Mysterious fish death: what findings say about Oder river poisoning

The plight of the poisoned Oder – Poland’s second longest river, much of which forms the border with Germany – has dominated the news.
But while the scale of the disaster is enormous – with tonnes of dead fish now reported along most of the river’s length – the public remains in the dark as to the causes and possible long-term impact.
While details are still murky, the tragic end result is crystal clear: the Oder has suffered a major environmental disaster, resulting in over 80 tonnes of dead fish being hauled out of the water and the authorities issuing a ban on entering the river and using its water for any purpose.
The rebuilding of the ecosystem will take years, if not decades, environmentalists say.
Where and when did the disaster occur?
Around 27 July, local anglers in the town of Oława observed dead fish in a lock on the Oder and linked their presence to earlier reports – from around mid-July – of similar sightings not far up the river, near the junction of the Oder and the Gliwice Canal, an artificial waterway linking the industrial region of Upper Silesia with the now-poisoned river.
Since then, however, the regional environmental inspectorate in Katowice and the regional Gliwice branch of WodyPolskie – the state manager of Poland’s waters – have denied that the incident in the canal and the fish die-off in the Oława had the same underlying cause.
Meanwhile, what began to look clearly like a toxic wave continued to flow downstream, with reports of dead fish multiplying from ever more locations. On 5 August, the pollution reached Głogów; on 9 August, KrosnoOdrzańskie; then on 10 August, KostrzynnadOdrą, a town early on the section of the river that Poland shares with Germany.
By 12 August, the disaster had reached the Lower Oder, which only heightened the worries of environmentalists, as the region is a particularly valuable area in the river’s valley (more on that below).
The authorities have since put up barriers to stop dead fish from going further downstream.
What findings say?
Early water samples did point to mesitylene poisoning, but that is yet to be confirmed or ruled out definitively. There are still no other details of the water samples taken by the Polish authorities (they are expected on Tuesday at the earliest.
Poland has denied earlier claims reported by the German media that the samples taken by the German environmental services contained mercury.
“We received official water test results from the German side. No mercury was found. Analyses on both sides of the border point to high salinity. Comprehensive toxicological studies are underway in Poland,” Poland’s climate and environment minister Anna Moskwa tweeted on 13 August.
Axel Vogel, the environment minister of the German state of Brandenburg, offered more nuance, as he reportedly told a press briefing in the town of Lebus that “mercury accumulates slowly and was not introduced into the Oder in such a dimension that it could have triggered these deaths immediately”.
The abnormal salinity – which measurements from the German monitoring station in Frankfurt (Oder) point to – is an environment in which toxic cyanobacteria could flourish, says Sebastian Szklarek, a hydrologist.
“If the problem began downstream from the Gliwice Canal – which runs through some of Poland’s most heavily industrialised areas – then it could have originated after somebody – an industrial company or a mine – discharged vast amounts of highly salinated water. That could have led to the flourishing of cyanobacteria,” says Szklarek.
The expert adds that reports of skin irritation – a typical symptom of coming into contact with cyanobacteria – in people working in the Oder to clean it of dead fish make the hypothesis even more likely.
Environmentalists and local residents along the Oder accuse the government and its agencies of sitting waiting far too long after the first reports of fish dying between the Gliwice Canal and Oława in late July.
The agencies involved – mainly the General Environmental Protection Inspectorate (GIOŚ) and WodyPolskie – have sought to refute the accusations by publishing documents or statements claiming they took action already in late July.
Still, the facts are that – whatever caused it – the toxic wave flowed for much of the Oder’s length and reached the valuable Lower Oder region, the Oder’s estuary into the Szczecin Lagoon (ZalewSzczeciński) and the city of Szczecin.
On Thursday, a botched press briefing by Jacek Ozdoba and GrzegorzWitkowski – deputy environment and infrastructure ministers respectively – saw angry locals shout down the officials, who tried to convince them that the situation was under control.
Public pressure has worked to an extent. “We want to find those guilty of this scandal, this ecological crime on a huge scale, and punish them as severely as possible!” Poland Prime Minister Mateusz Morawiecki wrote on Facebook.
He then fired the head of WodyPolskie, PrzemysławDaca, and the head of GIOŚ, MichałMistrzak, saying that the response to the disaster “could have been faster”.
The government also said that a reward of one million złoty (€215,000) is on offer for tipping authorities off about who is responsible for the disaster.
Early into the crisis, the government of the German state of Brandenburg accused Poland of failing to trigger communication protocols and inform the German side of an ongoing crisis on the Oder. Since then, Moskwa has met with her German counterpart Steffi Lemke to discuss the situation and ways of remedying it.
“We have agreed to ensure a close exchange of information between the Polish and German sides. We agree that the priority now is to limit the damage, protect the population and identify the cause and the potential perpetrator. This environmental crime must be solved,” Lemke said after meeting Moskwa.
That said, Lemke told RBB24, a German broadcaster, on the following day that “you shouldn’t try to turn rivers into waterways or sewers”, a swipe at Poland’s plans to make the Oder navigable for goods transport.
“It is certain that German-Polish cooperation did not work in this case. The German side was informed much too late,” Lemke added.
What’s at stake for the environment?
The Oder is, environmentally speaking, valuable as a whole – with Natura 2000 and other forms of nature protection covering much of its length in the Czech Republic (where the river originates), Poland, and along the Polish-German border.
Activists say that the disaster on the Oder is not just a single case of some industrial plant possibly discharging toxic waste into the river. It is the result of years of disregard for the river’s environment.
“It’s far more complex, no matter how much we’d like to pinpoint a single culprit,” says Marta Jermaczek-Sitek, a biologist.
“Water parameters in the Oder have been improving lately…yet people regularly raised alarm over illegal discharge of industrial wastewater. The discharges would typically become diluted but the Oder is very low this year,” she adds.
Indeed, a hydrological map of Poland by meteorological service IMGW – which publishes data from water level-measuring stations – shows the Oder’s course dotted with black triangles indicating low water levels.
Jermaczek-Sitek adds that any works in the river that might have stirred up sediment could have added to the deadly pollution.
“We don’t know all the details but we can sum the whole situation up: the river simply broke down,” says the biologist. “The river’s capacity for self-regulation and self-cleaning reached its limit and an ecological bomb was set off.”