In 1963, the Glen Canyon Dam was built. It created Lake Powell Reservoir, which straddles Utah and Arizona, to ensure a water supply for the lower Colorado River basin states and Mexico. Over the past six decades, it has also become a recreation destination for millions.
The dam has experienced its fair share of unexpected trauma, threatening river flow levels, depleting water storage and exposing sediment.
Sediment is the walled molded mud that contains the Colorado River. It’s always been there, but historic droughts like those in 2002 and 2020 have caused the lifeline of the West to drop to alarming levels, exposing the mud.
Before the water is potable, it’s brown and murky.
“The Colorado got its name from the color. Colorado means colored red in Spanish. That red color comes from suspended sediment floating down,” according to Davide Ippolito, Returning Rapids researcher and the OARS river guide on our trip.
“I spend a lot of my days here just convincing people that this river isn’t just water. A lot of material is being transported. So when you have a lake at the bottom of that, the water stops moving, and that material, that sediment, just sinks to the bottom. And now we’re seeing, with the drought, all this exposed sediment that’s sunk to the bottom.”
Why should we care? Because the mud is being trapped above the dam, depriving the river below, and suffocating it above.
Mike DeHoff, Returning Rapids principal investigator, Susannah Erwin, National Park Service Water Resources Division river program lead, and Paul Grams, USGS Southwest Biological Science Center research hydrologist, talk about changes along the Colorado River by Gypsum Canyon rapid in Cataract Canyon on Saturday, Sept. 21, 2024. | Kristin Murphy, Deseret News
Shrinking storage and rising sediment levels
The silt buildup has decreased Lake Powell’s storage capacity by almost 7% since it was first created. “On average, the equivalent of 30,000 dump truck loads of sediment are deposited into Lake Powell daily. This is approximately 100 million tons annually,” per the Glen Canyon Institute, with most of the load coming from the Colorado and San Juan rivers.
While some sediment is natural and even beneficial for habitats and forming riverbeds and beaches, an excessive amount can lead to myriad environmental issues that harm the river’s health.
Mike DeHoff, principal investigator for the nonprofit Returning Rapids Project and lifetime river guide on the Colorado, recalled his experience boating down the river during the drought in 2002 and 2003.
“In Cataract Canyon, there are places where it felt like you were boating in this giant mud canal of ooze going down to the lower part of Cataract,” he said. “There are places where you couldn’t get out of your boat. It wasn’t safe,” emphasizing that he pulled people out of the mud that went in chest deep.
“That’s when many of us were like, what’s happening here? ... That’s when we started to see remobilization of all the stuff that was starting to be exposed.”
In the original Colorado River Compact of 1922, the seven basin states agreed to “remove causes of present and future controversies.” Sediment is not mentioned once in the compact.
More than 100 years later, and after the construction of multiple dams, it seems the issues caused by sediment were not anticipated by the original signers. Yet, on a six-day river rafting trip down the Colorado River, I witnessed firsthand masses of sediment falling from the banks into the river on multiple occasions.
On Friday, the National Parks Service published a press release reporting that “300-350 meters of shoreline slid from the river-left bank into the river channel,” creating a small rapid in the river’s main channel.
Mud deposits, referred to as mudbergs by Returning Rapids researchers, are pictured in the Colorado River and lining the river banks by Mille Crag Bend, between Cataract Canyon Glen Canyon Dam, on Sunday, Sept. 22, 2024. The sediment filled in when this area was submerged under Lake Powell. After the lake receded, mud remains. | Kristin Murphy, Deseret News
At what point does Lake Powell become a mud reservoir?
All dams have a lifespan, which is ended by structural aging, sediment build-up or other natural causes. The longer the issue goes unmanaged, the more expensive it is to fix. Without a sediment management plan, Lake Powell will cease to exist.
If nothing is done regarding the sediment flowing into Lake Powell, it will take approximately 750 years to be considered a mud lake. Though that might not sound imminent, it would likely lose its value as a reservoir much sooner than that.
Scientists, lawyers, river guides, even librarians and welders have devoted their careers to managing this issue, each with different insights into the best solution.
Dam reconstruction
Newer dam systems, like the Three Gorges Dam in China, are built with sluice gates that release sediment from the dam’s base. However, the only way for the system to operate is to drain the reservoir to get the momentum to carry the sediment out of the reservoir, Paul Grams, a research hydrologist at the USGS’ Grand Canyon Monitoring and Research Center, explained.
“Rivers carry sediment. Lakes collect sediment,” Grams said. “So the only way to carry sediment through is to turn it into a river. And you could do that artificially with a pump and a pipe, or you can do it by redesigning the dam to do it that way.”
While adding sluice gates to the Glen Canyon dam could theoretically move some sediment downstream, most experts agree that the costs, potential environmental impacts and the engineering nightmare alone make it too complex of a solution that wouldn’t lead to a long-term fix.
Jack Schmidt, USU’s Janet Quinney Lawson Colorado River Studies chair and Center for Colorado River Studies director, and Meg Flynn, Returning Rapids researcher, climb partially up a 40- to 60-foot high wall of sediment buildup called the Dominy Formation during a Returning Rapids trip in Cataract Canyon on the Colorado River on Friday, Sept. 20, 2024. It is named after Floyd Dominy, commissioner of the U.S. Bureau of Reclamation in 1963, who was responsible for the dam and Lake Powell. When asked about the future effects of sediment on the Colorado River, Floyd replied, “We will let people worry about it in the future.” | Kristin Murphy, Deseret News
Targeted dredging
“In the early 1900s, the river went in all different directions because of all of the sediment that was pouring into it, and the channel was jumping and going from place to place,” Jack Schmidt, program director for the Center for Colorado River Studies at Utah State University, told me. Now, “it’s jammed into a tiny place.”
Lake Powell is not regularly dredged like a harbor or smaller reservoir would be, but dredging occurs occasionally and is typically done to clear channels or maintain access for boat ramps and marinas, especially when water levels drop due to drought or lower inflows.
The National Park Service and other agencies have considered dredging projects to keep certain areas accessible. Still, these efforts are typically on an as-needed basis rather than part of a regular dredging schedule.
DeHoff and his team at Returning Rapids believe one way the sediment should be dredged is for its nutrient makeup so it can be purposed for aggregation by farmers in the local area, or it could be done using targeted sediment removal in specific areas where it hinders the reemergence of rapids and affects river flow.
Although the sand could be used as a resource if dredged, its size and location make some experts think that exporting it out of the river would be impractical and costly.
“It’s helpful to think about what it was — very productive — until we built these dams, and now it’s become unproductive,” John Berggren said. He’s the regional policy manager with Western Resource Advocates.
Both Schmidt and Berggren are unsure what the proper course of action is now that the silt remains blocked from moving through the lower basin, where areas like the Grand Canyon are starved of sediment. Beaches where the Colorado used to meet the sea are eroding because sand that should reach the coast is instead trapped in reservoirs like Lake Powell and Lake Mead.
“You can’t move this with a truck down to somewhere to grow food. But historically, it’s incredibly productive,” Berggren added. Still, “the only way to make this economical would be moving it via river. And we have too many dams to do that.”
Eric Balken, Glen Canyon Institute executive director, gives a talk in Clearwater Canyon during a Returning Rapids trip through Cataract Canyon on the Colorado River on Saturday, Sept. 21, 2024. Where the group is standing would have been under 20-30 feet of water when Lake Powell was at its highest, estimates Mike DeHoff, Returning Rapids principal investigator. | Kristin Murphy, Deseret News
Removing the dam completely
Perhaps as controversial as the creation of the dam itself is the proposal to remove it.
After the dam was completed, the sediment became “confined in a levee,” Schmidt said. “And everything beyond the levee is massive farm fields” where sediment would benefit agriculture.
Eric Balken, the executive director of Glen Canyon Institute, a nonprofit focused on restoring the Colorado River through Glen Canyon, said that people need to have a future outlook on what keeping the dam in place will look like.
“What does this river system look like in 20 or 30 years? Does it make sense to try to operate these two massive reservoirs that are mostly empty, or does it make sense to consolidate?”
To some conservationists, including Balken, the Glen Canyon Dam should be deconstructed, the water stored solely in Lake Mead, and Glen Canyon should be established as a national park.
“Will Lake Powell ever be drained? It’s mostly drained now,” Balken said. “As the reservoir goes away, what comes out of the water is similar to those parks and monuments that we really value as a society; we’ve chosen to protect those places. And so I think Glen Canyon, which is coming out of the water deserves similar protection. I don’t think it makes sense to think of it as just a storage reservoir.”
However, not everyone shares the same sentiment. Colorado River Commissioner of Utah Gene Shawcroft told the Deseret News that even the removal of the dam would not restore the Colorado River to its former glory.
“There is no way, once you’ve been delivering water to 40 million people and to seven states and the Republic of Mexico, that you’re going to go back to a river that was what it was before men showed up. That’s just not in the cards,” he said. “There are always those who wish it could be turned back that way, but that’s impossible because of the economic system and the population that’s grown to depend on that water.”
“If all those dams were removed, would it be different? Sure, it would be different, but it couldn’t be like it was pre-1922 and still make available the benefits to 40 million people that depend on the river.”
