A Thai court decision yesterday may throw a wrench into the works of a mainstream hydropower dam loudly opposed by neighbouring countries.

Agreeing to what NGOs have called an “unprecedented trial”, the Supreme Administrative Court of Thailand accepted a lawsuit that villagers filed in the hope of seeing the cancellation of utility company Electricity Authority of Thailand’s agreement to buy almost all the power generated by Laos’s 1,285-megawatt Xayaburi Dam.

The $3.8 billion project, which the Post reported in March as being already 30 per cent complete, is the first of Laos’s nine planned mainstream projects. Conservation groups say the Thai bank-funded Xayaburi will cause irrevocable damage to Mekong fish populations, and will drastically impact the 60 million people depending on the waterway, including those in downstream Cambodia.

Last month, the Cambodian Senate lent support to the villagers’ case by also demanding Thailand cancel the purchasing agreement. The letter calls Xayaburi “the greatest trans-boundary threat to date to food security, sustainable development and regional cooperation in the lower Mekong River”.

“By investing in the Xayaburi, state authorities are failing to comply with the Thai constitution including holding proper consultations with the affected people,” Pianporn Deetes, a coordinator at International Rivers, said.

Piaporn added that activists hope the “unprecedented” trial will set a new standard for development along the region’s shared waters.

“We hope dam developers in the future will be more mindful and conduct the necessary impact assessments before starting to build,” she said.

The court order comes just two days before the four Lower Mekong countries meet in Bangkok, where they will consider another controversial Lao dam project, the Don Sahong.

While much smaller than the Xayaburi, the 280-megawatt dam could have enormous repercussions for Cambodia, which lies just 2 kilometres south. Though NGOs have previously threatened to sue the Don Sahong’s developers, they would have to take the case to international courts.

“It would not be the same [as in Thailand]; Cambodia doesn’t have the same laws or type of investment in the Don Sahong,” said Meach Mean, coordinator of 3S Rivers Protection Network. “But it has got us thinking about what could happen with Cambodian dams, like the Lower Sesan II,” he said.