Stung Treng, Cambodia: The company's bulldozers came early one morning and pushed Ota Khami's wooden stilted house into muddy waters swirling towards the Mekong, the 4345-kilometre river whose roaring currents, waterfalls and gorges have long enchanted travellers and inspired explorers.
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Ota Khami's seven children and wife wept as the giant machines crushed his mango, cashew and jackfruit trees.
"We couldn't do anything – our lives were ruined," says the 55-year-old villager from north-east Cambodia.
Now, 12 months later, the land that Ota Khami says he slashed and burned in the late 1990s to make his home alongside the Sesan River near the border with Laos has been turned into a canal next to a 75-metre-high concrete wall, one of 11 hydroelectric projects being built, under construction or planned in an area known as the Mekong basin in Cambodia and Laos.
Conservationists, politicians and at least one prime minister are warning the quest for hydro power for booming urban centres in China and south-east Asia is threatening the food supply of more than 40 million people, including millions in the Mekong Delta, Vietnam's food bowl.
Kraisak Choonhavan, an environmental activist and former chairman of Thailand's Senate foreign affairs committee, calls the building of the dams "a disaster of epic proportions" that threatens to shatter declarations of unity among member states of the Association of South-East Asian Nations (ASEAN).
Vietnamese Prime Minister Nguyen Tan Dung warns that 27 per cent of his country's GDP, 90 per cent of its rice exports and 60 per cent of its seafood exports are at risk, mainly because disrupted sediment flows could destroy the integrity of the Mekong Delta.
Duong Van Ni, of Vietnam's Can Tho University, who has studied environmental factors affecting the delta, says Chinese dams have already reduced the delta's sediment by half and caused serious erosion, damage to soil fertility and mangrove forest depletion.
He warns of possible social unrest and mass migration if meddling with flows of the Mekong causes shocks like heavy floods or drought.
"There will be impacts on crops, animals and the environment with social consequences," he says. "Imagine water festival time and no water."
Fed by snowfields in the Tibetan plateau, the Mekong flows through China and Myanmar until it forms the border dividing Thailand and Laos, then on through Cambodia's vast lake system until its delta meanders through Vietnam into the South China Sea.
The Laotians call it Mae Nam Khong, the Mother of Water. The Vietnamese refer to it as Song Cuu Long, or the Nine Dragons River.
Cambodians prefer Tonle Thum, or simply Great River. Its waters are deeply imbedded in the region's economies, culture, history and livelihoods. Cambodians and Laotians eat more fish per capita than any other nationalities.
Brown with silt, the river delivers liquid dirt packed with nutrients to replenish the region's farms and paddy fields, second only to the Amazon in biodiversity.
For centuries fishermen have cast nets and drawn in hauls from the world's most productive inland fishery, accounting for up to 25 per cent of the world's total freshwater catch.
But the river has become unpredictable in recent years, rising and falling suddenly and not according to the seasons, villagers and conservationists say. Sandbars now protrude at times when before they were never there and fish stocks have dropped dramatically in some areas, villagers say.
The reason is that China has built six giant dams hundreds of kilometres upstream, conservationists say. Fourteen more are planned in China within the next decade as well as the 11 mainstream Mekong Basin dams in Laos and Cambodia.
And a total of at least 140 hydro power dams are proposed for the entire Lower Mekong River mainstream and its tributaries.
Ame Trandem, south-east Asia program director for the environmental group International Rivers, says the dam-building rush and climate change have brought the Mekong River Basin close to a "catastrophic tipping point".
An environmental study by the partly Australian-funded Mekong River Commission warns that dams planned for Laos and Cambodia would transform more than half the river into a series of stagnant reservoirs and change its landscape forever.
The dams would block fish migration routes, reduce vital wetland areas and change the habitat necessary for Mekong fisheries.
The study warns more than 100 fish species would be at risk of extinction, including the Mekong giant catfish and Irrawaddy Dolphin. Fish catches could drop by as much as 42 per cent, the study warns.
The World Wildlife Fund (WWF) says dwindling numbers of the snub-nosed Irrawaddy dolphin should ring alarm bells that all is not well.
However, Laos and Cambodia, desperate to cash in on the Mekong's hydro-power potential, have undermined a call by the Mekong River Commission for a 10-year moratorium on dam construction.
The Marxist-Leninist regime in Laos is accelerating its building of Xayaburi, one of the most controversial dams, which will produce 1285 megawatts – enough electricity to power a medium-sized city.
Most of the electricity will be sold to Thailand under an agreement signed between the dam's builder and a Thai utility company.
Laos pushed ahead with the dam despite repeated demands by Cambodia and Vietnam for further study and consultation.
Laos has also approved another dam called Don Sahong, less than two kilometres from the Laos-Cambodia border, saying it wants to become the "battery of Asia".
A Malaysian developer plans to build the dam across the Mekong's main channel, which supports year-round fish migration.
"The dam will block the only channel suitable for year-round fish migration, putting the world's largest inland fishery at risk," the WWF says in a report.
In December 2012 Sombath Somphone, a 63-year-old environmental campaigner who was critical of the dam, was detained by police in the capital Vientiane and has not been seen since. Human rights activists fear he was murdered to silence his stand on environmental issues.
Laos has a development plan that contains 72 new large dams, including nine on the lower Mekong mainstream, of which Xayaburi is the first.
Vietnamese researchers describe the region's race for hydro power as a "time bomb" for the low-lying Mekong delta, home to more than 17 million people and already under stress from rising sea levels and overpopulation.
Leading environmentalist Nguyen Huu Thien estimates the dams will cause a loss of 220,000 to 440,000 tonnes of migrating white fish a year, creating a loss of $US4 billion.
He says the loss of fish alone outweighs any benefits from the dams.
Experts have also raised concerns that if any of the dams breach there could be catastrophic break in all the downstream dams, with a 30 billion cubic metre wall of water 18 kilometres wide and 56 metres high.
Geologists also warn the Xayaburi dam is being built in an earthquake-prone location. One quake of 5.4 magnitude hit 48 kilometres from the site in 2011.
However, the region's push for hydro power has many supporters as well as critics, prompting intense debate about the dam projects.
Ulrich Zachau, the World Bank's country director for south-east Asia, argues that done properly, hydro power offers affordable and reliable access to electricity which is essential for economic growth, poverty reduction and sustainable development.
"And as hydro power is renewable energy, unlike fossil fuel-based energy, it is clean and green," he says.
Zachau says Laos' Nam Theun 2 hydro-power plan, which the World Bank and Asian Development Bank approved in 2005, has helped the country lift economic growth, increased electricity use from 16 per cent to 90 per cent of the population and reduced poverty.
However, a study commissioned by the United States Agency for International Development (USAID) to examine the region's dams found last year there are so many uncertainties that the economic impact could be from a net gain of $US33 billion to a net loss of $US274 billion.
Robert Costanza, a professor at Portland State University in the US who was lead author of the study, says dam builders should post a bond large enough to cover potential damages or the international community and neighbouring countries should pay Laos not to build any dams.
Ota Khami grew up in Phluk village in Cambodia's Stung Treng province on the Sesan River, 25 kilometres upstream from the river's confluence with the Mekong and 16 kilometres downstream from where a Chinese and Cambodian consortium is building a $US781 million dam project called Lower Sesan 2 that has engulfed his land.
Ame Trandem, of International Rivers, says there is already scientific evidence the dam will wipe out 9 per cent of the Mekong's fisheries and reduce sediment loads by 6 per cent. "The impacts this will have on food security and lost livelihoods will be far-reaching and devastating," she says.
But Ota Khami says even years before the arrival of the bulldozers at his house the river had changed, forcing his family and other villagers to turn away from fishing to less certain farming.
In 1991 Vietnam had completed its second largest dam, Yali Falls, about 100 kilometres upstream from his village in Vietnam's Central Highlands.
Ota Khami says before Yali was built there were never floods in his village, which sits on a bank of the Sesan.
"Now the waters sometimes come so high they flood halfway up our houses ... and then there are times the river almost runs dry," he says.
Ota Khami says the developers of the Lower Sesan 2 project offered him $500 for his land, which they claim he settled on after plans for the dam were announced. He denies the claim.
At night families in Phluk village huddle beside lanterns or flickering lights powered by car batteries.
As far as they know all the electricity from the giant projects that have disrupted the river upstream will be sent to power cities like Bangkok, where mega-malls and rapid development are creating an insatiable demand for ever more electricity.
Ota Khami says before the dams there was as much fish as families along the river wanted.
"Nobody went hungry and we were happy ... We could read the river by the seasons. We knew it as well as our children," he says.
