Desiree Tullos and Will Nuckoles clambered down a steep slope high above what used to be Iron Gate Reservoir in Northern California one mid-February morning. As they wound through buckbrush, trying not to slip on the gravelly soil, Tullos, an Oregon State University professor, lagged behind her graduate student, hampered by the boot cast on her broken right ankle. “I’m not supposed to put any weight on it,” said Tullos. “But I didn’t want to miss anything.”
As they neared a trail camera mounted on a metal stake, the view emerged: Sheer chocolate-colored cliffs slanted down to the bottom of the canyon, where the muddy brown Klamath River meandered through a raw and reborn landscape.
Iron Gate and two other reservoirs were drained earlier this year — a major step in removing the remaining dams of the Lower Klamath Project, which is scheduled to be completed by October. The near-simultaneous removal of four large dams — with a combined height of 411 feet — makes it the largest such project in U.S. history. Nuckoles and Tullos are among the dozens of university, agency and tribal scientists studying the river’s response to this enormous transformation.
The four Lower Klamath dams were built between 1911 and 1962, and, for decades, they blocked fish migration and trapped sediment behind them. Salmon runs, including chinook and coho, declined precipitously on what used to be the third-most productive river on the West Coast. Now that the dams have been breached, scientists expect 5 million to 7 million cubic yards of material, composed mostly of superfine clay and silt and dead algae, to surge downstream. Sediment is important to natural river systems; among other things, it helps distribute nutrients. But too much sediment can rob a river of oxygen, killing aquatic creatures, including the very salmon that dam removal is designed to help. Researchers expected that the first huge pulse of sediment would temporarily compromise water quality; consequently, drawdown was timed to minimize its negative impacts. Right before, crews from the Karuk Tribe also captured and relocated young coho from the main stem into tributaries to protect them.
Iron Gate and two other reservoirs were drained earlier this year — a major step in removing the remaining dams of the Lower Klamath Project.
Nuckoles has installed nine cameras around the two largest former reservoirs; each snaps an image every 15 minutes, enabling time-lapse videos that reveal the river’s evolution. Understanding how factors like the rate of drawdown and the nature of reservoir sediments affect erosion could help experts plan future dam removals or drawdowns to aid fish migration and service aging structures. (U.S. dams are, on average, 60 years old, and extreme weather linked to climate change is further stressing them.)
Nuckoles plucked the memory card out of the camera and plugged it into a laptop. Then he and Tullos settled on the ground to contemplate the river and surrounding mudscape. “I was really expecting a lot of deep, steep banks,” said Nuckoles.
Tullos explained that rapidly drained reservoirs show dramatic erosion, including conspicuous “knick points,” where water plunges over vertical slopes. But Iron Gate was drawn down relatively slowly. From this point on, Tullos didn’t expect any major sculpting and sloughing of banks. “Unless we get some big storms — that could totally change things.”
A U.S. Geological Survey team is among the many scientists tracking how the pulse of sediment affects water quality, fish habitat and vegetation as it moves downstream. In some cases, they’re using techniques developed especially for this project, several of which rely on USGS stream gauges that have been fitted with new sensors that can detect higher levels of turbidity.
“It’s a big collaborative effort,” said Liam Schenk, science advisor at the USGS Oregon Water Science Center. “This is this really exciting time for a lot of people that do this kind of work.”
ABOUT 30 RIVER MILES upstream from where Tullos and Nuckoles were checking cameras, the road from the J.C. Boyle Dam powerhouse in Oregon hugs the rugged basalt river canyon. In early March, you could still glimpse the twin penstocks plunging down to the powerhouse; far below, the Klamath roiled in shades of olive, taupe and foamy white.
Two water technicians for the Karuk Tribe — Larry Alameda, a Yurok tribal member, and Javon Mitchell (Karuk) — set up a field lab in the back of their pickup truck. They had just returned from a USGS stream gauge, where they collected river water in a special container called a churn. Now, Mitchell worked the churn’s plunger to keep the particles in the water suspended, while Alameda captured samples in various amber and white bottles.
“We go down to parts per billion on some of these samples,” said Alameda, who wore gloves to avoid contaminating anything. “It’s important to have good field practices.”
The Karuk Tribe, along with the Yurok Tribe and USGS, are conducting the water-quality monitoring required by the “Section 401” certification that was needed for the dam removal. At the lab, researchers will analyze Alameda’s samples for chlorophyll, particulate and dissolved carbon, and several forms of nitrogen and phosphorus; they’ll also look at turbidity and suspended sediment. The monitoring not only offers an ongoing snapshot of the water quality, it could also give them the chance to act if necessary — by moving fish out of harm’s way, for example.
Tribes with strong ties to the Klamath have long advocated for the removal of the dams. The Karuk Tribe, whose ancestral territory lies below them, has been monitoring water quality there for over 20 years.
Tribes with strong ties to the Klamath have long advocated for the removal of the dams. The Karuk Tribe, whose ancestral territory lies below them, has been monitoring water quality there for over 20 years. Its work has been critical to documenting the harmful toxins associated with the blue-green algae blooms that thrived in the reservoirs. “There were months out of the year when the river was glowing green,” said Alameda.
With the dams gone, the algae blooms should abate, and the river downstream should be warmer in spring but cooler in the summer — temperatures that favor native fish. Nutrients in the river will also change, said Grant Johnson, manager for the Karuk Tribe’s water-quality program, altering the algae and invertebrate communities that fish eat: “It’s a trickle-down effect.” The tribe aims to track those changes, adding to its already robust dataset. As early as this fall, the scientists may get a chance to see how returning salmon fare in these new conditions.
“I think that’s going to be mega-spawning habitat,” said Alameda, pointing to a broad, flat bend in the river, which, just two months ago, was submerged under the reservoir behind J.C. Boyle — a place salmon haven’t been able to access for over 100 years.
“It looks ugly now, but it will recover,” said Alameda. “There will be whole new traditions, with families coming up here to fish in the river.”
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This article appeared in the May 2024 print edition of the magazine with the headline “Researching a reborn riverscape.”
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