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But in the last ten years, these wells have started to dry up. Travel beyond the farms and family-run farms and you’ll understand why—thousands of acres of neat trees bearing walnuts and pistachios, vast fields of clover and corn, huge herds of dairy, and rows of greenhouses growing tomatoes, lining the once barren desert. This huge carpet of industrial agriculture, with food grown for export around the world, needs deep wells to sustain it. For every 100 acres, a company rancher digs a well to a depth of 2,000 feet and draws water from the ancient aquifer at up to 2,000 gallons per second, usually 24 hours a day. Drilling rigs are generally similar to those used for oil.
There are virtually no regulations governing the extraction of groundwater in Arizona. Farms can pump as much as they want as long as they pay permit fees.
In addition to excessive water withdrawal from the aquifer, Arizona (along with the Southwest America in general) is experiencing one of the worst droughts in hundreds of years, possibly due to global warming. As the region gets hotter and drier, less water drips from monsoons or melting snow to replenish it, as more water is drawn from the aquifer.
What we don’t understand about the water cycle
In school we teach children about the water cycle, in which water moves from the oceans to the sky, land, freshwater basins, and eventually back to the oceans. The water we use in this narrative never really disappears.
But these stories highlight something important: It can take decades or hundreds of years for the water cycle to complete a turn. Most 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 filled, or pollute it and dump it into the seas faster than the natural water cycle can clean it up, the resource will eventually run out.
If you instead think of water as a finite material used in the same way as oil or gas, you quickly begin to see its presence in every aspect of the economy. For example, more than 70% of the water we use is used for food production. 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 borders, why don’t they import it from elsewhere (included in food) and consider it?
Like its cousin the carbon footprint, a water footprint can be a useful shortcut to understanding the environmental impact of a product or your own. For example, the water footprint of a cup of coffee is around 140 liters. About 15,000 liters are needed to raise one kilogram of beef. A few slices of bread can reach 100 liters. A kilogram of cotton (for example, a pair of jeans and a shirt) can have a footprint of anywhere from 10,000 liters to 22,000 liters, depending on where it is grown.
This means that when countries and companies trade in goods, they are actually moving large volumes of water across borders. But since the water footprint of food, clothing or anything else is never accepted in this trade, the movement of water cannot be properly regulated.
Partly for this reason, wealthier countries such as Saudi Arabia and China began to buy land from other countries to make up for their own freshwater shortages. If they can’t find enough water within their borders, why don’t they import it from elsewhere (included in food) and consider it? The problem is that the places where they shop, including countries in sub-Saharan Africa and the Sulfur Springs Valley in southwestern Arizona, are experiencing water stress themselves.
Why Arizona? Because the land is cheap and well connected to airports, and water use regulations are virtually nonexistent.
The United States is actually the largest exporter of water in the world, according to Robert Glennon, a professor of law at the University of Arizona and one of the nation’s leading experts on water policy. Glennon calculated that during a recent severe drought, farmers in the western United States used more than a hundred billion gallons of water to grow alfalfa, which was then shipped mostly to China.
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