Hydrogeologic and Water Quality Issues Along the El Paso/Juarez Corridor: An International Case Study

Abstract

The twin cities of El Paso, Texas, and Juarez, in Chihuahua, Mexico, depend heavily upon well water from the Hueco Bolson aquifer for municipal and industrial water needs. Over-pumping of the Hueco Bolson aquifer has resulted in drawdown of the water table (as much as 150 ft [45.7 m]) and salinization by brackish water encroachment. Predevelopment ground-water flow pathlines ran from recharge areas along mountains to discharge areas at the Rio Grande. Pumping cones of depression beneath El Paso and Juarez have reoriented the hydraulic gradient, capturing the natural discharge of the aquifer. The deeper cone of depression is beneath Juarez. At one location in the aquifer, ground water now flows under the international border from the United States into Mexico. Chloride and other dissolved solids have increased over time in many municipal wells of El Paso and Juarez. Salinization of water wells is associated with extensive ground-water development and arid climate. A freshwater zone beneath El Paso and Juarez is underlain and in some places overlain by inferior-quality ground water. Mixing due to pumping, leakage from mud interbeds and artesian confining beds, cascading waters along well casings and screens, lateral saltwater encroachment, and potential upconing have degraded the freshwater zone. Other contaminants of concern in the aquifer include fecal coliform bacteria, and nitrate. Of particular concern are fecal coliform bacteria because many residents in Mexico use untreated well water.