The US$ 3.5 billion, 1.260-megawatt hydroelectric dam project is slated for a remote region of northern Laos, and would force the resettlement of up 2,100 villagers and affect tens of thousands of people. A Thai firm would build the dam, and Thailand would be the main beneficiary.
The summit in Vientiane on 19 April should seal the fate of the project, which could get the green light, get the axe or be temporarily suspended waiting for the conclusions of an environmental impact study.
Opponents of the project say it would set a precedent and allow the construction of ten more dams on the lower Mekong.
Local officials and environmental experts warn that three dams build up river, in Chinese territory, have already taken a heavy toll on the river’s ecosystem. The “Xayaburi dam will bring more suffering,” they said.
Environmentalists argue that such a dam would 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. Hanoi is in fact opposed to the project and for the first time has taken on Laos’ Communist government.
Last month, 263 NGOs from 51 countries sent letters to the governments of Laos and Thailand urging the project be shelved.
However, Laos in February said that the Xayaburi dam would be the "first environmentally friendly hydroelectric project on the Mekong" and that it would "not have any significant impact on the Mekong mainstream."
Scientists have called for its construction to be delayed for 10 years until more research is conducted.
A study by the Mekong River Commission (MRC) released in February warned that dams could reduce the fishery by 300,000 tonnes a year, with serious consequences for a million people, especially in Cambodia, who depend on fishing.
It too recommended a ten-year moratorium to better study the consequences of the project.
About 65 million people live along the Mekong River, which starts on the Tibetan plateau and flows through China’s Yunnan province before making its way to Myanmar, Thailand, Laos, Cambodia and Vietnam, which all depend on it economically.
The value of the fishery and fish farming has been estimated at around US$ 3 billion a year.
Now the 4,880-kilometre waterway, considered to be the second most bio-diverse river in the world, is threatened by hydroelectric dam projects, like the Xayaburi dam, which Laos has presented to the MRC.