South Korea is currently grappling with a challenging mix of weather extremes, as the start of September 2025 has brought both relentless heatwaves and damaging floods. Chuncheon, a city in Gangwon Province, has found itself at the epicenter of these dual crises, facing not only the aftermath of heavy rainfall and landslides but also sweltering temperatures that have blanketed much of the country. According to reporting from Kw News, city officials in Chuncheon confirmed on September 2 that the area had suffered significant flood damage and landslides in the early hours, the latest in a string of weather-related disruptions that began in June.
These developments come as South Korea’s meteorological agency warns of continued high temperatures and sporadic rain across the nation. On September 1 and 2, the heatwave showed no signs of letting up, even as floodwaters lingered in various regions. Major cities such as Seoul, Busan, and Chuncheon recorded daytime highs soaring to 32 degrees Celsius, making daily life uncomfortable and complicating recovery efforts in areas hit by floods. The Korean Meteorological Administration forecasted that the heat would persist, with morning lows ranging from 20 to 26 degrees Celsius and highs between 28 and 32 degrees Celsius across the country.
For Chuncheon, the situation has been especially fraught. The city’s troubles began in the first half of June 2025, when torrential rains led to widespread flooding and triggered landslides in both urban and rural districts. Local authorities responded swiftly, conducting four separate rounds of inspections and investigations to assess the extent of the damage and coordinate emergency responses. As Kw News reported, these efforts confirmed the severity of the flood and landslide damage, prompting ongoing monitoring and disaster mitigation measures by the city government.
Yet, the challenges have not been limited to physical destruction. The unusual weather patterns—marked by a shortened monsoon season and record-breaking heat—have also disrupted water quality in Chuncheon. In an unexpected twist, the city reported that the combination of high temperatures and brief but intense rainfall triggered an early outbreak of algal blooms (often referred to as green tides) in local reservoirs, raising concerns about the safety of the municipal water supply.
Algal blooms can be more than just unsightly; they often produce unpleasant odors and can interfere with water purification processes, potentially compromising the safety and palatability of tap water. Recognizing these risks, Chuncheon’s water authorities sprang into action. From the earliest signs of algal proliferation near the Chuncheon Dam in late June, city officials activated a multi-stage emergency response plan at both the Soyang and Yongsan water treatment plants. This included close coordination with Korea Hydro & Nuclear Power to adjust water discharges from the Uiam and Chuncheon dams, a move aimed at diluting concentrations of algae-forming nutrients.
In addition to these upstream interventions, the city enhanced its water treatment protocols. Operators began adding powdered activated carbon to the purification process, a step designed to absorb odor-causing compounds and improve overall water quality. At the final stage of treatment, chlorine levels were increased to ensure any remaining contaminants would be neutralized. These technical measures were bolstered by a rigorous monitoring regime: beyond the regular inspections conducted by the Gangwon Institute of Health and Environment, Chuncheon implemented its own testing schedule, with in-house water quality checks twice a week and independent laboratory analyses once a week, totaling four detailed inspections per week.
The results of these efforts have been reassuring. According to city officials quoted by Kw News, recent continuous tests at the Yongsan water treatment facility confirmed that concentrations of odor-causing substances from algal blooms had fallen below regulatory limits. As a result, the use of activated carbon was discontinued, and the city began considering a phased return to normal water treatment operations. A city spokesperson explained, "Based on the stabilization of raw water quality, we are reviewing a step-by-step normalization." Such comments underscore the city’s cautious optimism that, despite the ongoing weather challenges, residents’ access to safe drinking water has been preserved.
Meanwhile, the broader weather picture across South Korea remains unsettled. The Korean Meteorological Administration forecasted that rain would continue to fall intermittently across the country on September 2, particularly in the southern and central regions. While some areas—such as the southern parts of Gyeonggi Province and the inland and mountainous regions of Gangwon—were expected to see rain taper off by mid-morning, others, including the southern provinces and Jeju Island, could expect showers to persist into the afternoon. Predicted rainfall totals ranged from 10 to 80 millimeters, with localized downpours exceeding these averages in places like Daejeon, Sejong, and South Chungcheong.
Despite these rainy spells, the heatwave showed little sign of abating. Seoul, Chuncheon, and Busan all faced forecasted highs of 32 degrees Celsius, while other cities such as Incheon, Daejeon, and Gwangju hovered close behind at 30 or 31 degrees. Even Jeju, known for its milder maritime climate, was expected to reach 31 degrees. The result? A country simultaneously battling the risks of heat-related illnesses and the lingering dangers posed by floodwaters and unstable slopes. Fortunately, air quality was expected to remain favorable, with fine dust concentrations at "good" to "moderate" levels, according to the meteorological agency.
The combination of heatwaves and flood damage has created a uniquely challenging environment for South Korean authorities and residents alike. Emergency responders in cities like Chuncheon have had to juggle the immediate demands of disaster relief—such as clearing debris, repairing infrastructure, and supporting displaced families—with the longer-term task of monitoring and safeguarding public health. The city’s experience with early algal blooms is a stark reminder of how climate extremes can interact in unexpected ways, complicating even routine municipal services like water supply.
As September unfolds, all eyes are on the skies—and the rivers. Local governments across South Korea continue to monitor weather developments closely, ready to respond to new emergencies as they arise. For Chuncheon, at least, the worst of the water quality scare appears to have passed, thanks to swift intervention and constant vigilance. Yet, with the rainy season and high temperatures both lingering, the sense of unease remains palpable. The hope is that lessons learned from this summer’s ordeal will better prepare the city—and the nation—for whatever climate surprises may come next.
