Saving Sillahalla, the proposed hydroelectric project site in the Nilgiris

For the last few months, residents of Bellathycombai village near Manjoor in the Kundha taluk of the Nilgiris district have been a worried lot. The Adivasi residents have been reporting strange explosions along River Sillahalla — the proposed project site of the Sillahalla Pumped Storage Hydroelectric Project.

While officials of the Tamil Nadu Generation and Distribution Corporation (Tangedco) claim that the explosions should not be a cause for worry, arguing that they were conducting site-stability tests for getting approval for the project from the Geological Survey of India (GSI), residents argue that the government has little regard for their concern over safety. “As we are the ones who would be most affected by this project and at risk from any calamity that may arise out of a hydroelectric power project, we should be informed about the nature of work being undertaken at the site,” said a resident of Bellathycombai.

Residents of the village and 30 other areas which would be most affected by the project have grown increasingly frustrated with the government over its lack of transparency. The Tamil Nadu Pollution Control Board (TNPCB) scheduled a public consultation meeting in March this year, but cancelled it all of a sudden, without announcing a fresh date. Residents and activists feel the last-minute cancellation was a ploy to buy more time for the implementation of the project because environmentalists had planned a large-scale protest at the meeting. Despite assurances from Collector Lakshmi Bhavya Tanneeru that the project would be implemented only with the unanimous consent of local communities, there have been protests by residents and local activists.

Opposition to the project

The ruling DMK seems to have reconsidered its opposition to the project, as current Chief Minister M.K . Stalin had opposed the project when it was proposed by the Jayalalithaa government in 2013. Local communities along River Sillahalla have mobilised in large numbers to protest against its implementation. While the Balocola and Ithalar village panchayats passed resolutions against the project, residents staged several demonstrations.

Recently, hundreds of residents took part in ‘Sillahalla kaavadi’ and offered prayers at a temple at Manjoor against the project’s implementation. Arun Bellie, who is part of the movement spearheading the opposition to the project, says awareness is being created among local communities about its pitfalls. “At the moment, we are ensuring that as many people as possible have access to all the facts about the project,” he said.

Activists have also filed requests with the government under the RTI Act for details about the project and explosives being used at the site. “So far, there has been no response from the government,” says M. Sivalingam, of the Sillahalla Protection Committee and Farmers’ Association.

Venugopal Dharmalingam, honorary director of the Nilgiri Documentation Center (NDC), has written to the UNESCO regional head urging intervention. “The district is the most advanced area of the biosphere, being one of the top tourist destinations [over 3 million visit the Nilgiris in a year] in the country. Among other things, the tiny district contributes some 850 MW of hydro electricity to the State through 14 dams, mostly located within the Nilgiri Biosphere Reserve before it was constituted. It has long been agreed that the Nilgiris had saturated its hydro power capacity,” the letter reads.

“In these circumstances, there have been proposals since 2007 to set up more pumped storage projects in the Nilgiris. Now, suddenly, there is a rush to proceed with the 1,000-MW Sillahalla project in two stages in the Kundah ranges in the south-western part of the Nilgiris. More projects have also been proposed in the western parts, which are mostly Protected Areas. The proposed sites fall in the Core Zone of the Nilgiri Biosphere Reserve where all such activities are prohibited.”

“As a major stakeholder, we would urge your esteemed organization/committee to investigate the matter on priority and take up with the officials/institutions concerned any violation of the biosphere norms and conditions. Complacency could lead to similar attempts in other parts of the Nilgiri Biosphere Reserve,” the letter says.

No transparency

Director of the Tamil Nadu Chapter of the People’s Legal Forum, K. Vijayan , says residents of Manjoor and surrounding areas are aware of the negative impact of the Sillahalla project. Mr. Vijayan wondered why the government had allowed preliminary work at the project site to begin without public consultations. “When the government claims that the project will not proceed without public consensus, what is the need for building roads to the project site, not to mention the use of explosives, before the public consultation is completed,” he asks.

According to an estimate, the Sillahalla Pumped Storage Hydroelectric Power Project will cost the government more than ₹5,843 crore. The project envisages the construction of a 82-metre-high, 327-metre-wide concrete gravity upper dam across River Sillahalla and the construction of a concrete lower dam along River Kundha, measuring 112 metres in height and 470 metres in width. The project also proposes the construction of a number of tunnels to pump water between the lower and upper dams to produce 1,000 megawatts of electricity.

Residents are worried about loss of livelihood from submergence of farmland, and their safety. Mr. Sivalingam told The Hindu that the region is home to a number of dams, including Upper Bhavani, Mukurthi, Emerald, Geddai, and Avalanche. “These dams were constructed when there were very few human habitations in the area. So, when they submerged the land around, there was no significant impact on human communities. However, a Sillahalla dam would destroy thousands of acres of farmland and forest areas,” he said. However, the Tamil Nadu Green Energy Corporation Limited (TNGECL) has sought to allay the fears of people, stating that while 766 acres of private, government and forest land would need to be acquired for the project, “no homestead would be affected.”

“It is shocking that the project is even being considered, as the government itself has stated that the areas surrounding Sillahalla River are prone to landslips. If this dam is constructed, explosives will have to be used and large tunnels would need to be constructed, further destabilising the region and increasing the chances of landslips,” Mr. Sivalingam said.

The residents also fear the project will be rushed through without proper clearance, as has been the case with other projects in the district. 

‘Studies carried out’

According to the TNGECL statement, as part of a Comprehensive Environment Impact Assessment (CEIA), studies of baseline data on air, water, soil, and noise have been carried out for three seasons — pre-monsoon, monsoon, and post-monsoon. “The Environment Impact Assessment/Environment Management Plan (EIA/EMP) Report was prepared. It covered all aspects and mitigation measures during construction and operation phases, and was submitted to the District Environmental Engineer for conducting a public hearing,” the statement said.

It added that clearance on hydrology was obtained and pre-DPR clearance is still being pursued with the 12 Directorates of the Central Electricity Authority of India (CEA), the Central Water Commission (CWC), the Central Soil and Minerals Research Station (CSMRS), and the Geological Survey of India (GSI).

Mr. Bellie says residents’ anxiety has become heightened as none of their concerns over smaller projects in the past had been addressed. “The laws governing the implementation of such projects exist for very important reasons. Till date, we have received no information on the clearance obtained by the company for the use of explosives at the project site,” says Mr. Bellie. “The impact assessment should have been conducted and the contents of the assessment should have been made public,” he says. He said such a blatant disregard for the government’s own laws and regulations could affect people’s trust in the government. “In the Nilgiris, residents face many hassles in getting building permits for houses, roads, and other infrastructure. However, it seems the government can flout the rules and undertake construction of a project even before getting the mandatory clearance,” he says.

Indeed, the area has had its share of tragedy, including a major landslip in nearby Geddai in 1990, when 36 people were killed. Gokul Halan, a hydro-ecologist based out of the Nilgiris, says the lithological make-up of the Nilgiris makes it susceptible to vibrations by tunneling and blasting. 

He also points out that while the Nilgiris is classified under Seismic Zone II (low seismicity), the district is not seismically inert. “The presence of significant lineaments such as the Moyar Fault (to the north) and the Bhavani Shear Zone (to the south) introduces seismic and structural vulnerabilities. These tectonic features are capable of reactivation under stress such as reservoir impoundment and excavation-induced vibrations. Furthermore, anthropogenic activities, including reservoir-induced seismicity and high-pressure tunnelling through jointed terrain, can destabilise pre-existing weaknesses in the rock mass. This elevates the potential for ground subsidence, slope failure, and localised seismic events,” he says.

The Nilgiris has also been at the centre of India’s worst landslips in the last 150 years, including in 2009, when over 1,500 landslips occurred between November 10 and 15, resulting in over 80 deaths and damage to essential infrastructure, points out Mr. Halan.

“The proposed Sillahalla project entails extensive tunnelling, excavation for surge shafts, and the construction of reservoirs across a faulted terrain. These interventions are likely to disturb the geological equilibrium by inducing subsurface vibrations and potential seismicity, increasing water ingress into jointed rock zones, altering groundwater recharge patterns and raising pore water pressures, especially during the monsoon,” he adds.

Wildlife likely to be affected

The project site is also located in proximity to the Mukurthi National Park and the Mudumalai Tiger Reserve, say conservationists. In the last few decades, the land between the two national parks has been frequented increasingly by endangered species like tigers. N. Mohanraj, a Nilgiris-based conservationist, says the submergence of land surrounding the stream will mean more bottlenecks for the wildlife to traverse while moving between different habitats, potentially leading to populations becoming cut off from each other.

“It is laughable that in the Nilgiris, where plastic is banned and there are curbs on the influx of tourists, such an environmentally destructive project is even being planned,” says Mr. Vijayan, adding that the use of explosives in the area could impact the homes and livelihoods of Adivasi communities. Environmentalists have also called for the EIA to be shared with the public. Priya Davidar, a conservation biologist, says a comprehensive EIA should look at whether the area that will be submerged by the dam is being utilised by wildlife to move between different habitats. “This will stop members of the public from speculating on the total extent of the dam…”