The Don Sahong Hydropower Project (DSHP) is a run-of-river hydropower scheme located in the Khong District of Champasak Province in Southern Lao PDR. The original scheme with a generation capacity of 260-MW was completed before the end of 2019 and another 65-MW was completed in June 2024 to increase the total capacity to 325-MW.
The Don Sahong powerhouse is located on the southern end of the Sahong channel, one of seven major channels of the Mekong River in the Siphandone (Four Thousand Islands) area that flow over the geological feature called the “Great Fault Line”. The project utilises about 15-25% of the total annual Mekong flow, depending upon the variation in river flows from year-to-year.
The powerhouse and associated embankments create a dam on Sahong Channel between the islands of Don Sahong and Don Sadam, thereby inundating up to approximately 2.8 km² of land and creating a headpond or small reservoir. The project utilises a natural fall of approximately 20 m across the Great Fault Line for power generation.
The project efficiently produces safe and reliable renewable energy, and also provides social infrastructure, employment and educational opportunities to support local development. Accordingly, a strong focus has been placed on understanding the social and environmental impacts of the project. Social and environmental management plans are being implemented through local consultation and coordination to extend the opportunities for local people to improve their livelihoods, a key criterion for the success of the project.
In March 2006 an agreement was signed with the Government of Lao PDR (GOL) to conduct Initial Feasibility Study and Environmental Impact Assessment for the Don Sahong Hydropower Project. These studies were completed in December 2007 and a Project Development Agreement with the GOL was signed in February 2008 for preparation and delivery of technical, environmental and social, financing, and contractual documents for project implementation to international industry standards. Since 2007, the range of technical, social and environmental studies and documentation has been expanded significantly. Several upgrades and extensions of the scope of the feasibility and social and environmental reports brought the project to a point where the reference design and environmental and social monitoring and management plans (ESMMP) could be developed.
The Don Sahong Hydropower Project (DSHP) is one of 11 Mekong mainstream projects proposed since the 1990s by the four lower Mekong Basin countries. These projects are subject to the international Procedures for Notification, Prior Consultation and Agreement (PNPCA) by the Mekong River Commission (MRC). Don Sahong is the smallest of the eleven mainstream dam projects, with relatively minor impacts for a relatively large production of electricity. The most significant environmental impact of the project is generally considered to be the potential obstruction of fish migration, which has been a focus of DSPC’s environmental studies and management.
The Don Sahong project is situated on one of seven main anabranch channels of the Mekong River at Khone Falls. The project will utilize only about 15-25% of the total Mekong flow, with about 75-85% of the flow continuing down the other six natural channels. Therefore, there is very little alteration of natural flow patterns or sediment transport across Khone Falls. Improvements to the other six channels and removal of physical barriers to fish migration provides safe routes for fish passage. The Don Sahong Project is therefore fundamentally different from all existing or proposed Mekong mainstream projects, which are all based on much larger cross-river dams which block the entire Mekong flow.
Despite this difference, the Mekong River Commission’s (MRC) Preliminary Design Guidance for Proposed Mainstream Dams in the Lower Mekong Basin (MRC, 2009) has been an integral part of the project’s design and proposed measures to avoid, minimize or mitigate environmental and social impacts. The key principles of the MRC design guidance have been central in the design of the project, and its associated environmental and social management plans. The MRC design guidance addresses the following:
