The Polish authorities have offered a reward of several hundred thousand euros for tracing the perpetrators of chemical pollution of the river Oder. In Polish and German agriculture, river water may not be used for irrigation for the time being, nor for drinking water in livestock farming. There is also a swimming ban.
Tens of thousands of fish have died in the border river in the past two weeks. There is already talk of an "environmental disaster", although the exact cause is not yet known. Officials say it will take years to recover because the river has been so badly damaged.
The Oder is one of the longest rivers in Europe and has been considered a relatively clean river for years, home to about forty species of fish. Laboratory tests have so far found no mercury, Poland's environment minister said on Saturday. Authorities say the fish may have been poisoned.
Polish Prime Minister Mateusz Morawiecki said "huge amounts of chemical waste" were likely dumped into the river. He promised to do everything possible to limit the destruction of the environment.
Anna Moskwa, the climate and environment minister, said analyzes of river samples taken in both Poland and Germany revealed elevated salt levels. Extensive toxicology studies are still underway in Poland, she said. German Test results have so far not shown a high presence of mercury.
The death of the fish is "atypical," said Axel Vogel, the environment minister of the German state of Brandenburg. He estimates that more than a hundred thousand kilos of dead fish have been removed from the river in recent days in both countries
The death of fish is usually caused by disturbance of the oxygen content when the water level is too low. This is currently the case in Germany and Poland, amid Europe's historic drought. “But we've been noticing an increase in oxygen levels for several days, indicating that a foreign substance has entered and caused all of this,” Vogel said.