Freshwater Challenges at the Texas-Mexico Border—Implications of Unmonitored Private Wells for Human Health




Olivares, Ruben

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Freshwater resources within transboundary aquifers are critical for the development of bordering nations. Effective management of these shared resources necessitates unified governance informed by robust scientific data. This study contributes a comprehensive geochemical database on groundwater quality in private wells along the US-Mexico border. We investigated three distinct aquifer types spanning four Texas counties. A multifaceted analytical approach measured major ion concentrations, trace elements, Rare Earth Elements (REEs), and the spectroscopic characteristics of Dissolved Organic Matter (DOM). This approach aimed to elucidate water-rock interactions, biogeochemical processes, potential anthropogenic influences, and the aquifers' vulnerability to future contamination. Groundwater samples (n=22) were collected from private wells across Maverick, Kinney, Dimmit, and Webb Counties. Major ion composition revealed three distinct aquifer types: A carbonate aquifer in Kinney County (Edwards-Trinity), an alluvial aquifer exhibiting reducing conditions in Dimmit and Webb Counties (Carrizo-Wilcox), and an evaporite-rich aquifer in Maverick County. Trace element concentrations generally adhered to Environmental Protection Agency (EPA) Maximum Contaminant Levels (MCLs) across all aquifers. However, the evaporite-rich aquifer displayed elevated Strontium (Sr) and Nitrate Nitrogen (NO3--N) exceeding MCLs. This suggests potential contributions from mineral dissolution and/or anthropogenic contamination, raising concerns for future water quality in Maverick County. This study underlines the importance of unified governance based on scientific data to ensure the sustainable management of these vital cross-border resources.



Colonias, Geochemistry, Trace Elements, Transboundary Aquifers