Fine silt from Port Otago's off-shore dumping could have a
"disastrous" effect on the coastal kelp forests on which rock
lobster, paua and kina rely on for survival, Otago fishing
The effect of Port Otago's proposal to dump silt 6.5km off
Taiaroa Head as part of its Next Generation plan to dredge
7.2 million cubic metres from the existing shipping channel
and swinging basin in Otago Harbour to allow large ships
entry, is being heard in the Environment Court in Dunedin.
The Otago Regional Council granted consent subject to
conditions for Port Otago to carry out the project in 2011
and shortly after it was appealed.
While the East Otago Taiapure management committee, New
Zealand Federation of Commercial Fishermen, Southern Clams
and Otago Rock Lobster Association have settled most of their
concerns with the port company, they continued to appeal
conditions relating to the unproven effects of the sediment
dumping on the disposal site and the rocky seashore to the
west of the site.
Environment Court Judge Jeff Smith, of Auckland, who is
hearing the appeal alongside commissioners Alex Sutherland
and Anne Leijenn, said the goal of the hearing was to ensure
the coast of Otago was kept free of the adverse effects of
the sediment dumping.
The court was not concerned with whether Port Otago's model
was right or wrong but how any potential effect could be
avoided, remedied or mitigated in the event of it all going
"belly up", he said.
"Once it's in suspension and onshore there is not a lot that
can be done about it."
Phil Page, counsel for the fishing interests, said they were
concerned about the unmanaged risk that fine sediment would
find its way into the near-shore environment and the
potential effects would be "disastrous" for the kelp forests
and the shellfish that relied on the rocky habitat for
"Modelling is not the same as monitoring. Modelling ... tells
us nothing about what actually is happening to the
They feared that by the time problems started becoming
apparent, it would be too late to do anything about it, Mr
There was nothing in the conditions requiring Port Otago to
conduct near-shore monitoring of fine-silt dumping.
Len Andersen, counsel for Port Otago, said the movement of
the sediment plume from the dumping had been modelled under
"worse case" scenarios and it was predicted any sediment
ending up on near-shore would be in quantities too small to
be discernable, "let alone cause adverse effects".
Monitoring at the dump site was proposed to verify that
The company could not categorically prove there would be no
adverse effects on the near-shore as the model had not been
verified with field data.
It could also not identify what would constitute a trigger
level for dumping to stop, due to turbidity levels.
Alastair Logan, counsel for the Otago Regional Council, said
the consent had been granted on the basis the modelling was
correct and there would be no adverse effects on the inshore
A staged approach to the disposal of dredged material at the
off-shore site was appropriate with a verification stage,
including monitoring of sediment dispersal, followed by an
operational stage for both the small and large dredge.
At the end of the monitoring stage, the council would look at
the data and consider whether to review the consent, he said.
The hearing was adjourned for the panel to visit the dump
site via helicopter. It will resume today.