A waterfall could soon form on the Colorado River as Lake Powell drops

A potential barrier to rafters, would a waterfall benefit endangered fish? An existing waterfall on the San Juan River provides some hints.

(Zak Podmore | The Salt Lake Tribune) Crews with the Bureau of Reclamation and U.S. Fish and Wildlife Service net endangered fish below the Piute Farms Waterfall in southeast Utah on Tuesday, March 29, 2022.

Piute Farms Waterfall Each spring on the brushy banks of the San Juan River, a bucket brigade assembles twice daily.

Biological technicians with the U.S. Fish and Wildlife Service find their footing on wet riverside rocks and pass five-gallon buckets up the edge of an 18-foot waterfall near the Navajo Nation. The crews then carry the buckets a quarter-mile upstream by hand, following a path feral burros have forged through thickets of tamarisk in an area that Lake Powell once covered.

Inside the plastic buckets rides a precious, if somewhat disoriented cargo: endangered fish species preparing to spawn.

Over five days at the end of March, three technicians from Colorado managed to pull 61 endangered fish over the falls — mostly razorback sucker and a few Colorado pikeminnow, native species that can both live for 30 years. Other crews will staff the site in the coming weeks, and close to 200 endangered fish are expected to be transported in total.

(Zak Podmore | The Salt Lake Tribune) Matt Bogaard (left), a fish researcher with Kansas State University, and recently retired U.S. Fish and Wildlife regional program director Tom Chart attempt to net endangered fish below the Piute Farms Waterfall in southeast Utah on Tuesday, March 29, 2022.

It’s a cumbersome process, but Matt Bogaard, a researcher with Kansas State University who studies fisheries in the San Juan River basin, said it’s largely effective in helping the fish move upstream. Bogaard monitors the river corridor using scanning equipment and microchips that have been injected into the fish, technology similar to implanted pet tags.

Once the fish are around the falls — a barrier that’s too large for them to navigate without the bucket assist — the tracking data shows that 96% continue their journey. After they’ve spawned and the females have laid their eggs, many fish head back downstream and wash over the falls once again.

Origin of the Piute Farms Waterfall

As the native fish evolved over hundreds of thousands of years in the warm, muddy waters of the San Juan and Colorado rivers, they could move freely between the Grand Canyon in Arizona, Utah’s Glen Canyon, and the upper reaches of the San Juan River in New Mexico and Colorado.

But as Lake Powell filled to its capacity for the first time in the early 1980s, the San Juan’s historic channel became packed with sediment. When the reservoir level dropped again — first in the late 1980s and then in the year 2000 — the river cut a new path that was located more than half a mile from its original bed.

After the San Juan had scoured away the reservoir sediment, it started to run over bedrock and the waterfall formed, blocking fish passage.

The drop acts as a small dam, and it turned the upstream section of the San Juan — an area popular with recreational river runners — into a labyrinth of sandbars and silt that extends for over 20 miles, prompting some rafters to call for the removal of the waterfall. Returning the river to its original bed and restoring a fish passage would cost around $3 million, according to one recent estimate.

Bogaard said crews capture and move 20% to 25% of the razorback suckers that get trapped below the waterfall each year, meaning most fish don’t benefit from the bucket brigade. No razorback suckers have been known to reproduce in the river below the waterfall.

But perhaps counterintuitively, some fish researchers believe the waterfall has been beneficial to the endangered fish, which have struggled to survive in a river system substantially altered by dams, diversions and the introduction of nonnative species.

Although the waterfall blocks the migration routes of endangered species, it also prevents nonnative fish in Lake Powell — carp, walleye, striped and smallmouth bass, and others — from swimming into the San Juan and competing with native species.

Is a new waterfall forming on the Colorado River?

A similar fish barrier called Pearce Ferry Rapid — a surging Class V cataract — formed over a decade ago just downstream of the Grand Canyon after Lake Mead’s level dropped due to a decadeslong dry spell known as the Millennium Drought.

The process may be repeating itself on the Colorado River near Hite, where the river meanders through a wide basin of silt below an abandoned marina once frequented by houseboats on Lake Powell.

(Christopher Cherrington | The Salt Lake Tribune)

Last summer, the reservoir dropped to its lowest level since it first filled, and the decline has continued. Its elevation is currently 44 feet lower than a year ago, below a quarter of its capacity. The low reservoir levels have allowed the Colorado River to cut through the sediment, and as was the case with the Piute Farms Waterfall and the Pearce Ferry Rapid, the river abandoned its historic channel.

Researchers with the U.S. Geological Survey used sonar equipment to study the river last fall and determined a waterfall or rapid could begin to form in the near future just downstream from the North Wash boat ramp that serves as a takeout point for rafters who’ve run Cataract Canyon.

The pre-dam river bed is about 40 feet below the current channel and it’s downcutting quickly. While it’s difficult to say what the rapid will look like, there’s a good chance it will present an unrunnable obstacle for boaters — and a barrier for fish.

(Francisco Kjolseth | The Salt Lake Tribune) Bob Tusso, left, and Paul Grams with the United States Geological Survey (USGS) use sonar equipment attached to a motorized raft to map the streambed profile along the Colorado River in Cataract Canyon and the ever changing silt that lines the canyon.

When the Piute Farms Waterfall formed, there was no plan to actively manage the situation and the same thing is happening on the Colorado, said Mike DeHoff, a former river guide who runs research trips through Cataract with the Moab-based Returning Rapids Project.

“Let’s make a conscious decision instead of just letting [a waterfall form],” DeHoff said. “As you weigh the two different options — sure, it could become a fish barrier, but it’s also going to serve as a sediment trap. And so if you want a healthier Colorado River in Cataract Canyon, we should put the river back in the channel.”

Sediment on the San Juan has backed up behind the waterfall into the river channel for dozens of miles, extending even beyond the boundaries of a full Lake Powell. The same thing could happen on the Colorado, potentially burying rapids that have started to reemerge.

DeHoff said an excavator could dig a canal down the old channel and as water runs through it during spring runoff, the river would theoretically cut through the softer sediment, abandoning the channel where the waterfall would form and allowing sediment to flow downstream.

(Francisco Kjolseth | The Salt Lake Tribune) A team of scientists manages their final obstacle after floating through Cataract Canyon, as they navigate the steep gravel ramp that is the North Wash takeout. With Hite Marina just down river decommissioned years ago due to Lake Powell’s dramatic drop over the years, boaters must now get creative to safely remove boats.

Shifting reservoir levels have made most boat ramps on Lake Powell useless, and the North Wash ramp has become steep and dangerous. For the last several years, commercial rafting outfitters have tied multiple vehicles together to back a trailer down the ramp or they use inflatable pontoons to roll rafts up the ramp.

Returning the river to its original channel could make it easier to construct a permanent boat ramp in the area, though if the river basin experiences several wet winters and Lake Powell partially fills again, the same problem could reemerge.

The great waterfall debate

Whether or not the fish barriers provide a net benefit to endangered fish is a matter of some debate among experts.

Keith Gido, a biology professor at Kansas State University who has done extensive research on the San Juan River, said he would support removing the Piute Farms Waterfall if the decision was reversible.

“These barriers fragment [endangered fish] populations above these reservoirs,” Gido said, acknowledging that the waterfalls also serve as barriers to nonnative fish. “It’s one of those things that we don’t really know what would happen until you do something about it.”

While the transportation program around the falls helps get fish upstream to spawn, it’s not clear if shocking fish before they spawn negatively effects reproduction. But if the open passage was causing more harm to certain species than good, then Gido would advocate for sending the river back over the waterfall.

(Zak Podmore | The Salt Lake Tribune) The U.S. Fish and Wildlife Service weighs an endangered razorback sucker below the Piute Farms Waterfall in southeast Utah on Tuesday, March 29, 2022.

“I would rather have the barrier,” Mark McKinstry, a research biologist with the Bureau of Reclamation, said of the Piute Farms Waterfall. “I think it’s worth more as a nonnative fish barrier than it is a problem for the native fish.”

“The waterfall [on the San Juan] gives us a very unique opportunity to look at a river, unlike the Colorado, that doesn’t have all of those nonnative fish,” he added. “We’ve got catfish, but we’ve pretty much eliminated carp.”

The San Juan carries more sediment than the Colorado, and nonnative species like smallmouth bass are already present in the system above the waterfall but have not yet caused problems, possibly because the San Juan is too muddy.

(Francisco Kjolseth | The Salt Lake Tribune) Zach Arens, a fish biologist with the Utah Division of Wildlife uses a hoop net near Gypsum Canyon to check for fish species and to see if humpback chub are possibly using the newly emerged rapids as habitat as Lake Powell recedes and more rapids emerge.

The potential waterfall near Hite would carry its own set of considerations.

Tom Chart, who recently retired as director for the Upper Colorado River Endangered Fish Recovery Program, said 10 years ago he would have been against a fish barrier forming at Hite. But the rapid spread of nonnative walleye through the Green and Colorado rivers in recent years has made him rethink that position.

“I think,” Chart said, “we would really love to see — if a waterfall formed — to see if there is a negative effect on the walleye that are roaming up from [Lake Powell] right now. … If it happens, we should gather as much information as we possibly can to inform potential future management decisions.”

Regardless of what the ultimate decision is regarding the Hite waterfall, Gido said we should keep the range of possible options in perspective.

“The big problem for endangered fish right now are these big dams,” he said, noting that nearly all of the razorback suckers on the San Juan are born in hatcheries. “It’s a little bit unfortunate that we’re stuck with trying to manage and manipulate things that are kind of trivial compared to the major problem of the dams.”

Zak Podmore is a Report for America corps member for The Salt Lake Tribune. Your donation to match our RFA grant helps keep him writing stories like this one; please consider making a tax-deductible gift of any amount today by clicking here.