Reliability Trumps Quantity in the Rio Grande Water Dispute

The Issue

In November 2024, the United States and Mexico, acting through the offices of the International Boundary and Water Commission (IBWC), reached an agreement to address Mexico’s immense Rio Grande water debt. While instantly dissatisfactory in both countries, offering little immediate water relief to Texas and threatening Tamaulipas’ secure claim to the Rio San Juan, the agreement, IBWC Minute 331, is in fact progress. Yet, South Texas farmers still require more relief. Additionally, the focus of negotiations should be on water reliability, rather than quantity, to support all users on both sides of the border.

Background

The issue of Mexico’s water debt has been gestating for over two decades. Mexico first missed its deadline under a five-year treaty contract to send 1.75 million acre-feet of water to Texas in 1997, requiring U.S. forbearance and a willingness to carry the Mexican debt to the next five-year cycle, a procedure allowed by the 1944 U.S.-Mexico Water Treaty. In 2002, Mexico missed its target again, resulting in accusations, lawsuits, interim agreements, and investments in Mexican water conservation upstream. While some of these measures worked for a while, Mexico’s payments lapsed yet again in 2015. Mexico repaid that debt in 2016 but then nearly missed its 2020 target, transferring water just three days before its deadline.

New Agreement’s Pros and Cons

Following these events, the two countries pledged to find a solution by December 2023. This new agreement, nearly a year overdue, finally materialized on Nov. 7, 2024.

Minute 331 focuses on improving reliability flows by allowing Mexico to do the following:

• Use two of its downstream rivers, the Rio San Juan and Rio Alamo, to fulfill its treaty water obligations.
• Bank waters from its other named Rio Grande tributaries in the river’s two large storage dams.

These are important Mexican concessions that not only better satisfy its delivery obligations to the U.S. but also could improve the reliability of Mexican water deliveries.

However, this by no means provides short-term relief to Texas’ Rio Grande Valley farmers. Tamaulipas’ irrigators, who are served by the two downstream rivers, are also incensed, accusing the Mexican president of compromising the country’s sovereignty.

Cost to Texas Farmers

The treaty’s Rio Grande rules, originally designed to accommodate the vagaries of Mother Nature, are quite flexible, promising Texas 350,000 acre-feet of water annually, but only as an average over a five-year delivery cycle. In times of drought, this allows Mexico to hedge its annual water deliveries, undercutting Texas’ downstream irrigators’ ability to predict and reliably plan their water budgets.

The cost to Texas irrigators is considerable. Texas claimed hundreds of millions of dollars in farm losses over the past decade. Sugar cane, a water-intensive crop, is practically finished in the Rio Grande Valley. Citrus production and melons could suffer a similar fate.

Water Insecurity in the Rio Grande

Texas has accused Mexico of hoarding its water resources and demanding strict treaty compliance. Mexico, meanwhile, points to region-wide drought and serious reservoir stock depletion as diminishing its capacity to meet delivery targets.

For the moment, Mexico remains in treaty compliance until October 2025, but that fact obscures the underlying dilemma. Water insecurity plagues much of the Rio Grande basin, a function of chronic drought, inefficient water uses, and the over-allocation of water rights on both sides of the boundary.

With less than a year left in the current delivery cycle, another late cycle water transfer would not solve the underlying issues for a more reliable annual Rio Grande water supply. The new agreement is progress, and provisions for new work groups to study compliance options, support conservation projects in both countries, and conserve riparian ecology also help. However, it is not enough.

Policy Recommendations

To mitigate these issues, both countries should make further concessions that depart modestly from the 1944 treaty. This can be done without changing the treaty’s terms.

1. Both countries should acknowledge the fact of persistent region-wide drought caused by a changing climate and operationally define shortage conditions in Mexico’s part of the Rio Grande basin — mirroring what’s been done on the Colorado River, where basin-wide and binational conservation measures are held to storage levels at Lake Mead.
    
2. Both countries should agree to accept shortage-triggered cuts in water usage coupled to additional conservation measures as feasible, with Mexico shouldering the greater burden of sacrifice to honor its treaty obligation. Such measures would ensure reliable flows for downstream stakeholders, benefiting irrigators and municipal water utilities.
    
3. Through the newly established Rio Grande Projects Work Group, the U.S. should continue to help finance conservation improvements in Mexico’s hydraulic system that reduce water losses and buffer adverse impacts on Mexico’s irrigators and water utilities. Some subsidies and transfer payments may be needed to cover losses on both sides of the border. These arrangements should be codified in agreements of temporary duration which could be made concurrent with existing five-year cycles. And, if the main stem Rio Grande dams were to fill, the treaty’s Article 4 that would cancel Mexico’s debts and set a new five-year cycle should activate. In effect, this would terminate the interim arrangement pending renewal should shortage conditions return.

Key Takeaway

The present challenges of U.S.-Mexico water-sharing on the treaty rivers are historic and unfolding amid climate dynamics the 1944 treaty’s negotiators did not foresee. Their treaty has served both countries well, but now, new U.S. and Mexican administrations should take advantage of the treaty’s elasticity and adaptability. If the reliability of water flows rather than quantity takes center stage in treaty negotiations and new provisions, a path forward is possible.

This publication was produced on behalf of Rice University’s Baker Institute for Public Policy. Wherever feasible, the material was reviewed by external experts prior to its release. Any errors are the responsibility of the author(s) alone.

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