The Tehri Dam Explained

The Tehri Dam is a roughly 260 m high earth-and-rock-fill dam on the Bhagirathi River in the Tehri Garhwal district of Uttarakhand, and it is the tallest dam in India and one of the tallest dams in the world. It is operated as part of the Tehri Hydro Development Corporation India Limited (THDC India Ltd) complex, which generates hydropower, supplies drinking water to Delhi and parts of Uttar Pradesh, and supports irrigation.

The Tehri Dam sits close to the confluence of the Bhagirathi and Bhilangana rivers, in the Himalayan foothills of the Garhwal region. Its construction took several decades, submerged the old Tehri town, and drew a long-running public debate about displacement, the seismic safety of building a very large dam in an active mountain zone, and the benefits of hydropower and water supply. This explainer sets out the facts and the main positions in the debate in a neutral way. Figures are rounded and widely reported, and they should be treated as approximate.

Quick Facts

Key Takeaways

• The Tehri Dam is an earth-and-rock-fill dam about 260 m high on the Bhagirathi River in Uttarakhand, and it is the tallest dam in India.
• The Tehri Dam complex includes the 1,000 MW Tehri Stage I plant, the downstream Koteshwar plant and the Tehri Pumped Storage Plant, all operated by THDC India Ltd.
• The Tehri Dam reservoir supplies drinking water to Delhi and parts of Uttar Pradesh and supports irrigation in the Gangetic plain.
• The Tehri Dam submerged the old Tehri town, and the state built New Tehri on higher ground to rehabilitate residents.
• The Tehri Dam stands in a high seismic zone, and its design for strong earthquakes has been a central point of public debate.
• The Tehri Dam is a multipurpose project whose benefits in power and water are weighed against displacement and environmental concerns.

What is the Tehri Dam?

The Tehri Dam is a multipurpose river valley project built to generate electricity, store water for irrigation and supply drinking water, and it is the centrepiece of the Tehri Hydro Power Complex in Uttarakhand. The dam wall itself is an earth-and-rock-fill embankment, a type made from compacted soil and rock rather than concrete.

The project is a complex of several linked structures. The main Tehri Dam holds back the Bhagirathi, a headstream of the Ganga, and creates a large reservoir that extends upriver and into the Bhilangana valley. Downstream, the Koteshwar Dam acts as a balancing reservoir, and the Tehri Pumped Storage Plant uses the two reservoirs to store energy by moving water between them.

The dam is often listed among the tallest dams in the world, and in India it is the tallest. Its height and size make it a landmark of Himalayan engineering.

Where is the Tehri Dam and why was this site chosen?

The Tehri Dam is located on the Bhagirathi River just below its confluence with the Bhilangana, in Tehri Garhwal district of Uttarakhand, roughly 80 km from Rishikesh by road. The site lies in a narrow Himalayan gorge that suits a high dam and a deep reservoir.

Engineers favoured the location for several reasons.

• Narrow gorge: a narrow valley reduces the length of wall needed to hold back a large volume of water.
• Two rivers meet here: the joining of the Bhagirathi and the Bhilangana provides a large and reliable inflow fed by snowmelt and monsoon rain.
• Large head of water: the steep mountain drop gives a high head, which is valuable for hydropower.
• Proximity to the plains: storage high in the Himalayas can regulate flows for the Ganga basin and supply water to Delhi and western Uttar Pradesh.

The area also sits in a seismically active belt, which led to extensive geological investigation and a design conservative enough to meet very strong ground motion.

How tall is the Tehri Dam and what type of dam is it?

The Tehri Dam is about 260 m tall, which makes it the tallest dam in India, and it is an earth-and-rock-fill embankment dam with a central clay core. A fill dam relies on its sheer mass and gently sloping sides to resist the pressure of the water.

Building a fill dam rather than a concrete one suited the site for practical reasons. Earth and rock fill can flex slightly during an earthquake without cracking suddenly, and the materials can be obtained near the site. The clay core in the middle stops water from seeping through, while the outer shells of rock and gravel give the structure its strength and stability.

The reported height varies slightly between sources depending on whether it is measured from the foundation or the river bed. For that reason, 260 m is best read as a rounded, commonly quoted figure.

How does the Tehri Dam generate hydropower?

The Tehri Dam generates hydropower by releasing water from the high reservoir through tunnels and penstocks to turbines in underground powerhouses, which drive generators and produce electricity. The height of the water above the turbines gives it great energy, so a given flow produces a large amount of power.

The Tehri complex is organised in stages and units.

• Tehri Stage I: four units of 250 MW each, giving 1,000 MW, commissioned in the mid-2000s with the first power around 2006.
• Koteshwar Hydro Electric Project: a downstream dam and powerhouse of about 400 MW that regulates the water released from Tehri.
• Tehri Pumped Storage Plant (PSP): a plant of about 1,000 MW that is part of Tehri Stage II and was brought into service in stages in the early 2020s.

The electricity is fed into the northern grid and is shared among several states, including Uttar Pradesh and others in the region. Because the plant can start quickly and adjust its output, it is useful for meeting peak demand.

What is the Tehri Pumped Storage Plant?

The Tehri Pumped Storage Plant is a hydropower facility of about 1,000 MW that stores energy by pumping water from the lower Koteshwar reservoir up to the Tehri reservoir when electricity is cheap and generating power from the stored water when demand is high. In effect, it works like a very large rechargeable battery for the grid.

The process runs in a daily cycle. At night or when solar and wind output is high, spare electricity drives reversible pump-turbines that lift water uphill. During the evening peak or when other sources fall short, the water is released back down through the same machines, which then work as generators. This improves grid stability and helps to integrate renewable energy.

Pumped storage is considered important for India’s plan to add large amounts of solar and wind power, because those sources vary through the day. The Tehri PSP is one of the larger pumped storage plants built in the country.

How does the Tehri Dam supply water for drinking and irrigation?

The Tehri Dam supplies water by storing monsoon and snowmelt flow in its reservoir and releasing it in a controlled manner through the year, so that downstream cities and farms have a steadier supply. The reservoir holds roughly 2.6 billion cubic metres of water at gross storage.

The planned water benefits include the following.

• Drinking water for Delhi: a treated supply is sent to the national capital through a pipeline and canal system, serving a very large urban population.
• Drinking water for Uttar Pradesh: parts of the state, including towns in western Uttar Pradesh, receive supply.
• Irrigation: the stored water supports irrigation over a large area of the Gangetic plain, supplementing existing canal systems.
• Flow regulation: releases can be timed to improve the dry-season flow of the Ganga and its tributaries.

The exact quantities of water allocated to Delhi, Uttar Pradesh and irrigation are set in inter-state arrangements and may differ in practice from original design figures, so they should be checked with the operator or relevant authorities.

What happened to Old Tehri town and its people?

Old Tehri town was submerged by the Tehri reservoir, and its residents were relocated, with New Tehri built on higher ground as the replacement town. Old Tehri had been the capital of the Tehri Garhwal princely state, founded in the early 19th century at the confluence of the Bhagirathi and Bhilangana, and it was a place of considerable history and local identity.

The project affected many villages, some fully submerged and others partly affected by the rising water or the loss of connecting roads and farmland. Families were offered rehabilitation that generally included house plots, compensation and, in some cases, agricultural land in other districts.

Rehabilitation and its assessment

Supporters of the project point to the new town, with housing, schools and administrative buildings, and to the compensation provided. Critics and social researchers have raised concerns about the adequacy and timing of compensation, the loss of farmland, the disruption of communities and the difficulty of re-establishing livelihoods. Both views are part of the record, and the experience is often studied as a case in resettlement policy.

New Tehri

New Tehri is a planned town on the hillside above the reservoir, and it serves as the district headquarters. The lake and the surrounding hills have also made the area a destination for tourism and water sports.

Is the Tehri Dam safe in a seismic zone?

The Tehri Dam is built in a high seismic zone and was designed to withstand very strong earthquakes, though its safety has been questioned by some experts and defended by others. The region falls in seismic zone IV of India’s earthquake zoning, and the Himalayan belt has seen major earthquakes in the past, including the 1991 Uttarkashi earthquake that occurred in the broader area.

The main points in the safety discussion are as follows.

• Design standard: the dam was designed to resist a very strong maximum credible earthquake, and expert committees reviewed the design.
• Fill-dam behaviour: supporters note that earth-and-rock-fill dams can deform without catastrophic failure under shaking.
• Concerns raised: some geologists and environmental groups argued that the seismic risk in the young and unstable Himalayas had not been fully addressed, and they raised the consequences of a failure for communities downstream such as Rishikesh and Haridwar.
• Monitoring: the dam is fitted with instruments that track settlement, seepage, pressure and ground motion.

Government agencies and the operator have maintained that the structure meets safety norms, while critics continue to call for caution in Himalayan dam building. Safety assessment is technical and continues through regular inspection and monitoring.

What is the debate over the environment and the Tehri project?

The debate over the Tehri project centres on whether its benefits in power, water and flood moderation justify its social and environmental costs. The project drew sustained opposition from the 1970s onward, with environmentalist Sundarlal Bahuguna among the best-known figures in the campaign against it, while the government and many local leaders defended it as vital for development.

Courts and expert committees examined many of these questions over the years, and the project went ahead with conditions and revisions. Many researchers now treat the Tehri Dam as a case study in balancing development needs and local impacts.

Who built and runs the Tehri Dam?

The Tehri Dam is built and run by THDC India Ltd, formerly the Tehri Hydro Development Corporation, a public-sector company under the Ministry of Power. THDC India was set up in 1988 to take over the project, and it later expanded into a wider hydropower and renewable energy developer. In recent years it has been placed under the ownership of the central public-sector power company NTPC.

The idea of damming the Bhagirathi near Tehri dates back to surveys in the 1950s and 1960s, with detailed planning in the 1970s. Construction began in the late 1970s and then proceeded slowly because of funding, technical reviews, protests and rehabilitation issues. The reservoir began filling in the mid-2000s, and the first generating units were commissioned around 2006.

Technical cooperation from abroad, including early support from the former Soviet Union, contributed to the planning and equipment in the earlier phases, and Indian engineers took over increasing responsibility over time.

What is the timeline of the Tehri project?

The timeline of the Tehri project covers more than four decades from early surveys to full operation of the pumped storage plant. The key stages are summarised below with approximate dates.

Dates differ slightly between sources, since individual units and tunnels were completed at different times.

Why does the Tehri Dam matter for India?

The Tehri Dam matters because it is a very large, multipurpose asset that supports electricity supply, drinking water for the capital region and flexibility for the grid in a country with rising demand. As India expands renewable energy, large pumped storage and reservoir hydropower are valued for their ability to respond quickly to changes in demand.

Its significance has several dimensions.

• Energy security: it adds firm, dispatchable power to the northern grid.
• Water security: it supports urban water supply for Delhi and part of Uttar Pradesh.
• Engineering capability: it shows India’s capacity to build very high dams in difficult terrain.
• Policy lessons: it has shaped later discussion on resettlement, environmental assessment and dam safety.

At the same time, climate change, glacial melt and landslide risk in the Himalayas make careful long-term monitoring and basin management important.

Bottom Line

The Tehri Dam is India’s tallest dam, an earth-and-rock-fill structure of about 260 m on the Bhagirathi in Uttarakhand, and the core of a hydropower and pumped storage complex run by THDC India Ltd. It supplies power, water for Delhi and Uttar Pradesh and irrigation, while the submergence of old Tehri and the seismic questions remain central to the public debate. Last reviewed: 17 October 2026.

Frequently Asked Questions

How tall is the Tehri Dam?

The Tehri Dam is about 260 m tall, which is roughly 855 feet, making it the tallest dam in India. It is also counted among the tallest dams in the world. Exact figures vary slightly depending on the reference point used for measurement.

On which river is the Tehri Dam built?

The Tehri Dam is built on the Bhagirathi River, a major headstream of the Ganga, in Tehri Garhwal district of Uttarakhand. It stands close to the confluence of the Bhagirathi and the Bhilangana. The reservoir it creates is known as Tehri Lake.

How much electricity does the Tehri Dam produce?

The Tehri Stage I plant has an installed capacity of 1,000 MW, and the complex also includes the Koteshwar plant of about 400 MW and the Tehri Pumped Storage Plant of about 1,000 MW. Actual generation varies with water availability, season and grid demand. The pumped storage plant mainly stores and returns energy rather than adding new water.

What happened to Old Tehri town after the dam was built?

Old Tehri town was submerged by the reservoir, and its residents were rehabilitated, mainly in the newly built town of New Tehri on higher ground. Many nearby villages were also affected. Supporters highlight the new town and compensation, while critics point to lost land, livelihoods and community ties.

Is the Tehri Dam safe from earthquakes?

The Tehri Dam was designed to withstand very strong earthquakes and is monitored with instruments, although the region lies in a high seismic zone and some experts have questioned the risks. Authorities state that the design meets required safety standards. The debate continues, and regular inspection is an ongoing part of dam safety.

Does the Tehri Dam supply water to Delhi?

Yes, the Tehri Dam supplies treated drinking water to Delhi and to parts of Uttar Pradesh, in addition to supporting irrigation. The reservoir stores monsoon and snowmelt flow and releases it in a regulated way. The exact quantities depend on inter-state arrangements and may change over time.

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