Bad weather is preventing checks to see if diesel is leaking from a sunken launch near Whitianga, says Waikato Regional Council.
The boat was carrying about 200 litres of marine diesel when it sank, after clipping a rock and starting to take on water in Humbug Bay on the Coromandel Peninsula on Friday night.
The four people on board managed to swim to a rock at Devil's Point and were taken to safety by Coastguard's rescue vessel.
The council's regional on-scene commander Derek Hartley said the windy weather could help disperse any diesel that leaked from the wrecked boat.
"If it does escape into the environment, the agitation of the sea breaks up the volatile hydrocarbons and quickly breaks it down to its constituent elements again," Hartley said.
"Marine diesel oil in itself is significantly eco-toxic, but the amount and considering the weather conditions, we don't anticipate it's going to be a significant environmental threat."
Whitianga Coastguard operations manager Graham Caddy said strong winds yesterday made it impossible to salvage the launch, so it was left to break up.
"Coastguard have put out warnings over our VHF channels, warning boaties of the potential danger of debris for the next few days to a week," Caddy said.
"This is just the natural course of boats that are caught on rocks unfortunately, they can't be salvaged in time."
Parts of the launch were likely to wash up along Matapaua Bay, Caddy said.
Waikato Regional Council would continue to monitor the situation, Hartley said.
RNZ
