Our Water Matters

The Texas Water Resources Institute (TWRI) at Texas A&M University recently released its latest findings about a poorly understood, but increasingly important, international issue: transboundary aquifers. A TWRI team, led by Dr. Rosario Sanchez Flores, has formulated a “standardized and consistent” methodology to “identify and delineate geological boundaries using surficial geology as the main criterion” as well as “lithological characteristics, hydrogeological features, and topography” to complement the analysis and strengthen the findings. The challenge involved not only identifying the extent of the aquifers themselves, known also as hydrogeological units (HGUs), but also in characterizing their aquifer potential and water quality.

Established in 1952, the TWRI currently functions as “one of 54 institutes within the National Institutes for Water Resources,” according to its website, and provides “science-based, community-supported solutions for the state’s pressing water quantity and quality challenges.” As surface water becomes scarcer due to climate uncertainty, groundwater is rapidly becoming a strategic resource worldwide, especially along the international border between the U.S. and Mexico. Sanchez, a former diplomat with the Mexican Foreign Service who went on to earn a Ph.D. in Water Management and Hydrological Sciences from Texas A&M, started working on transboundary aquifers at the behest of one of her professors, Dr. Gabriel Eckstein. “He was interested in getting me involved with the topic considering my expertise, language and network on the Mexico side,” Sanchez recalled, “to work on water across borders, where I can use my strengths.” She has been working and publishing on transboundary water issues at an international and binational level since 2006.

Sanchez and her colleagues have identified some 72 HGUs along the U.S.-Mexico border, up from an official count of 11 just eight years ago. Of these 72 HGUs, at least 28 report good aquifer potential and water quality. Fourteen of these 28 HGUs are located between Texas and Mexico, and all of them report good to moderate aquifer potential and good to moderate water quality. These HGUs include the bolsons of Valle de Juarez, Mesilla, Red Light Draw, Green River Valley, Presidio and Redford in Far West Texas. Perhaps the most striking finding in the report for Texans is the assertion that the areas along the Texas-Mexico border “appear to be the most important for transboundary aquifer potential.”

The findings reveal “the increasing strategic value of groundwater resources that are shared in the region and that have the potential to become a driver for binational security.” However, “the topic has received limited attention at the binational level and even [fewer] funding priorities for continued research.” The study reflects two essential realities: 1) transboundary aquifer potential and quality are above average across half of the border region and 2) these shared systems are being used indiscriminately by both countries with no legal framework to protect them against depletion.

The study identifies several binational vulnerabilities, including “no agreement on the number of transboundary aquifers traversing the border … no recognized common methodology … for identifying or delineating the extension of a transboundary aquifer … [and no] formal legal and policy framework … to address transboundary groundwater management in the [U.S.-Mexico] border region.”

Any future approach to the issue will be particularly thorny on the Texas side of the border because of the rule of capture, the legal concept that a landowner is entitled to extract all the water from under his land, regardless of impacts on neighbors. According to Sanchez, “The Rule of Capture is totally contradictory to the current water threats we are facing. It works against sustainable use and a sustainable future … because it assumes there are no limits. It was conceived at a time when we thought water was an endless resource. Today we know it has its limits. So, we need to revise our traditional conceptions and priorities.”

As daunting as the challenges may appear, Sanchez and her colleagues also contend that “the transboundary aquifer topic offers an opportunity … to be creative, to propose, to imagine, to learn from each other, to respect differences, but above all, to finally understand that the groundwater sharing notion is not limited to water.” 

The complete study findings can be found in “Transboundary Aquifers: Challenges and the Way Forward,” and more information is available through Texas A&M’s Transboundary Water Portal.

Trey Gerfers is a San Antonio native and serves as general manager of the Presidio County Underground Water Conservation District. He is also chairman of the Presidio County Water Infrastructure Steering Committee and board president of the Marfa Parks and Recreation Board. Trey has lived in Marfa since 2013. He can be reached at [email protected]