In March 1991, an environmental disaster occurred in Gumi, a city located upstream of the Nakdong River in South Korea, when the toxic chemical phenol leaked into the river. The contaminated water flowed downstream, and the first signs of trouble appeared in Daegu, South Korea’s third-largest city, which relies on the river as a source of drinking water. During the chlorine disinfection process at a water treatment plant, the phenol reacted to form chlorophenol, causing severe abnormalities in the taste and odor of the tap water. This incident is regarded as one of the most notorious environmental disasters in South Korea’s history, sparking intense public outrage and leaving a profound social impact.