Zinc targeted by ARC as levels on rise in harbours

29 July 2005

Reducing zinc levels in Auckland harbours has been identified as a stormwater management priority by the Auckland Regional Council.

The ARC Stormwater Action team, set up in February to implement the Regional Stormwater Action Plan, has defined zinc, copper, sediment and water quantity as the biggest threat to aquatic life in Auckland’s streams, estuaries and harbours.

The Stormwater Action Plan was developed by the ARC to address increased pollution of Auckland’s waterways as the region grows.

SWA team leader Earl Shaver says zinc is a high priority contaminant on which to take action, because zinc levels in the harbour are increasing so rapidly.

“Many animals that live on the ocean floor cannot survive if zinc levels in sediment are too high,” Mr Shaver says. “Once animals such as cockles and pipis living on the sea bed die, a domino reaction occurs right up the food chain as fish like snapper and flounder run out of food to eat.”

Studies showed that the main source of zinc in Auckland’s waterways is the stormwater run-off from unpainted, galvanised roofs, particularly industrial roofs due to their size.

“The short-term solution to zinc run-off from roofs is to paint the roofs,” Shaver says. “We are going to be working with industry to get roofs painted, but ultimately we want to see zinc taken out of roofing materials altogether – if we can achieve this, then we expect to have zinc-free roofs in the Auckland region within the next 50 years.”

ARC Environmental Management Committee Chair Cr Dianne Glenn says all the signs point towards Auckland’s harbours reaching crisis point if action is not taken to reduce contaminants from getting into waterways.

“Imagine a future with no snapper, flounder and shellfish in the Waitemata and Manukau harbours,” Cr Glenn says. “This could be a reality if we don’t take responsibility for our actions now, by making the changes needed to protect the health of our iconic harbours for future generations.”

ENDS

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