An investigation of sheep dip sites across Tasman has found old community plunge dip sites tend to be heavily contaminated with levels of arsenic and dieldrin exceeding human and animal health standards by up to 25 times.
District resource scientist Paul Sheldon said with the help of $14,000 from the Contaminated Sites Remediation Fund the council located and assessed 11 dip sites.
Mr Sheldon said the degree and extent of contamination around old dip sites meant the best solution was to fence them off and retire them. Contamination levels reach 1000mg/kg for arsenic and 25mg/kg for dieldrin. Both community and private plunge dip sites also showed elevated zinc levels which substantially exceeded Dutch and Canadian standards. New Zealand does not have zinc limits.
Newer dip sites generally showed lower levels of contamination. Mr Sheldon said there were probably plenty of old dips sites around Tasman the council was unaware of and he welcomed information on possible sites.
"The risk is the land gets redeveloped and someone ends up growing food on contaminated land without knowing it."
Meanwhile results of Mr Sheldon's surveys of the district's formal and informal mooring and hard stand boating areas has shown some heavy concentrations of zinc and copper.
Mr Sheldon said contamination tended to be lower around informal swing moorings and public boat launching areas, like Grossi Point in Mapua.
But Westhaven's hard stand, the ramp and rail at Waitapu Wharf and the hardstand at Port Motueka showed levels of copper and zinc hundreds of times over guidelines.
Mr Sheldon said new antifouling guidelines, would soon make specific recommendations of maintenance.
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