Restoration of the Elwha River Ecosystem and Anadromous Fisheries

摘要

Historically, the Elwha River in western Washington was renowned for an abundance and diversity of anadromous salmonids. Most of the river lies within Olympic National Park and remains in pristine condition but two dams in the lower river have blocked all anadromous fish for more than 80 years. To restore the Elwahs's historic fishery resources and resolve an impasse about federal licensing of the dams, the U.S. Congress passed the Elwha River Ecosytmem and Fisheries Restoration Act in 1992. The act required an anlysis of alternatives (dam retention with fish passage facilitites versus dam removal) to achieve full ecosystem and fishery restoration. Analysis indicates that removal of both dams is the only alternative that will achieve full restoration, but dam removal and fish restoration efforts could span 20 years and cost from 154 million to 210 million. Although fish restoration poses problems because of limited native runs, sediment management presents the most significant environmental challenge and cost. An Environmental Impact Sstatement is now in preparation and baseline studies are underway to examine and describe changes to wildlife communities, water quality and chemistry. vegetation, aquatic insects, and resident fish populations. The Elwha River restoration project provides an excellent opportunity to examine the role and contribution of anadromous salmonids to ecological processes in Pacific Northwest ecosystems.