The US exports too much of its most valuable resource


In the past decade, however, these wells have started to run dry. Travel beyond the homesteads and family-run farms you’ll see why—thousands of acres of neatly ordered trees bearing pecans and pistachios, vast fields of alfalfa and corn, huge dairy herds, and rows of greenhouses growing tomatoes cover the once-barren desert. This enormous carpet of industrial agriculture, with food grown for export to places around the world, takes deep wells to sustain. For every 100 acres or so, a corporate farm owner will dig a well as deep as 2,000 feet and pull up water from the ancient aquifer at up to 2,000 gallons per second, often 24 hours a day. The drilling rigs often resemble those used for oil.

There are almost no regulations governing the extraction of groundwater in Arizona. As long as the farms pay a permitting fee, they can pump as much as they like. 

Added to the over-extraction of water from the aquifer, Arizona (along with the American Southwest in general) is now experiencing one of the worst droughts in hundreds of years, likely driven by global warming. As the region becomes hotter and drier, necessitating more extraction from the aquifer, less water trickles in from monsoons or snowmelt to replenish it.

What we don’t getabout the water cycle

In school we teach children about the water cycle, in which water moves from the oceans to the sky to the land to freshwater basins and eventually back to oceans. In this telling, the water we use never really disappears. 

But these tales gloss over something important: the water cycle can take decades or hundreds of years to complete a turn. Much of the fresh water we use every day comes from groundwater, which can take hundreds or thousands of years to accumulate. If we use water faster than it can be replenished, or pollute it and dump it into the seas faster than the natural water cycle can clean it, the resource will eventually run out.

If you instead think of water as a finite material being used up in much the same way as oil or gas, you quickly start to see its presence in every part of the economy. More than 70% of the water we use is put into food production, for example. But water is also used to make everything from T-shirts to cars to computer chips.

If they can’t find enough water within their own borders, the thinking goes, why not just import it (embedded in food) from somewhere else?

Like its cousin the carbon footprint, a water footprint can be a useful shortcut to understanding a product’s environmental impact—or your own. The water footprint of a cup of coffee is around 140 liters, for example. It takes about 15,000 liters to grow a kilogram of beef. A couple of slices of bread can rack up 100 liters. A kilogram of cotton (a pair of jeans and a shirt, say) can have a footprint of anything from 10,000 liters to more than 22,000 liters, depending on where it was grown.

This means that countries and companies, whenever they trade goods, are in effect moving massive amounts of water across borders. But because the water footprint of food or clothes or anything else is never acknowledged in this trade, the movement of water itself cannot be properly regulated.

Partly for this reason, richer countries such as Saudi Arabia and China have begun buying up land in other countries to compensate for their own lack of fresh water. If they can’t find enough water within their own borders, the thinking goes, why not just import it (embedded in food) from somewhere else? The problem is that the places they’ve been shopping are themselves water-stressed, including countries in sub-Saharan Africa and the Sulphur Springs Valley in southwest Arizona.

Why Arizona? Because the land is cheap and well connected to airports, and because water-use regulations are almost nonexistent.

The United States is, in fact, the largest exporter of water on earth, according to Robert Glennon, a law professor at the University of Arizona and one of the country’s leading experts on water policy. Glennon calculated that during a recent severe drought, farmers in the American West used more than a hundred billion gallons of water to grow alfalfa that was then shipped mostly to China.