Environmental co-ordinator Erin Cullen told Judge James Walsh she was well aware of a trio of failed “acute lethality” tests on rainbow trout, using wastewater from the mine site in October 2011.

However, “I still don’t relate the failure of the laboratory test to a real-world impact,” she said.

As reported, she vouched for the samples gathered at site and the work of the laboratory involved on the island side. But she did not agree the nearly half a billion litres of wastewater represented by the samples was ultimately damaging to the environment, based on her understanding of what had caused the test failures.

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Vale Newfoundland and Labra­dor is accused of violations of the federal Fisheries Act, with the accusations tying back to the failed tests.

In court, it was noted the company had repeated, similar failures in the same compliance test in 2008, 2009 and 2010 — 27 failures in the latter two years alone, by available provincial government records.

Cullen was able to speak in court to a summary of environmental-effects monitoring from that period, covering the area where the wastewater ended up in Anaktalak Bay. Followup testing, the court heard, showed no statistically significant environmental effects.

“Your honour, other than (the wastewater) being acutely lethal effluent, there were no additional steps taken,” said Environment Canada investigator Gary Kennell, when he was asked at another point for any reports the regulator might point to in order to demonstrate real-world environmental damage.

He said someone else was responsible for the company’s environment-effects monitoring reports. He didn’t review them.

He also could not say with certainty what caused the failed “acute lethality” tests. The circumstances around the company’s continued release of wastewater after the failed tests is something he investigated, but not the root cause of the failures.

Cullen, on the other hand, laid out her thinking, as well as the company’s detailed followup and findings.

The earlier, failed compliance tests in 2008-10 led Vale Newfoundland and Labrador to establish a task force of internal and external specialists to address the problem.

The company thought they had done so, with the installation of additions to the effluent treatment plant, and disbanded its “toxicity investigation task force,” before the test failures of October 2011.

Cullen was appointed to lead the task force as it was re-established, in the midst of the failed tests now at issue.

Even from the time of the failures, there was no sign of metals or other contaminants being the problem, it was said.

The company launched into detailed study, continuing to this day. Cullen said the ultimate finding, however, is the problem tied back to the alkalinity of the wastewater before it reached the treatment plant.

The alkalinity is the ability of the water to neutralize acids, and the explanation as to what went wrong involves a complex interplay between the potentially acid-generating tailings from the mine, seasonal changes in the environment and the alkalinity of the wastewater.

“Vale is continuing with a toxicity evaluation program in efforts to prevent any further discharge of effluent that is toxic to rainbow trout,” stated a provincial government report from 2013, noting one failed acute lethality test in that year.

The trial continues.