Tama Koshi (Tamakoshi)

The Tama Koshi begins across the Tibet border, where the Rongshar Chu and the Lapche stream drain the high country around Gaurishankar and the Rolwaling Himal. It enters Nepal at Lamabagar in Dolakha and runs about 92 km south through Dolakha and Ramechhap districts to meet the Sun Koshi near Khurkot.

At Lamabagar the river drops through one of the steepest usable heads in the country — 822 m — which the 456 MW Upper Tamakoshi project converts into Nepal's largest power station. Inaugurated on 5 July 2021 and designed for a 66 m³/s flow through six Pelton turbines, it was financed entirely within Nepal: the Nepal Electricity Authority, Nepal Telecom, the Citizen Investment Trust and Rastriya Beema Sansthan took the major stakes, with shares reserved for the general public and for the people of Dolakha — a point of national pride.

The valley was a hydropower pioneer well before that. The 60 MW Khimti plant on the Khimti Khola tributary, built between 1996 and 2000, was one of Nepal's first large independent power projects, and run-of-river cascades continue to stack up along the corridor.

The upper valley lies inside the Gaurishankar Conservation Area — 2,179 km² declared in 2010 across Dolakha, Ramechhap and Sindhupalchok — whose forests and high valleys shelter snow leopards and red pandas above the river's gorges.