Hundreds of villagers, Indigenous leaders, environmental defenders, monks, and civil society activists recently completed a six-day Peace Walk along northern Thailand’s Kok River to demand urgent action against worsening water contamination. Their message was clear: the river that has sustained communities for generations is becoming increasingly unsafe, and stronger action is needed to stop transboundary pollution before irreversible damage is done.

The Kok River originates in Myanmar’s Shan State before flowing through Chiang Rai and Chiang Mai provinces and eventually joining the Mekong River. For communities living along its banks, the river provides drinking water, irrigation, fisheries, transportation, and cultural identity. Today, however, many residents fear that these lifelines are under threat from heavy metal contamination linked to mining operations upstream in Myanmar.

The Peace Walk has become one of the largest recent demonstrations calling for accountability over pollution affecting the Kok, Sai, Ruak, and Mekong rivers. Participants urged the Thai government to strengthen cross-border cooperation, investigate the source of contamination, and protect communities whose livelihoods depend on healthy river ecosystems.

A Growing Transboundary Pollution Crisis

Concerns over the Kok River have intensified following reports of elevated concentrations of heavy metals, including arsenic, in rivers flowing from Myanmar into northern Thailand. Environmental groups and local communities have linked the contamination to expanding rare earth and mineral mining operations in Myanmar that are reportedly financed by Chinese investors.

The issue extends beyond environmental degradation. Farmers rely on river water to irrigate crops, while fishing communities depend on healthy aquatic ecosystems for food and income. Public health authorities have also advised caution regarding the consumption of aquatic animals from contaminated rivers because of heavy metal exposure.

Civil society organizations warn that contamination now affects not only the Kok River but also the Sai, Ruak, Salween, and Mekong rivers. According to the NGO Coordinating Committee on Development (NGO-COD), turbidity along sections of the Thai-Myanmar border has increased dramatically, while arsenic and lead contamination have exceeded recommended safety levels in several communities.

Because these rivers cross national boundaries, downstream communities often bear the environmental consequences of activities occurring beyond Thailand's jurisdiction. Environmental advocates argue that stronger regional cooperation between Thailand, Myanmar, and China is necessary to investigate pollution sources, improve monitoring, and prevent further contamination (OHCHR, 2025).

Communities Demand Accountability

Public concern has grown alongside frustration over the perceived lack of effective action.

On 6 July, members of the People's Network to Protect the Kok, Sai, Ruak, and Mekong Rivers marched toward the Chinese Consulate-General in Chiang Mai to deliver a petition urging China to regulate Chinese companies operating mines in Myanmar. Protesters argued that mining activities have contributed to heavy metal contamination affecting millions of people living downstream.

Before the demonstrators reached the Consulate-General, however, they faced a police blockade.  A confrontation occurred when police tried to seize a protest banner carried by one of the demonstrators, leaving two protesters injured. One has a broken arm, and another has a dislocated shoulder. The protesters filed a police complaint alleging excessive use of force, while the police maintained that officers acted in accordance with legal procedure. One of the injured protesters, Wisarut Srichan, is also considering filing lawsuits against the police. 

Two days later, civil society organizations gathered outside the Chinese Embassy in Bangkok to demand action regarding the water contamination and condemn the police response in Chiang Mai. They called for an independent investigation into the use of force against protesters and urged authorities to identify investment networks and business operations responsible for environmental harm and human rights violations.

Environmental Defenders Under Pressure

Protesters in Chiang Mai said they did not expect a confrontation, as the march was small and they had already informed the police beforehand. But physical violence is not the only threat faced by environmental activists in Thailand.

Human rights organizations have documented increasing use of Strategic Lawsuits Against Public Participation (SLAPPs) against community leaders, journalists, researchers, and activists who speak out against environmental impacts of development projects. Such lawsuits often impose significant financial and psychological burdens even when the charges are eventually dismissed.

One widely cited case involved environmental defender Sumeth Rainpongnam, who faced a 50-million-baht lawsuit while advocating for community environmental rights. Rights organizations argue that these cases discourage public participation and make it more difficult for affected communities to raise environmental concerns.

Indigenous Communities Protecting Rivers

For Indigenous communities in northern Thailand, protecting the Kok River is inseparable from protecting their lands, livelihoods, and cultural heritage.

Karen and other Indigenous communities have long resisted projects they believe threaten forests and river systems. In Omkoi District, Karen villagers challenged a proposed coal mining project, arguing that environmental impact assessments failed to adequately consider Indigenous knowledge and local ecosystems. Communities have also opposed the Yuam–Salween Water Diversion Project, citing concerns over its potential impacts on forests, fisheries, and water resources while questioning whether affected communities were meaningfully consulted during the approval process.

These campaigns reflect a broader understanding of environmental stewardship. For many Indigenous peoples, rivers are living ecosystems that sustain culture, food systems, and future generations rather than simply natural resources to be exploited.

Participants in the Kok River Peace Walk emphasized that communities who have lived alongside these rivers for generations possess valuable ecological knowledge that should guide conservation efforts. They called for stronger recognition of Indigenous land rights, meaningful community participation in environmental decision-making, transparent environmental monitoring, and greater protection for environmental defenders.

As northern Thailand continues to confront the impacts of transboundary pollution, many residents argue that protecting the Kok River requires more than emergency responses. It demands sustained regional cooperation, corporate accountability, and greater recognition of Indigenous communities whose stewardship has long helped safeguard the region's rivers.

For those who completed the Peace Walk, protecting the Kok River is ultimately about more than preserving a waterway. It is about defending public health, cultural survival, and the rights of future generations to inherit rivers that remain safe, living, and free from contamination.