Geochemical Analysis of Recharge and Groundwater Salinization in the Northern Hueco Bolson Aquifer, El Paso, Texas

Abstract

Identification of recharge waters, groundwater flowpaths, and solute sources is needed to best manage the increasing salinity of the Hueco Bolson aquifer, the primary water resource for El Paso, Texas and Juárez, Mexico. To address these issues, we have analyzed for a suite of geochemical tracers on water samples collected from 33 discrete vertical zone test holes. On the basis of δD and δ¹⁸O data, two regional recharge sources were recognized, one originating from western mountain-fronts and one from through-flow of the adjacent Tularosa aquifer. Chloride concentrations were strongly correlated with lithologic formations and both Cl/Br and ³⁶Cl ratios suggested halite dissolution within the Ft. Hancock formation as the primary chloride source. In contrast, sulfur isotopes indicated that most sulfate originates from Tularosa Permian gypsum sources. These sources suggested that chloride salinization of wells is the result of direct upconing of waters from the Ft. Hancock formation.