Seoul City Issues 'Attention' Level Algae Warning Upstream of Jamsil Submerged Weir on Han River

[Asia Economy Reporter Lim Cheol-young] As of 5 p.m. on the 24th, the Seoul Metropolitan Government announced that it has issued an algae warning at the 'Interest' level for the first time in six years since 2015 in the upstream area of Jamsil Submerged Weir (water source section).

The warning area is the upstream of Jamsil Submerged Weir, spanning from Jamsil Bridge to Misa Bridge.

This Interest level warning was issued following the monitoring results on the 23rd, where the blue-green algae cell count at Misa Bridge and Gangdong Bridge points exceeded the 'Interest' level warning criteria (1000 cells/㎖) twice consecutively, after the algae concentration at all four points in the water source section exceeded the standard once on the 17th.

The algae warning system, according to the Water Environment Conservation Act, conducts weekly algae monitoring and issues stepwise warnings when blue-green algae cell counts exceed the standard twice consecutively.

In the case of the Han River in Seoul, the area is divided into the water source section (upstream) and the water-friendly activity section (downstream) based on the Jamsil Submerged Weir. When algae measurements at arbitrary points in each section exceed the standard twice consecutively, a warning is issued for the entire section.

Accordingly, Seoul is promptly responding by disseminating the situation to the Waterworks Headquarters, Han River Headquarters, and autonomous districts simultaneously with the issuance of the algae Interest level warning, strengthening water purification treatment, dispersing algae in dense green algae areas, intensifying patrols of the Han River and tributaries, and enhancing water quality management at water reclamation centers.

Additionally, all six Arisu Water Purification Centers in Seoul are equipped with advanced water treatment facilities using ozone and activated carbon, enabling the supply of safe tap water to citizens even during algae warnings in the water source section by coping with water quality changes caused by algae in the intake water.

Han Yoo-seok, Director of the Water Circulation Safety Bureau, explained, “Due to the rain brought by Typhoon Omais (Typhoon No. 12) and the recent easing of the heatwave, green algae is expected to be significantly alleviated. However, we will closely monitor weather conditions and algae spread and respond swiftly to prevent any inconvenience to citizens.”