If you want to catch up with long-lost paddling friends or look for an elusive paddling girlfriend or easily find a new boyfriend, just turn up at one of the spring or autumn Mangahao releases when the river becomes the busiest in the country. It's an excellent place for hearing the latest gossip, but removes any feeling of wilderness this run would have without all the people.
The Mangahao is dammed twice in the Tararua Ranges and its flow is diverted to Arapeti Stream, then west to Mangaore Stream. The Whitewater Park below the Mangahao Power Station makes use of this water, but use of the main Mangahao River is limited to when King Country Energy releases water twice a year by agreement, or when heavy rain forces them to spill water.
Having survived the very tight and winding road to the put-in, find a park and catch up with old friends. If you want you can even charter a helicopter from the take out thus avoiding the heinous shuttle. Escape to the river, which starts as a single channel in a deep bush-lined valley. A few kilometres down is the first gorge with a couple of rapids in the easy class IV range. The crux rapid in the first gorge is a series of drops through a narrow section culminating in a final rapid with some fun hydraulics. A large tree wedged at the bottom provides the objective danger in the rapid. There are some good play spots in this section, but you'll have to join the queue.
Once clear of this gorge there is a long stretch of relaxing and enjoyable class II-III water with fabulous scenery. A few harder class III+ rapids shake you out of your reverie, including boulder gardens requiring active manoeuvering to stay out of trouble. Two or three may make it to IV-, depending on the flow.
Gradually these rapids give way to easier water and the hills lay back into pastoral land. The river becomes shallow, braided class I and II. The take out arrives just as you decide you really didn't want a flat water training session for the day. Often there are stalls set up selling hot dogs, beer and other essential post-river delights. One of the trickiest parts of this run is ensuring your shuttle driver knows how to get from the put in to the take out.
To get to the put-in: go to the small town of Shannon on SH7 south of Palmerston North. Follow the signs to Mangahao Power Station. Drive past the station and Whitewater Park up the gravel road which climbs over a saddle. It descends slightly to Tokomaru No 3 Reservoir, skirts this and climbs again twisting and turning like a slippery eel. Eleven kilometres from the power station you arrive at Mangahao Reservoir No 2 and the put-in.
To get to the take-out: head back to Palmerston North on SH7. Find any signs which point to Aokautere or Pahiatua Track. Follow this windy road over the Tawarua Ranges. As the road flattens onto the lowlands near Makomako, look for a junction and right turn to Marima. Once at Marima follow signs to Kopikopiko via Kopikopiko Road. This road turns to gravel a couple of kilometres out of Marima and stays this way to the bridge. The take-out is in a paddock on the river left just upstream of the bridge. Good luck.