2022 Oder environmental disaster

During the summer of 2022, a mass mortality event involving fish, beavers, clams, crayfish and other wildlife occurred in the Oder river.

Over 100 tonnes of dead fish were removed from the Polish section of the river, and a further 35 tonnes from German sections, causing concern that the water was poisoned.

At first the cause was not clear, theories included the effects of the summer heat and lower water levels due to the European drought, reduced oxygen levels due to the heat and nutrient loading, a spike in oxygen levels due to the introduction of an oxidizing agent, and pollution by chemicals including mercury, mesitylene, salts or other sewage, as well as the possibility of an algal bloom. It was later determined that an algal bloom, which was made possible by the discharge of saline industrial wastewater into the river on the Polish side, is the probable cause of the disaster.

The Polish authorities were slow to react, causing a scandal and resulting in the dismissal of officials responsible for water management and environmental protection. A reward of 1 million zlotys (about €222,000, as of September 2023) was offered for information about possible culprits.

Background

The Oder flows through the city of Ostrava, across the Czech–Polish border, terminates the Gliwice Canal, passes through Lower Silesia including the city of Wrocław, and farther forms the German–Polish border until it flows into the Baltic Sea. It is engineered to carry heavy barge traffic.

Decades ago, the Oder river was extremely polluted before reaching Wrocław due to the heavy industrialization in Ostrava, Upper Silesia (connected through the Canal and the Kłodnica river having many large coal mines around), and Lower Silesia. Large chemical factories are in Kędzierzyn-Koźle at the Canal.