Over the past hundred years, people have introduced dozens of non-native fish species into the Colorado River and its tributaries. During that time, populations of native fish species have dropped, in some cases dramatically. It’s easy to guess at the causes of native species decline, like predation and competition for food. But it’s far more difficult to prove.
Mexico and the United States are working toward a broad package deal that would help revive the Colorado River Delta.
Seven years ago, the U.S. began working on the project to line an earthen portion of the All-American Canal in Imperial Valley and send the saved water to San Diego. Many in Mexico and the U.S. opposed the lining, saying it prevented seeping water from reaching fields and wetlands in Mexico. The lining project was completed in 2010.