Some U.S. interests, particularly agricultural water users in Texas, have contended that Mexico's pattern of water delivery treats U.S. deliveries as a secondary priority to meeting Mexico's own water uses. These stakeholders see Mexico's use of wet-weather flows (e.g., excess flows after large storms) as reducing the reliability of U.S. water supplies from Rio Grande. The flexible five-year cycle for Mexico's Rio Grande deliveries at times is a frustration for U.S. water users in part because of the contrast with the more prescriptive nature of the U.S. water-delivery requirement to Mexico in the Colorado River (i.e., specified quantities are required to be delivered annually). Some interests have raised the possibility of renegotiating the 1944 Water Treaty.141
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https://www.everycrsreport.com/reports/R45430.html