Suspended-sediment concentrations during dam decommissioning in the Elwha River, Washington

ABSTRACT: In 2011, the National Park Service commenced the incremental removal of two century-old dams along the Elwha River, Washington, in order to restore ecological and sediment-delivery processes. In cooperation with the U.S. Environmental Protection Agency and the National Park Service, the U.S. Geological Survey (USGS) was asked to measure turbidity and calculate suspended-sediment concentrations in the lower Elwha River during the dam-decommissioning and river-restoration project. This document contains calculations of total suspended-sediment concentrations and concentrations of suspended-sediment fines (particle sizes less than 0.0625 mm) in the lower Elwha River downstream of the dam decommissioning project from September 2011 to February 2013. A time-series record of suspended-sediment concentrations is reported using continuous turbidity data as a surrogate for suspended-sediment concentrations