This image shows a section of the Mekong mainstream with Thailand’s Loei province on the south, Laos’s Vientiane province on the north, and Laos’s Xayabouri province to the east. Note how the 2019 river color is much bluer or cleaner than the normal year of 2017. The 2019 severe drought has brought less sediment runoff into the river system this year, and the Xayaburi dam upstream holds back sediment. In turn, the muddy Mekong is turning from its normal brown to blue. This is not good – sediment is the critical building block of downstream agricultural productivity in Laos, Cambodia, and Vietnam and is necessary to produce the Mekong’s annual 2.6 million ton fish catch, the largest in the world for a single river. The low river levels are caused by an extended drought which basically supplanted this year’s monsoon season. More than fifty dams upstream in Laos and China also contribute to low levels and the incremental effect of the recently opened Xayaburi Dam, a few hundred kilometers upstream, is certain but unknown.
