According to NPR, Laos is building several dams on the Mekong and there’s an argument about whether the fish passage systems that have been designed will be effective:

“I’m confident that the mitigation measures we can employ here will allow fish to pass the barrier we’re going to create. From studies we’ve done, the impacts people are saying the project will cause, change in flow, quality, sediment distribution, fish food, none of those things are going to arise from this project.”

The risks the dolphins downstream face are real, Hawkins says, but he says that’s because of bad fishing practices, tourism and poor management. As for migratory fish that use the Hou Salong channel, Hawkins says, the fish passageways his company, Megafirst, are building around the site should take care of the problem…

“The effectiveness of such fish passage mechansims is quite OK, let’s say, quite well proven for European or North American rivers, where we have small number of species that are well known,” Meng says. “But in the Mekong, we don’t have five fish species which we have to take care of, we have 70, maybe even more, and we have no clue about them. So building something for them to migrate up and down with, that’s just guessing at the moment.”

Trandem of International River says fisheries experts estimate that at least 43 species of fish are likely to go extinct because of the impact of the dam, including the Mekong giant catfish, the world’s largest. Sedimentation — the silt the river carries downstream to Cambodia and Vietnam — is another problem. The Xayaburi will have major food security implications as well, Trandem says.

“By blocking sediment, we know that where there’s a lot of agricultural productivity and rice growing, these areas are going to suffer a lot because they’re no longer getting the same nutrients,” she says. “And so this will have a significant impact, especially in the Cambodian flood plains but also in Vietnam’s ‘rice bowl,’ which is really the center of rice production for region.”

This is all interesting to me because of the question of whether technology like fish ladders can mitigate our environmental impacts. Even if it can, I don’t doubt for a second that there is a lot of bad development going on that will impact the ecosystem regardless of what is done with fish passage.