The contentious politics of hydropower dam impact assessments in the Mekong River basin

Since the 1990s, many large hydropower dams have been built in the Mekong River Basin. There has been considerable concern about resettlement and compensation linked to reservoir flooding, as well as the impacts of dams on wild-capture fisheries, riparian livelihoods, and aquatic biodiversity and ecosystems. Anti-dam activists in the Mekong Basin have contested these impacts by claiming that dam impact assessments limit the spatial scale of recognized impact areas in order to reduce both the political backlash against projects and the costs of dam development. In this article, we consider the contentious politics of hydropower dam impact assessments in order to understand how the spatial strategies of anti-dam activists influence the recognized scale of dam impacts. We analyze three of the most contested hydropower projects in the Mekong River Basin: the operational Pak Mun dam in northeastern Thailand, the recently completed Lower Sesan 2 dam in northeastern Cambodia, and the planned Sambor dam on the mainstream Mekong River in Cambodia. We argue that the recognized scale of impacts is in part an outcome of anti-dam activists’ different spatial imaginaries and associated scale frames—along with those of state actors, business interests, and project consultants—that inform activist strategies for mobilizing geographically dispersed people to make claims about dam impacts. Although activists have sometimes challenged the spatial extent of project impact assessments, they have also sometimes inadvertently adopted strategies to contest dams that have reproduced project scale frames favorable to dam proponents.