Laos Dam Poses Environmental Dangers to Lower Mekong Basin

Plans for the newest hydropower dam on the Mekong River will need dramatically improved environmental safeguards in order to minimize damage to fish and other wildlife in the river basin, researchers say.

Ahead of a regional consultation on the project today in Vientiane, the intergovernmental Mekong River Commission released a draft report on the proposed Pak Beng dam in northern Laos, saying the amount of water that would flow through proposed fish passages are less than a tenth of recommended levels. It also issued a slew of other recommendations.

Plants line the bank of the Mekong River near the Pak Beng dam site. (International Rivers)

The passages are needed to help fish—ranging from larval drift to the Mekong giant catfish, the world’s largest freshwater fish—move between the two sides of the massive 912-megawatt dam, says the report set to be presented at the forum.

The dam, “if designed and operated as outlined in the documents submitted, will impact on fish passage, downstream sediment transport, and aquatic habitats,” says an email sent by the commission’s secretariat on Thursday.

“These may have knock on impacts on the people and economy of the Lower Mekong Basin,” the email says, adding that these would likely be felt across country borders.

While the international standard for water flow through a dam’s fish passage is 10 percent of the river flow—allowing the fish to easily swim up or downstream—the proposed rate is less than 1 percent, the report says. It also notes a need to attract fish to the passages’ entrances and to add more exits.

The dam’s developer—China Datang Overseas Investment Company—and the Laotian government failed to provide enough information about their plans during the assessment, the report adds.

“Some impacts are unavoidable,” the email from the Mekong River Commission secretariat says, adding that implementing the recommended changes was beyond the commission’s mandate and “final decision[s] rest with the proposing country.”

Two previous consultations on a dam built downstream of Pak Beng, and another under construction on the Cambodia-Laos border, had stalled, but construction moved ahead anyway.

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