World War II era shipwreck could trigger $200m oil spill cleanup

• The RMS Niagara was a large ship that was sunk by a mine during World War II
• Gold bars on the shipwreck were collected but the oil on it has never been recovered
• Maritime NZ has warned the government it could cause an oil spill that may cost $200 million to clean up
• The government agency recommends the shipwreck is surveyed, but the Associate Transport Minister won't commit to it

Documents reveal a World War II era shipwreck could trigger a $200 million oil spill clean up but the government is going against officials' advice to at least do a risk assessment survey.

In June 1940 the RMS Niagara was sailing out of Auckland for Vancouver, Canada, with 349 passengers and crew on board.

It was sunk by Germany in the Hauraki Gulf but decades later its oil has never been retrieved.

Maritime NZ had been recommended since 2019 to survey the Niagara shipwreck to work out how much oil is on it, but successive governments have declined.

New documents released to RNZ reveal it could cost $200 million to clean up an oil spill from the ship and it would cause widespread damage over a large area.

The papers show a two-part survey of the ship would cost just over $13.7 million.

Maritime NZ has said the costs are not insignificant but are "minimal compared with the potentially very high costs associated with a large oil spill".

Associate Transport Minister James Meager told RNZ there were no plans to survey the ship at this stage.

That's despite Maritime NZ having warned that if a major spill occurred the government would face criticism that with plenty of warning the environment had suffered negative effects.

What happened in 1940?

The RMS Niagara's journey to Canada was cut short when it was sunk by mines laid by the German naval cruiser the Orion in the Hauraki Gulf - the first act of war against New Zealand by Nazi Germany.

It sank approximately 20 miles (32km) offshore of the Northland coast and now lies 120 metres below the ocean close to the marine boundary between Northland and Auckland.

In the 1940s and 50s operations were conducted to take 585 gold ingots owned by the UK treasury off the shipwreck - however, they did not remove any oil off it.

As the wreck nears 85 years old and continues to deteriorate, Maritime NZ and the government have been keeping a close eye on the possibilities of a major oil spill.

It is unknown how much oil is on the ship, but Maritime NZ believes it's "furnace oil" which is described as dark, thick and when spilled, would persist in the environment for some time.

The vessel had the capacity to hold 4324 tonnes of oil.

How much would an oil spill cost?

Ministerial briefings revealed to RNZ under the Official Information Act show that in October last year then Associate Transport Minister Matt Doocey was told by Maritime NZ in a briefing the potential cost of a significant oil spill caused by the wreck.

"Detailed economic modelling of the direct costs of a response to a significant oil spill from the wreck was completed in 2020 and assessed that for a spill of 1600 tons direct costs would be in the order of NZ$108 million (approximately NZ$200 million in 2024 prices)."

The agency said the $200 million figure did not include indirect costs, the costs to natural capital and reputational damage.

The same document said that about 27 species of birds breed nearby the wreck which included five that breed exclusively in that area.

One of those birds is the New Zealand Fairy Tern of which there is only 40 individuals left in the population, making them New Zealand's rarest breeding bird.

Maritime NZ said the release if oil from the wreck was likely to cause widespread damage over a wide area in a region with "significant scientific, cultural, economic and reputational value".

How can the government find out how much oil could be on the ship?

Because there is no official word on how much oil could be on the RMS Niagara wreck Maritime NZ have recommended for years to conduct a two-part survey of the wreck.

The agency applied for government funding for the survey in the 2019 and 2020 budgets under the Labour-led government - both were declined.

The first stage of the work would be a visual survey of the wreck to work out its state of degradation.

Information could be captured by visual imagery, video footage, sonar and laser scanning which could be used to generate a 3D model of the wreck.

The second stage would involve the measurement of hull thickness and contents of the vessels available bunker tanks using a technique called neutron backscatter.

In a briefing from 2023 Maritime NZ stated because of the way the wreck is lying many of its fuel tanks are inaccessible meaning that the surveys may not inform a complete risk assessment.

Maritime NZ still recommends that the surveys are conducted.

In October the agency said latest estimates show the total survey costs would be $13,741,000 -- the first stage would cost $1,300,000; the second stage would cost $12,441,000.

The cost of the survey is driven up by the wreck's proximity to the Southern Cross transmission cable which means the work would need to be done by a boat that can do the work without using an anchor.

The cost of that vessel could make up $7.5 million of the survey total.

In the 2023 ministerial briefing it also stated if a significant oil spill eventuated the likely critique will be "with plenty of warning, time to prepare, options to manage the risk, and the environment has suffered avoidable negative effects".

The same paper said there had been reports of oil leaking from the ship in February 2016, May 2019 and August 2023.

How much would it cost to remove the oil?

If through surveying, it confirmed a significant amount of oil was on the boat the government would have to consider how it could remove it.

In the October 2024 ministerial briefing it stated the cost of removal what be dependent on factors such as the location of the wreck and the availability of workers, vessels and equipment.

Maritime NZ said there would likely be significant technical challenges with accessing tanks on the low side of the wreck.

It said when the US National Oceanic and Atmospheric Administration and the US Coast Guard decided to remove oil off a ship of similar age in 2003 it cost NZ$31 million at the time.

That would be $51 million in today's prices; however Maritime NZ noted the ship was only at a depth of 53m, significantly shallower than the RMS Niagara at 120 metres.

The documents said the greater depth would likely increase costs and challenges with any oil removal operation.

What does the government say?

The new Associate Transport Minister James Meager declined a request from RNZ for an interview but provided a statement which said no plans for a survey were in the works.

"The government does not intend to conduct the survey of the Niagara at this time."

Meager said that Maritime NZ remained the lead agency to respond should a significant oil leak occur.

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