The washing away of the dam of the Teesta-III project and damage to the Teesta-V dam in Sikkim because of Lhonak Lake in north-west Sikkim has again brought focus on the series of hydel projects that ‘have been built, are being built and are proposed’ on one of the most dammed rivers in the country.

Sikkim’s biggest hydro power project Sikkim Urja (formerly Teesta Urja) on Wednesday suffered massive damage due to the flash flood on Tuesday night as the dam and the bridge connecting the powerhouse were washed away.

According to authorities, the dam was washed away in 10 minutes after the flash floods hit North Sikkim.

In 2004, the Central Electricity Authority prepared a preliminary feasibility report of 162 hydel projects in the country with an installed capacity of 50,000 MW of power generation of which 10 were to be built in Sikkim with an installed capacity of 1,469 MW.

As the years passed, more projects were added and as per the National Hydropower Development Corporation (NHDC), 47 hydropower projects are in different development stages on Teesta river in Sikkim and West Bengal. Of them, nine have been commissioned, work on 15 dams is going on and another 28 are in the pipeline.

According to a paper on hydel projects in Sikkim published in the World Water Council journal, more than half of the hydel projects are in northern Sikkim, which was most affected by the Wednesday floods. Experts have also pointed out that north Sikkim is prone to landslides triggered by extreme rain events, whose frequency has increased in the recent past across the Himalayan belt, according to various studies by the Pune-based Indian Institute of Tropical Meteorology.

Also Read: Sikkim: 14 dead, 120 missing, bridges, dams, roads washed away in flash flood

All the projects in Sikkim are river projects, in which a channel is created to run the turbine and the water flows back into the river. The dams built are primarily for channelising the water to turbines with limited irrigation potential, unlike big hydro-projects like Bhakra Nangal in Himachal and Sardar Patel Sarovar in Gujarat.

The dams are being built by the Sikkim government in partnership with private operators. The Teesta-III project, which was badly damaged in the flash flood on Wednesday, was built in collaboration with private partners and was commissioned in 2017. It is the biggest run of the river hydel project in Sikkim.

The local activists in Sikkim for long have warned of the adverse environmental and disaster implications for a series of run-of-the-river projects on the 414 km long Teesta River that originated from Punhunri Mountain in north Sikkim.

Jeta Sankrityayan, a retired professor of Economics at North Bengal University and member of the West Bengal Landslide Expert Committee, said the historical records show Teesta river shows its fury every 50 years and the Wednesday event was the biggest after the 1968 catastrophe.

“The impact of rain fury has extenuated due to the construction of dams along the river that block the natural river flow. The complete washing away of the dam at Teesta Urja hydro-power project is an example of that,” he said, attributing the dam collapse to the devastation downstream of the dam.

He said the Sikkim and the Central government should learn a lesson from the tragedy, which has been declared a disaster by the state government, that hydro-power projects of such a mega magnitude would continue to bring catastrophe in Sikkim and some parts of West Bengal located in the downstream.

Gyatso Lepcha, general secretary of Affected Citizens of Teesta (ACT), said the tall claim that the dam of Teesta Urja hydro-power project would be an engineering feat and would be amongst the strongest in the world has turned out to be a big joke jeopardising human lives and properties.

“We knew that this was coming and this has finally proved true. We were warning about this for long but nobody listened,” he said. He added said the Teesta Urja dam could not withhold the water coming from the Lachen and Lachun rivers and burst. “The same can happen with other dams also,” he said, seeking a safety review of all dams in Sikkim.

Vijay Bhusan Pathak, Sikkim’s chief secretary refused to comment on the efficacy of the dams and said the spillover from the lake caused extensive damage to life impacting both human live and properties. “We will review the safety of all dams,” he added.

Teesta Urja, the 1,200 MW power project on the Teesta river is located between Chungthang and Mangan in Mangan district in North Sikkim and is the biggest of nine working hydro projects on the river in Sikkim.

The death toll in Sikkim flash floods has risen to 14 while more than 100 people are missing, the state government confirmed Thursday. 22 army personnel are also among the 102 missing people while 26 remain injured and are seeking treatment following the disaster, triggered by a cloudburst over Lhonak Lake in north Sikkim