The Mysterious Moawhango – A River on the Rise

Nick is inspired by a river reborn.

These days, when we hear so many doom and gloom stories about the decline of rivers and fisheries, it’s nice to hear of a situation where things are actually improving. The Moawhango is an example of this, a river that’s in better shape now than it was ten years ago.

Dammed to death…

When I first moved to the central North Island of New Zealand, this Rangitikei tributary was not high on my list of waters to visit…

In 1979, the river was dammed to form Lake Moawhango. This was to divert the river’s headwaters into the Tongariro Power Scheme, leaving flow below the dam coming from only a few minor tributaries. The dam itself, and the upper Moawhango in the Kaimanawa Ranges (reputed to contain brook trout), was and still is off limits to anglers, being contained in the Waiouru Military Camp training area. My 1995 edition of John Kent’s ‘North Island Trout Fishing Guide’ more than hinted at problems with the fishery, stating that “Unfortunately, this once excellent river has suffered greatly from hydro development and reduced river flow”.

After 2002, when Genesis Energy Ltd was granted consent to divert the water, the situation below the dam became so dire that Wellington Fish and Game Council assessed that the catchable populations of both brown and rainbow trout had disappeared from the dam down to the confluence with the Rangitikei.

A river on the rise

While anglers and other recreational users lamented the loss of the river, it took more than that to help it recover. Many farmers (often the brunt of blame for environmental degradation) were dismayed by the sick state of the river. Local Māori Iwi too had lost a treasured resource. Pressure from these stakeholders led Genesis to agree to minimum environmental flows from the dam, including a number of flushing flows during summer. These simulate natural flooding events, scouring algal build-ups and boosting the overall ecology of the river.

These days, the Moawhango is once again an attractive-looking river, although it wasn’t that way for decades.

While the Moawhango may never return to the fishery it was before the dam, since 2013, Fish and Game drift dive surveys have shown a very significant recovery of both browns and rainbows in the river.

Environmental flows are only part of the restoration of the Moawhango. Farmers too, through the Rangitikei Rivers Catchment Collective (RRCC), have made substantial changes to land management methods and aquatic monitoring practices. There has also been government involvement at a regional level, removing willows from heavily-choked areas of river.

A group effort

I recently attended the Annual Rangitikei and Moawhango Consultative Community Meeting, held by Genesis Energy, where presentations were made about all these issues. I found it very encouraging to see industry, farmers, fisheries management and local government all showing genuine care and taking real action to improve the state of the river. As an angler, it’s easy to focus on the quality of the fishing, but as a human being, it’s beyond casting a fly rod. It’s heart-warming simply to see a clean, flowing river compared to a slimy drain.

At the meeting, Genesis showed a commitment that went beyond a mere PR exercise. There was significant supporting science presented around the flow regimes, and there is ongoing statistical monitoring and reporting of aquatic invertebrate populations, and algal and weed observations. This included welcoming an independent audit of all aspects of managing the flows and monitoring river health.

Genesis showed a very open communication policy, with environmental officers inviting contact from anglers and other river users with reports or concerns regarding the condition of the river.

Landowner Mark Chrystall, from the Upper Moawhango River Catchment Group of the RRCC, gave an amazing talk on work being done by farmers. This included fencing off streams from stock, re-establishment of wetlands, and involving school groups in tree planting. Monitoring of the river included water quality testing and additional macroinvertebrate sampling. It was impressive to note that, despite being voluntary, there had been 100% sign-up to the program by all landowners in the catchment.

Horizons Regional Council reported on willow removal, which was performed by a ‘tiger team’ in kayaks to get to the many parts of the river inaccessible on foot. (More about accessibility later!) The initial focus was to carefully poison the willows above the water line.

And finally, the meeting included a Fish & Game presentation on drift dives performed on both the main Rangitikei River and the Moawhango. While there have been minor fluctuations in trout populations over recent years, both rivers were showing healthy numbers of good-sized brown and rainbows. Which brings me to…

The fishery

Most references to present-day Moawhango fishing usually mention how difficult the fishery is. However, this relates more to getting in, out and sometimes across the river, rather than the technical nature of the fishing.

Fishing access

Much of the Moawhango lies in deep gorges, bordered by cliffs. This includes several of the public bridge crossings. I can attest that there are white knuckle climbs in and out of some access points. When a Kiwi like my local mate Angus says something like, “It’s a bit of a climb out”, it translates in Australian as “Prepare to put your life in your hands!”

Beautiful water and spotting, but the terrain can require some planning around!

Easier access is often across private property. Access is rarely refused, but permission should always be sought. One landowner told me she always gave permission, on two grounds. Firstly, that having fought so hard to get the fish back in the river, she wanted to see them all returned if caught. And secondly, that anglers advised her when they were leaving, so she knew that they had made it out safely.

The other safety issue relates to the Genesis flushing flows. These are conducted five times a year. The flushes result in a surge of water that lasts for several hours, and obviously doesn’t coincide with rain events. This means unsuspecting anglers could be left trapped or even swept downstream without warning, on a fine, sunny day. Thankfully, these flushing flows are advertised in advance, and republished on the Fish & Game Website. There are also general warning signs near all public access points.


Safety issues aside, the Moawhango is a really pleasant fishery. Effectively a managed-flow tailwater, it has a mix of pools, riffles, runs and glides, which all contain fish. There is a relatively even mix of browns and rainbows, and each species is usually where you would expect to find them. Rainbows dominate in the faster water. They can sometimes be spotted in advance, but often a carefully fished weighted nymph, presented blind through likely areas, will tease out a solid rainbow.

Good rainbows can be fished up ‘blind’ in the faster water.

The browns are normally more of a sight fishing proposition. A slow, stealthy approach will reveal browns cruising in the pools, on station hard up against a bank, or in the softer water adjacent to heavier flows. Of course, the places browns prefer often put them where drag is an issue, so good presentations are needed to fool the Moawhango brown trout.

Browns are best spotted first, before making a careful drag-free presentation.

The river has a healthy macroinvertebrate population with mayfly, caddis and stonefly all being present. It’s possible to find daytime risers, and there is regularly a productive evening rise.

Tailwater factors

The artificially managed flows in the Moawhango influence the fishery in several ways. Firstly, the river is less susceptible to flooding, making it a viable option when other rivers in the area are blown out. This includes early and late season when most streams are very much at the mercy of the weather. While not a guarantee (a recent visit with my friend Simon, from Australia, was wiped out by heavy local rainfall low down in the catchment), the river offers a much better chance of fishable water after big rain events than most of its neighbours.

Secondly, because of the lower than natural flows, it pays to be slow and stealthy when fishing. The trout can be in skinny water and will spook readily if you wade heavily or move carelessly on the bank. The high bankside cliffs offer a plus and a minus here. On the plus side, they provide backdrop cover to reduce the risk of spooking fish with your silhouette. On the minus side though, is the need to factor in the high banks when you cast. Moving as slow as a heron and getting as close to the fish as you dare is often the answer.

Good cover, bad backcast!

The third issue relates to the flushing flows, and why they are needed. Between these flows, particularly in summer, algae can start to build up on the streambed. This can make the fishing less pleasant, with fouling of flies, slippery wading, and sluggish fish. Conversely, a week after a flushing flow can stimulate some really good conditions, with the river and fish reenergised. With the flows advertised in advance, you can at least tentatively book a Moawhango session into your angling calendar some time ahead.

So there you have the managed Moawhango. While it might have been an even better fishery without the existence of the dam, care and action from all stakeholders have made it a quality fishery, and certainly much better than it was 10 or 20 years ago. It has certainly been an unexpected addition to my list of regular local locations. In these times when all we seem to hear is bad news, I find it quite an inspirational story.