Phoenix

Epic drought tests Hoover Dam as water levels in Lake Mead plummet

BOULDER CITY, Nev. — Hoover Dam towers greater than 700 ft above Black Canyon on the Arizona-Nevada state line, holding again the waters of the Colorado River. On prime of the dam, the place guests peer down the sleek white arc of its face, one in every of its artwork deco-style towers is adorned with a murals that memorializes the needs of the dam.   

In 5 aid sculptures by Oskar Hansen, muscular males are proven gripping a ship’s wheel, harvesting an armful of wheat, standing beside cascading water and lifting a heavy weight overhead. With the concrete figures are phrases that encapsulate why the dam was constructed, as laid out in a 1928 law: FLOOD CONTROL, NAVIGATION, IRRIGATION, WATER STORAGE and POWER.

Eighty-six years after its completion in 1935, the infrastructure at Hoover Dam continues doing what it was designed to do: holding water and sending it coursing by way of consumption tunnels, spinning generators and producing electrical energy. But the foundations for managing the river and dividing up its water — which had been laid down practically a century in the past beginning with the 1922 Colorado River Compact and which have repeatedly been tweaked — at the moment are going through the best strains for the reason that dam was constructed. 


The results of years of extreme drought and temperatures pushed higher by climate change are strikingly seen alongside Lake Mead’s retreating shorelines close to Las Vegas, the place the rising “bathtub ring” of whitish minerals coats the rocky desert slopes.

Since 2000, the water stage in the reservoir, which is the biggest in the nation, has dropped about 140 ft. Lake Mead is now simply 37% full, headed for a first-ever official shortage and sinking towards its lowest levels because it was stuffed. 

One of the driest 22-year durations in centuries is colliding with the river’s power overuse. As the reservoir falls towards file lows, its decline threatens the water provides of cities and farmlands, and divulges how the system of managing water in the desert Southwest faces rising dangers. 

A high-water mark or “bathtub ring” is seen on the shoreline of Lake Mead at Hoover Dam.
A high-water mark or “bathtub ring” is seen on the shoreline of Lake Mead at Hoover Dam.
A high-water mark or “bathtub ring” is seen on the shoreline of Lake Mead at Hoover Dam.
Mark Henle/The Repbulic

On prime of the dam, the place sidewalks run alongside the curving parapet, the views are dominated by 4 consumption towers that protrude from the water. Each of the dam’s two large spillways, the place water final ran in 1983, sits dry and empty, resulting in a gaping 50-foot-wide tunnel. 

In a room with giant home windows overlooking the consumption towers, Mike Bernardo of the federal Bureau of Reclamation begins a tour of the dam. He and Patti Aaron, a bureau spokesperson, have agreed to take me and Arizona Republic photojournalist Mark Henle inside to point out us how the dam works and clarify what the decrease water levels will imply over the approaching year.

Bernardo leads a group of engineers and hydrologists who plan water releases from Hoover Dam, as properly as Davis and Parker dams downstream, sending flows that journey by way of pipelines and canals to Phoenix, Los Angeles and farmlands in the U.S. and Mexico that produce crops such as hay, cotton, grapes and lettuce.

Bernardo’s group additionally units energy technology objectives and produces a month-to-month report with the most recent projections of how reservoir levels will possible change over the subsequent 24 months. Lately, every month’s report has introduced worsening numbers. Predicted water-level declines have grown as estimates of inflows into Lake Powell, the upstream reservoir, have shrunk resulting from extraordinarily parched conditions throughout the higher watershed in the Rocky Mountains, the place a lot of the river’s movement originates as melting snow.

“Unfortunately, due to how dry things have been,” Bernardo says, “what we’re seeing is Lake Powell’s elevations are dropping.”

And that can imply much less water flowing into Lake Mead for the remainder of the year. The previous 12 months have been among the many driest on record throughout the Colorado River Basin. Inflows into Lake Powell from April by way of July are estimated to be simply 26% of the long-term average, and that’s resulting in fast declines in each Powell and Mead, the 2 largest items of the river’s water-storage system. 

The heat, dry circumstances over the previous two years have baked the watershed’s soils to such an extent, Bernardo says, that “when the snowmelt starts to run off, it just gets sucked up into the ground like a sponge.”

But the calls for for water downstream from Hoover Dam proceed. And with the Southwest’s farmlands in peak irrigation season by way of June, Bernardo says, Lake Mead’s floor is dropping about 1 foot every week.

Mike Bernardo of the federal Bureau of Reclamation, at Hoover Dam in May 2021.

Mike Bernardo of the federal Bureau of Reclamation, at Hoover Dam in May 2021.
Mark Henle/The Republic

The reservoir has declined greater than 16 ft over the previous year and is forecast to fall about 9 ft extra by the tip of this year.

The latest projections present that by the tip of 2021, Lake Mead will decline under an elevation of 1,066 ft, far under the edge — 1,075 ft — for the federal authorities to declare a scarcity. That’s anticipated to occur in August, triggering the largest water cuts to date subsequent year for Arizona, Nevada and Mexico.

Even bigger cutbacks may come in 2023 if the reservoir continues to decline as projected over the subsequent year right into a extra extreme “Tier 2” scarcity.

Lake Mead’s downward spiral is being pushed largely by the dire state of affairs upstream at Lake Powell, which has declined to 34% of full capability.

“We need three to four consecutive years of above-average inflow, snowpack runoff and inflow into Lake Powell, to refill these reservoirs,” Bernardo says. “So that’s what we’re hoping for.”

The Colorado River naturally cycles by way of wet and dry durations. But over the past 22 years, the watershed has had 17 dry years, Bernardo says, and solely 5 years with above-average or moist circumstances.

With local weather change, hotter temperatures have been evaporating extra moisture off the panorama and leaving much less flowing in the river and its tributaries. Scientists describe it as a “megadrought” and one which, in contrast to the lengthy droughts of the previous, is being amplified by carbon air pollution and the heating of the planet.

One of the unknowns going through the officers who handle Colorado River water is simply how severely the reservoirs might be affected by climate-driven “aridification” in the years to come back. But some scientists have estimated the river may lose roughly one-fourth of its flow by 2050 as temperatures proceed to rise, and that for every extra 1 diploma C (1.8 levels F) of warming, the typical movement is likely to drop by about 9%.

“With the warmer temperatures,” Bernardo says, “not only do we see things melt off quicker but you have that rising snow line, which creates less inflow.”

The Overton Arm of Lake Mead at Lake Mead National Recreation Area, Nevada. The reservoir has declined dramatically since 2000.

The Overton Arm of Lake Mead at Lake Mead National Recreation Area, Nevada. The reservoir has declined dramatically since 2000.
Mark Henle/The Republic

The declines in the reservoirs have accelerated over the previous two years.

In 2019, representatives of Arizona, Nevada and California agreed beneath a deal referred to as the Drought Contingency Plan to share in water reductions by way of 2026 to scale back the dangers of Lake Mead falling to critically low levels. The settlement requires progressively larger cutbacks if Lake Mead continues to drop under decrease set off factors in the approaching years.

If the reservoir drops under 1,045 ft, California would begin to take cuts. And Mexico is already contributing by leaving some water in Lake Mead.

“These mechanisms have been put into place to protect these reservoir elevations,” Bernardo says.

While the most recent settlement is meant as a brief stopgap measure, officers from the seven states that rely on the river are making ready to barter new guidelines for managing shortages after 2026. And these talks promise to be harder.   

“The biggest challenge is how the future water officials will look at that imbalance of the actual water that’s coming into the reservoirs now, and use that information and plan for the future,” Bernardo says.

In the meantime, he says, the bureau’s obligations in managing the dams and water deliveries stay the identical. And that features incorporating the most recent science and fashions, and offering up-to-date data to representatives of the states, water districts, tribes and different entities alongside the river, Bernardo says, “to communicate what’s going on and what we’re seeing, so everyone can act proactively.”

“When you have a river system like this, a complex reservoir and river system especially, that is experiencing the hydrology that we’ve been seeing, and such a quick decline in the Upper Basin over these last two years, transparency and communication is key,” Bernardo says.  

Leaving the room overlooking the lake, Bernardo leads us alongside the sidewalk and right into a tower, the place golden elevator doorways roll open. 

We step in and descend into the stomach of Hoover Dam.

Patti Aaron, with the Bureau of Reclamation, is reflected in elevator doors, May 11, 2021, at Hoover Dam.

Patti Aaron, with the Bureau of Reclamation, is mirrored in elevator doorways, May 11, 2021, at Hoover Dam.
Mark Henle/The Republic

Iconic dam holds much less and fewer

Bernardo is 35 and has labored for the Bureau of Reclamation for practically a decade, together with the final two years as river operations supervisor. A mechanical engineer who grew up in New Jersey, he normally works together with his employees on the company’s office in Boulder City, Nevada, however he additionally usually drives out to go to the dam, generally to guide particular excursions.

Whenever he rounds the curve in the canyon and sees the dam, Bernardo says, he feels awestruck and “the hair still sticks up on my arms.”

“It never gets old,” he says. “I’m wowed by the engineering marvel.”

Part of that comes from understanding the historical past of all that went into the dam’s design and building through the Great Depression, from the hand-drawn blueprints to the blasting with dynamite, the railroad that carried provides, and the large quantities of concrete that had been poured in, making a dam that’s 660 ft thick at its base — practically as thick between the reservoir and the downstream facet as it’s tall. (According to the Bureau of Reclamation, Hoover Dam contains enough concrete to build a sidewalk 4-feet extensive across the complete Earth on the equator.)

Whenever he visits the dam, Bernardo says, its historic significance can be inescapable: the way it managed the Colorado’s floods, opened up arid lands for farming and fed the rise of cities throughout the Southwest. As he describes it, the dam “helped nourish our nation” and helped the West thrive.

“We like to show it off,” he says.

Bernardo is steeped in numbers and rattles off particulars about river flows, the dam, the volumes of water launched and the quantities of hydroelectricity generated.

With greater lake levels, Hoover Dam’s regular capability is 2,074 megawatts, he explains, producing sufficient energy per year to produce roughly 450,000 common households. But at immediately’s lake stage, the dam’s capability has decreased about 25% to 1,567 megawatts, and it’s producing sufficient energy for roughly 350,000 properties.

With each foot the lake declines, about 6 megawatts of power-generating capability is lost. The lowest stage at which Hoover may produce energy is about 950 ft, with an anticipated capability of 650 megawatts. If the lake had been to fall under that time — a state of affairs the present guidelines are geared towards avoiding — the dam would now not have the ability to generate energy.

Wearing hardhats, we stand going through a row of colossal mills in the ability home on the Arizona facet of the dam. Each one weighs greater than 4 Boeing 747-400 jets. On their sides are plaques itemizing the producers: Westinghouse, GE, I.P. Morris and Allis-Chalmers. The oldest mills have been working since 1936.

Inside every generator, Bernardo says, a rotor weighing 1.2 million kilos spins at 180 revolutions per minute.

The water flows in by way of consumption towers, comes jetting by way of beneath excessive stress and spins the generators, producing electrical energy. Only two of the 9 generators on the Arizona facet are spinning in the meanwhile to satisfy energy calls for, however the chamber nonetheless hums with the rumble of whirring metallic.

Bernardo steps near a generator and places a hand on one in every of a number of spherical home windows containing oil. It’s heat from circulating by way of the equipment.

Bernardo is fascinated by the mechanics of the dam, together with its custom-made components and instruments, such as particular wrenches practically 4 ft in size. When a bolt must be changed, he says, it have to be fabricated from scratch.

He’s additionally studied the information on water levels, inflows and releases to a degree that he can describe off the highest of his head how releasing a specific amount of water will have an effect on Lake Mead.

“Every 85,000 acre-feet is equivalent to one foot in elevation in Lake Mead right now at the current elevations,” Bernardo says.

The generator/turbine gallery on the Arizona side, May 11, 2021, at Hoover Dam, on the Arizona/Nevada border.

The generator/turbine gallery on the Arizona facet, May 11, 2021, at Hoover Dam, on the Arizona/Nevada border.
Mark Henle/The Republic

But as the reservoir continues to say no, releasing that very same quantity of water yields an even bigger drop in lake stage.

“That’s one of the concerning pieces,” Bernardo says. “The reservoir is shaped, we call it a teacup, but more like a martini glass. And the lower the elevation goes, the faster the rate of decline.”

That dynamic additionally impacts how a lot the deliberate water cuts may also help Mead’s stage. Under a first-tier scarcity subsequent year, for instance, Arizona, Nevada and Mexico are making ready for cuts totaling 613,000 acre-feet, which Bernardo says is equal to 7-8 ft in Lake Mead.

If the reservoir had been to drop by way of decrease scarcity levels to under 1,025 ft, the full cuts among the many three states and Mexico would add as much as greater than 1.3 million acre-feet. That quantity, Bernardo says, would equal practically 20 ft conserved in Lake Mead at these low levels.

When representatives of California, Arizona and Nevada had been negotiating the deal, they selected 1,025 ft as a threshold to keep away from, and one they thought the lake can be unlikely to succeed in. The settlement additionally features a backup provision. If the two-year projections present Mead is prone to decline under 1,030 ft, the agreement says the states and the Interior secretary “shall consult and determine what additional measures will be taken.”

The authorities’s newest five-year projections, utilizing an method that considers the river’s lower flows over the past three decades, estimates a 25% likelihood of Lake Mead declining under 1,025 ft in 2025.

Much may change, although, with a snowy winter in the mountains.

“We hope and we feel very strongly that the measures that have been put into place should slow down the decline,” Bernardo says. “Now, if it’s enough to make it recover, your guess is as good as mine, because the hydrology has been so bad.”

But if the river basin will get a moist year with common flows, Bernardo says, the cutbacks in the present plan “will buy us time to get to the next year, in hopes to get a better water year.”

“And I think that’s what the system is designed to do,” he says.

An ‘Era of Limits’

The outlook for the Colorado River has grown more and more dire over the previous a number of years. In one study, scientists discovered that about half the trend of decreasing runoff in the Upper Colorado River Basin since 2000 was resulting from unprecedented warming.

Other researchers warned in a report this year that an “incremental approach to adaptation” is unlikely to be sufficient in the long run. They identified that flows from 2000 by way of 2018 had been about 18% lower than the twentieth century common and stated the downward pattern will possible proceed as temperatures rise with local weather change.

Worries about overusing the river predate the present dry spell. In truth, some early warnings got here earlier than the authorized framework that divided the Colorado among the many seven states and Mexico.

John Wesley Powell famously voiced considerations in 1893, some 24 years after his expedition down the river in the Grand Canyon, when he informed the attendees on the International Irrigation Congress in Los Angeles: “I tell you, gentlemen, you are piling up a heritage of conflict and litigation over water rights, for there is not sufficient water to supply these lands.”

Under the 1922 Colorado River Compact and subsequent agreements, the river has lengthy been severely overallocated. As University of Arizona regulation professor Robert Glennon has succinctly put it, “there are more water rights than there is water.”

So a lot has been diverted that almost all of the river’s delta in Mexico was reworked many years in the past into stretches of dry riverbed that wind by way of farmlands and desert in the Mexicali Valley. Only a smattering of natural wetlands stay.

In his 1986 ebook “Cadillac Desert,” Marc Reisner wrote that Hoover Dam “rose up at the depths of the Depression and carried America’s spirits with it. Its electricity helped produce the ships and planes that won the Second World War, and its water helped grow the food.”

But Reisner wrote that from these hopeful beginnings, “the tale of human intervention in the Colorado River degenerates into a chronicle of hubris and obtuseness” and that individuals in the river basin — at the moment solely 20 million — “will probably find themselves facing chronic shortages, if not some kind of catastrophe.”

“One could say that the age of great expectations was inaugurated at Hoover Dam,” Reisner wrote. “And one could say that, amid the salt-encrusted sands of the river’s dried-up delta, we began to founder on the Era of Limits.”

More not too long ago, authors Eric Kuhn and John Fleck wrote in their 2019 ebook “Science Be Dammed: How Ignoring Inconvenient Science Drained the Colorado River” that “even absent climate change, we would be in trouble” and that the present issues surrounding the river “are the inevitable result of critical decisions made by water managers and politicians who ignored the science” as early as the Twenties.

They discovered that in 1925, U.S. Geological Survey scientist Eugene Clyde LaRue had “tallied what was known at the time about the river’s flow, potentially irrigable farmland, and growing cities, and concluded that if we built the dams and canals to use all the water being allocated on paper in the 1920s to meet all the anticipated demand, the Colorado River would be in deficit.”

Two different scientific analyses in the Twenties reached the identical conclusion, Kuhn and Fleck wrote, however the scientists’ warnings had been ignored, and that “set in motion decades of decisions that would end in the overuse seen today.”

suggested that addressing the river’s deficit would require recognizing that the “over-allocation became embedded in basin rules in very specific ways that remain unresolved” and must be mounted.

Negotiating the post-2026 guidelines shall be difficult for everybody concerned, Kuhn and Fleck wrote, and a few of the elementary points going through negotiators now are just like these a century in the past, together with questions of how a lot water the river will present in the years forward, and the way the system must be ruled amid uncertainty.  

The Colorado River Basin wants “a stable and effective governance of the use of the river’s waters under conditions where current demands already exceed the exiting supplies,” Kuhn and Fleck wrote. “Like one hundred years ago, the river’s future is not all dark. Innovation, cooperation, and an expanded reliance on science are now the foundation for basin-wide solutions.”

One effort to revive a few of the wetlands and ecosystems in Mexico started this month, as water started flowing into the delta under an agreement between the U.S. and Mexican governments. The water releases in the delta, which can whole 35,000 acre-feet between May and October, are meant to nourish vegetation and wildlife at habitat restoration websites the place conservation teams have planted cottonwoods and willows.

The inflow of water is meant to imitate a small portion of the floods that after swept throughout the delta towards the Sea of Cortez. This year’s releases quantity to a smaller model of a deliberate flood that coursed by way of the delta in 2014. In that “pulse flow,” 105,000 acre-feet of water brought back a flowing river in areas that had been dry since floods in the late Nineties.

The releases in the delta this year, utilizing water beforehand saved in Lake Mead, quantity to simply 5 inches of water in the reservoir. Much extra of the water that passes by way of Hoover Dam is pumped to Phoenix, Tucson and Los Angeles, and flows by way of canals to irrigate farmlands alongside the river from Parker to Yuma, and throughout the Coachella, Imperial and Mexicali valleys.   

The intake towers on the Arizona side, May 12, 2021, at Hoover Dam, on the Arizona/Nevada border.

The consumption towers on the Arizona facet, May 12, 2021, at Hoover Dam, on the Arizona/Nevada border.
Mark Henle/The Republic

Low water levels convey dangers

As we proceed by way of the innards of Hoover Dam, the polished terrazzo flooring and hallways give solution to a dim tunnel, which cuts into the canyon wall. Its ceiling and sides are rough-hewn jagged rock resembling a mineshaft.

Stopping, Bernardo holds his cellphone and factors its mild at a spherical gap in the tunnel wall.

“They would load it up with dynamite and they’d blast,” he says. “Drill it in, put the dynamite, blast it, remove the debris, over and over again.”

In locations, the tunnel partitions are moist. Dripping water dribbles down the rocks.

“All dams have seepage, no matter where they are. We never call it a leak because it’s not a leak. It’s just seepage, the natural process,” Bernardo explains. The water seeps from the lake by way of cracks in the rock and is routed to drains and a sump, then pumped to the river under the dam.

When the reservoir is greater, Bernardo says, the quantity of water seeping by way of will increase as a result of the lake exerts extra stress.

A view of the 30-foot diameter penstock (bottom) from the penstock access room on the Arizona side, May 11, 2021, at Hoover Dam, on the Arizona/Nevada border.

A view of the 30-foot diameter penstock (backside) from the penstock entry room on the Arizona facet, May 11, 2021, at Hoover Dam, on the Arizona/Nevada border.
Mark Henle/The Republic

At the tip of the passage, we step right into a room with home windows that look out over the diversion tunnel and the penstock, a metal pipe 30 ft in diameter. Referring to a diagram on the wall, Bernardo explains how water enters the dam, spins the generators and discharges into the river.

If the water had been to say no about 125 ft from the place it stands, under the elevation of 950 ft, he says, Hoover Dam would lose the power to generate energy.

“That’s what we call minimum power pool,” Bernardo says.

If Mead continues to fall additional, the dam may nonetheless launch water right down to a stage of 895 ft.

“At 895 and below, Hoover Dam is unable to pass water by any conventional means. So you would essentially have to pump it out of Lake Mead. That’s what we call dead pool,” Bernardo says. “And at dead pool, Lake Mead still has 2.5 million acre-feet in storage, but there’s just no way to get it out.”

If the lake declines that a lot, solely the Southern Nevada Water Authority, which provides Las Vegas, has an intake deep enough to proceed pumping water.  

The dangers of Mead falling to such lows gave impetus to the final spherical of negotiations, which led to the 2019 signing of the Drought Contingency Plan at Hoover Dam.

The river would have been in a scarcity already years in the past if the states and Mexico hadn’t made concerted efforts to prop up Lake Mead’s levels, Bernardo says, and people steps included varied conservation packages which have yielded 4 million acre-feet over the previous 15 years, representing about 50 ft of water in the lake.    

But with the unrelenting dry years, he says, “we knew that we couldn’t postpone a shortage forever.”

Mike Bernardo, of the federal Bureau of Reclamation, on the ramp at Hoover Dam on May 11, 2021.

Mike Bernardo, of the federal Bureau of Reclamation, on the ramp at Hoover Dam on May 11, 2021.
Mark Henle/The Republic

He reiterates that the scarcity measures, together with the obligatory cutbacks, had been adopted to scale back dangers.

“And although it’s scary that this will be the first time we’re using them, they were designed by very smart people throughout the Colorado River Basin,” Bernardo says. “And let’s hope that they work the way that they were designed to work.”

If the state of affairs continues to worsen, he says, everybody concerned in managing the river’s water will get collectively once more, as stipulated in the 2019 agreements, to take steps to guard the reservoirs. With about 40 million folks counting on water from the Colorado and its tributaries, he says, “all of us as water managers have a responsibility to all of those that are in the basin.”

Stepping out of the ability home, we flip a nook and search for. Bernardo says it’s his favourite a part of the tour.

The sloping face of the dam towers overhead. Below is the blue-green river. Swallows glide and swoop over the churning water.

After taking pictures, we stroll to the bottom of the dam, the place a white stripe is painted on the platform marking the Arizona-Nevada line.

Putting a hand on the concrete, I really feel the vibrations of the dam’s generators whirring.

By mid-June, Lake Mead is ready to say no to its lowest levels on file. Hoover Dam will quickly maintain the smallest quantity of water because it was stuffed in the Nineteen Thirties. The subsequent few years might present how a lot water use must lower to rebalance the river and scale back the danger that Hoover Dam may someday fall silent.

Ian James covers water, local weather change and the setting for The Arizona Republic. Send him story ideas, feedback and questions at [email protected] and observe him on Twitter at @ByIanJames.

Environmental protection on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting group at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.


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