A conservation group has said its recent trip to Laos revealed that construction on a controversial hydropower dam decried by neighbouring Mekong countries is already under way.

International Rivers representatives visiting the proposed site of the 260-megawatt Don Sahong Hydropower Project earlier this month say they found that developers had already begun building a bridge to create an access route for dam construction.

Tep Vannara, executive director of NGO Forum and an outspoken critic of the dam, yesterday said news of the construction was “disappointing, but not surprising”.

“The millions of people living on the Mekong will be adversely affected by the decisions they are making,” he said. “The Mekong countries have already told [developers] that they need to wait for more scientific study to fully understand the consequences of the project on this shared river.”

At an international summit in April, Cambodia, Thailand and Vietnam called on Laos to stop construction on all mainstream Mekong projects for 10 years while more scientific evidence and agreements on the waterways could be undertaken.

Developers of the Don Sahong have disputed the classification of the dam as a “mainstream project” as it will lie on a tributary rather than stretch across the full river. But opponents maintain that with the effects the dam will have on the waterway and the migrating fish populations, it should go through a consultation process with potentially affected downstream countries such as Cambodia.

International Rivers’ discovery of construction at the dam site comes just a week before the four Lower Mekong countries will gather in Bangkok, in part to discuss whether the Don Sahong merits deliberation at a higher level within the intergovernmental Mekong River Commission.

In a statement issued yesterday, World Wildlife Fund requested that during the upcoming meeting, countries preserve regional food security and biodiversity over potentially irreversibly damaging hydropower dams.

The conservation NGO WWF has in the past called out the Don Sahong’s developers for not fully considering the project’s downstream environmental impact or properly informing the soon to be affected communities.

“The clock is ticking to stop [the] Don Sahong dam,” said Chhith Sam Ath, WWF country director for Cambodia.