Mekong river near Chiang Khan

The Mekong often suffer under the low water level. Boats sometime only can go up and down the river if China opens their water gates at their dams.
A number of dams have already been built on the river's tributaries. This has been criticized on grounds of cost as well as damage to the environment and to the livelihoods of affected villagers, though none have been built on the main part itself.
China is engaged in an extensive program of dam-building on the river itself: it has already completed one at Manwan, a second is under construction at Dachaoshan, and another twelve are under consideration.