Recent tests by Thai government agencies have revealed alarmingly high levels of pollutants in a number of rivers across northern regions of the country.
The toxic pollution is threatening local fishing activities, and Thai officials suspect the cause is stemming from waste discharged by upstream mining operations in neighboring Myanmar.
In early April, the Pollution Control Department under Thailand’s Ministry of Natural Resources and Environment tested water quality in the Kok River in Chiang Mai province after local residents reported unusual turbidity and skin rashes following contact with the water, The Nation newspaper reported. The Kok River originates in Myanmar’s Shan State and flows across the Thai border. Arsenic levels in samples collected from multiple sites ranged from 0.012 to 0.026 milligrams per liter (mg/l) – exceeding the national safety limit of 0.01 mg/l – while turbidity levels were nearly 10 times above normal.
In May, further tests by the Pollution Control Department in Chiang Rai – another northern province – showed more alarming results. Water samples taken from tributaries feeding the Mekong, Kok, and Sai rivers showed significant contamination. Lead and arsenic were detected at several points near the Mekong and Sai rivers, with three samples from the Sai River registering arsenic levels 44, 45, and 49 times higher than the national safety standard. The report also noted that several local fish were found with ulcers and signs of inflammation, according to the Bangkok Post newspaper.
The severity of the contamination prompted the country’s Public Health Ministry to issue a warning advising Chiang Rai residents to avoid eating freshwater fish until further notice. The report also cited Suebsakun Kidnukorn of Mae Fah Luang University, who noted that the impacts of worsening pollution were becoming evident: fishermen were losing business, and restaurants had stopped purchasing fish from the Kok River.
Similar irregularities have also been observed in fish from the Mekong River – the longest river in Southeast Asia and a vital regional waterway – heightening concerns about the possible widespread effects of pollutants.
Thailand’s Deputy Prime Minister Phumtham Wechayachai attributed the pollution to toxic waste from unregulated mining activities in Myanmar, which shares borders with both Chiang Mai and Chiang Rai. He noted that efforts to coordinate with Myanmar’s central government have failed, as the mining operations are located in territories currently controlled by rebel groups.
To alleviate the issue without Myanmar’s collaboration, Wechayachai has called for dams on the Sai and Kok rivers, with an estimated budget of THB 7 billion (USD 215 million, EUR 185 million), aimed at filtering and trapping heavy metals, The Nation reported on 21 May.
Myanmar has been locked in a nationwide civil conflict since a military coup led to a shift in power in 2021. In many regions along the Thai-Myanmar border, central authority has collapsed, allowing militias and insurgent forces to dominate territory, including in resource-rich areas increasingly exploited with little or no environmental oversight.
Chinese investors are behind the mining operations in Shan State believed to be contributing to river pollution, according to Lalita Hanwong, a Myanmar affairs expert at Thai Kasetsart University and advisor to Thailand’s House of Representatives Committee on National Security, Border Affairs, National Strategy, and National Reform.
Speaking at an informal public hearing held by two Senate committees in Chiang Rai on June 4, as reported by Thai PBS, Hanwong said the mines are located in areas controlled by the Red Wa ethnic group and the United Wa State Army (UWSA), one of Shan State’s largest armed organizations. Hanwong emphasized that addressing the crisis would require dialogue not only with Myanmar but also with China, the Red Wa, and the UWSA.
On 24 May, a number of Thai academics and civil society groups voiced similar concerns during a public event in Chiang Rai, linking the river contamination to mining activities for gold, manganese, and rare earth elements across the border in Myanmar.
International Rivers Campaign Director Pianporn Deetes presented satellite imagery from Thailand’s Geo-Informatics and Space Technology Development Agency (GISTDA), showing over 40 mining sites established within the past two years in territory controlled by the Wa group. Deetes alleged that Chinese companies had secured mining concessions in the area without consulting downstream communities, stressing that “these areas operate outside the scope of international environmental regulations and are a major source of river pollution.” The participants called on the governments of Thailand, Myanmar, and China – as well as the UWSA – to shut down the mines believed to be responsible, The Nation reported on 25 May.
