The Otago Regional Council's "command and control" approach to water quality standards is "unenlightened", environmental scientist Peter Callander says.
"Rather, it is an approach that says ORC knows what is best for you, and you will do as you are told - hardly the basis for a constructive working relationship," he told the 6A water plan hearing panel in Dunedin yesterday.
Mr Callander, speaking for Dairy Holdings Ltd (DHL) which owns five dairy properties in North Otago and five in South Otago, said the nitrogen limits proposed potentially had significant implications for land-use activities, but the change that would be required, such as from border dyke to spray irrigation, might not result in any meaningful improvement to water quality.
DHL chief executive Colin Glass said his company was concerned limits had been set without regard for water quality levels within the catchment or an understanding of the achievability of nutrient limits using Overseer version 6.
The proposed plan change "will not be attainable by DHL's Waitaki farms even though the catchment is regarded as having acceptable water quality standards".
DHL counsel Ben Williams said the proposals were contrary to the obligations in the National Policy Statement on Freshwater Management and the Resource Management Act.
Franklin Rural Management Ltd managing director Derek Hopkins, on behalf of Dairy Farms Partnership owners of four farms in Ranfurly and Patearoa, said there needed to be greater flexibility to implement the practical changes required to meet discharge limits in a way that best met individual land management regimes.
"We need to know from day to day whether we are compliant and what steps we need to take to ensure this."
The wide variation in Otago's soil types, land management systems, and rainfall were "potential major impacts" that needed research and clarification as to their effect on the plan change.
The proposal's reliance on the Overseer programme was a concern as its science did not seem that robust, Mr Hopkins said.
Oceana Gold counsel Marie Baker-Galloway said that while 6A was aimed at agricultural run-off, Oceana was concerned at the precedent implications of the proposals, especially the removal of the use of reasonable mixing zones.
"Without the security of discharges continuing as they currently are, the Macrae's gold mine may be compromised to the extent the mine would be unable to operate."
Instead, the council should consider retaining reasonable mixing as an alternative so an appropriate monitoring and compliance regime could be established on a case by case basis.
"To remove all reference to reasonable mixing is, in my opinion, unprecedented and untested ... and should not be embarked upon without a practical alternative ...".
