For the first time in over a century, salmon will soon be able to swim freely through the Klamath River and its tributaries – a vital watershed near the California-Oregon border – as the largest dam removal project in U.S. history nears completion.

This week, excavators will be used to breach rock dams that have diverted water upstream of two dams that have already been almost completely removed: Iron Gate and Copco No. 1. The work will allow the river to flow freely again in its historic bed and allow salmon passage to key habitats just in time for the Chinook salmon spawning season in the fall.

“The fact that the river is being returned to its original bed and the dam is gone is a good omen for our future,” said Leaf Hillman, ceremonial leader of the Karuk tribe, which has been fighting to remove the Klamath dams for at least 25 years. Salmon are culturally and spiritually important to the tribe, as well as others in the region.

The demolition came about a month before the demolition of four massive dams on the Klamath was scheduled to be completed. The demolition was part of a nationwide movement to return rivers to their natural flow and restore ecosystems for fish and other wildlife.

As of February, more than 2,000 dams had been removed in the U.S., most in the past 25 years, according to the advocacy group American Rivers. Among them were dams on Washington state’s Elwha River, which flows from Olympic National Park into the Strait of Juan de Fuca, and the Condit Dam on the White Salmon River, a tributary of the Columbia.

“Now the healing can really begin because the river can regenerate,” said Joshua Chenoweth, chief riparian ecologist for the Yurok Tribe, who has fought for decades to remove the dams and restore the river. “Humans can do a lot to help, but what we’ve learned with Elwha and Condit and other dams is that all you really need to do is remove the dams, and then rivers can return to their natural state really well.”

The Klamath was once the third-largest salmon river on the West Coast. But after energy company PacifiCorp built the dams to generate electricity between 1918 and 1962, the structures disrupted the river’s natural flow and interrupted the life cycle of the region’s salmon, which spend most of their lives in the Pacific Ocean but return to their home rivers to spawn.

The fish population declined dramatically. In 2002, a bacterial outbreak caused by low water levels and high temperatures killed more than 34,000 fish, mostly Chinook salmon. This was the beginning of a decades-long effort by tribes and environmental groups that culminated in 2022 when federal authorities approved a plan to demolish the dams.

Meanwhile, the smallest of the four dams, the so-called Copco No. 2, has been removed. The reservoirs of the other three dams have also been emptied and demolition of these structures began in March.

Along the Klamath, the dams will not have a major impact on power supplies. At full capacity, they produced less than 2% of PacifiCorp’s energy – enough to power about 70,000 homes. Hydropower from dams is considered a clean, renewable energy source, but many larger dams in the Western U.S. have become targets of environmental groups and tribes because of the damage they cause to fish and river ecosystems.

The estimated cost of the project was approximately $500 million, which would be paid for by taxpayers and PacifiCorps taxpayers.

However, it is unclear how quickly salmon will return to their original habitats and the river will recover. There are already reports of salmon at the river mouth beginning their journey. Michael Belchik, senior water policy analyst for the Yurok Tribe, expressed hope that they will pass the Iron Gate Dam soon.

“I think we’re going to have some initial success,” he said. “I’m pretty confident we’re going to see some fish swim over the dam. If not this year, then certainly next year.”

There are two more Klamath dams further upstream, but these are smaller and allow salmon to pass through fish ladders – a series of pools through which the fish can jump to pass the dam.

Mark Bransom, executive director of the Klamath River Renewal Corporation, a nonprofit organization that oversees the project, pointed out that it took about a decade for the Lower Elwha Klallam Tribe to start fishing again after the Elwha dams were demolished.

“I don’t know if anyone knows for sure what this means for the fish to return,” he said. “It’s going to take some time. You can’t undo 100 years of damage and impacts to a river system overnight.”