The 1200 MW Punatsangchhu-I Hydroelectric Project is envisaged to generate 5700 million units in an average year

Confluence of Phochhu and Mochhu rivers near Punakha Dzong

Punatsangchhu-I Hydroelectric Project Authority (PHPA-I) is an autonomous body set up for implementation of the 1,200MW Punatsangchhu-I Hydroelectric Project (PHEP-I), the mutually beneficial Indo-Bhutan Friendship Project. The project’s implementation started on November 11, 2008. Originating at an altitude of ±7,000 masl in Gasa Dzongkhag (District) of Bhutan and fed by snow/glacial lakes from the Great Himalayan Range, the rivers Phochhu and Mochhu join at an altitude of ± 1212.2m masl at the iconic Punakha Dzong (Fortress) to form the Punatsangchhu river which then flows southerly to enter the Indian plains as Sankosh. This run-of-the-river Project located by the  7-21 km stretch of Wangdue-Tsirang National Highway in Wangduephodrang Dzongkhag in Western Bhutan is the first project under the 10,000MW Hydropower Development Initiative undertaken by the Royal Government of Bhutan (RGoB) and the Government of India (GoI). Designed to generate 5,670 million units of electricity in an average year, the Project utilizes 357 m of head available in about 11 km length of Punatsangchhu river. The Dam site is about 7 km downstream of Wangdue Bridge and all other project components are located on the left bank of the river between 7 km and 21 km downstream of the  Wangdue Bridge


The Main Civil Works of the project has been divided into three packages: MC-1, MC-2, and MC-3.

Construction of a Diversion Tunnel, Dam, Intakes, and Desilting Chambers; including associated Hydro-Mechanical (HM) works was awarded to M/S Larsen & Toubro.

Construction of Headrace Tunnel (HRT) from Adit-I & Adit-II. This was awarded to M/S Gammon India Ltd and stands Completed

Construction of Headrace Tunnel (from Surge Shaft End) , Surge Shaft, Butterfly Valve Chamber, Pressure Shafts, Power House, and Tailrace Tunnel works was awarded to M/S Hindustan Construction Company


  • MC-1 (including Hydro-Mechanical works) 69.87% 69.87%
  • MC-2 (including Hydro-Mechanical works) 100% 100%
  • MC-3 (including Hydro-Mechanical works) 99.69% 99.69%
  • Electro-Mechanical works 98.31% 98.31%
  • Transmission Line 99.94% 99.94%


Over all Progress


The last assembly of the Generator Rotor weighing 315,000Kg for Generating Unit-5 has been completed and lowered in the Generator barrel on December 29, 2021, and thereby assembly and lowering of all the Stators (266,000kg) and Rotors for 6 nos. of Generating Units stands completed. The 3 nos. of Generating units had been boxed up and the same is in progress for other Units.