The Canterbury Plains makes a huge contribution to the dairy industry. But, as freshwater ecologist and senior researcher at Victoria University of Wellington Mike Joy explains, it hasn’t always been this way.

“It couldn’t happen without irrigation,” Joy says. “There’s more irrigation in Canterbury than the whole rest of New Zealand put together to make this landscape into a dairy farming situation.”

He explains that around the same time there was an explosion in the use of synthetic nitrogen fertiliser, which along with irrigation could be used to grow more grass and feed more cows. Just like the gold rushes of earlier days, when word got out, everybody wanted in. According to Stats NZ, the number of cows in Canterbury jumped from 113,000 in 1990 to 1.2 million in 2019.

But, according to Joy, this has come with a cost – intensive dairy farming is polluting our rivers and aquifers, and it’s only getting worse. He says the problem created is now too big for farmers to fix on their own.

“We have to realise we made a big mistake here, and let’s sort it out,” Joy says, and explaining that the major issue with water contamination is nitrates. Cows pee – a lot – and this nitrate-rich urine combines with synthetic fertilisers to dump a whole lot of nitrogen into the soil.

“It just goes straight down, very quickly past the root zones through those gravelly soils and into the layers and layers of aquifers that run out this way,” Joy says of the Canterbury region. For our rivers and lakes, it causes toxic algal blooms which can be harmful to plant, marine and human life.

There’s no better example than Lake Te Waihora/Ellesmere, the catchment at the end of the Plains. It is, as Liz Brown, chair of local Te Taumutu Rūnanga describes it, the sink at the bottom of the drain. “Whatever we do upstream is going to have an impact on what eventually arrives in Waihora,” says Brown.

Local Kevin Rouse, who lives on the lakeshore, recalls catching 30 flounder a day 30 years ago. Now, he’s lucky to get one.

There is also growing concern about the effects of high nitrate levels in drinking water. While New Zealand regulations are 11.3mg/L, a 2018 Danish study found that anything over 1mg/L may be linked with an increased risk of bowel cancer.

Iain Piper of Leeston has been testing his own well out of concern for his family. After his first well tested at around 17mg/L, he had a deeper well drilled, which tested around 11mg/L. Now, $17,000 later, the family uses a reverse osmosis machine to filter their water, which still sits at around 4mg/L.

Joy says for Canterbury to have safe drinking water, farming intensity on the Canterbury plains will need to reduce by 12 to 24 fold. Environment Canterbury councillor Lan Pham is pushing for change with the same urgency. She says farmers have been hit with regulations to try to curb nitrate levels, but the changes constitute a drop in the ocean.

“All that tells me is that we are polluting a little bit less. It doesn’t tell me that we’re actually moving the dial in terms of the magnitude of change required to actually have a functional environment.”

Joy wants Canterbury to consider a scheme which has been applied in the North Island to save lakes Taupo and Rotorua, and one which doesn’t put the onus on farmers to fix the problem. It involves central government paying farmers to de-intensify or transition from dairy.

“It’s not the farmer’s fault,” Joy says. “They’re just doing what they can to stay in business. The change has to be enabled. We have to be able to help farmers get out of the trap that they’re in at the moment.”

John Sunckel, Leeston dairy farmer and Environment Canterbury councillor, agrees that farmers can’t be expected to give up their businesses without some kind of certainty for the future. “What are you asking me to change to?” he says. “What will you give up? Will you give up your house, your car, your retirement fund, your super fund, everything that you own and have strived for, your retirement and walk away from that?”

But with central government support, Sunckel says he’d consider the idea more seriously. “If the government or the people of New Zealand believe that is what they want, then pay me out, and I’ll walk away. But in the interim, don’t just tell me I need to cut cows or do something different, when I have no pathway,” he says.

Lan also wants action from the top. “I would love to see central government actually seizing the power that they hold to shift this dial much further and faster.”

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