The new CEO of the Mekong River Commission will face a tough test next month when the four-nation, inter-governmental body meets in Siem Reap to discuss, among other issues, the controversial Xayaburi dam project in Laos.

The MRC will decide whether to approve the proposed dam, International Rivers has said, adding that the MRC’s “own project review found that [the dam] would block fish migrations, threatening between 23 and 100 species, and affecting fisheries throughout the Mekong river basin”.

The MRC’s new CEO, Hans Guttman, was head of the its environment program from 2001 to 2007, it said in a statement yesterday.

Established in 1995, the MRC is comprised of four countries the Mekong passes through: Cambodia, Laos, Thailand and Vietnam. It was set up to be a regional mechanism to ensure that the countries consulted with one another on projects that could affect the river.

Laos is pushing for the dam to go forward, while concerns are rising in the three downstream nations about its possible effects. Cambodians are particularly susceptible to the impact dam construction would have on fish populations because they are heavily reliant on fish for food, studies have found.

The Xayaburi is the first Mekong mainstream dam to undergo the MRC’s prior consultation process and is likely to set a precedent for how future decisions are made on 11 other proposed Mekong dams, environmental groups have said.

“The future lives of many depend on governments’ willingness to say no to the Xayaburi Dam,” International Rivers said.

Surasak Glahan, a communication officer at MRC, said Guttman would be unavailable to answer questions about the proposed dam for about a week.