Why are they flooding the Grand Canyon?

Grand Canyon
CC BY 2.0 Grand Canyon National Park/Flickr

The U.S. Department of the Interior has taken to releasing massive amounts of the Colorado River from dams, here's why.

The Colorado River should reach the sea, that’s what it wants to do. It wants to start in the Rocky Mountains and wind its way 1,450 miles along the Arizona-California border into the Mexican delta, irrigating farmland and nourishing loads of wildlife and flora along the way before emptying itself into the Gulf of California. That’s what it did up until 1998. But then, gradually, ouch.

The mighty Colorado continues to take top honors in American Rivers' annual ranking of America’s most endangered rivers. The conservation groups notes, “A century of water management policies and practices that have promoted wasteful water use have put the river at a critical crossroads.” Demand on the river’s water simply exceeds its supply, to the point that it no longer reaches the sea. Instead, it dribbles into nothingness somewhere in the desert of the Southwest.

As Jonathan Waterman wrote in The New York Times about the river no longer reaching its natural destination in Mexico:

Now dozens of animal species are endangered; the culture of the native Cocopah (the People of the River) has been devastated; the fishing industry, once sustained by shrimp and other creatures that depend on a mixture of seawater and freshwater, has withered.

The river’s sad story began in 1922 with the Colorado River Compact, an agreement among seven western states to divvy up its bounty. Mexico was allotted 10 percent of the flow. Almost a century later and a study by the U.S. Department of Interior’s Bureau of Reclamation finds that the entire river and its tributaries are siphoned off to meet the needs of 40 million Americans living in Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming. Along with hydrating 5.5 million acres of land, it also helps power much of the electricity that comes from hydro-power plants.

Did I say ouch? Ouch. And while the main river’s 15 dams (and hundreds more on tributaries) hydrate people and supply power for millions, they also stymy ecosystems. One feature which has been notably suffering is the river’s sandbars and beaches which are disappearing due to a lack of sediment; sediment which is held in dams along with the river's water. These features used to provide habitat for fish and protect archeological sites.

But then came the “high-flow experiment,” (HFE as the U.S. Department of the Interior calls it), a plan to release some of the sediment which the dams are retaining by means of controlled flooding. This met resistance from the power companies because it meant lost revenue; but the importance was deemed necessary and the first trial release occurred in 1996. And they have continued. In one flood in November of 2013 flood from the Glen Canyon Dam, 34,100 cubic feet per second was released for 96 hours. The rush of water took almost a week to course down the canyon.

Now, a team of researchers have detailed the success of HFE in a study, saying that indeed, the plan is working. “The releases appear to be achieving the desired effect. Many sandbars have increased in size following each controlled flood,” the study authors note, “and the cumulative results of the first three releases [from the Glen Canyon Dam] suggest that sandbar declines may be reversed if controlled floods can be implemented frequently enough.”

However, now we have a drought and the idea of releasing that much water is difficult; the releases are decreasing as the dam engineers hold back water. Climate change has also been altering seasonal thunderstorm activity, notes Smithsonian.

Still, the researchers are carefully optimistic, saying, "Although long-term success cannot be predicted, the early results of HFE attempts to maintain the Grand Canyon’s sandbars show promise." Now if only they could manage to get the river back to the sea, where the delta and estuaries along the way could use some promise of their own.

Why are they flooding the Grand Canyon?
The U.S. Department of the Interior has taken to releasing massive amounts of the Colorado River from dams, here's why.

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