With roughly one year of monitoring data, the MRC says it’s still very early in the process to draw any conclusions. A multinational team of investigators for the MRC-Joint Environmental Monitoring (JEM) is testing protocols that measure five key indicators of the river’s health, namely hydrology, sediment, water quality, aquatic ecology, and fisheries. By testing this at two relatively new hydropower projects – the Don Sahong and Xayaboury – the MRC aims to create monitoring methods and standards that all hydropower operators on the Mekong mainstream will follow in the future. Among its most significant findings, the monitoring teams observed that the overall river flow patterns did not change much. The MRC stated that the river’s ecological health was “good” at upstream dam sites, “moderate” within the dam impoundment sites, and “moderate” downstream of both dams. Water quality remains “within human health thresholds”.
Once water passes through the dams, “there is little evidence of change in downstream water quality.” The monitors also detected some daily water level fluctuation downstream of the Xayaboury project in Laos – which could affect the ecosystem. However, this didn’t occur downstream of the Don Sahong dam.
Finally, the team observed some changes in fish diversity upstream of Xayaboury, with some stability from 2017 to 2019 and a reduction in 2020. Downstream of the reservoir, diversity remains high. On the other hand, fish catch seems stable, with a high value reported in 2017, lower in 2018-2019 and higher again in 2020.
Overall, this Joint Environmental Monitoring report is part of a broader effort by the MRC – which represents Cambodia, Laos, Thailand and Vietnam – to strike a balance between the economic and societal benefits of hydropower. Read more at: https://www.nationthailand.com/international/ann/40019244
