For the first time, U.S. and Mexico take stock of the underground water they share

An unknown number of aquifers dot the border along the U.S. and Mexico, groundwater both sides use for agriculture, irrigation, and cities. Likewise, how much border communities rely on them and the ways they are managed by either country remain largely unclear. For a decade, researchers have attempted to study these transboundary aquifers, but limited funding from the U.S. government and a dearth of information have hampered their efforts. Now, though, the first leg of research is wrapping up on two major water systems: the San Pedro and Santa Cruz aquifers along the Arizona-Sonora border. Researchers can now present a more unified picture of groundwater systems and collaborate on their management – an increasingly pressing challenge in the age of climate change, shifting precipitation patterns and extended drought. In 2006, the two countries signed the Transboundary Aquifer Assessment Act, which allowed for assessment of major aquifers along the borders of Texas, Arizona and New Mexico: the Hueco Bolson and Mesilla Basin aquifers below El Paso and Ciudad Juárez and Arizona’s San Pedro and Santa Cruz aquifers. Congress authorized $50 million from 2007 to 2016 for the project, but ended up providing only a fraction of that. Despite the limited budget, the research team from the U.S. Geological Survey, Mexico’s National Water Commission, the University of Arizona and the University of Sonora in Mexico finished a report about the San Pedro Aquifer. The San Pedro study, a preliminary version of which was released in January, focused on land ownership, water and soil quality, and precipitation. It marked the first time the two countries collaborated aquifer research. The complete version will be published later this year, and a similar study on the Santa Cruz Aquifer is expected early next year...more