New Map Deepens Understanding of Cross-Border Aquifers

A new map of groundwater supplies could change the shape of water management and conservation policy in the U.S. Southwest and Mexico, reports Caroline Tracey in High Country News. “On Dec. 28, researchers released the first complete map of the groundwater basins that span the U.S.-Mexico boundary. It demarcates 72 shared aquifers — a striking contrast to the countries’ official count of 11.”

The map comes from research by Rosario Sánchez and Laura Rodríguez published in Transboundary Aquifers: Challenges and the Way Forward. “It shows five shared aquifers between Baja California and California, 26 between Sonora and Arizona, and 33 between Texas and the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas. Of these, 45% are considered to be in ‘good to moderate’ condition.”

The two countries have not previously collaborated on water regulation efforts, leading to incongruous uses and unsustainable exploitation of water resources, Tracey explains. The research standardizes the definition of an aquifer, which the authors hope will contribute to a better shared understanding of the intertwined water resources in the two countries. “Felicia Marcus of the Water Policy Group added that maps like the one Sánchez and Rodríguez produced ‘are helpful for transparency and allow for more engagement of the affected communities,’ particularly in resolution of disputes.”

More on the Southwest's water crisis:

• Southern California Water District Declares Drought Emergency
• Colorado River Compact Needs 21st Century Update
• California Governor Outlines Plan for a ‘Hotter, Drier Future’