The Don Sahong dam and the Mekong dolphin



Posted on 19 February 2014  | 
The Don Sahong dam and the Mekong dolphin - briedfing cover
© WWF-CambodiaEnlarge
The Mekong River is home to a Critically Endangered, declining population of 85 Irrawaddy dolphins. An isolated dolphin group on the border of Lao People’s Democratic Republic (Lao PDR) and Cambodia are the only dolphins left in Lao PDR. Plans to construct the Don Sahong hydropower dam in a channel immediately upstream from these dolphins is a major threat to both that group and the whole Mekong population.

Hydropower dams create electricity and can support some development aspirations of the government and people of Lao PDR, however they also pose a significant threat to biodiversity. Freshwater dolphins require hydrologically complex habitat that can be degraded by infrastructure, and dolphins are very sensitive to disturbances such as construction.

This Science Brief examines the potential impacts that the Don Sahong dam may have on dolphins, highlighting areas where knowledge gaps or risks are unrecognized by the proponent’s impact assessments. The risks posed by a variety of threats are examined using an internationally standard process for risk assessment.

Major risks to the local dolphin population are through excavation and boat traffic at the site, which are expected to precipitate the loss of dolphins from Lao PDR. The scale of the threat to the whole population is magnified through ecosystem degradation, expected decline in fisheries, as well as the cumulative effects of disturbance and stressors on the dolphins.

The Don Sahong Dam poses a high risk to the Mekong’s dolphins. Its effects probably cannot be mitigated, and certainly not given the limited and vague plans outlined in the environmental impact assessment, which address a smallfraction of the risks identified here.

Alternatives to Don Sahong exist, such as the Thako Project, which the proponents of Don Sahong agree has much lower risk to biodiversity while still producing significant electricity. Despite the repeated mantra of “no significant impact” on dolphins, the project proponents state that “construction impacts [are] necessary”. Not building a dam at Don Sahong is not an irreparable blow to the development aspirations of Lao PDR or its ability to produce electricity, but building it would almost certainly cause the extirpation of Irrawaddy dolphins from Lao PDR and it could very well precipitate the extinction of species from the Mekong River.

There is no doubt that conservation of the Mekong’s last dolphins will be difficult, but the attitude implicit in the proponent’s impact assessments –that the dolphin population is already vulnerable and therefore should not stand in the way of development– will achieve nothing but to seal their fate.
The Don Sahong dam and the Mekong dolphin - briedfing cover
© WWF-Cambodia Enlarge

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