Fig. 6

Sediment plume triggered by Elwha Dam demolition in the State of Washington (USA). a. index map showing Elwha Dam (arrow). The 108-ft dam, built in 1910 and demolished in 2012, is located approximately 7.9 km upstream from the river mouth. Credit: U.S. Geological Survey Public Domain map; b Aerial photograph of the Olympic Peninsula and the Strait of Juan de Fuca. Note the Elwha River mouth is shown by a filled yellow circle. From Duda et al. (2011) with additional labels by G. Shanmugam; c Elwha sediment plume triggered by the demolition of Elwha Dam in 2012. Red arrow shows easterly deflecting plume, away from the Pacific Ocean. This deflection could be attributed to tidal currents in this estuarine environment. Also, the Strait of Juan de Fuca is subjected to easterly upwelling winds. Photo credit: Tom Roorda. Aerial photo was taken on March 30, 2012. From Hickey (2013), UW News, March 7, 2013, University of Washington, Seattle, WA; d Aerial photo of Elwha River mouth showing absence of sediment plume in 2019 (compare with c). Photo courtesy of Tom Roorda, Roorda Aerial, Port Angeles, WA. Aerial photo was taken on February 28, 2019