Arsenic Pollution in Thailand’s Rivers: A Growing Threat from Myanmar Mining Operations

Last month, officials were seen collecting water samples from one of northern Thailand’s rivers, casting a concerned eye over a grave environmental issue looming over the region. The Pollution Control Department (PCD) has raised the alarm after confirming perilous levels of arsenic and other heavy metals polluting the Kok, Sai, and Mekong rivers. Tracing the sinister trail of contamination, they pointed fingers at upstream mining operations across the border in Myanmar’s Shan State.

The PCD has brought to light the findings from their three rigorous rounds of water and sediment sampling conducted between March 19 and May 16. As they reveal the unsettling tale, the extent of pollution sweeping through these northern waterways becomes starkly apparent.

Of all the contaminated waters, the Kok River stands out with the highest levels of toxins, especially between Tha Ton in Chiang Mai’s Mae Ai district and Chalerm Phrakiat Bridge in Muang district of Chiang Rai. Tales of woe spill over as arsenic concentrations at some spots soar to an eye-watering 0.44 milligrams per liter (mg/l) — a shocking 40 times above the safe level of 0.01 mg/l. Lead, a fellow dangerous guest, peeks over safety thresholds, reaching 0.076 mg/l near the Thai–Myanmar border in Chiang Rai. While other metals like cadmium, mercury, and manganese play nice within safe ranges, they do little to quell the rising waves of concern as arsenic persists like an uninvited specter.

A representative from the PCD lamented, “Water quality along the Myanmar border is marred by elevated turbidity and arsenic, clear indicators of mining’s destructive shadow.” Previously peaceful waters, monitored from 2014 to 2015, showed no such contamination — indicating a recent surge in what is now a troubling trend.

When the sediment was thoroughly investigated in March and April, alarm bells rang louder as levels of arsenic, lead, and other heavy metals leaped above safe thresholds for benthic creatures clinging to the river floor. Locations like Tha Ton, Ban Mae Salak, Ban Ja Der, and Chalerm Phrakiat Bridge 1 emerged as high-risk areas. Health experts are waving cautionary flags, warning that feasting on local fish could introduce long-term health risks that hang like Damocles’ sword over unsuspecting residents.

The PCD’s grave concern revolves around the silent threat of chronic exposure to these metals, especially arsenic, which could lead to serious health effects even if symptoms do not immediately come forth to greet the unsuspecting populace.

Further downstream, past the Yonok Nakorn Bridge and Ban Saeo in Chiang Saen district of Chiang Rai, arsenic levels shyly dip within acceptable bounds, credited to the calming influence of sedimentation at Chiang Rai weir. Here the ballet of water slows, coaxing contaminated particles to gently settle, much like a snowfall.

Yet, over in the Sai River, intertwining with the Mekong in Chiang Rai, arsenic still insists on outpacing safety standards at every sampling site. Concentrations linger between 0.044 to 0.049 mg/l, audaciously surging higher than those spied in the Kok River. Initially sulking over safety standards, lead found its manners, finally returning to proper conduct in the third round of testing.

While the Mekong River mostly keeps its elemental temper in check, arsenic whispers of its ongoing concerns. In Chiang Saen district, readings hit a peak of 0.036 mg/l before gently slipping to 0.025–0.026 mg/l in the latest wave of samplings.

The tributaries too play their part in this alarming drama. Rivers like the Fang, Korn, Lao, and Suai show erratic bursts of nickel, arsenic, and chromium, with Korn River leading the high-score charts for contaminants. The PCD postulates that arsenic snakes into the Mekong, tagging along the inflows from the Sai and Ruak rivers, tracing back to their Myanmar origins.

Natural Resources and Environment Minister Chalermchai Sri-on confronted the country’s limited powers over pollution flowing in from foreign lands. Mining operations in Shan State, under the United Wa State Army, are blamed as the primary villains in this ecological saga.

“Resolving this will not be as swift as a blink,” Minister Chalermchai sombrely noted. “As the roots stretch into foreign territory, we must tread a cautious path using diplomatic channels, one tentative step at a time.”

For a short-term reprieve, the ministry has drawn up plans for check dams, hoping to snare contaminated sediment before it can proceed downstream. The Department of Water Resources is edging towards designing this framework, which could tally over a staggering 7 billion baht, as highlighted by the minister.

Sitang Pilailar, an expert in water resources from Kasetsart University, emphasized that these proposed check dams must be masterminded to manage fine sediment without crumbling under high pressure.

“If such a dam were to fail, the situation could spiral into something worse,” she cautioned. “Meanwhile, it’s critical to unearth clean water reserves for tap water production and consider investing in reverse osmosis systems to filter out threatening heavy metals.”

Ms. Sitang entreated the government to stand strong. “Thailand cannot shrink back, as if powerless against harms inflicted on its territory. A strong national response is essential to safeguard public health.”

In an exhibit of civic activism, Chiang Rai residents are gearing to rally on Thursday, calling for a cessation of mining activity in Myanmar. Their plan is to request embassies to take the baton and intervene.