Endangered Asian elephants and Indochinese tigers still roam the upper reaches of the river within Phou Den Din National Protected Area, one of 20 national parks in Laos. This is the beauty that tourists, many Australians among them, come so far to see.

Yet this undeveloped region in northern Laos is about to be jolted into the industrial age. Three hours downriver from Nong Kiew, a scar of ochre-coloured dirt and rock stretches for kilometres: construction of the Nam Ou 2 Dam is steamrolling ahead.

''We started early this year and we'll be finished in three years,'' boasts a Chinese engineer dwarfed by a colossal concrete dam wall. Conversation is brought to an abrupt halt when his superior arrives. ''You have to leave,'' he says. ''We don't want pictures of this posted on Weibo [the Chinese version of Twitter].''

The 450 kilometre-long Nam Ou, one of the few Lao rivers traversable by boat for its entire length, will soon be severed seven times over by a 350-kilometre stretch of hydropower dams built and maintained by Chinese giant Sinohydro.

The Nam Ou 2 belongs to the first phase of the $1.95 billion project, which is expected to be operational by 2018. Details surrounding the project are scant. Even the final destination for the proposed 1146 megawatts of hydropower is unclear, although the Lao government claims the first three dams, Nam Ou 2, 5 and 6, will provide electricity for domestic consumption.

Details of the other dams have not been made public. Ultimately, the Phou Den Din National Protected Area will be partially inundated by the two northernmost dams, the Nam Ou 6 and 7, in violation of Sinohydro's own environmental policy against development inside national parks. A pristine waterway and one of the last intact ecosystems in the region will change forever.

Despite concerns of environmentalists and objections by neighbouring Thailand, Cambodia and Vietnam, the tiny, landlocked nation of Laos is following China's lead in its exploitation of the Mekong River and its tributaries.

China already has five hydropower dams operating and three more are planned for the upper reaches of the Mekong, the river that begins in the Tibetan Plateau and continues through China and five south-east Asian nations on its way to the South China Sea. Questions remain as to whether the river and those who depend on it for their livelihoods can survive.

''The government tells us that this will develop Laos,'' says 65-year-old fisherman Thongsai Chanthalangsy, speaking at his village half an hour downstream from the Nam Ou 2 construction site. ''It's not for the people,'' he continues, ''the power will mostly be sold overseas. We can't talk to the government. We have to follow what they say.''

Chanthalangsy has been advised that his home, which falls within the catchment of the planned Nam Ou 1 dam, will not be submerged, yet many other homes in his village will be.

''They will build more dams and the problems will get worse. When it's finished there might not be enough water for our gardens and not enough fish to catch. There won't be compensation. We'll have to move.''

The Mekong and its tributaries are the front line of a massive development drive by Laos' communist, one-party leadership to lift the nation from the ranks of Asia's poorest countries.

Although hydroelectric power will bring much-needed revenue to the impoverished country, many fear that dams will cost dearly Laos, and all those for whom the Mekong is a lifeblood. In Laos, Thailand, Cambodia and Vietnam, more than 60 million people depend on the Mekong for food, income and transportation.

Ground zero for the Mekong is the gargantuan Xayaburi Dam, a project led by Thai construction firm Ch Karnchang. Dynamite and heavy machinery have already blasted, gouged and scraped away entire mountainsides above both banks of the swift-flowing waters about 30 kilometres from the provincial town of Xayabury.

Steep, winding, unmade roads carry a constant procession of trucks, earth movers, workers and occasionally armed soldiers to the expansive site. The $3.4 billion price tag of 810-metre-long and 32-metre-high Laos-Thai mega dam is being footed by a conglomerate of six Thai banks.

On its completion in 2019, around 95 per cent of the hydropower dam's 1260 megawatts will be exported to Thailand. This is almost a third of the power generated by the 16 major dams of Australia's Snowy Mountains Scheme, built over a period of 25 years to generate around 3700 megawatts.

Along with the immediate environmental impact of a project of such magnitude, hundreds of villagers have been resettled to make way for the dam.

At the new village, Natornatoryai, close to the construction site, teacher Khao Thevongsa, 28, is dissatisfied with the location, with its steep hills of barely arable land and the constant stream of traffic to the site.

She hopes that the dam may become a tourist attraction in its own right. ''We have to start from zero,'' she says, ''but when the dam is finished maybe tourists will come here to see it and we can earn more money.'' Almost every answer to a question begins with, ''We don't have a choice.''

About 300 were first shifted to Natornatoryai, which is about 35 kilometres from the river. ''The old people didn't want to move here,'' says 63-year-old Khamkeo Daovong as her daughter-in-law and child play on her concrete floor. ''I was born near the river and so were my parents. Many people cried when they saw their new homes.''

Daovong complains that her house was unfinished when she moved in. The mismatched cinder-block and terracotta bricks were paid for out of her own pocket to keep out the dust and wind. Compensation in the form of rice and about $16.40 in cash per month dried up after one year instead of the promised three.

''I was given pigs and ducks to raise, but it's very difficult to make money. I used to pan for gold, but now I just do nothing.''

According to non-government organisation International Rivers, about 25 families have already left the village to return to the river to fish, tend their river bank gardens and pan for gold.

For those who live in Laos, open opposition to the dam is unthinkable. The Lao regime has a history of ruthlessly silencing dissent.

On December 15 last year, Sombath Somphone, 62, a prominent campaigner for the environment and the rural poor, and a champion for sustainable development, was abducted from a police roadblock by two unidentified men in the nation's capital, Vientiane.

Somphone, the 2005 recipient of the Ramon Magsaysay prize, often referred to as Asia's Nobel prize, has not been seen or heard from since. The Laos government denies any involvement. The official explanation for his disappearance was a ''business dispute'', although the activist has no business interests.

The incident brought rare international attention to Laos, as then US Secretary of State Hillary Clinton and her successor, John Kerry, led calls for a thorough and transparent investigation into Somphone's whereabouts and wellbeing.

International calls to the Laos government for action and information on Somphone remain unheeded. In a recent statement by New York-based watchdog Human Rights Watch, Asia director Brad Adams accused the Lao government of direct involvement in the activist's disappearance.

''Lao authorities have not answered the simplest questions, such as why, if Sombath was kidnapped, did the police at the scene do nothing to protect him,'' Adams said. ''The absence of any real investigation points to the government's responsibility.''

The reasons for the activist's disappearance are unclear. But Somphone's abduction has worsened an already fearful climate in Laos' environmental grassroots organisations.

Land rights and enforced disappearances aside, dams on the Mekong have serous ramifications far beyond the borders of Laos. The Xayaburi Dam is the first of 11 dams planned for the Lower Mekong River, nine of which are in Laos. Environmentalists have already blamed China's five Mekong dams, as well as drought, for some of the lowest water levels seen on the river in 50 years. China denies it is responsible.

On top of providing crucial sediment for arable land downstream, the Mekong sustains the world's largest inland fishery, with 877 species. According to conservation group Great Rivers Partnership, this supplies an industry worth between $3.84 billion and $6.89 billion.

Fish are a foundation of regional food security. In Cambodia, 80 per cent of the nation's animal protein is provided by freshwater fisheries. Alarmingly, a study of the proposed 11 Lower Mekong hydropower dams by the International Centre of Environmental Management concluded that the dams would reduce fish numbers by 26 per cent to 42 per cent.

Regional famine is a worst-case scenario. Claims by the Lao government and Xayaburi dam officials that fish ladders will allow safe passage for migratory Mekong fish species have been met with great scepticism.

Organised dissent to the Xayaburi Dam has mainly come from Thailand. A flotilla of Thai fishermen and villagers who worked the Mekong travelled to Vientiane to protest during the Asia-Europe Meeting.

In April, delegates from eight Thai provinces on the Mekong were joined by protesters from Cambodia as they occupied the entrance to the headquarters of the dam's construction company, Cr Karnchang, one of the dam's financiers.

Although limited at present, opposition to dams on the Mekong may be about to rise rapidly as more dams are built and their impact becomes apparent. Beyond street and river protests, there are rumblings at the highest levels of government that threaten to become a diplomatic stoush.

Should the worst fears of environmentalists materialise, countries downstream from the dams stand to bear the brunt of any damage to the Mekong's ecosystem. Although Vietnam and Cambodia have plans for their own hydropower projects, they have already objected to the Xayaburi Dam through the Mekong River Commission, of which Thailand and Laos are also members.

Both countries have argued that work on the Xayaburi Dam breaks an agreement forged in December 2010 that no dams would be built until studies on negative trans-boundary environmental impacts were completed.

Vietnam has called for a 10-year moratorium on all Mekong dams. Such concerns have been brushed aside by Lao Deputy Minister for Energy and Mines, Viraphonh Viravonghas, who claimed the extensive construction is merely ''preparatory work''.

''Laos has simply ignored the requests repeatedly made by Cambodia and Vietnam to study the trans-boundary impacts of the dam,'' says Ame Trandem, south-east Asia program director at International Rivers.

''The Mekong is becoming the testing grounds for new technologies, which may prove to have disastrous effects. The entire future of the river's ecosystem is at stake. The Xayaburi Dam is just the tip of the iceberg.''

Dave Tacon is an Australian journalist based in Shanghai.