A reported glacial lake outburst at Sintaphu Lake in Bhutan’s northern Gasa district has triggered flooding, damaging infrastructure and raising concerns for communities downstream. The floodwaters have washed away the popular Gasa Tshachu hot spring complex beside the Mo Chhu and destroyed a section of the Punakha-Gasa Secondary National Highway.
The road near the 31.85-kilometre point has been completely washed away and remains closed to all traffic until further notice, disrupting access towards Laya, one of Bhutan’s remote highland settlements. The sudden release of water was reported on Thursday evening, October 29, with floodwaters reaching Taktsemakhang at around 8.15 pm. Authorities activated warning sirens and evacuated people from potentially vulnerable areas as a precaution. No casualties had been reported as of Friday morning, October 30.
The incident also prompted precautionary warnings for communities along the Sankosh River in neighbouring Indian states of West Bengal and Assam, as the Mo Chhu eventually joins the Pho Chhu to form the Punatsangchhu, which flows into India as the Sankosh. Sintaphu is among Bhutan’s 17 potentially dangerous glacial lakes and has been under scientific monitoring. Authorities are assessing the cause of the reported outburst, the volume of water released and the full extent of the damage.
Travellers have been advised to postpone non-essential journeys towards Gasa and Laya or confirm alternative arrangements before departure. Monitoring of downstream river conditions and the safety of vulnerable communities remains a priority.