Its source is in the Ruahine Range and its outflow is into the larger Rangitīkei River, which it meets close to Mangaweka.

[2] Like other parts of the Rangitīkei River system, the Kawhātau has been incised into the soft Quaternary, 3.5 to 1.7 million year old marine mudstones and sandstones, as the land has risen since the last ice age.

[6] Māori skeletons and moa bones were discovered near the river when the bush was being burnt.

At that time the only access was by a cage suspended on a 380 ft (120 m) wire rope across the Rangitīkei from Mangaweka (then called Three Log Whare).

[22][23] Plants found in the valley in 2000 included Mazus novaezeelandiae (dwarf musk), Anemanthele lessoniana (gossamer grass), Trisetum drucei (tufted grass), Scandia rosifolia, Azorella hookeri, Rubus squarrosus (bush lawyer), Trisetum lepidum (3-bristled grass), Uncinia leptostachya (hook-sedge), Asplenium flabellifolium (necklace fern), Korthalsella lindsayi (leafless mistletoe), Myoporum laetum (Ngaio), Olearia paniculata (Akiraho), Lastreopsis velutina (shieldfern) and Schoenus pauciflorus(Sedge tussock).