(ATTN: ADDS water level data near inter-Korean border at bottom)
SEOUL, Aug. 5 (Yonhap) -- Damage from the heavy rain that has pounded South Korea's metropolitan and central regions continued to increase Wednesday, prompting officials to open the floodgates at a major dam for the first time in three years.
The downpours had killed 15 and left 11 missing as of 4:30 p.m., according to the Central Disaster and Safety Countermeasure Headquarters. A total of 1,610 residents, or 975 households, were forced to leave their homes, with two-thirds of them based in the provinces of South and North Chungcheong.
Reports of damaged properties continued to rise, with 4,713 private and public facilities being affected by the downpour. Some 1,300 houses were submerged or buried, while damage was also reported at 899 warehouses and cattle sheds.
In addition to buildings, 1,016 roads and bridges also suffered damage from the heavy rain. A total of 313 landslides were reported, and essential facilities, such as waterworks, sewage lines and railways, were also affected.
Damage was also reported at a combined 8,033 hectares of agricultural land, and some 300,000 cattle were killed, according to the ministry of agriculture.
To restore damaged facilities and help evacuees, the government has mobilized more than 48,800 rescue and volunteer workers as well as nearly 5,800 pieces of heavy equipment, such as excavators and water pumps.
While around 55 percent of damaged facilities have been temporarily restored, 37 roads, including Jamsu Bridge, which connects the southern and northern parts of the Han River in Seoul, remained closed. Six rail routes -- including Chungbuk, Taebaek and Yeongdong -- were partially or completely restricted.
Entry bans remained in place at 349 trekking routes at 13 national parks as well as 16 underpasses and 93 parking lots adjacent to streams and rivers to prevent accidents.
To prevent flooding, major dams across the country began to discharge water as water levels quickly rose.
The Korea Water Resources Corp. began to release water from Soyang River Dam in Gangwon Province at 3 p.m. at a speed of 3,000 tons per second.
The plan is forecast to raise water levels at the Han River by up to 2 meters, with the discharged water arriving near Han River Bridge in central Seoul 16 hours later.
But officials said the water is unlikely to cause additional damage. The dam, built in 1973, has discharged water 14 times, with the latest release taking place in August 2017.
In the afternoon, Prime Minister Chung Sye-kyun visited Eomjeong-myeon and Sancheok-myeon in Chungju, North Chungcheong Province. He vowed speedy restoration and support as he checked up on the two counties, where damages were among the heaviest.
Earlier in the day, Chung ordered the Ministry of Interior and Safety to swiftly review a proposal to declare Gyeonggi and Chungcheong provinces as special disaster zones.
Special disaster zones are designated upon requests by provincial governors. When a request is deemed reasonable by the interior ministry, it is then approved by the prime minister and the president.
The government is planning to announce the list of special disaster zones by Friday. Strong candidates include Chungju and Jecheon in North Chungcheong Province, Cheonan and Asan in South Chungcheong Province and Anseong, Icheon and Yeoncheon in Gyeonggi Province, sources said.
Heavy rainfall also put regions near the inter-Korean border on high alert. Water levels rose to an all-time high at the northernmost bridge and dam on the Imjin River.
The water level at Pilseung Bridge, situated near the Southern Limit Line, stood at 13.01 meters as of 10:00 p.m., after peaking at 13.12 meters, according to state-run Han River Flood Control Office.
Water filled up Gunnam Dam, a key flood-control facility on the Imjin, to 39.99 meters high as of 10:00 p.m., after hitting an all time high of 40.14 meters at 9 p.m.
The authorities attributed the water-level hike to heavy regional downpours and North Korea's release of water from its own Hwanggang Dam, without prior notification.
Local municipalities of Paju and Yeoncheon, Gyeonggi Province, issued an emergency evacuation order to the residents in lowlands, citing rising river levels.