From the National Geographic (Ben Jervey):
Alfalfa grows fast, so every month or so, a harvester will cut the crop, which will then be packed into tight bales; trucked to Long Beach, California; and loaded on a tanker bound for China or Japan or the United Arab Emirates.
All across the lower Colorado River Basin—and especially in Yuma County, the Imperial Valley, and the Green River area in Utah—scenes like this are playing out with increasing regularity. What was once a reliable and local, if relatively low-value, crop has become a global commodity. But the fact that the Colorado River is fueling the export boom has some western water advocates worried…
When Robert Glennon, a water policy expert at the University of Arizona and author of the book Unquenchable: America’s Water Crisis and What to Do About It, first learned that the U.S. was exporting alfalfa crops that had been grown with the very limited western irrigation water, his reaction was “utter disbelief.”
Glennon crunched some numbers and figured that in 2012, roughly 50 billion gallons of western water—enough to supply the annual household needs of half a million families—were exported to China. Not literally bottled up and shipped, but embedded in alfalfa crops grown with irrigation water. And that’s just to China, which still trails Japan and the United Arab Emirates as a top destination for American alfalfa…
According to a UNESCO-IHE Institute for Water Education report published in 2011, the United States exports more than twice as much virtual water, about 82 trillion gallons, as any other country. That’s largely because American farms feed the whole world.
Of course, given all the foreign products that Americans buy, the United States is also the largest importer of virtual water, with roughly 62 trillion gallons coming into the country in the form of T-shirts and iPods and other products.
“We get a lot of criticism for how much water is going overseas in the form of alfalfa,” said Sharp, the Arizona farmer, “but alfalfa is exported far less than wheat or rice.”[…]
But what troubles Glennon, and others who obsess over the West’s water woes, is the growing trend of shipping hay overseas. “What’s new here is that hay is a forage crop, and the exports are coming from the West, where water is scarce.”