Low Mekong Levels Raise Toxic Algae Risk

11 Dec 2019 by Staff - Water Diplomat

The Mekong River Commission (MRC) has suggested that receent change in colour of the Mekong River in Thailand and Laos with serious consequences, and called for more data sharing with the China-backed Lancang-Mekong Cooperation Mechanism.

The MRC attributed 9 December the vibrant blue-green color observed in Nakhon Phanom province to low river flow and a drop in river sediments in addition to the presence of algae both on sand and the river bottom.

Low flows are attributed to a record drought, exacerbated by upstream hydropower dams in China and Laos. There is also concern that fertilizers used in agriculture could leach into the river, feeding algae. The possibility of toxic algae bloom arising from rotting algae has not been excluded, and possible that similar color changes could occur elsewhere along the river.

The region is biologically diverse and millions of farmers and fishermen are dependent on the Mekong River. Current river levels will reduce the food available for insects and small fish and will reduce the size of fish catches, with a direct negative impact on local communities.

It is possible that the current conditions could prevail until such time as the river flow increases but the next flood season is not expected until May. Alternatively, flow would increase if water is released from upstream storage reservoirs.