CHIANG RAI: Each day, Siam Kaewdam casts his fishing nets into the Kok River, letting them drift downstream before paddling out later in his wooden boat to haul in his catch.
The 49-year-old fisherman has found slim pickings of late. His haul of mostly perch and a local catfish variety prized for its tasty pairing with tom yam broth currently fetches barely a third of its regular market price.
Farther upstream, about an hour by boat from the northern Thai city of Chiang Rai, the Ruammit Elephant Village, once a drawcard for tourists eager to bathe and play with elephants, has sat eerily quiet and desolate for most of the past year.
Boats that once ferried visitors along the Kok River to the elephant camp, nearby hot springs and other riverside tourist spots, also lie disused.
“Normally when you come here in March or April, this area is absolutely packed with tourists,” said elephant caretaker Phichet Thuraworn.
Now, said the 36-year-old, the camp often closes early by mid-afternoon without seeing a single visitor. “We have no sign of when things might recover.”
The silence along the Kok River is the fallout from a toxic surge upstream. While the river should run clear, it is now thick and cloudy with sediment, industrial run-off and heavy metals amid a boom in unregulated, China-backed rare earth mining in post-coup Myanmar.
Driven by the global race for the highly strategic minerals, this cross-border contamination is poisoning Thailand’s waterways, crippling its tourism and leaving downstream communities to pay the price for a high-stakes geopolitical rivalry.
Flowing from Myanmar’s mountainous Shan State into northern Thailand, the Kok River has long been the lifeblood of fishing, farming and tourism-dependent communities.
But over the past year, researchers and policy analysts have pointed to mounting evidence of a surge in unregulated rare earth and gold mining across the border in Myanmar as a major source of contamination, releasing heavy metals and toxic run-off into the Kok River, a significant tributary of the Mekong.
The river, which typically runs clear during the dry season in the first half of the year, is now thick and turbid.
Analysis by US think-tank the Stimson Centre, using high-resolution satellite imagery and field data, has identified dozens of new mining sites in Myanmar’s Shan State.
The surge in mining has been fuelled in part by the instability following Myanmar’s 2021 military coup, which has weakened oversight in border regions and allowed illicit operations to proliferate.
At the same time, China’s voracious appetite to extend its global supply chain dominance in rare earths – the strategic minerals used in everything from electric vehicles to defence technology – has incentivised rapid extraction.
The mining process for rare earths is notoriously toxic, particularly if appropriate precautions and site remediation are not adequately taken.
Injecting water mixed with fertiliser or acid into deforested hillsides creates a liquid slurry that collects in downhill pools to separate the rare earth raw materials.
Siphoned river water is then returned to local rivers, poisoning water supplies.
On the ground, Thai university researchers have detected heavy metal contamination exceeding safety standards across the Kok River basin, with arsenic readings more than double Thailand’s national standard of 0.01mg per litre.
And in February, researchers from Chiang Rai’s Mae Fah Luang University released a paper reporting arsenic accumulation in people living along the river, including several test participants exhibiting neural and musculoskeletal symptoms consistent with heavy metal poisoning, sparking heightened concern among local communities.
Thai authorities have sought to calm public anxiety. The Ministry of Public Health has carried out its own testing of residents, showing arsenic levels within accepted limits and stressing that there is no immediate health risk based on current exposure.
The provincial authorities have increased water quality monitoring and urged residents to rely on treated tap water rather than direct river use, while acknowledging the need for continued surveillance of cross-border pollution upstream.
The Ministry of Environment’s Pollution Control Department said in March that continuous monitoring has shown that while most heavy metals remain within acceptable limits, arsenic levels continue to exceed standards in parts of the Kok, Sai and Mekong rivers.
But researchers say Thailand lacks clear benchmarks for what constitutes dangerous levels of arsenic over long periods of exposure, given its propensity to accumulate in the human body over time.
“We face the accumulation of heavy metals: In the environment, in the food chain, in the human body – it slowly accumulates,” Dr Suebsakun Kidnukorn from Mae Fah Luang University in northern Thailand told The Straits Times.
“We don’t know when we will have some risk, or physical change, or even cancer. This is what concerns us most.”
Much of Myanmar’s rare earth mining activity is concentrated in resistance-held territories out of reach of the ruling junta’s military government.
While formal ownership is opaque, researchers have identified mining sites consistent with Chinese extraction methods, while field reporting has documented Chinese-speaking managers and workers at some operations.
Myanmar’s exports of rare earths also flow almost exclusively to China, which dominates global processing of the materials.
China relies heavily on Myanmar’s rich deposits of heavy rare earths to complement its own supply to meet global industrial demand, especially as Beijing tightens environmental restrictions on mining within its own borders.
While acknowledging the difficulty of engaging war-torn Myanmar or its larger trading partner, China – which has displayed no political motivation to intervene – Dr Suebsakun said Thailand could leverage its role as a transit hub between Myanmar and China for critical minerals such as antimony, manganese and tungsten to bring both parties to the table.
“We need political will from the (Thai) government to take this issue seriously,” he added.
The wave of alarming headlines has ignited concerns over food and water safety and long-term health consequences, while are already having a devastating effect on local livelihoods.
The resulting dilemma has left local communities torn between advocating for stronger action and greater clarity from the authorities and wanting to downplay the reputational damage that has been disastrous for tourism and the sale of agricultural produce – from fish and vegetables to the region’s high-quality glutinous rice, used in mango sticky rice.
In addition, the fuel crisis and hit to tourism due to the ongoing Middle East crisis have only exacerbated existing financial pressures.
“We want clarity on how much of the fish and water is safe to consume, and how long we can stay in this situation,” said Chayakorn Namphaphiwat, the head of Farm Samphankit village near Chiang Rai.
“But there has been a lack of a clear response from the government.”
Siam, the fisherman, is one of the test subjects whose fingernail and urine samples returned a higher than normal reading of arsenic in the Mae Fah Luang study.
While initially alarmed upon hearing the news, he said he has felt no abnormal physical symptoms.
In any event, he added, the public reaction to the news of the river pollution was having a much more pressing impact on his immediate livelihood.
This is not the first time his village in Sob Kok, at the confluence of the Kok and Mekong rivers, has suffered ecological disruption due to the whims of economic development upstream.
Siam said the upstream Chinese construction of giant hydropower dams along the upper Mekong, or Lancang River, has led to fluctuating water levels and a 70 per cent fall in the fish population in his area.
As well as the turbid water quality, the higher river bed from silt and sediment, likely from mining run-off, has led to a reduction in fish swimming upstream to lay eggs, he added.
“Our village has suffered from twin disasters,” Siam said.
The usually lucrative Songkran season is unlikely to offer much relief. The Thai New Year festival starting on April 13 typically draws crowds of locals and tourists to the riverbanks of Chiang Rai, where they gather to splash water, escape the searing summer heat and take part in symbolic cleansing rituals.
But in 2026, fears of contamination in the Kok River have severely dampened visitor interest. And if that were not enough, the global energy shock linked to the Middle East conflict has further eroded travel appetite, delivering yet another blow to an industry already on its knees.
So central is the Kok River to daily life that its troubles reach far beyond economic livelihoods, affecting almost every aspect of how communities live – from fears about the safety of the water supply to that of the produce grown for personal consumption in the various vegetable plots along the riverbanks.
Phichet, the elephant caretaker, said he has lost one of his favourite hobbies: winding down after work by going fishing with his friends.
And instead of preparing for a bumper tourist season, Phichet said the company he works for has sold more than half of its elephants to camps in other parts of Thailand in order to cover wages and other expenses.
Boat hire operator Srithon Kamsaen, 66, said that many local business owners are reaching breaking point. “In the long run, I don’t know how we can remain open.” - The Straits Times/ANN
