THE ELWHA RIVER
The Elwha is a 72 km (45 mile) long river located on the Olympic Peninsula in the northwestern part of Washington state. The source of the Elwha lies in the Olympic Range of the Olympic National Park. The park, a World Heritage Site, is renowned for the diversity of its ecosystems. Glacier-clad peaks interspersed with extensive alpine meadows are surrounded by an extensive old-growth forest, including the best example of intact and protected temperate rainforest in the Pacific Northwest (UNESCO). Eleven major river systems drain the Olympic mountains, offering some of the best habitat for anadromous fish species in the country. The Elwha is one of the largest of the eleven and flows north, eventually draining into the Strait of Juan de Fuca.
Fig. 1. The Elwha River and its tributaries, showing the location of the Elwha and Glines Canyon dams. Smaller numbers in italics along tributaries denote the distance (km) to an anadromous barrier. Upstream migrations of Pacific salmonids after dam removal are expected to extend at least 70 km up-river. After Brenkman et al. (2008).
Historically the Elwha was one one of the most productive salmon rivers for its size in the Pacific Northwest, and one of the few that supported all anadromous salmonids native to the region (Wunderlich et al., 1994). For millennia, Native Americans of the Lower Elwha Klallam Tribe lived and fished year-round along its banks and tributaries (Swan, 1857; Wood, 1989). Their early camping areas, residential sites, and large villages all identify a culture closely tied to the vast and multiple runs of salmon and steelhead (Anonymous, 1995). The Elwha Klallams depended on ten anadromous fish runs that then populated the river (Duda et al., 2008). But soon after pioneers established themselves on the Olympic Peninsula in the late nineteenth century, interest in damming the Elwha River for electric-power generation became a priority (Allaway, 2004). In 1889, Thomas Aldwell, a Canadian entrepreneur, began to purchase land along the Elwha. By 1910 he had obtained the needed land, and with financial help from George Glines, a real estate investor from Winnipeg, he established the Olympic Power and Development Company. As a consequence, the Elwha Dam (32-m high and 124-m wide at the top) was built between 1910-1913, approximately 8 km from the river mouth, eventually forming a 4.5-km long reservoir called Lake Aldwell (Fig. 1).
A second dam, Glines Canyon Dam (64-m high and 82-m wide), was constructed for additional power generation in 1925-1927, about 21.6 km upriver from the mouth. It eventually formed Lake Mills, 4.0-km long. Although dams in Washington State were legally required to provide for passage of migrating fish, both the Elwha and Glines Canyon dams were built without a fish ladder or other provision for fish passage. A hatchery was built at the Elwha Dam to compensate, but it was unsuccessful and closed in 1922 (Allaway, 2004).
Consequences of Dam Construction.—For nearly a century, anadromous salmon and steelhead have been restricted to the lower 8 km of the Elwha River and its tributaries. The size of each of the anadromous runs has shrunk drastically (Anonymous, 1994, 1995; Scharf, 1998; Foster Wheeler, 2000; Allaway, 2004; Duda et al., 2008). At least one stock (sockeye) is probably extinct; two other stocks (pink salmon and spring Chinook) are nearly so (Brenkman et al., 2008). The ecological effects of the absence of anadromous fish in the watershed above the lower dam are profound (Gende et al., 2002; Duda et al., 2008). Spawning runs before the dams were built carried vast amounts of marine-derived nutrients into the upper reaches of the watershed where they provided vital constituents of food webs and nutrient pathways that permeated throughout the entire ecosystem (Munn et al., 1996, 1999; Naiman and Decamps, 1997; Naiman et al., 2000; Nilsson and Berggren, 2000; Morley et al., 2008). The reduction in habitat and nutrients are thought to have caused declines in as many as 22 species of mammals and birds (Anonymous, 1994, 1995). Among these are bald eagles, black bear, bobcat, coyote, raccoon, weasel, mink, and river otter (Duda et al., 2008). Beaver are now absent in the watershed above the lower dam; northern spotted owls have been displaced in those areas of the Elwha watershed below 610 m by barred owls (Gremel, 2005). In addition, grazing habitats have been inundated, greatly reducing sheltered areas for wildlife, such as Roosevelt elk and black-tailed deer (Duda et al., 2008).
The dams and reservoirs have also radically affected the size and distribution of sediments in the lower Elwha and in the near-shore marine environment (Anonymous, 1995; Scharf, 1998; Randle et al., 2003; Morley et al., 2008). The middle and lower reaches of the river (between the two dams and below the lower dam, respectively) have been starved of small-size sediments, now trapped in the reservoirs. Approximately 4 million cubic meters of sediments have accumulated in Lake Aldwell, and 13.8 million cubic meters in Lake Mills (U.S. Bureau of Reclamation, 1995, 1996a). Because of the reduction in small sediments in the lower part of the river, the greatly reduced spawning habitat has been further degraded. 
The river's estuary has also been subjected to reduced sediment inputs and consequent erosion, as have near-shore areas along the Strait of Juan de Fuca east of the Elwha. Sediment discharge from the Elwha is thought to have been reduced by about 280,000 cubic meters annually (U.S. Bureau of Reclamation, 1996b). Intertidal and subtidal zones now consist primarily of large cobbles instead of sand. Other effects are present in the lower part of the river; for example, the interruption of normal floodplain dynamics, and a drastic reduction of large woody debris, which provides essential salmon habitat (Anonymous, 1995; Hoffman and Winter, 1996; Foster Wheeler, 2000; Pizzuto, 2002; Allaway, 2004).
Dam Removal.—As electrical power from the dams declined in importance in the last quarter of the twentieth century—by the early 1990s, the dams were providing only 38% of the power needs of a single pulp and paper mill in Port Angeles (Anonymous, 1995)—and an appreciation of the values of a natural ecosystem on the Elwha has grown, interest in removing the dams has increased (Johnson and Graber, 2002). The questionable presence of a dam in a National Park, the impacts of the dams on salmon and other aspects of natural ecosystems, the inadequacy of mitigation of these impacts and the high cost of providing sufficient mitigation, and the relatively low value of the dams for power generation, particularly with alternative sources available, have all contributed to what is now a consensus that the dams must go (Anonymous, 1994, 1995; Allaway, 2004; Duda et al., 2008). With the funds authorized by Congress, the dams have been bought by the federal government, and planning is well underway for their removal (groundbreaking for the first water treatment facility took place on 14 September 2007, attended by both Washington State senators and Congressman Norm Dicks). Demolition is now scheduled to begin in early 2012 (Elwha Research Consortium, 2007). Current plans call for removing both dams at approximately the same time and allowing trapped sediments to wash down the river as quickly as possible. Removal will extend over at least two years, with activities suspended to allow sediments to clear when spawning fish return to the lower part of the river (Allaway, 2004).
Approximately $185 million has been authorized to pay for acquisition and removal of the dams, mitigation of impacts of dam removal on water supplies and other infrastructure, including protection for the tribal and state fish facilities, and for restoration (Anonymous, 1994, 1995). Scientific research and monitoring—beyond the limited needs for restoration (e.g., determining the size of current and future fish populations, the most effective way to re-vegetate the drained reservoirs, etc.; see Shafroth et al., 2002; Brenkman et al., 2008)—and education and public outreach are not funded under the Restoration Act (Allaway, 2004).