The United States and Mexico share the waters of the Colorado River and Rio Grande pursuant to binational agreements. Increasing water demands and reduced supplies deriving from drought and air temperatures increase the challenges and significance of reliable water sharing. The International Boundary and Water Commission (IBWC) is charged with addressing issues that arise during application of binational water treaties. The IBWC is a binational entity with a U.S. Section that operates under foreign policy guidance from the U.S. Department of State. Under the binational 1944 Water Treaty, disputes and new developments can be resolved through agreed-upon interpretations of the treaty, called minutes. Mexican-U.S. relations generally grew closer during the George W. Bush and Obama Administrations. Water sharing was addressed through IBWC technical meetings and bilateral talks between government officials; these meetings and talks were the primary forum for addressing treaty compliance and frustrations of water users in Texas with Mexico's water delivery regime. Treaty minutes were used to enhance bilateral cooperation and provide flexibility in how treaty compliance was accomplished. It remains uncertain what principles will guide and what mechanisms will be used during the Trump Administration to address water conflicts and what role enhanced cooperation (e.g., measures similar to recent binational efforts in the Colorado River basin) may play in U.S.-Mexican water sharing. Colorado River. The Colorado River flows through seven U.S. states before reaching Mexico; 97% of its basin is in the United States. Under the 1944 Water Treaty, the United States is required to provide Mexico with 1.5 million acre-feet (AF) of Colorado River water annually. This figure represents about 10% of the river's average flow. Minute 319 is a set of binational cooperative measures in the Colorado River basin agreed upon in 2012. It provides for more cooperative basin water management, including environmental flows to restore riverine habitat. Minute 319 also provides for Mexico to share in cutbacks during shortage conditions in the basin; such cutbacks are not required under the 1944 Water Treaty. Under Minute 319, Mexico can delay its water deliveries from the United States under the 1944 Water Treaty and store its delayed deliveries in Lake Mead, thereby increasing the lake's elevation. Lake Mead elevation is the baseline used for determining shortage conditions and associated water delivery cutbacks for U.S. lower basin states. Minute 319 is to remain in force through December 31, 2017. It could be extended or replaced with a new minute, or it could be allowed to expire. Negotiations on a new minute were under way at the end of the Obama Administration. For the Colorado River basin, issues before Congress may be largely related to oversight of Minute 319 implementation, as well as developments in negotiations related to the future of Minute 319 or its successor (if any). Rio Grande. The Rio Grande is governed by two separate agreements. Deliveries to Mexico in the northwestern portion of the shared basin (near El Paso/Ciudad Juárez) occur under a 1906 convention, whereas deliveries for the southeastern portion (which is below Fort Quitman, TX) are laid out in the 1944 Water Treaty. Some Members of Congress have raised concerns about the adequacy of Mexico's water deliveries in the Rio Grande basin and the resulting economic impacts, especially in Texas border counties. During the 115th Congress, Members of Congress and other Texas stakeholders may continue their efforts to promote the adoption of mechanisms to achieve a Mexican water-delivery regime that provides more reliability and benefit for Texas.