The public can have its say on the controversial subject by making written submissions until November 3, which will be followed by a public hearing.
Two resource consent applications from the Queenstown Lakes District Council were notified by the Otago Regional Council on Saturday.
One covered disposal of treated wastewater to the Shotover River and construction of an outfall structure.
Retrospective consent has been sought for the discharge, which started on March 31 under emergency powers.
The other application was to construct and operate a diversion channel within the riverbed.
It was determined both applications should be publicly notified, because they were considered to be linked and there was significant public interest in the proposal as a whole.
Queenstown Lakes District Council property and infrastructure general manager Tony Avery described the Kimiākau Shotover River as a significant natural resource that also had cultural value.
The proposed channel would ensure the discharge "is always to flowing water", he said.
"With that discharge already under way and one of the applications requesting retrospective consent to do so, council continues to closely monitor multiple locations in both [the] Shotover and Kawarau rivers to ensure we have a full understanding of any effects on the environment."
Otago Regional Council consents manager Alexandra King said the submissions period would be six weeks, rather than four, because of the high level of public interest.
The Environment Court will decide on the applications.
A regional council notification recommendation report described background to the Shotover wastewater treatment plant and associated discharges as extensive and complex.
Incidents there were the highest-priority investigation for the regional council and compliance monitoring was ongoing, the report said.
In June this year, the Environment Court approved the regional council’s application for an enforcement order, laying out a series of required actions, including increased sampling and improvements to the treatment plant.
The district council had a series of problems with its land-based disposal system known as "dose and drain" since 2021.
The council invoked emergency powers this year amid worries about ponding at the disposal field leading to increased waterfowl activity in the area, elevating the risk of bird strike for aircraft near the town’s airport.
Treated wastewater was then diverted from the disposal field and discharged directly into the Shotover River.
In May, the district council requested one of its consent applications — regarding the Shotover discharge and outfall structure — be publicly notified.
In a report for the regional council dated September 16, consultant planner Hannah Goslin recommended the application about the diversion channel should also be publicly notified.
Independent hearings commissioner for the regional council, Robert van Voorthuysen, agreed.
