Vast AZ, CA Farms Getting Hard Look As Southwest Long-Term Water Outlook Darkens

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There's no getting around the facts: Farmers use a lot of water in Arizona. With so little rain, they must irrigate every field of hay, every row of vegetables. In a year, agriculture consumes almost 5 million acre-feet of water, or 1.6 trillion gallons. The annual value of the crops alone is about $2 billion. Industry groups say that, including suppliers and related businesses, agriculture overall contributes more than $9 billion a year to the state's economy. At either estimate, though, agriculture accounts for just a fraction of Arizona's gross domestic product, which in 2007 was an estimated $245 billion.

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With a reliable water supply, farmers can manage their resources down to the drips in a tangle of irrigation hoses, a precision that helped Yuma grow into the nation's winter vegetable capital. Sellers said rain is an unwanted intruder during the growing season because it can't be managed.

One reason farmers can take so much water is that they staked their claim first, which is what matters in Western water law. Most of the irrigation districts in Yuma hold rights to the Colorado River that predate Hoover Dam, which means if the river starts to run dry, the farmers get their share before anyone else. They can lease water to other users but keep the long-term rights.

Together, the largest water districts in the Yuma area can divert more than 750,000 acre-feet of water from the Colorado each year. Metropolitan Las Vegas, with a population of more than 2 million, can draw just 300,000 acre-feet a year.

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http://www.azcentral.com/arizonarepublic/news/articles/2009/10/25/20091025water-users1025.html