Colorado River Dam Opening for Flood Experiment

A Mexican channel that’s been dry for decades as cities and farms drink up the waters of the Colorado River will once again flow in an experiment to restore the region’s flora and fauna.

The gates of Morelos Dam, located a mile (1.6 kilometers) south of where California, Arizona and Mexico adjoin, will open March 23 to release a man-made flood, according to the Las Vegas Review-Journal reports. The flows will continue until May 18, and will be followed by a smaller stream of “base flows” meant to keep the channel wet as plants grow.

The so-called “pulse flow event” mimics the floods that happened each spring before the Colorado River was dammed up and its waters stored in reservoirs such as Lake Mead.

Water hasn’t flowed regularly to the Gulf of California since 1960, according to Jack Simes of the Bureau of Reclamation. Virtually no water gets past the Morelos Dam, which stops the flows and diverts them southwest to Mexico’s Mexicali Valley.

The pulse flow was authorized by a 2012 amendment to a 70-year-old treaty between the U.S. and Mexico. Water won’t be taken from the allotment Mexico gets annually from the Colorado River, but rather from “system credits” the country has earned by improving the efficiency of its water infrastructure.

Conservationists in both countries applauded the opening of the dam gates, which is expected to send water all the way to the Gulf of California once again, at least temporarily.

Osvel Hinojosa, Water and Wetlands Program Director for the conservation group Pronatura Noroeste, said about 380 bird species are expected to benefit from the new flow.

“So will the local Mexican farming communities that long-ago watched the Colorado River delta dry up,” Hinojosa said.