Wānaka toilets were flushed so much over the new year holiday period the Project Pure wastewater treatment plant near Wānaka Airport overflowed.
Both the Queenstown Lakes District Council (QLDC) and its regulator the Otago Regional Council (ORC) took action after a complaint was lodged to the ORC pollution phone line on January 4.
Wānaka’s treatment plant was close to the Clutha River but wastewater had not reached water bodies, council staff said.
QLDC communications spokesman Sam White confirmed on Monday surface ponding of treated effluent occurred at the disposal field over New Year.
"This is now under control and the situation is improving daily back towards full compliance.
"The wastewater treatment plant struggled with high flows caused by peak holiday demand resulting in lower-quality effluent being released to the disposal field via the normal treatment process.
"This in turn caused some treated effluent to break through to the surface of the field.
"However, this was localised, did not enter any body of water and occurred in an area inaccessible to the public.
"Council staff and contractors acted quickly to address the cause and restore performance.
"Flows to the [treatment plant] naturally reduced in line with visitors leaving after New Year and additional capacity at an adjacent disposal field, already scheduled to come online shortly, will also help," Mr White said.
Otago Regional Council compliance manager Tami Sargeant said staff were still investigating the breach in compliance.
The immediate priority was to ensure the QLDC complied with resource consents and rectified environmental effects.
"Immediate actions were taken by QLDC and Veolia (a resource management company) to address the issues, and QLDC has been providing regular updates to ORC on actions taken.
"These actions have ensured no treated wastewater has gone on to neighbouring properties, which is our primary concern," Ms Sargeant said.
ORC staff would continue to visit and monitor the plant.
No formal enforcement decisions had been made, she said.
Asked if the regional council had concerns about pressure on Wānaka’s infrastructure over the busy New Year’s Eve period, Ms Sargeant said that was "not for ORC to comment on".
Whether Project Pure should be expanded to cope was also a matter for the QLDC, she said.
Mr White said the two councils were working together closely.
He said the QLDC would keep the regional council fully informed as the site returned to compliance and it would share its incidence report with the ORC.
By the numbers
Project Pure wastewater treatment plant
$17.2 million: Set aside for Project Pure upgrades in June 2022-July 2023.
2041: Project Pure consent expires.
20km: New Project Pure link from Hawea.
5: Treatment plants in district (including Project Pure).
14,521cu m: Average wastewater discharged in the district daily.
SOURCES: QLDC website; 10-year plan 2021-31; annual plan 2022-23.
