Christchurch residents have again reported strong odours linked to the Bromley wastewater treatment plant, prompting an apology from Christchurch City Council and renewed calls for accountability from Environment Canterbury.

The council said odour was “particularly noticeable for a period” on Thursday morning, with the issue detected by monitoring equipment.

“We know that the odour was particularly noticeable for a period this morning, and this was picked up on some of our odour monitors. We’re sorry for the disruption this may have caused,” the Christchurch City council said.

“While we had taken steps to manage the impact of the recent rainfall event, these situations are unpredictable and we knew some odour was possible,” the council said, adding that improved weather conditions had helped the smell subside.

The council said odour levels can change quickly due to weather and environmental factors and confirmed the situation would continue to be closely monitored, with a further update expected on Monday including hydrogen sulphide data.

Environment Canterbury chair Deon Swiggs said he had seen an uptick in complaints throughout the day and described the ongoing problem as disappointing for residents.

“The stink spreading across the city again is really disappointing for our community,” Swiggs said.

Swiggs said the wastewater treatment plant, owned and operated by Christchurch City Council, must meet consent conditions preventing odours from extending beyond the site boundary.

“I can say that there is an ongoing investigation into these odour issues, and I’m committed to ensuring accountability and solutions with our staff directing action to be taken,” he said.

“Our communities, particularly in the eastern suburbs, deserve better,” Swiggs said.

Residents experiencing odours have been encouraged to log complaints through Environment Canterbury’s reporting system, with Swiggs saying community reports help build evidence for potential enforcement action.