Mexico's Santa Clara marsh is home to the reddish egret (Egretta rufescens
Credit: Claudio Contreras
Binational Crusade to Save Wetlands
By Stephen Leahy
A powerful desalinization plant will reopen in 2007 near the Mexico-U.S. border. Scientists in both countries will be working to halt harm to the Ciénaga de Santa Clara, a large marsh in the northern Mexican state of Sonora.
TORONTO, (Tierramérica).- With 20,000 hectares of bright green in a sea of sand in the state of Sonora, the Ciénaga de Santa Clara is one of Mexico's richest coastal ecosystems. Faced with the immenent reopening of a desalinization plant just across the border in the United States, a binational team is working to protect the vast wetland.
Ongoing drought conditions in the southwest United States has prompted the George W. Bush government to finance the restart of the long unused Yuma Desalting Plant (YDP) in the border state of Arizona in 2007.
"Full operation of the desalting plant would mean the ciénaga will get less water and the water would be much saltier," said Karl Flessa, professor of geosciences at the University of Arizona in Tucson.
And "that would completely eliminate the wetland," according to Jaqueline García-Hernández, a scientist at a food and development research center in Sonora (Centro de Investigación en Alimentación y Desarrollo) in Guaymas, Mexico.
The Ciénaga de Santa Clara is home to some 225 species of birds, like the Yuma clapper rail (Rallus longirostris yumanensis) and southwest willow flycatcher (Empidonax traillii extimus), which are extraordinarily rare in the United States.
It is also an important stopover for birds that migrate along the Pacific Flyway route, and provides habitat and feeding grounds for an estimated 200,000 shorebirds, ducks and geese.
The Ciénaga de Santa Clara turns out to be an accidental wetland. One hundred years ago the Colorado River Delta spanned at least one million hectares at the top of the Gulf of California. Dams and water withdrawals, mainly in the United States, have resulted in the decline to a trickle of water from the mighty Colorado River reaching the Gulf today.
And that is only during the wet years, the last of which was 1997. The lush, green, marshy delta became little more than salt flats until the construction of a 56-kilometer drainage canal in 1977 to carry brackish agricultural wastewater from irrigated fields in Arizona.
This water is too salty to meet the United States' obligation to provide Colorado River water to Mexico, as stipulated by the 1944 Water Treaty between the two countries.
Despite being unsuitable for crops or the treaty, cattails and other wetland plants began to grow as 120 billion liters of wastewater nourished the parched soils each year. And so a small part of the delta was reborn.
"Although the water is no longer from the river, the Ciénaga has been relatively healthy for the past 30 years," says García-Hernández. In recognition of the area's importance, in June 1993 the federal government of Mexico included it in the 162,000-hectare Upper Gulf of California and Colorado River Delta Biosphere Reserve.
The delta has also been named a part of the Western Hemisphere Shorebird Reserve Network and now designated a UNESCO Biosphere Reserve. But there are some problems. Worrisome levels of selenium have been measured in some birds and fish from the Ciénaga.
The YBP plant -- which cost 250 million dollars (though some reports say 400 million dollars) could make things worse. The U.S. government began construction in the late 1970s to desalinate the water that now supports the Ciénaga de Santa Clara in order to clean it up to meet its treaty obligations with Mexico.
Instead, the low flow of extremely salty YDP wastewater went to the wetland instead. And in 1992, when the plant was finally completed, high streamflows on the Colorado River were sufficient to supply the low-salinity water the United States is required to provide Mexican farms and cities. High operating costs kept what was then the world's largest desalination plant shut down.
Now, the prolonged drought and ever-thirstier cities of the U.S. southwest has meant a revival of the decades old plan. Environmental groups have long been opposed, so it was with some surprise when they were asked to work with government agencies and the agricultural industry to find ways to meet the needs of water users in the United States and Mexico without harming the ciénaga.
Thus emerged the YDP/Ciénaga Workgroup, which called for a scientific monitoring program for the ciénaga that García-Hernández now leads.
In addition, the YDP will only operate at 10 percent capacity for three months during the northern hemisphere springtime while García-Hernández and her colleagues from Mexico and the United States measure the impacts.
"It marks the beginning of the end of one of the most bitter water wars on the Lower Colorado," said Jennifer Pitt of Environmental Defense, one of the non-governmental organizations participating in the Workgroup.
"It's a critical first step in a long-term, binational effort to systematically evaluate how variation in water quantity and quality affects the delta's ecosystems," said University of Arizona expert Flessa.
For her part, García Hernández stated: "I hope it will be an example of how other ecosystems in the delta can be restored... After all, species (birds, fish, animals) do not recognize borders."
* Stephen Leahy is a Tierramérica contributor