Suspended-sediment concentrations during dam decommissioning in the Elwha River, Washington
This document was prepared by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency and the National Park Service. Download the entire report, or read the Introduction below. Portions of this document were originally published in June 2013 and were updated in February 2014.
Introduction
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. During the project, USGS operated a turbidity sensor at a water-quality monitoring station in the lower Elwha River (fig. 1), which collected data at 15-min increments. The USGS also collected suspended-sediment samples from the lower Elwha River about 380 m downstream of the monitoring station. A relation between turbidity and suspended-sediment concentrations, consistent with established USGS protocols (Rasmussen and others, 2009), was established to enable reporting of suspended-sediment concentrations in the lower Elwha River.
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 September 2013. A time-series record of suspended-sediment concentrations is reported using continuous turbidity data as a surrogate for suspended-sediment concentrations.
Download the full report: Suspended-Sediment Concentration During Dam Decommissioning in the Elwha River, Washington