Mainstream Dams Threaten the Mother of all Rivers

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While China is midway through the construction of a controversial cascade of major dam projects on the Upper Mekong mainstream, the lower stretch of the river shared by Thailand, Cambodia, Laos and Vietnam has so far escaped hydropower development. For the 60 million people who depend on the lower Mekong for food, income, transportation and other services, that has been good news. But now there are troubling signs that the tide is turning, as Laos and Cambodia offer up stretches of the mighty Mekong to dam builders.

In 1994, the Mekong Secretariat (the pre-cursor to the Mekong River Commission, or MRC) produced a study of “run-of-river” hydropower schemes for the lower Mekong. The study proposed nine projects that would produce a total 13,350 megawatts of electricity and displace an estimated 57,413 people, and that most of the electricity would be exported to Thailand.

IRN responded then with an analysis that stated: “The report attempts to give the impression that these projects are small dams without storage reservoirs. In fact, what is proposed is a staircase of dams 30 to 60 meter high with reservoirs covering more than 600 kilometers of the 1,800 kilometers studied. The six dams and reservoirs recommended are on a comparable scale to the Bonneville Dam on the Columbia River in the US Northwest. Such massive dams cannot be considered ‘run-of-river’ projects.”

The Mekong Secretariat study failed to adequately consider the significant impacts the proposed dams would have on fisheries throughout the Mekong River basin, such as blocking migration routes and inundating spawning grounds. According to IRN’s review, the study also ignored the downstream impacts on the Mekong Delta, failed to assess the water quality impacts of the dam cascade, and included inaccurate resettlement estimates.

Fortunately, none of these schemes got off the ground in the late 1990s. The 2001 Mekong River Commission’s Hydropower Development Strategy attributed the failure to develop mainstream Mekong dams to three factors: riparian countries’ focus on tributary projects within their national borders; the unfavorable political situation in the region; the significant costs of the projects, and the “formidable” fisheries and resettlement impacts of the mainstream dams.

The MRC Hydropower Strategy went on to note, however, that conditions were beginning to change. With increasing power demand in Thailand and Vietnam and a move away from thermal power plants, renewed interest from private developers and state-owned utilities with financial and managerial “spare capacity,” and the rising price of energy alternatives, riparian countries began to look again at damming the lower Mekong. By mid-2007, Laos and Cambodia had signed agreements for the development of four mainstream Mekong dams.

Don Sahong Dam
The mainstream Mekong dam at the most advanced stage of consideration is Don Sahong in the Khone Falls area of Laos. Mega First Corporation Berhard from Malaysia is conducting a feasibility study on Don Sahong that is expected to be completed shortly. The 240 megawatt (MW) dam would generate power for export to either Thailand, Cambodia or Vietnam. Although little information is available about Don Sahong, news reports estimate the project cost to be US$300 million.

Khone Falls is the only waterfall on the lower Mekong and is a key area for Mekong fisheries. The Don Sahong Dam, located less than one kilometer upstream of the Cambodia border, would block the sole channel that fish migrating up from Cambodia can easily pass, known as Hoo Sahong in Laos. As a result, the dam could prevent fish migrations up the Mekong River from Cambodia and Vietnam to Laos and Thailand, ultimately undermining fisheries-based livelihoods in all four countries. In fact, a Mekong River Commission 1996 newsletter noted: “The blocking of Hoo Sahong could devastate much of the most important Mekong River fisheries in Laos.”

In May, more than 30 scientists sent a letter to Mekong-region government officials expressing concern about the proposed dam’s impacts on fisheries. The letter states: “the location of this proposed dam is probably the worst possible place to site a 240 MW project since it is the point of maximum concentration of fish migration in the river that supports the world’s largest freshwater fishery.” The scientists’ letter cites a 2002 fisheries review commissioned by the MRC which determines that the construction of fish passages to mitigate impacts on fish migrations is “simply not valid for larger projects.”

NGOs from the Mekong region, East Asia, Australia, Europe and the US also sent a letter urging the Lao government to abandon its plans for Don Sahong this year. In addition to the dam’s devastating impacts¬† on fisheries, the NGOs note that it would be located just upriver from Laos’ only year-round population of Irrawaddy dolphins, likely leading to their extinction along the Lao-Cambodia border and destroying local tourism that depends on them. The Don Sahong Dam would also negatively affect people living on Don Sahong and Don Sadam islands near the proposed dam site. The Lao government has not responded to these letters of concern.

Laos proposes two more
The Lao government signed an agreement earlier this year with  a Thai company to conduct a feasibility study on the Sayaboury Dam on the Mekong River in northern Laos. The company claims the project would cost an estimated $1.7 billion and generate 1,260 megawatts of electricity for export to Thailand. The Sayaboury feasibility study would be completed before the end of 2009 and construction could begin in 2011. Very little is known about the project. The 1994 Mekong Secretariat study estimated that the project would flood 22 square kilometers of land and displace 1,720 people from five villages, although the population has surely increased since then.

And in June 2007, the Lao government approved the investigation of yet another mainstream dam, to be conducted by two Chinese companies, Sinohydro Corporation Ltd and the China National Electronics Import and Export Corporation. The 1,320 MW proposed Paklay Dam would, according to news reports, cost up to US $1.7 billion to develop. The 1994 Mekong Secretariat study said that Paklay would displace 11,780 people.

Cambodia’s Sambor Dam
The proposed Sambor hydropower project would be located on the Mekong mainstream in Kratie Province, Cambodia, just south of a 40-kilometer river island on which five villages are located. The Cambodian government has been eager to build the project for decades, but political circumstances and financial difficulties, as well as the project’s considerable environmental and social impacts, has thus far prevented them from doing so.

In November 2006, the China Southern Power Grid Company announced that its subsidiary would conduct a new feasibility study for the Sambor hydropower project. According to news reports, the company is considering two design options, both of which were first identified in 1994. A larger scheme, proposed by the Mekong Secretariat, would see a 10-kilometer long, 54-meter high dam blocking the Mekong River to create a reservoir of 880 square kilometers and generating 3,300 MW of electricity. Alternatively, a smaller scheme would create a reservoir of six square kilometers and generate 465 MW of electricity.

The company has already commenced a geological survey of the proposed site, although villagers have not yet been fully informed of the potential impacts of the project. However, some villagers have been told that if the project does go ahead, those requiring resettlement would be relocated close to a highway 20 kilometers away.

Detailed evaluation of the project’s environmental and social impacts has yet to be conducted. A recent assessment by Cambodia’s Ministry of Industry, Mines and Energy suggests that while the larger 3,300 MW scheme would have environmental impacts, the smaller scheme would not. Even hydropower consultants Tokyo Electric Power Services Co. Ltd, who have recently promoted other hydropower projects in Cambodia, expressed disbelief at this assessment of the smaller scheme.

The 1994 Mekong Secretariat study of the larger 3,300 megawatt project indicated that 5,120 people would be resettled. Both projects would also have an inevitable and massive impact on the Mekong River’s fisheries, including commercially important species such as the migratory catfish and more exotic species, such as the world’s largest freshwater stingray. In addition, IUCN identified the Sambor Dam to be a serious threat to the habitat and movements of the endangered Irrawaddy dolphin and its prey, whose territory include numerous deep water pools close to the location of the dam.

Choking the mainstream
While none of the lower Mekong dams has been given the green light yet, the rapid developments of the past six months are cause for concern. The Mekong’s abundant fisheries are of vital importance to the food supply of most of the people living in the basin. Damming the Mekong mainstream and blocking the migratory route for hundreds of fish species could have devastating consequences for the livelihoods of millions.

The governments of Laos and Cambodia now face important decisions about the mighty Mekong River’s future. Their choices will determine whether the Mekong remains the free-flowing, life-giving river that it is today or is transformed into a choked and industrialized waterway. As the Lao and Cambodian governments take decisions on these proposed lower Mekong dams, they should consider whether future fishing generations will be able to harvest the natural bounty of the river, future tourists will be able to watch playful Irrawaddy dolphins in appreciation and wonder, and ultimately whether the Mekong River will continue to be a source of pride and inspiration for the region’s people and those around the world.
This article appeared in International Rivers, World Rivers Review, Vol 22, No 2. Published in June 2007.