Friday, March 21, 2014

A Man-Made Disaster in the American Southwest

By Terrell Johnson
From Weather.com

Nearly a century ago, the waters of the Colorado River flowed freely through the Mexican border town known as San Luis Rio Colorado, a place where you could catch a steamboat that would take you upstream as far as Yuma, Ariz., or even pull a fish from the river as big as a man’s arm.
The Colorado made its way here after snaking across more than 1,400 miles of the North American continent, tumbling over waterfalls among the snow-covered Rocky Mountains and cascading through canyons in Arizona, coursing all the way through high plains and deserts to the Gulf of California, where it once fanned out in a delta that teemed with wildlife.
But today, there’s nothing left of the riverbed here but some hardscrabble desert plants and an ocean of dry sand. What was once an estuary where trees, birds and countless varieties of marine life made their home, now thousands of parched, lifeless acres lie baking in the open sun, the only things left in a region starved for water.
That’s because the Colorado has been dammed and diverted in so many places that the river – which flowed from its headwaters high up on the Continental Divide to the Gulf for more than six million years – now slows to a trickle and dries up long before it reaches the sea.
“They call the Colorado the ‘mother of rivers,’ because all these rivers flow out of it and none flow into it,” says Kara Lamb, a public information officer with the U.S. Bureau of Reclamation, the federal agency that manages water resources across the western states. “The truth is, she’s a working mother. Almost all of her rivers are dammed and utilized.”
What has happened in San Luis Rio Colorado isn’t an accident. It’s the result of a series of choices made over decades, choices that stuck more and more straws into the river in order to prioritize the growth of large urban areas and agriculture in the southwestern United States over the needs of the natural environment.
The water those straws have siphoned away has been instrumental in building the majestic skylines of cities like Los Angeles, Phoenix and Denver, and in turning what were once semi-arid regions in places like Arizona and California’s Central Valley into agricultural behemoths that today supply roughly 15 percent of the nation’s food.
And without them, there would be no glittering lights on the Las Vegas Strip, no Denver football stadium for the NFL’s Broncos, no seaside parks and restaurants overlooking San Diego Bay, and no Universal, Paramount or Warner Brothers movie studios in Los Angeles.
But perhaps Mother Nature never meant for tens of millions of people to live in a region where many cities’ average yearly rainfall is measured in single digits.
The more than 30 million people who depend on the river for their drinking water could certainly be forgiven for thinking so, people who live in a place where nearly a decade and a half of searing drought has left the Colorado at 40 percent of its normal streamflow for the past two years.
“We’ve never had two back-to-back years that low before,” says Scott Huntley, a spokesman for the Southern Nevada Water Authority, which manages the water needs of Las Vegas and several nearby cities and districts.
The drought is forcing communities that depend on the river in the U.S. – which collectively use up roughly 90 percent of the river’s water – to confront the fact that there may be limits, after all, to what humans can extract from the ecosystems that make their lives possible.
Meanwhile down the river in Mexico, a small miracle is set to take place this week. Thanks to some changes to a 70-year-old treaty between the U.S. and Mexico, the Colorado will reach the sea again for the first time in nearly 15 years on March 23, when the gates of Mexico’s Morelos Dam are opened to release a man-made flood onto the mud flat that was once the Colorado Delta.
This pulse flow will be repeated for roughly two months until mid-May, to mimic the flows of the floods that occurred here every spring until the 1960s and spread native plant seeds and soil, creating the conditions that made it possible for plants to grow.
The human-engineered flows are designed to be “high enough to rise out of the riverbanks onto the area where the trees grow … and ensure that any seedlings continue to grow,” said Jennifer Pitt, the director of the Environmental Defense Fund’s Colorado River Project and U.S. co-chair of the group that helped negotiate the pulse flow accord.
Famed explorer Alexandra Cousteau will report for The Weather Channel’s “AM:HQ” throughout this month on the progress of the pulse flows and the history of the river itself, tracing the path of the Colorado all the way from its headwaters in today’s Rocky Mountain National Park to the delta, where water will be flowing for the first time in years.

No comments:

Post a Comment