The Reality Of Ag Water Savings
CSUF Study Shows Conservation Doesn’t Create Significant New Supplies
By J. Randall McFarland, Friant Water Authority
Friant Water Authority leaders are applauding a new academic study that derails the myths 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.
A report on the study released November 16 by the Center for Irrigation Technology at California State University, Fresno validates landmark water efficiency findings in a study conducted three decades ago.
CIT is an internationally-respected research body in the field of water use, management and efficiency on the CSUF campus. Its recent research confirms and builds upon the earlier work and conclusions of Robert Hagan and David Davenport at the University of California, Davis in 1982.
What Agriculture Has Been Saying
“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.”
According to Dr. Zoldoske, “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.”
Santoyo noted that previous reports authored and embraced by environmental organizations have claimed agriculture can conserve 10-15% of its water with those supplies then made available to be redirected to other uses. “That is a fallacy, as this report clearly states,” he said.
Conservation of Only 1.3%
“CIT’s report demonstrates and details that 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. “These 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 CIT shows and is demonstrated in some detail by the study, 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.
CIT’s researchers state, “An important goal of this report is to affirm that the issue is not what total percentage of water agriculture diverts or consumes, it is whether or not agriculture is providing good stewardship over its allocation. As noted earlier, the [Hagan-Davenport] Report was published in part as a response to ’misunderstandings’ that were leading to claims of water wastage within agriculture. These types of claims continue along with reference to solutions that could be quickly or easily implemented.
Water Waste Claims Rejected
“The authors of this paper, as did Davenport and Hagan, reject these claims and explain why based on the principle of recoverable versus irrecoverable fractions.”
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.”
The report also points out the trade-offs that result in largescale farm production within the San Joaquin Valley. “If society wants/needs this mix of food and fiber production, or if the normal flow of business decides in favor of this level of production, then the result is a large volume of consumptive plant water use ¨C evapotranspiration. This is simply a result of the physics of irrigated crop production.”
Percolation and Groudwater
“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 and tens of thousands of rural residents with no other water source for domestic needs. CIT warns repeatedly of the potential for third party impacts if agricultural water use is reduced.”
“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, noting 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.
Ag Water Use Isn’t ’Isolated’
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 codependent and impacted by decisions and activities of the local agricultural water users’.”
The study says, “Water use patterns in the California have developed over decades, especially those involving large storage/delivery projects, resulting in codependent partnerships. Careful analysis must be done to evaluate all impacts before simply calling for increased onfarm water use efficiency. Changes to these environments that result in perceived benefits to some users can also result in negative impacts to other thirdparty users. It is essential to identify and understand these consequences.”
“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.”