Mangan Landslide Sparks Downstream Alerts Across Sikkim and North Bengal as Teesta Normalises Amid Lingering Vulnerabilities

KalimNews, September 7, 2026, Mangan : In the early hours of Sunday, a massive landslide tore through Sikkim’s Mangan district, partially damming the Teesta and Chyakoong rivers and immediately triggering cross-border emergency alerts for downstream communities across Sikkim and northern West Bengal. The incident occurred along a newly cut section of the Naga-Tosa Road in the Naga Forest area, opposite the Theng Tunnel and OC Bhir within the Chungthang subdivision. A substantial portion of the mountain slope gave way, dumping heavy volumes of earth, rock, and rubble into the confluence of both rivers. The blockage led to an alarming upstream accumulation of water, prompting immediate administrative concern. While no casualties or injuries have been reported, authorities within the jurisdiction of the Mangan Police Station are continuing to evaluate the extent of property and infrastructure damage.

Following the morning obstruction, the District Administration of Mangan swiftly dispatched a joint inspection team—comprising Shri Karma D. Bhutia, Joint Director-cum-DPO of DDMA Mangan, alongside Shri Chandan Chhetri, SDPO Chungthang, and personnel from the local police—to conduct a comprehensive ground evaluation opposite the Theng Tunnel. According to their assessments, the natural channel of the Teesta River, initially constrained by debris, has steadily loosened and opened up, allowing water to discharge at a normal and regulated pace. The immediate threat of an abrupt water release or severe downstream flash surge has substantially lessened relative to the morning hours. Nonetheless, while the main channel of the Teesta has largely resumed regular flow, the Chyakoong River remains partially constricted by landslide debris. Furthermore, downstream water levels in parts of the Teesta have experienced significant surges—momentarily running above the danger zone—due to high-volume releases from upstream dams, including the Dikchu Dam. As a precautionary measure, response units from Chungthang Police and the DDMA remain deployed on-site to ensure uninterrupted 24/7 surveillance of water levels and slope stability.

In response to the shifting hydrological situation, the District Collector of Mangan released an advisory reminding riverside communities that public safety remains paramount, stating: “They are advised to remain vigilant, avoid venturing near riverbanks, and voluntarily move to safer, higher locations as a precautionary measure until full clearance operations are completed.” Addressing the evolving situation on the ground, an administrative source noted, “The overall condition along the river stretch remains stable and normal, and the threat of sudden water release or flash surges downstream has significantly reduced compared to the morning hours. The police and the personnel of the district disaster management authority have been deployed on-site to maintain 24/7 surveillance of the river levels and slope stability.” The Sikkim State Disaster Management Authority (SSDMA) has simultaneously urged the public to exercise restraint, stay calm, and avoid circulating unverified videos, claims, or speculative rumours across social media platforms.

The alert from Sikkim reverberated downstream into West Bengal, setting administrative machinery in motion across Kalimpong, Jalpaiguri, and Cooch Behar districts. Authorities carried out public announcements through loudspeakers along riverside settlements, directing families in low-lying pockets to relocate to safer areas. Explaining the ground preparations, an official of the Jalpaiguri district administration stated, “The flood control room of the state irrigation department is functioning round the clock. Also, sandbags have been readied to prevent erosion along the riverbank. If there is any rise in water levels in upper catchments of the Teesta hills, fresh alerts would be issued.” Sandbag barriers were fortified along vulnerable banks, including Domohoni in Jalpaiguri’s Mainaguri block, to stave off bank erosion.

The regional water crisis has been further compounded by an unresolved blockage along the Rangbhang River in Mirik subdivision of Darjeeling district. A landslide that occurred late last week at Mirik Busty-II dumped vast mounds of earth and boulders into the riverbed, creating an artificial dam-like obstruction that has halted regular discharge and created an unnatural reservoir. In response, the Darjeeling district administration evacuated 124 individuals across 33 families from Labarbotay and Lower Palzar Gaon under the Pahila Gaon School Dara-II panchayat, housing them at the Lepcha Community Hall in Mirik with full food and medical aid. Specialist disaster response personnel from the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), and the Arjun Vahini disaster task force remain on-site inspecting the debris and tracking water accumulation. Darjeeling MP Raju Bista, who reviewed the affected ground in Mirik, underlined the gravity of the impasse in a statement, warning: “This poses a serious risk of water accumulation and a possible sudden overflow, which could threaten nearby settlements, roads and public infrastructure.” Across both states, emergency agencies and disaster management bodies continue to advise riverside inhabitants to avoid riverbanks and rely exclusively on verified government alerts.