Rio Grande Water Sharing Needs Fixing

This brief is part of “Election 2024: Policy Playbook,” a series by Rice University and the Baker Institute that offers critical context, analysis, and recommendations to inform policymaking in the United States and Texas.

The Big Picture

• Mexico remains arrears in meeting its current cycle Rio Grande water delivery obligation to the U.S. as mandated by the U.S.-Mexico 1944 Water Treaty. 
• Drought and heightened water demand across the southeastern Rio Grande basin factor into Mexico’s decision to limit water releases to the U.S.
• The delays have created adverse economic conditions for Texas farmers and drawn sharp criticism of the treaty. 
• Mexico technically remains in treaty compliance so long as it can meet its obligations by the end of the treaty’s current five-year water delivery cycle in October 2025.
• With improved watershed management, more can be done to strengthen treaty compliance and alleviate stresses on water users in the Rio Grande basin.

Summarizing the Issue

Context

Since 1945, U.S.-Mexico water sharing on the southeastern stretch of the Rio Grande has been governed by the 1944 Water Treaty, which is administered by the International Boundary and Water Commission (IBWC). Article 4 of the treaty stipulates that Mexico deliver 350,000 acre-feet of water annually as a five-year delivery cycle average —adjustments to this obligation are possible under certain circumstances, such as extraordinary drought or storage dams reaching full capacity. But drought and over-allocation of water rights in both countries have made implementation of the agreement’s already complicated procedures even more complex.

In 2015 Mexico needed an extension of time to the next cycle and came perilously close to needing another rollover in 2020, when it met its five-year obligation with a last-minute transfer of reservoir water to the U.S., placing its own downstream water users in jeopardy. This understandably created political turmoil in states like Chihuahua and Tamaulipas. Since then, Mexico has delivered just under 23% of its current cycle obligation but technically remains in treaty compliance, depending on how much it delivers in the final year or if the remaining amount is carried over to the next cycle.

United States’ Position

Texas has accused Mexico of bad faith in its treaty compliance and claims economic damage amounting to several hundred millions of dollars to downstream irrigation districts. Water-intensive crops like sugarcane are virtually finished in the Rio Grande Valley and citrus production is also threatened. This is not only a water delivery volume issue. It also concerns the lack of reliability for annual deliveries, which impairs the ability of farmers to plan and finance crop production. Texas acknowledges drought is a factor but believes Mexico is hoarding available water in upstream dams on the Conchos River and other Mexican tributaries. It also argues that Mexico’s irrigation districts use water inefficiently, diminishing its capacity for treaty compliance, and points to U.S. compliance in meeting its water delivery obligations to Mexico on the Colorado River.

Mexico’s Position

Mexico not only concedes that it must comply with the treaty, but also notes the persistent drought, arguing it cannot deliver water it does not have and citing its obligation to meet the minimal needs of its own cities and farms. It points to its good faith efforts to work with the U.S. to upgrade its irrigation systems and dedicate the resulting saved water to treaty compliance. Mexico notes its willingness to engage in ongoing negotiations that include using U.S. analytical software to identify potential water efficiencies in its part of the basin. Importantly, it also accurately claims formal compliance with Article 4 requirements.

Expert Analysis

To be clear, Mexico — which bears the greater compliance burden — is currently treaty-compliant. But its erratic pattern of compliance over the past decade has cost Texas farmers, who depend on a reliable water supply. Protracted drought and Mexico’s response have exposed a flaw in the treaty’s Article 4 governing Mexico’s water delivery obligations, namely the need for reliable Rio Grande water deliveries over a five-year cycle. Predictability is essential, whether Mexico meets its treaty obligations or not. The treaty allows for periodic amendment and is not a barrier to change, provided both parties agree on needed modifications.

Progress Is Being Made

While the IBWC missed its December 2023 target for reaching a new agreement to improve the reliability and predictability of water deliveries for users in both countries, progress has been made. Under the 2020 interim agreement, Mexico improved its Rio Grande basin hydrological diagnostics by adopting U.S.-recommended analytical software. Conservation discussions by newly established binational policy and hydrology workgroups supporting treaty compliance are also ongoing.

Though not directly applicable to the current Rio Grande dispute, useful lessons may be drawn from recent accommodations addressing drought on the Colorado River, which is also shared by Mexico and the U.S. (Figure 1). There, negotiators acknowledged the common threat of climate change and sidestepped formal treaty provisions to reach a pragmatic, if temporary, solution to water shortages based on both countries accepting reductions pegged to declining water levels at Lake Mead. Mexico did not have to agree, but it did — both an act of courtesy and self-interest. Something similar may be possible on the Rio Grande if both countries embrace the wisdom of enhancing the predictability of water deliveries and agree on a new formula for reduced annual volume thresholds.

Figure 1 — Map Showing Rivers and the US-Mexico Border

Policy Actions

1. The U.S. and Mexico should focus their next Article 4 implementation agreement on ensuring reliable deliveries. This is important, although it may mean Texas Texas temporarily accepting reduced annual Mexican deliveries for a fixed interval.
2. The U.S. and Mexico should negotiate a basin-specific working definition of extraordinary drought. They should also define the operational indicators that trigger temporary reductions in Mexico’s stipulated annual delivery requirement.
3. Both parties should agree on conservation steps that apply to water users in both countries. They should also acknowledge climate change in all future water-sharing agreements.
4. Existing IBWC work groups should continue to focus on identifying and financing water usage efficiencies targeted at bolstering Mexico’s treaty compliance. These groups should pay specific attention to how more reliable deliveries can be made.
5. Incoming administrations in both Mexico and the U.S. should prioritize these issues. This can strengthen the 1944 Water Treaty in the process.

The Bottom Line

Conflicts between Mexico and the U.S. over the 80-year-old U.S.-Mexico Water Treaty could be reduced or eliminated if both sides agree on new stipulations that factor in drought, climate change, better definitions of key terms used in the treaty, and more specific requirements for adjusting the treaty’s provisions. Now is the time to come together and update the agreement before the current five-year term ends.

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