Nearly a century after they rose up and blocked the Elwha River to generate power, two dams on the river with headwaters in Olympic National Park will begin to be removed this weekend in a historic event aimed at restoring the park's largest watershed.

The event is so huge that Interior Secretary Ken Salazar and other dignataries will be present Saturday to help mark the occasion by symbolically removing a chunk of the Elwha Dam. After that, it will take several years for the Elwha and Glines Canyon dams to be removed from the landscape, which is to be recontoured as closely as possible to how the river ran prior to the dams' construction.

"Expected to last three years, the event marks a significant milestone for the Elwha River Restoration project which will help increase salmon populations, uphold commitments to the culture of the Elwha Klallam Tribe, and create new opportunities for growth and regional vitality," an Interior Department release said.

The Elwha and Glines Canyon dams were built in the early 1900s. While they generated power, they also severed some of the largest salmon runs outside of Alaska. By some estimates, the fish populations in what had been one of the most productive areas in the country declined by 95 percent or more, and the loss of sediment carried downstream by the former river had major impacts on the ecosystem at the mouth of the river.

How—or whether—to deal with these impacts has been the topic of years of study and debate, but the decision was finally made to remove the dams at a cost of roughly $350 million as the most effective way to restore the Elwha.

What do you get for that much money?  "... (P)urchase of the two dams and hydroelectric plants from their previous owner, construction of two water treatment plants and other facilities to protect water users, and construction of flood protection facilities, a fish hatchery and a greenhouse to propagate native plants for revegetation."

Only one of the two dams—Glines Canyon—is located inside the park, but the upper reaches of the Elwha River are within the park boundary. As a result, the National Park Service has overall responsibility for the project, while other agencies have key roles. The U.S. Bureau of Reclamation, which currently operates and maintains the dams, was the lead agency in designing dam removal and sediment management strategies.

Once the work is completed, salmon populations are projected to swell from roughly 4,000 to possibly as many as 400,000, as all five species of Pacific salmon return to more than 70 miles of river and stream. Removing the dams will also reestablish the river's natural flow of sediment from the mountains to the coast—rebuilding wetlands, beaches, and the estuary at the river's mouth.

The project is expected to have more benefits than simply more fish in the river, as nutrients are expected to get a significant boost throughout the watershed. According to park officials, researchers intend, among other things, to study "(M)arine-origin nutrients, recolonization of streams by anadromous fish, changes in river sediments and spawning habitat, vegetation recolonization and change in distribution, wildlife habitat changes, wildlife population and distribution dynamics."

Too, according to David Graves, the Northwest program manager for the National Parks Conservation Association, the restoration work will return some important landscapes to the Elwha Klallam Tribe. The building of the dams, he says, violated some of the tribe's treat rights and also inundated some important spiritual sites.

“It’s been a long time coming," Mr. Graves said Tuesday. "We’re very excited about this project. We’ve been working on it for cquite a while with a lot of other conservation organizations."

Not only should the project restore the Elwha River watershed, but the work should serve as a model for future dam removals, he said, and show "how river ecosystems can restore themselves."

Of course, the river won't heal itself over night, but rather over a number of decades, the NPCA representative said.

Removing the dams also isn't expected to adversely affect power delivery to a paper mill in Port Angeles that is the only beneficiary of the hydropower, said Mr. Graves.

“It’s not a very large amount of power, and the Bonneville Power Administration says they can easily shift resousrces on the power gride to make up the losses to the paper mill at no additional cost, the same rate they’re paying now,” he said.

To see animations of how the dams will be removed and the landscapes restored, view the videos that are linked to on the bottom of this NPCA page.
 
You can learn more about the restoration project and related research at this site. Saturday's ceremony is to begin at 11 a.m. PDT, and will be streamed live at this site.

Jim Burnett contributed to this article.