Another dam has collapsed at the Teesta power project in Sikkim within a year. The Teesta Stage 5 dam of the National Hydroelectric Power Corporation (NHPC) was damaged by a landslide on Tuesday morning, though no casualties have been reported as the power station had been evacuated recently due to frequent landslides.
NHPC’s expert team is currently assessing the damage, evaluating losses, and planning remedial measures. The Stage 5 dam had been out of operation since the glacial lake outburst in October 2023, which had previously damaged the Teesta Stage 3 dam of Sikkim Urja Ltd. This event, caused by a cloudburst, led to massive flooding that affected North Sikkim’s Mangan district.
Such floods are often triggered when glacial lakes formed by melting ice accumulate water behind weak moraine dams, which can fail suddenly, releasing large volumes of water and causing downstream devastation.
The landslide on Tuesday impacted the hoist structure of the tail race tunnel (TRT) outlet and the GIS building (high-voltage substation) at NHPC’s 510 MW Teesta-V Power Station, which is currently not operational and undergoing restoration after the October 2023 flood. Last October, NHPC reported that both the Teesta-V power station (510 MW) and the Teesta-VI HE Project (500 MW) were affected by floods in Sikkim’s Lachen Valley.
Sikkim has experienced severe weather this year, with at least six people killed and around 2,000 tourists stranded in June due to landslides and floods following 36 hours of heavy rainfall. The monsoon season (June-September) has brought 32% more rainfall to Sikkim than usual, compared to the 4% above normal precipitation across India, according to the India Meteorological Department.
Last year, floods triggered by a Himalayan glacial lake outburst resulted in 179 deaths in Sikkim.
