Flawed dam impact assessment gambles with fate of Mekong River
Located just one kilometre upstream of the Cambodia-Laos border on the Mekong River, the Don Sahong Dam if built will block the Hou Sahong channel - the only year-round channel for trans-boundary fish migration - causing permanent damage to the Mekong basin's highly productive fishery resources, which is valued at US$1.4 - US$3.9 billion per year.
WWF's review, conducted by international fish passage experts, finds the EIA riddled with problems such as inappropriate research methods, contradictory or lack of evidence and making recommendations on mitigation that have not been proven to work. Fundamental problems begin with factual errors about the proposed dam site's geography, ecology, and surrounding communities, showing an alarming lack of knowledge of the area and its context, despite having conducted the study.
“It is crucial that environmental and social impact assessments of the Don Sahong Dam are done objectively and scientifically, so that risks to people, natural resources and wildlife in the Lower Mekong are well understood and considered. This is what the EIA is supposed to do,” said Mr Chhith Sam Ath, Country Director of WWF-Cambodia. “Currently, the EIA fails to address trans-boundary concerns, critical knowledge and data gaps regarding the impact of the dam, and therefore cannot be considered acceptable as a scientific study.”
The Mekong River Commission's (MRC) Preliminary design guidance for Proposed Lower Mekong Basin Hydropower Schemes states that the project must ensure 95% of target fish species can pass through the dam’s fish passage. The EIA has not demonstrated with any evidence that the dam can achieve this requirement. Even in the unlikely event that a maximum 5% fish passage reduction is maintained, this will still represent significant annual losses to the Mekong economies that currently benefit from rich fishery resources.
“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,” Mr Chhith Sam Ath added. “The EIA recommends using a lift system to trap and transport large fish from below the dam to the other side as part of measures for allowing fish passage through the dam, but does not provide adequate studies to support its recommendations. Moreover, this has never been implemented in Southeast Asia, or in the Mekong River where the critically endangered Giant Catfish thrives, and can grow up to three metres long and weigh 300 kg.”
The related Social Impact Assessment (SIA) neglected important villages that would be impacted by the project, by not considering or consulting them. Plans for monitoring impacts to people and environment are also weak and vague, and are unlikely to provide timely warning for problems. In the event that the proposed mitigation measures do not work, there is no alternative plan or failsafe.
“The EIA reveals unscientific assessments and recommendations that lack credibility. It is the responsibility of Mega First, dam developers and Mekong governments to ensure that they do not continue to develop the project based on this unscientific study,” said Mr Marc Goichot, Manager of Sustainable Hydropower & River Basin Management with WWF Greater Mekong. “We urge stakeholders in upcoming governmental reviews and technical workshops organised by the Laos government to be rigorous in considering these issues.”
WWF calls for a suspension of the Don Sahong Dam pending completion of independent, comprehensive and scientific trans-boundary studies, with the inclusion of transparent consultation with governments, civil society and communities that would be affected by the proposed dam.