The Glen Canyon Dam controls the flow of water to the lower Colorado River. If the antiquated dam breaks down, the Upper Basin States break their promise to everyone downstream. Is it time to say dammit to the whole dam thing?
The Glen Canyon Dam needs a massive overhaul if it’s going to keep delivering hydroelectric power—or, for that matter, water to the lower Colorado River.
Amidst contentious negotiations to decide who gets how much after the Colorado River’s current water guidelines expire in 2026, a letter from the Lower Basin states to the U.S. Secretary of the Interior demanded that any decision-making include the necessary infrastructure repairs and improvements to ensure the river keeps flowing beyond Glen Canyon Dam.
“I think a lot of people, especially in Utah, don’t really realize that Glen Canyon Dam and Lake Powell were not built for recreation,” says Eric Balken, the Executive Director of the Glen Canyon Institute.
Millions of people in Arizona, California, Nevada and Mexico depend on water flowing through Glen Canyon Dam. Whether we like it or not, the Upper Basin states have a legal obligation to deliver water downstream to the Lower Basin.
“The dam was built to deliver water to Lake Mead in an exact amount…to fulfill an accounting obligation under the Colorado River Compact,” says Balken. But that “accounting system” is on the verge of crashing.
Shortsighted Dam Design
In the 1950s, when the engineers who built the Glen Canyon Dam designed its penstocks and outlet works, they must never have imagined the water levels of Lake Powell dropping below full. They certainly would not have imagined the “bathtub ring” we see now, high above the water’s surface. If they had, they might have had the insight to install a drain. They didn’t.
If the water level ever falls below the penstocks, which send water from the reservoir through the turbines and into the Colorado, the dam can no longer generate electric power. The penstocks, which were installed too high at hundreds of feet above the original river bed, have a failsafe…but it’s failing.
There are lower bypass tubes called “river outlet works” (ROWs) that allow water to continue to flow through to the river when the lake is lower, but a 2023 release damaged the ROWs. Pockets of air and sediment caused cavitation; shock waves that damaged the surface of the tubes. The U.S. Bureau of Reclamation, which manages the dam, repaired the ROWs’ surface lining but acknowledged that even relining the outlets “will not prevent the risk of additional cavitation” when the dam is operating at low reservoir levels.
The Lower Basin states’ letter shows that recent proposals maintain the levels of Lake Powell by releasing less water to the Lower Colorado, which risks the livelihoods of everyone downstream and does not contend with the dam’s potential crash.
But there are other options. Maybe the need for the dam has passed?
A big dam mistake?
“We’ve got these huge dams and not very much water behind them,” explains Balken. “These huge reservoirs are mostly empty.” In addition to upstream diversions, climate change has reduced water flows by as much as 20% and is projected to continue decreasing in the decades to come.
“You’ve got this impending engineering disaster at the dam. We don’t have enough water to fill either Powell or Mead. So, what we’re proposing is what we call ‘Fill Mead First,’” says Balken. The proposal advocates for studying what a full bypass of Glen Canyon Dam would look like.
“A lot of people consider Glen Canyon Dam to be one of our country’s greatest environmental mistakes,” says Balken. When it was commissioned in 1956, the National Environmental Policy Act (NEPA) and the Endangered Species Act did not yet exist. Now, we better understand the downstream effects of the dam on the Grand Canyon ecosystem, like endangering native fish species. Upstream, when the dam created Lake Powell, it flooded canyons; archaeological sites and native plants and animals disappeared under the water.
The canyon shows what it was like before the dam. “We’re seeing the return of cottonwood and willow forests and beaver and birds and all of this wildlife, and the emergence of cultural sites, waterfalls, grottoes, arches and bridges,” says Balken. “There’s a national park coming back to life in Glen Canyon right now because the reservoir is low. It’s shown us a glimpse of the potential for restoration in Glen Canyon.”
What is ‘Cavitation?’
The Glen Canyon Dam has had trouble with cavitation in the past. This phenomenon happens when water under extreme pressure forms, and then collapses, vapor-filled bubbles, generating shock waves. This nearly caused a catastrophic failure of the dam in 1983; the tunnel spillways were designed for short-term use, but a flood on the upper Colorado caused cavitation to set in. Emergency efforts narrowly averted a total failure, but cavitation remains a threat to the dam’s integrity.
How this effects Utah
As far as giving up Lake Powell, Balken says, “I can totally appreciate why people love the reservoir. I’m a Utah boy. I know plenty of people who love going to the reservoir to recreate. But it will transition from a reservoir destination to a river destination.” The Glen Canyon Institute believes Glen Canyon should be a national park that might look similar to parts of Canyonlands or the Grand Canyon.
But in this version of the future, Glen Canyon will not be free of all dams. Balken has made regular trips to Davis Gulch for 15 years, sometimes as many as five times a year. On his most recent trip, “The whole canyon was just full of beaver dams,” he says. “We probably saw eight or ten good-sized beaver dams in Davis Gulch. When the beavers come back and reclaim a canyon, that’s when I was like, okay, we’re back. This is a restoring canyon. Look, we made some mistakes with Glen Canyon Dam, but we don’t have to live with them.”
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