While the ongoing drought has caused some of Europe’s major waterways, like the River Rhine, to almost completely dry up over the last weeks, another environmental disaster— the reason of which is still not completely known—has struck the River Oder and caused more than 100 tonnes of fish to die. Out of caution, authorities have issued a ban on entering the river. While the search for the reason behind the disaster is turning political in the media, environmentalists are predicting that the rebuilding of the ecosystem might take years, if not decades.
The River Oder is Poland’s second largest river and runs through large parts of Poland’s industrial region in the Southwest before forming the border with Germany in the West and emptying into the Baltic Sea. On July 27th, anglers first discovered dead fish near Oława, close to the industrial centers in Wrocław and Katowice. While no clear reason for this could be found, what had been referred to as a “toxic wave” of dead fish continued to flow downstream, which led to increasing sightings of more and more dead fish along the way. By August 12th, the poisoned fish had reached the Lower Oder, where authorities had installed barriers to prevent the fish carnage from floating further downstream.
Despite the disaster being documented for almost a month now, there is no clear sign of what lies behind it as of yet. The initial assumption was that toxic poisoning from sewage or pesticides might be the reason, but neither the tests of the water nor the analysis of the dead fish pointed to excessive amounts of these pollutants. Also, radiation levels were within the normal range.
What has been found, however, was the presence of toxic “golden algae” in the water of the Oder, which is now considered to be one of the more likely reasons for the ecological disaster. Polish Minister of Environment Anna Moskwa said in a statement that the bloom of the algae “can cause the onset of toxins that kill fish and mussels.” While these algae usually only appear in brackish water, they also need a high level of salinity to thrive, which exceeds the natural levels in the Oder. But according to investigations by the German State Office for the Environment in Frankfurt an der Oder (over 600 km northeast of Frankfurt), tests in recent weeks have shown “unnaturally high loads of salt” being measured at the official gauging station. At the time of this writing it is unclear whether this alone could have caused such a disaster; increasingly, experts are considering multicausality behind the breakdown of the ecological system in the Oder.
Another theory purported in German media was that mercury had been found in the water of the Oder, which led to outrage amongst Polish officials. Anna Moskwa called out German media for “spreading ‘fake news’,” which in turn caused the spokesman of the German Ministry of Environment Andreas Kübler to be “surprised and saddened by Warsaw’s suggestion that Germany was spreading ‘fake news’.”
Meanwhile, the opposition in Poland accuses the government of inactivity and responsibility for this environmental disaster. “The authorities have failed us. This is not just an environmental disaster, it is a disaster of the Polish state,” according to Krzysztof Smolnicki from the activist group Smog Alarm.
As the investigation into the causes of the disaster continues, the Polish government has put out a reward for any information leading to finding the root of the problem. At the same time, the governor of West Pomerania, Zbigniew Bogucki had 21 aeration pumps dispatched to mix the river water with as much air as possible, as the lack of oxygenation is considered to be a likely cause of the fish dying. Bogucki reported that in places where the pumps are operating, the situation is improving, but that it may not be enough to “reverse these adverse conditions related to the lack of oxygen.”