Environment ministry to open four Nakdong River weirs to curb algae

The environment ministry said it will sequentially open four weirs in the lower Nakdong River from July 30 to Aug. 5 to reduce spreading blue-green algae.

The phased release of Gangjeong Goryeong, Dalseong, Hapcheon Changnyeong and Changnyeong Haman weirs will lower water levels by 0.54 to 0.9 meters based on scenario analyses by the National Institute of Environmental Research. The action coincides with the seasonal algae management period running from May 15 to Oct. 15 and targets sections where blooms are most frequent.

To minimize impacts on fish, shellfish and the aquatic ecosystem, water levels will drop at a rate of 3 centimeters per hour. Officials plan to monitor the ecosystem before and after the release while checking for constraints on pumping stations or groundwater usage.

Song Ho-seok, the ministry's water resources policy director, said the decision accounts for current algae conditions and heat waves in the lower river region. He added that the department will maintain close communication with local communities to ensure minimal disruption to residents' water usage.

The ministry has already consulted with the Nakdong River Nature Restoration Public-Private Council and local residents regarding the operation. If algae spreads further, authorities intend to pursue a plan to sequentially open all eight weirs along the river.