Background: The headwaters of the Colorado River are in La Poudre Pass in Colorado and the river flows through seven states, across the Mexico border, and out to sea, or at least it used to. Now so much water is being diverted to thirsty cities, crops, and livestock that by the time the river reaches the Mexican border, often there is no water left. This was hard for farmers south of the border. In 1944 the United States signed a treaty with Mexico agreeing to leave about 58 cubic meters per second of water in the river when it crossed the border. That volume of water is equivalent to about five cement mixer trucks of water per second.

The graph shows the discharge of the Colorado River at the Mexico border in cubic meters of water per second. The dotted line shows the level of discharge agreed to in the treaty.

Data Source:  and