As I write this article, the largest dam removal project in the world is underway on the Elwha River in Washington State. Over the next three years, 18 million cubic yards of sediment and 48,600 acre-feet of water—equal to over 2 billion cubic square feet, enough water to “flood Safeco Ballpark in Seattle to the height of a 130-story skyscraper”—will be drained from behind Elwha’s two reservoirs.1 The removal of the Elwha Dam and the Glines Canyon Dam is the culmination of years of effort on the part of environmentalists, government officials, and leaders of the Elwha Klwha tribal community. Many have heralded the removal of the dam as the beginning of a new era of dam decommissioning in the United States. Whether or not this prediction pans out will depend, in part, on the rulings the United States Department of the Interior is slated to make in early 2012 on a massive dam project in Alaska.
Damming of the Elwah River and its Effects on Fish Populations
The Elwha River, a 45-mile long stretch of turquoise cutting through the Olympic Peninsula of Washington, has a rich history. The River was inhabited by the Elwha Klallam Tribe prior to the arrival of Europeans in the late 1700s. Members of the Lower Elwha Klallam Tribe tell reporters that there was once a time when the river was “so chock-full of glistening flesh that one could practically walk across on the bodies of writhing fish.”3 All of that changed in the early 1900s when Olympic Power erected the Elwha and the Glines Canyon dams, in 1910 and 1927 respectively. The prevailing social myths of the day, which perpetrated the idea that “hydropower was cheap, clean, and beneficial for everyone,” allowed Olympic Power to feel justified to violate Washington State Law.4 For the Olympic Power Company, the need to produce hydropower for a local power mill superseded the interests of the Elwha Klallam Tribe.5
Immediately after the dams were built it became clear that they had decimated the huge salmon runs the Elwha had once sustained. Although the 1938 creation of Olympic National Park preserved the upper watershed, the Elwha and Glines Canyon dams had already blocked all but the lower 4.9 miles to upstream salmon migration.6 Dams in the early 1900s were often built without the fishladders that later became mandatory. Thus these dams serve as completely impenetrable barriers to fish migrations.7 The dams have also had other effects over the last 90 years. For instance, only in the last few decades have scientists begun to catalog how sediment deprivation has impacted the Pacific Ocean and its fisheries.8
In addition to the environmental impacts of the Elwha River dams, the safety risks of the dams also played a role in their eventual decommissioning. Once dams get to be half a century old, they begin to degenerate, which means that concrete begins to crumble, earthworks erode and seep, spillway gates rust, and sediments clog reservoirs. As maintenance and liability costs rise, economic returns drop. And, in the worst case scenario, aging dams could fail and cause catastrophic flooding downstream.9
pubs.usgs.gov
Undamming The Elwha River
The removal of the Elwha and Glines Canyon dams was proposed as far back as the 1960s and 70s. During this time, both dams were undergoing Federal Energy Regulatory Commission (FERC) licensing procedures. Members of the public raised concerns to the Commission about the environmental impacts of the dam, and questioned whether the dams should be allowed to operate in a National Park. After decades of lengthy and controversial disputes, congress passed the Elwha River Ecosystem and Fisheries Restoration Act in 1992. The act mandated that the Department of the Interior (DOI) study alternatives to the dam that would restore the Elwha River ecosystem.
In 1994, the DOI determined that in order to fully restore the River, it would be necessary to remove both dams. Thus, the federal government purchased the dams in the year 2000.11 However, even with this support from the government, it took over a decade to begin the actual removal process. Forty-three projects designed to prepare the River and the region for the effects of the dams’ removal had to be completed prior to demolition. For example, new water treatment plants had to be built to handle an increased volume of sediment, and levies had to be improved to protect properties along the River. The National Parks Conservation Association and other groups had to raise an estimated $351 million to pay for the entire removal process.12
The teardown finally began on September 27, 2011, and it should take about three years to complete. Although it would be convenient if the dams could be blasted away with dynamite, engineers are fearful that a sudden surge could cause an enormous sediment slide. As Olympic Park spokesman Dave Reynolds has noted, this project is “not just the biggest dam removal in history, but also the biggest controlled release of sediment.” In addition, officials want to be extra careful given that the City of Port Angeles draws its drinking water from the Elwha River, and that the River supports a fish hatchery and a low-lying Indian reservation.13
The removal of both Elwha dams will open 70 miles of prime spawning habitat for all five species of Pacific salmon. Although the recolonization process will be gradual, eventually the salmon population in the area is predicted to grow from 3,000 to almost 400,000.14 Over the next 30 years the Elwha will re-establish a flow similar to what it was historically. Biologists point out that the return of the salmon will help lead to the recovery of more than 130 species of plants and animals that have “been deprived of a vital food and nutrient source for nearly a century.” 15
Future of Dams in the United States
The results of the Elwha River project will allow scientists and politicians to see how easy or how hard it is to restore a river, and will hopefully inspire more dam removals in the future. Currently, more dams in the United States are being considered for removal than are being built. Almost 200 dams have been torn down in the last six years alone. Indeed, in 1995, Daniel Beard, head of the US Bureau of Reclamation, the nation’s main constructor of dams, declared the US dam-building era over. He cited growing environmental concerns.16 Perhaps there is a growing belief that the benefits of maintaining a great number of aging dams in the US are outweighed by the benefits realized by their removal?!
Mr. Beard’s assertion that the US dam-building era is over will be tested early next year when US Department of the Interior makes a decision about the massive dam project to be installed in Alaska. Alaskan authorities plan on filing an application for a $4.5 billion project to build a 213 meter megadam (to generate 600-megawatts of power) on the Susitna, one of the county’s last remaining wild rivers. If the project is approved it will be the country’s first hydroelectric megadam for 40 years and its fifth tallest. It appears that after years in the “environmental doghouse,” large dams are now being promoted as one of the best sources of low-carbon energy. The Susitna dam was first proposed in the 1970s, but at that time it was dropped due to its large cost and predicted negative environmental consequences. Two years ago, then-governor Sarah Palin revived the scheme. Environmentalists argue that the US Department of the Interior to should continue to decommission dams, not build more. They point to studies that indicate that the Susitna’s 62-kilometre reservoir will “flood a migration route used by pregnant caribou and the grizzly bears that prey on them, and disrupt a major run for Coho and sockeye salmon,” and urge the State to tap its abundant tidal, geothermal and wind power instead.17
The lessons learned during the Elwha dams’ removal will be valuable for making decisions about future dam projects like the one proposed for the Susitna. The future of dams in the US is unclear, but this country is not alone in the debate. Here are some additional articles dealing with the effects of dams:
http://www.wordpress-837916-4114959.cloudwaysapps.com/GreeniacsArticles/Energy/Three-Gorges-Dam.html
