Current water levels of the mainstream Mekong River are said to be "significantly below average" in Northern Lao PDR and Thailand.
Levels at mainstream measuring stations at Chiang Saen, Chiang Khan, Luang Prabang, Vientiane and Nong Khai are below those that occurred in the low flow season of 1993, which followed the most extreme regional drought on record in 1992.
According to the Mekong River Commission (MRC), river flows are also at their lowest levels in 50 years in southwestern China, with water flowing at only half the level that would be considered normal for this time of year.
MRC said the very low water levels recorded at monitoring stations in the mainstream between Chiang Saen and Nong Khai show that tributaries in Laos and Thailand are not feeding as much water into the mainstream as would be expected.
The severe drought will impact on agriculture, food security, access to clean water and river transport and will affect the economic development of people already facing serious poverty, the commission said.
The National Centre for Environmental Health and Water Supply in Lao PDR has started advising people to counter the effects of drought by reducing water consumption.
Following the results, the MRC will be undertaking more detailed assessments of the low flow conditions and is working with its Member Countries to closely monitor the drought situation.