Dam Safety

Dam associated with 1.2 GW Teesta Stage III hydroelectric project bursts in India

Dam associated with 1.2 GW Teesta Stage III hydroelectric project bursts in India

Teesta Urja Dam in India’s Sikkim state, which impounds Lohnak Lake and supplies water for the 1.2 GW Teesta Stage III hydroelectric project, suffered massive damage due to flash flooding on Oct. 4, according to multiple news agencies.

In addition to washing away the dam and some associated structures, the entire powerhouse was under water due to the flooding.

The Teesta Stage III scheme consists of a 60-meter-high concrete-faced rockfill dam with two tunnel spillways, a reservoir flushing tunnel, two desilting chambers, a headrace tunnel and surge shaft, along with two pressure shafts. The underground powerhouse contains six 200-MW turbine-generator units.

The South Asia Network on Dams Rivers and People reported that the cause was a glacial lake outburst flood (GLOF) that originated at South Lhonak Glacial Lake just after midnight on Oct 4, 2023, and washed away the dam. Per the network, the Central Water Commission (CWC) reported early on the morning of Oct. 4 that there was cloud burst at the site of the lake burst, and the cloud burst could have played the role in triggering the lake burst.

The project is owned by Sikkim Urja (formerly Teesta Urja). Per reports, none of the workers at the site were injured.

The project was commissioned in February 2017. At that time, Teesta Stage III was reported to cost more than US$1.4 billion to develop.

Teesta Urja was formed to develop the project and has a build-own-operate-transfer contract for 35 years, after which the project will be returned to the government of Sikkim.