The Wairoa Viewpoint looks directly over the dam and southern end of the Wairoa Reservoir. The quickest way there is to drive down Otau Road and park near the closed gate. Then continue to walk along the road to the clearly marked Wairoa Loop Track entrance on the right. Follow the track up until you reach the junction with Wairoa Viewpoint. It takes a few minutes to walk to the viewpoint.
If you continue on the Wairoa Loop past the repeater station, you will see a second viewpoint over the reservoir, looking north.
Overall, allow about 90 minutes return for the first viewpoint.