Its source is numerous streams draining the slopes of the Te Waka Range in the Rukumoana Forest area.

For most of its course it is deeply incised[1] in the tephra, ignimbrite and lapilli volcanic rocks, which are a bit over 30,000 years old.

The deep valleys are partly due to the soft rocks and partly to the rapid rise of the Mohaka Fault, at over 3 mm (0.12 in) a year.

[3][4][5] The river suffers from pollution by nitrogen and phosphorus.

This article about a river in the Hawke's Bay Region is a stub.