Toxic algae responsible for 300 tons of dead fish in the Oder on the German-Polish border: “A man-made environmental disaster”

That’s what Germany said on Friday Mass fish kills in the Oder were a “man-made environmental disaster” resulting from toxic algae growth triggered by the introduction of salt into the waters.

Presenting a report on the disaster, which saw at least 300 tons of dead fish pulled from the river in Germany and Poland this summer, Germany’s Environment Ministry said the most likely cause was “a sudden increase in salinity”.

The “salt that was brought in” led to a “massive increase in brackish water algae that are poisonous to fish,” it said.

However, the experts had to “leave open the causes of the unnaturally high salt content due to a lack of available information,” it said.

Federal Environment Minister Steffi Lemke said it was clear “human activities” were to blame.

Polish authorities published a separate report on Thursday that also blamed toxic algae for the fish kill. More than 500 firefighters participated in efforts to clean up chaos on the Polish side of the river that summer.

However, the Polish report said the disaster was most likely caused by poor water quality resulting from high temperatures and very low water levels during the summer.

Poland and Germany have long been at odds over the disaster.

Berlin initially accused Warsaw of not communicating the issue, while Poland criticized Germany for spreading “fake news” about the discovery of herbicides and pesticides in the water.

A report by German magazine Der Spiegel on Friday accused Polish authorities of failing to work with their German counterparts to investigate fish kills.

The head of the investigation, Lilian Busse, was quoted as saying that Polish authorities had become “more and more reserved, sometimes almost silent.”

The Spiegel report said Greenpeace investigations had shown that high salt levels at a copper mine in the town of Glogow may have contributed to the disaster.

“It is obvious to me that the Polish government wants to cover up the causes of the fish deaths in the Oder,” Ralph Lenkert, environmental spokesman for the left-wing party Die Linke, told the magazine.

In August, BUND water politician Sascha Maier told CBS News that it wasn’t just fish that were affected. Many other animals, including mussels and small vertebrates in and around the river, also suffered, Maier said.

The ecosystem has already been under a lot of stress this summer, Maier told CBS News, thanks to extreme heat and little rainfall. These conditions have most likely at least exacerbated the problem, as the lower volume of water means a higher concentration of toxic substances present.

“Because of the low water, we have a warm Oder,” he said. That alone can lead to considerable physical stress for many fish species, “if dirt is added to this, they are less resistant”.

Anna Noryskiewicz contributed to this report.