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Cargo ships dumping oil into the sea go unpunished

Max Bernhard | Julia Bayer | Nina Werkhäuser
March 22, 2022

Vessels continue to pollute the world's oceans with oily wastewater. A DW investigation shows how seafarers circumvent environmental laws to save time and money, with devastating effects.

Ship stacked with multicolored cubes and flanked by two smaller boats on North Sea
Global trade is fueled by tens of thousands of merchant ships that are at sea every dayImage: Sina Schuldt/dpa/picture alliance

Nothing he had learned at his naval college had prepared the young marine engineer for what he encountered at sea: not for the toxic culture in which superiors bullied and abused junior crew members with seeming impunity, nor for the indifference with which seafarers treated the very oceans that earned them a living — illegally dumping contaminants into the waters without a second thought. 

The engineer told DW that at first he was worried, sad even, as he witnessed how oily wastewater was routinely illegally dumped into the ocean from the giant tanker he worked on. But, as the pollution continued, he soon grew numb to it. "Now, I've just accepted it — I know it sounds sad, but ..." he trailed off.

Satellite imagery and whistleblowers expose oil spills

Dumping oily wastewater into the ocean has been outlawed globally for decades, but an investigation by DW, in collaboration with the European nonprofit newsroom Lighthouse Reports and eight other European press outlets, has found that the practice is still common today, with potentially devastating effects for the environment.

During the monthslong investigation, DW and its reporting partners talked to several whistleblowers and experts, who described a cat-and-mouse game in which seafarers use different techniques to bypass pollution safeguards and try to avoid detection by the monitoring technology employed by some governments.

Satellite imagery and data provided by the environmental group SkyTruth helped identify hundreds of potential dumps across the globe in 2021 alone. But the number of spills is most likely significantly higher because the satellites used by SkyTruth cover less than one-fifth of the world's oceans. According to the group's estimate, the amount of oily water dumped into the oceans this way could amount to more than 200,000 cubic meters (52.8 million gallons) annually, or roughly five times the equivalent of the 1989 Exxon Valdez spill in Alaska — one of the worst maritime environmental disasters.

Big ships, big profits

Several tons of oily bilgewater per ship

Global trade is fueled by tens of thousands of merchant ships that are at sea every day, transporting everything from oil and luxury cars to smartphones and boxes of cereal. The tankers that transport our goods can measure close to 400 meters (1,300 feet) in length, with engines bigger than coach buses. As the ships make their journeys, liquids from the engine room, oil, detergents, water and other substances collect in the bottom of the vessel, the bilge. This noxious mixture, called "bilgewater," is then stored in tanks. In a day, a single merchant ship can produce several tons of it.

International regulations require that large vessels treat the bilgewater with an "oily water separator" before it is discharged into the ocean. Each liter of bilgewater pumped into the sea after treatment is permitted a maximum residual-oil proportion of 15 parts per million, or 15 milligrams of oil per liter of water (0.0005 ounces per quart), according to a limit set by the International Maritime Organization (IMO) in 1973. The remaining toxic mixture is stored in tanks onboard and later discharged at harbor in port reception facilities.

All big vessels are required to have working separators. But many ships circumvent the system entirely.

'It's very easy' when you use a portable pump

DW and its partners spoke to five whistleblowers with years of experience working on container and chemical cargo vessels who say they have witnessed illegal bilge dumps. All of them requested anonymity out of fear of losing their jobs or being blacklisted for future opportunities.

Whistleblowers such as the people interviewed by DW and its partners are often the only source of information for what happens when a ship is on the water. Though DW was not able to fully verify their accounts, the sources independently corroborated each other in key aspects and provided footage of the incidents they witnessed, as well as other documentation.

Tubes connected to mechanisms to pump bilge water
A photo provided by a whistleblower shows a portable pump used for illegal dischargesImage: Privat

Almost all of the whistleblowers detailed a similar method for bypassing the oily water separator: a small, portable pump. "It's very easy," one man who had witnessed it in operation on several occasions told DW. "You can assemble this portable pump in five minutes and then detach (in) five minutes and hide (it) if someone is coming."

The pump is used to transfer the oily water into a different tank — in most cases, the sewage tank. On the high seas, ships are allowed to dump their sewage untreated. Then, the toxic mix is quietly released into the ocean, often under the cover of night or during inclement weather, when there is a lower chance of getting caught, according to several seafarers DW talked to. At night it is harder for authorities to verify the crime, and bad weather can prevent the deployment of surveillance ships and planes.

"If you were to do this in the English Channel in broad daylight in perfect weather, for example, you'd immediately have the water police on your tail," said Christian Bussau, a marine biologist with Greenpeace, who has been working on oil pollution in the North and Baltic Seas for over 25 years. "But, if ships do it in bad weather, during storms or at night, they have a good chance of getting away unnoticed," he said.

The toxic effects of bilge pollution

Maritime transport has more than quadrupled in the nearly five decades since the IMO arrived at its standard of 15 parts per million for oily-water discharges. Even bilgewater that has been treated to adhere to this legal limit has been found to be toxic to marine organisms, according to research published in 2021 by the Swedish Environmental Research Institute and co-authored by the ecotoxicologist Kerstin Magnusson. She said the current regulation should be reassessed. As global shipping continues to grow, bilge pollution is accumulating.

Oil pollution is a more acute problem than microplastics because it has immediate and direct toxic effects, Magnusson said. The impact of small oil discharges on marine life remains underinvestigated, she added, but academic research suggests that even small oil spills can have lasting harmful effects on marine life when they happen frequently. And repeated spills create a form of chronic pollution that can have severe effects on the environment.

Aside from oil, bilgewater can contain a variety of hazardous substances, including various chemicals, detergents, inorganic salts, and metals such as arsenic, lead and mercury. The substances contained in the bilgewater can damage the microorganisms on which larger animals feed, and enter the human food chain via shellfish and fish.

EU efforts against bilge dumping

Because the illegal dumps happen at sea, it is difficult for authorities and researchers to track them. That is why satellite imagery is used to monitor the seas for pollution. When a vessel discharges oily wastewater illegally, it usually creates a spill kilometers long and with a very distinct shape.

Potential oil slick detected by radar satellite Sentinel 1 on April 13, 2021
Satellites can detect oil slicksImage: Copernicus SentinelHub

A system set up in 2007 by the European Maritime Safety Agency, or EMSA, uses radar satellites to "see" through cloud cover and at night to identify possible spills. It alerts the respective member states when one is found. In some cases, substances such as algae can be mistaken for spills, which is why experts review the imagery. By cross-referencing the location of the spills with ship-location data, EMSA can sometimes identify the possible polluter immediately.

Since its inception, the mechanism, called CleanSeaNet, has detected tens of thousands of possible oil slicks, and statistics show a reduction of illegal dumps in EU waters. But the system has its flaws.

Illegal dumps "still regularly occur in European waters," according to EMSA, and the number of spills detected and prosecuted remains low. Individual member states do not always follow up on the alerts, and, when they do, it is often not quickly enough. The longer it takes authorities to verify a spill in situ, the less likely they are to find oil, as spills begin to dissipate. In 2019, only 1.5% of spills were verified within a critical three-hour time frame. Polluters are only caught in a fraction of cases.

The satellites are also not able to monitor EU waters continuously, meaning that there is a window of several hours each day during which oil spills can go unnoticed. To get a sense of the total scope of this issue in EU waters, SkyTruth combined data and assumptions from EMSA with calculations of satellite coverage. Based on that fairly conservative estimate, the group expects that every year nearly 3,000 slicks are caused by vessels discharging mineral oil into EU waters. That averages out to more than eight per day — the majority of which go unseen by satellites.

Map shows the sites of potential dumps of oily wastewater

Thousands of undetected illegal dumps

EMSA does not make its detailed detections public. But, using the same publicly available satellite imagery that the agency uses, vessel-tracking data and machine learning provided by SkyTruth, DW and its partners were able to identify more than 1,500 potential illegal dumps globally from July 2020 through December 2021. For about 180, it was possible to identify the vessel based on tracking data. These cases include repeat offenders and bilge dumping in protected areas.

DW is not publishing the vessels' names, as the findings couldn't be independently corroborated with visual evidence. The preliminary data by SkyTruth identifies slicks from moving vessels with a high confidence. But the imagery cannot distinguish between mineral oil slicks and those caused by vegetable or fish oil.

Of course, EMSA only monitors the coastal waters of member states. The majority of the world's oceans are not covered by satellites.

Saving time and money with illegal dumps

Because it is so difficult to enforce the law, incentives to dump remain high. Illegally dumping oily wastewater can save a ship significant money. Annual compliance costs can reach over $200,000 (€181,500) depending on the type and age of the vessel and what state it is in. Maintenance of onboard waste-processing machinery such as the oily water separator and disposal fees at ports can be costly, although some countries have started offering free disposal up to a certain amount.

In one case, described by a whistleblower, a leak in the vessel meant that there was too much bilgewater for the oily water separator to process. Finding the leak would have been a time-consuming "headache," which could have reflected badly on the chief engineer.

Often, only a small group of people are privy to the illegal activities: the crew members working in the engine room. Ships are hierarchical, close-knit organizations. Crew members are expected to follow orders and toe the line, no questions asked.

When he joined the vessel, one man told DW, the chief engineer took him aside and told him about the dumping. "He said: 'Be quiet, do not speak out — if you speak then it is very much trouble for you," the man said.

After witnessing several dumps, he confronted the chief engineer, suggesting that the pollution might be illegal. "I said: 'This is wrong,'" the man said. "And he terminated me."

The man was lucky: He managed to find a different vessel. Others who dare to speak out are blacklisted.

Person displays avocado-pit-sized tarball during cleanup operation at Sharon beach
If a lot of oil accumulates in the ocean after big accidents, tar clumps can wash up on beaches. The chronic pollution from illegal bilge dumping is less visibleImage: Jack Guez/AFP

As the chances of getting caught and the fines imposed in some countries are low, rule breakers can gain a significant advantage over their compliant competitors in this tight-margin business.

"The likelihood of the polluters' being fined a large amount is minimal," said Bussau, the Greenpeace marine biologist. "There is still a certain incentive, for cost reasons, to illegally dump oil at sea," he said.

Reward program for whistleblowers

One exception to this is the United States, where a whistleblower reward program has helped prosecute dozens of cases, with fines going into the hundreds of millions of dollars. Penalties in Europe differ greatly depending on the country but are usually significantly lower. In Germany, for example, fines can often be as low as €15,000 ($16,600).

Although the ultimate responsibility for what happens aboard lies with the captain and the ship's operating company, whistleblowers said the dumps often happened without the captain's knowledge. Captains are required to sign the ship's oil record book, a log in which the chief engineer is obliged to record transfers and discharges, but "it's very difficult for [the captain] to assess what is written there or to even understand what is going on in [it]," one of the whistleblowers said.

The oil books are also easy to falsify, according to the whistleblowers and experts, and not always thoroughly reviewed. Even when authorities check the records, Bussau said, "only a fraction of these crimes are detected."

"We unfortunately have many black sheep on the high seas," he said.

Additional reporting by Ayu Purwaningsih and Georg Matthes

3D animation by Martyna Marciniak

Video by Michael Hartlep

Edited by: Milan Gagnon

Max Bernhard DW freelancer
DW's Julia Bayer smiles
Julia Bayer Investigative reporter exposing human rights abuses and environmental crimes.@bayer_julia
Nina Werkhäuser Investigative reporter