BANGKOK — The Mekong River runs more than 4,000 kilometers, from China into Myanmar and then through Laos, Thailand, Cambodia and Vietnam, where it empties into the sea. Traditionally a major transport route and food source, it is also increasingly becoming a supply of energy — at its own peril and at the cost of instability among states in the region.

Several large dams already straddle the Mekong in China, and construction on more dams downstream is underway. Hydropower is a well-established source of renewable energy, and the countries of the lower Mekong see it as an attractive way to help meet their exploding energy demand while diversifying their energy portfolio. Over 80 percent of Thailand’s total energy consumption, for example, is satisfied with fossil fuels.

And so Thai, Malaysian, Chinese and Vietnamese developers and investors in the private sector have set out to build 11 dams on the Mekong’s main stem in Laos and Cambodia. Only about one-tenth of the power to be produced will go to the two host countries; the bulk will serve energy-hungry Thailand and Vietnam. Laos, the location of nine of these dams, is tapping the river, one of its few natural resources, to generate needed export revenues.

Energy security and economic development are legitimate goals, of course, but these main-stem dams were conceived with little regard for their environmental consequences and socioeconomic repercussions. The proposed dams will prevent sediment from the upper stretches of the Mekong River from reaching its delta, depriving rice fields in lower Vietnam of essential nutrients. They will also disrupt the migratory patterns of fish, which will endanger the stocks on which Cambodians, especially, rely for much of their protein intake.