The following Frequently Asked Questions (FAQs) summarise key findings on the MRC commissioned Strategic Environmental Assessment  (SEA) of proposed hydropower on the Mekong mainstream, Final Report. The intention of these FAQs is to summarise the SEA into brief points, and to address some of the questions which go beyond the report.

Main questions answered in the FAQ include:

  1. What is SEA?
  2. What are some key messages in the SEA Final Report outcomes?
  3. What are some of the Final Report’s main conclusions?
  4. What are MRC’s perspectives on the SEA?
  5. What are some of the next steps for the MRC on SEA?
  6. What are some of the stakeholders’ perspectives on the SEA?
  7. How does the SEA relate to the BDP?
  8. How does the SEA relate to the Procedures for Notification, Prior Consultation and Agreement (PNPCA) Process?

What is the SEA?

An SEA addresses the broader strategic issues that go beyond a single project: An SEA follows a similar approach to project-specific Environmental Impact Assessments (EIAs), but considers larger boundaries in terms of time, space and subject coverage. SEA is used as a tool to examine broader strategic issues to be resolved and decided upon at the administrative level prior to making project-specific decisions. The SEA, commissioned by the MRC, provides an understanding of the implications of proposed mainstream hydropower development along the Mekong River, and presents recommendations on whether and how these projects should best be considered by the Member Countries.

SEA is a comprehensive approach to assist Member Countries and wider stakeholders assess development risks and opportunities of mainstream Mekong Hydropower projects: The SEA was a collaborative process involving the MRC Secretariat, government agencies of the four Member Countries as well as civil society, the private sector, other stakeholders. The SEA process was authorized by the MRC Joint Committee as part of the overall Initiative on Sustainable Hydropower (ISH) a cross-cutting initiative working together with all MRC programmes. The stakeholder participation process for the SEA was funded and coordinated through the ISH. The SEA comprised 4 main phases: (i) scoping, (ii) baseline assessment, (iii) opportunities & risks assessment, and (iv) avoidance, enhancement and mitigation assessment. Each phase included the preparation and circulation of a set of reports as basis for consultation and feedback.

SEA is a result of growing response to growing interest in hydropower development along the mainstream Mekong: The movement towards the development of hydropower resources along the mainstream Mekong is a result of multiple factors: i) strategic priorities of Lao PDR and Cambodia to generate revenues from power exports; (ii) the need for Thailand and Vietnam to meet their increasing energy needs; as well as (iii) the increased global push to reduce green house gas emissions from electricity generation. Completion of large hydropower projects in the Upper Mekong River in China, and their potential to increase dry season flows downstream, demonstrated the possibility of river flow regulation through hydropower development in the Lower Mekong Basin (LMB) as well. Many proposed projects have been identified over the last 15 years, however, it is the recent revival of interest by private sector developers, mostly from the Asian region, that has moved these plans forwards to a more advance stage of feasibility study, backed by national governments.  The SEA was launched as a response to a high volume of investor and developer interest in the implications of twelve hydropower projects proposed for the lower mainstream Mekong River. It is intended as a preparation measure for, and as input to, the MRC's formal consultation process under the PNPCA, to feed into the MRC Basin Development Plan (BDP), and ultimately to inform national decision processes concerning the mainstream proposals.

The SEA draws extensively from MRC Programme work: An inclusive and participatory process, the SEA builds upon the work of MRC programmes over several years, especially work on scenario assessments by the Basin Development Plan (BDP-Phase 2), the modelling team in the Information and Knowledge Management Programme (IKMP), and the data and studies of the Environment, Fisheries and Navigation Programmes. The SEA featured extensive consultations with government agencies, civil society, private sector developers and donor partners both at the national levels in each of the four LMB countries. Regionally, China participated in the SEA process through the Ecosystem Study Commission for International Rivers (ESCIR), by exchanging information through its modelling teams, facilitating visits to the dams in China and contributing presentations to SEA regional workshops.

The SEA assesses alternative mainstream Mekong hydropower development strategies to identify regional distribution of risks and opportunities: The SEA evaluates regional cost distributions and benefits with respect to economic development, social equity and environmental protection. As such, the SEA supports the wider Basin Development Planning (BDP) process by complementing the assessment of basin-wide development scenarios with more in-depth analysis of power-related and cross-sector development opportunities and risks of the proposed mainstream projects in the Lower Mekong Basin.

The SEA considered four strategic options for mainstream hydropower development:

  1. No mainstream dams;
  2. Deferred decision on all mainstream dams for a set period;
  3. Gradual development of mainstream power; and
  4. Market driven development of the proposed mainstream projects.

The SEA assessed each of the four options during four assessment phases. Based on findings of these assessments, the SEA presented detailed recommendations to LMB governments on each strategic option as guidance on critical issues, whichever strategy is adopted.

The SEA offers conclusions and recommendations that places 12 LMB mainstream projects in the context of sustainable development of the Mekong River and the implementation of the 1995 Mekong Agreement: The SEA directly enhances baseline information and the assessment framework for subsequent government reviews of project-specific EIAs for the mainstream dams to be prepared by developers. It helps the MRC identify studies, investigations and research needs to be undertaken by MRC Programmes to reduce risks and uncertainties associated with mainstream dam development.

What are some key messages in the SEA Final Report outcomes? 

The SEA presents opportunities and risks associated with mainstream hydropower development: The 12 proposed LMB mainstream projects involve considerable development risks as well as opportunities for the LMB countries. Significant risks include an irreversible loss in Mekong fisheries along with related livelihoods and food security impacts, changes in sediment flows, sediment-nutrient balances and ecological diversity, and the displacement of communities within and surrounding the dam sites. Opportunities include power security and electrification of the national grids, revenues from power exports, increased foreign investment and trade, positive economic spinoffs from the large investments in goods and services, greater navigability of the river with higher water levels, expansion of irrigation agriculture, and offsetting of greenhouse gas emissions from thermal power plants.

Summary of economic opportunities & risks for LMB countries from 12 LMB mainstream projects


  • Significant benefits from power sector development
  • Secured and less expensive power for industry
  • Economic diversification in the long term
  • Serious adverse consequences for fisheries and fishers, food security and poverty reduction
  • Fishery losses are likely to outweigh benefits of power production in the short to medium term
Opportunities Risks
  • Less expensive and secure national power supply (replacing costly diesel imports)
  • Increased competitiveness in the manufacturing sector
  • Increased government revenue from power exports and taxes
  • Longer term strategic flexibility in power supply once the concession period ends
  • Increase in irrigable area and agricultural productivity in some areas
  • Loss of fishery resources and significant impact on food security
  • Livelihoods disruption of over 1.6 million fishers
  • GDP losses due to economic losses in fisheries and agriculture
  • Ancillary services and processing would suffer
  • Reduction in sediment and nutrient transport to the Tonle Sap system, and associated impacts on primary production, flood forests and local/migratory fish
  • Loss of river bank gardens - likely to be significant for riparian communities in some areas
  • Decline of agricultural productivity in flood plains
  • Loss of tourism assets and revenue
  • Lack of a national grid may inhibit equitable distribution of power
  • Loss of biodiver


  • Significant overall economic benefit, likely to be unevenly distributed
  • Significant negative impacts on vulnerable communities
  • Net revenues to the Government of Lao PDR may help alleviate negative impacts
Opportunities Risks
  • Significant economic stimulus of foreign direct investment in LMB mainstream hydropower
  • May receive net revenues during the concession period depending on the design of financing agreement and adequate oversight capacity
  • Likely to see significant benefits after 25 year concession period ends and the projects are transferred to the Government of Lao PDR.
  • Longer term strategic flexibility in power supply once the concession periods end
  • Increase in irrigable area and agricultural productivity in some areas
  • Improved navigability for medium and large vessels upstream of Vientiane
  • Possibility of macro-economic imbalances developing due to a booming hydropower sector
  • Loss of fisheries, and associated impacts on food security and livelihoods of vulnerable populations
  • Loss of river bank gardens, to be particularly significant in Lao PDR
  • Loss of valuable tourism assets
  • Loss of biodiversity


  • Overall economic benefit although insignificant for national economy
  • Economic risks to livelihoods of riparian communities in the basin
  • Likely overall economic lossLosses borne predominantly by poorer communities in the Mekong delta
Opportunities Risks
  • Will receive a large portion of the economic benefits from power imports
  • Improvement in river navigability for medium and large vessels in upper reaches of the LMB
  • Loss of fisheries
  • Loss of agricultural land
  • Possible loss of eco-tourism assets

Viet Nam

  • Likely overall economic loss
  • Losses borne predominantly by poorer communities in the Mekong delta
Opportunities Risks
  • Increased economic benefits of improved power supply (from imported power)
  • Significant loss in fresh water and marine capture fisheries and aquaculture
  • Adverse impacts on affect livelihoods of fisher folk in the Mekong Delta - especially lower income groups
  • Loss of sediments and associated nutrients, and significant adverse affects on deltaic sedimentation, fisheries and agriculture.

What are some of the report’s main conclusions? 

The SEA Consultant Team recommends a 10-year deferral on mainstream hydropower development: Due to the uncertainties regarding scale and reversibility of impacts in such a complex river system, the SEA Consultant Team advised that decisions on mainstream dams should be deferred for a period up to ten years. Reviews are recommended every three years to ensure that necessary knowledge to strengthen the understanding of natural systems are developed, and management and regulatory processes are conducted effectively.

Cumulative and trans-boundary impacts are of high importance: The impacts of the LMB mainstream projects must be assessed in relation to the cumulative and trans-boundary impacts of a growing number of LMB tributary hydropower projects and large storage dams on the Lancang River in China. There exists plans and proposals to build 41 large hydropower schemes on the Mekong River tributaries by 2015; 8 storage schemes in the Lancang-Mekong Basinin China; as well as other non-dam investments within the Mekong’s natural resource systems. Reviewing the potential impacts of individual power projects in isolation does not present a complete picture of the overall impacts. Environmental and social impacts of all major proposed investments in the Mekong River Basin should be evaluated to determine the cumulative regional impact. The SEA presents cumulative and transboundary impacts

The SEA presents transboundary impacts of the proposed hydropower schemes, developed through extensive consultation with stakeholders in MRC Member Countries. It presents opportunities and risks associated with the proposed projects, while calling for the assurance of equitable development benefits at national and local levels.

Equity of development benefits at the national and local levels need to be assured: One central issue addressed in the SEA Final Report is the potential distribution of costs and benefits, both locally and regionally. Revenue from electricity generation at the national level need to be shared with affected and vulnerable riverine communities, and be rightfully allocated towards education, healthcare, social improvement and economic development. Benefits accrued at the regional level need to also need to be shared with vulnerable groups who may suffer the greatest losses in livelihood streams, food security and cultural practices. It is important to recognise that impacts of hydropower projects are trans-boundary in nature.

As a technical advisory body, to what extent does the MRC Secretariat support the final SEA recommendations? 

As with any commissioned study, the SEA Report is not an official MRC-approved document.

The MRC pro-actively supports Member Countries in making decisions regarding mainstream hydropower proposals with the aim of reaching a common regional agreement: One of the main objectives of the SEA is to identify knowledge gaps on key issues that affect the entire LMB and to enable informed judgments in arriving at its decisions. In the event that after the joint consultation process Member Countries decide to pursue mainstream development, the MRC will support Member Countries by providing necessary guidance on planning and design issues relating to project sustainability and mitigation of impacts as well as monitoring requirements.

Mainstream hydropower development is complex, irreversible and controversial: Regional consensus must be reached for a long-term vision of the balance between water resource development and protection. These decisions, coupled with power sector strategies, national policies, bilateral and regional agreements in the power sector, as well as other impacted sectors (fisheries, agriculture and navigation) need to internalize environmental and social implications of mainstream hydropower development to achieve national development and poverty alleviation targets.

What are some of the next steps for the MRC on the SEA? 

The MRC has made the SEA Final Report available for public viewing on its website. In addition, the MRC has translated the Summary of the Final Report to all riparian languages, also available on the MRC website.

The MRC has proposed consultations with the MRC Programmes, and possibly with Member Countries, on the final SEA report findings and recommendations for next steps.

SEA recommendations assist the MRC with future Programme planning: Recommendations for actions proposed in the SEA such as, research, data collection, monitoring, consultation processes, and strengthened management and regulatory systems can assist the development of MRC Programme work plans for the upcoming years in cooperation with MRC development partners and stakeholders.

What are some of the stakeholders’ perspectives on the SEA? 

The SEA involved extensive consultations: Preparation of the SEA involved the participation of over 60 line agencies, 40 NGOs and civil society organisations and some 20 international development organisations in meetings and workshops. China also participated in the process through the Ecosystem Study Commission for International Rivers (ESCIR).

Stakeholder views on development in the Lower Mekong Basin is highly variable, as observed during the SEA process: Stakeholders’ views on avoiding, deferring and proceeding with mainstream hydropower development formed the basis for the four Strategic Options presented in the SEA Report.

Stakeholder consensus on SEA topics include strengthening communications with affected communities and equitable benefit sharing: Stakeholders agreed that trans-boundary impacts need to be addressed extensively by national governments, including those that will be caused by projects already underway. Vulnerable communities need to be educated about the full extent of how they will be impacted by the projects. Communication strategies and mediums of information exchange among riverine communities need to be significantly improved to facilitate communication. Stakeholders also agreed that meaningful steps need to be taken to assure equitable distribution of benefits and costs of mainstream Mekong hydropower development. Mechanisms should be developed to deliver fair and equitable compensation and benefits to affected communities at national levels.

The SEA is time bounded and provides strategic inputs to the ongoing BDP: SEAs are also part of the legal framework of assessments required by an increasing number of LMB countries. The SEA of proposed mainstream hydropower projects focuses on a subset of the scope of the broader BDP and specifically addresses the risks and opportunities of one group of highly contested projects. The Basin Development Plan is an integral part of the 1995 Mekong Agreement as a rolling joint planning process to help the MRC member countries develop and manage the Mekong water and resources in a sustainable and equitable manner. The BDP works across all water related sectors (irrigation, navigation, fisheries, flood management, environment protection, etc), analysing potential synergies and conflicts between them, to provide a basin-wide perspective on how well national water resources development plans, including hydropower development, will help achieve an acceptable balance between economic, environment and social outcomes in the LMB.

The SEA and the BDP have different scopes: The SEA focuses on mainstream hydropower dams, regional power, and other energy-related issues within the current planning cycle in order to address urgent concerns in the basin. The scope of BDP goes beyond the consideration of mainstream dams to look at a broad range of future development scenarios, including water for irrigated agriculture and urban/ industrial use, tributary hydropower, and flood risk management in the Mekong Delta. The SEA complements the BDP scenario assessment with recommendations for avoidance, mitigation and enhancement measures. It also helps Member Countries broaden their planning options by providing alternative assessments for energy and power. Both the SEA and the IWRM-based Basin Development Strategy provide the framework of analysis to conduct the MRC's prior consultation process on any individual project.

The SEA provides recommendations to address impacts of the BDP Definite Future Scenario (DFS): The SEA provides recommendations that address potential impacts of the BDP Definite Future Scenario (DFS), including operational considerations for the Lancang-Mekong mainstream dams in China and up to 28 tributary hydropower projects in the Lower Mekong Basin. In preparing the IWRM-based Basin Development Strategy that draws on both BDP scenarios and SEA assessments, Member Countries have agreed to prioritize the development of mitigation measures for the DFS in the next five years. This will be part of the early implementation of the Strategy upon its approval.

The Process of incorporating the SEA outcomes into the BDP is ongoing: The IWRM based Basin Development Strategy is being updated in preparation for approval by the MRC Council in December 2010. How the SEA can specifically be incorporated into the BDP was one important discussion point at the recent Third BDP Regional Stakeholder Forum and is being addressed by the MRC Secretariat. The Strategy draws on the results of both the BDP Scenarios and the SEA to build Member Countries’ shared understanding of the opportunities and risks associated with water resources development, including hydropower development in the LMB. This will lead to agreement on a set of priority Strategic Guidance that Member Countries will implement to optimize opportunities and minimize the risks. Both processes have recommended similar further studies to address uncertainties, and they have been included as priority actions for the next five years by the Member Countries and the MRC. For proposed mainstream dams, recommendations include the implementation of the MRC’s PNPCA process and national environmental licensing processes. The SEA will be used to generate detailed discussions on the hydropower projects during these review processes, while the BDP provides a broader picture of cumulative impacts of hydropower and water resource developments.

How does the SEA relate to the basin Procedures for Notification, Prior Consultation and Agreement (PNPCA) Process? 

MRC Member Countries adhere to the PNPCA process to ensure regional cooperation: At the regional level, MRC Member Countries have adopted a protocol under the 1995 Mekong Agreement to submit mainstream project proposals to other Member Countries before any decision is made to proceed. This process requires extensive prior consultations aimed to reach agreements on whether to proceed with a project and if so, under what conditions. The full PNPCA process was first triggered by the Government of Lao PDR for the Xayaburi Hydropower Proposal in September 2010.

The SEA is immediately relevant to the MRC's PNPCA process: The SEA provides the overall framework for analysis of risks and opportunities of mainstream hydropower development, within which individual projects such as the Xayaburi Dam will be assessed. It examines cumulative impacts, as well as questions of distribution of impacts and benefits.

The SEA relates to the PNPCA process as a technical input: The MRC has been working pro-actively to assist Member Countries prepare for decisions on mainstream hydropower proposals. Much of the MRC's consultative research on fisheries and other environmental issues over the past years has been considered and synthesized in the SEA. The SEA process itself included a national and regional dialogue process where all parties were exposed to multi-stakeholder consultative approaches, and familiarized with important regional issues. This enables the PNPCA process to start at a more advanced level of understanding and cooperation. In compliance with the 1995 Mekong Agreement, the PNPCA states that in the event of the development of mainstream hydropower projects, rigorous prior consultation that aims at arriving at an agreement by the Joint Committee of the MRC is required. This will be a negotiation process guided by the knowledge base accumulated by the MRC and others parties, which has been summarised in the SEA.