Europe’s Black Seas

Disastrous discharge of oily wastewater continues despite monitoring

Big battles have been won against ships illegally dumping oily wastewater. But the fight isn’t over. This investigation estimates that 3,000 vessels discharge mineral oil into European waters annually – the equivalent to eight spills per day, each the size of 750 football fields.

Bilge dumping is the name given to the release of untreated oily waste-water produced by vessels onto the sea. As well as oil it contains hazardous metals and chemicals – a potential environmental crime.

The European Maritime Safety Agency (EMSA) has spent millions of euros creating an elaborate system, CleanSeaNet, that aims to monitor and prevent bilge dumping at sea using radar technology. But despite the EU taxpayer money invested into the system, their detailed reports have not been made public.

We set out to know what was happening in partnership with the environmental watchdog Skytruth. We detected hundreds of potential bilge dumps in European waters since mid-2020.


Using satellite imagery and machine learning provided by the environmental watchdog SkyTruth, we found hundreds of potentially illegal oil dumps by shipping vessels and oil tankers in European waters since 2020.

Although control over bilge dumping has increased significantly over the last decade, sources we spoke to – including environmentalists, port officials and members of shipping crews – admit that bilge dumping remains a reality in European waters.

We spoke to six whistleblowers who confirmed the structural nature of the phenomenon and gave us an insight into how they circumvent the system: using specific pumps, falsifying oil logbooks, or discharging at night when radar technology can detect it, but not easily verify the dump.

A culture of fear has discouraged people from speaking out: one person we spoke to, had been detained onboard his vessel for over 10 days when he refused to discharge oily water. Another source told us they had been fired three months into their contract for speaking out about illegal bilge dumping.

The European Maritime Agency has spent millions creating a CleanSeaNet to monitor and prevent bilge dumping at sea using AI and radar technology. The system is smart, but toothless as it relies on member states for enforcement. FOIA requests showed how response rates vary widely between EU member states, but are generally low. Data from 2019 demonstrated that only 1.5% of all potential spills are verified by member states within a critical three-hour time span.

The system is currently under review after an EU commission assessment found it “not optimally used or coordinated.”


After working hours, inside small cabin rooms and with limited internet access, whistleblowers spoke of being intimidated by their employers. One seafarer told us he was threatened the moment he set foot on the ship he worked on, almost two years ago: “He (the chief engineer) immediately told me: this is how we do it, because there is too much water, we cannot do anything. Be quiet, do not speak out, if you speak then it is very much trouble for you.” The seafarer’s contract was terminated immediately after confronting the engineer about discharging oily waste-water.

Despite being a punishable crime in Europe, accountability for bilge dumping remains scarce. Slow response times by national authorities and limited public data have allowed impunity for offenders. Even if member states identify bilge dumps, they are not required to disclose what action is taken. Experts told us enforcement of fines are sporadic, and often are not high enough. “Even if an oil sample is taken after the fact and they find out which ship the oil came from, the likelihood of the polluters being fined a large amount is minimal,” said Christian Bussau, a marine biologist with Greenpeace. “There is still a certain incentive, for cost reasons, to illegally dump oil at sea.”

Bilge dumps don’t garner the same visibility as large oil spills. They are less visible, and smaller in scale, but the frequency at which they are happening should be cause of concern. One ecotoxicologist at the Swedish Environmental Research Institute told us maritime oil pollution has direct toxic effects on small marine organisms.

Inside the maritime industry and amongst port officials, bilge dumping remains an open secret. One high-ranking officer inside Barcelona’s port – speaking on condition of anonymity – told us it was common practice for bilge dumping to happen in border areas in an attempt to evade fines. In addition, the number of inspectors throughout Spain has been in steep decline in recent years. One spokesperson for Spain’s national maritime authority acknowledged they were not able to verify every alert sent by EMSA.

Whether it is a lack of resources by relevant national authorities, or flaws in EMSA’s accountability system, bilge dumping remains an uncomfortable and toxic reality in our oceans. “This is a problem that’s been invisible to the public,” said the president of Skytruth, John Amos.

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The Impact

Our investigations don’t end when we publish a story with media partners. Reaching big public audiences is an important step but these investigations have an after life which we both track and take part in. Our work can lead to swift results from court cases to resignations, it can also have a slow-burn impact from public campaigns to political debates or community actions. Where appropriate we want to be part of the conversations that investigative journalism contributes to and to make a difference on the topics we cover. Check back here in the coming months for an update on how this work is having an impact.