Up to 200 litres of diesel oil may have been spilt in the Napier inner harbour during the past few days after a private fishing vessel was discovered fully submerged in the spot it had been moored.
Only the antennae of the boat were visible when Hawkes Bay Regional Council staff were alerted to it about midday yesterday, and they immediately deployed booms to contain the oil and lifted the boat from the water.
It was unclear if rough weather conditions contributed to the boat sinking or how much oil had been spilt but a boat of its size was capable of holding a couple hundred litres of diesel and another 10 litres of engine oil.
"We haven't done an estimate at this stage," regional council environmental officer Ian Lilburn said.
"We'll need to talk to the owner [about] how much oil was in the vessel in the way of diesel and then there is also obviously engine oil from the bilge area as well.
"The vessels that have been moored along Nelson Quay here have got traces of oil along their hulls stuck to their boat, so there is going to be a little bit of a clean-up there."
The regional council was asking the owners of boats moored nearby to phone the Hawkes Bay Regional Council's pollution hotline for advice on cleaning their boats before they washed them down, to avoid more pollutants going into the water.
Mr Lilburn did not know when the boat had sunk, but suspected it had been submerged for several days.
"We've noticed oil sheens in the harbour here for the last two days but we've never been able to track down where they're coming from," he said.
"Now we've found the vessel, which was virtually out of sight, we suspect what we've been seeing over the past two days has actually been diesel sheens that have come out of this vessel. We suspect it's been submerged for several days."
The owner of the boat had been down to have a look at it but how much diesel was inside it at the time had not yet been discussed with council staff.
Work to contain the oil was to continue today.By Corey Charlton