The Karcham Wangtoo Hydroelectric Plant is a 1,091 megawatts (1,463,000 hp)[2] run-of-the-river hydroelectric power station on the Sutlej River in Kinnaur district of Himachal Pradesh state of India.

[3] The dam and power station are located between the villages of Karcham and Wangtoo where the plant also gains its name.

[5] The 98 m (322 ft) tall dam at Karcham (31°30′00.26″N 78°10′39.54″E / 31.5000722°N 78.1776500°E / 31.5000722; 78.1776500 (Karcham Dam)) diverts a substantial portion of the Sutlej into a 10.48 m (34.4 ft) diameter and 17.2 km (10.7 mi) long headrace tunnel to the underground power station downstream at Wangtoo.

At the station, the water powers four 250 MW Francis turbine-generators before it is sent back into the Sutlej via a 1.2 km (0.75 mi) long tailrace tunnel.

The difference in elevation between the dam and the power station affords a gross hydraulic head of 298 m (978 ft).