Study finds farmers efficiently use water

Claims that California farmers are wasteful and inefficient in managing their water supplies are inaccurate, according to a new report released by the Center for Irrigation Technology (CIT) at Fresno State University.

The report “Agricultural Water Use in California: A 2011 Update” also refutes assertions by some that large volumes of “new water” would be available through agricultural water conservation.

The findings are based on a thorough review of published research and technical data as well as state of California publications to assess the overall potential for agricultural water-use efficiency to provide new water supplies. The report found that little potential exists for new water unless large swaths of agricultural land are taken out of production, which technically is not water-use efficiency

Friant Water Authority leaders in Lindsay applauded the study.

 that details the fallacy of claims that agricultural water conservation can result in enough new water to solve the problems of water management or at least provide the volumes of water desired by all users.

“We are very pleased to see that such an esteemed research group has validated much of what those of us involved in delivering and utilizing agricultural water supplies have been saying for decades,” said Friant Water Authority Assistant General Manager Mario Santoyo.

“Agriculture’s water use efficiency has increased dramatically over the past 20 years and there is no evidence that conservation we’ve achieved is sufficient to create significant additional water supplies for others. We agree with what Dr. David Zoldoske, the CIT’s Director, said in introducing the study.”

CIT Director Zoldoske said, “The study is an important addition to the ongoing discussions about California water and specifically what decisions must be made to assure adequate supplies for the future. The information presented in this paper should provide a valuable tool in moving the discussions forward.”

Among the study’s key findings:

- The estimated potential new water from agricultural water-use efficiency is 1.3 percent of the current amount used by the state’s farmers – about 330,000 acre-feet per year. That represents about 0.5 percent of California’s total water use of 62.66 million acre-feet.

- Groundwater overdraft of about 2 million acre-feet per year continues to be a serious problem in certain regions of California because of inconsistent and uncertain surface water supplies.

- Changes in irrigation practices, such as switching from flood irrigation to drip, have the effect of rerouting flows within a region (or basin) but generally do not create new water outside of the basin.

- Previous reallocations of agricultural water supplies for environmental purposes represent 5.6 percent of farm-water diversions.

- On-farm conservation efforts can affect downstream water distribution patterns, with potential impacts on plants and animals, recreation, as well as human and industrial consumptive uses.

“CIT’s report demonstrates agricultural conservation would account for just 1.3% of existing farm water supplies and only 0.5% of the state’s total water use,” Santoyo said. “Those are tiny amounts statewide, adding up to what CIT estimates as being 330,000 acre-feet each year.” The report also shows that previous reallocations of agricultural water supplies for environmental purposes now add up to at least 5% of farm water diversions depending on the water year.

Experience since Central Valley Project water deliveries began in the Friant Division along the San Joaquin Valley’s East Side in the mid to late 1940s agrees with what the CID study shows, Santoyo said. “Changes in irrigation practices create opportunities to use the saved water within the region, such as through transfers, but have not resulted in new supplies beyond the Friant Division,” he said.

Friant Water Authority General Manager Ronald D. Jacobsma pointed out CIT’s study “demonstrates a clear and well-defined trend toward dramatic improvements in water management and efficiency. The study shows that between 1994-2008, drip irrigation use on California’s 8 million irrigated acres increased by 150%, from 933,696 acres to 2,336,130 acres. The increase in drip irrigation and water use efficiency through the farmland irrigated from the Friant-Kern and Madera canals is even greater.”

“Something else we have long known that has been validated by the report is that water applied to a crop but not actually used by the plant is not lost but typically percolates into the ground and helps boost groundwater supplies,” Jacobsma said. “Groundwater is relied upon not only by thousands of farmers but many scores of communities that have no other water source for domestic needs.”

“As for switching to a crop that takes less water, it isn’t that easy,” said Santoyo. He said the CIT study is correct in pointing out that farm markets and economics, increased expenditures for field preparation and equipment, soil types and many other crucial factors must all be considered.

Santoyo also said the new study also “corroborates Friant’s experiences in conjunctively using groundwater and surface water, pointing out that preservation of groundwater supplies is impossible if surface water supplies are inadequate or disrupted.” The report notes that a serious overdraft problem, now amounting to some 2 million acre-feet annually across the state, will continue if surface water supply and reliability do not improve.

He said that it “is important to note the report’s conclusion that farm water use isn’t some isolated activity that takes place but that it’s an integral part of what the report calls ‘local and regional environments that are often co‐dependent and impacted by decisions and activities of the local agricultural water users’.”

“Friant’s farmers know and understand what this report states,” Jacobsma added, “that to be viable, any big changes have to be founded on assessments and analysis by the people who know the local conditions best – the farmers themselves.”

“We’re encouraged that CIT finds it is strongly evident that major findings of the Hagan-Davenport Report that resulted from an extensive water efficiency study nearly 30 years ago stand,” Santoyo said. “We all know that what CIT says is true – that today’s water issues go well beyond what Robert Hagan and David Davenport studied, but the basis of their work has been found to be just as relevant now as it was in 1982. Much of what critics of agricultural water use claim is being wasted is actually used again by other farmers and communities.”

The study is the culmination of a yearlong effort by irrigation experts at the Center for Irrigation Technology to update the 1982 University of California Cooperative Extension report “Agricultural Water Conservation in California with Emphasis on the San Joaquin Valley” by David C. Davenport and Robert M. Hagan.

The new study concludes that the 1982 report correctly framed the potential for agricultural water-use efficiency, and many of its findings are still relevant 30 years later.

The complete report and its findings can be found at www.californiawater.org.

Created in 1980, the Center for Irrigation Technology is internationally recognized as an independent testing laboratory, applied research facility and educational resource. One of California’s biggest challenges is managing ever-increasing demands on its most precious resource – water. A core mission of CIT is to help extend this limited supply of water through the use of technology, research and education.