Not for sale

River group wants 3 per cent more water from Manapouri power scheme to restore Waiau river.

A community initiative to restore the mana of a once mighty river is gaining momentum in Southland.

The Waiau Rivercare Group (WRG), which became an incorporated society just over a year ago, now has more than 400 members and is fighting for the river's rights in the Environment Court.

At the same time individual farmers are acting to improve the river's health. WRG co-chairman Paul Marshall says he is aware of a significant number of farmers who are undertaking riparian planting to help reduce nutrient flow into the river's water.

"In our patch, farmers have an absolute commitment to improving environmental outcomes," he says. "There has been a seismic shift in this in the last few years."

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Just 3 percent more water would improve the health of their river says Paul Marshall. Photo / Supplied
Just 3 percent more water would improve the health of their river says Paul Marshall. Photo / Supplied

He says workshops have been held to encourage farmers to draft and implement farm environment plans and from what he has seen "farmers have strongly risen to this challenge."

The Waiau is the largest river in Southland, running from Lakes Te Anau and Manapōuri, 70 km south to its outlet in Foveaux Strait near Tuatapere, west of Invercargill. It was once also New Zealand's second largest river by volume (after the Clutha/Mata-Au) but, since the opening of the Manapōuri power scheme in the late 1960s, the group say it's been a shadow of its former self.

Marshall, who farms over 1400 dairy cows near Tuatapere, says the group is concerned about the ecological health of the lower Waiau because of the amount of water diverted away from the river into the Manapōuri power station. He says an average of just five per cent of the river's original flow runs to the sea in Southland, with the remainder of the water diverted through the massive underground power station and discharged into Doubtful Sound.

"Before the dam opened in 1969, the average flow in the river was between 450 and 500 cubic metres per second [cumecs]. If you imagine a cubic metre as being equal to a bale of wool, imagine 500 bales of wool going past every second. The minimum flow now is 13 to 16 cumecs, depending on the time of year," Marshall says.

Paul Marshall and Roseanne Allen of the Waiau Rivercare Group. Photo / Supplied
Paul Marshall and Roseanne Allen of the Waiau Rivercare Group. Photo / Supplied

While the Save Manapouri campaign of the 1960s and 70s might have stopped the lake's level being raised to generate more power, "in the process they allowed the lower Waiau to be turned into a drainage channel."

The WRG was originally formed in 2017 and its activity and influence have steadily grown. It now has around 420 members, ranging in age from 7 to 94, including farmers and rural residents and those who live in towns throughout the Waiau catchment.

The group is concerned about the environmental effects of the drastically reduced river flow, which include blooms of toxic algae, including benthic cyanobacteria. The river is also infected with didymo or rock snot, a tissue-like algae first seen in New Zealand rivers in the early 2000s. While not poisonous, didymo infestations are unsightly and make it unpleasant to fish or swim in the river.

"It's like someone standing upstream of you, tearing off strips of toilet paper and throwing them in the water — it's really yuck," Marshall says. "It makes fishing almost impossible, not only because it catches on lines and hooks, but it also smothers the invertebrate community in the river, which is what the trout primarily feed on, not to mention the native fish."

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Marshall says while the presence of didymo cannot be blamed on power company Meridian Energy, it does have the ability to send regular "flushing flows" down the Waiau, which would shear off a lot of the didymo build-up and wash it out to sea.

The low river-water flow has also caused sedimentation of the Te Waewae Lagoon, where the river meets the sea, and has changed the profile and removed the sand from Bluecliffs Beach at its mouth. Marshall says what once was a rich, sandy habitat, home to millions of toheroa, is now rocky cobbles. He adds that when the river is naturally running high, such as during February's record rainfall, sand is deposited back on the beach.

Locals use the Lower Waiau for fishing, swimming and boating. Photo / Supplied
Locals use the Lower Waiau for fishing, swimming and boating. Photo / Supplied

Last year was a busy one for the WRG, with representatives feeding back on the government's Essential Freshwater Package. Marshall says the WRG's submissions have protested the exemption of Manapōuri and other large hydro schemes from freshwater management requirements.

It also ran a T-shirt design competition for local young people, receiving 132 entries. A graphic designer then incorporated aspects from the top 10 designs to create a logo for the WRG, and 100 T-shirts were printed and sold.

"At the bottom of the logo is the whakataukī 'Ko au te awa, ko te awa ko au' — I am the river and the river is me — which encapsulates exactly what the Waiau Rivercare Group is about," Marshall says.

The group believes allocating just 3.4 per cent more water to the Waiau (raising the minimum flow to 35 cumecs) would make a significant ecological difference – and has come up with the social media hashtag "#just3percent" to sum up its goal.

"We're looking for the sweet spot — we don't want to close down Manapōuri, we just want to have a little bit more water going back into the Waiau River. It's not a hell of a lot, but we need the mana of our awa to be restored," Marshall says.

"Fundamentally, we want our tamariki and mokopuna to be able to fish in it and to be able to swim in it. For us, the welfare of the river is critical, and it's absolutely intergenerational. We will not be defeated, and we will not give up."