A HYDROPOWER dam slated for construction on the Sesan River in Stung Treng province could trigger "highly significant" social and environmental impacts if measures are not taken to mitigate its effects, according to an environmental impact assessment of the project.

The 179-page report warns that the US$816 million Lower Sesan II dam, scheduled to begin construction next year, could affect thousands of villagers living along the river.

"The project will cause some significant environmental and social impacts which must be balanced against the economic benefits of the project," the report states.

According to the study, conducted by Key Consultants Cambodia and Vietnam's Power Engineering Consulting Joint-Stock Company 1, the 480-megawatt dam will force the relocation of 4,785 people and lead to the destruction of 30,000 hectares of forest.

It is also likely to trigger changes in hydrology and water quality, and cut off access to migratory fish for thousands more people living along the Sesan.

Cosmetic consultations

Environmentalists have raised questions about the report, claiming residents still have not received sufficient information about the project.

"The company did not consult with communities upstream and downstream [from the dam], especially in Ratanakkiri," said Meach Mean, provincial coordinator for the 3S Rivers Protection Network.

Affected residents said they were not consulted about the report and continued to express concerns about the Lower Sesan II project.

"We do not want it to be built because we are concerned about losing our land for living, farming and planting rice," said Beang Teang, who represents 337 families in Sesan district's Sre Kor village.

Huon Kalib, a representative for four districts in Ratanakkiri, expressed concerns that the new dam would create problems similar to those produced by the 720-megawatt Yali Falls dam on the river in Vietnam.

"We are very concerned to be caught between the Yali [Falls] and Sesan dams," he said, adding that past water surges had swept away rice paddies, cattle and several villagers.

Carl Middleton, Mekong programme coordinator of International Rivers, a US-based advocacy group, said the high-risk nature of dam projects necessitated a close working relationship with local communities.

"This public acceptance can only be built through meaningful public participation in a decision-making process that explores a selection of options - including the "no-project" option," he said by email.

Prach Sun, a secretary of state at the Ministry of Environment, said the EIA had yet to be approved, and that inter-ministerial investigations were under way, including meetings with local residents.

"[We] are still checking the impacts on national fish resources, the environment, flooding and other impacts," he said, but did not say when a final decision would be made.