Vientiane, Lao PDR, 3 July 2026 – The Mekong River Commission (MRC) Secretariat reported that recent arsenic testing from four monitoring rounds in Luang Prabang and Bokeo Province, Lao PDR, found concentrations at all monitored sites to be within the standard limit of 0.01 mg/L.

The analysis covered samples collected on 10 May, 22 May, 5 June, and 24 June 2026 at three sites: Luang Prabang; Bokeo C2, located upstream of the confluence of the Ruak River with the Mekong River by about 10 kilometres; and Houay Xay C5, located downstream of the confluence of the Kok River with the Mekong River by about 32 kilometres.

For the three latest sampling rounds on 10 May, 22 May, 5 June 2026, and 24 June remained below the 0.01 mg/L standard limit.

Note: The standard limit of arsenic concentration is 0.01 mg/L, in accordance with the Technical Guidelines on the Implementation of Procedures for Water Quality (TGWQ).

The samples were analysed by the Biotechnology and Ecology Institute (BEI) of the Environmental Quality Analysis Centre in Lao PDR, using standard methods under its ISO/IEC 17025:2017-accredited quality management system. The results provide an updated technical snapshot of arsenic levels at the monitored locations during the sampling period and will contribute to continuing evidence-based assessment of Mekong water quality conditions. The latest sampling results will be regularly updated.

“The latest findings are reassuring, but they should also remind us why regular monitoring is essential,” said Ms Busadee Santipitaks, Chief Executive Officer of the MRC Secretariat. “Conditions in a large river system can change over time, and continued testing allows countries to detect trends early and respond timely with confidence.”

The MRC Secretariat has emphasised consistently that water quality monitoring is an important part of its broader technical work to support Member Countries in understanding changes in the Mekong River system. The Secretariat will continue working with national agencies and partners to strengthen monitoring, improve access to reliable data, and support coordinated responses where needed.

The results also underscore the role of routine, site-based scientific assessment in informing communities, decision-makers, and stakeholders. Continued cooperation among Member Countries remains central to protecting the Mekong River and supporting shared, sustainable benefits across the basin.

About the Mekong River Commission

The MRC is an intergovernmental organisation established in 1995 to boost regional dialogue and cooperation in the Lower Mekong River Basin. Based on the Mekong Agreement among Cambodia, Lao PDR, Thailand, and Viet Nam, the MRC serves as both a regional platform for water diplomacy and a knowledge hub – to manage water resources and support sustainable development of the region.

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 For more information, please contact:

Chandaly Mao (Ms.)

Communications Officer for Press

Mekong River Commission Secretariat

Email: chandaly@mrcmekong.org