supplies are inaccurate," declares the report, titled "Agricultural Water Use in California: A 2011 Update."

The findings are based on a review of published research and technical data as well as state publications that assess the overall potential for agricultural water-use efficiency to provide new water supplies, according to a university news release.

The findings came as little surprise to Ron Jacobsma, general manager of the Lindsay, Calif.-based Friant Water Authority. The agency oversees Central Valley Project water delivery to 1 million acres of farmland on the east side of the southern San Joaquin Valley.

"We've been looking forward to that coming out for some time," Jacobsma said. "Our experiences being in the San Joaquin Valley are that our guys use water extremely efficiently ... Over half of the 1 million-acre Friant service area is in permanent planting, so we see great investment in high-efficiency irrigation systems there."

While many growers have gone to micro-sprayers and drip irrigation to save water, areas with viable groundwater basins can actually benefit from over-irrigation in wet years depending on the crop's ability to withstand more water, Jacobsma said.

"When you apply water to corn, if it's in excess of the crop's need, some would see it as a waste," he said. "But we know it goes to recharge the groundwater. That's the kind of study the folks at Fresno State took a look at."

The Fresno State irrigation experts' yearlong study aimed to update a 1982 University of California Cooperative Extension report, "Agricultural Water Conservation in California with Emphasis on the San Joaquin Valley," the news release stated. The new study concludes the 1982 report correctly framed the potential for agricultural water-use efficiency.

The new study asserts that groundwater overdraft of about 2 million acre-feet a year continues to be a serious problem in some areas because of inconsistent and uncertain surface water supplies.

Changes such as switching from flood irrigation to drip have the effect of rerouting flows within a basin, but they don't create new water outside of the basin, the report argues.

On-farm conservation efforts can affect downstream water distribution, impacting plants, animals, recreation and human and industrial consumption, the study found.

Online

Agricultural Water Use in California: A 2011 Update: http://www.fresnostatenews.com/wp-content/uploads/cit11-16awureportv2.pdf

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