Punatsangchhu-I Hydroelectric Project Authority (PHPA-I) is an autonomous body set up for implementation of 1,200 MW Punatsangchhu-I Hydroelectric Project (PHEP-I), the mutually beneficial Indo-Bhutan friendship Project. The project implementation started on November 11, 2008.
Rising 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 ±1,200 masl at Punakha to form the Punatsangchhu river which flows southerly to enter the Indian plains.
The (1,200 MW) run-of-the-river PHEP-I in Wangduephodrang Dzongkhag in Western Bhutan is the first project of the 10,000 MW Hydro-power Development Initiative taken by the Royal Government of Bhutan (RGoB) and the Government of India (GoI) to be achieved by 2020. Designed to generate 5,670 million units of electricity in an average year, the Project utilizes 357 m head available in about 11 km length of Punatsangchhu. 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 17 km downstream of the Wangdue Bridge.