For decades, resource managers agreed that removing the two dams on the Elwha River would be a big win for the watershed as a whole and, in particular, for its anadromous trout and salmon. The dams sat on the river for more than 100 years, trapping approximately 30 million tonnes of sediment behind their concrete walls. As the dams were removed between 2012 and 2014, much of this sediment was released downstream—and scientists had little comparisons to draw from to understand what this sediment load would do to the marine ecosystem at the mouth of the river.