Ministry opposes farmer’s plan

Southland has higher rates of pathogenic diseases than New Zealand as a whole, it noted. A stream called Bog Burn, which began on the de Wolde’s farm and was hydraulically connected to the groundwater, had very poor water quality that was meaningfully degrading.

Another group opposing the application was Fish & Game, which said the area’s poor water quality had led to the collapse of a local trout fishery.

Under New Zealand law, the maximum allowable value for nitrate concentrations in drinking water is 11.3mg/l. Water suppliers are effectively put on a watch list when levels reach half that, and require more regular testing.

The average nitrate concentration in bores around the farm was 9.5mg/l, according to Public Health South, and average results in individual bores had gone as high as 15.8mg/l, well above the maximum allowed.

Current nitrate levels in the school’s bore were not yet available, the ministry said.

Data from the bores closest to the school were seven years out of date, but showed nitrate concentrations were well within the health standards, with no apparent trend.

High nitrate levels are a health concern because it can lead to blue baby syndrome, which can be fatal to infants.

There have been no recorded cases of the blue baby syndrome in New Zealand in recent times. Part of the dispute concerns Overseer that model a farm’s nutrient output.

The consent application, citing Overseer, said the farm’s nitrogen load would reduce with more cows, because of other mitigation measures.

Overseer has been controversial, in part because of concerns about its accuracy and the inherent assumptions made in the modelling that may not reflect reality.

Critics include both farmers and scientists, who have said it is too inaccurate to use as a regulatory tool - its margin of error can be as high as 30 per cent.

Overseer also cannot predict impacts on water quality.

In its submission, Public Health South said Overseer ‘‘does not apply well’’ in this situation, because of the area’s cracked soils.

Fish & Game also raised issue with the use of Overseer in this case.

For Abe de Wolde, the Overseer results were the best assurance he could give.

‘‘Overseer is the only game in town ... if Overseer is not acceptable, please tell us what is.’’