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Southland estuaries, like the New River Estuary, pictured, need less nutrients discharging into them for their protection, scientists say.
A Federated Farmers life member believes Environment Southland is misinterpreting science to paint a “doom and gloom” picture of the province’s water quality.
However, Environment Southland says its science has been arrived at by using published and peer-reviewed methodologies.
Doug Fraser raised his concerns at an Environment Southland meeting this month.
He questioned the science being used by Environment Southland to inform its limit-setting process for Plan Change Tautahi.
Plan Change Tautahi aims to provide a practical plan to provide for the health of Southland’s water bodies, and will limit the amount of contaminants such as nitrogen which can be discharged into waterways.
The process aims to give individual farms and businesses clarity about how much they may need to reduce contamination, and over what time period.
Speaking at the meeting, Fraser said he looked at a review panel’s recommendations in regard to the limit setting, which said the health of many water bodies in Southland did not meet community expectations.
The panel said there was a high degree of uncertainty surrounding the model predictions, and it was mindful the data was sparse and the assumptions of any instantaneous links between land use and water quality were likely to be incorrect, Fraser said.
The panel also indicated the models didn’t support what was being found in the river testing, he added.
Robyn Edie/Stuff
Doug Fraser says nitrogen monitoring on his Aparima farm shows nitrogen levels have been low for years.
Citing further reason for concern, he noted draft recommendations from Environment Southland saying a 64% reduction in the nitrogen load was required in the Aparima catchment.
This was despite nitrogen monitoring on his own Aparima farm showing nitrogen levels to be very low for years, he said.
Cr Maurice Rodway, at the council meeting, said he had confidence in what its scientists were saying because their work had been extensively peer-reviewed.
“Overall, what they are saying is we do have to make quite substantial reductions in our nutrient losses to protect things such as estuaries.”
Fraser asked Rodway if the review reports had raised any red flags with him.
“There’s certainly some uncertainties there, but overall I have confidence that … the experts are sending us in the right direction,” Rodway replied.
Environment Southland chairman Nicol Horrell said the council would be talking to the community when it started the Plan Change Tautahi process.
Environment Southland’s science manager Rachael Millar, in response to questions after the meeting, said its proposed contaminant reductions to achieve freshwater and estuary improvements were arrived at by using published and peer-reviewed methodologies.
An independent panel involving scientists found that the models used to estimate contaminant loads were conceptually sound and appropriate for the purpose, Millar said.
Uncertainties with scientific information informing limit-setting decisions were inevitable and needed to be taken into account by decision makers, she said.
“In this instance, this will occur as part of the limit-setting plan change process.”
Millar said individual monitoring sites may not show an issue for a particular contaminant at a specific time, so it was important to consider a catchment as a whole and the contamination build-up over time.
