Where we used to swim: The inky blackness of the Tarawera

Wednesday, 25 December 2019

The inky darkness of the Tarawera River has slowly begun to clear, Georgia-May Gilbertson reports.

From the beauty of the Tarawera Falls, the Tarawera River's colours swirl into a gentle flow, similar to that of a water colour painting.

But further down, as it weaves its way through the forestry settlement of Kawerau, its pastel colours begin to mix into an inky darkness.

The river has been nicknamed 'the black drain' since the 1990s after pulp and paper mill Norske Skog was found to have been discharging into the river since the 1950s.

Back in 1997, the mill, and other sources in the areas, was discharging a reported 160 million litres of industrial waste into the river a day, but science manager at the Bay of Plenty Regional Council Rob Donald said work had been done to improve the river's well-being.

**READ MORE:

* Swimming spots not so pristine

The Norske Skog Tasman Pulp and paper Mill at Kawerau in the Central North Island

* Where we used to swim: Lake Horowhenua

* Where we used to swim: Pandora Pond

* Where we used to swim: Waipoua River

* Where we used to swim: Selwyn River**

The Tasman newsprint mill at Kawerau with wetlands and thermal power station in the foreground.

'Colour and clarity was one of the main issues which is how the nickname 'the black drain' came about. The other issue was organochlorines and there was a lot of emotion around that,' Donald said.

'The colour and clarity was mainly due to the natural compounds that were taken out of the water and then discharged into the river, so tannins cause that sort of murky, browny-black appearance. This only really exists because of the mills.'

The Tarawera Falls further upstream on the Tarawera River

Donald said a regional plan was put in place to reduce the dark colour and improve water quality and oxygen levels within the river.

'The plan to target colour has only just been met, but back in the year 2000, the colour was pretty much double what it is now. It still looks quite dark, but it has more a yellow tinge to it as opposed to a brown/black.'

Donald said the improvements in colour and quality were due to changes in the mill, including reduced production and technology.

'There's been closures of certain pieces of equipment including two of their newsprint machines and they've changed their bleaching processes as well,

'Colour relates to swimming, so if the river is dark then there's no way people are going to swim in it.'

However, Donald said swimming had never been popular beyond the mill, but it was a different story further upstream.

'Swimming further downstream is considered to be quite dangerous, the river is U-shaped and it's quite deep. People tend to swim further upstream as they can see the bottom of the river and it's a lot clearer.'

The colour quality worsened further downstream, due to the fact it flowed through a former wetland as well as run-off from dairy farms.

'The colour doesn't so much affect the aquatic life, it's more relevant to the plants that live on the bed of the river. But fish life of course need light and clarity to be able to see their prey.

'The river is polluted, but it certainly looks a lot worse than what it is. It's the things you can't see that you should be worried about and those were the organochlorines which are dissolved in the water. But the concentration levels of those are not an issue anymore due to technology changes in the mill.'

The Lawa website showed two monitored sites down from the mill and noted 'the water is discoloured and not suitable for swimming'.