What's Your Water Footprint?

ON THE EDGE of Jim Diedrich's 1,500-acre almond and tomato farm is a rustic office where his son would normally be sitting in front of a flat screen, controlling a superefficient drip irrigation network. But he'll have some more time on his hands this summer. California is in the midst of its most severe drought in nearly 20 years. And to make things worse, two years ago a federal judge ruled that pumps in the Sacramento-San Joaquin Delta were killing off the threatened delta smelt. And so Diedrich's farm outside the Central Valley town of Firebaugh is receiving almost no irrigation water this year. Sitting in his office, commiserating with a neighboring farmer, he griped, "It's unbelievable the power of the goddamn wacko environmentalists."

Then his neighbor, Shawn Coburn, turned toward me and demanded if I knew how much water it took to grow one almond, a cantaloupe, or a pound of tomato paste. (I didn't. Turns out it's 1 gallon, 25 gallons, and 55 gallons, respectively.) "The people in the city, they don't know what their footprint on nature is," he scoffed. "They sit there in an ivory tower and don't realize what it takes to keep them alive."

Even in thirsty California, where the battle lines between the big rural irrigation districts and urban water utilities were drawn long ago, this was a new angle on an old argument. The farmers' complaint underscores a curious, often unexamined aspect of our relationship with water: Even as the greenest among us cut our showers short and let our toilets go yellow, we may be blissfully unaware that our household water use accounts for only 6 percent of the water that we consume. The other 94 percent comes from the products we buy, everything from almonds and tomatoes to blue jeans and microchips. (See "Big Gulp.") The average person in the developed world drinks a gallon of water each day but "eats" another 800 gallons. And as Americans, our water consumption per capita is twice the world's average. Each one of us uses enough water annually to fill an Olympic-size swimming pool—four times what someone in Yemen uses.

In an effort to get consumers, companies, and entire countries to recognize the true costs of their water use, a few environmental groups are promoting the concept of our "water footprint." The idea "very much brings the water problem to the people," explains its creator, Arjen Hoekstra, scientific director of the Netherlands-based Water Footprint Network. Just as calculating carbon footprints has encouraged—and shocked—many Americans into seriously considering their personal environmental impacts, Hoekstra hopes that water footprinting will reveal the gushing faucet behind every purchase we make. "And then it shows that maybe people can do something about it."

We've got a long way to go. In the past 50 years, the world's water use has tripled. More than a third of the western United States sits atop groundwater that is being consumed faster than it's replenished. Half of the world's wetlands are gone, killed off in part by irrigation and dams, which have destroyed habitats along 60 percent of the planet's largest river systems. Since 1970, the population of freshwater species has been halved; one-fifth of all freshwater fish vanished in the past century—an extinction rate nearly 50 times that of mammals. And consuming more water has concentrated pesticides and fertilizers in what's left over: It's unsafe to swim or fish in nearly 40 percent of US rivers and streams, and polluted water sickens nearly 3.5 million Americans a year.

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