Crews are urgently responding after an overflow of partially treated wastewater entered a pond in Queenstown today.

The effluent had made its way from one of the oxidation ponds at Shotover wastewater treatment plant after it overtopped.

Queenstown Lakes District Council (QLDC) acting general manager of property and infrastructure, Simon Mason said wastewater had made its way from the pond to a small section of natural swamp nearby, but understood no contamination had reached Shotover River.

“Crews are currently on site working to resolve the issue and determine exactly what has caused the pond to overtop,” said Mason.

Shotover Delta Rd has been closed as a precautionary measure as council contractors and officers make the necessary repairs.

Walking tracks in the area remain unaffected and open to the public.

QLDC has notified Otago Regional Council’s (ORC) pollution team of the overflow, and ORC compliance officers are on-site to investigate.

The spill is not linked to ongoing repairs at the Shotover wastewater treatment plant, as crews continue to work to resolve problems with the facility’s aeration grids.

The Queenstown Lakes District Council (QLDC) understood no contamination had reached Shotover River. Photo / Supplied

Mason said a temporary aerator was in operation at the treatment plant, and spare parts from the United States had arrived and were currently being installed at the facility.

“As these repairs are made, the biological process treating the wastewater will progressively recover over the coming days and weeks and we hope to see the end of odour in the area soon after that,” he said.

It comes after wastewater gushed from a leak at the Albert Town pump station along State Highway 6 on January 10.

QLDC confirmed wastewater did not enter the Clutha River.

“Council contractors worked through the night to identify the full nature of the fault, repair it and mitigate the flow of wastewater,” QLDC said in a statement.

“This was achieved by bypassing part of the flow to the old Albert Town oxidation pond behind Jack Young Place, and removing the remainder via a fleet of sucker trucks.”

More than 50 people contracted the gastro bug cryptosporidium during an outbreak in Queenstown in September, most likely linked to human faecal contamination of the water supply.

Te Whatu Ora said based on all the gathered information, its most likely hypothesis was that the outbreak started through human faecal contamination of the source water in Lake Wakatipu, which has then been collected into the Two-Mile water treatment plant’s intake pipes, then moved into the water reservoir.

“From there, it has then been distributed around the Two-Mile water distribution network to homes and businesses, most likely over a number of days.”

Previously, officials were unsure the source would ever be known.

Benjamin Plummer is an Auckland-based reporter who covers breaking news. He has worked for the Herald since 2022.