Wanganui District Council expects to find out on Thursday whether foul smelling sludge at its wastewater plant has reduced enough, to begin treating the problem.
On Wednesday, Manawatu-Whanganui Regional Council issued Wanganui District Council with an abatement notice, asking it to have the odour cleared up in four weeks or face a fine.
Mayor Annette Main said companies have been dumping more than they should have been since 2007, causing sludge to build up to levels not expected for 20 years.
She said the council is checking the depth of the sludge to see if it is reduced enough for aerators to be turned on again.
