The Lao government believes that the Don Sahong dam, which is to be built on a stretch of the Mekong River just 1 km from the Cambodian border, will have no significant consequences for fisheries in downriver countries, according to documents released Wednesday by the Mekong River Commission.
According to a cumulative impact assessment—which was carried out by Laos and attempts to measure the dam’s impact in the region—the impact of the dam will be “insignificant.”
“[The dam] will not have significant cumulative impacts on the Mekong River flows, sediment transport, fish migration, or fisheries,” according to the report, dated January 2013.
The report notes that Mekong fisheries could be affected but only if the project is poorly managed.
“If poorly managed, this project would exacerbate the existing natural ‘choke’ on fish migration at this location in the system,” the report says.
However, the dam’s placement in only one of 17 channels, which allows fish to access other migration routes on the Mekong, the report continues.
The dam’s environmental impact assessment (EIA) report also says the project does not have measures in place to mitigate the alteration of river flow and sediments, as they will not be affected by the dam.
“As the [Don Sahong dam] will not significantly increase any of these threats, no mitigation or management actions have been proposed for them by this project,” the EIA report states, adding that the region’s fisheries face more of a threat from over-fishing than migration routes blocked by the dam.
Ian Baird, assistant professor of geography at the University of Wisconsin-Madison—and one of the foremost scientists of Laos’ Khone Falls fisheries who has produced numerous scientific articles on that area’s fish migration and biodiversity—said in an email that it was false for the report to infer that the dam would not impact downstream countries.
“[I]t is completely inaccurate to claim that the dam would not have any impact on Cambodia, Vietnam or Thailand. It will—the only question is how much,” he said. “The stakes are simply too high to test out these unproven measures on such an important resource for the whole region.”
“Everything is so far unproven, and there is no guarantee that any of the parts of the mitigation plan will be successful,” Mr. Baird said. “The authors of the studies admit as much, but they do not offer to be responsible for miscalculations.”