Millions of gallons of water carried by the Colorado River pass through the turbines of the Hoover Dam near Las Vegas every day, generating electricity for hundreds of thousands of American homes.
Posted at 6:28
But the chronic drought that has plagued the western United States for years has reduced the volume of the reservoir so much that the hydroelectric plant may soon be out of service.
“We are on the 23rde Year of drought here in the Colorado River Basin, and Lake Mead has dropped to 28% of its capacity,” said Patti Aaron of the Bureau of Reclamation, the federal agency that manages the dam.
“There’s not that much pressure left to push the water through the turbines, so efficiency drops and we can’t produce as much energy,” she continues.
At the time of its construction, the Hoover Dam was a symbol of American ambition and the skill of its engineers. The work, begun in 1931 in the midst of the economic crisis, had mobilized thousands of workers who sweated 24 hours a day to build what was then the largest dam in the world.
The work blocks the Colorado River and leads to Lake Mead, which remains the largest reservoir in the United States to date.
At its highest point, the lake reached 365 meters above sea level, but after more than twenty years of drought, it is now at 320 meters, its lowest level since filling.
The lake is currently losing about a foot each week. If it falls below 289 meters, the dam gates are no longer flooded and the turbines stop.
“We are working very hard to ensure that this does not happen,” emphasizes Mr.me Aaron.
The Colorado River rises in the Rocky Mountains and meanders more than 1,400 miles through Colorado, Utah, Arizona, Nevada, California and then northern Mexico, where it – increasingly painfully – empties into the sea.
It is fed primarily by snow that accumulates at high altitudes in winter before gradually melting in the warmer months.
But under the influence of climate change, rainfall is decreasing and snow is melting faster, depriving the river of some of its resources that provide water to tens of millions of people and many farms.
Boaters on Lake Mead, many from Las Vegas and surrounding cities, say they are doing their best to conserve the water.
They cite the succulents they replaced their lawns with and the great effort desert cities are making to recycle water in homes.
“But you have farmers in California who grow almonds for export,” complains Kameron Wells, who lives in nearby Henderson, Nevada.
In Southern California, millions of homes are now forced to limit garden watering to just one or two days a week.
But in the Nevada desert, huge mansions continue to be built just outside Las Vegas, and green golf courses seem to emerge from the dry and dusty landscape.
” Out of sight out of mind ”
For Stephanie McAfee, a climate researcher at the University of Nevada at Reno, the American West has always had this unlikely side. “The average rainfall in Las Vegas is about four inches per year,” she told AFP.
“In order for big cities like Las Vegas, Phoenix or Los Angeles to exist, we use the water that falls in the form of snow in the much wetter and more remote western regions,” adds the scientist.
In terms of climate, the drought of the past two decades is not that rare, she says. But “what’s happening now is that we have a drought and temperatures that are much warmer and when the temperatures are high everything dries out faster”.
“It is the consequence of climate change fueled by greenhouse gas emissions from human activities. »
On Lake Mead, boat salesman Jason Davis maneuvers his boat toward the gigantic Hoover Dam, whose flanks are ringed with mineral deposits, a testament to the level the water reached a few years ago.
For him, the plant is less a generator of electricity than a landscape that needs to be protected.
“People who haven’t come can’t realize it. It’s “out of sight, out of mind”. But we use too much water,” he says. “Until you see these rings, you cannot understand the problem.”