The project’s first two 1-gigawatt turbines will go into formal operation after a three-day trial, CCTV said.

The project will eventually consist of 16 such units, making its total generation capacity second only to the Three Gorges Dam once it is fully completed in July next year.

Baihetan was built by the China Three Gorges Corporation and is located on the border between the southwestern provinces of Yunnan and Sichuan.

It is part of a cascade of dams on the Jinsha River, which is the upstream section of the Yangtze.

Though the Three Gorges Corporation said it was one of China’s biggest and most challenging engineering projects, with a dam height of 289m, it has taken only four years to build.

The project is part of a national scheme to generate electricity and deliver it to high energy-consuming regions on the eastern coast, and is also designed to strengthen control over water flows during the heavy summer flood season.

But the large-scale damming of the Yangtze and its tributaries has been criticised by environmental groups, who say the over-engineering of the river has destroyed major habitats and damaged natural flood plains.