In DepthRiver Restoration

U.S.-Mexico water pact aims for a greener Colorado delta

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Science  18 Aug 2017:
Vol. 357, Issue 6352, pp. 635
DOI: 10.1126/science.357.6352.635

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In March 2014, 130 million cubic meters of Colorado River water began pouring through the Morelos Dam near Yuma, Arizona, and into the river's long-parched delta in northwestern Mexico. The 8-week flood was part of a massive ecological experiment, aimed at figuring out ways to restore some of the lush marshes and riverbank vegetation that once made the delta a haven for wildlife. Now, that experiment—which produced mixed results—is helping shape a new water sharing agreement between the United States and Mexico. As soon as next month, officials are expected to sign the deal, which will dedicate a small supply of Colorado River water to delta restoration work from 2018 through 2026. Researchers say it could allow managers to steer crucial trickles of water to specific restoration projects that are having a marked impact. Even a little water can bring real benefits to the delta, says conservation biologist Karl Flessa of the University of Arizona in Tuscon. But it takes a lot of hands-on management. "Restoration requires much more than just putting water in the river channel and letting nature take its course," he says. "What's really going on is we're farming nature."