On the night of May 30-31, 2025, a catastrophic cloudburst unleashed a 35-40-foot surge in the Teesta River, transforming the tranquil valleys of Lachen, Sikkim, into a disaster zone. The floodwaters obliterated roads, snapped bridges, and left the region completely cut off from the outside world. Among the worst-hit was an Indian Army camp in Chaten, where a landslide buried three soldiers alive, with six more reported missing.
The disaster was compounded by weeks of incessant rainfall, which had already triggered landslides across the Mangan district. By June 1, the Sikkim government had officially declared the situation a “disaster” under the Disaster Management Act, 2005, a rare move that signaled the severity of the crisis.
War Room at Tashiling: The Race Against Time
As the floodwaters receded, revealing the extent of the devastation, Chief Secretary Vijay Bhushan Pathak convened an emergency meeting at the Tashiling Secretariat in Gangtok. The agenda was clear: immediate relief and long-term rehabilitation for Lachen, one of the areas hardest hit.
Chaired by Samdup Lepcha, Minister and MLA of Lachen-Mangan, the meeting brought together top officials, disaster response teams, and representatives from the Lachen Dzumsa, the traditional governing body of the region. Their demands were urgent:
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Temporary suspension bridges to reconnect isolated villages.
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Restoration of power and mobile networks is critical for coordination.
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Steady supply of food, medicine, and fuel to prevent shortages.
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Drone-assisted damage assessments to map high-risk zones.
The Chief Secretary assured that all necessary funds and resources would be fast-tracked, but the challenges were immense. The BRO (Border Roads Organisation) was already working around the clock to clear debris, but with multiple landslides blocking key routes, progress was slow.
Helicopters, Heroes, and Heartbreak
With roads impassable, the Indian Air Force (IAF) launched “Operation Lachen Reach”, deploying Mi-17 helicopters to airlift stranded civilians and drop emergency supplies. Among those rescued were 33 people, including two American tourists, who had been trapped in Chaten since the landslide.
On the ground, NDRF teams waded through sludge to search for survivors, while Army engineers carved out temporary footpaths to reach cut-off villages. By June 7, the IAF had evacuated 76 Army personnel and 113 tourists, marking the end of the most critical phase of the rescue.
But the human toll was undeniable. Families in Lachen mourned the loss of their homes, while the Lachen Dzumsa pleaded for faster aid delivery. “We need permanent solutions, not just temporary fixes,” said a Dzumsa representative. “Our people cannot keep living in fear of the next flood”.
The Science Behind the Disaster
The Teesta River’s fury was no freak accident. Scientists point to climate change as a key driver, with rising temperatures accelerating glacial melt and destabilizing mountain slopes. Just eight months earlier, in October 2023, a Glacial Lake Outburst Flood (GLOF) from South Lhonak Lake had wiped out the Teesta III dam, killing 55 people and displacing thousands.
A 2025 study in Science revealed that the moraine holding South Lhonak Lake had been shifting by 15 meters per year, a clear warning sign that was ignored until it was too late. The same study warned that future GLOFs are inevitable unless monitoring improves.
What Comes Next?
The Sikkim government now faces a dual challenge: short-term recovery and long-term resilience.
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Rebuilding smarter: Engineers are considering climate-resistant bridges and elevated roads to withstand future floods.
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Early warning systems: IoT sensors along the Teesta could provide real-time flood alerts.
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Community-led rehabilitation: The Lachen Dzumsa is advocating for the integration of indigenous knowledge into disaster planning.
But the biggest question remains: Will Sikkim’s fragile Himalayas continue to bear the brunt of unchecked development? With hydropower projects like Teesta-V repeatedly damaged by landslides, activists argue that it’s time to rethink infrastructure in the region.
A Global Warning
The Lachen flood disaster is not just Sikkim’s problem; it’s a warning for all mountain communities. As glacial lakes grow and weather patterns worsen, the Himalayas are becoming a ticking time bomb.
“The Teesta’s fury is a wake-up call,” says Dr. Ashim Sattar, lead author of the Science study. “If we don’t act now, next time could be even deadlier“.
For now, the people of Lachen are picking up the pieces. But their struggle is far from over.
