South Korea’s capital was issued its first flood alert in nine years, as days of heavy rain threatened river systems in much of the country, including Seoul’s Han River. Most major dams were discharging water, at risk of flooding.

The death toll from the six-day streak of torrential rain stood at 18 as of 5 p.m. Thursday, with 16 others missing, according to the Central Disaster and Safety Countermeasure Headquarters.

One person was killed, another was found without a heartbeat and five were missing after three boats capsized at around 11:30 a.m. near Uiam Dam in Chuncheon, Gangwon Province. A total of eight people were aboard the boats, with one rescued at the scene.

The boats are believed to have been swept through one of the dam’s open gates. The accident happened after a police patrol boat got caught in a wire near the dam and the two other boats worked to salvage it.

More than 800 police officers and firefighters were dispatched to the scene for rescue efforts.

Thursday’s death count was up by three from a day earlier as a body, believed to be of one of three family members who went missing Sunday, was found in Danyang, North Chungcheong Province, and a man in his 50s was found dead in Hongcheon, Gangwon Province, four days after he went missing. The third was the confirmed casualty from the boat accident.

A woman was found dead near a stream in Anyang, Gyeonggi Province, but it was not confirmed if her death was related to the current extreme weather.

The heavy downpour that began Saturday has wreaked havoc in Seoul and Gyeonggi, North Chungcheong, South Chungcheong and Gangwon provinces. The Korea Meteorological Administration cleared heavy rain alerts for most regions at 1:10 p.m. on Thursday, but added that rainfall is likely to start again Friday for most affected areas.

In Seoul, a flood alert issued at 11 a.m. forced major highways across the capital to partly close Thursday. By 4:30 p.m., the water line for the Han River Bridge in central Seoul reached 8.68 meters, exceeding the 8.5-meter level that calls for anti-flood measures.

A flood alert was last issued for Seoul on July 28, 2011. The water level at the Han River Bridge is considered a main barometer for the river’s overall water level.

Rising waters forced Seoul to close multiple sections of Olympicdaero, Seoul Inner Loop, Gangbyeon Northern Highway and Dongbu Urban Expressway to traffic.

The inundated Jamsu Bridge connecting Seocho-gu and Yongsan-gu has also been off-limits for five days straight since Sunday afternoon. By 4:30 p.m. Thursday, the water line for the bridge marked 11.41 meters, surpassing the previous record of 11.03 meters on July 28, 2011.

Eleven of Seoul’s 25 districts, including Yongsan-gu, Gangnam-gu, Seocho-gu and Mapo-gu, were facing flood risks from surging water levels, with many of the districts’ pedestrian and motor roads inundated.

Directly impacting Han River’s water level were discharges from upstream dams, including Soyang River Dam and Paldang Dam, to ease flooding risks in nearby regions.

Soyang River Dam, a key flood defense line for Seoul, opened its floodgates for the first time in three years Wednesday, as continued rain pushed the water level past its limit. The dam has sent up to 3,000 tons of water per second gushing out since opening at 3 p.m. Wednesday.

More people had to evacuate due to the continued rain streak, with thousands more added in Gangwon Province. According to the Central Disaster and Safety Countermeasure Headquarters, more than 4,900 people from 1,598 households were forced to evacuate, and 3,019 people from 952 households have yet to return to their homes.

Property damage also continued. A total of 5,177 incidents have been reported, with 2,617 concerning private property. More than 1,400 residential buildings were flooded, and 1,055 damage reports were filed for barns and storage facilities.

The downpour also flooded 8,065 hectares of farmland. Around 1,043 incidents of damage were reported on roads and overpasses, while 363 streams were flooded and 396 landslides were reported.

Emergency recovery work is around 68.5 percent complete, the central disaster response team said. To repair damaged property, 53,667 civil workers, firefighters, police officers, volunteer workers and military service members have been dispatched with 6,534 excavators and water pumps.

To ensure swift provision of government support funds to the affected regions, officials continued to push to designate Gyeonggi, North Chungcheong and South Chungcheong provinces as special disaster areas, while discussing another supplementary budget aimed at financing recovery efforts.

Democratic Party of Korea leader Lee Hae-chan promised during his visit to Anseong, Gyeonggi Province, that he and his party will work to designate the affected areas as special disaster areas as soon as the damage is verified.

Smaller opposition People’s Party leader Ahn Cheol-soo said in a meeting Thursday that the government should review forming a special supplementary budget to finance recovery efforts at affected areas.

Kim Chong-in, interim leader of the main opposition United Future Party, added force to the need for the extra budget, saying a supplementary budget would be needed if the total damage cannot be handled within the amount left for this year.

By Ko Jun-tae (ko.juntae@heraldcorp.com)