UPDATED: Mobil Oil New Zealand has been fined $288,000 for an oil spill in the Tauranga Harbour last year.

Representatives of the company appeared in Tauranga District Court today for the company's sentencing after it pleaded guilty on December 22 to spilling about 1.5 tonnes of heavy fuel oil into Tauranga Harbour on April 27, 2015.

Oil being cleaned off rocks following the 2015 oil spill.

A reporter in court says 90 per cent of the $288,000 has been ordered to go to the Bay of Plenty Regional Council.

EARLIER:

Mobil Oil New Zealand is in Tauranga District Court today to be sentenced in relation to an oil spill in Tauranga Harbour last year.

A reporter in court says the judge is hearing from both the Bay of Plenty Regional Council and Mobil, before he moves onto sentencing the company.

The Bay of Plenty Regional Council laid charges against Mobil following the fuel oil discharge to Tauranga Harbour in April 2015.

Mobil Oil NZ pleaded guilty on December 22 to spilling about 1.5 tonnes of heavy fuel oil into Tauranga Harbour on April 27, 2015.

A small hole in a spur line off the main under-wharf bunker line leaked oil on ANZAC weekend.

Carried by wind and the tide, the slick polluted the Tauranga Bridge Marina, as well as the upper harbour at Maungatapu.

Clean up costs are said to be $1.79 million. Mobil took responsibility for the spill after a visual inspection of a corroded pipe indicated that the fuel oil leak occurred from two holes in a 150mm diameter lateral pipeline.

'Mobil apologises for the incident and for the impact it had on the community and the local environment,” says Mobil country manager Andrew McNaught.

'Our priority has always been to minimise the impacts to the local environment and to ensure a thorough clean up and restoration of affected areas in Tauranga Harbour,” he said.

The company worked cooperatively with the BOPRC to actively assist in the response and investigation.

Mobil has paid $1.8 million in reimbursements and other costs, including reimbursing BOPRC almost $1.2 million for costs incurred in the clean-up.

'Mobil learns from all incidents and uses the information to reinforce our commitment to continued improvement. We have already made changes to further improve our operations at Mt Maunganui,” says Andrew.

The effects of the spill took months to clean up with teams of overall clad workers a common sight as they cleared contaminated vegetation from the upper harbour, and then painstakingly hand cleaning every oil covered rock in the Tauranga Bridge Marina intertidal zone.

Oil residue was still being cleared from the Bridge Marina pontoons in August.

The oil worked its way into the seagrass growing between the floats, the pontoon sections. Each berth had to be boomed off in both directions and the gaps water blasted.

The bridge marina and associated Bridge Marina Travel lift were the two businesses that took the direct impact of the stream of heavy fuel oil that flowed southwards from under the Mount Maunganui wharf.

Between 100 and 130 boats had to be cleaned and berth holders' fouled mooring lines replaced.

The Anzac weekend oil spill is the largest Tier 2 oil spill in New Zealand, because of the time it's taken to clean it up, and the escalating cost of that clean-up, says Tauranga NZ First MP, Clayton Mitchell.

'In fact, the size of the spill, the time taken to clean and the associated costs are all so much, that we could correctly classify the spill as a Tier 3,” says Clayton.