Earlier this week, Zhang Guobao, China's top energy official, said that in order for China to achieve its clean energy development targets for 2020, it must start building more big hydropower projects. At a time when much of the world is swearing off big dams because of their adverse environmental and social consequences, the announcement further exacerbates concerns about the future of the 5,400 kilometer-long Mekong River, where three dams are already in place, two more very large ones are being built and at least nine more are planned as China and countries on the lower reaches vy for the Mekong's water and the power it can produce.