Humans Killed Cataract Canyon. It Brought Itself Back to Life

he river churns
a muddy brown as it carries us through towering vermilion rock walls toward the roar of Gypsum Canyon Rapid. The sound of water breaking over boulders grows louder as we approach, but Mike DeHoff shows no fear at the coming chaos. Rather, as he works the oars of his 18-foot raft, full of a week’s worth of camping gear and science equipment, it’s clear that he is, instead, thrilled. DeHoff is a local from Moab, Utah, and he’s rowed this stretch of the Colorado River, called Cataract Canyon in homage to its long series of vicious rapids, countless times. But he’s never rowed Gypsum before. 

That’s because until recently, this rapid wasn’t here. It’s only just fully resurfaced this month after being drowned for nearly half a century under the water of the Lake Powell reservoir.

Sixty years ago, this stretch of river was considered as ferocious — and nearly as beautiful — as the Grand Canyon. Then, in 1963, the Glen Canyon Dam was built to store water for human use, which backed up the Colorado River behind it to create Lake Powell. The rising waters snaked upstream, inundating the main river and dozens of its side canyons. Here, at its farthest reaches in Cataract Canyon, the reservoir flooded rapids and then buried the riverbed, including the boulders that made up those rapids, in thick layers of sediment — a mud plug that built up to be so enormous that it flattened out the steep gradient of the riverbed that had made those rapids so fierce. 

But miraculously, Cataract Canyon is reemerging. 

As the Southwest experiences its worst drought in 1,200 years and the mountains at the headwaters of the Colorado receive less snow, Lake Powell has been dropping, and below the dam, the Grand Canyon stretch of the Colorado is in crisis, sparking an increasingly urgent conversation around how to get water to the dry West in an age of climate change. But upstream is a quiet glimmer of hope that could influence how we manage this critically important river — and how we think long-term about water use, conservation, and the practicality of man-made climate solutions.

Here in Cataract, as Lake Powell slowly dries up, historic riverbanks and the river itself are resurfacing. The force of the newly free-flowing current is carving through and washing away the giant dam-deposited sediment plug as the Colorado restores and renaturalizes itself in the wake of receding reservoir waters. The result is an entire ecosystem coming back online right before our eyes, largely on its own, without human management. In the midst of climate-induced change, it’s a remarkable illustration that even after humans have walloped it, a landscape can recover. 

“The rate of change this year is unlike anything we’ve ever seen,” DeHoff says from his station on the oars as we glide through Cataract Canyon. The river, its banks, and its gradient are transforming so fast that boater informational guides can’t keep up with new beaches forming and old ones slumping away, temporary rapids created from mud moving downstream, and historic rapids resurrecting. 

Last night, at our camp upriver from the Gypsum Canyon Rapid section, DeHoff and two other Returning Rapids Project founders — his wife, Meg Flynn, a librarian; and professional river guide Pete Lefebvre — compared archival photos from before the dam was constructed with current images from a time-lapse camera they’d set up above the rapid site. They declared that Gypsum, which had been covered in flat water and buried in mud as recently as 2017, now appeared to be nearly fully returned to its former pre-dam power.

Without DeHoff, this environmental miracle may have gone entirely unnoticed on the national stage. 

DeHoff is in his early fifties and still sports a boyish smile. He’s perpetually in sandals, with wind-tousled hair, his hands cracked from water and rowing, the skin around his eyes pale against his cheeks in a sharp sunglass tan. He looks like a casual rafter — not the head of an increasingly influential organization. But he runs Returning Rapids, a small group of river-rafting enthusiasts who consider Cataract Canyon a second home. They’re the only ones coordinating researchers, conservationists, state- and federal-agency representatives, and storytellers to study and spotlight the river’s recovery — to hopefully, in turn, influence key decision-makers to prevent drowning it again in the name of seemingly insatiable human consumption.

Mike DeHoff, Meg Flynn, and Pete Lefebvre (from left) helped identify the returning rapids of Cataract Canyon.

We’re midway through the Returning Rapids annual fall science expedition along with researchers and others studying this changing landscape. As DeHoff expertly positions the big raft, Flynn rises to stand in the bow for a better view of the full force of Gypsum. The whole of the strong current appears to explode over a submerged boulder the size of a pickup truck and recirculate like a violent washing-machine cycle. Flynn would like to be on the oars herself for this, but has bestowed the honor of first run to DeHoff. She leans down to kiss him. And then the cold power of nature at work breaks over us.

OUR CULTURE KEEPS diligent track of dates when harm was done to the American people, Flynn says. “But there’s less awareness around moments when we perpetrated great harm on our landscape.” 

She’s thinking of March 13, 1963: the day the doors closed on the newly built Glen Canyon Dam to begin backing up the Colorado River. As the reservoir filled, an unknown number of plants and animals were killed, and countless cultural, sacred, historical, and recreational resources were sunk. Once known as the “Graveyard of the Colorado” for the boats of the early exploratory expeditions it dashed to pieces, Cataract’s nickname took on a new meaning of environmental grief.

Dams are a common feature on rivers throughout the world, built to store and provide water and hydroelectric power to people living downstream from them; there are 91,000 in the United States alone. The ones on the Colorado River, including Glen Canyon Dam and its reservoir, Lake Powell, are the largest. This mighty river provides water to nearly 40 million people in the West — from Los Angeles, Las Vegas, Phoenix, Denver, and Salt Lake City to myriad small towns in between — and irrigates 5.5 million acres of agricultural lands, including the Coachella and Imperial valleys, which grow and raise food eaten all over the country. 

To understand the dam requires knowing the impossible demand on the Colorado River. Back in 1922, officials from the seven states the river runs through met to decide how to divide up and use its water, and codified the resulting agreement in the Colorado River Compact. The compact, though, had a serious complication built into it from the start: It allocated around 16 million acre-feet of water among the states for use even though only 12 to 13 million actually flow through the basin. (For perspective, one acre-foot is equal to 326,000 gallons, enough to flood a football field one foot deep.)

“It was a conspiracy of plenty,” explains Michael Fiebig, Southwest River Protection director for American Rivers. Fiebig was one of Returning Rapids’ first conservation allies, and, an experienced rower, he’s guiding one of the rafts on this research trip. “The theory was that you couldn’t have gotten the seven states to sign a compact if it was going to short some of them.”

A guide takes on the rapids which have been buried under sediment for decades.

Len Necefer

But the Colorado’s flow was inconsistent, fiercely fickle between torrential floods and trickles. Thus Glen Canyon Dam was built to create Lake Powell as a storage shed, a sort of “bank account” to make withdrawals from to constantly deliver promised water — and the decades of over-allocation built into the compact, on top of drought, means we’ve been pulling water from the Colorado faster than the reservoirs can refill. “And now,” Fiebig says, “in a changing climate where we’re supposed to get up to 50 percent less water by 2100, you can see why there’s a problem.”

New rules for how the river’s water is managed and shared are being developed to address that problem for the next quarter century. “What we do on the Colorado is being watched worldwide,” Fiebig says. “It’s one of the most managed rivers in the world, that supports a massive economy. And it’s a bellwether for how highly managed, highly climate-susceptible rivers are going to deal with over-allocation and persistent drought.” 

The rulemaking is a ridiculously complicated process with a dizzying array of stakeholders. And, like the 1922 negotiations, it’s “hugely political,” says Amy Haas, executive director of the Colorado River Authority of Utah, which works on that state’s water interests on the Colorado. It’s not as simple as pitting river restoration against irrigating fields and providing drinking water. Rather, it’s about all seven states accepting the fact that they have to change the way they do things by making significant adjustments due to the overall decreasing water supply. “Everyone’s going to have to share in the pain,” Haas says.

Across the West, the implementation of large- and small-scale solutions could greatly reduce the demand on the Colorado, from replacing lawns with native plants to updating antiquated water-rights laws to transforming the industrial agriculture that consumes the bulk of the river’s water. But changing social attitudes, policies, and entire industries when it comes to something as vital as water is exceedingly difficult and complicated. Which is why, Fiebig says, some stakeholders still seem focused on continuing to plumb the water for all it’s worth — a repeat of the 1922 politics that contributed to landing us in a water crisis in the first place. “But for us in the conservation world and our partners in the tribal world,” he says, “the big question is: Is there room for the river itself?”

This era of climate change has largely been one of realizing irreparable loss of species, habitats, and resources, and what many would call frustratingly slow responses where politics trump environmental realities. Rarely have we seen such a clear example of nature healing itself from our destruction of it — and been presented a second chance, on such a large scale, to make a different decision about our collective future.  

DeHoff sits next to me on a beach with the morning just blushing the cliffs, drinking coffee. “What’s special about where we are now,” he says, “is that this is the last wild stretch of the Colorado before we kill it.”

He takes a moment to collect himself; the fact that the Colorado is so used up that it no longer touches the sea overwhelms him. He isn’t after some radical goal like dismantling the dam tomorrow. But he thinks decision-makers need to acknowledge that we’re using more water from this basin than actually exists, more than we even need. “I just call bullshit. We’re enslaving environmental forces. We’re making the Colorado River participate in The Giving Tree,” he says, referencing the story of a boy who takes all the resources from a tree and then, as an old man, sits down on the only part remaining: a dead stump.

THE FIRST TIME DeHoff saw this canyon was in the early 1990s. He was 21 and a new river guide. Camped above the start of the famously fearsome rapids, he woke before dawn in a fit of anxious energy, packed his boat by moonlight, then fell asleep under a pile of life jackets to keep warm. No one could find him in the morning until a guest sat on the pile. Those were the days when the rapids, reduced to just 14 churning miles from their historic 41, ended below a thunderous falls called Big Drop 3.

Now, DeHoff is 52. He switched to welding after river guiding, but never stopped running rivers. He sold his welding business just a few days before this trip to run Returning Rapids full time, even though there are no funds to pay himself with yet. 

He would sooner sink his own raft than brag, so I hear about his river expertise elsewhere. Lefebvre says DeHoff has run Cataract’s rapids at terrifyingly high river flows that most people won’t touch. Flynn says the two of them once navigated a stretch of this river by lightning strike to escape a flash flood. DeHoff himself stopped counting his trips down Cataract at one hundred, a long time ago. So when things started to change, he noticed. 

In 2012, Lake Powell levels started receding noticeably, and Cataract Canyon, at the far edges of the reservoir, was the first to begin resurfacing from under the ebbing lake waters. Moving water then uncovered the built-up sediment.

In 2013, DeHoff began keeping a spreadsheet recording shifts as the reservoir dropped — mostly observations on shoreline change and where currents had begun flowing again — to share with the national-park rangers he ran into on his trips down Cataract. In 2014, Lefebvre, also a Moab local, started coming by DeHoff’s welding shop to compare notes on evidence of rapids beginning to return below Big Drop 3. Flynn, then finishing her master’s degree in library science, searched obscure archives for old pre-dam photos of the river to cross-reference which rapids the returning ones might be, and to what extent they were resurfacing. Soon, Chris Benson, a Moab geologist turned pilot, also joined to offer aerial reports of water and riverbank changes. DeHoff likens this inception of Returning Rapids to a bad joke: “A librarian, a river guide, a pilot, and a welder walk into a bar and ask, ‘When’s the next rapid coming back?’”

Thanks to the changing waters, Returning Rapids has also identified cultural markings that have reappeared.

Len Necefer

Today, the reservoir has receded so much that Cataract’s side canyon of Clearwater has resurfaced as a calm oasis of native willow and primrose; Dark Canyon has returned to its pre-dam state as a gentle creek with a reputation for swinging like a merry psychopath to catastrophic flash floods. In all, 10 historic rapids have reemerged. 

Since Returning Rapids ran its first science trip down Cataract Canyon in 2019, with the U.S. Geological Survey (USGS) and university scientists who’d been connected to the project by various people in the river community, this place has repeatedly blown researchers’ minds with a scene that, as recently as 10 years ago, few people thought was possible, given the scale of Glen Canyon Dam’s impact. But thanks to those trips, resurfacing cultural and archaeological resources have been found and documented, including ancient rock art and inscriptions from early boating expeditions. The USGS has installed gauges where none have existed for decades to measure the flowing river. Geologists and hydrologists have conducted groundbreaking studies of how sediment moves in and affects a drought-impacted environment, and of methane seeps and volcanoes (organic matter breaking down in exposed reservoir sediment releases methane and other gases in the air that impact the carbon cycle). Many of these are the only studies of their kind: cutting-edge science that will be the foundation of research as reservoirs are drawn down in drought-affected regions around the world. 

“I cannot emphasize how amazing, and important, it is that Returning Rapids is convening the science community around this, and bringing in agencies and tribal communities and people from different backgrounds,” says Brenda Bowen, a geoscientist with the University of Utah who’s been coming on Returning Rapids trips since 2019. “It’s already changed the trajectory of the outcomes of this landscape because they’ve brought more attention to it, and they’re helping people organize around it.”

And yet many river rafters, conservationists, and scientists see these lower reaches of Cataract Canyon, for all of their scientific, cultural, and recreational significance, as falling through the cracks of government-agency management, where no precedent seems to exist for who takes responsibility for a reservoir turned returning river. Eric Balken, executive director of the Glen Canyon Institute, which focuses on restoring the Glen and Grand canyons, says that “many land and water managers treat the emerging landscape as an area that will one day be under water again, even though the data suggests the opposite. This management approach of ‘That’s just where the reservoir used to be, it’s not important’ is so misguided. As the reservoir comes down, what’s emerging has similar qualities to all the popular and cherished parks and monuments in this area, like Bears Ears, Grand Staircase Escalante, and Grand Canyon.” 

A recent environmental impact report by the Bureau of Reclamation, which is in charge of dams, implied erroneously that mostly invasive species were returning as Lake Powell’s water level dropped. But Returning Rapids has brought scientists down Cataract, who find native plants returning, birds returning as shorelines emerge, beavers returning as willows and cottonwoods sprout on those shorelines. In response to a request for comment, the Bureau of Reclamation directed me back to the report with the erroneous implications. 

Canyonlands National Park, which manages the river, and Glen Canyon National Recreation Area (NRA), which manages the reservoir, tell me in a joint statement that the agencies are aware of the landscape emerging in Cataract; staff see it on routine river patrols and receive Returning Rapids’ trip reports. Both agencies “maintain active programs for resource monitoring throughout the park, including monitoring of archaeological sites, monitoring for invasive vegetation species, and monitoring of various plants and wildlife species. As the lake level drops, areas of shoreline are incorporated into the park’s existing science-based monitoring and research programs to understand and respond to the changing lake environment.”

Returning Rapids regularly shares its observations and data collected from scientists on its trips with these and other agency managers, and has invited and brought Canyonlands officials on its science expeditions. DeHoff has also invited officials from the NRA, but none have yet accepted. Although Returning Rapids recently attained a new degree of credibility in becoming a project under the Glen Canyon Institute, often when DeHoff shares real-time data of changing conditions with agency decision-makers, he says, he’s usually greeted with some iteration of “Wait, who are you guys?” 

The Returning Rapids crew — it’s hard to call them “staff” when they volunteer their time and even all of their own river equipment to run research trips — aren’t scientists, conservation experts, government employees, or lobbyists. They’re average people who care deeply about a particular place and have the specialized river skills to bring scientists and policy-makers to see it. But DeHoff isn’t afraid to push for meetings with high-level government staff, nor to ask agency bigwigs what their plan is for managing all of the backed-up mud on the emerging river — the response to which, he says, in the early years of sharing his observations, was generally “What mud?”

THE MUD FIRST becomes apparent as we start running the resurrected rapids. Lefebvre points it out as we float by masses of the stuff spiked from the river like dirt icebergs, creating roiling hydraulics in the current. Miniature mountain ranges of mud line the shore. Soon it towers two stories high on either side of the river: remnants of the great sediment plug, courtesy of Glen Canyon Dam, that the Colorado is tunneling through to restore itself.

Bowen explains that a natural river carries sediment downstream, depositing it here and there to create wetlands for birds and insects, habitat for fish, soil for native plants and trees, sand for beaches. The Colorado is milkshake-thick with it. But as the river slows down coming into Lake Powell, it drops its sediment, and then the dam stops that sediment from moving downstream, starving ecosystems from the Grand Canyon to the Mexican delta of their wetlands, sand, and soil. It’s estimated that Lake Powell has lost 6.8 percent of its storage capacity due to sediment buildup. Bowen calls it a reminder that we didn’t just flood Glen and Cataract and all of their natural and cultural resources: “We buried them, too, and that’s another level of heartbreak.”

After we run Gypsum rapid, DeHoff attaches a motor to the raft to cover miles of flat river, where the historic rapids are still buried under 40 feet of sediment. We’re headed to the particular mud feature that’s the main attraction of this science expedition. It’s called a slump, where sediment layers collapse onto emerging riverbank or into the river. And this one is spectacular: so big that it could be seen on satellite imagery, the moment an enormous section of sediment collapsed last July, dumping its terraces to create new waves and shoving the biggest river in the West into a tight 20-foot channel. Returning Rapids named it the Space Slump. It’s the largest single movement of sediment that the group has observed yet.

Suddenly, an acrid odor of sulfur burns our noses. Then we round the river bend and see it: A human-caused landmass bigger than a Super Walmart has collapsed into the river. Dried sediment blows off it like moon dust. Great islands of mud that broke from the slump upon impact jut from the channel. DeHoff ties up to a solid piece of shore rock across from the slump. Bowen gives a safety talk about walking on the formation. Dried sediment can collapse without warning, creating avalanches of earth that can easily bury a person. Wet sediment is so unconsolidated that unsuspecting people have sunk to their chests in it. As it dries, it creates dangerous crevasses that can also swallow a person.

Bowen had told me her fieldwork often consists of staring closely at a single sediment wall for several hours. It’s immediately clear this is not what will happen here, that to measure the Space Slump presents an overwhelming, perhaps impossible, task. The slump wall is moated in a fast current with dangerous eddies that can suck down the side of a boat, there’s a gargantuan amount of mass to be surveyed, and where the hell is the sulfur smell coming from? Everyone looks to DeHoff, who begins to direct operations like a symphony conductor.

This moving sediment is so large it can be viewed from space.

Len Necefer

 What ensues is a high-adrenaline display of adventure science, requiring significant boating skills and the human power of nearly every person on the expedition. Lefebvre and geologist Gary Gianniny scramble 200 feet up to a ledge to photograph the slump from above. Bowen, after realizing that the $50,000 GPS unit can’t reach enough satellites from the safety of the shore to perform its high-detail mapping, instead sets it up on a deteriorating mud island with another professor to babysit it. She takes the other precision GPS unit (also expensive) and dangles it from a pole midair above the water as one of the boaters motors upriver through hazardous hydraulics in order to map the perimeter of the slump. The batteries on both devices are running out as quickly as the daylight. 

DeHoff guides another contingent, that includes Fiebig and Flynn, across the river to hike up collapsing sediment to survey the top of the towering slump. One person loses their footing and falls hip-deep into a crevasse (a lucky stop, as the dark chasm appears to extend much farther down), but it’s worth it for what they find.

Old records tell of a hot spring that used to be here, but no one’s seen it for 50 years. Now it’s reemerged to create a lake on top of the Space Slump. Bowen believes this change in landscape is what caused the great mass to collapse in July: In concert with the river eroding from one side, spring water weakened it from the other. The spring will eventually weigh the lake with so much water that it will collapse the sediment entirely, and the river will take it from there. Eventually this particular stretch will be fully scoured of backed-up sediment as the Colorado River rushes back to its natural state.  

Which presents the inevitable question: If the river is this capable of restoring itself after being drowned, why not just keep refilling Lake Powell when we can during high-water years to mitigate climate-induced drought? Why couldn’t it keep fixing itself again and again?

“Because of extinction,” riparian ecologist Cynthia Dott says succinctly. There’s no guarantee that the native plants and animals recolonizing the banks during this first resurfacing will survive a second drowning, let alone repeated drainings and drownings. “Once a species’ habitat is so destroyed by human activities that it can’t survive anymore, it’s gone forever,” Dott adds.

WE’VE FLOATED OUT of Cataract Canyon into the current reservoir boundary; gone is the sound of rushing river, and the water’s color has changed from brick to pale green as sediment drops out. This is where the river dies — it’s an emotional place for DeHoff and Flynn. They pull the raft up to a soupy mud bank. This spot was 50 feet underwater earlier this summer as the reservoir refilled after a wet spring, flooding landscapes that had come up for air over the past few years. It had drained as the reservoir dropped, and was drowned again to refill Lake Powell. 

“It was river as far as the eye could see here last year,” DeHoff says sadly.

We step up to a huge boulder. Carved on it is the looping inscription of a name: Powell. That is Major John Wesley Powell, from the first expedition of white people to map the remote reaches of the Colorado River, in 1869. The faded letters are difficult to see, eroded with repeated submersion. If we keep letting the reservoir drop and refill, this historic carving will go the way of the thousand-year-old fort a stone’s throw from here. 

When the reservoir receded in 2004 to reveal the site of the fort for the first time since Lake Powell filled, the square 25-foot-high stone structure had been reduced to a pile of rocks by the weight of water. Last year, when the site emerged again at low water, the ancient fort was gone completely. The Bureau of Reclamation recommends keeping drowned cultural and historic resources underwater as the best way to protect them from over-visitation, vandalism, and wave action. But it’s already too late for these disappearing pieces of the past at the shifting boundaries of the reservoir. 

“Returning Rapids does a lot of work to make sure this stretch where so few people come is seen,” Flynn says. Most people rafting Cataract Canyon take out upstream of here — including recreationists and agency staff — and few Lake Powell users make it as far as these upper reaches. “We have to be able to recognize and own the harm perpetrated,” she adds, “so that we as a culture or nation decide to make positive change.”

We motor on. The water turns a clear blue against red walls, an unnatural juxtaposition of desert landscape. We’re in the flooded reach of Glen Canyon. Here in what venerated nature writer Edward Abbey once called “a portion of Earth’s original paradise,” the water-stained walls are crumbling. Repeated inundation has weakened the sandstone, DeHoff explains, causing the rock to collapse in places. At a sheer cliff face known as the Tapestry Wall, DeHoff cuts the motor. He and Flynn climb out to stand on a sandstone ledge that, half a century ago, soared nearly 200 feet above the river. Reservoir water laps at their feet.

Cataract’s rebirth miles upstream from this spot, where the scale of the dam’s impact is still so apparent, keeps DeHoff and Flynn grounded in their mission. And it turns out that what’s happening in Cataract isn’t isolated. 

Side canyons all over Glen are restoring themselves as the reservoir drops. Much like a small group of river runners with the potential to help shift the course of this river’s future — and in turn catalyze a shift toward sustainability in the West’s politicized water wars — nature might yet hold some surprising power over the seemingly overwhelming forces of the Anthropocene.

As we motor away from the Tapestry Wall, Flynn gazes back at the ledge. “One day we’ll look up from the river and think, ‘Remember when we stood up there?’”