WATER POLITICS

As climatic changes continue to grip the American Southwest and precipitation declines, communities across the U.S.-Mexico border are not looking to the skies. Rather, they are turning their eyes to the ground below them, specifically to the numerous aquifers that cross the frontier. Unfortunately, a dearth of information, lack of monitoring, and near absence of cross-border cooperation make it unlikely that the region’s last vestige of native water will quench their growing thirst.

Hidden all across the frontier, from Baja to the Gulf, more than seventy subsurface formations holding precious groundwater crisscross the Mexico-US border. For many border communities—like Ciudad Jua?rez in Chihuahua, Ciudad Acun?a in Coahuila, Del Rio in Texas, Nogales in Sonora and Arizona, and a dozen others—the water in these transboundary aquifers is the only reason they continue to survive the parched frontier.

Despite this heavy reliance, information about these resources is desperately lacking. Few aquifers have been explored or monitored, and scant information is available on the origins of the water, as well as their recharge rates, the extent of withdrawals, chemistry, flow rates, direction, dependent ecosystems, and much more. What is known is that many of the aquifers along the frontier are being overexploited as populations and industries expand, with little regard for sustainability or cross-border consequences. Moreover, many are polluted due to poorly regulated–or unregulated–agricultural and municipal runoff, industrial waste, and mining activities.

More troubling, though, is the reality that the two nations have yet to ink an agreement addressing how these underground resources might be managed, shared, exploited, or protected. In fact, groundwater has long been neglected in Mexico-US political relations. Transboundary aquifers are excluded from the existing treaty regime, rarely appear on the binational agenda, and have only sporadically received the focus of federally funded research. Without cooperation, these resources are doomed to dwindle, jeopardizing the viability of the region’s communities, economic growth, and environment.

As temperatures continue to rise and droughts become more widespread, there is an urgent need for action on the region’s transboundary aquifers. Information on the border region’s groundwater is desperately needed, especially for those aquifers underlying cities and communities that depend on the subsurface resources for their survival. That information must also be shared and exchanged between the two neighbors, especially among stakeholders, local and regional leaders, and academics. In addition, where rivers do traverse the frontier—such as the Rio Grande, Colorado River, Tijuana River, San Pedro River, and Mimbres River—information on the hydrological relationship that those rivers have with surrounding aquifers must be explored to better understand how they influence each other.

The two countries and the border states should also come to terms with administering these shared resources, especially their allocation, and protection. Ideally, because every subsurface formation tends to function differently, Mexico and the U.S. should develop aquifer-specific rules, policies, and procedures for the most critical aquifers on the border. If that is not possible, at the very least, they should develop principles and priorities to guide them in managing these critical freshwater resources under drought conditions.

Lastly, the two nations should facilitate public participation in the decision-making process, especially from local and regional stakeholders. Groundwater use is a local activity. Local institutions and communities may not always have the resources or technical knowledge to address broad and scientifically complex transboundary challenges, yet they are typically better informed about local cross-border needs and challenges. They are also likely to be more responsive and adaptable to evolving environmental and economic circumstances.

Relying on the Rio Grande, Colorado River, and the other rivers that cross the Mexico-US frontier is no longer an option. Overallocation and climate change-driven droughts have made it a foregone conclusion. If the border region is to have a future, it lies underground in its aquifers.