'Catastrophic' dam

Work has started on the Lower Se San 2 Dam, a 400-megawatt hydropower project whose vast reservoir will force thousands to move.

For 37-year-old rice farmer Pa Tou, the future looks bleak. The relocation site set aside for them is wholly unsuitable, he complains. There is no irrigation, it is miles from the river and the ground is either rocky or covered with trees. And at this stage it has no schools, no health clinics, no pagodas and no roads.

“Everyone here worries how we will make a living,” he says.

Fish highways

Scientists share Pa Tou's pessimism about the $800-million Lower Se San 2 Dam, but note that its effects will be felt far beyond Srekor. That is because the Se San River, which the dam will block, is a vital breeding ground for fish in the region.

Dr Eric Baran, the senior research scientist at WorldFish, an NGO focused on food security, describes the Se San River as one of four “fish highways” in the Lower Mekong Basin. Along with the Sre Pok River and the Se Kong Rivers, both of which flow into the Se San, this collection of three tributaries is known as the 3S network and is where migratory fish breed.

The fourth highway is the Mekong, into which the 3S network empties.

The Lower Se San 2 Dam, which will be built downstream of the confluence of the Sre Pok and Se San rivers, will completely block two of these fish highways. By the time its 8-kilometre-long wall is finished, only the Mekong and the Se Kong will remain open to the 40 percent of the fish in the Mekong Basin that are migratory.

Unable to breed, the replacement generations of fish will simply not be born, says Baran. He estimates that the Lower Se San 2 Dam will cut the annual fish catch of the entire Mekong Basin by 9.3 percent.

“So it's 9.3 percent of 2.1 million tons – which is a gigantic amount,” Baran says.

That amount of lost catch – around 200,000 tons per year – is more than Australia's annual marine catch.

Regional effects

The Lower Mekong Basin is home to tens of millions of people, many of them poor. For Cambodia, whose per capita freshwater fish consumption is higher than any other nation, hydropower dams will affect food security.

“People have become very reliant on [fish, which are] also by far the first source of animal protein,” says Baran. “[Fish] represent 81 percent of the animal protein consumption in the country.”

A paper published last year in the respected US journal The Proceedings of the National Academy of Sciences warned that the region's scramble for hydropower would have a “catastrophic” impact on the Mekong Basin, which is the world's richest freshwater fishery.

The researchers calculated that plans to build more than 70 dams in the Mekong River Basin would be disastrous. Baran, who co-wrote the paper, says the Lower Se San 2 Dam will be the most damaging of any tributary dam.

Global concern

The research has spurred global concern. Last year, the then US Secretary of State, Hillary Clinton, urged Mekong nations not to make the same mistakes regarding dams as the US had made.

International Rivers, a campaigning NGO, predicts the Lower Se San 2 Dam “will have a costly, catastrophic impact on the Mekong River's fisheries and biodiversity”.

“All of the research that has come out has proven that the impact of the dam will be much greater than the benefits of the project,” says Ame Trandem, the Southeast Asia program director for International Rivers.

Trandem says there will be agricultural losses too, with the Lower Se San 2 Dam calculated to block up to 8 percent of sediment flows on the Mekong. These nutrients are vital for fertilizing the fields of countless thousands of subsistence farmers.

“So this is something that will affect all of the rice fields in Cambodia going down to the Mekong Delta in Vietnam as well,” she says.

The expected effects of the Lower Se San 2 Dam are so severe that in late 2011 a group of 29 international scientists with expertise in fisheries wrote to Cambodia's Prime Minister Hun Sen warning that the dam would harm hundreds of thousands of people in Cambodia, Vietnam, Thailand and Laos.

The letter stressed their “sincere concern” that this dam would cause “increased poverty and malnutrition over a wide area in Cambodia, thus working against the Cambodian government's development plans for the nation, including its efforts to achieve UN Millennium Development Goals”.

The scientists reportedly did not receive a response.

Government silence

Cambodia and its neighbors certainly need more power: three-quarters of Cambodians lack access to the grid, and power cuts in cities and towns are common.

Although hydropower is a source of clean electricity, its detractors say the social and environmental costs of large projects like this one outweigh the benefits. They say small schemes such as solar, wind and micro-hydro dams that generate energy locally are better because they cost less, lose less electricity in transmission and have fewer negative effects.

Yet, Cambodia has only a handful of such projects and they do not appear to be part of the government's energy policy. The Minister of Industry, Mines and Energy, Suy Sem, declined to be interviewed for this article, as did another senior ministry official. Questions emailed to the minister were not answered.

But media reports consistently show the government favors projects like hydropower dams and coal-fired power stations. More are likely to go ahead. On May 9, the Cambodia Daily newspaper said two more planned dams on the 3S network had been deemed economically feasible, moving them a step closer to approval. One would be a 370MW dam on the Se San River; the other a 100MW dam on the Sre Pok River. The first would flood 40 villages alone.

Meanwhile the Cambodian government has plans to build a hydropower dam on its stretch of the Se Kong River, which rises in Laos. Baran says that would block the region's third fish highway, leaving the Mekong mainstream as the sole route for migratory species, further harming fish stocks. The rush to hydropower risks inflicting profound and irreversible damage to many more people than the residents of Srekor village.