Daechung Dam, a major drinking water source in the Chungcheong area, has seen a rise in algal blooms, with warnings issued at key points for three consecutive years. The climate crisis has led to increased rainfall, creating conditions conducive to the inflow of turbidity and nutrients, while rising water temperatures have exacerbated the algal growth.
The watershed of Daechung Lake has a large area that can contribute to the inflow of phosphorus, a key substance causing algal blooms. It is the second-largest multipurpose dam in terms of surface area after Chungju Dam, and its geography, with areas prone to algal accumulation, makes it particularly vulnerable to blooms.
To manage the algal blooms in Daechung Lake, the government plans to reduce incoming phosphorus and quickly remove existing blooms. Since algal growth is influenced by water temperature, sunlight, retention time, and nutrient inflow, effective management requires both watershed management and internal lake responses.
Initially, the government will strengthen the management of household wastewater outside sewage treatment areas. It will expand public sewage treatment facilities and install community wastewater storage systems to collectively treat wastewater. Inspections and guidance for individual wastewater treatment facilities, such as septic tanks, will also be enhanced, and public management of septic tanks will be promoted in collaboration with local governments.
Management of livestock manure and compost will also be intensified. Excessive application of manure and liquid fertilizer beyond recommended levels will be converted into energy, reducing discharge sources and greenhouse gas emissions. Nutrient management in agricultural land will be implemented in three stages: reduction of inputs, reduction of outflows, and on-site treatment. Fertilizer usage will be minimized based on nutrient levels in the soil, and optimal management techniques, such as water control devices, will be promoted to reduce nutrient runoff.
On-site responses to stagnant water areas will be strengthened. The ministry will focus on managing areas near intake points, such as Chudong and Munui, as well as algal bloom sites like Hoenam, Daejeongri, and Chusori. Remote-controlled underwater vehicles will be used to selectively remove sediment layers containing high concentrations of nutrients and algal seeds, and the effectiveness of these actions will be analyzed.
Early removal of algal blooms will also be pursued. Algal removal boats will operate near intake points, and low-temperature plasma facilities will be upgraded. The low-temperature plasma facility in Daejeongri is currently being relocated to the Chusori area, where algal blooms are occurring, and a new pressurized removal device will be installed in the Hoain Stream for demonstration starting this year.
The water management system will also be improved. The ministry plans to establish AI-based digital twin technology to replicate watershed characteristics in a virtual space and predict algal blooms. During flood periods, a pilot project will be launched to optimize the operation of Daechung Dam, considering turbidity inflow and available water capacity to quickly eliminate turbidity and nutrients.
Through these measures, the ministry aims to reduce total phosphorus emissions in the Daechung Lake watershed by more than 30% by 2030 and to lower summer algal blooms by up to 50%. Kim Eun-kyung, the ministry's water environment policy director, stated, "We will do our best to ensure the safety of drinking water for 3.7 million residents in the Chungcheong region by harmonizing the fundamental principle of managing discharge sources with proactive on-site responses."
* This article has been translated by AI.
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