BANGKOK — Thailand is facing a deepening environmental crisis after reports of arsenic contamination in the Kok River surfaced in March following complaints from local communities in Chiang Rai and Chiang Mai provinces.
In early April, the Department of Natural Resources and Environmental Policy and Planning confirmed elevated levels of arsenic in the water. Since then, government agencies, including the Ministry of Public Health, have issued warnings advising residents not to temporarily use the river water for any purpose, including consumption or direct contact.
The Thai government has now proposed two main solutions: domestic remedies through the construction of sediment traps to reduce arsenic concentrations and the more complex route, diplomatic negotiations with Myanmar and China.
The challenge is that the source of the pollution is outside Thailand’s jurisdiction. The contaminated area is in Myanmar, where government authority is fragmented and Chinese private companies operate mining facilities.
Diplomatic Efforts Needed
Former Prime Minister Thaksin Shinawatra recently said he would use his personal connections to help resolve the issue after Foreign Minister Maris Sangiampongsa and the Chief of Defence Force made diplomatic efforts and started talks with Myanmar and Chinese authorities to resolve the situation.
Meanwhile, Senator Chiwapap Chiwatham, chairman of the Senate Committee on Natural Resources and Environment, warned that if diplomacy fails, Thailand may have to take legal action under international law.
Civic networks are planning a rally on World Environment Day, June 5, starting at the Territorial Defence Student Training Unit in Chiang Rai and marching to the Kok River Bridge. They will present a petition to the governor of Chiang Rai calling on the Thai government to work with Myanmar, China and the United Wa State Army (UWSA) to close the mines responsible for this environmental disaster.
Chinese-Backed and Illegal Mines Flourish
The Shan Human Rights Foundation reported that the suspected gold mines polluting the Kok and Sai rivers are mainly located south of Mong Hsat in Myanmar’s Shan State, about 30 kilometres from Thailand’s Mae Sai district. Since 2023, seven Chinese companies have been operating gold mines near the Kok River, discharging toxic chemicals directly into the water.
These are medium-sized mines (less than 50 rai or ~8 hectares), which also include manganese and coal operations. Thai companies were previously involved as contractors. The mining areas are under the control of the United Wa State Army (UWSA). Pollution is not limited to the Kok River, but also extends to the Sai River.
In addition, the Myanmar government has granted mining licences in Mong La, Tachileik District, indicating an expansion of gold mining due to rising global gold prices. This includes both legal and illegal mining.
According to the Singapore Bullion Market Association (SBMA), Myanmar encourages domestic and foreign investment in the mining sector. Investors must pay a licence fee of 5% in advance and receive a share of around 30% of net production. Entry into the sector is possible via foreign direct investment or joint ventures with local companies. The government is also promoting the establishment of refineries that utilise modern technologies.
There are currently 5–6 large gold mines in Myanmar, particularly in the Mandalay area, which produce 5–10 tonnes of gold annually. However, there are over 472 small-scale gold mines scattered across the country, including in Shan State.
Gold Skips Thailand, But Not Arsenic
A local source in Chiang Rai said that customs checks in Mae Sai found no gold imports from Myanmar, only manganese and lead ores. The gold mined in Shan State is probably transported via alternative routes. An important logistical route leads from Tachileik to Mong Pyak, Kengtung and then to Mong La. The route is only 244 kilometres long and takes around 5–6 hours. From there, the gold travels via Xishuangbanna to Kunming in Yunnan Province in the south of China, bypassing Thailand completely.
To extract pure gold, the ore is crushed, burnt, leached with acid and chemically separated, producing highly toxic by—products – in particular arsenic and lead. These are discharged untreated into the river systems and flow downstream across the borders into Thailand.
“A single kilogram of refined gold can be worth millions of baht. After extraction, it is shipped directly to China, where demand is high, so the logistics costs are worth it.
Meanwhile, the chemicals used in the extraction process are dumped directly into the Kok River and other waterways without treatment, so they eventually end up in Thai territory,” the source said.
This is in line with the latest findings of the Pollution Control Department. In the past two months, arsenic levels in the Kok River have exceeded safety standards.
On 27 May, Deputy Prime Minister Prasert Jantararuangtong and Deputy Interior Minister Thirarat Samretwanit, who were assigned by the prime minister to monitor the situation, visited the area. They urged the public to avoid direct contact with the river and only use treated tap water, which is still safe and meets quality standards.
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