Introduction: Timeframe

The Tehri Dam, located on the Bhagirathi River in the Indian state of Uttarakhand, is one of the tallest dams in the world and the largest in India. It serves multiple purposes, including hydroelectric power generation, irrigation, and municipal water supply. The dam has been a subject of significant controversy due to its environmental and social impacts.

Background and Construction

Initial Proposal:

• The concept of the Tehri Dam was first proposed in the 1950s to harness the hydropower potential of the Bhagirathi River.
• The project was initially envisioned as part of India's efforts to boost its hydroelectric power capacity and improve water management in the region.

Project Approval and Financing:

• The detailed project report was completed in 1972, and construction began in 1978.
• The project faced numerous delays due to technical challenges, funding issues, and strong opposition from environmentalists and local residents.
• The project received financial and technical support from the Soviet Union initially and later from various international agencies, including the World Bank.

Construction Phases:

• Construction of the main dam structure began in 1994 after years of delays.
• The dam's construction involved complex engineering feats, including the creation of a 260.5-meter-high rock and earth-fill embankment.
• The main components of the project include the dam itself, a powerhouse, and a series of tunnels and spillways.

Completion:

• The first phase of the project, which included the completion of the dam and the commissioning of the first hydroelectric units, was completed in 2006.
• The full capacity of the hydroelectric plant was reached in 2012, with a total installed capacity of 1,000 MW.

Features and Specifications

Dam Structure:

• Type: Earth and rock-fill dam.
• Height: 260.5 meters (855 feet), making it one of the tallest dams in the world.
• Length: 575 meters (1,886 feet).
• Reservoir Capacity: The reservoir, known as Tehri Lake, has a capacity of 4.0 cubic kilometers (3,200,000 acre-feet).

Power Generation:

• Installed Capacity: 1,000 MW from four 250 MW Francis turbines.
• The power generated is distributed to several states, including Uttar Pradesh, Uttarakhand, Punjab, Delhi, Haryana, Jammu & Kashmir, Chandigarh, Rajasthan, and Himachal Pradesh.

Irrigation and Water Supply:

• Irrigation: The dam provides irrigation to an area of 270,000 hectares (670,000 acres) in the downstream states.
• Drinking Water: It supplies 270 million gallons of drinking water daily to the industrialized areas of Delhi, Uttarakhand, and Uttar Pradesh.

Controversies and Environmental Impact

Environmental Concerns:

• Ecological Impact: The creation of the reservoir led to the submergence of forests, agricultural land, and habitat for various species, causing significant ecological disruption.
• Seismic Risks: The dam is located in a seismically active region, raising concerns about its safety in the event of an earthquake. Critics argue that the area’s geology could pose risks to the structure’s integrity.

Social Impact:

• Displacement: Approximately 100,000 people from 125 villages were displaced due to the creation of the reservoir. Resettlement and rehabilitation of these people have been a major issue, with many complaints about inadequate compensation and poor living conditions in the resettlement areas.
• Cultural Impact: The submergence of towns, including the historic town of Tehri, resulted in the loss of cultural heritage and community structures.

Opposition and Protests:

• The project faced strong opposition from various environmental activists, including prominent figures like Sunderlal Bahuguna, who led the "Save Tehri" campaign.
• Protests highlighted the environmental and social costs of the project, advocating for alternative, less destructive approaches to water and energy management.

Benefits and Current Status

Economic Benefits:

• The Tehri Dam has significantly contributed to the regional economy through improved irrigation, which boosts agricultural productivity, and reliable water supply, which supports industrial activities.
• The hydroelectric power generated by the dam helps meet the energy needs of several states, reducing reliance on fossil fuels and contributing to energy security.

Current Operations:

• The dam is operated by the Tehri Hydro Development Corporation (THDC) India Ltd., a joint venture between the Government of India and the Government of Uttarakhand.
• Ongoing monitoring and maintenance are conducted to ensure the dam's safety and operational efficiency, particularly in light of the seismic concerns.

Future Developments:

• Plans for additional projects, including the Tehri Pumped Storage Plant (PSP), which will further enhance the dam's power generation capacity and provide peaking power to the grid.

The Tehri Dam is a monumental engineering achievement with significant contributions to hydroelectric power generation, irrigation, and water supply in India. However, it also exemplifies the complex interplay between development and environmental sustainability, highlighting the need for careful consideration of ecological and social impacts in large infrastructure projects. The lessons learned from the Tehri Dam experience continue to inform policy and practices in dam construction and water resource management globally.