"How to share water has long been a complex issue for the U.S.-Mexican border region, and it has been the cause of both tension and cooperation in the broader U.S.-Mexican relationship. The two countries share a nearly 2,000-mile border. Multiple rivers cross or form the border at various points. The principal shared river basins are the Colorado River and the Rio Grande. This report is a primer on U.S. and Mexican water sharing. It focuses on the sharing of surface waters. After presenting an introduction to U.S.-Mexican water sharing, this report describes the legal obligations and processes under the treaty on Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande (hereinafter Treaty or 1944 Water Treaty). It then describes developments in the Colorado River and Rio Grande basins."
CRS Report for Congress, R43312
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html