Law change leaves polluters protected after mega-irrigation ruling
Wednesday, 3 September 2025
A controversial mega-irrigation scheme has kept its consent to pollute, even though the High Court found a regional council broke the law in granting it.
The Environmental Law Initiative largely failed in its judicial review challenging Environment Canterbury’s (ECan) decision to grant a nitrogen discharge consent to the Mayfield Hinds Valletta (MHV) irrigation scheme.
Justice Mander ruled ECan breached section 107 of the Resource Management Act (RMA) when it granted the consent to discharge across 138,000 hectares between the Ashburton/Hakatere and Rangitata rivers.
The council also failed to properly apply coastal policy provisions.
Despite that, the consent will remain in place. The judge said recent Government amendments to the RMA – introduced after pressure from farming lobby groups – had weakened the bottom-line protections of the clause, giving the court little scope to cancel the approval.
ELI also argued ECan failed to account for risks to drinking water supplies.
But the judge rejected that claim, even though ECan’s own modelling shows hundreds of private bores in the command area are at risk of breaching safe nitrate levels.
Anna Sintenie, a senior researcher at ELI, said the ruling showed how water protections were being undermined.
“We are alarmed that water quality protections are being weakened at every turn,” she said. “These reactive changes to the RMA mean short-term profit for a few, but a long-term loss for everyone.”
ELI is considering whether to appeal.
Last year, the same group won a landmark case against another Canterbury irrigation scheme, Ashburton Lyndhurst Irrigation Ltd (ALIL).
The High Court quashed that consent after finding ECan had unlawfully approved nitrogen discharges over 177,000 hectares between the Ashburton/Hakatere and Rakaia rivers.
The decision was seen as a breakthrough in enforcing environmental “bottom lines” written into the 1991 RMA, which prohibit discharges likely to have significant adverse effects on aquatic life.
But farming and irrigation lobby groups warned it posed an “existential threat” to dairying, arguing it would force many farmers to seek resource consents simply to operate.
Within weeks, the Government amended the RMA under urgency, creating new clauses that allow councils to permit otherwise prohibited discharges in catchments already degraded by pollution.
Canterbury’s plains are among the most intensively farmed areas in the country, and nitrate contamination of drinking water is a growing public health concern. Elevated nitrate levels have been linked to higher risks of colorectal cancer.
MHV Water chair Cole Groves said the farmer cooperative is pleased with the result of the High Court's decision.
“This will enable MHV to continue working to reduce nutrient discharges from its shareholding farms while also supporting and implementing a range of environmental projects and initiatives that will improve water quality and biodiversity in the catchment,” he said, in a statement.
“MHV is grateful for its shareholders' support and confidence through this period and the constructive approach of Environment Canterbury.”
ECan chief executive Stefanie Rixecker said the council was leased with the decision to dismiss the application for judicial review.
“The Court confirmed council’s long-held position that Canterbury Regional Council (Environment Canterbury) decisions on resource consent applications are irrevocable final decisions that cannot be substantively re-examined by us.
“Because there is an appeal period running, it is not appropriate to comment further at this stage.”