Lettuce Saves The Colorado River

Water levels are up this winter at Lake Mead, a gauge for the Colorado River’s ability to supply 30 million people with water, thanks partly to a surprising hero: lettuce.

Farmers’ switching to lettuce, which uses less water because it’s cultivated only part of the year, from alfalfa, a thirsty year-round crop, helped push the lake to 1,087.6 feet (331.5 meters) above sea level as of Jan. 31. That’s more than 1 foot higher than a year ago and above the benchmark of 1,075 feet, at which point regional water restrictions kick in.

The improvement, which brought a sigh of relief to a dry region, is mostly due to a record snowpack in the Sierra Nevada mountains that ended California’s drought by early 2017. But some credit goes to farmers, the biggest users of the region’s water, who in some places have been doing exactly what climate experts say they should be doing—switching crops for conservation reasons.

A look at 28 years of data from the Imperial Valley—a major crop-growing region spanning southeast California, bordering Mexico and Arizona and relying on Colorado River water—shows how farmers battling water scarcity have shifted acreage.

Acreage planted in alfalfa, a low-value forage crop, has declined 25 percent to 148,642 acres since 2001, according to December 2017 figures. Lettuce growth has increased 79 percent to 31,382 acres in the same period.

The shift is a combination of market and government incentives, said John Fleck, director of the University of New Mexico’s Water Resources Program in Albuquerque. Water-sharing agreements with local governments have reduced use at the same time that distribution networks for fruits and vegetables have improved, making it possible to ship fresh lettuce and other produce to more markets.

“Cutting water use doesn’t have to be the end of agriculture,” Fleck said. “Farmers with less water to use will maximize their drops, and find a way to maximize their profits.”

The changeover challenges the conventional wisdom that water demands don’t ease. It doesn’t, however, solve the long-term problems of the Colorado River. This year could be more difficult, with snowpack well below normal, according to the U.S. Bureau of Reclamation. The basin’s population may rise as much as 91 percent by 2060.

But at least one thing climate experts say must happen to manage the problem appears to be happening. That could put off the day of reckoning while the region seeks lasting solutions, Fleck said.

“You can go a long way with conservation,” he said. “The problem isn’t fixed, but we’re buying time.”