With a sense that the story is becoming something like 'The Perils of Pauline', the Xayaburi dam story rolls on. The fact that the issue has become tortuously prolonged should not detract from the very serious issues involved: environmental threats to the Mekong leading to the major loss of fish supplies and diminishing of sediment flow, and a falling out between the countries of the Lower Mekong Basin.

Separately, a new research report published in the Proceedings of the National Academy of Sciences suggests dams built on Mekong tributaries could post a greater threat to the river's current role as a bounteous source of fish than dams on the mainstream.

Although Lao Government ministers insist they are, for the moment, abiding by their commitment not to proceed with construction of a controversial dam at Xayaburi on the mainstream of the Mekong River between Luang Prabang and Vientiane, as agreed with their Mekong River Commission partners (Cambodia, Thailand and Vietnam), they are concurrently speaking as if the project will ultimately go ahead.

Indeed, this latest statement from Lao Deputy Minister for Energy Viraphonh Viravong on 1 July seems to take matters further towards a determination to build the dam than was evident when this issue was last reviewed on The Interpreter.

He said research is continuing in relation to means to allow fish to pass through the dam and to permit the flow of sediment down the river. That this suggests a firm conviction that the dam will eventually be built is bolstered by the fact that the Thai company contracted to build the dam, CH Karnchong, is pressing ahead with major preliminary work at the site.

For the moment, neither Vietnam nor Cambodia have reacted to this latest Lao statement, but their opposition is clear. Just what measures they might take to prevent or delay the project remain unclear.

Meanwhile, a major research report that has so far received little media attention suggests that there should be much more concern about dams being built or planned for the Mekong's tributaries than has been the case up to now.

Reported in a March issue of Nature, the report from Stanford argues that the 27 dams currently planned on tributaries could result in 'catastrophic' loss of up to 51% of fish productivity. In particular, it condemns the plans for the Lower Se San dam in northeastern Cambodia, which on its own could lead to a fall of over 9% of current fish production. Strikingly, this a dam that has the vocal support of Prime Minister Hun Sen of Cambodia, who had denied that building the dam would affect fish stocks.