Understanding and managing the stressed Mexico-USA transboundary Hueco bolson aquifer in the El Paso del Norte region as a complex system Zhuping Sheng · Jeff Devere Abstract As the latest drought has swept over the Resum´ e´ Alors que la derniere` secheresse´ a atteint toute la southwestern United States, most local and regional water partie Sud-Ouest des Etats-Unis, la plus part des distribu- providers have had to rely on ground water to meet their teurs d’eau, locaux et regionaux,´ doivent s’approvisionner water demands as surface water supplies have diminished. en eau souterraine des´ lors que les niveaux des eaux de sur- In areas near major population centers this situation has face ont diminues.´ Dans les zones proches des grands cen- continued to put strain and stress on already over-drafted tres densement´ peuples,´ cette situation a continuee´ a alter´ ee´ regional aquifers. Metropolitan centers throughout the des aquiferes` dej´ a` surexploites.´ Les centres metropolitains´ southwestern United States, as exemplified by Las Vegas, du Sud-Ouest des Etats-Unis (Las Vegas dans le Nevada, Nevada; Phoenix and Tucson, Arizona; and El Paso, Texas, Phoenix et Tucson dans l’Arizona, El Paso au Texas) sont have a history of over drafting their available ground connus historiquement pour surexploites´ leurs ressources water resources. How these stressed aquifers should be en eaux souterraines. Il devient urgent de definir´ un mode managed is an urgent issue. In El Paso, Texas long-term de gestion de ses aquiferes` surexploites.´ A El Paso dans groundwater mining in the transboundary Hueco bolson le Texas, le minage de l’aquifere` transfrontalier engen- aquifer has resulted in large water level drawdowns within dre un rabattement important dans le bassin, et plus the basin, particularly in several well fields. This situation particulierement` autour des zones de captage. Cette sit- has promoted the intrusion of brackish water into fresh uation a induit l’intrusion d’eaux saumatresˆ dans des zones water zones, and consequently reduced the volume of fresh d’eaux douces, et a par consequent´ reduit´ le volume d’eau water stored in the aquifer. Management of this aquifer is douce stockee´ et exploitable dans l’aquifere.` La gestion de made more complex as the water resources of the region cet aquifere` est par ailleurs complexifiee´ par la situation are shared across the United States/Mexico boundary and transfrontaliere,` d’autant que la zone frontaliere` connaˆıt the transboundary region continues to grow rapidly. This une croissance rapide. Cet article decrit´ la situation actuelle paper describes the current situation within the Hueco dans la vallee´ fermee´ du Hueco, due au sur-rabattement et bolson due to over drafting and continued reliance on the a` l’exploitation continue des eaux douces, et decrit´ com- fresh water in storage and describes how understanding ment la comprehension´ de l’aquifere,` vu comme un systeme` the dynamics of the aquifer as a complex system can offer complexe, peut offrir des perspectives de gestion amenant a` managerial perspectives that can be used to establish oper- des procedures´ operationnelles´ et a` des programmes a` long ational procedures and programs for bringing drawdowns terme permettant de ramener al’` equilibre´ la baisse des into equilibrium, increasing the longevity of the aquifer, niveaux d’eau. Ainsi la longevit´ e´ de l’aquifere` sera mieux gradually restoring water quality, and offering the hope of garantie, la qualite´ de l’eau sera graduellement restauree´ et utilization of the resource in a sustainable manner. l’utilisation de l’eau respectera le souci de developpement´ durable. Received: 10 September 2003 / Accepted: 22 February 2005 / Published online: 21 June 2005 Resumen A medida que la ultima´ sequ´ıa ha pasado lig- eramente sobre el suroeste de Estados Unidos la mayor´ıa C Springer-Verlag 2005 de abastecedores locales y regionales de agua han tenido Z. Sheng () que depender del agua subterranea´ para satisfacer sus de- Texas A&M University, Agriculture Research and Extension mandas de agua debido a que las fuentes de agua super- Center, 1380 A&M Circle, El Paso, TX 79927, USA ficial han disminuido. En areas´ cerca de centros poblados e-mail: [email protected] Tel.: (915)-859-9111 principales esta situacion´ ha continuado ejerciendo presion´ Fax: (915)-859-1078 en los ya sobre explotados acu´ıferos regionales. Los cen- tros metropolitanos en todo el suroeste de Estados Unidos, J. Devere por ejemplo Las Vegas, Nevada; Fenix´ y Tucson, Arizona; Director Community and Economic Development, Town of y El Paso, Texas tienen una historia de sobre explotar los Rangely, 209 E Main, Rangely, CO 81648, USA e-mail: [email protected] recursos de agua subterranea´ disponibles. Hydrogeology Journal (2005) 13: 813–825 DOI 10.1007/s10040-005-0451-8 814 La gestion´ de estos acu´ıferos estresados constituye un regional water resources planner, has invested heavily in problema urgente. En El Paso, Texas el minado de agua the management of the Hueco bolson aquifer. Over the past subterranea´ a largo plazo en el acu´ıfero transnacional several years, a series of projects have been undertaken Hueco bolson´ ha resultado en varios campos de pozos. to gain a more accurate knowledge of the current hydro- Esta situacion´ ha promovido la intrusion´ de agua salobre geological conditions within the aquifer. This recently hacia zonas con agua fresca y reducido consecuentemente obtained information has been used to formulate improved el volumen de agua fresca almacenado en el acu´ıfero. El management strategies to prolong the useful “life” of manejo de este acu´ıfero se hace mas´ complejo debido a que the groundwater resource for future generations and los recursos h´ıdricos de la region´ son compartidos a traves´ drought contingency. Recent successes include a deeper del l´ımite Estados Unidos/Mexico´ y la region´ transnacional understanding of current groundwater storage volumes continua´ creciendo rapidamente.´ Este art´ıculo describe la and flow conditions in the aquifer, and development of a situacion´ actual dentro del Hueco bolson´ debido a la sobre set of potential strategies for preventing further brackish explotacion´ y continua dependencia en el agua fresca alma- groundwater intrusion. These insights have been gained in cenada y describe como el entendimiento de la dinamica´ part from the results of groundwater modeling conducted del acu´ıfero como un sistema complejo puede ofrecer per- in a bi-national cooperation program with El Paso, Texas spectivas de gestion´ que pueden utilizarse para establecer and Juarez, Mexico through the International Boundary procedimientos operacionales y programas que conduzcan and Water Commission (IBWC) and the United States al equilibrio de los descensos, aumentando la longevidad Geological Survey (USGS) (Heywood and Yager 2003). It del acu´ıfero, gradualmente restaurando la calidad del agua, is expected that challenges in the management of the Hueco y ofreciendo la esperanza de utilizar el recurso de manera bolson can be resolved by integrating resource protection sostenible. with responsible utilization of the aquifer in conjunction with proactive management by all agencies within the Keywords Transboundary aquifer . Hueco bolson . region. Systems management of groundwater . Groundwater model . Brackish water intrusion Hydrogeology of the Hueco bolson aquifer Introduction The Hueco bolson aquifer is an unconfined and a semi- For nearly a century, El Paso and Ciudad Juarez in the El confined aquifer within a long, sediment-filled trough hav- Paso del Norte region, comprised of El Paso, Texas and ing a length of some 322 km (200 miles) and an average Las Cruces, New Mexico in the United States and Ciudad width of 40 km (25 miles) that lies between the Franklin, Juarez in Mexico (Fig. 1) have relied on the groundwater Organ, and San Andres Mountain ranges (west side) and the resources of the Hueco bolson as its major drinking water Quitman, Malone, Finlay, Hueco, and Sacramento Moun- source (Sayre and Livingston 1945; Ashworth and Hopkins tain ranges (east side). Hill (1900) first defined the Hueco 1995; White et al. 1997; Hibbs et al. 1997). Ciudad Juarez bolson as the whole basin including the Tularosa Basin presently fully depends on the Hueco bolson ground water as shown in Fig. 1. However, Richardson (1909) divided as its sole drinking water supply, as do several small the bolson into two parts: the Tularosa Basin to the north communities in New Mexico and U.S. Army Air Defense and the Hueco bolson to the south. The Hueco bolson and Artillery Center and Fort Bliss (Fort Bliss), El Paso, Texas. the Tularosa Basin are hydraulically connected to each El Paso continues to withdraw ground water from the other (Wilkins 1986) and have been combined into the Hueco bolson to provide 30 to 40% of its total water supply. Hueco-Tularosa aquifer (Hibbs et al. 1997). In this pa- This use of the aquifer amounts to mining the resource as per, Hill’s definition for the Hueco bolson will be used the Hueco bolson only receives a limited amount of natural to define the boundary of the aquifer, while the ground- and artificial recharge, all of which is much less than the water model only covers the southern part the Hueco current pumpage from the Hueco bolson (Ashworth and bolson. Hopkins 1995; Hibbs et al. 1997). As a result of such long- The Hueco bolson aquifer consists of unconsolidated term groundwater mining in the region, large water level to slightly consolidated deposits, composed of fine- to drawdown cones, as well as deterioration of water quality, medium-grained sand with interbedded lenses of clay, silt, have been observed and recorded over the last four decades gravel and caliche. Sediments in the bolson are fluvial, (Hibbs et al. 1997). Management of the aquifer has included evaporitic, alluvial fan, and aeolian in origin and have a reduction in pumpage and artificial aquifer recharge.