As populations continue to swell on both sides of the Texas-Mexico border and competition for water becomes fiercer between agriculture and municipal users, the Rio Grande Regional Water Authority (RGRWA) is desperately on the hunt for new water sources.

With the help of U.S. Bureau of Reclamation, the RGRWA officials initiated a comprehensive Lower Rio Grande Basin Study in 2011 to determine if brackish groundwater desalination would be a potential alternative source of water to meet the region's long-term and rapidly growing water needs.

The study represented a cooperative project that included the 53 member entities of the RGRWA, the Bureau of Reclamation, Texas water and environmental agencies and the International Boundary and Water Commission (IBWC). The study also included an evaluation of the impacts of climate variability and change on water supply imbalances within the eight-county regions of South Texas.

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Now that a multiyear drought has confirmed prospects for a changing climate, the results of the study warrant a second look at its conclusions concerning the growing need for alternative water sources for the near future.

The region is largely dependent on water sources from the lower Rio Grande. But the vast majority of watershed that resupplies the river comes from Mexico and the run-off of water from the Sierra Madre mountain range. Water deliveries, managed by the bi-national IBWC, are relegated by terms of the International Water Treaty of 1944, more commonly called the U.S.-Mexico Water Treaty. Water from the Amistad and Falcon reservoirs is released through a network of canals managed by 27 individual irrigation districts.

 

While the supply issues facing the Lower Rio Grande Basin are complex, the history of water availability and the constantly increasing demand for more water has made it even more evident that a time is quickly approaching when the river's resources and its ability to resupply those resources from annual rain events will require more water than the river can provide, making alternative resources to meet the future water needs of the necessary and perhaps sooner than projected.   

The results of the two-year study have helped local water planners by identifying brackish water resources across the region that could fulfill those requirements. The study further confirmed that the construction of three desalination facilities may well represent the best option for meeting the needs of a soaring population and addressing a mounting water deficit projected to reach nearly 680,000 acre-feet of water per year (AF/yr) by 2060.