Shotover Wastewater Treatment Plant in Queenstown. Photo: Supplied / Queenstown Lakes District Council
Queenstown Lakes District Council has been told it must stop discharging treated wastewater to land after high levels of nitrogen were detected in the Hāwea oxidation pond.
An abatement notice was issued by the Otago Regional Council on 18 March, after nitrogen levels in wastewater at the Hāwea Wastewater Treatment Plant were found to breach the consented levels allowed over a 12-month period.
The notice said the total mass of nitrogen discharged to the land treatment area and soakage trench must not exceed 4726 kilograms in any continuous 12-month period, but data provided by Queenstown Lakes District Council showed that 5345kg of nitrogen had been discharged in the 12 months before December.
It also included details of eight additional breaches between June 2024 and January 2025 and said the district council had failed to provide the regional council, which was the consent authority, with incident reports within 20 working days in every case.
It comes after the Queenstown Lakes District Council was criticised over plans to discharge treated sewage into the Shotover River.
The council is using emergency powers to pump 12,000 cubic metres of effluent into the Shotover each day and maintains it is well within its consent limits.
Queenstown Lakes District Council general manager of property infrastructure Tony Avery said it had tried to resolve fluctuating nitrogen levels by upgrading the plant's treatment processes and while there had been some improvements, the levels remained above consented limits.
He said the breach and abatement notice were disappointing but environmental monitoring of the Hāwea River had shown there were no adverse effects associated with the treatment plant's elevated nitrogen levels.
"Treated wastewater is discharged to land either via the facility's land treatment area or an infiltration trench, both of which are located downstream from Lake Hāwea and ultimately drain through to Hāwea River," he said.
"As a priority, staff are exploring further measures to improve performance and to bring the plant back into full compliance with its consent conditions."
He said given the historical non-compliance of Hāwea's treatment plant and the need to cater for significant growth in the catchment, plans were in place to connect the township to Project Pure/Wānaka Wastewater Treatment Plant.
The planned connection was part of the wider Upper Clutha Wastewater Conveyance Scheme project, which would see significant investment in wastewater management across the Hāwea and Wānaka schemes.
Funding for the project was included in the adopted in the district council's 2024-2034 long term plan, with an overall budget of $80.1m.
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