The current odour issue being experienced in Te Anau is likely to be the result of a combination of factors, says Southland District Council strategic manager water and waste Ian Evans.
High loadings to the wastewater treatment ponds as a result of tourist numbers, combined with a long spell of warm weather and low rainfall, mean the ponds have encountered this issue.
“In technical terms, the first part of the pond has flipped over,” he says, causing organic material to rise to the surface and releasing gas, which contributes to the odour.
Council staff are working to resolve the issue and have undertaken steps to restore the system. These include addition of extra aeration, dosing of lime and other chemical to restore the balance of the system and removal of the sludge from the surface of the pond. It is a biological system and may take time to fully correct, Mr Evans says, although people should see an improvement with rain forecast for the weekend.
Council staff and contractors are continuing to monitor the situation and will consider further actions if required.