More intensive dairy farming means declining water quality, and Massey University ecologist Mike Joy says that's something that should concern all New Zealanders.
The findings of the just-released report Water quality in New Zealand: Land use and nutrient pollution, by the Parliamentary Commissioner for the Environment, should serve as a call to action, Joy says.
Changes in the way New Zealanders use land are harming water quality and we need to do something about it, according to the commissioner, Dr Jan Wright.
She says there has been a shift from sheep and beef farming to dairying and that has to mean more pollution - an increase in leaching of nitrogen and phosphorus into waterways which, in turn, causes excessive growth of weeds and algae, choking the waterways.
Joy says it was a good piece of science, carried out by an independent research team.
"There are only 20 people in that office - you take some out for administration, some are on holiday - there aren't many of them researching issues and they do a great job."
He says there are not many independent researchers left and many people rely on money from farming industries.
"In the future, there will be more cows on farms, and more dairy farms. A sheep and beef farm leaches about 5 kilograms per hectare a year of nitrogen. A dairy farm leaches 130kg per hectare a year of nitrogen."
One kilogram of nitrogen makes 88,500 litres of pure water undrinkable, Joy says.
The nitrogen fertiliser most farmers put on their land is not the main issue - most of the nitrogen comes from cow urine. It gets into the underground water and makes its way into waterways.
If cows stand on a feed pad and the urine is collected and spread, the amount of nitrogen leached is halved.
Joy says farmers want to believe the science on leaching is not clear and often blame sewage outfall and point source discharge.
"The jury is not out at all. The science is clear. Five per cent comes from independent sources (such as town or city sewage) and 95 per cent comes from farms."
Drawing on modelling of land use and nutrient runoff, the water quality report paints a grim picture of the future, predicting that loss of nitrogen and phosphorus into waterways will continue to increase - even under "optimistic" assumptions. The growth of dairy farms will outstrip mitigation, even if it is as successful as farmers hope.
Fonterra chief executive Theo Spierings says Fonterra does need to grow its milk supply, but it has to be a case of more milk from the existing number of cows, rather than more animals. He says housed cows are an option.
"Going forward, when we want to grow dairy, we will need to do it in a sustainable way."
Spierings says Fonterra wants to look forward and it has a 10-year growth plan, which it has presented to the Government.
Southland is still growing in farm conversions and cow numbers, and farmers there are looking for solutions in sustainability, he says. A one-size-fits-all approach to sustainability would not be suitable.
At last week's annual meeting, Spierings spoke about Wright's water quality report. He said the report was "in the past and looking backwards". It looked at samples and situations which Fonterra had already said a few years ago were not good enough.
But that isn't how the water quality scientists see it - rather, the commissioner's report looks forward, with modelling, Joy says.
Dairying has a cumulative effect, he says.
"It's like driving a car. You think ‘I'm not adding to the global problem,' but when you add the impact of all cars it is having an effect.
"Farmers look at themselves - not the whole industry."
Wright says she is pleased that fresh water policy is very much on the Government's agenda, with the recent release of a discussion paper on setting "bottom lines" for water quality.
But Joy says the Government's water discussion document is a "giant leap backwards".
Director of the Waterways Centre for Freshwater Management at the University of Canterbury & Lincoln University, Professor Jenny Webster-Brown, says the PCE's report sends a strong message - "We cannot expect to achieve the water quality goals . . . in a regime of increased dairy production".
Webster-Brown says the predicted environmental outcome of allowing immediate economic gain to continue to dictate our use of land should be taken seriously.
Massey University Professor of Agriculture and Environment Russell Death says: "As the son of a retired dairy farmer and a country lad at heart, I would love to see the win-win for the economy."
But he says the PCE report clearly illustrates what many scientists and economists already know: if New Zealand continues with increasing dairy intensification, without some drastic changes in farming methods, the most likely outcome is lose-lose.
"Many of our waterways are already badly degraded, agriculture creates pollutants and thus increasing agriculture even with the best mitigation practices - none of which are even close to perfect - will still result in more pollutants entering our waterways.
More pollutants, lower water quality - it's not rocket science."
- Manawatu Standard
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