For the first time in almost 20 years, the Colorado River is flowing into northern Mexico, and through a dam that usually stops it.
It's part of an agreement between the Mexican and U.S. governments, as well as non-profits in both countries. It's called a pulse flow, meaning a temporary release of water.
KJZZ's Stina Sieg recently traveled across the border to see the effect it's having on Mexico's long-barren delta.