Southeast Asia is betting on hydropower, but there are risks of economic damage
Ladders, according to Goichot, are costly and only suited to fish with the right swimming ability. “With the Mekong’s diverse number of species, we simply don’t know if all fish will be able to pass through the ladder,” he said. “Colombia’s had the most success with fish ladders for about five species, but in the Mekong, you get more fish biomass in one hour than the entire year in Colombia.”
In the United States, the Mississippi River Delta is sinking due to insufficient sediment supply and officials have taken to reconstructing natural sediment flows — a highly expensive feat that isn’t feasible for developing Southeast Asian nations.
Also complicating the process is the fact that review processes for tributary dams isn’t covered under the mandate of the Mekong River Commission. Instead, “they come together under often murky, non-transparent circumstances and often have zero mitigation measures for key environmental flows,” said Brian Eyler, director of the Southeast Asia program at Washington-based policy research organization the Stimson Center.
None of the seven Chinese-built dams on the Nam Ou cascade in northern Laos, for example, have fish ladders or sediment flushing gates, he added.
Vietnam, for one, has already urged Laos to rethink its plans for more dams.
“Vietnam wants all upstream Mekong River nations to adopt proper policies in exploiting the river, especially in hydropower dam construction, in order to ensure rights for downstream nations, like Vietnam,” Vietnamese Minister of Natural Resources and Environment Tran Hong Ha said at a 2017 conference.