CHIANG RAI – Officials have stepped up testing for contamination in local rivers, with urgent action now underway by several agencies. At the mouths of the Kok and Khum rivers, infected giant catfish have been found. Fishermen who caught them released them back into the water.
On 1 May 2025, after earlier arsenic tests in the Sai, Ruak and Mekong rivers at nine locations on 30 April, initial test kits found arsenic levels in some spots up to 19 times above the standard.
Dr Suebskul Kitchanukorn from the Social Innovation Office at Mae Fah Luang University led a team of scientists to collect more samples. These will be analysed in the lab for heavy metal contamination, which could impact the health of people living along the Sai River.
Dr Suebskul explained that the new samples will go through scientific testing in the lab to find out the exact levels of harmful metals. Results should be ready in three to four days. Once confirmed, the findings will be passed to the relevant authorities for proper follow-up.
Somkiat Khueanchiangsa, President of the River for Life Association, visited the Kok River after reports of fish infections, likely caused by mining pollution upstream.
Today, only a few fishermen were out, mostly catching yellow catfish, which showed no signs of illness or unusual changes. He spoke with locals to keep track of what’s happening with the fish and other river life.
“This visit is part of our ongoing checks on chemical pollution in the Kok River. At the mouths of both the Kok and Khum rivers, we’ve found infected giant catfish. Fishermen who caught these fish released them back into the river.
We’ll collect more fish samples for lab analysis to check for contaminants. The River for Life Association is now working with local universities and the Chiang Rai fisheries office to monitor fish and aquatic life in the Kok and Khum rivers, both Mekong tributaries.
We’ll keep a close eye on any impacts as the situation develops,” Somkiat said.
Meanwhile, long-tail boats used for transport and tourism at the CR Pier in Chiang Rai remain idle along the riverbank. These boats, usually busy with passengers, have barely moved in recent days.
This follows a recent report from the Office of Environment and Pollution Control Region 1 (Chiang Mai), revealing high arsenic levels in the Kok River.
Mr. Thawat, 56, who operates a long-tail boat on the Kok River, shared that over 30 boats work this stretch of the Kok River, with about 10 moored at the CR Pier in Chiang Rai. Normally, the rainy season means fewer customers, but most boat operators could still expect one or two trips each day.
However, since the arsenic discovery of Arsenic in the Kok River, his business has dropped off completely. Over the last four or five days, not a single customer has hired a boat. Fear of arsenic seems to be keeping people away.
Boat operators also worry about their safety. If they must come into contact with the river, they wash with clean water right after to reduce health risks. Prolonged arsenic contamination would hurt local boat businesses and disrupt the lives of riverside communities.
Residents can’t catch crabs or fish as before, and can’t use the river water for other needs. Some may have to consider new jobs, but many have been boat operators all their lives and don’t know what else they could do. Mr. Thawat hopes that the government and related agencies will address this problem quickly.
