Click here to go to the Nature website to read the paper (Brian D. Richter, Dominique Bartak, Peter Caldwell, Kyle Frankel Davis, Peter Debaere, Arjen Y. Hoekstra, Tianshu Li, Landon Marston, Ryan McManamay, Mesfin M. Mekonnen, Benjamin L. Ruddell, Richard R. Rushforth & Tara J. Troy). Here’s the abstract:
Human consumption of freshwater is now approaching or surpassing the rate at which water sources are being naturally replenished in many regions, creating water shortage risks for people and ecosystems. Here we assess the impact of human water uses and their connection to water scarcity and ecological damage across the United States, identify primary causes of river dewatering and explore ways to ameliorate them. We find irrigation of cattle-feed crops to be the greatest consumer of river water in the western United States, implicating beef and dairy consumption as the leading driver of water shortages and fish imperilment in the region. We assess opportunities for alleviating water scarcity by reducing cattle-feed production, finding that temporary, rotational fallowing of irrigated feed crops can markedly reduce water shortage risks and improve ecological sustainability. Long-term water security and river ecosystem health will ultimately require Americans to consume less beef that depends on irrigated feed crops.
From The Guardian (Troy Farah):
Cattle-feed crops, which end up as beef and dairy products, account for 23% of water consumption in the US
A recent analysis published in Nature found cattle to be one of the major drivers of water shortages. Notably, it is because of water used to grow crops that are fed to cows such as alfalfa and hay. Across the US, cattle-feed crops, which end up as beef and dairy products, account for 23% of all water consumption, according to the report. In the Colorado River Basin, it is over half.
“There are many smaller streams that have been dried up completely,” said Brian Richter, the study’s lead author and the president of Sustainable Waters, a water conservation non-profit. “We’re only seeing the beginning of what’s going to become a major natural resource issue for everybody living in the western United States.”
Agriculture accounts for 92% of humanity’s freshwater footprint across the planet, and has long been identified as a major culprit in drought. But the new study suggests how extreme its impact can be.
“The fact that over half of that water is going to cattle-feed crops just floored us,” Richter said. “We had to double and triple check to make sure we got the numbers right.”
Lake Mead, in Arizona and Nevada, for example, hasn’t been full since 1983, and has fallen by almost two-thirds in the last 20 years alone. According to Richter’s analysis, almost 75% of that decline can be attributed to cattle-feed irrigation.
In the Colorado River Basin as a whole, which services about 40 million people in seven states and is overtaxed to the point that it rarely ever reaches the ocean anymore, that number is 55%.
It takes a lot of water to make a double-cheeseburger. One calculation puts it at 450 gallons per quarter-pounder. The study also found that most of these water-intensive beef and dairy products are being consumed in western cities. “Beef consumers living in the Los Angeles, Portland, Denver and San Francisco metropolitan areas bear the greatest responsibility for these hydrological and ecological impacts,” Richter and his colleagues reported.
Around 60 species of fish in the western US are experiencing increased risk of extinction due to draining water tables, according to the study. As streams dry up, toxic chemicals such as fertilizers and pesticides that run off from farms become concentrated, suffocating river-dwelling fauna. Invasive species can find a foothold in the changing environment…
The most cost-effective solution, proposed in Richter’s paper, is fallowing farmland, meaning letting it sit idle, without irrigation. “You can’t get more water savings off of an acre than by not watering it,” Richter said, and described it as “growing water” rather than a crop. He noted that the strategy should be temporary and rotational, and that ranchers should be compensated because they lose income growing nothing. Fallowing is at least twice as effective as other water-saving tactics, according to Richter’s analysis.
Agricultural strategies aside, people who eat beef and dairy will ultimately need to consume less or choose products that don’t depend on irrigated crops fed to cows, Richter said. Plant-based meat alternatives can play a role, as one analysis found that a meatless Beyond Burger generates 90% fewer greenhouse gas emissions and has practically no impact on water scarcity.