Tehri Dam is an earth-and-rockfill dam built on the Bhagirathi River at the confluence with the Bhilangna River in Tehri Garhwal district, Uttarakhand. At 260.5 metres, it is the tallest dam in India and one of the tallest in the world. Completed in 2006, it generates 1,000 MW from its main powerhouse, and the additional 1,000 MW Tehri Pumped Storage Project (PSP) – India's first variable-speed PSP – is now fully commissioned, with its four 250 MW units entering commercial operation between June 2025 and April 2026. The project also supplies drinking water to Delhi and irrigation support to parts of Uttar Pradesh, but remains one of India's most controversial dams due to large-scale displacement and seismic zone concerns.
Quick Facts
| Parameter | Details |
|---|---|
| Dam Name | Tehri Dam |
| River | Bhagirathi (at confluence with Bhilangna) |
| State | Uttarakhand |
| District | Tehri Garhwal |
| Type | Earth-and-rockfill dam |
| Height | 260.5 metres (855 feet) |
| Length | 575 metres |
| Reservoir Name | Tehri Lake |
| Reservoir Capacity | 3.54 billion cubic metres (2.615 MAF) |
| Year of Completion | 2006 |
| Built By | THDC India Limited (formerly Tehri Hydro Development Corporation) |
| Purpose | Hydropower, irrigation, drinking water supply, flood moderation |
Location and River Context
The Bhagirathi is one of the two main headstreams of the Ganga (the other being the Alaknanda). It originates from the Gaumukh glacier at the snout of the Gangotri Glacier and merges with the Alaknanda at Devprayag to form the Ganga.
Tehri Dam sits in the upper Ganga basin within the fragile Himalayan geological zone (Seismic Zone IV/V). This gives the project special ecological, cultural, and disaster-risk significance that sets it apart from peninsular river dams.
Tehri Hydro Power Complex
Tehri is not a single dam project. It is a multi-stage hydroelectric complex managed by THDC India Limited.
| Component | Capacity | Status |
|---|---|---|
| Tehri Dam (Stage I) | 1,000 MW | Operational (2006) |
| Koteshwar HEP | 400 MW | Operational (2012), downstream balancing dam |
| Tehri PSP (Stage II) | 1,000 MW | Operational (2025–26); India's first variable-speed PSP, 4 x 250 MW |
The 1,000 MW Tehri Pumped Storage Project is significant for India's energy transition. Pumped storage acts as a "grid battery" — pumping water uphill during low-demand hours and releasing it for peak-hour generation. This helps balance the intermittency of solar and wind power.
Total complex capacity when fully operational: 2,400 MW.
Significance
Power Generation
The main Tehri Dam powerhouse generates 1,000 MW, and the downstream Koteshwar project adds 400 MW. With the PSP now fully commissioned, the complex produces 2,400 MW total, making it one of India's largest hydroelectric installations.
Irrigation
The project provides irrigation support to approximately 270,000 hectares in western Uttar Pradesh through the Upper Ganga Canal system. Regulated releases from Tehri ensure water availability during non-monsoon months.
Drinking Water Supply
Tehri supplies approximately 500 million gallons per day of drinking water to Delhi and other towns in Uttar Pradesh and Uttarakhand. This makes it strategically critical for the National Capital Region's water security.
Flood Moderation
The 3.54 BCM reservoir capacity moderates Bhagirathi floods, reducing downstream flood risk in the Ganga basin during the monsoon.
UPSC Relevance
Prelims (GS Paper I): Tallest dam in India; river-dam matching (Bhagirathi-Tehri); dam-type identification (rockfill vs gravity); Ganga headstream geography.
Mains (GS Paper I — Geography; GS Paper III — Environment, Disaster Management):
- Development vs environment: displacement, ecological costs of large Himalayan dams
- Multipurpose river valley projects and energy security
- Seismic risk and infrastructure in Himalayan zone (NDMA guidelines)
- Pumped storage hydropower and India's renewable energy integration
- River basin management in the upper Ganga system
- Tehri as a case study for displacement and rehabilitation policy
Environmental and Social Impact
Tehri Dam is one of India’s most debated infrastructure projects. The reservoir submerged the old Tehri town and displaced approximately 100,000 people from over 100 villages. The anti-dam movement, led by Sunderlal Bahuguna (also prominent in the Chipko Movement), argued that the project imposed unacceptable social and ecological costs on Himalayan communities.
The dam sits in Seismic Zone V, the highest earthquake risk category in India. The 1991 Uttarkashi earthquake (6.8 magnitude) and the 1999 Chamoli earthquake renewed fears about catastrophic dam failure in the tectonically active Garhwal Himalaya. Proponents counter that the dam was designed to withstand a magnitude 8.5 earthquake.
Ecologically, the dam altered the Bhagirathi's natural flow regime, affecting downstream aquatic ecosystems and reducing sediment transport. Environmental groups have advocated for mandatory ecological flows and improved rehabilitation of displaced families, many of whom remained inadequately compensated decades after displacement.
Displacement and Rehabilitation
The Tehri project is a textbook case of development-induced displacement in UPSC Mains. Key facts:
- Approximately 100,000 people displaced
- Old Tehri town submerged entirely
- New Tehri town built as a replacement settlement
- Rehabilitation criticised by civil society as slow and incomplete
- Sunderlal Bahuguna led prolonged protests against the project
A balanced Mains answer should state the trade-off clearly: large public benefits in power, water, and irrigation were pursued at very high social and ecological cost to local Himalayan communities.
Comparison with Other Major Indian Dams
| Dam | River | State | Height | Type | Capacity (MW) | Key Feature |
|---|---|---|---|---|---|---|
| Tehri | Bhagirathi | Uttarakhand | 260.5 m | Earth-rockfill | 2,400 (total) | Tallest in India, PSP, seismic debate |
| Bhakra | Sutlej | Himachal Pradesh | 226 m | Concrete gravity | 1,325 | Green Revolution backbone |
| Hirakud | Mahanadi | Odisha | 61 m | Composite | 307.5 | Longest dam system, flood control |
| Sardar Sarovar | Narmada | Gujarat | 163 m | Concrete gravity | 1,450 | Narmada dispute, Gujarat irrigation |
| Idukki | Periyar | Kerala | 169 m | Arch dam | 780 | Tallest arch dam in Asia |
Related: Krishnarajasagara Dam
Tehri and the Ganga System
Because Tehri sits on the Bhagirathi — one of the two headstreams that form the Ganga at Devprayag — it occupies a unique position in India's hydrological and cultural landscape. The Ganga is not just a river system; it carries constitutional recognition under the National Mission for Clean Ganga (Namami Gange) programme. Any question on upper Ganga basin management, Himalayan ecology, or Ganga rejuvenation can reference Tehri as a critical upstream intervention.
Frequently Asked Questions
On which river is Tehri Dam built?
Tehri Dam is built on the Bhagirathi River at its confluence with the Bhilangna River in Tehri Garhwal district, Uttarakhand. The Bhagirathi is one of the two headstreams of the Ganga, originating from the Gaumukh glacier at Gangotri.
What is the height of Tehri Dam?
Tehri Dam stands at 260.5 metres (855 feet), making it the tallest dam in India and one of the tallest earth-and-rockfill dams in the world. It surpasses Bhakra Dam (226 m), which is the tallest concrete gravity dam in India.
Why is Tehri Dam controversial?
Tehri Dam displaced approximately 100,000 people and submerged the old Tehri town. It sits in Seismic Zone V, raising earthquake-risk concerns. Sunderlal Bahuguna led a decades-long protest movement against the project, arguing that Himalayan communities bore disproportionate costs for benefits enjoyed by distant cities.
What is the Tehri Pumped Storage Project?
The Tehri PSP is a 1,000 MW pumped storage hydropower plant being commissioned as Stage II of the Tehri complex by THDC India Limited. It pumps water from the downstream Koteshwar reservoir to Tehri Lake during off-peak hours and generates electricity during peak demand, functioning as grid-scale energy storage.
Why is Tehri Dam important for UPSC?
Tehri combines Himalayan river geography, hydropower and energy transition, seismic risk, development-induced displacement, and Ganga basin management into a single multidimensional topic. It appears in Prelims through height-ranking and river-matching questions, and in Mains across GS Paper I (geography), GS Paper III (environment, disaster management), and GS Paper IV (ethical dimensions of displacement).
Tell Google you want more of this.
Add Anantam IAS as a preferred sourceOne tap, and this site shows up more often in your own Top Stories, AI Overviews and AI Mode. Remove it any time.
