Last week, the Colorado River connected with the Gulf of California for the first time in 16 years when a high tide surpassed a sandbar Thursday, May 15.

Francisco Zamora, director of the Colorado River Delta Legacy Program for the Sonoran Institute, told LiveScience.com the river has barely reached the sea in 50 years. The Sonoran Institute recently dug a pilot channel to increase freshwater flow from the 1,450-mile river to the Gulf of California.

"After waiting for two months, it was very exciting to see," Zamora said. "This pulse flow opens the door for new possibilities for restoring riparian and estuary habitats."

Zamora's mission started 53 days ago with an international agreement called Minute 319. The pulse flow will be a five-year experiment that will also distribute one percent of the Colorado River's flow to bring back plants and animals that once lived in the river's outlet.

"Water was being released into the river... and all of this area got inundated," Zamora told Arizona Public Media (APM). "It was really exciting to see that happening.

"At that point we realized that if you bring water back into the delta it was feasible to restore some of these wetlands."

Jennifer Pitt, of the Environmental Defense Fund, said the U.S. began negotiating with Mexico seven years ago to work "on the delta on a collaborative, cooperative manner." The two countries struck an agreement with Minute 319 in 2012 and the pulse flow was one of the arrangements.

"We were able to persuade decision-makers in both countries that it was really time to turn the corner in the relationship and really try something different," Pitt told APM. "That instead of unilateral actions on either side of the border with no particular concern for impacts on the other side of the border it would be better to have a collaborative approach."

Zamora said the pulse flow is aimed at returning conditions to the way they were for thousands of years previously. No one knows how the Colorado River delta will fair even though the Mexico and U.S. are expected to continue their collaboration after Minute 319 expires in 2017.

"I do believe that it has demonstrated that with a small amount of water we can restore new habitat, new wetlands," Zamora said. "And it has also allowed the governments of the U.S. and Mexico to see that working together, we can make a difference."