Bac Khe 1 hydropower dam in Tan Tien commune of northern Lang Son province collapsed on the afternoon of October 7 following prolonged heavy rainfall brought by Typhoon Matmo, and all residents in downstream areas have been safely evacuated, local authorities reported.
According to Nguyen Manh Tuan, Vice Chairman of the Tan Tien Commune People’s Committee, torrential rains persisted from October 6–7, causing a rapid rise in water levels.
At 9:00 on October 7, water inflow and outflow at the Bac Khe hydropower plant both reached 1,181 cubic metres per second. By noon, both figures had increased to 1,562 cubic metres per second. At approximately 13:30, the Bac Khe 1 dam collapsed.
Located in Bac Khe hamlet, the Bac Khe 1 hydropower plant has an installed capacity of 2.4 MW, a catchment area of 325 sq.km and a reservoir volume of 1.572 million cubic metres. The breach was about 4–5 metres wide and 3-4 metres deep.
Preliminary assessments suggest the dam failure resulted from prolonged heavy rainfall, which caused the water flow to surge to 1,572 cubic metres per second, breaking a section of the concrete at the water intake. The collapse also destroyed the central control room and damaged equipment. No casualties have been reported, though property losses are still being assessed.
Local authorities said that earlier in the morning, competent forces had inspected the dam and detected cracks, indicating a high risk of rupture. Warnings were issued immediately, and roughly 200–300 households in four downstream hamlets were evacuated to safe areas.
Bac Khe 1 is a small hydropower project with a reservoir capacity of about 3–4 million cubic metres. While the collapse and persistent rainfall have caused localised flooding in nearby communes, including That Khe and Trang Dinh, local authorities confirmed that flash floods and landslides have not occurred.
Provincial leaders and emergency forces are currently coordinating efforts to reach the site and implement response measures.
Police, military, medical and rescue teams have been mobilised for evacuation and emergency support. However, access to the affected area remains difficult as several sections of National Highway 3B have been cut off due to severe flooding.
Authorities are continuing to monitor the situation closely and prioritising safety while working to assess damage and prevent further risks.
