Residents of northern Chile are appealing that a tailings dam project, which is now almost halfway complete, be halted. Once completed, it would be the third largest tailings dam in the world and would eventually hold 1,700 million tonnes of tailings, mainly slurry laden with toxic waste leftover from processed copper generated by the Pelambres mine.

Environmentalists and local residential groups say that the tailings dam would lead to water contamination and other kinds of environmental degradation. Besides, the project threatens ancient indigenous petroglyphs in the Pupio river basin with submergence. The community activists also remain worried about the risk from the tailings dam during an earthquake. The project has been facing massive protests since 1997, when around 98 per cent of the residents of Caimanes, a nearby town, had voted against it in a plebiscite. But the mining company managed to secure the project's approval in April 2004.