Budhi Gandaki River is a tributary of the Trishuli River. The Budhi Gandaki rises near Samagaun (Gorkha District) in the Himalayas north of Manaslu. It is fed by several glaciers. Main tributaries are: Tom Khola draining from the Tibetan Highlands; Shyar Khola, which drains the Ganesh Himal Range from north and flows through the Tsum Valley; Chuling Khola, draining Himalchuli and Baudha Mountains; and Akhu Khola, which drains the Ganesh Himal Range from south.
The Budhi Gandaki has a length of about 150 km. Its catchment area is 5,370 km².
A dam project with a power plant capacity of 600 MW is planned about 2 km above the estuary to the Trishuli River.