Harmful cyanobacteria falls below threshold for two consecutive tests

Sayeon Lake remains under Attention-level alert

The water intake facility at Hoeya Lake in Cheongyang-eup, Ulju-gun, Ulsan, where an Attention-level algae alert had been in effect. [Ulsan Waterworks Authority]
The water intake facility at Hoeya Lake in Cheongyang-eup, Ulju-gun, Ulsan, where an Attention-level algae alert had been in effect. [Ulsan Waterworks Authority]

The Ulsan Waterworks Authority said Wednesday that the Nakdong River Basin Environmental Office lifted the Attention-level algae alert at Hoeya Lake at 6 p.m. Tuesday, 42 days after it was first issued.

Under the algae alert system, an Attention-level warning is issued when harmful cyanobacteria counts reach 1,000 or more cells per milliliter in two consecutive tests at a drinking water source, and is lifted when counts fall below that threshold in two consecutive tests.

A Sept. 7 test found 270 cells per milliliter at the intake tower and 260 at the spillway. A follow-up test on Monday recorded 360 cells at the intake tower and 210 at the spillway, both below the 1,000-cell threshold for a second consecutive time.

On the basis of those results, the Nakdong River Basin Environmental Office lifted the Attention-level alert at both the intake tower and spillway sites at Hoeya Lake at 6 p.m. Tuesday.

The Attention-level alert at the Banyeon-ri site on Sayeon Lake has remained in effect since it was issued on June 9.


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