For nearly six decades, Thai farmer Tip Kamlue relied on the Kok River to irrigate her fields in northern Thailand. But since April, she has been forced to abandon the river and switch to groundwater after authorities issued contamination warnings.
“It’s like half of me has died,” said the 59-year-old, standing beside her crops in Tha Ton and staring at the river she once depended on to grow pumpkins, garlic, sweet corn and okra.
Her situation reflects a growing environmental crisis across mainland Southeast Asia. A new study by the U.S.-based Stimson Center has identified more than 2,400 mines — many unregulated or illegal — that may be leaching toxic chemicals such as mercury and cyanide into major river systems, including the Mekong, Salween and Irrawaddy.
“The scale is something that’s striking,” said Brian Eyler, senior fellow at Stimson. Researchers used satellite imagery to map out mining activity, identifying 366 alluvial sites, 359 heap leach locations and 77 rare earth mines draining into the Mekong basin.
Most of these sites are believed to extract gold — often with mercury and sodium cyanide — while rare earth mines use other hazardous chemicals such as ammonium sulphate. Rare earth mining has rapidly expanded in Myanmar since 2021, with operations often backed by Chinese interests.
Tanapon Phenrat of Thailand Science Research and Innovation, who analysed Kok River samples earlier this year, confirmed traces of arsenic and heavy rare earths such as dysprosium and terbium. He warned that contamination levels could escalate dramatically unless mining is halted.
Millions risk exposure to contaminated water. The Mekong alone supports more than 70 million livelihoods, and Eyler cautioned that the health risk extends beyond Asia. “There is not a major supermarket in the U.S. that doesn’t carry products from the Mekong Basin, including shrimp, rice and fish,” he said.
In response, the Thai government has established three task forces to coordinate international action, monitor health impacts and seek safe water sources for river-dependent communities.
But for farmers like Tip, the damage feels deeply personal.
“I just want the Kok River to be the way it used to be — where we could eat from it, bathe in it, play in it and use it for farming,” she said.
“I hope someone will help make that happen.”
