Kehelgamu Oya
The Kehelgamu Oya is a major upstream tributary of the Kelani River. The tributary measures in length, originating from the hills of the Horton Plains National Park, before passing through the Castlereigh Reservoir. Kehelgamu Oya converges with the Maskeliya Oya at Kalugala, forming the long Kelani River. The river is heavily used for hydroelectric power generation.
Features on the river
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.| Type | Subject | Location |
| Water airport | Castlereigh Water Airport | |
| Dam | Castlereigh Dam | |
| Power station | Wimalasurendra Power Station | |
| Dam | Norton Dam | |
| Waterfall | Aberdeen Falls | |
| Dam | Kehelgamu Weir | |
| Kelani River |