Horizons Regional Council may initiate court action over the smells still lingering about Wanganui and its waste treatment plant.
Wanganui Council were issued an abatement notice requiring it to stop causing "objectional odour" beyond the boundary of the plant by 5pm yesterday.
Despite dropping lime and boosting oxygen levels in the ponds to alleviate the smell it has not gone away.
"Monitoring yesterday afternoon and this morning has indicated that there are still odour problems beyond the boundary of the plant," said Horizons Regional Council's Nic Peet.
But Wanganui Mayor Annette Main says it will not be completely fixed until there is a long term solution for the plant to work properly.
The waste water plant has been plagued by problems since its opening in 2007.
Experts say it is never been able to cope with the volume of waste. Some local businesses have been blamed for dumping too much.
But it is the council's responsibility to fix it. And the region's environmental authority are looking at taking things to the next level.
"Potentially the next course of action is that we seek a thing called an enforcement order from the Environment Court," Peet said.
An enforcement order will likely result in a jointly-agreed action plan monitored by the court.
Wanganui Mayor Annette Main says it is a good thing.
"But it won't completely be fixed until we have actually got a longer term solution for the plant so we have to get this plant working properly in order to keep this odour down."
Whether court action is taken will depend on the next few days, with monitoring of the stench set to continue over the weekend.