A recent study looking at the link between human water use and water scarcity in the United States has found that irrigation of crops to feed cattle is a leading driver of water shortages in the western United States, informs The Guardian. The analysis led by Brian Richter, president of the non-profit Sustainable Waters and published in Nature Sustainability, found that cattle-feed crops such as alfalfa and hay account for 23% of water consumption nationwide, which increases to 55% in the Colorado River basin.
In the first 15 years of this century, annual flows in the Colorado River decreased by 19% compared with the average for the 20th century. Global warming is taking its toll in the basin, increasing the risk of water shortages. In addition, consumptive water uses have gradually increased in the past century. Water flows in the Colorado River Basin are overallocated to different uses, leading to the drying of the Colorado delta in Mexico and the depletion of Lake Mead, the largest reservoir in the United States. Some 40 million people in seven states depend on water resources from the Colorado basin.
Although worldwide agriculture in general has long been known as the biggest user of water, the new study shows how severe the impact of a specific type of crop ─ irrigated cattle feed ─ is in the Colorado River basin. The water footprint of a hamburger is bigger than we might imagine: an estimated 450 gallons for a quarter-pounder. That beef is consumed in western cities: Los Angeles, Portland, Denver and San Francisco, according to Richter and colleagues.
What can be done to improve the situation in the basin? Efforts to restore rivers and improve irrigation systems have been ongoing for years by ranchers like Paul Bruchez in partnership with conservation groups. Moreover, Richter’s paper proposes rotational fallowing of farmland ─ letting it sit idle ─ as a means for reducing consumptive water use. It would be a temporary measure, where ranchers are compensated for their lost income. The cost could be shared among the 40 million consumers of Colorado River water.
Our individual food choices, the amount of beef and dairy that depend on irrigated crops to feed cows, would also have an impact on water use. However, Dr Shelie Miller, director of Program in the Environment at the University of Michigan, warns that while we can reduce our individual water and energy footprint, “it is difficult to guarantee that there would be a subsequent decrease in water stress in the western US with decreased beef consumption”, because of the multiple competing water demands in the western region of the United States.