Wanganui District Council has been issued with an abatement notice by Horizons Regional Council following ongoing smells from the city's wastewater treatment plant.
Horizons group manager strategy and regulation Nic Peet said the notice was a legal directive requiring the council to cease causing an objectionable odour beyond the boundary
of its plant within the next four weeks.
It follows a formal warning issued in December 2012.
Dr Peet said that, while Horizons recognised solving issues might be difficult, the odour was objectionable and its ongoing impact on the people of Wanganui meant it must be resolved.
"Industrial processes like those occurring at the wastewater treatment plant will always produce an odour. It becomes an issue when an objectionable odour extends beyond the property boundary, affecting other residents and businesses, as is clearly the case in Wanganui.