A multi-billion dollar hydro-electric power plant on the Mekong river in Laos was officially switched on Tuesday, as drone images of dried-up downstream areas stirred fresh outcry on one of the world’s great rivers.

The Thai-owned Xayaburi dam has been a lightning rod for criticism even before construction began in 2012, with environmentalists warning of its devastating impact on the river’s fish species, sediment and water levels.

The Mekong – which rises on the Tibetan plateau and courses through China, Myanmar, Laos, Thailand, Cambodia and Vietnam – sustains tens of millions of people along its banks through fishing and transport.

But rapid development has alarmed communities along its banks, as well as conservationists who have observed shocking changes to the life-giving waterway.

Landlocked and impoverished Laos has set its sights on becoming “the battery of Asia,” with 44 operating hydro plants and 46 more under construction, according to the monitor International Rivers.

CKPower, a subsidiary of the builder and majority shareholder Ch Kanchang, went ahead with the $4.47 billion construction of the 1,285-megawatt project despite criticism.

“Xayaburi Hydroelectric Power Plant is ready to commence,” CKPower said in a statement Tuesday.

Developers plastered Thai newspapers with advertising touting the Xayaburi dam as a “fish friendly power plant” and the “blueprint of renewable energy.”

But drone footage taken Monday downstream in Thailand’s Nong Khai province suggested a different story, as plummeting water levels exposed vast areas of parched river bed.

Pianporn Deetes, of International Rivers, said some parts of the Mekong in that region had experienced worrying drops in water levels since July coinciding with Xayaburi’s trial operations.

“They have monopolized the future of the Mekong’s ecosystems and of the river basin’s population,” she told AFP, adding it was difficult to fully evaluate because of a lack of information.

Contacted by AFP, the company did not immediately respond to requests for comment.

Thailand is supposed to buy almost all of the electricity generated by Xayaburi.

Still, a network of residents from seven provinces in Thailand issued an “urgent” plea Monday for the Thai government to mitigate the environmental impact of the Mekong dams.

“Today is the last day we will have the same life along the lower Mekong region,” they said in a statement.

The perils of the dam-building frenzy in Laos were laid bare last year when a massive hydro dam project collapsed in the south of the country, killing dozens.

AFP