Researchers Map Transboundary Santa Cruz Aquifer System
A new unified scientific baseline provides critical data for the groundwater system shared by Arizona and Sonora.
Updated on Oct. 30, 2026 in Geography
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Researchers from the University of Arizona and the U.S. Geological Survey have established the first unified scientific baseline for the Transboundary Santa Cruz Aquifer System. The decade-long study mapping the groundwater shared by Arizona and Sonora was presented at a community forum.
Why it matters
Understanding this shared aquifer is essential for regional drought resilience, as groundwater pumping and water usage in Sonora directly affect municipal wells in Arizona communities. Stable water tables are vital for the region's agriculture, trade, and eco-tourism sectors.
The study utilized a decade of compiled regional water quality data to create a unified scientific baseline. Researchers identified that 80% of current river flow between Rio Rico and Tubac relies on effluent from the Nogales International Wastewater Treatment Plant.
The players
University of Arizona
This public research university in Tucson leads significant water resource studies through its specialized research centers.
U.S. Geological Survey
This federal science organization provides impartial information on the health of ecosystems and natural resources.
International Boundary and Water Commission
This binational agency applies the boundary and water treaties between the United States and Mexico.
University of Sonora
This public institution serves as the primary state university in the Mexican state of Sonora.
The details
The study, conducted under the International Boundary and Water Commission framework, involves partnerships with Mexico's National Water Commission and the University of Sonora. It highlights current environmental challenges, including E. coli presence in the Nogales Wash and elevated sulfate levels near historical mining sites in the Patagonia Mountains.
Timeline
2009: Infrastructure upgrades were completed at the Nogales International Wastewater Treatment Plant.
October 28, 2026: Researchers presented the study findings at a community forum.
The Big Picture
The research operates within the International Boundary and Water Commission framework, which governs binational water management. This study advances the commission's capacity by establishing the first unified scientific baseline for the Santa Cruz groundwater system.
The development of integrated 3D binational groundwater models will provide municipal planners with more accurate data for long-term drought resilience. This mapping helps protect local water supplies by identifying contamination risks like sulfate levels and E. coli in the watershed.
The takeaway
Reliable management of the Santa Cruz Aquifer requires continued binational cooperation and monitoring of water quality. Residents and stakeholders in border communities should track updates on groundwater levels to support local sustainability efforts.
Further reading
Learn more about how researchers are monitoring land use and resources in the Geography section.
Source note: This article includes information reported by Nogales International.
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