Dam Removal to Restore Elwha River in US

Large Hydroelectric Dam Demolition by National Park Service to Destroy Last 30 Feet and RebuildRiverbank

The removal of the Glines Canyon Dam and the Elwha Dam, a smaller downstream dam,began in late 2011. Three years later,salmon are migratingpast the former dam sites, trees and shrubs are sprouting in the drained reservoir beds, and sediment once trapped behind the dams is rebuilding beaches at the Elwha's outlet to the sea. For many, the recovery is the realization of what once seemed a far-fetched fantasy.

Before the Park There Was the River

The Elwha runs for 45 miles, from the Olympic Mountains to the Strait of Juan de Fuca, and all but its final five miles lies within what is nowOlympic National Park. Long before the park was established in 1938, the river was regionally famous as the richest salmon river on the Olympic Peninsula. For generations, theLower Elwha Klallam Tribe, whose members live at the mouth of the Elwha, depended on the river's fish and shellfish for survival. But the peninsula was also famous for its massive trees, and in the early 1900s, the local timber industry needed power for its mills and its growing ranks of workers.

Fish were no match for finance, and the 108-foot-high Elwha Dam, located five miles upstream from the river's outlet, started generating power in 1914. "There is no question but that the Elwha is harnessed at last and forever," a local newspaper reporter crowed at the time. The larger Glines Canyon Dam, eight miles further upstream and inside what is now Olympic National Park, began operations in 1927.

A Slow Demolition

It would take nearly two decades more for dam demolition to begin—much longer than it took to build the dams in the first place. The timber industry and some local communities opposed the idea, and U.S. Senator Slade Gorton of Washington blocked federal funding until he was voted out of office in 2000.

Though a few smaller dams had been removed from U.S. rivers, no one one had attempted a dam removal as large as the one proposed for the Elwha. The unknowns were daunting: What would happen to the estimated 27 million cubic yards of sediment (21 million cubic meters)—enough to fill the Seahawks' CenturyLink Field nine times over—trapped behind the dams? How would salmon and other wildlife respond to a free-flowing river? How would tribal members and other nearby residents be affected?

In 2004, the tribe, the National Park Service, and the city of Port Angeles reached an agreement on dam removal. The dams would be taken down in several stages, allowing for a relatively gradual release of sediment. Two water-treatment facilities would be built to protect local water supplies, and the tribe would receive federal funds for a new, larger fish hatchery.

Finally, on September 15, 2011, a barge-mounted excavator began chipping concrete off the upstream face of Glines Canyon Dam. Removal of the Elwha Dam began later that week. At a ceremony by the river, formerSenator Bill Bradleyof New Jersey praised the demolition of the dams in terms that wouldn't have sounded out of place at their inauguration. "The reflection you see in Elwha is an image of what our country is capable of," he told the crowd.

Six months later, the Elwha Dam was gone, and the river flowed in its original channel for the first time in more than a century. Steelhead and coho salmon transplanted above the dam site spawned in the river's tributaries, and juvenile coho were spotted. In the summer of 2012, Chinook salmon began migrating up the river, and by the following fall, they too had spawned in tributaries and in the Elwha mainstem.

The River Returns

Over the past three years, the sediment trapped behind the dams has washed downstream, rebuilding riverbanks and gravel bars and, in and around the river's mouth, creating some 70 acres of new beach and riverside estuary habitat for Dungeness crabs, sand lance, surf smelt, clams, and other species. On the ocean bottom just offshore, what used to be a kelp-covered expanse of cobbles is now blanketed with mud and sand, also good habitat for crabs and sand lance.

Source: National Geographic

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