Hay grown for cattle consumes nearly half the water drawn from Colorado River, study finds

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In a new study, researchers found that alfalfa and other cattle-feed crops consume 46% of the water that is diverted from the river, accounting for nearly two-thirds of agricultural water use. The research also shows that agriculture is the dominant user of Colorado River water, accounting for 74% of the water that is diverted — about three times the combined usage of all the cities that depend on the river.

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The study, which involved a team of 12 researchers and was published in the journal Communications Earth & Environment, expands on previous research by including water use data for Mexico; the Gila River, a major tributary in Arizona; and supplies that are transported through canals and pipelines to areas outside the Colorado River Basin.

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The researchers analyzed all water diversions for agriculture, communities and industries from 2000 to 2019, and calculated annual averages. They also included estimates of how much water evaporates from the river’s reservoirs, and the uptake of water by vegetation in wetlands and riparian areas along the river. Together, those account for 30% of overall consumption.

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In the upper basin states — Colorado, Wyoming, Utah and New Mexico — cattle-feed crops consumed 90% of all water used by irrigated agriculture on average. In the lower basin states of California, Arizona and Nevada, hay accounted for 57% of agricultural water use, with more water going to crops such as wheat, cotton, oranges, lettuce and broccoli.

The researchers noted in the study that alfalfa is also attractive to growers for other reasons, including its hardiness and ability to survive with less water during droughts and then come back quickly once full irrigation resumes — functioning like a “shock absorber” for farmers dealing with unpredictable conditions.

Richter and other researchers have estimated that two-thirds of the alfalfa and other hay are used for beef cattle while the remaining third is used for dairy production.

Much of the hay is used to feed cows locally or in nearby states. But increasing amounts of hay have also been exported in recent years to countries such as China and Saudi Arabia. In one study, researchers at the University of Arizona examined crop data for seven Western states and estimated that 20% of the region’s total alfalfa production was exported in 2022.

Richter said he doesn’t think attempts at regulating crop types would work, but that creating financial incentives for growers to switch to less water-intensive crops can be effective. In a study last year, Richter and other scientists found that shifting from alfalfa to other types of hay, vegetable crops or wheat would save substantial amounts of water.

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As for the large acreages now growing alfalfa, Babbitt noted that the crop generates relatively low returns and is often the first one taken out of production when farmers agree to temporarily fallow fields. He said that makes the crop an obvious place to begin reducing water use.

“It is the most economical way, in the Colorado River Basin, of reducing consumption,” he said. “There are plenty of other areas in this country where there is more than adequate water to grow alfalfa and animal feed.”