The Taueru River has a catchment area of 498 km2 and a total main channel length of 69 km. The Taueru valley is well known for its limestone hills and the various caves that have formed from weathering of the limestone. The catchment contains a mix of soils but is primarily soft sedimentary sandstone, limestone and Siltstone. Land-use in the catchment is predominantly primary production activities (dairying, dry stock grazing, cropping, plantation forestry). There are a few scattered areas of native forest, especially in less accessible steep-sided gully areas – including isolated locations where remnant totara and kahikatea can be found.

The Whangaehu River has a catchment area of 145 km2. Its springs rise in the steep hill country near Ihuraua and it flows through a narrow winding channel for 32 kilometres to the Ruamāhanga River. The geology of the catchment changes between sandstones, limestones and siltstones. Land-use in the catchment is mostly primary production activities with a few scattered areas of native forest. The 1970s river management techniques of straightening the river led to significant erosion issues which were addressed through willow planting. Unfortunately, this has led to issues with flooding and sedimentation.