Starting in 2011, the National Park Service removed two obsolete dams from the Elwha River in Olympic National Park, Washington.
Starting in 2011, the National Park Service removed two obsolete dams from the Elwha River in Olympic National Park, Washington. It was the world’s largest dam-removal project. Over the next five years, water carrying newly freed rocks, sand, silt and old tree trunks reshaped more than 13 miles of river and built a larger delta into the Pacific Ocean.
Scientists from the U.S. Geological Survey and six research partners recently published a paper summarizing a half-decade of changes to the shape and sediment of the Elwha River after dam removal.
Of the 33 million tons of sediment trapped behind the dams, about 8 million tons resettled along the river or at the mouth, and another 14 million dispersed into the ocean. It would take more than 70 dump trucks running 24 hours a day for five years to move that much dirt and debris downstream. Piled up, the sediment would form a cone about one-third of a mile in diameter and taller than a 50-story building.
Continue reading at USGS.
Image via USGS.
