The Mekong River Commission will make a decision at the end of this month whether the construction of a controversial dam in Laos will go ahead.

The $3.5 billion Xayaburi dam is one of 11 planned for the lower Mekong River and would generate 1,260 megawatts of electricity, 95% of which is expected to be bought by Thailand.

However, strategic environmental assessment reports warn that the dam would harm the river’s ecosystem and put some 41 species of fish at risk of extinction, including the Mekong giant catfish, by blocking fish migration routes.

Cambodia and Vietnam, who have the most to lose if the dam project moves forward, have joined the choir of environmentalists, claiming that some 40 million people rely on the river’s fish for their protein intake.

The Mekong River, one of the world’s most pristine large rivers supports a remarkably diverse and productive freshwater ecosytem, second only to the Amazon basin in terms of biodiversity.

Despite the concerns, energy-starved Laos is still pressing for construction.

The Vientiane-based MRC has responsibility for final approval for construction after determining the dam’s environmental and ecological impact.