After decades of campaigning, planning and effort, the demolition of four dams on the Klamath River near the remote California-Oregon border is scheduled to be completed this week – except for a few unanswered questions.

Considered the largest dam removal in U.S. history, this massive effort has long been the goal of the two states and their numerous partners, including Native American tribes. The goal is to remove old hydroelectric infrastructure from the 250-mile-long river and restore the Klamath and its native fish and wildlife populations, especially the endangered salmon runs.

While the completion of the dam demolition is a blow to many local residents who did not want to lose the popular lakes created by the dam, it is generally welcomed by environmentalists, fishing groups and the indigenous population.

“I’m excited, but also a little scared,” said Aaron “Troy” Hockaday, who sits on the Karuk Tribe’s tribal council. “I’ve never seen the river in its natural course. All the stories my grandmother and the elders have told about what the river used to look like… I’m very excited to see the progress that will occur.”

Even when the dams are fully removed, the $500 million project and whether it lives up to expectations will remain in the spotlight. In the coming years, migratory fish, which were prevented from migrating upstream by the dams and thus less successful at spawning, are expected to thrive as hundreds of miles of waterways are cleared. A major revegetation program at the former dam sites and the now-dry reservoirs that fed them, promises to revive the basin’s pristine landscape.

“There are still a lot of unknowns and a lot of ifs and hopes, but this is a great start,” Hockaday said.

After a year of demolition work, which included draining the reservoirs behind the dams to allow the river to flow through, workers recently cleared most of the dams themselves from the river. Now that those structures are gone from the channel, workers are working to restore the Klamath’s flow through the old dam sites that were drained for dam removal (the water was diverted into tunnels around the dam sites).

Once the flow resumes, which is expected later this week, the river will return to the historic course it had before the dam construction began over a century ago.

“This moment will be one of the most significant (of the project),” said Ren Brownell, spokeswoman for the Klamath River Renewal Corporation, the nonprofit charged with overseeing the dam removal. “It will be the moment when we have a free-flowing river.”

The river already flows through the areas where the 68-foot-high JC Boyle Dam in Oregon was demolished earlier this year and the smaller Copco 2 Dam in California was removed last year.

Over the next few days, workers are scheduled to reroute the river through the sites of the former 173-foot-tall Iron Gate Dam and the 126-foot-tall Copco 1 Dam, both in California. They will do so by removing small diversion dams called cofferdams that diverted the river around the dams during demolition. These are the same cofferdams that diverted the river when the dams were built and have been mostly submerged in reservoirs ever since.

“For (most) people, the dam removal is complete at this point,” Brownell said. “For the engineers, we have about two weeks of work after that.”

Parts of the dams on the river bank will be demolished in the next few weeks, as will the diversion tunnels.

The series of dams, known as the Klamath Hydroelectric Project, was created in the early 1900s and brought power and economic development to the region. In recent decades, however, the plants’ owner, Portland-based PacifiCorp, found that the electricity generated did not justify the rising costs of maintaining the plants.

At the urging of tribes and others, the company decided to demolish the old dams. Officials from California and Oregon helped formalize the initiative. The costs were covered by PacifiCorp and bonds approved by California voters.

The dams did not provide flood protection or store water, but they did serve as support for the reservoirs that became the backbone of several small lakeside communities in Siskiyou County that no longer have lakes.

Many residents are upset about the change, which has resulted in deteriorating views, lowering property values ​​and reducing recreational opportunities such as boating and fishing.

The Klamath River, which flows from the high desert of Oregon to the coast of Northern California, still has two large dams north of the site where the hydroelectric plant operated. These structures are equipped with fish ladders and are expected to be navigable for salmon.

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