Martin Hill

Opanuku: from source to sea

Often ignored, frequently degraded, suburban streams are the Cinderellas of freshwater conservation. Yet many are historically significant waterways, and with a little restoration and care can become ecologically robust and a source of recreation for city dwellers. Opanuku Stream is one of two West Auckland streams singled out for special attention by Waitakere City Council. Rising in the lush surrounds of the Waitakere Ranges, it cascades down a series of rocky precipices before levelling out and flowing through Henderson Valley, eventually reaching the Waitemata Harbour at Te Atatu. With ropes, paddles and an eye for adventure, a group of Aucklanders has traced its varied course.

Written by       Photographed by Martin Hill

On sodden ropes I inched down the wa­terfall, wondering how I would negoti­ate the deep pool at its base. I swung myself across to a slippery boulder, and noticed as I did so a sinuous shape in the water. It was the largest eel I had ever seen, beige in colour, with a head as big as my fist. I was transfixed, but the eel seemed unfazed by my presence. It had possibly never encountered a human being before.

I was halfway through a near-vertical descent from a ridge of Auckland’s Waitakere Ranges into Hend­erson Valley—the most challenging part of a journey which had begun simply with the idea of paddling the Opanuku Stream by kayak. But the idea had grown. I had decided to explore the stream’s headwaters as well: to travel from source to sea.

The Opanuku Stream is one of many which begin high in the Waitakeres, the hills that flank Auckland’s western suburbs. These streams flow in three basic di­rections: west, to the Tasman Sea, south, to the Manu­kau Harbour and east to the Waitemata Harbour. The Opanuku eventually joins the tidal waters of Henderson Creek, emptying into the Waitemata at Te Atatu.

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On this late autumn day the source of the Opanuku was a nondescript trickle that made its way sluggishly along a ridge through dense forest. When two small tributaries joined it, the stream gathered strength and swept past private properties to the edge of a bluff.

Our small party—Martin Hill, photographer, Len Gillman, forest ecologist, and I—worked our way along the bluff to a point where our topographical map indi­cated the drop was 160 m. We could just make out the valley below, but once we started the descent the forest canopy closed over us, lush and dripping. Where our climbing ropes ran over rock we worried about getting them down after us: if they became jammed, one of us would have to climb back up to free them.

“I’m going to test that the rope will pull free,” came Hill’s voice on the two-way radio I was carrying. He was 15 m below me and out of sight, and I was last down on this section. I could barely hear him above the sound of the waterfall. The rope slithered round the anchor tree a bit and the OK came.

When I reached the bottom we pulled the rope down and rigged the next tree abseil—the sixth. It took all day to get down to where the stream began to level out. With half an hour to darkness we coiled the ropes for the last time and waded through the shallows and pools looking for the confluence with Spragg Stream.

Two huge kauri loomed out of the shadows. I won­dered how they had escaped the loggers’ rampage through the lower slopes of the Waitakeres. All these hills would once have been thick with kauri—to settlers’ eyes, there for the taking. The trees were felled and dragged or rolled to the nearest stream. Driving dams built at strategic points on the waterways were tripped sequentially to create a deluge that carried the logs down to the sawmills.

We waded downstream, passing the confluences with Pukearuhe Stream and Stoney Creek, which, with Spragg Stream, probably had driving dams in the old days. Now they are once again an undisturbed habitat for such creatures as the banded kokopu. This native fish hides by day under overhanging bush, emerging at night to lie in wait for prey, typically the larvae of aquatic insects, or land invertebrates, such as caterpillars or spiders, that fall into the water. Still listed by the Depart­ment of Conservation as a threatened species, over the past 10 years it has been recorded with increasing fre­quency in Auckland’s modified urban streams, where it uses watercress for shelter if there is no bush cover. Like eels, banded kokopu are effective climbers, using their pectoral fins to make their way up culverts, pipes, dams and rocky surfaces.

The water level was low for May. At times we waded through pools waist deep, but more often we were in stony reaches no more than ankle deep.

Packs aloft, the author (left) and Ruby Jones, a freshwater ecologist, negotiate one of many fern-fringed pools in the upper section of the Opanuku.
Packs aloft, the author (left) and Ruby Jones, a freshwater ecologist, negotiate one of many fern-fringed pools in the upper section of the Opanuku.

From the debris we began to encounter we knew we had crossed the boundary of the Waitakere Ranges Re­gional Park and were entering an area of human habita­tion. Bits of black polythene were evidence of a nearby plant nursery; several drowned chickens indicated the presence of a poultry farm.

Wherever there were houses and farms there were weeds: blackberry, wattle, privet, wild ginger, Montbretia, wandering Jew. The further downstream we pushed, the more varied they became.

Just before Carey Park the Parekura Stream joins the Opanuku. Legend recounts how the warrior Nihotupu raided the gardens of a chief named Panuku, near Te Henga (Bethells), and not only stole his ripe gourds but kidnapped his wife, Parekura, as well. A trail of feathers plucked by Parekura from her cloak and strewn on the ground led her enraged husband to a cave where Niho­tupu had taken her. In the battle that followed, Panuku challenged and killed Nihotupu. Three stream names recall the incident: Parekura, Nihotupu and Opanuku.

Carey Park is now an adventure camp, but in the 1920s it offered more sedate pastimes. It was called Fern­dale, “the beauty spot of Henderson Valley,” and was a popular destination for townspeople, who came to picnic and swim at the swimming hole and take afternoon tea at the Brown Owl Tea Rooms.

It was here that Ruby Jones, a freshwater ecologist, joined us. Jones is a coordinator for Wai Care, a scheme Waitakere City Council and Auckland City Council have developed for monitoring water quality. She and her col­leagues teach community groups, schools, land‑owners and others how to make habitat assessments and do chemical, flow and biological tests. The data collect­ed enable planners to make informed decisions on ways to restore and protect Auckland’s freshwater resources.

Near Palomino Drive, Henderson Valley, a resident walks her horses and dogs down to the Opanuku—too shallow here for uninterrupted paddling.
Near Palomino Drive, Henderson Valley, a resident walks her horses and dogs down to the Opanuku—too shallow here for uninterrupted paddling.

In a freshwater ecosystem, Jones explained, some invertebrates are extremely sensitive to pollution, while others are tolerant to varying degrees. Identifying the inhabitants of a waterway gives an indication of its eco­logical “health.”

Jones waded into the stream and started turning over rocks, her sample net poised. She made a sudden dip and scooped up a creature she identified as the nymph of a dobsonfly. “It’s known as the ‘toe-biter,’” she said, “on account of its large jaws and habit of nipping bare feet.”

Just before nightfall, kayaker Greg Jack pulled into our campsite with four kayaks stacked on his roof rack. We lined them up on the bank, ready for the morning, and continued looking for stream creatures.

Jack spotted a trail of light in the water. “Turn off your head-torch, quick,” he said. It was a tiny freshwa­ter limpet. Moving the stones had caused it to release luminous mucus—a defence mechanism against preda­tors such as eels. The glowing goo is carried away by the current and diverts the predator’s attention. Found only in the North Island, the limpet is one of very few freshwater bioluminescent animals in the world.

[Chapter Break]

Raindrops on the tent in the early hours of the morning woke me, and I listened to the sound of the stream, trying to visualise its flow. At first light I was relieved to see it was still an innocent trickle.

We slipped the kayaks into the wa­ter, but no sooner had we paddled a few strokes to round a bend than we had to get out and drag them across a shingly section. Again and again this happened over the following hours.

We came to a sizeable pool, and I wondered if this was where Bill Bond had launched the boats he used to make out of a sheet of corrugated iron, curved to a point at the front, with a plank of wood set across the back for the stern.

The once ubiquitous freshwater crayfish, or koura, can still be found in the Opanuku—a sign that, despite being used as dumping grounds, suburban streams can still sustain a healthy complement of plants and animals.
The once ubiquitous freshwater crayfish, or koura, can still be found in the Opanuku—a sign that, despite being used as dumping grounds, suburban streams can still sustain a healthy complement of plants and animals.

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Bond had talked to me about the stream before we started exploring it. Born in 1917, he told me he had lived beside the Opanuku most of his life. The family farm ran down to its banks, and he spent a lot of time playing there as a child.

“My favourite thing was turning over rocks covered in tendrils of green slime,” he said. “At certain times of year you’d find hundreds of baby eels under them.”

He recalled a flood in the late 1920s. “I set off down the hill, through the scrub, along the road to the wooden bridge at Candia Road. The water was flow­ing over the deck, which was usually 20 feet above the bank, outdoor chairs and a sun umbrella at the bottom of someone’s garden. Alarmed pukeko squawked and hur­ried away, and a group of mallard kept their distance in the water ahead of us, taking to the air if we got too close but landing again just around the next bend.

Stormwater pipes emptying into the stream added to the sound of rushing water. Logs piled up on the bends had snagged the debris of human settlement: disposable nappies, cardboard, drink bottles. In the logging days, kauri logs might have jammed up along this stretch, and bullocks would have been needed to free them.

The stream was moving along at a good pace, and paddling sections were becoming longer than portages. The kayaks slid over obstructions instead of bumping into them.

A paddling of mallards is an indicator that, as habitat and larder, the Opanuku meets a duck’s needs.
A paddling of mallards is an indicator that, as habitat and larder, the
Opanuku meets a duck’s needs.

At the Border Road bridge we met up with ento­mologist Stephen Moore, who was catching freshwater creatures to show us. Among these were Cran’s bullies, freshwater mussels, crabs and crayfish (koura), and an eel water level. The water was up to my knees. I could feel the bridge moving, and the railings had buckled. Next morning when we looked out it was gone.”

Several other bridges in the district had been swept away that night, he said, and the floodwaters had shifted a dance hall at Ferndale off its foundations and turned it around while the owners, a Mr and Mrs Knight, were asleep in it. It came to rest up against some manuka trees on land owned by the Bonds. The first thing the Knights knew about it was when they couldn’t open their door in the morning. They subsequently bought the land their building had settled on, jacked the place up and built another storey underneath.

Our stop-start progress downstream continued. Branches frequently blocked the way, but when the sun shone the forest sparkled. Each new bend—and there were many—brought a surprise: a frayed rope swing dangling over the water, two white goats tethered on the which had taken up residence in a bottle.

“I was admiring the bottle, actually,” laughed Moore, “when I saw this face staring out at me. It’s a young eel, a yellow belly, probably about two years old.”

The water quality seemed good, he said. “Some of the 30-odd animals I’ve collected are always associated with cool, clear water, high in dissolved oxygen. I’m quite surprised at the number of different types of mayfly. Stoneflies, too. The presence of these most sensitive groups indicates the water is clean—in this section of the river, at any rate.”

From atop a stormwater pipe, Ben Copedo, who guides historical walks in the Henderson area, describes local features to the paddlers. Yet another supermarket trolley has been sent to a watery grave here—sad testimony to the low regard many people have for the streams of suburbia.
From atop a stormwater pipe, Ben Copedo, who guides historical walks in the Henderson area, describes local features to the paddlers. Yet another supermarket trolley has been sent to a watery grave here—sad testimony to the low regard many people have for the streams of suburbia.
A pair of bridges—for pedestrians (background) and vehicles (foreground)—span the Opanuku at Great North Road. Kauri logs would once have thundered down this stretch of water on their way to Henderson’s Mill, but now the stream sees little traffic of any sort. With its sister stream, the Oratia, the Opanuku has become the focus of a project by Waitakere City Council to improve public awareness of the city’s waterways and inspire greater efforts to conserve them.
A pair of bridges—for pedestrians (background) and vehicles (foreground)—span the Opanuku at Great North Road. Kauri logs would once have thundered down this stretch of water on their way to Henderson’s Mill, but now the stream sees little traffic of any sort. With its sister stream, the Oratia, the Opanuku has become the focus of a project by Waitakere City Council to improve public awareness of the city’s waterways and inspire greater efforts to conserve them.

Moore waded out to push us off into the current and wished us well. The stream was becoming swollen and clay-coloured. We could hear cars in the distance, but no one was walking the riverside track.

At a sharp bend, a big pine had been undermined by the stream and toppled. On the next sharp bend a young totara, leaning at a 20-degree angle, was being subjected to the same process—proof of the scouring power of moving water.

Henderson’s Mill Bridge was a welcome sight as we rounded the last bend. The mill was built in 1849 but closed down in 1866, after all the accessible kauri had been cleared. Of the mill buildings, only the cookhouse remains, a cottage that now houses the West Auckland Historical Society. A replica water wheel, its housing vandalised and tagged, is a reminder of the 5 m wheel that once turned the mill’s saws.

[Chapter Break]

Next day it was a simple matter to paddle the few hundred metres to the confluence of the Opanuku and Oratia Streams, where they become Henderson Creek. There was once a landing at this point, and up until the 1890s the waterway served as the main means of communication with Auckland, since Great North Road was notoriously unreliable.

A huge flood in 1876 burst the mill dam, hurling metre-thick kauri logs across the surrounding paddocks. Large sections of stream bank were washed away, and for a few hours the waters of the Opanuku and Oratia met 800 m further upstream than normal.

At the confluence we left the Opanuku and took a diversion up the Oratia Stream, passing Tui Glen, which opened in 1924 as New Zealand’s first motor camp, of­fering 40 different amusements from carpet bowls to donkey rides. It closed down in 2001.

Emphasising the conservation ethic, local Maori have erected a pou rahui on the bank of the Opanuku, visible to all who use the river.

The Oratia and Opanuku are the two streams of Waitakere City Council’s Project Twin Streams, one of several schemes the council has launched in a bid to restore “green corridors”—unbroken stretches of native vegetation—from the ranges to the sea. Such corridors are needed, says the council’s Green Network commu­nity project coordinator, Chris Ferkins, because many native animals will not move from one discrete patch of native forest to another across unforested land. They become ecologically marooned.

“Since streams form a natural pathway over a long dis­tance, it makes sense to base restoration around them,” says Ferkins. Among the project’s activities are the clear­ing and replanting of stream banks, the establishment of wetlands and detention ponds to deal with stormwater run-off containing sediment and pollutants, and community education about water-quality issues.

Stream-bank restoration not only has an ecological pay-off, but also reduces flooding and controls erosion. Wading upstream, we came to a section of steep bank near the Henderson shopping area that had been planted with natives by volunteer groups three years before under Project Twin Streams. Formerly weed infested, it was now a tiered native planting. Along the edge of the stream were cabbage trees, toetoe and native sedges; above the flood line were flax, pittosporum and hoheria; and further back, under an already existing canopy of kanuka and pest species such as tree priv­et and wattle, had been planted mainly kawakawa and hangehange. The pest species had been left to provide stability while the new plants became established.

A week later we returned to the confluence of the twin streams, this time with sea kayaks and a couple of keen birdwatchers. The mayor of Waitakere City, Bob Harvey, had also agreed to paddle the last leg with us in his outrig­ger canoe.

We launched into the stream on the full tide and Harvey took the lead. A familiar sight around Henderson, he was soon attracting notice. A local leaned over the bridge to call “Gidday, Bob!” and a couple called a greeting from the walking path that fol­lows the creek as far as the motorway.

Together with council-led initiatives, this move bodes well for the stream and its residents—including a pair of white-faced herons waiting for the tide to drop before feeding on mudflats near the Opanuku’s mouth.
Together with council-led initiatives, this move bodes well for the stream and its residents—including a pair of white-faced herons waiting for the tide to drop before feeding on mudflats near the Opanuku’s mouth.

We paddled along quietly past the fringing man­groves, the calm surface of the water disrupted now and again by competition kayakers powering by and a water-skier practising his turns. Suburban houses crowded together on the banks, vying for a frontage, and white-faced herons stalked delicately across the mud banks.

We passed the South Pacific Television studios, home of Shortland Street, and under the gaze of the “guard­ian of the river.” This imposing carved figure is a pou rahui, a conservation post, explained Rewi Spraggon, a representative of one of the local iwi, Te Kawerau a Maki, when I talked to him later. “It’s a physical remembrance of the use of the creek by Maori as a pathway,” he said. “It repre­sents our mana whenua.”

As we passed under the north-western motorway, the river widened, its waters blending with those of the Waitemata. The city’s icons, the Skytower and Har­bour Bridge, came into view. The journey was over.

I laid my paddle across the kayak’s deck and thought about the value of suburban streams like the Opanuku: of the life they sustain, the history they embody, the abuse they’ve seen, the pleasure they provide. I thought about the beige eel in its secluded pool. How long ago did it make its way up to its forested retreat? How long would it be before, having grown fat on its diet of weta, koura, rodents and fish, it retraced its passage to the harbour? I knew it faced a much longer journey than the one I had undertaken: it would swim onwards to its spawning grounds in the tropical Pacific, to breed and die.

The cycle of an eel; the life of a river. Intertwined. Something to cherish.

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