The Lancang-Mekong River, which runs through China, Myanmar, Laos, Thailand, Cambodia, and Vietnam, is among rivers with the richest biodiversity and water and ecological resources in the world. Its health is vital to the livelihood of residents along the river, and moreover, affects the life of the people of Southeast Asia and beyond.

However, increasing environmental problems stand out in the process of rapid industrialization and urbanization of Mekong countries, such as water pollution and obvious environmental deterioration caused by industrial, agricultural and domestic discharge. Hence, the systematic assessment of Lancang-Mekong freshwater ecosystems is necessary to understand the health status of river basin and facilitate timely adjustment to regional development policies.

The China-ASEAN Environmental Cooperation Center (CAEC)/Lancang-Mekong Environmental Cooperation Center (LMEC) and the Conservation International (CI) have carried out demonstration projects under the framework of Lancang-Mekong environmental cooperation. In collaboration with Beijing Normal University (BNU) and Yunnan Institute of Environmental Science (YIES), they applied the Freshwater Health Index (FHI) to the first health assessment of mainstream Lancang in Xishuangbanna Prefecture and Erhai Lake in Dali City, Yunnan Province, China. Meanwhile, they worked with Hainan Institute of Environmental Science (HIES) on a comparative study of freshwater ecosystem management in the demonstration project of Songtao Reservoir in the upper Nandu River in Hainan Province.

FHI makes up for the current freshwater ecosystem assessment indicators by highlighting healthy freshwater ecosystems and provided services, as well as relationships between governance and stakeholders involved in freshwater management and use. There are three components under the FHI framework: ecosystem vitality, ecosystem services, and governance & stakeholders. In specific, ecosystem vitality covers water quantity, water quality, basin condition, and biodiversity. Ecosystem services contain provisioning, regulation & support, and cultural services. Governance & stakeholders include policy environment, stakeholder engagement, vision & adaptive governance1 , and effectiveness. These indicators each consist of several sub-indicators.

The research teams carried out many field surveys and stakeholder workshops in Xishuangbanna, Dali, and Songtao Reservoir. They obtained data related to ecosystem vitality and ecosystem services from literature and yearbooks, environmental monitoring datasets, remote sensing images, field visits, questionnaire surveys, and (SWAT) model simulations, and collected data related to governance & stakeholders through stakeholder questionnaire.

The FHI indicators were weighted using the Analytic Hierarchy Process (AHP) based on values assigned by experts and representatives from the Ministry of Ecology and Environment (MEE), agencies directly under the Ministry of Water Resources (MWR), agencies directly under Yunnan Provincial Department of Ecology and Environment, Hainan Provincial Department of Ecology and Environment, local government departments, research institutions, non-governmental organizations (NGOs), and businesses. On this basis, the specific and overall scores for the mainstream Lancang, Erhai Lake, and Songtao Reservoir were calculated.

The FHI-based studies show that the freshwater ecosystems of mainstream Lancang, Erhai Lake, and Songtao Reservoir are in good health overall. In the next few years, followup assessments of these river basins will be conducted, and based on score changes, policy recommendations will be offered for local freshwater ecosystem management.