It is Not Just About Irrigation

by Dr. Peter Trolove

NZ Federation of Freshwater Anglers executive member



The Environmental Law Initiative ELI has met with success in seeking a judicial review of the Environment Canterbury Regional Council’s (Ecan’s) illegal renewal of the Ashburton Lyndhurst Irrigation (ALI) consents allowing continued leaching of nutrients (nitrate) into groundwater.

While this High Court judgement focused primarily on law and process, environmentalists must be encouraged that ongoing environmental degradation was the central issue for this decision. (S. 107 of the RMA 1991).

Within his judgement Judge Mander reminded Ecan that the RMA has primacy over Ecan’s regional plan.

ELI website:

Reputational damage from Ecan’s “own goals”

The Environment Canterbury Regional Council continues to have a poor record when it comes to meeting its statutory obligations with regard to protecting the environment in accordance with the RMA 1991.

There is irony in a recent post on Ecan’s website 16 November 2023;

This post attempts to explain Ecan’s CEO and Director of Science’s actions in applying to the Environment Court seeking a Declaration that Ecan is not accountable for the Rakaia River NWCO. That Ecan’s role is simply to issue consents and ensure the consents are complied with. 

Subsequently these managers abruptly withdrew their application because, according to these Ecan managers, “all parties agreed with Ecan’s role”.

This post is not accurate. Ecan withdrew its application before the Environment Court could invoke its powers. Subsequently both EDS and F&G made fresh applications to the Environment Court that Ecan is accountable for WCOs.

Ecan’s participation in support of the Ashburton Lyndhurst Irrigation scheme in this recent High Court case shows Ecan is not an independent regulator.

Ecan has a controversial history when it comes to irrigation

Canterbury is a naturally drought prone region. 

Recent central and regional government initiatives have greatly expanded the amount of irrigated land in Canterbury enabling intensive dairying reliant on massive amounts of water for irrigation and milk harvesting, combined with a high use of synthetic nitrogen.   Irrigation has enabled other industrial forms of farming to replace pre-existing environmentally sustainable forms of farming. 

This has compromised the region’s freshwater environments, particularly the health of lowland streams and coastal lagoons and has raised issue of whether the allocation of public water resources to private landowners has resulted in a fair sharing of economic benefits.

In response to a 1998 drought the Ministry of Agriculture and Ministry for the Environment set up a Steering Group of irrigation interests, project managed by a Public Relations firm, to develop the Canterbury Strategic Water Study (CSWS).  While the Canterbury Water Management Strategy (CWMS) was to replace the CSWS with the aim of developing a broader role of a balanced consideration of a water strategy for Canterbury, a core of CWMS Steering Group members had also been involved in one or more of the earlier CSWS processes.

Ecan had lost control of its ability to regulate freshwater use in Canterbury in the “Canterbury Water Wars” while the irrigation proponents were themselves in a weak position due to community divisions in Canterbury, high regulatory risks and high process costs in obtaining RMA consents for community irrigation schemes.

The government intervened in March-April 2010 by sacking Ecan councillors and replacing them with appointed commissioners: removing rights of appeal to the Environment Court on both the NRRP and water conservation orders; and changing the decision criteria for the latter. The vehicle used for this intervention was the Ecan Act (2010). The Act also gave statutory recognition to the Vision and Principles of the (non-notified) CWMS. 

Canterbury Water Management Strategy – a case study in collaborative governance. Guy Salmon, Ecologic Foundation, Report prepared for Ministry of the Environment February 2012.]

The Ecan Act 2010, passed under urgency, was criticised by Professor Phillip Joseph in the June 2010 NZ Law Journal as being constitutionally repugnant, causing the disenfranchisement of the residents of Canterbury and creating a loss of trust in central and regional government. 

The Vision and Principles of CWMS, which became the foundation document for the region’s Land and Water Regional Plan (LWRP) has been successively massaged from giving first priority to the environment and second priority to irrigation, to emphasising “sustainable economic development”.

Over the past decade most of the irrigation objectives of the CWMS have been met while not a single goal or target contained in the CWMS relating to freshwater has been achieved. 

To put it bluntly these aspirational targets have proved to be worthless.



In Transition

Only as recently as November 2019 has Ecan returned to full democracy.

It is apparent that the Council is divided between the longer serving councillors and senior managers retaining a pro irrigation culture, with a fresh crop of mainly urban councillors keen to include the environment.

Of course the recently formed Coalition Government is another confounding factor with Ministers Bishop, Brown, and Jones unilaterally assuming powers normally associated with dictatorships.

Are all New Zealanders about to experience a national version of the Ecan Act?

The Coalition Government has spent its first 100 days unravelling much of the work of the previous government including signalling its intention to review the National Policy Statement for Freshwater Management (NPS FM) standards and extending the period allowed for regional councils to include the August 2020 NPS FM standards into their regional plans out to 2027.

Why is nitrate leaching a concern?

While irrigation has undoubtable boosted Canterbury’s GDP, it has also greatly exacerbated a previously recognized legacy problem due to nitrate leaching through Canterbury’s vulnerable light porous soils into groundwater.

The high use of water plus large amounts of synthetic fertilizer required by large Canterbury dairy farms has measurably increased the tons of nitrate leached into groundwater polluting rural drinking supplies and degrading spring fed streams and coastal lagoons.

The dairy cow herself is the major source of nitrate leaching – a cow urinates 10-12 times a day covering an area of 1.0 to 0.7 square meters on each occasion with the equivalent of 700 to 1000kg of N / hectare. At the high stocking rates enabled by irrigation this equates to around one third of a dairy farm receiving this amount of nitrate loading per annum.

This is why a small reduction in the amount and timing of synthetic urea applications is of limited significance.

While models such as OVERSEER have been the basis for the development of Farm Environment Plans to mitigate nitrate leaching along with “Good Management Practice” (GMP) the hard fact remains that there is presently no proven means to manage nitrate leaching to groundwater.

(OVERSEER is of no use once the nitrate has passed the root zone).

Despite this Ecan continues to enable and protect irrigation objectives while paying lip service to the environmental consequences.

i) Public Health

High nitrate levels in drinking water has been correlated with:

“Blue baby” deaths

Premature birth and shortened gestation

Bowel cancer

Other cancers such as breast and thyroid cancer.

The present Maximum Allowable Value (MAV) for drinking water in NZ is 11.3 mg/L NO3-N, (or 50 mg nitrate). The United States MAV for drinking water is 10.0 mg/L NO3-N.

There is a growing number of peer reviewed studies suggesting the MAV should be at least half this figure.

Two community water supplies in Canterbury have exceeded the MAV in recent years, both are connected to the expansion of dairying.

Up to 10% of rural wells in parts of Canterbury now exceed the MAV for drinking water, requiring users to pay for costly mitigation such as reverse osmosis filters.

Ecan and District Councils consider rural residents are accountable for their own drinking water.

Apart from making Farm Environment Plans part of its Regional Plan, Ecan’s cavalier response has been to pass the nitrate problem off as a legacy issue and to plant trees. (Trees will not mitigate nitrate leaching).

ii) Environmental health

Most freshwater biologists and ecologists accept a “bottom line” of 1 mg/L NO3-N as being a scientifically defensible limit for nitrate in freshwater.

This will largely prevent indirect harm from eutrophication leading to lethal (low) oxygen levels when die off of exuberant plants &/or algae occurs.

Direct nitrate toxicity is poorly researched.

Most published studies involve 96 hour LD 50s. (The levels where 50 % of a given species dies if exposed to a specific concentration of nitrate for 96 hours).

A limited number of studies resulting from hatchery losses have found trout & salmon eggs and fry begin to show observable adverse effects from about 2.5 mg/L NO3-N with losses beginning to occur around 3.5 to 6.5 mg/L depending on the species and other water quality parameters.

This is why there are no longer any juvenile trout in so many of Canterbury’s lowland spring fed rivers and streams.

Why do fish biologists and freshwater ecologists have such a hard time at consent hearings?

As commented on previously, governments and councils take ownership of only one side of the irrigation debate.

It is easy to project the economic benefits of irrigation while it is much harder to quantify the true cost of environmental degradation and the loss of “ecosystem services” which is cynically passed to future generations.

In Canterbury other than the likes of EDS, ELI, and advocates such as the New Zealand Federation of Freshwater Anglers, no other government agency or private party has the political will, power, or vision to take ownership of the problem as a whole.

F&G has made an effort at times and has been missing in action on other occasions. F&G does not seem to display the passion and tenaciousness of their predecessors, New Zealand’s Acclimatization Societies.

Ecan is unashamedly pro irrigation supported by the Canterbury Mayoral Forum and the Mayoral Forum’s non-notified Canterbury Water Management Strategy.

Never Enough Science / Thank goodness for the Court(s)

“The search for scientific perfection in ecosystem management is fundamentally misguided.

As sensible ecologists have frequently warned, ecology and the related biological sciences will never reach the precision of physics and mathematics. The natural science world will never be a matter of formulaic prediction or perfect understanding. The search for impossibly perfect science-based decisions deflects attention from the more important issue of legitimacy. 

One of the strengths of law is that it has never demanded perfection or even truth in the absolute sense, being satisfied with the more attainable role of legitimacy. Although reasonably accurate data, transparency, and reasoned conclusions are necessary components of legitimacy, absolute certainty or precision is not.

All that can be asked of decision makers in the face of incomplete scientific information is that they reach a justifiable decision in light of the available information. 

In the context of natural resource regulation, the key legitimacy question is not whether the variety of judgements that go into regulatory decisions are objectively correct or certain, but whether they are adequately serving legitimately chosen societal goals.

To achieve that, the process of decision making must be appropriately controlled, with adequate support and effective oversight” 

[p 189, National Research Council. 2008. Hydrology, Ecology, and Fishes of the Klamath River Basin. Washington, DC: The National Academies Press.]


Thank you ELI for your good work on this one.

It would help if freshwater ecologists and fish biologists took their place at the “Top Table” that has so far been the preserve of politicians, senior bureaucrats, lawyers and engineers.

This is necessitated by the fact that bureaucrats cannot function with uncertainty, and engineers & hydrologists only think in terms of mathematical limits.

While the Independent Commissioner responsible approving the illegal consents should be held to account for misinterpreting the law, it would be grossly unfair not to include those who approved the pre-existing consents that have allowed ten years of damage to occur to the lower Ashburton River and coastal environment. This a direct consequence of the (repealed) Ecan Act and the living Canterbury Water Management Strategy.

It is an open question whether the massive irrigation development that has occurred in Canterbury, funded by hundreds of millions of tax payer dollars from the $345 million irrigation enhancement fund for the benefit of a select few, was a legitimately chosen societal goal. 

Guy Salmon’s 2012 report for the Ministry of the Environment is one of several similar documents that have evaluated the Canterbury Water Management Strategy and raised the question of democratic legitimacy.  

One area where Salmon was unequivocal was his finding that the (CWMS) process fell short of properly addressing, resolving and integrating the two critical policy issues in public dispute:

  • Whether the extent of the proposed land intensification across Canterbury was consistent with the restoration of healthy ecosystems in lowland streams and coastal lagoons; and
  • Whether the allocation of public water resources to private landowners would result in fair sharing of the economic benefits

Salmon was prescience with his conclusion; “However, there is much evidence that the economic fairness issue is a strongly felt public concern, and it is likely to emerge as an ongoing political issue.”

The High Court Judicial review central to this article confirms the CWMS is failing to restore Canterbury’s lowland rivers and coastal environments.

SQ River Jim 2.jpeg

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2 Responses to It is Not Just About Irrigation

  1. B. Cowley says:

    This is a very good revealing of the tragic situation caused through utter failure of politicians and staff-all public servants. It’s not only aquatic ecosystem that has suffered but also human health, e.g cancer. Do politicians at national and local level, especially ECan, have a conscience? It seems not.
    Significantly the bowel cancer rates for South Canterbury are abnormally high.

  2. Robert Read says:

    Thankyou for such a concise document explaining how our waterways and acquifers became so contaminated.
    Corporate farms funnelling profit overseas at the detriment of our land should be outlawed and New Zealand Super Fund forced to move out of dairying.

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