Getting the salt out


For 14 years, a huge desalination plant has sat quietly, out of operation, on the banks of the Colorado River just north of the Arizona border. And just south of the border, the Cienega de Santa Clara, a manmade wetland of over 14,000 acres, has provided critical habitat for migrating birds.

The wetland and the desalination plant are intimately connected -- the wetland is nourished by the same water supply that was supposed to feed the plant -- and until recently, it seemed they would not be able to coexist.

In other arid Western regions, water projects have improved efficiency but left environmentalists scrambling to find new sources of water for drying marshes and lagoons (see our story The Efficiency Paradox). But when the Yuma plant shuddered to life this March for a test run, water managers, environmental groups and federal officials were confident the Cienega de Santa Clara would survive, thanks to some proactive planning.

The wetland owes its size to an international treaty requiring that 1.5 million acre-feet of Colorado River water arrive in Mexico each year. In the 1960s, Mexican farmers began complaining that salty water from the river was damaging their crops. The high salinity levels violated treaty requirements, and agricultural runoff from an irrigation district near Yuma turned out to be the culprit. In the 1970s, the salty runoff was diverted into the Cienega, which grew from its original 450 acres to today’s size.

The diversion was supposed to be temporary until a desalination plant could be built. But the plant, which was finished in 1992, never operated apart from a nine-month test run. The next year, flooding eliminated the need for plant operations. By the time water levels returned to normal, the Cienega was already a huge wetland, providing forage for birds on the Pacific Flyway and housing federally protected species like the Yuma clapper rail, southwestern willow flycatcher and a desert pupfish. The plant, with its high operating costs, remained closed (see our story Draining the budget to de-salt the Colorado).

Now, eight years into a drought, water managers are looking at ways to squeeze more water out of the river. The Central Arizona Project, which manages water for three Arizona counties, suggested reopening the desalination plant so that some of the salty water going into the Cienega could be cleaned and sent to Mexico; that would allow more water to be used upstream. However, redirecting the water feeding the Cienega could have dried up the huge wetland and resulted in environmental lawsuits. To avoid that scenario, Sid Wilson, general manager of the Central Arizona Project, brought together officials from the Bureau of Reclamation, environmental groups and water managers to hash out a solution.

The result is a three-month test period with the Yuma desalination plant operating at 10 percent capacity. The Central Arizona Project is paying for monitoring of the Cienega to ensure the wetlands are not harmed. “Our goal is to get the Yuma desalination plant up and running,” says Bob Barrett, spokesman for the Central Arizona Project, “but we’re not taking that tack at the expense of the environment.”

After the trial ends in mid-May, group members will decide what to do next, based on the efficiency and cost of plant operations. Jim Cherry, area manager for the Yuma office of the Bureau of Reclamation, says there are no plans to run the plant at full capacity yet. In determining the future of the plant, Barrett highlights the ongoing cooperation of the group, something that is, he says, “a revolution to the water world.”
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