Presidential Letter on Don Sahong Dam and River Dolphins

Mr. Hans Guttman
Chief Executive Officer
Mekong River Commission Secretariat
Vientiane, Lao PDR

Minister H.E. Lim Kean Hor
Minister of Water Resources and Meteorology
Chairperson of Cambodia National Mekong Committee
Member of the MRC Council for Cambodia

Minister H.E. Noulinh Sinbandhit
Minister of the Ministry of Natural Resources and Environment
Chairperson of Lao National Mekong Committee
Member of the MRC Council for the Lao PDR
Vientiane, Lao PDR

Minister H.E. Vichet Kasemthongsri
Minister of Natural Resources and Environment
Chairperson of Thai National Mekong Committee
Member of the MRC Council for Thailand
Bangkok, Thailand

Minister H.E. Nguyen Minh Quang
Minister of Natural Resources and Environment
Chairperson of Viet Nam National Mekong Committee
Member of the MRC Council for Viet Nam
Hanoi, Viet Nam

Minister H.E. Dr. Ouk Rabun
Minister of Agriculture, Forestry and Fisheries
Phnom Penh, Cambodia

Minister H.E. Say Sam Al
Minister of Environment
Phnom Penh, Cambodia

Minister H.E. Suy Sem
Minister of Mines and Energy
Phnom Penh, Cambodia

Minister H.E. Thong Khon
Minister of Tourism
Phnom Penh, Cambodia

Secretary General H.E Te Navuth
Secretary General Cambodia National Mekong Committee
Phnom Penh, Cambodia

Ambassador Daniel A. Clune
U.S. Ambassador to Laos
Vientiane, Lao PDR.

Ambassador William E. Todd
U.S. Ambassador to the Kingdom of Cambodia
Phnom Penh,Cambodia

Ambassador David B. Shear
U.S. Ambassador to Vietnam
Hanoi, Vietnam

Ambassador Kristie A. Kenney
U.S. Ambassador to the Royal Kingdom of Thailand
Bangkok, Thailand

Ambassador Alison Burrows
Australian Ambassador to Cambodia
Phnom Penh,Cambodia

Prime Minister Samdech Akka Moha Sena Padei Techo Hun Sen
Prime Minister of the Royal Government of Cambodia
Phnom Penh, Cambodia

14 May, 2014

Dear Sirs and Madames,

The Society for Marine Mammalogy is the world’s largest professional group dedicated to the study of marine mammals, with a membership of approximately 2,000 scientists from 60 countries. Its goal is to facilitate the understanding and conservation of marine mammals and the ecosystems that support them.

The Society is very concerned about the future of river dolphins, including the critically endangered Mekong population of Irrawaddy dolphins. The recent extinction of the Yangtze dolphin (or baiji) illustrates the extreme vulnerability of river dolphins to the impacts of human activities.

Construction of any dam in the Mekong River’s mainstream would represent a great risk to the survival of these dolphins. A dam would exacerbate already existing problems associated with degraded water quality and negative changes in the hydrologic and geomorphic characteristics of the river. It would also interrupt the movements of migratory fish.

Most immediately, construction of the Don Sahong Dam would lead to the disappearance of dolphins in Lao PDR, because of their close proximity to the dam site, and have serious downstream impacts on the dolphins in Cambodia. In contrast, the alternative Thako Hydropower Project would not involve constructing a barrier across a mainstream channel of the Mekong River and thereby would appear to present less of a threat to the dolphins.

Along with a group of international dolphin experts, I recently attended a workshop in Phnom Penh concerning Mekong dolphins. The group agreed that, given the state of knowledge of the population of Irrawaddy dolphins in the Mekong River, range states should abide by the 10 year moratorium on the construction of mainstream dams in the Mekong River as recommended in the Strategic Environmental Assessment of Hydropower on the Mekong Mainstream prepared for the Mekong River Commission (

It is important to note that further hydropower development in the Mekong Basin is also bound to have detrimental impacts similar to those listed above for dolphins  on other threatened aquatic megafauna such as the Mekong giant catfish (Pangasianodon gigas), giant pangasius (Pangasius sanitwongsei), Siamese giant carp (Catlocarpio siamensis), giant river carp (Probarbus jullieni), Mekong freshwater stingray (Himantura chaophraya), and Siamese crocodile (Crocodylus siamensis).

Please do not hesitate to contact me if you would like further advice from Society members with appropriate technical expertise.



Helene Marsh