China completed its first mainstream hydropower dam on the Mekong, the Manwan dam in Yunnan province, in 1995, and has since planned and built 10 more. Eleven hydropower dams are in various stages of planning and construction in Laos and Cambodia on the mainstream of the Mekong river, along with hundreds of dams on its tributaries.
Energy demand is expected to increase by 6-7% each year in the Lower Mekong Basin through to 2025, and hydropower has proved an important alternative to fossil fuels. Between 2005 and 2015, electricity generation from Lower Mekong Basin hydropower increased from 9.3 GWh to 32.4 GWh.
Hydropower is also valuable to Lower Mekong Basin countries as a source of income and foreign investment. The Xayaburi dam in Laos, for example, is one of only two completed dams on the lower Mekong mainstream and sells more than 95% of the power it produces to neighbouring Thailand. Economic gains from hydropower development are expected to rise to as much as USD 160 billion by 2040, according to the Mekong River Commission.
In full: https://www.thethirdpole.net/en/energy/what-are-the-impacts-of-dams-on-the-mekong-river/