The world’s largest dam removal and restoration project currently underway on the Klamath River in Oregon and California will aid salmon populations that have been devastated by disease and other factors. However, it will not fully alleviate challenges faced by the species, a team of researchers conclude.
“The dam removals will likely go a long way towards restoring balance in the river,” said Sascha Hallett, a fish parasitologist at Oregon State University who has studied the river for two decades. “Certainly under certain circumstances there are going to be disease outbreaks, like with people and pathogens. But we envision that they are not going to be as large and not going to be as frequent as we have observed in the past.”
Michael Belchik, a fisheries biologist with the Yurok Tribe in California and co-author of the paper, said he thinks there will be noticeable gains for fish shortly after the dams are removed.
“I think you are going to see fish accessing new habitat right away, and that is going to be a cause for celebration,” said Belchik, who has worked for the Tribe since 1995.
In the paper, published in Frontiers in Ecology and Evolution, Hallett and a team of researchers from Oregon State, Tribes in Oregon and California, and state and federal agencies outlined their predictions for salmon disease risk in the Klamath River following the removal of four hydroelectric dams. They also provide post-dam removal research and monitoring recommendations and insights to aid habitat restoration efforts.
One of the four dams was removed earlier this year, and the other three are slated to be taken down in early 2024. Removal of the dams will result in restoration of habitat originally altered more than 100 years ago with construction of the first dam.
The Klamath River runs more than 250 miles from Oregon’s high desert interior through the Cascade Mountains before entering the Pacific Ocean in northern California. It has broad ecological, cultural, recreational and economic relevance. The river was once the third largest salmon-producing river on the West Coast. Those salmon served as the foundation of life and culture for Tribes living along the river.
Construction of the dams in the early-to-mid-20th century blocked access for salmon and other fish species to hundreds of miles of habitat and created barriers that led to increases in pathogens deadly to the fish.
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