Ecosystem response to the removal of the Elwha River dams

3:10pm  |  Paccar Environmental Technology Building (PETB) Room 202

Dr. George Pess, National Oceanic and Atmospheric Administration (NOAA)

Worldwide stream and watershed restoration efforts cost billions annually. Normally, these projects are typically local-scale activities that do not have a measurable effect on ecosystem function or services. We present results from the Elwha River, where the largest dam removal ever undertaken resulted in measureable ecosystem changes. The release and transport of tens of millions of metric tonnes of sediment from former reservoirs has resulted in the transformation and rebuilding of estuarine and riverine habitats. The resumption of free passage for aquatic organisms has re-established anadromous fishes to areas that have been void of such species for 100 years and altered the migration patterns and improved the fecundity of a song bird. Our results demonstrate the critical importance of maintaining longitudinal connectivity for watershed processes and ecosystem services.