The environmental impact assessment (EIA) that will allow for the construction of the controversial Don Sahong Dam in southern Laos, just 1.5 km from the Cambodian border, was sloppy, used inappropriate methodology, and was often based on assumptions, environmental watchdog WWF said in its own research published Monday.
The impact assessment, conducted by scientists working for Mega First Berhad, the Malaysian company in charge of constructing the 256-mw dam on the Don Sahong channel of the Mekong River, was picked apart by three international, WWF-contracted scientists who found that the assessment was not “acceptable as a scientific study.”
Overall, said Chhit Sam Ath, WWF country director, the assessment’s claims were not supported by scientific evidence.
“The EIA claims that the Don Sahong Dam will not have significant impacts on fisheries, but does not provide scientific evidence to support its speculation,” he said in a statement.
Representatives for Mega First have claimed that instead of blocking fish migration, the dam would in fact improve connectivity through fish passages.
The WWF research, however, raises a total of 25 points in which the EIA was based on assumptions or factual errors.
Some of the EIA’s proposed mitigation measures do not make sense, such as installing electric fences to redirect fish used to migrating through the Don Sahong channel, according to WWF.
“The suggestion that electric fences could potentially keep fish from the area seems not well thought out. Differences in amperage, amplitude and frequency of electric currents in water are needed to guide, attract or repel fish of different sizes,” the researchers hired by WWF wrote.
Fish in the Mekong, such as the critically endangered Giant Mekong Catfish and Giant Freshwater Stingray, can weigh up to 300 kg and 600 kg respectively.
Unless there was scientific evidence to prove that proposed fish passages would allow for migratory fish—about 85 percent of all Mekong fish species—to continue to migrate up and downstream year-round, the Don Sahong should not be built, said Marc Goichot, manager of sustainable hydropower and river basin management at WWF Greater Mekong.
“It is the responsibility of Mega First, dam developers and Mekong government to ensure that they do not continue to develop the project based on this unscientific study,” Mr. Goichot said in a statement.