Subansiri Hydroelectric Power Plant, India’s largest of its kind

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The latest Sep 2023

In Nov 2022 it was announced that the Subansiri Hydroelectric Power Project would be partially complete and operational in 2023, however, no specifics were given.

Recently though, it emerged that a 250-MW unit of the power plant would be commissioned in December 2023 or January 2024. This was revealed by the Chairman and Managing Director of NHPC Rajeev Kumar Vishnoi during a meeting to review the progress of the Subansiri Lower Hydroelectric Project. The meeting was held in New Delhi and was chaired by Union Power and New & Renewable Energy Minister R K Singh.

During the meeting, it emerged that blocks of the dam concrete had achieved a top level of 210 meters.  37 meters of the Dam height was also raised with a concrete pouring of more than 2.5 lakhs cubic meters during the last 06 months from June 2023.

The river-facing wall of the Power House on the other hand had been raised up to a safe elevation of 116 meters and the Tail Race Channel had been completed for all Units. The Water Conductor System was 100% complete as of June 2023.


Subansiri Hydroelectric Power Project Overview 

Also called the Lower Subansiri Hydroelectric Power Project, the Subansiri Hydroelectric Power Project is a 2,000MW power plant located on the Subansiri River on the border of Arunachal Pradesh and Assam, India’s two north-eastern states.

The project is being developed by National Hydro Power Corporation (NHPC), the state-run power company. It was launched in 2005 and was initially scheduled to be completed by 2010. It however ran into delays due to protests from environmental activists over the dam’s potential environmental impact.

Financing of the project

The Subansiri Hydroelectric Power Project was originally estimated to cost around $1.16 billion according to 2002 price levels. These estimations were however revised to $1.97 billion at 2010 price levels following delays.

The cost of the project was met through 70% equity and 30% debt financing through a term loan. The Indian government allocated budgetary support for the project as part of its equity financing.

Subansiri Hydroelectric Power project timeline 


In May 2003, India launched plans to develop 50,000MW of hydropower. The Subansiri Hydroelectric Power Project was part of the program. In August of the same year, the government cleared to commence construction. The NHPC started the development of the power project.


In January 2004, the Engineering Construction & Contracts (ECC) division of Larsen & Toubro was awarded a $169 million contract for the civil and structural work related to water diversion, tunnelling, and the powerhouse.


In 2005, construction work on the power plant started after delays due to issues with the allotment of land.


The diversion of the river was completed in April 2007. Excavation works were also carried out in the same year.


In October 2008, the dam was subjected to a fresh round of design.


Construction at the dam came to a stop for another five months due to the monsoon season.


In November 2011, some progress was made on dam excavation and associated tunnelling works. In December 2011, another round of protests forced the construction of the project to halt again.


As of December 2012, 55% of the project was complete with the excavation of the dam and the powerhouse finished. Only the concreting work was remaining. The diversion tunnel of the river was also completed.

In addition, by December 2012, around 60% of the hydro-mechanical equipment and 95% of the electromechanical equipment for the project had been supplied.


In July 2019, the National Green Tribunal gave the project the go-ahead to proceed with construction.  In August 2019, the NHPC signed a memorandum of agreement (MoA) with the Assam Government and obtained approval for the project. Work on the project commenced in October of the same year.

Dec 2021

2000MW hydropower project to be commissioned in Subansiri, India

National Hydroelectric Power Corporation (NHPC) of India announced that the 2,000MW Subansiri hydropower project will finally be commissioned in March of 2022. The Subansiri hydropower project has been stalled for nearly eight years due to intense protests by many groups in Assam.

Construction work at the ambitious project at Gerukamukh along the Assam-Arunachal Pradesh border on the Subansiri River was abruptly stopped from December 2011 to October 2019 due to protests by locals and many groups fearing safety and the adverse impact on the downstream of the river.

Also Read: Construction of 120MW Lower Kopili hydropower project in India begins

The initial cost of the project was an estimated US$8.5 million and US$14.9 million had been allocated as of December 2010 for the construction of the dam. According to estimates done in January 2020, the cost of the mega project which was scheduled to be commissioned in December 2012, had escalated to around US$27 million.

Sanjiv Nandan Sahai, the Union power ministry’s secretary, Arunachal Pradesh chief secretary Naresh Kumar and the company’s chairman and managing director A K Singh visited the Subansiri Lower Hydro Electric project sites and inaugurated the restart of the powerhouse works, NHPC said in a statement.

This announcement of the commissioning of the dam has, however, not been faced without opposition. Activists in the region rocked the environment by shouting various slogans opposing the dam project and the governments at the Centre and in the State for supporting the contentious project taking a U-turn of their past stand.

They claim that the declaration has shown that the government has completely ignored the issue of securing the life and properties of the people living in the downstream area of River Subansiri and has hurt the sentiment of the anti-big dam activist organizations and the public who have been initiating extensive stirs for years opposing the controversial big river dam project.

Nov 2022

Subansiri Hydroelectric power project to be commissioned in 2023

The 2000 MW Subansiri Lower Hydroelectric project is expected to be commissioned in 2023. This is according to Arunachal Pradesh Chief Minister Pema Khandu. The latter made the revelation during the inauguration ceremony of the Donyi Polo airport near Itanagar. The ceremony took place recently.

The Arunachal Pradesh Chief Minister said that with the commissioning of the Subansiri project, the region will contribute significantly to India’s target of achieving a 5 trillion-dollar economy.

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