High levels of arsenic found in the Kok and Sai rivers — contamination exceeds safety standards by several times.The source is believed to be a mining operation across the border in Myanmar.

Arsenic Contamination in Kok and Sai Rivers Traced to Mining Operations in Myanmar

The arsenic contamination exceeding safety standards in the Kok and Sai Rivers has been linked to mining activities upstream, where mining is being carried out differently at each site. These operations, backed by Chinese investors, reportedly lack proper wastewater treatment systems. As a result, toxic substances from mineral extraction processes have been discharged directly into the rivers. The headwaters of both rivers are sites of gold and rare earth mineral mining.

In the case of the Kok River, contamination has been present since 2024, when land-clearing for mining began in the upstream area. However, no tests for heavy metal contamination in the river were conducted last year.

As for the Sai River, flooding occurred last year, and the Provincial Waterworks Authority detected heavy metal contamination in water samples. However, the issue received little public attention at the time.

Recent sediment testing in both rivers has revealed arsenic contamination, indicating that arsenic is present not only in the water but also in the riverbed sediment. Small aquatic animals that feed along the sediment are absorbing the toxin, potentially impacting people who consume these animals.

The impact of arsenic contamination in the Kok and Sai Rivers—now well above safety thresholds—has caused riverside restaurants in Mae Ai District and Mueang Chiang Rai District to shut down in large numbers.

Proposed solutions include:

1. A complete halt to mining operations in neighboring countries.
2. Government negotiations with neighboring authorities to introduce and enforce environmentally friendly mining practices.

If the Thai government fails to resolve the arsenic contamination in the Kok and Sai Rivers, the ongoing crisis will continue to harm local communities—economically, environmentally, and in terms of public health. The long-term outcome may include a rise in toxin-related illnesses among affected populations.

Source: https://www.thairath.co.th/scoop/theissue/2856171?gallery_id=4

Photo by : Office of Environmental and Pollution Control Region 1, Chiang Mai