Environmental groups have criticised IrrigationNZ for making "misleading" comments over the state of New Zealand's rivers.
The Environmental Defence Society and Forest & Bird were commenting on a map released by IrrigationNZ showing the nutrient levels in 622 rivers.
IrrigationNZ commisioned government agency Niwa to produce the map, which it said showed that 10 per cent of rivers recorded nitrogen concentrations above the limit set by the Tukituki Board of Inquiry.
The groups said the Niwa report mapped rivers where the median nitrogen concentration exceeded 0.8mg per litre.
"However, the nitrogen limit set by the board of inquiry will apply to the average nitrogen concentration. In practice, this is a limit that will be met more easily.
"Whether Irrigation NZ likes it or not, the reality is that irrigation schemes should only go ahead if they can operate within acceptable environmental limits. To do otherwise would be reckless and irresponsible."
The society and Forest & Bird said that, having lost the argument in the board of inquiry, it appeared that Irrigation NZ and others were attempting to put pressure on the board by relitigating the issues in the media.
They also attacked Prime Minister John Key for his comments on the process.
"It is highly inappropriate for the prime minister to even suggest the Government may intervene in this issue.
"Given that the board of inquiry was appointed directly by the Government, the prime minister's comments could be seen to be directed at influencing the board to change its position. This would be unlawful.
"The Land and Water Forum brought together industry (including IrrigationNZ), environmental, recreational, iwi and other organisations to develop a shared vision for freshwater and land management. It concluded that land use intensification has to be subject to water quality limits that protect ecosystem health," the groups said. "We continue to agree with this consensus view.
"On the basis of more than 28,000 pages of material, the board concluded that a limit of 0.8mg/L was the highest nitrogen concentration that would protect ecosystem health while providing for sustainable agricultural land use."
- Waikato Times