Why Dam Removal Is An Important Issue For All Watersheds

I happened across a National Geographic article from mid-May that celebrated the removal of 65 dams on American rivers in 2012. I was surprised to read that 9 of those dam removals occurred in Massachusetts, because I have associated major dam removal projects and controversy with the Pacific Northwest, not New England. Many of the dams removed, such as the Bartlett Rod Shop Co. Dam on Amethyst Brook in Massachusetts, were obsolete and posed a public safety threat. In these cases, I want to applaud the agencies responsible for successfully and safely accomplishing a step toward river and watershed restoration in their communities. However, I think that dam removal is an important policy issue for all American river watersheds because our nation's dams are aging, and while the many long term benefits of removal have been discussed, little is known about the negative effects of removal on the surrounding ecosystem. 

It is not surprising that the general public perceives dams as permanent structures. After all, it is difficult to imagine that the Hoover Dam could be anything but eternal in all its concrete enormity. However, the function of dams is to impede water, the universal solvent. Therefore, dams by definition have an expiration date; their structural integrity breaks down over time as a result of interacting with water. As these structures approach this date, agencies responsible for dam management are faced with the challenge of enforcing regulations and policies to ensure that the safety and viability of surrounding communities and ecosystems are maintained. Dam removal is a management tool to this end.

Removal of the Glines Canyon Dam on the Elwha River in Washington State
Courtesy of http://www.realscience.us/2012/07/12/fish-swim-free-in-elwha-after-dam-comes-down/

However, the practice of dam removal is too poorly understood to be considered the best or only option for the management of aging dams. Of the 75,000 dams that have been constructed on American rivers, only 500 have been removed (Gregory, 2005). Until the ecological effects of dam removal are better documented and analyzed, alternative management strategies must be equally considered. These alternatives include structural repair, changes to dam operation, or even no action at all (Hart, 2002). Although repairing or altering dams is often considered costly, these strategies should not always be replaced by dam removal. The concept of taking no action at all may seem negligent, but dams and their potential removal vary greatly in circumstance and risk. These circumstances are determined by the infinite physical parameters governing watershed systems, and so the risk a dam poses must be considered on a case‐by‐case basis. Instead of encouraging a political climate that either condemns or blindly accepts dam removal as a management strategy, relevant agencies and governments should work to develop policies that will outline systematic decision-­‐making schemes, as well as encourage scientific understanding of the subject by setting standards for analysis and study.

Mass transport of sediment is a consequence of large dam removals, and one of many concerns  biologists have about dam removal, since the sediment contributes to turbidity and can ruin spawning grounds for anadromous species of fish. The above photo shows the sediment plume into the Juan de Fuca Strait following the removal of the Glines Canyon Dam.

Source: Tom Roorda, http://www.washington.edu/news/2013/03/07/tracking-sediments-fate-in-largest-ever-dam-removal/

During the first half of the 20th century, the United States experienced an era of dam construction in response to increasing demands for energy and water resources fueled by population growth. Legislation such as the Flood Control Act that was passed by Congress in 1927 contributed to a political and social climate that made dam construction an ideal and worthwhile investment (Doyle, 2003). Indeed, dams and their reservoirs successfully provided a variety of services crucial to the nation’s development, such as hydroelectric power generation, irrigation for agriculture, flood control, water storage, and recreation. However, the physical nature of dams interacting with water flows over time diminishes their economic viability and functionality. These structures have a life span between 50-­100 years (Gosnell, 2010), and the choice between relicensing, decommissioning, upgrading, or removing aging dams is becoming crucial to successful watershed management. Furthermore, the political and social climate has begun to change again. Legislation such as the Endangered Species Act puts more pressure on agencies involved in dam management, such as the Federal Energy Regulatory Commission, to force dam owners applying for license renewal to comply with stricter regulations by implementing expensive mitigation strategies.

Unfortunately, the practice of dam removal brings uncertainties into the picture due to its relatively rapid emergence in water management. Over 500 dams were removed in the United States during the past 20 years alone (Doyle, 2003). Although most of these dams were categorized as “small” (being less than 15 meters in height), little is known about the effects of removal. It would be unwise to simply assume that dam removal always reverses the many negative ecologic consequences dams themselves have caused in watersheds (Stanley, 2003). Instead, removal should be considered a management tool to be implemented only when careful analysis of each specific site is performed.

Sources:

Doyle, Martin W., Jon M. Harbor, and Emily H. Stanley. "Toward Policies and Decision- Making for Dam Removal." Environmental Management 31.4 (2003): 453-65. Web. 10 Feb.

2013.

Gosnell, Hannah, and Erin C. Kelly. "Peace on the River? Social-ecological Restoration and Large Dam Removal in the Klamath Basin, USA." Water Alternatives 3.2 (2010): 361-83. Directory of Open Access Journals. Web. 10 Feb. 2013.

Gregory, Stan, Hiram Li, and Judy Li. "The Conceptual Basis for Ecological Responses to Dam Removal." BioScience 52.8 (2002): 713. Web. 25 Mar. 2013.

Hart, David D., Thomas E. Johnson, Karen L. Bushaw-Newton, Richard J. Horwitz, Angela

T. Bednarek, Donald F. Charles, Daniel A. Kreeger, and David J. Velinsky. "Dam Removal: Challenges and Opportunities for Ecological Research and River Restoration." BioScience 52.8 (2002): 669. Web. 10 Feb. 2013.

Stanley, Emily H., and Martin W. Doyle. "Trading Off: The Ecological Effects of Dam Removal." Frontiers in Ecology and the Environment 1.1 (2003): 15. Web. 10 Feb. 2013.