Hawke's Bay Regional Council staff believe a low water nitrogen limit set for the Tukituki catchment by a board of inquiry is "not based on robust science" but should not be challenged through the courts because an appeal against the board's decision is unlikely to succeed.

The board of inquiry imposed the dissolved inorganic nitrogen limit as part of an environmental management plan - known as Plan Change 6 - in a decision released late last month. The board also approved consents for the council to build the Ruataniwha dam and water storage scheme.

The impact of the plan change decision - in terms of both the implications for land use in the catchment and the viability of the irrigation scheme - will be discussed at a meeting of the council's corporate and strategic committee tomorrow.

In a report prepared for the meeting, the council's group manager of strategic development, Helen Codlin, recommends against taking legal action over the board's decision. "Staff remain of the view that the DIN (dissolved organic nitrogen) limit of 0.8mg/L is not based on robust science applicable in the Tukituki catchment," she says.


"Preliminary legal advice is that an appeal on the DIN limit would be unlikely to succeed (appeals are limited to points of law) and given the availability of a workable route for existing farms going forward, staff do not recommend an appeal on this point."

The "workable route" open to the council is based on the board of inquiry determining that the limits and targets in the plan change can be reviewed over time "if robust monitoring and science demonstrates that any of those limits and targets are either too lax or too strict".

The board of inquiry's decision requires 1062 farms in the catchment to complete environmental management plans by June 2018, at an estimated cost of between $3000 and $5000 each.

The council "will be working through the business process for developing these and managing the compliance and consent requirements associated with them in order to assess additional staff requirements," Ms Codlin's report says.

Meanwhile, the directors of the council's investment company met yesterday to discuss the implications of the board of inquiry's decision on the dam project but will not discuss the issue until they brief the council at tomorrow's meeting.

The council voted last month to invest up to $80 million in the Ruataniwha scheme provided a number of conditions are met, including its investment arm, Hawke's Bay Regional Investment Company (HBRIC), being able to convince irrigators in the catchment to sign up to take a set minimum amount of water from the scheme.

HBRIC's ability to convince farmers and growers in Central Hawke's Bay to sign water uptake contracts will be dependent on how restrictive irrigators believe Plan Change 6 will be on their ability to increase productivity.