DCC defends water quality

Photo: File
Photo: file
Dunedin residents should have confidence their drinking water is safe despite a 40% non-compliance rate with stricter new standards, the city council says.

They should also have confidence progress is being made towards achieving those standards, councillors have been told.

Compliance with water and wastewater regulatory requirements were discussed at a Dunedin City Council infrastructure services committee meeting this week.

Council Three Waters and transition general manager David Ward said there had been a paradigm shift in recent years for regulating water — it had moved from a system similar to a vehicle getting a warrant of fitness to much more regular assurance through sampling, monitoring and reporting, including reporting at 15-minute intervals.

"That’s where we are dramatically improving our position," Mr Ward said.

"We are exceedingly confident the water we produce is of sufficient quality."

The council submitted its first annual compliance report for the drinking water regulator, Taumata Arowai, in February and it included about 40% non-compliance for last year.

The Otago Daily Times followed up with further questions.

"We have a range of monitoring and other processes in place, and we remain confident our water is safe for public consumption," a council spokesman said.

"We are working to address issues of non-compliance, many of which are administrative or technical in nature and have arisen due to recent regulatory changes.

"Some have already been resolved and others will be."

A report for the committee highlighted that in April the council became aware ultraviolet reactors at the Outram and West Taieri water treatment plants may not have been compliant for protozoa removal.

Permanent control modifications had since been made and the plants were now compliant, councillors were told.

The water safety risk was relatively low and a precautionary approach was adopted, the report for the committee said.

Asked for more information, the council said the provider of the UV light disinfection system used at the plants made it aware of a potential technical issue with the equipment in April.

"Because we take our duty of care extremely seriously, we introduced additional water monitoring — over and above our regular water quality sampling — and manual changes to water treatment processes as a precaution," a council spokesman said.

"Subsequent testing has confirmed the equipment is operating as intended and water from both plants remains safe for public use, so a public advisory has not been required."

Taumata Arowai said the council took appropriate action to maintain public health.

The council is dealing with abatement notices relating to its operation of the Tahuna, Warrington and Waikouaiti wastewater treatment plants.

The Otago Regional Council imposed the notices on the city council for the Waikouaiti and Warrington plants in June 2022 and for the Tahuna plant in February this year.

Upgrades at the Warrington plant had brought its discharge to land into compliance for total nitrogen, the city council said.

The abatement notice has a deadline of November 30 this year but the council signalled it could seek to have the notice cancelled early.

Monitoring at the Waikouaiti wastewater treatment plant indicated the discharge to land was improving and the limit for ammoniacal nitrogen could be complied with by November.

The city council was assessing the relationship between improvements in discharge quality and plant operational changes.

The Tahuna plant in Dunedin was not complying with its air discharge limits for oxides of nitrogen.

Options were being assessed and the compliance deadline was December 2.

A council spokesman said compliance was a high priority.

The council was confident of achieving compliance at Warrington by November and at Waikouaiti by the end of the year, he said.

"Tahuna may take longer, but we are in close contact with the Otago Regional Council about this, too."

Regional council compliance monitoring team leader Mike Cummings said ensuring compliance with resource consents and rules was a key role for the organisation.

"Council has taken appropriate action to address the non-compliance by issuing abatement notices," he said.

The city council was responding to the notices, he said.

grant.miller@odt.co.nz

 

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