As an indicator of ecosystem restoration, the water quality of the Han River in Seoul has shown improvement for three consecutive years, according to the 2024 survey by the Seoul Health and Environment Research Institute.
Particularly, the increase in dissolved oxygen (DO), which indicates the health of the aquatic ecosystem, and the decrease in total nitrogen (TN) and total phosphorus (TP) concentrations, which are major indicators of water pollution, suggest that the Han River’s water quality is approaching a pristine state.
Under the river’s living environment standards set by the Framework Act on Environmental Policy, the 2024 water quality grades for the Han River were analyzed as “Excellent” for dissolved oxygen (DO), “Good” for total organic carbon (TOC), and “Slightly Good” for total phosphorus (TP). The river’s annual average dissolved oxygen concentration reached 10.4 mg/L, falling within the highest water quality grade (DO 7.5 mg/L or higher).
Conversely, the reduction in the concentrations of total nitrogen (TN) and total phosphorus (TP), which indicate water pollution, is a result of decreased inflow of pollutants. Despite the recent decade seeing the highest average temperatures and a consecutive three-year rise in water temperatures in Seoul, improvements in sewage treatment facilities and real-time water quality management policies have enhanced the Han River’s water quality.
The Seoul city government has actively expanded total phosphorus treatment facilities at water recycling centers and restructured tributary rivers flowing into the Han to improve discharge water quality. In addition, the Seoul Health and Environment Research Institute has established a real-time monitoring system that oversees 16 water quality parameters, including dissolved oxygen, 24 hours a day through automatic water quality measurement stations, providing Han River water quality information to the public via the ‘Open Data Plaza.’
With the official operation of the upcoming ‘Han River Bus’ and the hosting of the ‘2nd Leisurely Han River Three-Item Festival,’ additional water quality tests are planned ahead. As part of the measures to ensure public safety and enjoyment, the city plans thorough pre- and post-event water quality management for the extensive event visited by approximately 630,000 people last year.
In March of last year, Seoul announced the ‘Great Han River’ project, focusing on restoring the naturalness of the Han River and rehabilitating the riverside ecosystem. This initiative, an upgraded version of the 2007 ‘Han River Renaissance’, includes plans to plant an additional 1.56 million trees in the Han River forest and refurbish the ecological park and natural river banks by 2026.
Park Joo-sung, director of the Seoul Health and Environment Research Institute, stated, “To maintain and further enhance the Han River’s water quality, systematic and scientific management is essential. We will utilize the real-time water quality measurement network to analyze water quality changes closely and identify pollution sources promptly for effective response.”