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handle is hein.crs/govetse0001 and id is 1 raw text is: Congre Wonal Research Berib infon ing I 1e I live (V )ate o I~ 14 Updated March 6, 2026 1944 U.S.-Mexico Water Treaty: Issues in the 119th Congress A water treaty from 1944-the Treaty on Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande (1944 Water Treaty)-between the United States and Mexico and other binational agreements guide how the two governments share flows of the Rio Grande and Colorado Rivers. The 1944 Water Treaty states that the countries agree to give preferential attention to solving all border sanitation problems (e.g., flows of raw sewage and industrial wastewater in the Tijuana River Valley [TRV]). The binational International Boundary and Water Commission (IBWC), which was established in 1944 pursuant to the treaty and administers agreements on river flows and sanitation issues, is the principal venue for addressing related disputes between the United States and Mexico. The IBWC develops rules and proposed decisions, called minutes, on treaty execution and interpretation. Congressional considerations during the 119th Congress may include executive branch actions on U.S.-Mexico water matters and their role and effect on U.S.-Mexico cooperation, congressional responses to these actions and actions by Mexico, and forthcoming recommendations on addressing water management and sanitation issues. Rio Grande The 1944 Water Treaty addresses the Rio Grande basin below Fort Quitman, TX. Among other things, it establishes that the United States has a right to flows from tributaries that feed the Rio Grande in the United States and one-third of specified Mexican tributaries flows, which must average at least 0.35 million acre-feet (MAF) per year, measured in five-year cycles (1.75 MAF total). It also provides for the construction of international storage dams on the Rio Grande. Among other infrastructure, IBWC operates two international Rio Grande dams and their reservoirs. On multiple occasions since 1994, Mexico has not met its Rio Grande delivery obligations for a cycle. As of late October 2025, at the end of the previous five-year cycle, Mexico had delivered 0.88 MAF, according to IBWC. The Consolidated Appropriations Act, 2026 (P.L. 119-75, Division F, Section 7045(h)(1)), conditioned some funds provided therein on the Secretary of State certifying Mexico's delivery of Rio Grande water owed to the United States, as prescribed in the Treaty. In February 2026, the U.S. Department of State announced that Mexico had committed to make annual deliveries of at least 0.35 MAF and to develop a plan to address the 2020-2025 cycle's shortfall. Mexico not meeting five-year cycle delivery requirements, and the consequences for the Texas economy, has led some U.S. stakeholders to support mechanisms to achieve more reliable and predictable water deliveries. Although Mexico's internal water management influences deliveries, stakeholders have identified various other factors that may contribute to delivery shortfalls under recent cycles, including drought conditions in portions of Mexico's Rio Grande Basin and weather and climate patterns. In 2022, the U.S. section of the IBWC commissioned a study on the challenges to improving reliability and predictability of water deliveries and stakeholders' proposed solutions, resulting in the December 2022 white paper-The Rio Grande/Rio Bravo Water Deliveries Under the 1944 Treaty: A Compendium of Ideas. It identified the following among proposals for expanding water supplies: salinity improvements and desalination; conservation (e.g., canal lining, aqueduct construction); and storage projects, both small and large, in Texas and in Mexico. Coorado R Iver U.S. delivery of Colorado River basin waters to Mexico is part of a broader allocation of basin waters pursuant to the Colorado River Compact, a seven-state agreement signed in 1923 that apportioned 7.5 MAF annually to both the Upper and Lower Colorado River basins in the United States and delineates how additional waters are to be sent to Mexico pursuant to a subsequent treaty. In the 1944 Water Treaty, the United States agreed to deliver to Mexico 1.5 MAF of Colorado River water per year, plus an additional 0.2 MAF when a surplus is declared. During drought, the United States may reduce deliveries to Mexico in similar proportion to reductions of U.S. consumptive uses. The 1.5 MAF obligation is generally split equally between Upper and Lower Basins. The United States typically has met its Colorado River delivery requirements to Mexico pursuant to the 1944 Treaty. Colorado River average flows have decreased significantly since 2000. During this time, the two countries have negotiated multiple minutes (e.g., Minute 319 in 2012, Minute 323 in 2017) that, among other things, reduced deliveries to Mexico under specified conditions and increased Mexico's ability to conserve and store water in U.S. reservoirs. Recent negotiations over future water curtailments in U.S. basin states have included speculation on the potential for similar changes for Mexico, although no new minutes have been announced. Since 1972 (Minute 240), deliveries of a portion of Mexico's Colorado River water have been provided to the Mexican city of Tijuana through U.S. diversions at Parker Dam, through Southern California and across the international border near San Diego. These diversions, typically account for a small portion of Mexico's total Colorado River apportionment (averaging 1,678 acre-feet per year from 2020 to 2024). They have been regularly extended over five-year increments and currently are authorized through 2027 (Minute 327). The deliveries must be requested by Mexico and approved annually by the United States. In March 2025, the United States denied