A long-brewing regional debate over whether or not to build the proposed Xayaburi Dam on the Mekong River has hit boiling point.  

If there were any delusional fantasies remaining that mainstream dam building could be sustainable, the Mekong River Commission's new independent technical review of the proposed Xayaburi Dam has surely dissolved them.  

The MRC Secretariat's expert review of the Xayaburi Dam's key project documents - released a few days ago - highlights the grave environmental and social harms associated with the project, while also identifying considerable knowledge gaps that remain and require comprehensive study over the short to long-term.  

The harm caused to the Mekong River's fisheries alone will be devastating.

As the Mekong River hosts the world's largest freshwater fishery and ranks as the second most biodiverse river in the world, the dam will block an important fish migration route and forever alter the river's habitat. The review warns that as many as 23 to 100 fish species would be threatened, including the Mekong Giant Catfish and four others found in the IUCN Red List of Threatened Species. Based on the review's study of the cascade of six dams, including the Xayaburi Dam, proposed in this stretch of the river, fishery losses are estimated at around 66,000 tons per year, which is nearly half of the entire estimated yield for the country of Laos. While the exact loss associated with the Xayaburi Dam is not known, the review states that "Experience from other areas suggests that most of the loss would be associated with construction of the first dam in the cascade."  With the majority of the basin's population dependent on the river's resources, the loss would place the livelihoods of more than 450,000 people at risk. 

While the project developer's Environmental Impact Assessment (EIA) made false claims that fishery losses could be mitigated, the MRC's review on the other hand minces no words. Its experts state that transboundary impacts to fisheries will remain even if international best practice is applied to dam design and operation, as "there is no definitive solution to mitigate the lost fish production in the Xayaburi Dam area." The review also dispels the myth that reservoir fisheries may be an effective mitigation measure, by stating that there is a "misunderstanding that damming the river to create a series of run-of-the river reservoirs could increase the fishery yields."  

While this project should clearly be canceled, numerous questions remain. Will the future decision over Xayaburi reflect science and reason, or will it be based solely on politics? Will public accountability be at stake given the expressed opposition to the project during the public consultation process? How can the continuation of the decision-making process be justified given the fact that the project has failed to meet the minimal requirements set out by the MRC's Project Design Guidelines, let alone international best practice?

With so much at stake, one hopes that facts will be central to the final regional decision-making meeting scheduled for April 21st.

More information: 

• Read the MRC's Prior Consultation Project Review Report
• Read the MRC's reports on the National Consultation Meetings held on the Xayaburi Dam in Thailand, Cambodia and Vietnam.