Modified testing of the Shotover Wastewater Treatment plant will see site visits moving from weekly to monthly, despite a recent trend upwards in E.coli results.

The last E.coli reading from the plant discharge into the Shotover river on July 27 was well above the average 250cfu (colony-forming units) per 100ml.

Test results have been slowly tracking upwards from the site in recent weeks - the highest being 340cfu/100ml from the waste water treatment plant.

Otago Regional Council (ORC) environmental delivery general manager Joanna Gilroy said when an elevated result is recorded, Queenstown Lakes District Council (QLDC) is required under the enforcement order to undertake sampling five days a week for three weeks to confirm the finding.

But the most recent water quality reporting on the QLDC website is from six weeks ago.

“This follow-up sampling is currently underway,” Joanna said.   

“Within the last two months ORC has also detected one elevated result for total suspended solids.”

She said ORC is closely monitoring the sampling undertaken by QLDC and the monthly sampling and site audits will continue to validate the results collected by them, along with the weekly sampling of the Kawarau River at Chard Road.

“ORC will continue to respond to any incidents on site and this remains a high priority site."

Past readings showed the discharge from the plant into the Shotover River between just 24-30cfu/100/ml during June. But downstream of where it meets the Kawarau River, the levels had dropped back to just 4cfu/100ml.

ORC started weekly testing at the end of March of wastewater downstream of where QLDC has an emergency discharge consent.

Some initial monitoring on the first day of the discharge showed high levels of contaminants present - up to 750cfu/100ml, which the regional council said was expected with the flushing of the wastewater outlet channel, which bypasses the disposal field.

In recent months the discharge levels had settled. ORC said its decision to reduce the monitoring balanced the need to ensure a robust monitoring programme (which provides assurance to both Queenstown residents and those downstream from the discharge) with the need to ensure prudent financial management, where appropriate monitoring and oversight is already in place. 

Central Otago leaders interviewed about the issue in the past have always been confident that “dilution is the solution”, but there are still concerns about the latest testing results.

Central Otago District deputy mayor Neil Gillespie, who is currently running for a seat on ORC, said the fact there are still high level readings at the source shows the plant is not compliant, and the problem has not gone away.

“And that’s why there is an enforcement order in place.”

ORC said the monitoring could change again, and be reconsidered once a decision was reached about the QLDC consent, or if there were any impacts on the environment, or when upgrades were made at the site.

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