An algal bloom warning was issued at 2pm on August 5 at Paldang Dam on the Han River. With such algae overgrowth recently becoming a serious problem, this is the second time such a warning has been issued in the last two years (August 2012).
Algae growth has accelerated due to a relatively dry rainy season and increases in water temperature, nonpoint source pollutants, and nutrients such as nitrogen and phosphorus. The problem was compounded as water has been retained by the dam for longer periods of time (reservoir release was reduced). Only rain can solve this problem. The Seoul Metropolitan waterworks needs rain, but the sewer system doesn’t want rain. I feel like the father of an umbrella merchant and a fan seller.
In any case, the concentration of geosmin, which is released by bacteria and causes a distinct taste and odor, is currently 400-500 mg/L in the raw water. We are working hard to bring it down to 10 mg/L at the purification plant, with plant workers taking on emergency shifts. The photo below is an image of activated carbon powder mixed with water (black colored), being poured into the reservoir. The odor of the water does not affect public health, but you might smell an “earthy odor” when you take a shower. Water quality has not been affected at all, so don’t worry about drinking it. I’m still drinking the water.