One of the greatest natural experiments of all time will start in 2012 when the National Park Service begins the removal of two hydroelectric dams on the Elwha River in the Olympic National Park (ONP). The Elwha Restoration Act of 1992 (PL102-495) has authorized $185 million in federal funds for demolition and clean-up, as well as provision to reintroduce salmon and to protect water quality. In the years that follow the opening of the river, a world-famous salmon fishery, abruptly eliminated in 1911 by construction of the first dam, will be restored. As the salmon move upstream to spawn and die, the marine-derived nutrients in their bodies will be returned to the forest along 113 km of wild river. Several hundred thousand salmon will eventually repopulate the river annually, bringing a huge quantity of nutrients that will permeate throughout the ecosystem. Because all of the water above the upper dam is in the ONP, these ecological changes will be available for long-term study, without the confounding influences of human disturbance that are common in virtually all other river restoration projects. Thus, the Elwha dams, by far the largest ever to be removed, constitute a unique opportunity to study the recovery of a riparian ecosystem, with profound implications for the value of dam removal elsewhere as a general conservation strategy
A large-scale, long-term biotic survey and inventory of the Elwha River Valley has been initiated focusing on microorganisms, lichens, mosses, liverworts, fungi, insects, and spiders—taxa that are least known and most vulnerable to change when the dams are removed—that inhabit the riparian habitat above, between, and below the two dams. Although only 130 km from Seattle, the Elwha biota is poorly known—very little non-vascular plant and invertebrate collecting has ever been done, and most of what has been collected has been lost or discarded, leaving few voucher specimens to back-up the inadequate body of published taxonomic information. The work described here will correct these deficiencies by bringing together professional taxonomists and an assemblage of agency, tribal, academic, and citizen scientists to collect, identify, inventory, and permanently archive the current mix of non-vascular plants and invertebrates of the Elwha before the dams are removed.
Dam removals are increasingly viewed as a means of restoring riverine ecosystems, especially in the Pacific Northwest where salmon stocks are seriously depleted and many rivers are closed to fish migration. The Elwha project provides ideal conditions for testing hypotheses related to river restoration. If dam removal is beneficial here, the knowledge gained can be applied anywhere; but, if salmon restoration is less than successful under these ideal conditions, the implications for rivers elsewhere are dire. The work will provide the evidence needed to evaluate the success or failure of dam removal. Finally, assuming a successful return of the salmon fishery, this project hopes to contribute to the effort of restoring to the Lower Elwha Klallam Nation what was abruptly taken away from them nearly a century ago.