High Court confirms ECan’s nitrate pollution rule was made in error
The High Court has found that Environment Canterbury (ECan) made an error of law when it allowed nitrate discharges from farming as a region-wide permitted activity in its regional plan.
In a judgment dated 22 December, Justice Mander found that ECan failed to properly consider and apply section 70 of the Resource Management Act when it included Rule 5.63, which allowed nutrient discharges in the Canterbury Land & Water Regional Plan.
ECan’s rule cemented the conditions for ongoing intensive farming even as nitrate pollution was already mounting.
ELI Director, Research and Legal, Dr Matt Hall, says the judgment has confirmed ECan’s rule‑making fell short of the law and goes to the heart of Canterbury’s current nitrate crisis.
“ECan's failure to properly apply the law to protect freshwater concerns every Cantabrian working out whether their water is safe to drink or swim in.
“Even though the rule was made 12 years ago, it remains in force and it is central to the nitrate crisis people across Canterbury are experiencing today.
Dr Hall says that is an important development - even if ELI did not win the case overall because the Court found ECan had erred in a core legal obligation regarding the limits to the amount of pollution that it could allow.
By permitting nitrogen discharges without adequate evidence that they would not breach minimum pollution standards under the RMA, the rule removed a key safeguard. It effectively green‑lit further intensive farming in catchments already under stress.
This locked in higher pollution loads and is making freshwater restoration harder for communities and ecosystems.
Earlier this year, Environment Canterbury declared a nitrate emergency, with over 60% of monitored wells showing rising nitrate contamination.
In two other significant cases brought by ELI, the Court has ruled that ECan unlawfully consented discharges by improperly applying key parts of the RMA, pertaining to minimum standards for freshwater quality.
In this case, ECan relied on section 83 of the RMA, to say that once a regional plan becomes operative, it cannot be challenged except through the Act’s strict, time‑limited enforcement pathway. The Court agreed that the provision applied in this case holding that although ECan had erred, the judicial review was barred because the plan became operative a decade ago. ELI argued that s83 should not extend to substantive legal errors where preconditions to rule-making had not been met, but the Court found otherwise.
Despite this, Dr Hall says “this case creates the opportunity to move forward in a different way.
“There is a clear public interest in ensuring Canterbury’s freshwater is protected by evidence‑based, precautionary decisions that put people and ecosystems first.”
Dr Hall says that it will also take a change in political priorities, away from vested interests, to fix Canterbury’s nitrate crisis.
Capacity for 25,000 extra dairy cows has been added in Canterbury this year.
“The Government has now proposed to remove statutory limits to pollution entirely and plans to make its own non-statutory limits.
“It’s weakening limits– when it is the polluting activities we need to change.
“We need to see law changes that strengthen protection for freshwater ecosystems, not undermine them,” says Dr Hall.
Further detail:
Rule 5.63 (Incidental Nutrient Discharges) was introduced through the 2012–2013 plan process, permitting diffuse discharges associated with farming where the land use was authorised, and applied region‑wide until later sub‑regional chapters displaced it in several degraded catchments.
The Court found ECan’s hearing record did not demonstrate the Council was “satisfied” as the law requires - or had sufficient evidence - to conclude certain severe effects, including significant adverse effects on aquatic life, were not likely to arise as a result of being allowed under rule 5.63.
The Court found ECan did not adequately demonstrate it was satisfied the rule would avoid the adverse effects listed in s70, including “any significant adverse effects on aquatic life”. The decision‑making record, it found, was equivocal and lacked the evidence required for such a rule.
Judgment delivered: 22 December 2025, Christchurch High Court; Mander J
In August 2025, Parliament amended s70 RMA so councils can now make certain discharges permitted even where significant adverse effects on aquatic life already exist, provided standards are set and effects reduce over a period of up to 10 years. The amendment also removed the requirement that discharges do not give rise to “floatable or suspended materials” from s70(1)(c).
The judgment underscores that “be satisfied” is the strongest decisional verb in the RMA, demanding clear, recorded reasons and adequate evidence before permitting discharges. That principle continues to shape how councils must justify rules, notwithstanding the amendment’s carve‑outs.
The Government’s change allows permitted discharges in already polluted waterways if plans reduce effects within 10 years, a policy contested by many because it risks normalising harm rather than preventing it. Today’s decision shows why stronger, transparent evidence remains vital, especially where cumulative effects are entrenched.
The Government’s proposed RMA reforms as drafted would entirely remove the statutory minimum standards for freshwater that were in question in this case. In full, these are that discharges do not give rise to:
the production of conspicuous oil or grease films, or scums or foams:
any conspicuous change in the colour or visual clarity:
any emission of objectionable odour:
the rendering of fresh water unsuitable for consumption by farm animals:
any significant adverse effects on aquatic life.