Although widely condemned by academic specialists, environmentalists and civil society groups, the Lao Government plans to proceed with construction of the Don Sahong dam. The proposed dam, discussed in an Interpreter post in November, appeared to be largely escaping official criticism from the other members of the Mekong River Commission (MRC): Cambodia, Thailand and Laos.

It was notable that representatives of the Cambodian National Mekong Committee were not repeating their earlier (2009) criticisms of this dam which, if constructed, would have a major impact on the fish stocks that are so important for the Cambodian population's diet. It is estimated that fish from the Mekong and its tributaries account for 80% of the Cambodian population's annual animal protein intake.

However, at a meeting of the MRC held in Vientiane on 16 January, the representatives of Cambodia, Thailand and Vietnam made clear their concerns about Don Sahong and their wish to see the proposal to construct the dam referred the the MRC Council for ministerial consideration. 

Multiple issues are involved in this development. Of first importance is the likely environmental impact of the proposed dam, since it will be located on the one channel through which migratory fish can pass through the Khone Falls region throughout the year. This is an issue that has been widely discussed and on which there is substantial agreement on the basis that there is no way to mitigate the barrier to fish migration that constructing the dam would involve. This has importance for fish catches both above and below the Khone Falls.

Linked to this is the debate as to whether or not the Don Sahong is being built on the mainstream of the Mekong. The Lao government and representatives speaking for the Malaysian firm contracted to build the dam argue that the dam's site is not on the river's mainstream and that alternative channels can be found for fish migration. This may appear to be an 'angels on the head of a pin' issue, but it does have relevance under the terms of the 1995 Mekong Agreement. Under that agreement member states are required to submit dam proposals to the Ministerial Council if the intention is to build on the mainstream of the river. Dams on tributaries are only subject to the requirement that notification should be given of their construction. Don Sahong has always been assumed to be a mainstream dam and the fact that Laos is now arguing the alternative case seems to have little validity. To state, as the Lao representatives now do, that because the amount of water that flows past the Don Sahong site is only 15% of the total flow over the Khone Falls smacks of casuistry. In any case, the Lao government is holding firm to its view

Depressingly for those, including the present writer, who hold concerns about developments that will seriously diminish fish stocks in the river, it seems all too likely that referral of the Don Sahong dam to the MRC Ministerial Council will not, in the long run, prevent the dam being built.

Under the terms of the 1995 Mekong Agreement,  the MRC cannot prevent member parties from buildings dams on the mainstream of the river if they are really determined to do so. Laos has already made this fact clear with its decision taken in 2012 to proceed with the construction of a dam at Xayaburi against the wishes of Cambodia and Vietnam. Placed against the relatively small hydroelectric generating capacity of the proposed dam (240 MW), the ultimate costs in the Lower Mekong Basin of finding alternatives to wild fish are substantial, as this recent academic survey has shown

Just as was the case with the Xayaburi dam, the prospect that Don Sahong will indeed be built raises concerns that a domino effect will take place and lead to other dams being built on the mainstream of the Mekong, most probably in Laos. Should this 'race to the bottom' take place the ultimate costs to food security would be serious indeed. 

 Photo by Flickr user International Rivers.