It is important to keep in mind that dams, by their placement alone, are inherently situated in culture, history, geography, geology, language, and discourse. Each dam has its own unique relationship with its context. We have chosen to situate our research at Bonneville Lock and Dam on the Columbia River. Bonneville is a 60-meter-high run-of-the-river dam located 40 miles east of Portland, Oregon. Opened in 1938, the Bonneville Dam is among the generation of high-profile federal hydropower projects that dominated the major rivers of the west through the 1930s and 1940s. Today, Bonneville Dam is used for hydropower generation through Bonneville Power Administration, recreation at the visitor’s center and local waterways, and fish migration through fish ladders that aid salmon and steelhead in their migration upstream to spawn (Bonneville Lock and Dam 2013).
The entire region of the Pacific Northwest, including Portland and the Bonneville Dam, is situated along the Cascadia Subduction Zone, a plate boundary prone to large earthquakes. Because the most recent Cascadia earthquake occurred in 1700 and severity of the Pacific Rim earthquake was not realized until the 1980’s, the infrastructure of Portland was not built with knowledge and policy that reflects the seismic character of its location (Ashford 2015). Even since the development of the Oregon Resilience Plan(Oregon Seismic Safety Policy Advisory Commission 2013), public agencies, private businesses and individuals are not adequately prepared for the impending earthquake. Because of the uncertainty around when, where, and how large to earthquake might be, it’s difficult to incite the cultural, legal, and social impetus needed to inspire a culture of preparedness (Ashford 2015).
The Bonneville Dam has a unique geologic placement that places it in a potentially hazardous area. The Columbia River Gorge has been the site of a number of historic landslides, including the great Bonneville Landslide of the 15th Century which actually blocked the course of the Columbia River for a time at the location of the Bridge of the Gods (Pierson 2014).
From our research, we have found no evidence that the Bonneville Dam is at risk of complete failure due to the seismic hazard of the Cascadia Subduction Zone. In fact, because Bonneville is under 100 feet and a run of the river dam which holds no significant reservoir behind it, the risks of dam failure are relatively low (CSADD 2010). Even the tsunami will likely have no effect on a dam so far upstream (Strauth 2015). This brings us to an important distinction between risk and hazard. Hazard is a potential source of harm. In this case, the earthquake is a hazard and the dam failure is a hazard. Risk in the other hand describes the likelihood that a being or object be harmed by the hazard. Risk, thus, is describes where events intersect with people or infrastructure and create problems.
While predictions have been made about the effects an earthquake will have on the power the Bonneville dam supplies, little has been done to see how the actual dam will perform in a quake event. There is very little research published about the seismic hazards and risks at dams in the Pacific Northwest. We could not find an emergency action plan. The significance and need to assess the hazard and risk of the Bonneville dam can be summarized as: “The impact of earthquakes on public safety and the national economy can be reduced through improvement of the built- environment to resist earthquake effects such as ground shaking. Reduction of the economic impact on individuals and the nation can also be reduced by additional means such as earthquake insurance” (USGS 2016).
While we don’t possess the technical expertise to assess the Bonneville Dam for specific pathways of failure, we intend to explore potential locations of change in the infrastructure, landscape, and function of the Bonneville Dam as a result of a high magnitude earthquake. We ask: How might the function of the Bonneville Dam be altered in the event of a Cascadia earthquake? The structure of the Bonneville Dam is not likely to completely fail in the event of an 9.0 Cascadia quake event. However, certain aspects of the function, including its salmon rehabilitation. efforts, recreation opportunities, and energy production may be at risk or subject to change in the face of the impending earthquake. This study has the potential to provide insight into how human structures and the institutions that manage them might survive disasters through physical, functional, and symbolic adaptation.