While described by proponents as a merely “tributary” dam, the construction of the Lower Sesan 2 (LS2) dam in Stung Treng province is causing immense fears of livelihood and ecosystem destruction . Located at the Sesan and Srepok River, just 25km before they join the Mekong River, the L2S, with a planned capacity of 400MW and a reservoir size of around 34,000ha, is in fact among the largest dam projects in Cambodia .
First feasibility studies were conducted in 1999 but the proposal was rejected as being financially unattractive, carrying large social and environmental costs . However, new Vietnamese and Chinese investors expressed their interest and a Memorandum of Understanding was signed on June 15, 2006 to go ahead with Environmental Impact Assessments (EIA) and planning of the 977$ million dollar investment . Although the EIA did not meet international standards, the LS2 was approved for construction in 2012 . Forest clearing started in 2013 and construction work in 2014, accompanied by a growing number of access ways and illegal logging outside the concession area . The dam is planned to be operative in 2017 .
Impacts on people and the environment will be devastating, but no proper consultation of affected people was held prior to the construction [1;3]. Upstream the dam, around 5000 people from 7 villages, comprised by Prov, Phnong and Lao ethnic minorities , will need to be relocated to make place for the reservoir  and an estimated 78,000 people will lose access to important migratory fish stocks . Resettlement land for the dispossessed was reported to overlap with protected areas and concessions land of other companies . Downstream, at least 22,000 people will be negatively affected by bad water quality and changing hydrology  and fish stock is expected to drop by almost 10% basinwide, while around 50 species will be endangered . Socio-ecological impacts in fact are expected to affect upstream Laos and downstream Vietnam, turning it into a transboundary issue . In summary, the dam will cause immense destruction of livelihoods, deforestation, habitat loss and large-scale ecological change .
Since years, the affected communities voice their preoccupations. They started protests marches, submitted formal concerns, and called on the spirits to stop the project . Compensations, generally inappropriate, were refused . Due to the transboundary nature of the project, international donors (Australia, Japan, Finland and USA) urged Cambodia to submit the project for prior consultation to the Mekong River Commission, which however has not been done . Some NGOs submitted formal complaints regarding concerns of human rights abuse ; while others request a new EIA . However, it seems that the interests of investors and urban elites are above those of affected communities.
Currently, it looks like that the project will go on, in spite of its devastating impacts.