The Primary Industries Ministry was using "extreme scenarios" when working out the cost to farmers of the One Plan court ruling, according to emails obtained by The Dominion Post.
The emails reveal concerns raised by Horizons regional council after Federated Farmers spoke publicly about leaked memos showing that farmers' costs could rise by 22 per cent to 43 per cent if the ruling was implemented.
The figures were said to have come from a Landcare Research report commissioned by the ministry.
Horizons chairman Bruce Gordon raised his concerns with Landcare Research chief executive Richard Gordon this month. Richard Gordon sent an email to the ministry's deputy director-general of policy, Paul Stocks, to advise him that none of eight scenarios considered were the same as the court ruling's.
The scenarios resulting in 22 per cent to 43 per cent cuts to profit were "extreme" and "actually bear little similarity to the One Plan", Richard Gordon said. The scenario most similar to the One Plan would have an impact on profitability of less than 1 per cent.
He received a response from the ministry's director of resource policy, Mike Jebsen, who said the scenario mentioned in the memos was "in our view most closely matched the Environment Court direction".
Asked about Landcare's email yesterday, Mr Jebsen said the 22 to 43 per cent figures were the best indication of likely impact.
In September, the court, having heard from five economists from Fonterra, Horticulture NZ, Fish & Game and two from Horizons, concluded the effect on farmers would be an average of 5 per cent of annual expenses.
The court concluded the region had "urgent water quality issues that require immediate action" and failure to try to reverse the decline would be "inexcusable".
Federated farmers and Horticulture NZ appealed against the decision.
The One Plan as originally notified by Horizons included a regulatory regime based on the type of land and soil on a farm (land use capability) and limiting nitrogen leaching (among other things).
A commissioners' hearing removed the LUC and limits on nitrogen leaching for existing dairy farming but retained the approach for conversions.
The commissioners' decision was the subject of an appeal by 20 parties, some of which were unhappy with the removal of LUC.
The Environment Court ruled the LUC and nitrogen leaching limits needed to be brought back into the plan for both existing farming activities and conversions, to provide certainty and equity.
They are now included in the plan, which has been redrafted and is back before the court.
- The Dominion Post
Is it time for authorities to introduce tougher penalties for poaching?Related story: Booby traps for poachers cost farmers