Researchers, tribes, residents prepare for a century of sediment released from the Klamath dams
Author: isi网站管理员-刘成 Source: Updated: 2024-01-03
Jefferson Public Radio | By Juliet Grable, 
 
Erik Neumann
/
JPR
Karuk Tribe Fisheries Program Manager Toz Soto (right) and three fisheries technicians net threatened coho salmon and other fish in the Klamath River in December 2023 to relocate them.

In the coming weeks, water will be let out from behind the three remaining dams on the Klamath River. A century's worth of sediment that has piled up behind the dams will also flow downriver.

There’s a bend on the Klamath River, just upstream of the small community of Happy Camp, where the river slows and sprawls just past a slope of fire-killed trees. There’s no cell phone service, and you’re far enough from Highway 96 that you can’t hear the few vehicles that pass by. It’s mid-December—not the ideal time of year for a swim, yet four men in black nylon dry suits are neck deep in the river, retrieving a fish trap from a quiet lobe of water on the river’s north bank.

The fyke net looks like a giant accordion, with a series of hoops that terminate in a funnel. It’s a known as a passive trap: fish swim in, but they can’t swim out. Once the men haul the trap to shore, they collapse it and carefully pour the catch into buckets. Toz Soto, fisheries program manager with the Karuk Tribe, plucks out a thick-bodied fish the length of his forearm and gently releases it back into the river.

“Small-scale sucker,” he calls out, while another crew member records it. “It’s good to see suckers in here.” A few fish later, he nets a slender silvery fish no longer than his little finger.

“Coho—a little guy,” says Soto, dropping the fish into a separate bucket. “He’ll stay in the river for at least another year before heading to the ocean.”

Erik Neumann
/
JPR
Fisheries staff with the Karuk Tribe search a seine net for fish in the Klamath River.

The crew from the restoration company Resource Environmental Solutions, or RES, and Northern California’s Karuk Tribe are spending two weeks catching as many young coho salmon as they can and relocating them to specially constructed ponds next to creeks. By doing so, they hope to protect the Endangered Species Act-listed fish from the deluge of sediment that will be released when water from three Klamath River reservoirs is released in January—a major step toward the removal of three major dams.

RES, the Karuk Tribe, and fisheries agencies have spent over three years planning for the relocation of the threatened salmon, which is taking place over 10 days in December.

“We’re talking 60 miles of river and we’re looking for these pockets,” says Dan Chase, director of Fisheries, Aquatics and Design for RES, which is heading up the restoration of the reservoir footprints in the wake of dam removal later next year. “We’re looking at these slower, shallower areas where coho like to hang out.”

Juliet Grable
/
JPR
Karuk Tribe Fisheries Program Manager Toz Soto transfers threatened coho salmon from the Klamath River into buckets. The fish will be released into nearby ponds in tributaries of the Klamath River to avoid harsh conditions during dam removal.

After checking the fyke trap, the crew wade out into the river again to deploy a seine net. They arc the net across the water, then move together toward the riverbank, drawing the curtain closed around the trapped fish. Then they huddle around the net, plucking and dropping fish into a bucket. Neither trapping method discriminates, and over the last two weeks they have caught coho, Chinook salmon, steelhead, Pacific lamprey, suckers, and dace, as well as non-native species like bullhead, sunfish, and bass. They keep the coho segregated in a special insulated cooler, young Chinook and steelhead in another. The rest are returned to the river.

If these young coho survive the initial disruption to the river, they could help make history. “These young fish could be some of the first adult coho salmon to return to a free-flowing Klamath River in over a century,” says Chase. “It’s even possible some of the fish moved during this effort could return to spawn above the Iron Gate Dam location.”

Short-term pain for long-term gain

Scientists, fishermen, and environmentalists agree that removing the four dams of the Lower Klamath Project will benefit anadromous fish like salmon, steelhead, and lamprey. But the process will have “unavoidable negative short-term impacts on aquatic species that we all want to protect,” says Dave Meurer, director of community affairs for RES. “You will see dead fish on the banks.”

Tens of thousands of dead fish began surfacing in a 50-mile section of the Klamath River after a debris flow in August 2022 following the McKinney Fire.
Karuk Tribe Department Of Natural Resources
Tens of thousands of dead fish began surfacing in a 50-mile section of the Klamath River after a debris flow in August 2022 following the McKinney Fire.

The four dams were built between 1903 and 1962. The smallest, Copco 2, was completely removed this October.

“There's about 17 to 20 million cubic yards of sediment built up behind the three remaining dams,” says Ren Brownell, spokesperson for the Klamath River Renewal Corporation, the entity charged with dam removal. “Through the drawdown process, we expect five to seven million cubic yards of sediment to go downstream.”

That's enough to fill between 1,500 and 2,100 Olympic-sized swimming pools of material, most of it extremely fine, talc-like silt and clay—and lots of dead algae.

“As that [algae] makes its way downstream, it decomposes,” says Desiree Tullos, professor of water resources engineering at Oregon State University. “That process sucks oxygen out of the water.”

KRRC has decided to rip the Band-Aid off and drain all three reservoirs near simultaneously—first Iron Gate, then J.C. Boyle about a week later, then finally, Copco Lake. This slightly staggered approach ensures more of the sediment will slough into the flowing river rather than being stranded along the disappearing lake shores. Crews with RES will help wash the sediment downriver as reservoir levels drop.

Juliet Grable
/
JPR
Copco 1 dam in December, 2023, prior to the reservoir behind it being drawn down.

“Picture big fire hoses either on boats or on the shore trying to just spray down and mobilize as much of that material as possible,” says Meurer. “And then what's remaining is what we're going to plant.” Almost immediately after, crews will start seeding and planting trees, shrubs and flowering native plants on the exposed banks.

Testing conducted by the EPA in 2009 and 2010 and more recent testing conducted by KRRC’s consultants confirmed that the reservoir sediments contain low levels of contaminants and they can be safely released downstream. Nevertheless, some residents who live near the river are nervous.

“I do worry about the sediment coming down from JC Boyle,” says Linda Ebert, who lives on the north shore of Copco Lake. “We've been assured more or less that the EPA reports on it that it's not that toxic. But I don't have a whole lot of faith in those reports, quite frankly.”

Other residents are concerned about dust that will form once the muddy footprints of the reservoirs dry out and before new vegetation takes root. Resident Francis Gill sees parallels with Condit dam, which was removed from the White Salmon River in Washington State in 2011.

“For the first year or two, I guess, the dust was kind of a big issue up there, until the grasses and everything kind of filled in,” says Gill. “So, if it's toxic, you can see how the wind can blow around here in the afternoons. It comes from down river and blows up canyon.”

Juliet Grable
/
JPR
Residents of Copco Lake Danny Fontaine, Linda Ebert and Francis Gill. They worry about the effects of sediment traveling downriver to their community.

A river of chocolate milk

Each dam removal adds to the body of knowledge around how rivers recover from these barriers. But it’s also important not to make assumptions about one dam removal based on another, says Tullos. For instance, the removal of two dams on the Elwha River, also in Washington, didn’t have a big impact on water quality.

“There was a lot of sediment, but it was coarse—like gravel and sand,” says Tullos. The distance of the dam from the river mouth, the nature of the built-up sediment, how quickly the dam is breached—all of these play a role in where and how quickly the material moves downriver.

As the reservoirs are drawn down, all of the water and sediment will gush through a 14-foot wide tunnel at the base of Iron Gate dam. The release will be relatively controlled compared to Condit dam, which was breached with a dramatic blast. Even so, the first pulse will turn the river into “chocolate milk,” says Tullos. Most of the finer silt and clay will likely stay suspended in the river all the way out to the ocean but coarser material will fall out in the stretch of river below Iron Gate. That’s a good thing, says Chase.

“One of the benefits of dam removal is going to be recovering and re-establishing the more natural movement of sediment from upstream to downstream,” he explains.  

This should help build habitat for a suite of native creatures, including salmon, which dig their nests in fine gravel, and lamprey, which spend the first part of their lives burrowed into silt and sand. The sediment should also help scour off the colonies of worms that host C. shasta, a disease organism that plagues Chinook salmon. In some years, over 90% of the fish sampled below Iron Gate dam have been infected with C. shasta and likely died.

The US Bureau of Reclamation has been releasing large pulses of water from Upper Klamath Lake to dislodge the worms. Hopefully, once the dams are gone, these “flushing flows” won’t be necessary, and the natural movement of sediment will help keep the worms—and C. shasta—in check.

Meanwhile, Tullos and graduate student Christine Alfred have installed dissolved oxygen sensors below the dams and will use these and existing USGS gauges to track water quality following drawdown.

“The goal of that is to understand what is really driving that extraction of oxygen from the river, which is important for fish, right?” says Tullos. “Fish need oxygen.” Their work will piggyback on monitoring by USGS and the Karuk and Yurok Tribes, which will be tracking how the sediment affects water quality, fish, and the shape of the river itself.

Greenhouses for coho

After a morning of trapping fish, Soto’s crew meets up with a second group at Alexander pond, which was constructed along Seiad Creek, a small tributary of the Klamath. Trucks angle over the grassy flat above the pond, and crew members sit on tailgates, some munching on sandwiches and nut bars.

They’ve already released the steelhead and Chinook lower down in the creek, but the coho are getting the VIP treatment. After technician Harold Mitchell weighs, measures, and fits each fish with a tiny tag, they’ll go into the pond, which was built 13 years ago specifically for coho like these to grow strong and healthy.

Erik Neumann
/
JPR
A juvenile coho salmon being weighed and PIT tagged before being put in a pond off of Seiad Creek.

“The funny thing about this pond was, we really didn't have any design standards at that point,” says Soto. “We were kind of like, okay, we're just gonna dig a hole and see what happens.” Coho, which can spend one, two, or even three years in rivers and creeks before heading to sea, flocked to the pond; even adult fish have returned there. Since that first experiment, the Karuk Tribe and Mid Klamath Watershed Council have built 35 of these ponds alongside several tributaries. The ponds stay cooler in summer and warmer in winter, and fish grow fat fast—“coho greenhouses,” Soto calls them.

And now, those same ponds will serve as refuges from the disruption of dam removal. By the end of their ten days of trapping, they will have captured and relocated 245 young coho.

Any salmon or other fish remaining in the main stem of the Klamath River will know what to do should water quality plummet, says Soto. “I have a lot of faith that the fish that do stay [in the river], if water quality gets too bad, they'll move. There's plenty of tributaries around here where they can find refuge.” His crew will turn to monitoring and reacting once drawdown begins on January 11; if they find fish crowding around creek mouths, they will consider moving them to safety. But first, he’ll take a moment to celebrate the milestone that’s been decades in the making, and which now feels as inevitable as the flowing river itself.

“As soon as they blow the plugs, I'll be drinking a beer and going okay—there’s no turning back now,” says Soto.

Juliet Grable
/
JPR
Fisheries technicians from RES and the Karuk Tribe using a fyke net to catch fish in the Klamath River before water is let out of three dams.



(Source: https://www.ijpr.org/environment-energy-and-transportation/2024-01-02/researchers-tribes-residents-prepare-for-a-century-of-sediment-released-from-the-klamath-dams)

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