A glacial lake outburst flood (GLOF) was reported at Shintaphu Lake in Bhutan’s Gasa district on Thursday evening, triggering precautionary flood alerts in parts of West Bengal and Assam over a possible rise in the Sankosh River. The lake, also known as Shintaphu Tsho, lies below Wakila Mountain in Lungo, Laya Gewog, in the upper reaches of the Mo Chhu river basin and is among Bhutan’s 17 potentially dangerous glacial lakes. The flash flood damaged infrastructure around Gasa Tshachu, a popular natural hot spring, and affected a solar-powered irrigation system and roads in Bhutan.
No deaths or injuries have been reported so far, with the affected area evacuated beforehand. In West Bengal, authorities have moved thousands of residents from vulnerable areas to safer locations, while SDRF and NDRF teams have been mobilised. Alipurduar SP Amit Kumar Shaw said the water flow had eased slightly but a red alert remained in force for the Sankosh river system.
Infrastructure Damaged
The outburst caused significant damage around Gasa Tshachu, with floodwaters washing away infrastructure at the popular hot-spring destination. Bhutan Broadcasting Service reported that the full extent of the damage could not initially be assessed because of darkness and strong currents. Two Bailey bridges may also have been swept away, while Bhutan’s national newspaper Kuensel reported that part of the road towards Laya had been washed away and was impassable, with traffic suspended indefinitely.
A solar-powered irrigation lifting system in Dochhukha-Dzomlingthang-Ritsa Chiwog, under Guma Gewog in Punakha, was partially damaged and stopped functioning. Debris was also reported on a section of the Punakha-Gasa Highway.
Bengal On Alert
The incident has raised concern downstream because the Mo Chhu river system is connected to the wider Sankosh river system, which flows from Bhutan into India. West Bengal Forest Minister and Kumargram MLA Manoj Kumar Oraon urged residents living along the Sankosh in Alipurduar district to move to safer locations.
He warned that a surge could reach Kumargram within around one to one-and-a-half hours and asked residents to cooperate with the administration. Authorities have been closely monitoring areas of North Bengal, including Alipurduar, Jalpaiguri and Cooch Behar, while Assam’s Dhubri district has also been placed on alert. NDRF and SDRF teams have been deployed in vulnerable areas.
Alipurduar Superintendent of Police Amit Kumar Shaw said authorities were coordinating with Bhutanese officials, the district administration and disaster-response agencies. He said around 4,000–5,000 people had been moved into shelters, while more than 6,000 others had been relocated to safer areas.
“There is absolutely no need to panic. The situation is currently under control,” Shaw said, adding that the intensity of the water flow had reduced slightly, although a red alert remained in place for the Sankosh river system. Officials have also arranged essentials including drinking water and dry food at relief centres.
A Recurring Threat
Shintaphu Lake is considered one of Bhutan’s 17 potentially dangerous glacial lakes. A GLOF occurs when water stored in a glacial lake is suddenly released, potentially sending a fast-moving surge carrying water, rocks and debris through downstream valleys.
An official from Bhutan’s National Centre for Hydrology and Meteorology said a water-level monitoring station was operating at Taktsimakhang, although it had not triggered an alert when the initial reports emerged. The exact scale of the latest outburst and its downstream impact remained unclear at the time of reporting.
The latest incident also brings back memories of the major flash flood that struck Gasa Tshachu in August 2021, when the Mo Chhu changed course towards the hot-spring area.
The recurrence highlights the vulnerability of infrastructure and communities situated along steep Himalayan river valleys. With rivers originating in Bhutan flowing into India, timely information-sharing, river monitoring and coordinated evacuation plans remain crucial for communities on both sides of the border.
The Logical Indian’s Perspective
The Shintaphu outburst is a reminder that natural disasters do not stop at national borders. For communities living along Himalayan rivers, an event upstream in Bhutan can quickly create risks downstream in India. The priority must therefore be timely warnings, transparent sharing of hydrological information, well-equipped disaster-response teams and safe evacuation plans that put people’s lives first.
India and Bhutan have a shared interest in ensuring that communities are prepared before a sudden rise in river levels becomes a humanitarian crisis. What more can India and Bhutan do together to strengthen early-warning systems and protect vulnerable Himalayan communities?
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