Mangahao (III+ / IV)

This has always been regarded as the premier Tararua river for kayaking but it is dammed.  On the rare release days it’s pretty popular and has some heavy Class IV features unsuitable for Packrafts.  It was once a popular tubing river in low flows but residual flows are insufficient for it to receive much paddler use.  It has a tight gorge similar to the Hutt or Otaki and then a final gentler section which requires more water.  So the challenge is to find a suitable weather window i.e. low enough for the crux rapid to be passable but not so low that the last 5-10 km becomes a chore.

Like all hydro rivers, it could be subject to spills at any time that drastically change the flow (and river grade). As of 2020 there are no programmed release dates because the spill diversion is programmed for repair. WWNZ are liaising with the operators on this.

The Shuttle

It is a very long shuttle of over two hours and there is no walk in float out option.  So it’s best to enrol a shuttle bunny.

To get to the put-in:

Turn off SH7 just north of Shannon and enjoy the lovely road as far as the Mangahao Slalom site.  Now the road gets hellishly windy and narrow.  Eventually, you will reach the massive concrete arch dam that stores water from the next catchment.  Continue on around the lake and over into the next valley.  At the bottom of the hill is the lower of two dams on the Mangahao. Twice a year by agreement King Country Energy allow a release for kayakers.  It’s best to avoid these times as the crux rapids are not packraft friendly at these flows. Head down the track ten minutes to the river and inflate your packraft.

To get to the take-out:

Head north on SH7 and right over the Pahiatua Track. Once over the northern Tararua foothills, the road flattens. Near Makomako turn 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.

On the River

The natural flow of the river would be quite large and so the meagre residual flow occupies a wide bed.  Enjoy the bush lined valley and chilled paddling because a few kilometres ahead it gets tight and very gnarly.

In the gorge proper, there are 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. Scout and portage where necessary.  At low flows, these rapids can still be hazardous and or boney.  Portage may not be viable.  As with all Tararua rivers, check in with someone who has run it recently and expect unexpected logs.

Once clear of this tight gorge it’s a return to boulder gardens and there is a long stretch of class II-III water with fabulous scenery. A few of the rapids will be class III+ or even IV- at higher flows.  There’s a gradual transition to Class II and then farmland appears and the river becomes shallow, braided Class I and II.  The take-out is at the bridge.  Kayakers can take 8 hours so consider overnighting at the put-in or after the gorge eases.  Tubing trips were usually overnighters.

Gauge

This trip has been written up as a placeholder. It is based on tubing memories, youtube videos, guide books and conversations. It does not appear to have been packrafted yet. The optimum flow band is a matter for ongoing resolution.  Kayakers recommend 15m3 or more.  1980s /90s tubing in late autumn would have involved flows of perhaps 5m3.  This suggests 5 -10m3 would be ideal.  The wider downstream reaches will be pretty shallow at these flows.  Help find the sweet spot by commenting if you do the trip.

The Gauge is Mangahao at Balance and shows the sorry state of the flow year round. Thanks clean green hydro!

https://envirodata.horizons.govt.nz/?siteName=Mangahao%20at%20Ballance&collectionName=Flow


View Larger Topographic Map

Theres is limited video available but these show the Crux rapids on release days.

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