No, Almonds Don't Use 10 Percent of California's Water

Posted February 14th, 2015

The author of the article addressed in this post has since revisited his numbers and made some important correction. Click here for more information about that correction.

Do almonds use 10 percent of California’s total water supply? The short answer is no.

This myth, which we’ve heard a few times in the media, seems to trace back to a Slate article from last May. Its author generally engages in a thoughtful and nuanced discussion of California’s water use. He notes that almonds are an important economic contributor in the state and that all foods require water, including some that are far more water intensive than almonds.

Unfortunately, in the months since the original post, others have ignored those parts of the Slate article while repeating one this one claim which doesn’t…shall we say…hold water. 

Here’s what the author says:

California as a whole diverts or pumps 43 million acre-feet of water each year to supplement its meager rainfall. In total, agriculture consumes 34 million acre-feet of that. (An acre-foot is just what it sounds like: the amount of water needed to cover an acre of flat ground up to a foot, or about 325,000 gallons of water.) In 2013, there were 940,000 acres of almonds in California, according to the USDA (PDF). Each acre of almonds uses three to four acre-feet of water each year…Almonds alone use about 10 percent of California’s total water supply each year…

Water requirements vary by tree age and some other factors, but to give Slate the benefit of the doubt, let’s use the high end. That would be 4 acre-feet/acre x 940,000 acres = 3.76 million acre-feet. That’s an overestimate (keep in mind that more than 100,000 of those acres are not mature trees, so they require far less water) and it’s still not 10 percent of 43 million acre-feet. 

But that’s just the tip of the iceberg when it comes to the problems with this calculation.

First: 43 million acre-feet of water is not California’s “total water supply.” In fact, from 2001 to 2010 (the most recent data available from the Department of Water Resources), the state’s total managed water supply averaged more than 80 million acre-feet.1 California’s managed water supply is divided among three sectors: urban, agricultural, and environmental uses. Generally speaking, environmental use – things like managing wetlands and protecting various species of fish – is the largest of the three. That water is managed by humans – including through pumping and diversion – much like urban and agricultural water. According to the Public Policy Institute of California, environmental use represents about 50 percent of the state’s total supply on average.  But it’s left out of the author’s calculations completely.  Accounting for environmental water as about half of the state’s total supply turns “less than 9 percent” into “less than 4.5 percent.”

Second: there’s no question that California is in the midst of an historic drought, but that doesn’t mean we should ignore the role rainfall altogether. According to grower information collected through the California Almond Sustainability Program, rainfall accounts for about a quarter of almond tree water needs, on average across the state.  That means, in a normal year, the real amount of California’s water that goes to almonds is closer to 3 percent. The exact number, of course, varies a bit from year to year, but you can clearly see that the 10 percent many have claimed is simply false.

It’s also worth noting that California farmers have steadily done more with less. In the past 40 years, the value of California agriculture has increased by more than 85 percent; during that period, the total California crop-applied water use fell by more than 5 percent.4 Even though the acreage of perennial crops in California, including almonds, increased during the 2000s, the total amount of managed water that went to farms held steady – so a shift in crops grown hasn’t meant more total water going to agriculture.5

California’s water is a precious resource, and the conversation about whether we’re getting good value for it is an important one. But we can’t have an honest conversation if we’re not using accurate information.

We, of course, believe almonds are a good investment for California. Nearly two decades of research shows that almonds can help maintain a healthy heart and cholesterol levels. Their powerful nutrient package also includes 6 grams of plant-based protein, 4 grams of filling dietary fiber, and important vitamins and minerals in every handful.

And almonds aren’t just good for your body – they’re good for California too, adding more than 100,000 jobs and $11 billion to the state’s economy.6  At the same time, we’re constantly working to do more with less. Over the past 20 years, we’ve reduced the amount of water it takes to grow a pound of almonds by 33 percent and we’re not stopping there.7  We continue to research new ways to conserve water, ranging from improved soil management and irrigation practices to longer-term projects like identifying types of trees that can get by with less water.8

In the meantime, we look forward to continuing this critical dialogue.  

*These calculations were based on 2013 almond acreage. With current data now available, almonds currently grow on 13% of California’s irrigated farmland but use only 9% of the state’s agricultural water.

(Last updated June 9, 2015)

1. California Department of Water Resources. California Water Plan, Update 2013. Volume 1, Chapter 3. October 2014.

2. Public Policy Institute of California. Just the Facts: Water Use In California. July 2014.

3. California Almond Sustainability Program, 2014.

4. California Department of Water Resources. California Water Plan, Update 2013. Volume 3, Chapter 2. October 2014.

5. California Department of Water Resources. California Water Plan, Update 2013. Volume 1, Chapter 3. October 2014.

6. University of California Agricultural Issues Center. The Economic Impacts of the California Almond Industry. December 2014.

7. Historical evapotranspiration rates from 1990-1994 UC Davis Drought Management - Historical Almond ET, see: Irrigation_Scheduling/Evapotranspiration_Scheduling_ET/Historical_ET/Almonds_960/. Evapotranspiration rates from 2010 – 2014 updated to new almond crop coefficients: Goldhamer, David. 2012. Almond in Crop Yield Response to Water. FAO Irrigation and Drainage Paper No. 66, P. Steduto, T.C. Hsiao, E. Fereres, and D. Raes, eds. Food and Agriculture Organization of the United Nations, Rome, Italy, pp. 246:296. Average almond pounds per acre 1990-1994 and 2010-2014: Almond Almanac.

8. California Almond Sustainability Program, 2014.