"The Lao government's decision to forge ahead with the Don Sahong hydropower project in southern Laos, located just 1 kilometer (0.6 miles) upstream of the core habitat for Mekong dolphins, could precipitate the extinction of the species from the Mekong River," the World Wildlife Fund said in a statement Thursday.
The dam builders' proposal to use explosives to excavate millions of tons of rock will create strong sound waves that could kill endangered Irrawaddy dolphins, which have highly sensitive hearing structures, the WWF said.
"Plans to construct the Don Sahong dam in a channel immediately upstream from these dolphins will likely hasten their disappearance from the Mekong," Chhith Sam Ath, WWF-Cambodia country director, said.
"The dam's impacts on the dolphins probably cannot be mitigated, and certainly not through the limited and vague plans outlined in the project's environmental impact assessment," he said.
The WWF said it would urge Cambodian Prime Minister Hun Sen to call for a moratorium on the dam during the Mekong River Commission's Heads of State Summit in April.
The Mekong River Irrawaddy dolphin has been listed as critically endangered on the World Conservation Union Red List of Threatened Species since 2004.