Tiwai Point is a polarising place, people tend to love it or hate it. 2021 will be its 50th year of operations, it could also be the smelter's last. Eyewitness follows the history of the Tiwai Point aluminium smelter.

The first of Tiwai Point's pots were fired up on the 23rd of April, 1971.

But the story of the smelter starts at least a decade earlier.

Tiwai Point opened in April 1971.

In 1960, the New Zealand government signed an agreement with Consolidated Zinc, giving the Australian mining company the go-ahead to build a smelter on Tiwai Point and a hydro-electric power station to fuel it at Lake Manapōuri, in the nearby Fiordland National Park.

Listen to Tiwai Point: Fifty Years in the Furnace

By 1963, the company realised it couldn't afford to build both a smelter and a power plant, so the New Zealand government, led by Sir Keith Holyoake, agreed to build the power station.

It was the start of a partnership that has spanned half a century and has had its ups and downs.

In July 2020, the company, now Rio Tinto, announced it would be terminating its contract with Meridian Energy, the current owners of the Manapōuri power station, and closing down the smelter.

A reduction line at Tiwai Point

Rio Tinto has cited high transmission costs as the reason, but Meridian says it offered the company $60m of savings.

But even back in the 1960s the company, which was then called Comalco, was asking for more than New Zealand wanted to give.

Sir Alan Mark

It wanted to raise the level of Lake Manapōuri, which sits in the protected Fiordland National Park, to increase power production. Initially, the government agreed, but the public wasn't happy. After huge protests - the biggest the country has ever seen - the lakes were saved.

Sir Alan Mark, now an emeritus professor at Otago University, was a young botanist in the late 1960s. He oversaw the research into what raising the lakes might mean for the surrounding area.

"By our assessment the increase in lake levels would only increase the annual generation of electricity by 4.5 percent," said Sir Alan, "(But) the cost ecologically, environmentally and aesthetically would have been major."

Sir Alan went public with his findings. Meetings were held and protests staged. One petition put together by Forest and Bird recorded 250,000 signatures, which equated to about 10 percent of the population of New Zealand.

"It was very obvious that the public of New Zealand was strongly opposed to the lake raising," said Sir Alan.

Amongst all the controversy, Comalco was getting on with building its smelter at Tiwai.

Construction begins at Tiwai Point…

Go to this episode on rnz.co.nz for more details