Monday 21 May

Complaints of dead fish and significant odour at Wainui Stream earlier this week has been investigated by Council staff.

The incident appears to have been caused by the rotting of organic matter built up in the stream from garden waste and lawn clippings dumped along the stream’s catchment.

With the arrival of heavy rain on Sunday, the decaying matter that had settled at the bottom of the stream has washed down causing a drop in oxygen levels in the water, leading to fish deaths and the release of hydrogen sulphide causing an unpleasant odour.

Previous investigations into the health of the stream have identified vegetation and green waste as a contributor to the poor water quality.

While Council has ongoing concerns about the presence of faecal indicator organisms in the Wainui Stream the investigation this week did not identify any specific sources.

Director Environmental Services and Protection Nick Zaman says the construction of the Tamarau Wetland at Heath Johnston Park will help improve water quality in the Wainui Stream.

“We urge the community to help improve the water quality and avoid dumping green waste and lawn clippings into this environment.”

Further monitoring of the build-up of organic matter and how this impacts water quality during first-flush events will be undertaken.

ENDS

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