Kai Auahi Stream (also referred to as Kaiauai) is a whitewater run in the Taranaki region of New Zealand, associated with the upper Waiwhakaiho catchment. It is described as a grade 3 to 3+ read-and-run river, making it suitable for paddlers comfortable at that level. The stream is often considered when the upper Waiwhakaiho is running too high to be enjoyable, suggesting it handles elevated flows well and serves as a practical alternative in those conditions.

The put-in is accessed from Hill Road: just before the end of the road there is a 90-degree bend, and immediately before that bend a left-turn track follows a tailrace down to the river. The walk from the road to the water is approximately 200 metres through a gate. A useful gauge check before committing to the run is to assess the put-in visually — if it looks bony there, the rest of the river is likely to be too low. An additional indicator is the Alfred Road bridge take-out rapid: if there is a kayakable line down the rapid on river left at that bridge, the river is considered good to go. A reference data point noted from July 2019 is that the Mid Waiwhakaiho gauge was reading 50 cumecs and dropping when paddlers chose to put on for the Kaiauai.

As of a July 2019 report, the river was clean of hazards, with every rapid being read-and-run without portaging. At every island or river split encountered, paddlers went left. The take-out is at the Alfred Road bridge. The run is associated with a map covering the Mid and Upper Waiwhakaiho and Kai Auahi area.