The Elwha River

The Elwha River drains the largest basin in Olympic National Park and has huge potential for salmon recovery in the Puget Sound region. For more than 90 years, the natural flow of the Elwha River has been altered by the presence of two dams. These dams have interrupted the normal flow of sediment and debris to the shore and prevented anadromous salmon from accessing pristine habitat in the park. The Department of the Interior is planning to remove the dams in 2009 to restore the physical and biological integrity of the river ecosystem. Restoration of the river will be a significant and unprecedented Federal contribution to salmon recovery in the region, but many questions remain about the river’s response to dam removal and the recovery process for salmon.

A unique opportunity exists to examine the ecosystem response to the dam removals. Studies of the physical and biological effects of dam removal will be grouped into three general categories: ecosystem responses, flow modification and sediment transport, and cultural resources. Ecosystem processes will be monitored along the river and nearshore before and after the removal of the dams. Work under consideration includes mapping of shelf, nearshore, and beaches as well as salmon habitat; monitoring of coastal processes; and river sediment and nearshore computer modeling.