Binational Issues and Activities with Mexico


The United States works closely with Mexico through the International Boundary and Water Commission (IBWC) to implement the 1944 U.S.-Mexico Water Treaty, including through the extensive use of Minutes to address specific treaty implementation issues that arise. Along with other stakeholders, CRB facilitates development, implementation, and/or oversight of the 1944 Water Treaty both generally and as Minute oversight Work Group members.


Under unimpaired conditions, the Colorado River naturally flows from the United States into Mexico and the Gulf of California (Sea of Cortez). With the development of water use activities in the United States in the early 20th century, it appeared likely that eventually as much water as possible would be diverted for use within the U.S., with only excess water or return flow continuing to Mexico. Transboundary water issues similarly existed in the other rivers shared between the United States and Mexico, including the Rio Grande and Tijuana Rivers.

The 1944 U.S. Mexico Water Treaty, formally called the “Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande” and often shortened as the “1944 Water Treaty”, addresses U.S.-Mexico transboundary water management. Under the 1944 Water Treaty, the U.S. is obligated to deliver 1.5 MAF of Colorado River water of sufficiently low salinity annually to Mexico. The treaty is implemented by the International Boundary and Water Commission (IBWC), which has a U.S. Section and a Mexico Section, with implementation agreements achieved through the use of IBWC Minutes. Note that the IWBC and the Minutes system is established by the treaty itself.

Major Minutes related to the delivery of Colorado River water to Mexico are addressed in Minute 242, Minute 319, Minute 323, and Minute 330. Many other minutes related to the Colorado River exist, and may be found by searching for Colorado River projects on IBWC’s Minutes by Project (for example, search for “Colorado River deliveries”).

Minutes are supported through the oversight activities of binational Work Groups, in which CRB participates on behalf of the State of California. Currently, Work Groups exist for oversight of Minute 323, including:

  • Environmental Work Group
  • Hydrology Work Group
  • Projects Work Group
  • Desalination Work Group