First sighting of salmon in 100 years marks key milestone for California dam removal

For the first time in more than a century, a salmon was observed swimming through Klamath River waters formerly blocked by Iron Gate Dam. Iron Gate and three other dams were demolished in a massive dam-removal project that recently wrapped up. Carlos Avila Gonzalez/The Chronicle

In an early victory for the nation’s largest dam-removal project, the first salmon in more than a century is believed to have pushed up the Klamath River this past week into waters formerly blocked by dams.

Scientists with the nonprofit California Trout told the Chronicle that their sonar camera captured what was almost certainly a chinook salmon migrating upstream Thursday past the site where Iron Gate Dam once stood, just south of the California-Oregon border.

The roughly 2½-foot-long fish is thought to be part of the Klamath River’s fall run, the first and largest run of salmon expected to benefit from the recent removal of four hydroelectric dams on the 250-mile waterway.

“This fish marks the beginning of the recovery for the fishes of the Klamath,” said Damon Goodman, a fish biologist and regional director at California Trout. “This is testament to the success of dam removal and marks a new beginning for the Klamath River.”

Since the early 1900s, the construction of four hydroelectric dams has kept fish from swimming to hundreds of miles of upstream waterways in what was once the third-largest salmon-producing river in the West. The lack of access to these cold waters for spawning is one of the reasons for the steady demise of California’s iconic salmon population.

While the decades-long push to raze the dams was billed as a restoration of the Klamath River’s entire ecosystem, the central driver of the project was the fish.

A collaboration of nonprofit, state and federal scientists has been monitoring fish movement in and around the site of the former Iron Gate Dam since dam removal wrapped up over the past few weeks. Iron Gate was the southernmost of the four demolished dams.

At 10:06 p.m. Thursday, the sonar camera at the site recorded a fish swimming upriver, which the scientists discovered Friday when they were reviewing footage. The equipment does not photograph the fish, but from the images created by ultrasonic waves transmitted through the water, the scientists have little doubt that the fish is a chinook salmon.

Salmon had been observed just south of the area in recent weeks.

The fish are generally born in the river, then swim to the ocean and stay there for two to three years before returning to their birthplace to spawn. The fall run of fish is named for the time of year the salmon come back to the river.

The $500 million dam-removal project, which sought to […]

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