One year ago the Elwha and Glines Canyon Dams started to be removed as part of the watershed restoration on Washington’s Olympic peninsula. It is the largest dam removal in the history of the USA.
The dam removal will restores ecosystems in the long term, it will open up the river to migrating fish for the first time in 100 years and allow the river to transport sediment throughout its reach, helping to rebuild the natural bed structure and flow of the Elwha all the way to the sea by rebuilding beaches that today are starved for sand and other fine material.
In the short term, excess turbidity remains the biggest concern during the next 3–10 years. About 600 dams have been taken down in the U.S. over the past 50 years, but none involved so much sediment (24 million cubic yards).
In the case of the Elwha, Congress authorized the dam removal 20 years ago, but it took two decades to get the money and logistical details in place.