The Mekong River Commission, a regional management forum, said the countries would approach Japan and international agencies to further study the impacts of the proposed $3.5 billion Xayaburi dam.
The commission’s decisions are not binding, and there are signs that Laos is starting preparations for the project.
In what has become Southeast Asia’s biggest environmental battle, opponents say the dam in central Laos would open the door for a building spree of as many as 10 other dams on the 34,900-kilometer-long river in Laos and Cambodia, degrading its fragile ecology and affecting the livelihoods of millions of residents.
But Laos, an impoverished country eager to gain revenue from hydroelectric power, has been pushing for its construction despite strong opposition from Vietnam, its longtime communist ally, environmental groups and villagers along the river.
Thailand, which has planned to buy 95 percent of the electricity from Xayaburi, and Cambodia, which hosted the forum in the town of Siem Reap, are the other members of the regulatory commission.
A press release from the commission did not give a time frame for the studies or details of the involvement by Japan and international development agencies.
It said Thursday’s outcome demonstrated a spirit of compromise, with the countries seeking to promote economic development without sacrificing the ecology or people’s livelihoods.
“The Mekong governments have made the right decision today,” said Pianporn Deetes of the US-based environmental group International Rivers. “With so much at stake, more time is desperately needed so that an informed, participatory and responsible decision can be made.” She said that proceeding on the dam “would be a tragedy for the Mekong River.” Despite Thursday’s move, Laos has strongly indicated in recent months that it will eventually erect the dam, confident that sooner or later it can convince opponents that it has taken measures that would mitigate its impact. An approach road and other dam-related facilities are already being built.
But landlocked Laos, heavily dependent on its neighbors and international aid, has to tread carefully, even though it could proceed on its own with the construction under Mekong River Commission rules.
During a similar commission meeting in April, the four countries decided to defer a decision. Vietnam has urged at least a 10-year moratorium on all mainstream dams on the Mekong.
The Xayaburi dam would cut across a stretch of the river flanked by forested hills, cliffs and hamlets where ethnic minority groups reside, forcing the resettlement of up to 2,100 villagers and impacting tens of thousands of others.
Environmentalists say such a dam would also disrupt fish migrations, block nutrients for downstream farming and even foul Vietnam’s rice bowl by slowing the river’s speed and allowing saltwater to creep into the Mekong River Delta.
China has placed three dams across the upper reaches of the Mekong and more are planned, but otherwise the mainstream flows free.
