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Dunedin City Council – Kaunihera-a-rohe o Otepoti
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Environmental monitoring

The DCC monitors the environmental effects of discharging treated wastewater into the sea.

Where we monitor

The sites we monitor include Blackhead, Beachlands, Westwood, Second Beach, Lawyers Head, Smaills Beach, Boulder Beach, Sandfly Bay (south and north end), Hoopers Inlet Mouth, Boulder Beach, Allans Beach and Victory Beach.

What we monitor

We monitor:

  • the quality of treated wastewater discharge
  • the quality of sea water for swimming and shellfish gathering
  • the effects on rocky shore and deep water ecology
  • shellfish and sediment quality.

The monitoring is done by an independent environmental consultant, and an independent laboratory does the testing.

What we have found

Monitoring reports are prepared annually – see the related information area. Overall, monitoring shows the discharge does not significantly affect the environment:

  • Testing shows that treated wastewater is diluted to an acceptable level in the mixing zone around the outfall. Divers examining the outfalls report healthy and varied marine life around them.
  • The sandy and rocky shore communities we examine are healthy and show no changes beyond what happens naturally.
  • Some shellfish at most sites, including the control site, are affected by contaminants. However, this contamination could come from several sources, including stormwater discharges, land runoff, seabirds, fur seals and other marine mammals in the area.
  • There is no evidence of the discharge affecting coastal sediments.

In 2016, Golder Associates (NZ) Ltd prepared a report on the performance of the Tahuna wastewater treatment plant since it was upgraded. You can find the report in the related information area.

For information about Dunedin’s beaches, see our Beach  Water Quality page in the related information section.

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