Authorities in Chiang Rai, Thailand are investigating dangerously high arsenic levels found in local rivers while also monitoring reports of infected fish potentially linked to upstream mining contamination.

CHIANGRAI, 2 May 2025  – Authorities in Chiang Rai province, northern Thailand, are urgently investigating elevated levels of arsenic detected in the Sai, Ruak, and Mekong rivers.

Preliminary tests conducted at nine locations last month revealed arsenic concentrations exceeding safety standards by up to 19 times in some samples. Further testing is being carried out in a laboratory to confirm these initial findings.

A team of scientists from Mae Fah Luang University, led by Dr. Suebsakun Kidnukorn, collected additional water samples for comprehensive heavy metal analysis, with results expected within three to four days. These findings will be shared with relevant agencies to implement appropriate corrective measures.

Separately, concerns have been raised about potential water contamination from upstream mining activities affecting the Kok River.

Somkiat Khuanchiangsa, president of the Living River Siam Association, is monitoring the situation after reports of infected fish.

While initial observations found mostly healthy green catfish, some infected Asian redtail catfish were discovered near the estuaries of the Kok and Kham rivers, tributaries of the Mekong. Samples of these fish will also undergo laboratory testing for contaminants.

The Living River Association is collaborating with academic institutions and the Chiang Rai Fisheries Department to monitor the health of aquatic life in the affected rivers. 

Source: TNA