The country has a storage problem, not a generation problem. New Zealand has enough turbines, enough wind farms, enough geothermal stations and enough rooftop solar to run the electricity system most of the year. What it does not have is enough stored energy to ride out a dry winter without burning gas at Huntly, or to firm the next decade of intermittent renewables that policy is asking the system to absorb.
The cheapest way to fix that problem, by a wide margin, is to dam the outlet of Lake Wakatipu at Kawarau Falls and raise the lake by ten metres. The cost is Glenorchy, the lower bays of the Frankton arm, and the willingness of the country to do what it has not done since Cromwell. Here is the case for doing it.
The country needs storage, not generation
New Zealand’s electricity system runs on roughly 42 terawatt hours of generation a year, of which about 60 percent is hydro. In a normal hydrological year, that mix works. In a dry year, when the Mackenzie and Clutha catchments fill at 70 percent of normal, it does not. The country has to either burn gas at Huntly, or burn coal at Huntly, or run short. In 2024 it burnt both.
The reason it has to do that is not a lack of generation capacity. It is a lack of stored water. Total existing hydro storage in New Zealand sits at about 4 terawatt hours, of which the Waitaki lakes hold most. That is enough to ride out about six weeks of dry. A real dry year is six months. The gap between those two numbers is the entire reason the country still has its biggest gas station running, and the reason every electrification scenario ever modelled by the Climate Change Commission assumes either much more storage or much more gas.
The country is choosing between those two options now, whether or not it admits the choice.
Why Wakatipu is the answer
Lake Wakatipu is 80 kilometres long, 380 metres deep and holds about 95 cubic kilometres of water at its current level. It is the largest deep water lake by volume in New Zealand and one of the largest in the Southern Hemisphere. Its water already runs through the existing Clutha hydroelectric chain via the Kawarau River, the Cromwell junction, Lake Dunstan and the Clyde and Roxburgh power stations. The turbines exist. The transmission exists. The catchment exists. What does not exist is a controlled outlet.
Build that outlet at Kawarau Falls, the natural chokepoint at the south end of the lake, and raise Wakatipu by ten metres. The lake’s surface area of around 291 square kilometres means a ten metre raise captures roughly 2.9 cubic kilometres of additional water. Released through the Clyde and Roxburgh stations on demand, that volume is worth approximately 1.5 terawatt hours of stored energy.
That single figure is what the argument turns on. New Zealand’s existing total hydro storage is 4 terawatt hours. Wakatipu alone would add 1.5 to that, a 37 percent increase in the country’s strategic energy reserve, from a project that requires zero new turbines and zero new transmission lines. There is no other site in the country that offers anything like that ratio of effort to outcome.
Lake Onslow, the proposed pumped storage scheme killed by the coalition government in 2023, was costed at around 16 billion dollars to deliver about 5 terawatt hours of storage on a remote Otago basin with no existing infrastructure. Wakatipu would deliver roughly a third of that storage at roughly a fifth of the cost, on a site that already feeds the grid. The numbers are not close.
Where the power actually goes
Most of New Zealand’s hydro generation sits in the South Island. Most of New Zealand’s electricity demand sits in the North. The HVDC Inter-Island link carries the difference, and most of what it carries ends up in the upper North Island, with Auckland the single largest concentration of load on the national grid.
Auckland accounts for around a quarter of the country’s electricity demand and is the part of the country growing fastest in both population and the electrification of its transport, heating and industry. The city has no significant local hydro generation. Its biggest local generator is Huntly, which burns coal and gas to make up the gap between what the country’s clean stations can deliver and what Auckland actually uses.
The storage gained at Wakatipu does not, in any practical sense, keep Queenstown’s lights on. Queenstown is already well supplied by the local distribution network. The storage gained at Wakatipu sits in the lake until a dry winter or a windless week, at which point it is released through the Clyde and Roxburgh stations, sent up the country on the HVDC line and delivered to Auckland’s heat pumps, EV chargers, hospitals and factories. That is the actual transaction this argument is about. The South Island holds the water. The North Island holds the people. Glenorchy is the cost of Auckland keeping its transition to clean electricity moving.
What it costs in money
A controlled outlet dam at Kawarau Falls is a small civil engineering project. Estimates for comparable lake-outlet works put the construction cost at 300 to 500 million dollars. Property buyouts at Glenorchy, where about 1,000 people live and a few hundred buildings sit at lake level, plus the lower Frankton arm bays and the Queenstown waterfront below the 320 metre contour, would be the largest cost. At a 150 percent of market value premium, which is more generous than the country has ever offered in any previous flood-line buyout, the total property bill is probably 3 to 5 billion dollars. Relocated road and infrastructure adds another 500 million to a billion.
The total cost of the project, with the engineering deliberately on the high side and the buyouts deliberately generous, is somewhere between 4 and 7 billion dollars. The Onslow proposal was 16. The avoided cost of burning gas for the next 30 years to cover the same storage gap is somewhere between 20 and 40 billion, depending on the carbon price.
This is the cheapest piece of major energy infrastructure New Zealand will ever build.
What it costs in towns
This is the hard part of the argument and the part that everyone reaches for first. So address it directly.
Glenorchy is a settlement of about 1,000 people at the head of Lake Wakatipu. It is a beautiful place, a gateway to the Routeburn and the Dart, and the centre of a small but real community. A ten metre raise of the lake puts most of the township under water. The Routeburn trailhead, the Dart River jet boat operation, the Glenorchy Hotel, the red shed at the wharf and the residential streets along the lake edge are all gone. People are relocated. Some land is acquired by the Crown. Some businesses move higher up the valley or to the new shoreline. The community continues, in a different physical form.
The lower Frankton arm of Queenstown is more complicated. Parts of Kelvin Heights, the lakefront below the 320 metre contour at central Queenstown, the Queenstown gardens spit, and the lower campground sites all go under. The Queenstown CBD itself sits high enough above the lake that it survives, but the immediate waterfront does not. Maybe 5,000 to 8,000 people would need to be relocated or have their properties acquired, almost all of them on the wealthier side of the country’s wealth distribution.
The displacement is real. So was Cromwell’s. The argument for doing it anyway is that the alternative is keeping the country structurally dependent on imported gas through the entire transition to electrified transport and industry, and accepting the emissions that go with that, for the benefit of preserving a specific lake shore in a specific resort town.
The tourism argument is not as strong as it looks
The instinctive defence of the current shoreline is tourism. Queenstown and Glenorchy together draw several million visitors a year. Tourism revenue from the Queenstown Lakes district is significant in the national accounts. The argument runs that drowning the shoreline destroys the asset that generates that revenue.
It is not that simple. Lake Wakatipu does not disappear in this scenario. It gets larger. The Remarkables still rise above it. The Routeburn still walks above it. The skiing is unaffected. The Dart and Rees river deltas are reshaped at higher elevation, but the jet boats still run. Glenorchy is rebuilt 50 to 100 metres further up the valley, on a new lake shore. Queenstown’s waterfront moves 200 metres back. The town remains an alpine resort on the edge of a long deep lake. The lake is just deeper.
There would be a transition cost during construction. There would be permanent changes to certain views. Some specific photographs people associate with the area would no longer be possible to take. None of that adds up to the loss of a tourism industry. The Mackenzie Basin still attracts millions of visitors despite Lake Pukaki being a hydro reservoir. Lake Hāwea was raised 20 metres in 1958 and people still buy houses on its shore. Tourism adapts.
The honest comparison
The country’s actual choice, the one that exists whether or not the country makes it explicit, is between drowning a piece of well-photographed lake shore and not drowning it. Choosing the second is choosing more gas, more coal, more imported LNG, more methane emissions and a slower transition for the rest of the economy, particularly Auckland, where most of the demand actually lives. Choosing the first is choosing the largest single addition to the country’s strategic energy storage that has ever been on the table at the cheapest cost per stored kilowatt hour.
Newswire’s view is that the second choice is the one that should be argued against. Glenorchy at 1,000 people, with a properly negotiated relocation and a generous buyout, is the price of taking the country’s climate target seriously. The alternative, of preserving a particular waterline for the benefit of property owners and visitors who chose to be there in the last 30 years, is the genuinely radical option. It implies that those people’s view of the lake outranks the country’s strategic energy security and its emission obligations for the next century.
This is the argument the country should be having. Whether or not it likes the conclusion.
For context on where Wakatipu sits in the wider grid, Newswire’s NZ Grid Live tool shows live generation across the existing 76 stations, including the Clyde and Roxburgh stations that would do the work if this project were built. With the general election in October, our voting tool compares the parties on energy, infrastructure and climate policy.
Are you for or against the case made here? Tell us in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
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