From The New York Times (Abrahm Lustgarten):
Could the end be near for one of the West’s biggest dams?
When Glen Canyon Dam was built in the middle of the last century, giant dam projects promised to elevate the American West above its greatest handicap — a perennial shortage of water. These monolithic wonders of engineering would bring wild rivers to heel, produce cheap, clean power and stockpile water necessary to grow a thriving economy in the desert. And because they were often remotely located, they were rarely questioned.
But today, there are signs that the promise of this great dam and others has run its course.
Climate change is fundamentally altering the environment, making the West hotter and drier. There is less water to store, and few remaining good sites for new dams.
Many of the West’s big dams, meanwhile, have proved far less efficient and effective than their champions had hoped. They have altered ecosystems and disrupted fisheries. They have left taxpayers saddled with debt.
And in what is perhaps the most egregious failure for a system intended to conserve water, many of them lose hundreds of billions of gallons of precious water each year to evaporation and, sometimes, to leakage underground. These losses increasingly undercut the longstanding benefits of damming big rivers like the Colorado, and may now be making the West’s water crisis worse.
In no place is this lesson more acute than at Glen Canyon.
And yet even as these consequences come into focus, four states on the Colorado River are developing plans to build new dams and river diversions in an effort to seize a larger share of dwindling water supplies for themselves before that water flows downstream.
The projects, coupled with perhaps the most severe water shortages the region has ever seen, have reignited a debate about whether 20th-century solutions can address the challenges of a 21st-century drought, with a growing chorus of prominent former officials saying the plans fly in the face of a new climate reality.
“The Colorado River system is changing rapidly,” said Daniel Beard, a former commissioner of the federal Bureau of Reclamation, which oversees the government’s dams in the West. “We have a responsibility to reassess the fundamental precepts of how we have managed the river.”
That reassessment, Mr. Beard and others said, demands that even as new projects are debated, it is time to decommission one of the grandest dams of them all, Glen Canyon…
It took 17 years for the reservoir to fill; 19 years later, a steady decline began. Thanks to the steady overuse of the Colorado River system — which provides water to one in eight Americans and supports one-seventh of the nation’s crops — Lake Powell has been drained to less than half of its capacity as less water flows into it than is taken out.
That relative puddle is no longer capable of generating the amount of power the dam’s builders originally planned, and so the power has become more expensive for the government to deliver, with the burden increasingly falling on the nation’s taxpayers. In 2014 the agency managing power at the dam spent $62 million buying extra power on the open market to make up for shortfalls. The dam’s power sales are relied on to pay for the operations of other, smaller, dams and reservoirs used for irrigation in the West, and as Glen Canyon crumbles financially, so might the system that depends on it.
But it is not just the reservoir’s overuse that is causing it to shrink. More than 160 billion gallons of water evaporate off Lake Powell’s surface every year, enough to lower the reservoir by four inches each month. Another 120 billion gallons are believed to leak out of the bottom of the canyon each year into fissures in the earth — a loss that if tallied up over the life of the dam amounts to more than a year’s flow of the entire Colorado River.
In all, these debits amount to “the largest loss of water on the Colorado River,” Mr. Beard said, enough to supply some nine million people each year.
Glen Canyon is not the only dam to fall out of favor. Other major projects are also being decommissioned or re-evaluated.
The Hoover Dam’s Lake Mead, which on Wednesday fell to its lowest level ever, some 145 feet below capacity, also loses hundreds of billions of gallons to evaporation and is now 37 percent full. The lake behind Arizona’s Coolidge Dam, one of the state’s largest reservoirs, is virtually empty.
…on the Colorado, water managers dispute the notion that it’s time for a change.
Glen Canyon Dam may be past its prime, said Michael Conner, the deputy interior secretary and a former commissioner of reclamation, but it’s not past its usefulness. Though he called the amount of water lost to evaporation and leakage “incredibly significant,” Mr. Conner credited Glen Canyon with numbing the pain of the recent drought. “Look at the last 15 years,” he said. “It’s the lowest inflow in history and there’s been no shortages on the Colorado River, and that’s because of Glen Canyon Dam and Lake Powell and Hoover Dam and Lake Mead.”
There is also a political tide to be reckoned with: the delicate peace accord struck among seven Western states in 1922, and later with Mexico, that divides Colorado River water among them, and the fear that they’d never be able to reach such an agreement again. Lake Powell is the gateway that gives the Colorado’s upper basin states control of their water, and a way to withhold every drop not required to be sent to the states downriver. Get rid of Powell, its protectors warn, and the states will drag one another into legal chaos.
But decommissioning Glen Canyon Dam could offer a solution hard to ignore — a cheap, immediate and significant new source of water where it is most desperately needed.
The idea is this: Since two of the nation’s largest reservoirs — Lake Mead and Lake Powell, just 300 miles apart — depend on the same dwindling water source but are each less than half full, they should be combined into one. Lake Mead would be deeper, and its evaporative losses would increase. But the surface area of Lake Powell would be substantially reduced, and the evaporating water from there would be saved. Furthermore, sendng the water out of Glen Canyon would move it from a valley that leaks like a sieve into one that is watertight. Evaporation losses at Mead — say plan proponents — would be more than offset by savings at Lake Powell.
In all, according to Tom Myers, a hydrologist who studied the proposal for the Glen Canyon Institute, an environmental group advocating for combining the two reservoirs, about 179 billion gallons of water would be saved each year — more than enough to supply the population of the city of Los Angeles.
The argument has weight because both reservoirs have been struggling to remain half full, and may never refill as temperatures rise because of climate change. At the same time, the Bureau of Reclamation predicts that demand for water will continue to increase on the river so much that by 2060 the region will run short by a trillion gallons each year.
The Glen Canyon Dam itself would not be removed. Rather, its gates would be opened, and the water behind it allowed to pass through, restoring the natural flows into the Grand Canyon just below it, draining Lake Powell, and allowing the magnificently scenic landscape of Glen Canyon to be resurrected.
The water would not be lost. It would simply flow down through the Grand Canyon and be recaptured behind the Hoover Dam in Lake Mead.
“To me it is a no-brainer,” said David Wegner, who studied Glen Canyon as a scientist with the Department of Interior. “You’ve got very few options.”
Vast tracts of land now submerged would be restored, and broad sections of river pinned between vertical canyon walls would be transformed into remote wilderness valleys, their floors once again inviting exploration on horseback or on foot. Dozens of archaeological sites, their walls covered in petroglyphs, would be revealed. The flow of the river through the Grand Canyon would again be defined mainly by the precipitation gathered by the mountains upstream.
Restoring Glen Canyon this way has long been the campaign of ardent environmentalists. Mr. Brower, who agreed to the dam’s construction without having ever visited Glen Canyon, mounted an intense campaign to save “the place no one knew” after seeing it. He called the reservoir his greatest regret, and the Glen Canyon dam has been a potent symbol of the desecration of wild places ever since.
Now the shortages on the river, and the likelihood that climate change is certain to make them worse, have breathed new, pragmatic life into their arguments.
Whether the “Fill Mead First” proposal would improve the water supply depends on whether Mr. Myers is right about the amount of water that leaks out of the bottom of Lake Powell. He puts that number at about 124 billion gallons each year. But the Bureau of Reclamation has not adopted Mr. Myers’s findings and has long said that water that seeps into the ground eventually returns to the river. Combining the reservoirs would save negligible amounts of water, in the bureau’s view.
“This is an attempt to find a water supply rationale which supports their recreational focus and narrow view of what the river should look like,” said Colby Pellegrino, the Colorado River programs manager for the Southern Nevada Water Authority.
Ultimately, the decision to drain Lake Powell — or perhaps to forgo the other new dam and water projects now in the works on the river — comes down to a question of whether the seven states and Mexico that share the Colorado River really need the water badly enough.
If they conclude that they do, abandoning parochial concerns about how the river is supposed to work, and changing the status quo, however uncomfortable or complicated, will begin to seem worth it.
But Jim Lockhead, chief executive of Denver’s water utility, said decommissioning the dam would probably require an act of Congress, a new agreement among seven state legislatures, a revised treaty with Mexico, and a lengthy federal environmental impact analysis.
“A half a million acre feet sounds like a lot of water,” he said, referring to the water saved by combining the Powell and Mead reservoirs, “but I don’t think it’s significant enough, frankly, to justify going through all of that.”