Specter of dams and diversion looms over Southeast Asia’s Salween River

MAE HONG SON, Thailand — The shores of Myanmar became visible from Sob Moei village in northeastern Thailand as the morning mist rises over the Salween River, the flowing water the only border between Thailand’s Mae Hong Son province and Myanmar’s Kayin state.

Flowing nearly 3,300 kilometers (about 2,000 miles) from Tibet, south through China and Myanmar, before joining the Andaman Sea, the Salween River is Asia’s longest free-flowing river.

Home to more than 200 species of fish, a quarter of which are estimated to be found nowhere else in the world, and irrigating vast tracts of farmland, the Salween is a vital resource that provides food security, livelihoods, as well as drinking and bathing water to largely Indigenous communities across three countries.

Devoid of the hydropower dams that have choked the Mekong River and its tributaries, the Salween unites farmers and fishers in Thailand and Myanmar more than it divides them. But planned dams on the Myanmar stretch of the river mean its free-flowing nature is far from guaranteed.

“We get our food from the river, so if the Salween River is dammed or developed, it will definitely impact our families,” said Naw K’nyaw Paw, secretary-general of the Karen Women’s Organization, speaking at a protest against dams at Sob Moei on March 14.

At least 20 dams have been proposed or planned along the Salween, with 13 in China and seven across Myanmar. But many of these projects were conceived decades ago and appear to have stalled. China, for its part, held off from building dams before finally dropping any mention of damming the Salween in 2016.

In Myanmar, the situation looked very different until the 2021 military coup that saw General Ming Aung Hlaing seize power from the democratically elected civilian government, escalating conflict has spread across the country. Since then, the military junta is believed to have killed at least 6,000 people, arbitrarily arrested more than 20,000 and displaced more than 3.5 million people since 2021. This is along with the junta bombing schools, hospitals and civilian populations as numerous factions, including ethnic armed groups and people’s defense forces, which formed to resist the coup, fight to regain and retain control in an increasingly fragile and fragmented state.

Chinese and Thai investors who had been eyeing opportunities to dam the Salween River have been waiting for the dust to settle, leaving the seven planned dams in limbo as conflict rages on. Myanmar’s military junta was estimated, as of March 2025, to control as little as 32% of the country’s townships, with big gains being made by rebel factions and ethnic armed groups. This, experts warn, could be the deciding factor as to the fate of the Salween River.

Myanmar’s gamble on hydropower along the Salween

Three of the seven dams planned on the mainstream of the Salween River in Myanmar are in Shan state: the 1,400-megawatt Kunlong Dam, the 1,200-MW Nao Pha Dam and the 7,000-MW Mongton Dam. All three lie in parts of the state controlled by the United Wa State Army (UWSA), one of the most powerful armed factions in Myanmar and one that enjoys close ties to China.

The northernmost dam, the Kunlong, has already seen an environmental impact assessment (EIA) produced and was moving ahead with Hanergy Holding Group and Powerchina International Group listed as developers. The project was approved in 2010 and led to the displacement of some 30,000 villagers in 2013, only to peter out. The project now seems dormant.

Meanwhile, the Nao Pha Dam, approved in 2009 as part of a double-dam deal with Chinese state-owned enterprise Hydrochina, could still go ahead; Hydrochina continues to work on the 225-MW Mantong Dam, being built on a tributary of the Salween as part of the same 2009 agreement.

The Mongton Dam, meanwhile, is a joint venture signed in 2010 by EGAT International, a subsidiary of the Electricity Generating Authority of Thailand, and China Three Gorges Corporation and Sinohydro. But while initial construction began as early as 2007 and an EIA was submitted in 2014, it’s still unclear whether this EIA was ever approved. EGAT faced significant criticism for its involvement in the project, which played a role in the displacement of an estimated 300,000 people across southern Shan state.

The remaining four planned dams would be located in states that are home to Karen and Karenni ethnic groups that have largely allied against the military junta following the coup.

The 4,000-MW Ywathit Dam was planned for Kayah state, now controlled by the Karenni Army. The 792-MW Dagwin and 1,360-MW Hatgyi dams are proposed to be built in neighboring Kayin state, currently under control of the Karen National Union, which itself boasts a powerful army that has vehemently opposed both the military junta and the damming of the Salween. The proposed site for the 5,800-MW Weigyi Dam lies on the border between Kayah and Kayin states.

Transborder resistance

“Today, many have braved airstrikes to come here,” said K’nyaw Paw, speaking on March 14 at the Thai-Myanmar border. “The Karen armies are strong, some of the biggest [in Myanmar], so the river remains free-flowing because the armed forces here will defend it. But up north, the situation is different, we don’t know whether the militaries in Shan state will allow a dam to be built on the Salween and if it does, it will have a big impact. If dams are built to the south, many villages would be inundated and at risk of flooding.”

Across Shan, Kayah, Kayin and Mon states, through which the Salween flows, conflict, civil war and violence have long made life incredibly difficult for the Indigenous communities that make up the majorities of each state, said Pianporn Deetes, Southeast Asia campaigns director at International Rivers, who has documented attempts to dam the Salween for decades.

“People have been struggling just to survive, it’s already difficult, so if the dam is built, if the river turns into a reservoir, if their farmland and their refuge sites are taken or submerged, there’ll be more humanitarian impacts on the local population in Myanmar,” she said.

Veteran Thai environmentalist and Goldman Prize winner Niwat Roykaew, speaking in Sob Moei village on March 13, warned that the Salween could suffer the same fate as the Mekong if transboundary efforts to protect it fail.

“If we compare our rivers, the Mekong is dead already because of so many dams that have strangled the river,” he said. “I feel good that there are no dams on the Salween River yet, but I came here today to share the grief and sadness of the Mekong River — so don’t let them build dams on this river.”

A river under siege

While these hydropower projects are largely focused on the Myanmar side, the impacts promise to transcend borders and make themselves felt in Thailand.

One such project is the Hatgyi Dam, planned to be built some 47 km (29 mi) south of Sob Moei village where protesters gathered in March, has also attracted significant attention from EGAT, which is a co-developer in the $2.6 billion project. Protests have flared up periodically throughout the 2010s, but the Myanmar coup in 2021 appears to have delayed the development of Hatgyi.

Should Hatgyi go ahead, said Hannarong Yaowalert, president of the Foundation for Integrated Water Management, then the whole of Sob Moei village would be submerged under the dam’s reservoir.

“The Moei River will be cut off, a huge stretch of river would be affected if they build the Hatgyi Dam, but the EIA that was done to push for the dam doesn’t identify any impacts on the Moei River, so of course people are concerned,” Hannarong told Mongabay on March 14. “The floodwaters will consume Sob Moei [village] for sure, the people here won’t be able to continue fishing or farming, they won’t have access to clean water for drinking or bathing, and they’ve been offered no compensation to speak of, not even about relocation.”

But Thailand’s interest in the Hatgyi Dam runs deeper: the dam looks set to play a part in a larger Thai infrastructure project that promises a more direct impact on largely Karen communities across northern Thailand.

The Yuam River Diversion project is nothing new; it’s been floated, examined and studied for more than 20 years. It aims to pipe nearly 1.79 billion cubic meters (473 billion gallons) of water annually from the Yuam River, one of the Salween’s key tributaries, through roughly 62 km (39 mi) of tunnels that will result in the clearance of 582.68 hectares (1,440 acres) of forest — including that in Mae Ngao National Park — into Hok district in Thailand’s Chiang Mai province.

From there, the diverted water will be pumped into the Ping River and flow south into the Bhumibol Dam’s reservoir, where it can be stored and used as needed for irrigation across the Chao Phraya Basin, which accounts for roughly 30% of Thailand’s rice production. But diverting water to the rice fields of Chao Phraya would come at the cost of depriving Karen communities that depend on the Salween and Yuam rivers.

The first phase of the project will see the Yuam River dammed and water pumped from it into the Bhumibol reservoir, but the second phase would rely on the Hatgyi Dam being built to pump water from the Salween, through the Yuam River, to the Chao Phraya Basin.

Whose water is it anyway?

“The Thai government has tried to push for the Yuam River Diversion project, but we firmly oppose it, we’re fighting it with facts,” said Sathan Chiwawichipong, coordinator of the Yuam, Ngao, Mae, and Salween River Basin People’s Network. “It will create a range of environmental problems, it’ll destroy livelihoods, society and culture, as well as cause economic problems across the region.”

Burirat Wongburi, chief of the Bureau of Project Management at Thailand’s Royal Irrigation Department, told Mongabay via email that the diversion project will cost 170.6 billion baht ($5.2 billion), excluding private sector return and corporate income tax, but that no private sector developer is attached to the project.

The project will increase the water supply to the Bhumibol Dam, providing the Chao Phraya Basin with water for agriculture, tap water, ecological preservation and electricity generation, Burirat said. The figure of 1.79 billion m3, he added, is an average drawn from data produced by the Yuam River Basin Monitoring Station from 1971 to 2015. This equates to 62% of the 2.85 billion m3 (753 billion gal) he calculated as the Yuam River’s average annual runoff volume.

In terms of affected communities, Burirat told Mongabay that 29 people will lose land to the project, while 16 villages in a 0.5-km (0.3-mile) radius and 30 villages beyond that will be affected. But he didn’t say whether that includes Indigenous communities who are expected to lose access to the river if the project proceeds.

Diverting water from the Yuam River to the Chao Phraya Basin will generate 18.5 billion baht ($567 million) and increase the amount of land available for cultivation in the dry season by some 256,000 hectares (about 633,000 acres), according to Burirat. He said some 70,000 farming households could expect a 155,444 baht (about $4,760) average increase in income annually as a result.

Burirat didn’t explain how these figures were generated or provide any supporting documentation.

“You shouldn’t divert more than 30% of a basin’s water to another basin,” said Pianporn of International Rivers. “When we calculated, based off the existing data, it seems like more than 80% of the Yuam Basin’s water will be diverted, which doesn’t make any sense.”

She also added that at least 36 communities are set to be directly affected by the project, but that many aren’t counted because they lack legally recognized land tenure.

The 2019 EIA process was fundamentally flawed, Pianporn said, because it excluded local communities by only consulting them in Thai, leading to some villagers being photographed by consultants without realizing until the EIA was published. Even then, affected communities were required to pay 20,526 baht (roughly $630) to get a single photocopy of the document.

“Their way of looking at this issue is an outdated, almost authoritarian way of looking at natural resources,” Pianporn said. “It’s not inclusive and it’s not respectful to the customary rights of Indigenous people.”

These discrepancies snowballed until Jan. 19, 2024, when the Chiang Mai Administrative Court accepted a complaint against the project and its developers, halting progress until the complaint is resolved.

For Pianporn, the lawsuit is just the beginning. She said greater awareness of the myriad threats posed to the Salween River Basin would spur more opposition to these projects within Thailand.

“This is one of the last free-flowing rivers in the world, it’s still in natural condition, so why don’t we protect it?” she said. “Why don’t we want to make it permanent protection for the next generation?”

Banner image: Boats sporting “No Dam” parade down the Salween River along the Thai-Myanmar border in March 2025. Image by Gerald Flynn / Mongabay.

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Isabel Esterman Editor

This story first appeared on Mongabay

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