Mysteries of Lake Pūkaki keep public enthralled

You may think you know Canterbury’s hydro lakes like the back of your hand – but did you know that Lake Pūkaki used to boast a small-but-famous island? So famous was the island in its time, that it was on the New Zealand five-pound note for more than three decades...

Five-Pound Note Island was frequently painted and photographed by European settlers throughout the 19th and 20th centuries.

It was said to have native plants covering it, such as species of Kōwhai, with a gravel foreshore.

It existed near the south-western end of the mammoth 15 km body of water – clearly visible from land – until the lake was raised 9 m in 1952 to increase the lake’s storage, preparing for hydroelectrical advancement.

The lake level was raised again in 1976 for storage in preparation for hydroelectric capacity, this time by 37 m, submerging Five Pound Note Island.

Little is known today about the island – its size is unknown, and even pinpointing its exact location seemingly cannot be done. And if you search Five Pound Note Island on Google, a myriad of conflicting results awaits.

Guardians of the lake

Five Pound Island is a stark reminder of looking after what is right in front of us. Kaitiakitanga/guardianship of our natural assets has never been as important as it is today.

The ways in which we can accomplish that are simple, said Upper Waitaki Zone Water Committee chair Simon Cameron. Even planning our trips to the lakes and packing our picnics to reduce food and drink rubbish is a huge stride in the right direction.

“We’re trying to be proactive about this rather than reactive after the fact. It’s a long summer and hopefully when February or March rolls around they’re (the lakes are) still in great condition.

“All of the community thinks the lakes are pretty special, we’ve grown up knowing they’re swimmable and fishable and looking after those areas knowing we have to look after them.

"Everyone - locals and holidaymakers, all have to band together to look after them,” he said.

Powerful Lakes

Pūkaki, meaning ‘source of stream’ in Māori, is one of three roughly parallel alpine lakes running along the northern edge of the Mackenzie Basin – Tekapo and Ōhau are the other two.

They are three of six lakes harnessed as reservoirs for hydroelectric generation in the Upper Waitaki Hydroelectric Scheme, run by Meridian Energy.

The Scheme in itself provided thousands of jobs during the construction of dams, canals and Lake Ruataniwha, and eventuated in the construction of Twizel in the late 1960s, where more than 2000 people now reside.

Altogether the Scheme provides 20 per cent of New Zealand’s yearly power.

Pūkaki and Tekapo generate a combined 50 per cent of the country’s hydroelectricity power.

The power of water knows no bounds - and this video proves it.

Lake Pūkaki is also a culturally important site for local Iwi and Rūnanga.

What the Rūnanga have to say

Te Rūnanga o Moeraki kaumatua David Higgins said the lake is a tīpuna/ancestor and therefore has a special place in the hearts of iwi.

“It’s one of the many ancestral lakes that connects us to our land and our maunga (mountains).

“It was also one of the many resource-gathering sites. We had pā (villages) interspersed around the lake edge, one was where the Pūkaki village is today.

“But those alpine-fed or glacial-fed lakes are all places where our people would have stopped and rested on their way to mahinga kai sites and back,” he said.

Historically, the lake has been used for mahinga kai (gathering or cultivating). Punatahu, at the southernmost point of the lake, is a kāinga mahinga kai (place of gathering) where tuna (eels) and birds were gathered.

According to Māori lore, Pūkaki was one of the lakes dug by the Waitaha explorer Rākaihautū with his kō (Polynesian digging stick) named Tūwhakaroria.

After arriving in the Uruao waka at Whakatū (Nelson), Rākaihautū divided his arrivals into two groups.

Rākaihautū led his group down the middle of the island, digging the freshwater lakes of Te Waipounamu, and his son Rakihouia led the other group down the east coast.

Local Māori have noted there are many sites of cultural significance, including many wāhi tohu/landscape markers, wāhi tapu/sacred places and urupā/burial sites.

What is there to do?

The recreational opportunities of the lake are not lost on the general public. Whether a first-time visitor to the area or visiting the area is a family tradition, Pūkaki is nationally renowned for its salmon farming at the southern end as well as trout fishing on the lake itself.

To the north is the Aoraki/Mount Cook National Park – an otherworldly landscape which lends itself to a range of activities including climbing, walking, tramping and hunting. Guided ski trips and helicopter tours are also available.

The wider area is known for its merino wool, sheep and cattle breeding; and the southern end dam has always been attractive to selfie-snapping tourists and Kiwis alike.


Pūkaki’s frosty Powerade-blue surface is no special effect either – although it may appear that way at first glance.

The lake gets its hue from glacial flour – a fine silt of pulverised rock suspended in the water, reflecting blue light which gives the lake its luminous appearance.

More recently, the lake’s edges were the scene of ‘Lake Town’ in Peter Jackson’s movie adaptation of J.R.R Tolkien’s The Hobbit.

In 2016 the lake was named the third ‘clearest’ in the world by Condé Nast Traveller in just behind rivers in Bonito, Brazil, and the seawaters around the island of Lampedusa in Italy.

A local's take

One of the longest serving families in the area around Lake Pūkaki is the Seymours, who moved to Ferintosh Station in 1936 after stints at Mount Cook Station among others in the immediate area.

Amidst the family’s fond memories on the western banks of the lake were also some of the tough times; including the raising of the lake.

“The property that Ferintosh lost was 3000 acres in the late 1950s (when the lake was raised 9 metres) with no compensation,” Marion Seymour said.

“The next raising was in the late 1970s and that took out another 1000 acres, all most of which was flat land. Because of that it’s now a much hillier station. That would have been be the greatest disappointment – losing all that land.

"(After the second raising) there were battles over compensation and it took a lot of adjusting to try and rethink all the fencing, re-establishing gates, entire buildings; everything had to be rethought.”

But amongst the turmoil that was thrust upon the station – her family’s farm, Marion saw that it was the best thing for the rest of the country.

“Where would New Zealand be today without the hydroelectric aspect? As time went on it became a great foresight from back then, and without it, we’d be lost.

“Without the additional eight power stations it provided, the country’s electricity demands may not have been met.

“The feat of engineering is just incredible when you think about the resources of the time,” she said.

Monitoring water quality

Lake Pūkaki is monitored for water quality in the summer months. Its quality is heavily influenced by its glacial source, with low nutrient concentrations – a good sign of a healthy lake.

Trophic Level Indicator (TLI)

  • Historically the lake has had very good water quality, with a Trophic Level Indicator (TLI) of around 1.5 out of 7 (anything under 2 is determined to be ‘very good’).
  • TLI measures water clarity, chlorophyll content, total phosphorus and total nitrogen. From these parameters a TLI value is calculated.
  • The higher the value, the greater the nutrients and fertility of the water which encourages growth, including algal blooms, meaning higher TLI scores equals poorer water quality.

Improving Biodiversity

Pūkaki is also home to kōaro, upland bully, upland longjaw galaxias, brown trout, rainbow trout, Canterbury galaxias and many other species of fish.

Earlier this year the Upper Waitaki Zone Water Committee pledged $73,000 over three years towards pest control in the Dobson and lower Hopkins Valley, both of which feed into lakes such as Pūkaki.

That will see the likes of crack willow and Russel lupin controlled, while working with landowners, Department of Conservation (DoC), Land Information New Zealand (LINZ) and other stakeholders.

Work has also been undertaken in the Mackenzie Basin this year by the zone committee to improve the survival chances of trout; and water quality issues in the Ahuriri arm of Lake Benmore. Find out more about how we are improving water quality in Lake Benmore.

Can I swim here?

When you’re heading to the local lake this summer, don’t forget to look out for water quality information signs. These will tell you if there’s a health alert in place or whether to avoid swimming if it’s been raining in the past two days.

Environment Canterbury regularly monitors water quality at 100 popular swimming spots around Canterbury. The results are updated weekly, and are available through Land, Air, Water Aotearoa (LAWA), New Zealand's most comprehensive source of water data.

It’s also important to avoid swimming for 48 hours after there has been rainfall. This is because rain can wash bacteria from roads and paddocks into the waterway.

Zone committee chair Simon said with the potential for E.coli contamination over summer, it’s important to be in the right “mindset”.

“It’s mostly Kiwis having holidays out there so we’re trying to get people into that mindset of looking after themselves and taking rubbish-free picnics to and from the lakes.

“It’s really simple, just take things along to the lake that won’t create rubbish – things like non-plastic food wrapping.”

“There are other groups sharing the same concerns as us – the Coastguard is one. That’s all around being boat safe and being vigilant around alcohol mixing with boats, as well as the rubbish aspect. All things to think about,” he said.

Enjoy our lakes this summer. If you’re visiting one of the beautiful waterways, we’re counting on you to dispose of rubbish correctly and use the toilet facilities provided.


Sarah Drummond Photography