A glacial lake outburst flood at Shintaphu Lake in Bhutan’s Gasa district has sent a surge of water down the Mo Chhu river. Authorities in West Bengal and Assam have issued flood alerts for areas along the Sankosh river. Bhutan’s state broadcaster, BBS, reported no injuries or deaths, because officials had evacuated the area before the water arrived.
What Happened at Shintaphu Lake
The outburst took place on the evening of Thursday, 29 October 2026, according to reports from Bhutan and India. Floodwater swept through Gasa Tshachu, a popular natural hot spring near the Mo Chhu, and destroyed facilities there. BBS said darkness and the strong flow slowed the assessment of the damage.
Bhutan’s National Centre for Hydrology and Meteorology (NCHM) tracked the Mo Chhu after the outburst, according to EconoTimes. Some Indian reports locate the event at “Lemthang,” which is a place name used in West Bengal alerts, while Bhutanese and wire reports name Shintaphu Lake (also spelled Sintaphu).
Damage Inside Bhutan
Kuensel, Bhutan’s national newspaper, reported that parts of the road leading to Laya village, where the hot springs are located, were washed away. The road has been closed to traffic, and two Bailey bridges may also have been swept away, Outlook India said, citing Kuensel.
NDTV reported that a solar irrigation lifting system in Punakha’s Guma Gewog was partly damaged, according to an official press release, and that debris covered a section of the Punakha-Gasa Highway. It added that floodwater had crossed Srigang in Kabesa Gewog, about eight kilometres from Punakha Dzong. Full damage assessments were still pending.
Alerts and Evacuations in India
Bhutan has informed Indian authorities, and the flood is expected to travel down the Punatsangchhu, which becomes the Sankosh in India. The Central Water Commission’s flood forecast directorate issued a special advisory naming Alipurduar in West Bengal and Dhubri in Assam. NDTV quoted the advisory as saying the water would reach the border in about six to eight hours and could cause a sudden rise in water levels.
In West Bengal, authorities activated the State Disaster Management Team and notified the National Disaster Response Force, Outlook India reported. The same report said more than 10,000 people were moved to shelters and safer places across North Bengal. Residents of the Darjeeling hills, Terai and Dooars were told to stay alert. NDTV also listed Jalpaiguri and Cooch Behar among the districts on watch, and said Cooch Behar warned people living along the Sankosh.
What Officials Said
Darjeeling MP Raju Bista posted an alert on 29 October urging people in the Sankosh catchment to move away from the river and its tributaries. Alipurduar’s Superintendent of Police, Amit Kumar Shaw, told reporters, as quoted by NDTV, that people should not panic and that agencies were on alert. NDTV attributed that comment, and I have not independently verified it.
How a Glacial Lake Outburst Flood Works
A glacial lake outburst flood, or GLOF, happens when the natural barrier holding a glacial lake gives way and releases a large volume of water suddenly. Heavy rain, landslides, avalanches, earthquakes or rapid glacier melt can trigger a breach. Retreating glaciers form many of these lakes, and warming temperatures have sped up that process.
Why the Sankosh Basin Is Watched Closely
Shintaphu Lake lies at the head of the Mo Chhu and is one of 17 glacial lakes Bhutan lists as potentially dangerous, according to Outlook India and Free Press Journal. Reports say Gasa Tshachu was previously hit by a major flood in 2021 when the Mo Chhu changed course.
The Mo Chhu meets the Pho Chhu at Punakha to form the Punatsangchhu, which flows into India’s West Bengal plains and on to the Brahmaputra, according to NCHM’s flood-warning procedure. The Bhutanese has reported that the Punatsangchhu basin holds 11 high-risk lakes, nine in the Pho Chhu and two in the Mo Chhu. NCHM’s warning system, built from 2011 in the Pho Chhu and extended to the Mo Chhu in 2013, uses 10 remote water-level stations and 18 sirens.
Why It Matters
The event shows how a lake high in the Himalaya can threaten villages hundreds of kilometres downstream across an international border. The prior evacuation at Gasa explains why no one was hurt, and it shows the value of early warning and cross-border data sharing. It also adds to concern about glacial lake hazards across the region.
What Happens Next
Authorities will continue to monitor river levels at the border and along the Sankosh. Bhutan will assess the road, bridge and infrastructure damage and clear access to Laya. Indian districts will decide when to lift alerts based on gauge readings. Residents in low-lying areas should follow official advisories and move when told to.
FAQs
What happened in Bhutan?
A glacial lake outburst flood at Shintaphu Lake in Gasa district hit the Mo Chhu on 29 October 2026.
Were there any casualties?
No injuries or deaths were reported, as the area had been evacuated.
Which Indian districts are at risk?
The CWC named Alipurduar in West Bengal and Dhubri in Assam. Other reports list areas of the Darjeeling hills, Jalpaiguri and Cooch Behar.
How many people were evacuated in North Bengal?
Outlook India reported more than 10,000.
What is a GLOF?
A sudden release of water from a glacial lake after its natural barrier fails.
Which river carries the water to India?
The Punatsangchhu, which becomes the Sankosh in India.