On Wednesday, workers began breaching the last dams in a key stretch of the Klamath River near the California-Oregon border, allowing salmon to swim freely for the first time in more than a century.

These efforts are part of the largest dam demolition project in U.S. history.

The big picture: The removal process involves using excavators to remove the rock dams that diverted water upstream from two dams, Iron Gate and Copco No. 1, which have already been almost completely removed.

• This measure will give salmon access to this important habitat just in time for the Chinook salmon fall spawning season.

The headlines determine: This dam removal project precedes the scheduled completion of the removal of four massive dams on the Klamath and is in line with a nationwide movement to restore rivers to their natural flow and improve ecosystems for fish and wildlife.

• The project is representative of a larger trend of dam removal in the United States. As of February, more than 2,000 dams had been removed, reflecting a trend toward restoring natural rivers and ecosystems.

The background story: The Klamath River was once an important salmon river on the West Coast, but the construction of dams by PacifiCorp between 1918 and 1962 significantly disrupted the river’s natural flow and led to a drastic decline in the salmon population.

What we observe: The demolition of the four dams along the Klamath River is not expected to have a significant impact on electricity supplies, as these dams accounted for less than two percent of PacifiCorp’s energy production.

• The estimated cost of the project is approximately $500 million, and will be funded by taxpayers and PacifiCorp ratepayers.
• Despite the positive outlook for the return of salmon to their historic habitats and the recovery of the river, uncertainties remain regarding the timeframe for river recovery and the return of fish.
• Efforts are currently being made to revitalize the river and the salmon habitats. Initial successes are expected in the near future.

What they say: “Our sacred duty to our children, our ancestors and ourselves is to take care of the river, and today’s events represent a fulfillment of that obligation,” Frankie Myers, vice chairman of the Yurok Tribe, said in a statement.

• “I am excited to begin the restoration phase of the Klamath River,” Karuk Tribal Chairman Russell “Buster” Attebery said in a statement. “Restoring hundreds of miles of spawning grounds and improving water quality will help support the return of our salmon, a healthy, sustainable food source for multiple tribal nations.”