The tributary measures 50 km (31 mi) in length, originating in the hills of the Horton Plains National Park, before passing through the Castlereigh Reservoir.

The river is heavily used for hydroelectric power generation.

[1][2] The following table lists the features along the Kehelgamu Oya, from its origins further upstream.

Some dams hold back water, and transfer a percentage of it to hydroelectric power stations located further downstream, via tunnels.

This article related to a river in Sri Lanka is a stub.