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SALSA Science Helps Water-Scarce Southwest

Cottonwood forests and willow thickets that line the banks of the San Pedro River in southeastern Arizona make a welcoming green oasis in an otherwise dry landscape. Agricultural Research Service scientists and colleagues from the United States and abroad are scrutinizing the natural cycling of water through the San Pedro River Basin ecosystem. Their intent: to provide the science-based information needed to ensure that the 130-mile-long river will continue to supply ample water for people, plants and animals.

The collaboration, now in its sixth year, is known as SALSA, short for Semi-Arid Land-Surface-Atmosphere research program. Findings from SALSA should not only benefit cities, towns, farms, ranches, wildlife, industry and the military in the San Pedro Basin, but might also be applicable to other major river basins in semiarid ecosystems around the globe. That's according to hydraulic engineer David C. Goodrich of the ARS Southwest Watershed Research Center, Tucson, Ariz.

Much of the SALSA research focuses on developing new ways to predict how ecosystem changes caused by people or nature might affect the amount of water which moves into and out of a vast aquifer that feeds the Upper San Pedro River. The aquifer is relatively easy and inexpensive to pump. Not surprisingly, it is the sole source of water for rural and city residents in the basin and for the Fort Huachuca military base. Today, more water is being removed from the aquifer than is being replaced by rainfall and seepage, according to Goodrich.

SALSA investigations may lead to new and better ways to both balance the basin's water budget and meet the needs of those who use the water. Details are in the September 2002 issue of the ARS monthly magazine, Agricultural Research.

ARS is the U.S. Department of Agriculture's chief scientific research agency.