Self-criticism from within Canterbury’s regional council, contained in an unpublished report on the Rakaia River, has been bolstered by evidence filed in the Environment Court.

The council, ECan, is asking the court to make a series of declarations, principally about whether it is legally obliged to monitor and enforce the Rakaia’s water conservation order (WCO) – likened by environmentalists to national park status for rivers.

A central issue in the case is management of Lake Coleridge by NZX-listed Manawa Energy, formerly known as Trustpower.

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After the WCO was amended in 2013, the company, which operates a hydro-electric power station at the lake, started sending water down the Rakaia River to be diverted and used by irrigators, including the South Island’s largest irrigation company, Central Plains Water.

The aforementioned unpublished report, leaked to Newsroom in 2021, said there was evidence the WCO was being breached, and consent limits for water-takes were occasionally exceeded.

(Starving the river of water can be detrimental to fish, birds, insects and other creatures, as well as affecting human activities like jetboating, kayaking and fishing.)

Wilco Terink, the report’s author, a senior hydrological scientist and data analyst, left ECan after his bosses wanted to withhold contentious findings.

Alongside ECan’s application for Environment Court declarations, the regional council provided an affidavit from Richard Purdon, its principal consents planner. This past Friday, the court released the affidavit to Newsroom.

Purdon’s evidence sets out the council’s functions under the Resource Management Act, noting one of the most critical is compliance monitoring and enforcement. ECan’s approach to managing compliance is “risk-based”.

What that means in practice, Purdon says, is its 25-or-so warranted officers actively monitor between 2000 and 4000 of the province’s 24,000 consents in a given year.

“Historically there has been very little dedicated water-take compliance activity undertaken on the Rakaia River, beyond that carried out in the ordinary course of compliance monitoring more generally.”

Purdon did state, however, he was part of a recently formed Rakaia team charged with checking compliance for the river’s 90 water-take consents.

ECan said last year those compliance checks, paired with “further refined analysis” by its surface water science team, indicated “the potential for non-compliance” – lending credence to the Terink report’s findings.

The report also highlighted ECan’s inability to effectively monitor Rakaia consents, calling it a major concern. The regulator didn’t know, in real-time, how much water is entering or leaving Lake Coleridge, or the lake’s level.

“The council’s ability to monitor Manawa Energy’s actions in this regard is limited.”
– Richard Purdon affidavit

An already opaque situation was made worse, potentially, when, in 2015, Trustpower, as it was then, adopted a new regime for water accounting at the lake, “storing” water for irrigation below its minimum operating level.

Worried this might breach the WCO, ECan urged, through its lawyers, that Trustpower seek an Environment Court declaration. No declaration was sought and, as we know from Purdon’s evidence, there were few checks to see its effect.

Problems were only picked up, seemingly, when Terink crunched the numbers.

His report said: “It can be concluded that calculations behind this concept do not meet the conditions set out in the [WCO] amendment.” There had also been a “substantial” increase in diverted water into Lake Coleridge from the Wilberforce River which, Terink said, potentially breached the consented limit.

Purdon’s affidavit said the WCO amendments in 2013 hadn’t prompted Manawa Energy to get new consents – for example, for the calculation and use of so-called stored water. Nor had it sought consents for its ambitious ‘Lake Coleridge Project’, or to establish its “enhancement” and “hapūa” funds.

“As a result, the council’s ability to monitor Manawa Energy’s actions in this regard is limited.”

Manawa’s calculations for stored water, and how much is being ordered and released to irrigators – crucial to its compliance with the WCO – is contained in its online irrigation management system.

“This information is not publicly available or accessible,” Purdon notes. Access is “controlled by Manawa Energy”, and only registered users “and some CRC [Canterbury Regional Council] officers”, can access it.

Trustpower, now known as Manawa Energy, stores irrigation water in Lake Coleridge and releases it down the Rakaia River. Photo: Francis Vallance/Flickr/Creative Commons

Clause 9A(3) of the WCO requires the operator of Coleridge’s power scheme to keep accurate water records, including calculations of stored water.

However, because the clause isn’t contained in a resource consent, Purdon said, it is “not actively monitored by the council’s compliance team”.

Newsroom put the matters outlined by Purdon to the parties to the Environment Court proceedings. In particular, we said we’d welcome comment about Manawa not seeking a court declaration when asked by ECan, and not seeking further consents, as well as ECan’s ability or willingness to monitor and enforce compliance.

Paul Ford, Manawa’s head of corporate relations, says via email the company is confident it holds all the consents needed to run its business, and it operates within the parameters and conditions of those consents.

“Monitoring downstream consents is outside our responsibility and is a question better directed at the consenting authority. We are looking forward to the court providing additional clarity on this in due course.”

The chief executives of the North Canterbury Fish and Game Council and Environmental Defence Society – Rasmus Gabrielsson and Gary Taylor, respectively – issued the same emailed statement, that they’re “pleased that progress is finally being made on clarifying these issues, but is unable to make any more detailed comment as the matter is now before the court”.

Meanwhile, Stefanie Rixecker, ECan’s chief executive, says: “As the matter is now before the Environment Court, it is not appropriate for the council to respond to your specific questions regarding the declaratory proceedings or Richard Purdon’s affidavit.”

An intriguing exchange

Appended to Purdon’s affidavit are the letters sent between the lawyers for Trustpower and ECan about the stored water concept.

In March 2014, Trustpower’s lawyer Bal Matheson, a partner of the firm Russell McVeagh, outlined the rising demand for Rakaia water, and how, because of the WCO’s cap on water-takes, and the river now being “effectively fully allocated”, the reliability of water-take permits was being affected.

Coleridge held an estimated 4 billion cubic metres of water, while a “mere fraction”, of about 100 million cubic metres, sat within the lake’s usual operating range. (To give an impression of scale, 100 million cubic metres is about the same capacity as Auckland’s 10 drinking water dams.) 

The issue, according to Matheson, was about 450 million cubic metres of water entered the lake that “would qualify as stored water” – meaning the “productive use” of about 350 million cubic metres would “potentially be forgone in any year”.

(For example, if the lake was “full”, because the level was at the top of its operating range, all water flowing in would have to be immediately discharged down the Rakaia, even if there was no irrigation demand.)

“The opportunity would therefore be lost to store this water, and release it during low flows.”

One solution would be to build additional storage, like a reservoir dam, but that could potentially cost hundreds of millions of dollars.

Trustpower’s alternative solution was to allow “stored water” to be banked beneath Coleridge’s consented operating range, expanding the “theoretical storage capacity” of the lake to more than 300 million cubic metres.

“Trustpower can continuously classify and reclassify water within the top 3-4 metres as either normal water or stored water, depending upon what type of water is required.”

There would be “no additional environmental effects”, Matheson maintained, and Coleridge would remain within its consented operating range. No variations to consents or to the WCO were needed.

Opponents may argue more stored water meant more irrigation and, therefore, more groundwater effects, Matheson posited.

“The appropriate response to this is that some form of storage was always going to be provided, and the alternative to Trustpower’s proposal is that it would occur in a distributed manner with, inevitably, much greater adverse environmental effects.”

(Arguments like this were never made, it seems, because Trustpower and ECan decided to keep the new regime from the public.)

ECan’s response to Matheson, written in August 2014 by its lawyers Wynn Williams, began with an endorsement.

“At the outset, we record that the council is supportive, in principle, of the revised Lake Coleridge Project,” wrote Wynn Williams partner Philip Maw. “It is consistent with the council’s vision as to how freshwater is to be managed in the Canterbury region, and it is consistent with the Canterbury Water Management Strategy.”

On the face of it, the WCO didn’t restrict Trustpower’s “full storage” plan, Maw wrote, but ECan couldn’t preclude the “risk of a third-party challenge” – the implication being ECan wouldn’t challenge the proposal itself.

“We consider that a challenge could be framed on the basis that the revised Lake Coleridge Project (and the proposal to reclassify normal water as stored water) is different to the basis on which the amendment to the Rakaia WCO was granted.”

The letter then hedges.

On one hand, Trustpower’s information showed a difference between the lake levels and river flows modelled and presented at the WCO amendment hearing. On the other, however, the levels and flows were still within the consented operating range, and didn’t appear contrary to the wording of the amended WCO.  

“It is difficult to say, based on the information that Trustpower has provided, whether the effects will be better or worse than the effects considered during the WCO amendment hearing,” Maw wrote.

“There has been no independent testing of that information as no application has yet been filed. As such, we cannot say with any degree of certainty that there is no basis for a third party to challenge the revised Lake Coleridge Project.”

Purdon’s affidavit to the Environment Court, dated February 14, said the regional council advised Trustpower if it wanted to be certain its proposal was consistent with the WCO an Environment Court declaration should be sought.

The actual wording in the Wynn Williams letter seems more legalistic and passive: “If Trustpower requires a high degree of certainty in relation to the revised Lake Coleridge Project, the council considers that it would be appropriate for Trustpower to seek declarations in the Environment Court that no further amendment to the WCO is required.”

As we now know, the “full storage” proposal was implemented by Trustpower the following year, without an approach to the court.

The fact a declaration has now been sought, some eight years later, by ECan no less, begs the question: When it was clear Trustpower wasn’t going to the Environment Court, why didn’t the regional council file its own application to be sure the Rakaia remained protected?

ECan wants the court to declare that, under the amended WCO: water can be stored below the lake’s minimum operating range; a maximum volume of stored water isn’t prescribed; and stored water isn’t required to be stored separately from other lake water.

In a logical sense, these matters couldn’t have been anticipated by the hearing panel considering the amendment more than a decade ago, as they were raised two years later.

Maw’s 2015 letter might muddy the waters for Manawa, as it says the river flows and lake levels under the new regime are different to those modelled in the 2013 amendment, and, therefore, the effects are unknown.

It will be interesting to see if additional declarations, sought from the court by Environmental Defence Society and Fish & Game, call for fresh evidence to ensure the WCO is being adhered to.

The only comprehensive analysis to date on the effects of enlarging the amount of stored water at Lake Coleridge appears to be Terink’s work, which, let’s remember, found the Rakaia was “being impeded and manipulated beyond what was anticipated” by the WCO.

The Environment Court has put ECan’s application on a priority track. A judicial conference is expected to be held some time next month.

David Williams is Newsroom's environment editor, South Island correspondent and investigative writer.

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