Monday, October 15, 2012

Water, Water, Not Everywhere

Few people in the world are more water-conscious than California farmers.
The state leads the nation in farm revenue and produces nearly half of the domestic supply of fruits, nuts and vegetables. It also boasts nine of the top 10 producing counties in the nation, according to the California Department of Food and Agriculture.
Yet California is one of the driest states in the U.S., getting an average of just 22 inches of precipitation annually compared with more than 40 inches for states like Missouri and New York. And, with nearly 40 million people, California is also the most populous state—meaning there's a lot of competition for that precious rain and snow.
How do the farmers make do with so little water? They use technology and the state's topography to stretch existing supplies as far as they can. "If you have limited water supplies, you have to be as careful and efficient as you can with it," says Larry Schwankl, an irrigation expert with the University of California Cooperative Extension.
The efficiencies start at the northern end of the Central Valley, the 400-mile corridor that's home to most of the state's farmland. There, farmers along the Sacramento River use a system called flow-through, which means that the water they take but don't use flows back into the river by a network of valves and drains.
As water flows to the driest southern reaches of the valley via the California Aqueduct, many farmers use drip irrigation, microsprinklers and extensively plumbed groundwater caverns—filled with runoff from the Sierra Nevada—to maximize their water usage.
Daniel Errotabere, for instance, says his 5,200-acre farm's conversion to drip irrigation over the past five years has helped yield water savings as high as 50%—helping to cushion the blow during the most recent drought. "You can't deliver water much more efficiently than what we are doing today," Mr. Errotabere said on a recent tour of the farm near Riverdale, Calif.
The accompanying images outline how irrigation and water conservation work in California's Central valley.

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