The ANZCO Kokiri site borders the Arnold River inland from Greymouth where the company holds a resource consent allowing it to discharge treated effluent into the river via an outfall pipe.
But in September ANZCO approached the West Coast Regional Council with an admission its river quality monitoring data lacked credibility, acting consents and compliance manager Chris Barnes said.
Barnes said it was attributed by ANZCO, "to an individual basing required river sampling on previous results" and they admitted their yearly environmental reports "had not been credible" for the past three years.
"It was also revealed that access to the sampling sites had been documented as a safety issue in the past," he said.
Council subsequently launched an investigation which has yet to be concluded.
Barnes said they await further information from ANZCO on the circumstances including why the matter had been able to escalate.
"They've come to us, they've self-reported a breach, but they say it's from an individual that's caused this, but they won't give us any further information on that," Barnes said.
LDR approached ANZCO with questions about its cooperation with the council's inquiry. This included why ANZCO discovered the breach, and if the company was confident its river monitoring data prior to the three year period reported was also credible.
It did not directly respond to those questions but the company said it "took the matter seriously".
ANZCO Foods general manager operations Darryl Tones said they identified "a potential issue" last August with one of its reporting consent conditions for the Kokiri site.
As a result they immediately imposed "measures and processes" to ensure the correct data was being collected and reported.
Tones said as soon as the company became aware incorrect river sampling data had been provided for the previous three years, it met with council immediately "to apologise and explain".
"We took this matter very seriously and once the issue was identified we immediately took steps to ensure we were complying with our reporting conditions," Tones said.
ANZCO had also outlined to council "remedial actions" taken by the company.
Tones said water quality testing was an important part of ANZCO's responsibilities as "a good corporate citizen".
However, Barnes said the failure at ANZCO's end was "pretty blatant and serious" and a matter for their reputation.
ANZCO was required to provide the council with annual reports of its water quality testing based on samples from the river six times a year and from 300m below the effluent outfall.
"What they have to do is test 300m down from the discharge - that's the requirement. Their testing there has been an issue when the river levels are up… we're still awaiting further information."
In the meantime, the council wanted "a better explanation" before it took further steps.
This included "how well they have tested in the past," he said. "We are still investigating - we're in the stages of making a preliminary finding."
The Arnold River is internationally and domestically reputable as a highly desirable angling river. Its source is Lake Brunner and it runs into the Grey River.
Tones said the company recognised the Arnold River as important to the local community and the company had created a public access so people could enjoy it.
Brendon McMahon, Local Democracy Reporter. LDR is local body journalism co-funded by RNZ and NZ On Air.
