Poland battles toxic algae as tons of fish die in Oder basin

Warsaw, Poland — Poland has taken steps to contain the spread of toxic golden algae in the river Oder's tributary system to prevent a repeat of the pollution crisis that hit the waterway in 2022, the climate ministry said Sunday. 


Hydrogen peroxide has been pumped in at the junction of the Gliwice Canal and the Klodnica river, helping to reduce the algae by over 90%, the ministry said in a statement. 


Between Aug. 3 and 16 some 77 tons of fish have died in the affected section of the canal and in nearby lake Dierzno Duze. The risk related to the algae remains critical in the canal, it said. 


"We emphasize that the use of hydrogen peroxide is a crisis measure, not a systemic one," the ministry said. 


The main cause of golden algae growth is saline water discharged by the mining industry into the rivers. Poland is working on a plan to build desalination installations. 


In the summer of 2022, hundreds of tons of dead fish were found in the Oder, which runs along part of Poland's border with Germany. Smaller amounts of dead fish have been found in the river and its tributaries on several occasions this year.