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article imageColorado River returns to the sea in 'sacred reunion' of waters

By Karen Graham     May 22, 2014 in Environment
In what is being described as a "sacred reunion," the Colorado River has once again reached the waters of the Sea of Cortez (Gulf of California). The meeting of the sea and sediment-laden river is the result of a bi-national agreement years in the making.
On Thursday, May 15, with the help of a high tide surging over a sandbar, the river and the ocean were once again connected, said Francisco Zamora, director of the Colorado River Delta Legacy Program for the Sonoran Institute.
It was a great moment for conservationists who claim the Colorado River hasn't regularly flowed into the sea in over 50 years. The last time the river met with the sea was in 1998, according to National Geographic, or 1993, according to the Associated Press. Regardless of the date, it has been far too long.
The reunion of the waters of the Pacific Ocean and the mighty Colorado River is due to an international agreement between Mexico and the United States, known as Minute 319. Its purpose is to advance the restoration of the Colorado Delta by releasing a pulse flow, or artificial flood, after which sustaining base flows, or lower-level flows would continue in a five-year experiment.
On March 23, 2014, the gates of Morelos Dam on the Arizona-Mexico border were opened to allow the pulse flow of water into the Colorado River. "The pulse flow is about mimicking the way the Colorado River flowed in the springtime, thanks to snow-melt from the Rocky Mountains, before all the dams were built," says Sandra Postel, director of the Global Water Policy Project and a National Geographic Freshwater Fellow.
The Morelos Dam supplies water to the Mexicali region for irrigation.
The Morelos Dam supplies water to the Mexicali region for irrigation.
Historically, by the 1960s, so much of the Colorado River's water had been diverted because of dams such as Glen Canyon and the Hoover Dam, that little water was left to flow into the lower Colorado River. What little water that did make it to the Morelos Dam was diverted into Mexico's Mexicali Valley for crop irrigation. This left precious little water for wildlife and indigenous people who lived in the delta.
While authorities were worried whether or not the experiment would work, after 53 days, and traveling 100 miles, the water released from the Morelos Dam flowed through the delta and reached the gulf. Now that the "flood" is over, a lower-level base flow will continue through 2017 in an effort to restore several sites in the delta.
The amount of water used during the pulse flow and the eight-week period after was agreed upon by the U.S. and Mexico at 105,392 acre-feet of water (130 million cubic meters). This represents less than one percent of the pre-dam annual flow through the Colorado River.
Scientists are hoping the waters will restore some 70 miles (113 kilometers) of the river's course and more than 2,300 acres of floodplain, including freshwater marshes. At one time, the delta was a lush region that boasted two million acres of wetlands comprising one of the world's great desert aquatic ecosystems.
Colorado River Dry Delta  terminus of the Colorado River in the Sonoran Desert of Baja California an...
Colorado River Dry Delta, terminus of the Colorado River in the Sonoran Desert of Baja California and Sonora, Mexico, ending about 5 miles north of the Sea of Cortez (Gulf of California). Photo taken: Jan. 12, 2009.
Pete McBride, U.S. Geological Survey
Today that same region has less than 10 percent of its vegetation remaining because of the scarcity of water, and more recently, severe bouts of drought. Restoration of vegetation will benefit wildlife, including endangered birds such as Yuma clapper rails, Virginia rails, and California black rails.
The truly significant thing behind the Minute 319 agreement is the that this is the first time that two countries have joined together to allocate water specifically to benefit the environment in a cross-border setting. Postel says that while the Colorado River Delta may never return to its former size, "but we know that if you add some water, life does return. We've seen rivers running dry all around the world, from being dammed and diverted, and here's one ecosystem of great significance that two countries are working cooperatively to try to restore. So many others need restoration too."
More about Colorado river, sea of cortez, Pacific ocean, minute 319, deltas and estuaries
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