Laos has given approval to the hugely-controversial $3.5 billion Xayaburi Dam on the Mekong River, reports the BBC. The massive dam, which would provide 95 percent of its energy production to Thailand, has been criticized for anticipated impacts on the river's fish populations, on which many locals depend.

In late 2011, the four Mekong River nations—Laos, Thailand, Vietnam, and Cambodia—announced that the dam would not go ahead until more research was conducted to allay concerns. Friction over the dam has created a rift between the Laos government and Thailand on the one side and Vietnam and Cambodia on the other, who fear the dam will hurt fish populations and river nutrients. The promised research has not come to light.

"The Xayaburi Dam is the first of a cascade of devastating mainstream dams that will severely undermine the region’s development efforts. The food security and jobs of millions of people in the region are now on the line," Ame Trandem, of International Rivers said in a press statement.

The dam will force the eviction of 2,100 local people.
A recent study in Global Environmental Change found that if the 11 currently planned hydroelectric projects are built on the Mekong River, fish populations could fall by 16 percent. According to the paper, the "results suggest that basic food security is potentially at a high risk of disruption."

But the Laos government, which hopes to see significant economic gain from the hydroelectric project, says that modifications to the dams design will allow fish and sediment to move freely through the dam.

But environmentalists also contend that the dam could result in the extinction of dozens of freshwater fish species, including the Mekong giant catfish (Pangasianodon gigas). Specimens of the Mekong giant catfish have been caught weighing up to 600 pounds (270 kilograms), but this monster fish has been overfished to the point of being listed as Critically Endangered by the IUCN Red List. Modifications to the dam may not large enough to benefit the Mekong giant catfish.