LOS ALGODONES, Mexico - Colorado River water has begun pouring over a barren delta near the U.S.-Mexico border, the result of a landmark bi-national agreement being celebrated Thursday.
The gush of water in Mexico is an effort to revive the last 70-mile stretch of the river into the Sea of Cortez. The delta dried up decades ago.
Conservationists hope the water will bring back trees, wildlife and aquatic life that were once abundant in the region when it was teeming with water decades ago.
The river's most southern dam - Mexico's Morelos Dam, near Yuma, Ariz. - on Sunday began unleashing 105,392 acre-feet of water, enough to supply more than 200,000 homes for a year. The one-time release is expected to last until May 18.
The flow was expected to intensify and reach a peak Thursday of an additional 4,200 cubic feet per second.
"You just see visually quite clearly a much larger volume of water in the river and there's quite a buzz about it," said Terry Fulp, regional director of the Lower Colorado Region for the U.S. Bureau of Reclamation.
A handful of officials from the U.S. and Mexico governments were on hand to celebrate the flow Thursday just across the border from Yuma. An estimated 400 people attended the event, said Jack Simes of the Bureau of Reclamation.
"The pulse flow now underway is the first major step in a series of anticipated actions and cooperative measures outlined between our two countries," said Assistant Secretary of the Interior for Water and Science Anne Castle. "Today's event celebrates our shared vision to work together as partners to address the resources of the Colorado River and its parched delta."
Farms, businesses and homes in seven U.S. states - Arizona, California, Colorado, Nevada, New Mexico, Utah, Wyoming - rely on the Colorado River, as do the Mexican states of Baja California and Sonora.
In 2012, the two countries that share the river water agreed on ways to share the pain of droughts and bounty of wet years, a major amendment to a 1944 treaty. Part of that agreement called for restoration of the Colorado River delta.
"Today we are witnessing what appears to be a paradigm shift in the way we manage water," said Jennifer Pitt, director of the Colorado River Project, who helped negotiate the one-time flood. "Historically in the West, everyone has approached water with an 'us against them' mentality. Now we're talking about how we can share water, conserve water, and invest in new water projects and the health of the river itself. It's truly refreshing."
The release of water was aided through water conservation projects by the U.S. and Mexico, according to the International Boundary and Water Commission. Officials from those two countries were scheduled to be at the Morelos Dam on Thursday for an event to mark the restoration effort.
Experts will monitor the flood to determine its effects on the environment.