- The Colorado River and Rio Grande 鈥 two significant transboundary rivers at the US-Mexico border 鈥 are experiencing historic low water levels due to persistent droughts, increasing demand, and conflicting interests. In the face of climate change, competing water users in the borderlands, including plants and wildlife, are struggling to meet their own needs.
- The US and Mexico share water from the Colorado River and Rio Grande pursuant to binational agreements that have existed since the 19th century. The 1944 Water Treaty is a particularly important one, as it defined water distribution requirements and expanded the responsibilities of the International Boundary and Water Commission (IBWC), also known as the Comisi贸n Internacional de L铆mites y Aguas (CILA) in Mexico. The IBWC has been the primary arbiter in binational debates regarding water quantity and quality at the border.
- Structural and institutional asymmetries between the US and Mexico have made cross-border collaboration difficult.
Water security has been a growing concern at the US-Mexico border for decades. But in recent years, the situation has become critical, as persistent droughts, rising demand, and conflicting interests continue to strain two significant transboundary rivers 鈥 namely, the Colorado River and the Rio Grande. These rivers alone constitute two-thirds of the border, supplying water to an increasingly populated and industrialized region of the and . Those dependent on the dwindling resource are now facing the economic and environmental consequences of unchecked development.
The Colorado River

For the past 50 years, nearly of the Colorado River has been consumed as it flows south.
When the river reaches the Morelos Dam at the US-Mexico border, most of the little remaining water is sent to farmland in Baja California, Mexico. Instead of emptying into the Gulf of California, the river鈥檚 remnants now disappear south of the dam, leaving residents and wildlife in Baja California and Sonora with .
North of the border, signs of stress appear much earlier, however. In the Lower Basin, Lake Powell and Lake Mead reached in 2022, falling to just a third of their .
97% of the Colorado River Basin lies within the US. How the Upper and Lower Basins choose to address a warmer and drier climate, over-extraction, and the manipulation of water flow directly affects the border.
鈥淚n reality, local communities have very little power over water management along the border [...] While it is necessary to have national institutions regulating, managing, and allocating water, there is a clear need for more local community involvement.鈥
鈥 Dr. Francisco Valencia-Lara, professor at the School of Transborder Studies at Arizona State University
The Rio Grande

Extreme drought conditions and over-extraction have also caused tension for those dependent on the Rio Grande at the border, as competing water users struggle to meet their own needs. This situation, however, is arguably more contentious.
Since 1992, Mexico鈥檚 water deliveries to the US have been irregular. The current five-year cycle that ends in October 2025 is no different, as the US has only received a little over a of water thus far. Texas' agricultural sector has faced significant setbacks from deficient deliveries. Due to the lack of water, the state鈥檚 shut down last year. Its citrus industry is also under threat. As a result, Texan politicians have repeatedly threatened to on Mexico. The US State Department鈥檚 Bureau of Western Hemisphere Affairs also stated that it would Colorado River water deliveries to Tijuana. The recent dedicated to providing economic relief to Rio Grande Valley farmers has only mitigated some tension.
To make up for past shortfalls, Mexico has used its own storage from the and Reservoirs 鈥 two major water sources located and shared at the border that are experiencing record lows. Such last-minute decisions have provoked tension in downstream districts, where Mexican residents and farmers are already facing their own .
Governance and Water Allocations
The International Boundary and Water Commission (IBWC), also known as the Comisi贸n Internacional de L铆mites y Aguas (CILA) in Mexico, has been the primary arbiter in such binational debates. Its role is to apply the rights and obligations which the US and Mexico governments assume under and related agreements. The is a particularly important one, as it expanded the responsibilities of the IBWC and defined water distribution requirements.



It is important to note that the treaty was created when water from the Colorado River and Rio Grande was not as as it is now. Megadroughts and aridification were not accounted for.
Obstacles
The sharing of a finite resource often reveals the complexities of border community interdependence. This is especially the case at the US-Mexico border, where deep structural and institutional asymmetries between the two countries . While the institutional and legal framework of the US finds strength in its local governments, Mexico's framework is much more centralized. Despite the region鈥檚 shared water security issues, such polarization has contributed to the many difficulties of achieving cross-border cooperation.
鈥淸The 1944 Water Treaty] allows for absolutely anything if [the US and Mexico] agree. But that would imply a lot of changes on the Mexico side in terms of management of its water resources and governance schemes. It鈥檚 a big responsibility.鈥
鈥 Dr. Rosario Sanchez, senior research scientist at the Texas Water Resources Institute
Nevertheless, it is widely recognized that the border鈥檚 water crisis can only be addressed binationally. One path forward is to deepen our understanding of the border region鈥檚 unique environmental and socioeconomic conditions that are inextricably tied to the two rivers. Addressing this knowledge gap may provide border communities with the legitimacy needed to garner support from all levels.
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Mexico Institute
The Mexico Institute seeks to improve understanding, communication, and cooperation between Mexico and the United States by promoting original research, encouraging public discussion, and proposing policy options for enhancing the bilateral relationship. A binational Advisory Board, chaired by Luis T茅llez and Earl Anthony Wayne, oversees the work of the Mexico Institute. Read more
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