Chiang Rai – The Office of Natural Resources has reported that fish and other aquatic life in the Mae Kok River are dying from an unknown cause following the discovery of arsenic levels exceeding safety standards in Chiang Rai province.
On 7 April 2025, The Office of Natural Resources and Environmental Policy and Planning, tested water and sediment samples and found arsenic contamination at three separate sites.
Local residents noticed the water had an unusual murky appearance, and dead fish and aquatic animals, including freshwater turtle hatchlings, were found dead along the riverbanks.
Tests conducted by The Office of Natural Resources in Mae Ai District, Chiang Mai, and Mueang Chiang Rai District revealed arsenic levels in the water at 0.012 milligrams per liter, surpassing the standard limit of 0.01 milligrams per liter.
The Mae Kok River water had a distinct grayish hue, leading locals to avoid using it. Fishing, consumption, and other activities involving water from the Kok River have been halted out of concern for safety.
Mr. Apichit Panwichai, a resident in the area, shared that the river was once a vital resource for fishing and daily use. However, the arsenic contamination has caused widespread concern.
Many now avoid contact with the water, including tap water sourced from the river, fearing health risks. Residents are urging authorities to collaborate with neighbouring countries to address the root cause, particularly mining activities suspected of releasing contaminants into the river.
Chiang Rai Governor Charin Thongsuk has ordered thorough water quality checks, collecting samples from the river’s source to its confluence with the Mekong River in Chiang Saen District.
Relevant agencies, including public health, water supply authorities, and local governments, have been called upon to assess water usage for activities like agriculture, industry, and tourism. Findings are expected by 9 April 2025, which will guide plans for tackling the issue comprehensively.
The Office of Natural Resources has ordered water quality checks 1-2 times per month and warns residents not to drink or use water from the Mae Kok River directly. Anyone experiencing symptoms like skin irritation or vomiting should seek medical attention immediately.
Authorities assure the public that tap water remains safe and meets quality standards.
