On the west of the Southern Alps the rain comes in metres rather than millimetres. The rivers are steep, rocky and gushing. Hydro power seems like a natural fit, a common sense option.
But then there’s the environmental values to take into account — the pristine rainforest, ancient landscapes and unique wildlife.
The looming threat of the Alpine Fault makes any large civil engineering project on the narrow coastal plain a difficult task. But when geography compels the structures be built within cooee of the fault, where the waters rushing off the ranges meet the flat land, the risks and costs of the scheme climb sharply.
Scientists say there is a 75% chance the fault will rupture in the next 50 years, generating a destructive magnitude 8.1 or thereabouts earthquake, followed by damaging aftershocks in the magnitude 7 range which could last for many months.
The effects on the West Coast especially will be huge and long-lasting. Ironically, this is precisely why Coasters need to look locally for likely sources of electricity, even if the best place to build plants is on the very fault which they need to guard against. Winston Churchill’s “riddle, wrapped in a mystery, inside an enigma” sums it up well.
The Coast relies for much of its electricity on the Transpower lines which cross the main divide from Canterbury at Arthur’s Pass. An Alpine Fault quake, or indeed any other major quake, is likely to damage those lines and cut power to the region. A second Transpower connection with Nelson and Marlborough adds some security, but this is also vulnerable to earthquake.
With such fragility, it is little wonder that local distribution company Westpower is seeking additional sources of power. Its 7.6-megawatt Amethyst hydro station near Hari Hari in South Westland has been running since 2013, producing about 50 gigawatt hours of power a year, said to be enough to run 6000 homes and businesses.
Through the government’s fast-tracking process, Westpower has now received draft approval to build a similar but larger run-of-river scheme on the Waitaha River, in the neighbouring valley. This would be a $200 million, 23MW project, which could generate up to 140GWh of electricity annually, enough for another 12,000 households and businesses.
While the proposal seems sensible, there are significant and growing environmental concerns at the potential damage even a low-profile weir on the river and a tunnel could cause to Kiwi Flat and the Morgan Gorge, just east of the Alpine Fault.
The project has had long-standing support from Poutini Ngāi Tahu, comprising Ngāti Makaawhio and Ngāti Waewae, who wrote to the government two years ago urging its fast tracking. However, conservation and recreational groups are deeply worried about the effects of diverting water from the river through the tunnel on the character and amenity value of the schist-filled gorge.
Federation Mountain Clubs president Megan Dimozantos says reducing the river in the gorge to a small residual flow will destroy a unique wilderness area, wreck one of New Zealand’s last untouched wild-river gorges and ruin its ecological values.
FMC, Forest and Bird, Greenpeace, the Canyoning Association, the Buller Tramping Club and former Whitewater NZ president Kev England have signed a letter asking the fast-track expert panel to reconsider its draft decision. Ms Dimozantos said they were not allowed to make a submission, even though the panel accepted the scheme would have significant effects on the gorge and Kiwi Flat.
It’s worth recalling that, in 2019, Labour environment minister David Parker dismissed an application purely on the basis it would affect the intrinsic qualities of the river and its catchment.
There are no easy solutions here. The Coast needs to boost its brittle power grid, the country needs to embrace more renewable energy sources, our wonderful wilderness must be protected, a major earthquake will come.
But Westpower still has work to do to convince everyone that this scheme is the right one at the right time.
