Executive Summary

The Sesan, Srepok and Sekong (3S) river basins currently stand at a crossroads. With more than 20 hydropower projects already built or under construction on the 3S rivers, plans to build 26 more dams threaten the rivers that are shared between Vietnam, Cambodia and Laos. Vietnam's hydropower development has been most extensive to date and has already taken its toll on the health of the Sesan and Srepok basins in the Central Highlands of Vietnam and downstream in northeastern Cambodia. Despite the harm these projects have had on the rivers' biodiversity, fisheries and the livelihoods of tens of thousands of affected people, Cambodia is now pursuing ambitious plans of its own to push forward development of hydropower projects along the 3S rivers, and Laos is in the process of developing its own generating capacities on the Sekong.

The 3S river system is a major tributary of the Mekong River, and the basins are widely recognized for their biological importance, rich ecosystems and key fish migration routes. Millions of people's lives are closely connected to these rivers, and their rich natural resources support the livelihoods of fishers, farmers and those who make a living by collecting non-timber forest products. More than 20% of the area has been designated as protected areas, including the Lumphat Wildlife Sanctuary and the Virachey National Park in Cambodia. Additionally, many of the basin's deep pools have been recognized as Fish Conservation Zones, as the three rivers support diverse fish and aquatic resources. However, current plans to develop large-scale hydropower projects in Cambodia, and the on-going development and expansion of hydropower in southern Laos and central Vietnam, threaten to drastically alter the ecology of the rivers. This is likely to have devastating impacts for those whose livelihoods are connected to the basin and its resources.

Map of the 3S Rivers Basin

Over recent years, electricity demand in both Vietnam and Thailand has risen sharply, while demand in Cambodia and Laos has also continued to climb, though at a slower rate. This has led to power shortages in all four countries, but also the realization that untapped water resources in Cambodia and Laos may be utilized to generate power both for domestic use and for the region. In addition to the policies and strategies of these countries to meet their own domestic needs and benefit from power sales to neighbours, external actors are also playing a key role in the development of hydropower in the area. Due to a lack of local capacity in Laos and Cambodia to develop large-scale hydropower, both foreign private and state-owned companies have moved into the picture and are developing projects under lengthy Build-Operate-Transfer agreements. In addition, international financial institutions such as the Asian Development Bank are providing support to develop links in regional power connection.

The construction and operation of existing large-scale hydropower dams in the upper reaches of the 3S rivers in Vietnam has already had severe negative impacts on downstream communities in both Vietnam and Cambodia through decreased fish stocks, erratic water fluctuations, and changes in the quantity and quality of water. These combined impacts have made it more difficult for people downstream to meet their daily food and income needs. There is now growing pressure to construct more than 26 new hydropower projects in the 3S basins, threatening sections of the rivers which are still largely intact. If built, these dams will alter the basins' natural resources through changes in water flows, water quality, land use and forest cover, blocking important fish migration routes and altering the aquatic habitat required for the spawning and feeding of fish. This in turn could disconnect people from their traditional livelihoods and forms of resource management, which would have serious economic and social implications on future environmental sustainability, landscape quality and biodiversity. Due to the close vicinity of many of these planned projects to the Mekong River and the important role the 3S rivers play in maintaining the Mekong River's abundant fisheries and nutrient rich sediment flows, the impacts of some of these projects are likely far-reaching and particularly destructive to the Mekong River mainstream.

The Sesan River is already heavily dammed in Vietnam, and although hydropower has yet to be developed on the Cambodian side of the border, there are two projects currently at the feasibility stage, in addition to the 400 megawatt (MW) Lower Sesan 2 Dam that was approved in early 2011. The Sekong River is still largely free-flowing, though Laos has plans for 22 large-scale hydropower developments along its course in the south of the country. Additionally, it was announced in late 2011 that Cambodia was considering the feasibility of a dam on the Lower Sekong on the Cambodian side of the border. On the Srepok River, a number of dams are now under construction and operational in Vietnam, and two projects are at the stage of feasibility study in Cambodia.

This report will focus on the largest hydropower projects proposed, planned and approved on the 3S rivers within Cambodia. They are:

  • The Lower Sesan 2 (400 MW), Lower Sesan 1/5 (96 MW) and Lower Sekong (190 MW) hydropower dams, which are being developed or studied by the Vietnamese state power company, Electricity of Vietnam (EVN).
  • The Lower Srepok 3 (300 MW) and the Lower Srepok 4 (220 MW), both of which are under feasibility study by the Chinese state-owned company, Huadian.
  • The Lower Sesan 3 (375 MW) which is being studied for feasibility by, Korea Cable Co. Ltd. (KTC), a Korean company.

In total, the six dams discussed in this report have a combined potential capacity of over 1,500 MW. There are also a number of smaller dams planned for tributaries of the 3S rivers, such as the Prek Liang 1 (64 MW) and Prek Liang 2 (64 MW), which are located on the O'Tapob tributary of the Sesan River. These smaller dams are not covered by this report.

A man traveling down the Sesan River. Photo: TERRA

Information related to all of the projects covered in this report has proved difficult to access. This is with the exception of the Lower Sesan 2 Dam, as this project has been subject to much debate, and an environmental impact assessment (EIA) was first made public in mid-2008. As the first large-scale dam to be approved in the northeast of Cambodia, the Lower Sesan 2 has attracted considerable attention due to concerns about its potentially major negative environmental and social impacts. The dam is expected to flood an area of at least 334 km2 and lead to the relocation of thousands of families. It is reported that the final approval of the dam in early 2011 was pushed through after the Vietnamese Government pressed Cambodia to hasten the approval process. Information on the other dams has at times been extremely difficult to obtain, and a large amount is sourced from media reports rather than official documents and statements, as these are not publicly available. It is known, however, that the Lower Sesan 3 threatens to flood an even larger area than the Lower Sesan 2 (more than 420 km2), and that the Lower Srepok 3 and 4 will both be located in protected areas and will also create potentially huge reservoirs. These projects, as well as the Lower Sekong dam, have not yet reached the EIA stage and local communities have yet to be properly consulted.

As none of the proposed large-scale hydropower projects in the 3S area of Cambodia are yet to be constructed, it is still not clear what the full extent of the impacts are likely to be. However, several studies have raised concerns that the projects as currently proposed are likely to have serious and far reaching social and environmental consequences. Future scenarios can also be extrapolated from the lessons learned and impacts experienced in the 3S region due to the Yali Falls dam and other hydropower projects already constructed and operating upstream in Vietnam. This includes drastically reduced fish stocks, changes in the quality and quantity of water flows, and unpredictable surges that have resulted in destruction to property and even loss of life. Cambodia's proposed 3S dams are all located in relatively flat areas, which means the reservoirs created by these projects are likely to be extremely large. The flooding caused by these reservoirs will inundate a huge amount of land and lead to forest and habitat loss, causing serious challenges to the area's biodiversity and local people's livelihoods. They will also claim the agricultural and residential land of thousands of Cambodians, including a sizable population of indigenous people. The exact impact of blocking fish migration on the Sesan and Srepok Rivers is still disputed, but it is clear that this will cause a number of species to disappear entirely from upstream of the dams. This has implications for tens of thousands who rely on fisheries for their livelihoods, both upstream and downstream. A number of scientists have claimed that the dam will interfere with fish migrations as far away as the Tonle Sap Lake and the Mekong Delta in Vietnam, however, the Cambodian Government disputes this claim.

In order to maintain the impressive growth rates of the last decade and capitalize on private sector interest in investing in Cambodia, legal and regulatory processes are often over-looked or only partially implemented. Both inside and outside the hydropower sector, there are numerous examples of projects that have been approved in the absence of an EIA, or when the EIA process is still on-going. In other cases, such as the Lower Sesan 2, although the EIA was completed in a timely manner and for the most part in compliance with Ministry of Environment standards, the final product was far below international standards. This is despite the fact that this is one of Cambodia's largest foreign investment projects and is to be developed by a company with decades of experience in the hydropower sector. After initially signing a memorandum of understanding with the Cambodian Government to study the feasibility of the project in 2007, the company went on to commission an EIA during the first half of 2008. The process of consultation was criticized by a number of civil society organizations and members of affected communities, as for the most part only those in close proximity to the actual dam site were consulted, and many of those who were consulted felt that they were not given adequate information. The EIA report published in 2008 was viewed by a number of observers as taking inadequate consideration of impacts on fisheries beyond the project area, and failed to adequately consider the cumulative impacts of the various hydropower projects proposed for the region. After several rounds of minor revisions, the EIA was officially approved in June 2010 and the project was approved in early 2011.

Traditional fish traps used on the Srepok River

The process and quality of environmental impact assessment in Cambodia has been subject to criticism for a number of years, but there are now on-going discussions and activities that aim to improve capacity of officials in monitoring EIAs and also to develop this area of Cambodia's legal framework. However, there is still much work to do, especially in terms of raising awareness of the private sector and some officials and government ministries about the importance of high quality EIAs and full public participation. As stated by a Director from Cambodia's Ministry of Environment: "[t]he need for environmental assessment in Cambodia is still widely considered as secondary to the need for development. The significance of EIAs is not fully recognized by, for example, many of the government ministries responsible for infrastructure or industrial and agricultural development."1

Aside from the policies and agendas of the governments and developers discussed here, there are a number of additional actors with a stake in the development of hydropower in the wider 3S area. The Asian Development Bank (ADB) has been engaged in the Mekong region for a number of years, during which time it has supported a number of projects in Cambodia, Laos and Vietnam related to hydropower development and power transmission. This includes studies in the 3S region in 1999 and 2008, and funding for feasibility study of the Sesan 3 dam in Vietnam. Through the Greater Mekong Subregion (GMS) Program, the ADB is now supporting development of transmission lines to facilitate regional power sharing. This includes support for preparing a high voltage line connecting southern Laos to central Vietnam. This transmission line will provide the connection between southern Laos' extensive proposed network of hydropower plants and the Central Highlands of Vietnam. The ADB also has also funded Technical Assistance (TA) for power trading in the region, which aimed to update the regional master plan for power trade amongst the GMS countries.

Although the ADB may no longer be directly connected to any dam projects in the 3S region, its decision to support these transmission lines clearly feeds into the on-going development of hydropower projects in Laos, as without these dams, there would be no need for the transmission lines, and without the transmission lines, the feasibility of these hydropower projects would be questionable. Until recently, the World Bank was also supporting projects in the GMS program, including support for a 230 kV transmission line from southern Laos to Cambodia. However, this project has since been cancelled.

In addition to hydropower development in Cambodia's northeast, there are also a number of large mining concessions, and numerous economic land concessions (land granted for large scale agriculture) in the 3S area. Not only is there a lack of information and understanding of the likely long-term cumulative impacts of hydropower in the 3S area, but it is also unclear how these other industrial developments will factor in. If large scale mining does start up in the region, and when the many ELCs in the area reach full scale production, water resources will be stretched further, and pollution is likely to be a major concern. No doubt increased access to power in the area will stimulate increased investment. Although this may boost the local economy, if on-going trends are anything to go by, it will also lead to an increase in land conflicts as more concessions are granted and more development projects become operational. If one key recommendation should come from this report, it is that more information needs to be gathered as to the full impacts of hydropower development in the area, and this information must be made publicly accessible. All actors, including affected communities, local and national authorities and decision makers, developers, financiers and civil society, must gain a deeper understanding of the benefits and dangers of the current development model, and take appropriate action, before it is too late.

1 Sam Chamroeun, Dept. of Environmental Planning and Legal Affairs, Ministry of Environment, Cambodia Water Resource Development: A review of the existing policy and legislative framework, 2007 (p10).