Delta beast rears its head

The U.S. Department of Interior may be ready to resurrect the Yuma Desalting Plant

  • Yuma Desalting Plant

  • Cienega de Santa Clara map

    Diane Sylvain

The Southwest’s voracious demand for water has already decimated the Colorado River Delta, turning millions of acres of jungle-like wilderness in northern Mexico into sterile salt flats. During dry years, the river — once mighty enough to carve the Grand Canyon — peters out before it reaches the Gulf of California.

And now, the little habitat still remaining in the delta may disappear, as the U.S. tries to squeeze more water out of a river system gripped by record drought (HCN, 7/3/00: A river resurrected). To send more water to Sunbelt cities and Southwestern farms, the U.S. is planning to restart its Yuma Desalting Plant.

Each year, the U.S. is required to send Mexico about 10 percent of the Colorado’s average flow — about 500 billion gallons a year — which is mostly used by farms south of the border. But the water needs to have no more than a certain percentage of salt, and the runoff from U.S. farms into the Colorado is extremely salty. So in 1975, the Bureau of Reclamation began to build the Yuma Desalting Plant.

Wet years in the 1990s meant that the U.S. didn’t need to use the desalter, however, and the $222 million plant — which critics derided as a classic federal boondoggle — has been stuck in mothballs since its completion in 1992 (HCN, 2/21/94: Draining the budget to desalt the Colorado).

Now, the U.S. Department of the Interior is looking to bring the plant back online. And once it’s running, the plant will pour its poisonous saline dregs into the Sonoran Desert’s largest wetland, the 12,000-acre Cienega de Santa Clara.

“It’s caught some of us a little off-guard, because all along we’ve assumed it was a white elephant that would never come online,” says Steve Cornelius, director of the Sonoran Desert Ecoregion Program of the Sonoran Institute in Tucson.

“Milk and honey wilderness”

The plant would use reverse osmosis to treat brackish water flowing off cropland in southwestern Arizona’s Wellton-Mohawk farming district, returning the “desalted” water to the Colorado for use downstream in Mexico. The “reject stream” of toxic brine would be sent through a parallel canal to Mexico, and then dumped in the cienega.

The cienega has been receiving the runoff from the Wellton-Mohawk fields. Nowhere near as salty as the concentrated brine that the desalting plant would pump out, the runoff has allowed the continued blossoming of the cienega in a dusty floodplain that is otherwise cracked like sunbaked skin and coated with a frosting of salt.

The cienega still offers a glimpse of the “milk and honey wilderness” that Aldo Leopold toured by canoe with his brother in 1922, roasting quail over mesquite fires and climbing cottonwoods to scout the river’s path. “The river was nowhere and everywhere, for he could not decide which of a hundred green lagoons offered the most pleasant and least speedy path to the Gulf,” Leopold wrote. “So he traveled them all, and so did we.” In the days before Hoover Dam, which was completed in 1936, Leopold recorded clouds of waterfowl, bobcats fishing for mullet, and families of raccoons munching on water beetles.

Declared a biosphere reserve by Mexico in 1993, the cienega provides habitat for 280 species of birds, including the largest-known population of endangered Yuma clapper rails. The endangered desert pupfish lives in its olive waters. Local residents have developed a fledgling ecotourism industry around the cienega, renting canoes so visitors can paddle among the hissing reeds.

Changing course

Because the U.S. doesn’t receive credit for the 35 billion gallons of brackish runoff it sends to the cienega every year, it has to draw an equal amount of freshwater from Lake Mead and deliver it to Mexico. Now, with reservoirs like Mead “dropping at a record pace,” Interior Secretary Gale Norton says the U.S. must change course. That may mean restarting the desalting plant.

If that happens, the cienega will get only a third as much water — and that water will be three times as salty, according to the Interior Department’s own proposal, which was approved by the House of Representatives in July. In a letter to Congress, Norton acknowledged that restarting the Yuma plant “would be met with substantial controversy” because it “may degrade” the cienega’s ecology.

That’s an understatement, according to Ed Glenn, a scientist with the University of Arizona’s Environmental Research Lab who has studied the area since 1991. He says he’s already worked on several federally sponsored studies that clearly show the cienega would be ravaged by the desalter. “That water would not meet any kind of standards for discharge in the U.S.,” Glenn says. The cienega’s vegetation would disappear: “It would become a repository for selenium-laden, poisonous water.”

Secretary Norton has suggested moving forward on two fronts: preparing to fire up the Yuma plant while looking for new sources of water for the cienega, such as farmers’ water rights. But Assistant Interior Secretary Bennett Raley, considered the Bush administration’s point man on Western water issues, says no decision has been made on the Yuma plant. Mexico has yet to be officially notified about the plans, and will certainly demand an environmental impact statement and mitigation, says José Campoy, manager of the national preserve that includes the cienega.

Interior acknowledges that the plant might require expensive upgrades, and cost $26 million to $34 million to run each year. But those numbers are way off, says Lisa Force, program director of Living Rivers in Scottsdale, because the agency has underestimated the cost of operating the plant and overestimated the price of alternatives.

“At a time when federal deficits are skyrocketing, it’s unbelievable that Congress would consider throwing away taxpayers’ dollars to retool this plant,” she says.

The author is the environment writer at the Arizona Daily Star in Tucson.

Living Rivers in Moab, Utah, 435-259-1063, in Scottsdale, Ariz., 480-990-7839,

Sonoran Institute in Tucson, Ariz., 520-290-0828,

U.S. Bureau of Reclamation Yuma Desalting Plant, 928-343-8100 or 800-433-8464,

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