How did two weed control operations on public conservation land go so wrong? David Williams reports

The effects of the herbicide spraying becomes obvious just past the old, corrugated-iron musterers’ hut, with its tack shed and veranda.

Scattered among grasses at the southern edge of Lake Emma in Canterbury’s Hakatere Conservation Park lie dead exotic Scotch broom plants, while, nearby, the tougher sweet brier is re-sprouting.

But as Canterbury Regional Council ecologist Philip Grove and his colleague Mike Marr, a resource management investigator, pick their way along the 500-metre-long sprayed area, there’s evidence of what Grove calls “non-target spray damage” to native shrubs, matagouri and Coprosma propinqua. (According to documentation, there was both aerial and ground spraying.)

Further on “it appeared that native shrubs were the target of spraying”, according to Grove’s notes from the visit to the Hakatere – around the Ashburton Lakes district, between the Rakaia and Rangitata Rivers – on November 25 last year.

The lakeside hut is visible from the spray damage. Photo: ECan

In one area, hundreds of native plants have been sprayed and killed with no woody weeds nearby. “In fact, lower down the slope from sprayed natives were number of healthy, unsprayed Scotch broom,” Grove writes.

The spraying is also patchy. In some places, bracken and spray-resistant species are only “lightly scorched”. In others, the application is so concentrated that sweet brier and natives alike are killed.

“It really did appear that the operator had ‘gone rogue’,” Grove writes. “And by the end of the run (at the northern end of the spray affected area) was simply spraying any woody vegetation and bracken within range, and that exotic Scotch broom and brier shrubs were no longer the target.”

Weed control is important on conservation land, lest exotic species take over or dramatically alter the character of landscapes or ecosystems. But care must be taken to ensure the protection of native plants and habitats.

Large areas of sprayed-off native vegetation. Photo: ECan

(This is quite different from the recent tension within the department between its obligations to tourists and nature, which led to trees being felled in a national park to protect trampers, and a millions-of-years-old rock overhang being blasted for the same reason.)

ECan’s investigation at Lake Emma was prompted by a routine visit by Department of Conservation staff last September.

They were so concerned by the spraying – and its proximity to water – the local operations manager Duncan Toogood inspected the damage personally and reported it to the regional council’s compliance team.

It turns out it wasn’t the only errant spraying incident in Mid Canterbury, and the same DoC staff member was involved in both.

“The environmental impact of such an activity could be significant and if a similar offence were to reoccur in the future it is likely that enforcement action would be taken.” – ECan warning letter

Documents released to Newsroom under the Local Government Official Information and Meetings Act reveal the Lake Emma incident was raised while Toogood was notifying ECan of another spraying incident, this one in the Peel Forest Scenic Reserve. (Toogood’s initial opinion – which was spot on, as it turns out – was Lake Emma’s non-compliance was “nowhere near as clear cut” as Peel Forest.)

A DoC staffer had sprayed an amenity area for blackberry in November 2019. But in September last year, a member of the public complained about die-off of native plants in a Peel Forest wetland, prompting DoC’s mea culpa to ECan.

Toogood tells Newsroom, via email: “DoC takes its environmental responsibilities very seriously and wanted to clarify whether a regulations breach had occurred, what the severity was, and what could be done to remediate the site.”

An internal email written by ECan’s Michael Nolan, an incident response officer, says a 1.3ha area had been sprayed, but less than half the affected area was wetland. Soil samples came back clear for contamination. The main concern was the death of “about 15 native trees and associated shrubs, ferns and groundcovers”.

Spraying of the Peel Forest amenity area was approved by DoC’s recreation team, Nolan writes last October, but that approval did not include the wetland area. The staff member – who DoC confirms is still working for the department – denied responsibility for the die-off to ECan. “She did not believe the area was a wetland as defined in the RMA.”

Last December, ECan formally warned the department for clearing vegetation in a wetland.

Enforcement action was considered but was dropped after a remediation plan was agreed, says the letter, released to Newsroom yesterday.

“Failure to implement this plan within the stated timeframes and as agreed may require us to revisit this outcome,” Nolan wrote. “The environmental impact of such an activity could be significant and if a similar offence were to reoccur in the future it is likely that enforcement action would be taken.”

Meanwhile, no action was taken over spraying at Lake Emma. ECan determined none of its rules or consent conditions were breached.

After consulting with its freshwater ecologist, ECan found there would have been little effect, if any, on intermittent waterways running through the sprayed area, and “no effect” on the nearby lake. The vegetation clearance might have breached Ashburton District Plan rules, but the district council told ECan “they don’t normally get involved with conservation estate vegetation clearance issues”.

Forest and Bird Canterbury and West Coast regional manager Nicky Snoyink is gobsmacked to hear about two cases of over-spraying involving DoC. “It’s not what you expect from the department.”

She says it’s fair to wait for the conclusions of the department’s investigation before leaping to judgment about what happened.

“A review of our processes is being done as part of the investigation and further changes may be made once this is complete.” – Duncan Toogood

The narrative about the spraying has morphed, somewhat, over time.

In early December, a short, emailed statement from Valyn Barrett, ECan’s regional leader of RMA investigations, described it simply as a “minor incident”. Asked for further details, Barrett said there was evidence of “overspray and poor operator execution”. While “some” native plants were affected, the overall environmental effect was minor. (We now know “some” meant “hundreds”.)

Newsroom asked for further information under the Local Government Official Information and Meetings Act, which revealed the Mt Peel incident.

ECan sent a copy of its statement to DoC, after which the department responded to Newsroom’s questions. A statement on December 7 from South Island operations director Nic Toki said the issue was caused by “aerial spraying” by a DoC contractor in January. However, LGOIMA information from ECan stated there was also ground control by a DoC staffer. The spray season extended from January 14 to March 19.

“Now ECan’s findings have been passed on, DoC is looking into the incident,” Toki said in December. “We are reviewing processes to ensure something like this does not happen again and have put weed control work in the area on hold until this is done.”

However, that’s not what happened.

On Monday, a written statement from DoC Geraldine’s operations manager Toogood says work only stopped temporarily.

“Weed control work has restarted to take advantage of the summer season, but there is an interim requirement in place for staff to provide a detailed description of all planned spraying work to the district manager and gain written approval before doing the work.”

He adds: “A review of our processes is being done as part of the investigation and further changes may be made once this is complete.”

Remediation work hasn’t been done at either site, either. Toogood says a planting plan at Peel Forest has been endorsed by Te Rūnanga o Arowhenua and accepted by ECan. Planting will happen in spring.

Remediation for Lake Emma is still being planned, Toogood says – more than a year after the spraying happened, and two-and-a-half months after the formal warning. “The shape of the final plan will depend on how well the area regenerates naturally.”

Asked if the DoC staffer was adequately trained, Toogood says the department is still investigating how the incidents occurred and it can’t comment further while the investigation is ongoing.

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

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