As Thailand’s Salween River joins a growing list of contaminated waterways in the country, a new investigation asks why the state keeps managing damage, while refusing to confront its source
The Salween River is one of Southeast Asia’s great transboundary rivers. In this piece in The Momentum, Phiphatphong Sriwichai looks at how it has become Thailand’s fifth “forbidden” river, unusable for drinking, farming, fishing, or daily life.
The story begins with a grim sense of déjà vu. In late 2024, residents along the Kok River noticed an unusual cloudiness in the water. Tests later revealed suspected contamination from heavy metals such as mercury, lead, and arsenic, believed to originate from gold and rare-earth mining operations in Myanmar’s Shan State. A year later, rather than resolution, the crisis has multiplied. The Kok remains off-limits, and three more rivers, the Ruak, Sai, and Mekong, have been added to the list. Now, the Salween has joined them.
In September 2025, researchers from Chiang Mai University’s Environmental Science Center detected arsenic levels in the Salween River at four to five times above acceptable standards. For communities in Mae Hong Son Province who rely on the river for food, transport, and income, this discovery confirmed what they had already sensed through sight and taste. Yet, as Sriwichai documents, official action once again lagged behind local alarm.
Environmental advocates such as Pianporn Deetes of Rivers and Rights argue that the source of contamination is not mysterious. Mapping by the Stimson Center shows more than 126 gold and rare-earth mines clustered near tributaries feeding the Salween. Despite this, the Thai government has avoided formally attributing blame to upstream mining in Myanmar. Conflicting statements from senior officials, some acknowledging mining as the cause, others denying sufficient proof, have further muddied the waters.
As a result, state intervention has focused on monitoring and risk reduction rather than prevention. Letters requesting cooperation from Myanmar have gone unanswered for over a year. Without confirmation of the pollution’s origin, authorities claim they cannot halt the flow of toxins.
One of the report’s most damning findings is that civil society, not the state, has driven nearly every meaningful response. Villagers were the first to collect water samples. University researchers conducted repeated tests. Only then did agencies such as the Pollution Control Department step in, conducting fewer inspections despite having far greater resources. Even health testing has been limited, with only a handful of villagers screened once, and no follow-up.
As Sriwichai makes clear, the Salween crisis exposes a deeper failure. Treating contamination as a series of isolated incidents rather than a systemic, cross-border problem allows the state to manage symptoms while avoiding responsibility.
This original source article หรือต้องปนเปื้อนทั้งประเทศ รัฐจึงจะแก้ไขปัญหาที่ ‘ต้นตอ’ เมื่อสาละวินเป็นแม่น้ำปนเปื้อนอีกแห่ง by Phiphatphong Sriwichai was published in Thai in The Momentum on January 7, 2026.
It is available here.
The Momentum is an independent Thai news and analysis platform covering politics, society, environment, and culture across Thailand and Southeast Asia.
Summary ZN
