A general view of Oder river banks, where dead fish float, as water contamination is believed to be the cause of a mass fish die-off, in Kostrzyn nad Odrą, Poland, August 12, 2022. REUTERS/Lisi Niesner

A member of the Polish Armed Forces reacts as they remove dead fish from the Oder river, near the German border, as water contamination is believed to be the cause of a mass fish die-off, in Slubice, Poland, August 12, 2022. REUTERS/Lisi Niesner TPX IMAGES OF THE DAY

A pier with a note "No entry" is seen as dead fish float in the Oder river at the border with Germany as water contamination is believed to be the cause of a mass fish die-off, in Kostrzyn nad Odrą, Poland, August 12, 2022. REUTERS/Lisi Niesner

Dead fish are removed from the Oder river as water contamination is believed to be the cause of a mass fish die-off, near the border with Germany, in Krajnik Dolny, Poland, August 15, 2022. REUTERS/Lisi Niesner

Dead fish float on the surface of the Oder river, as water has been contaminated and is causing the mass extinction of fish in the river, in Kostrzyn upon Oder, Poland, August, 11, 2022. Cezary Aszkielowicz/Agencja Wyborcza.pl via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. POLAND OUT. NO COMMERCIAL OR EDITORIAL SALES IN POLAND. REFILE - CORRECTING CITY

A member of the Polish Armed Forces removes dead fish from the Oder river, near the German border, as water contamination is believed to be the cause of a mass fish die-off, in Slubice, Poland, August 12, 2022. REUTERS/Lisi Niesner

A note on the fence warns against danger of a possible water contamination of Oder river at the border with Poland in Lebus, Germany, August 15, 2022. REUTERS/Lisi Niesner

Dead fish float on the surface of the Oder river, as water has been contaminated and is causing the mass extinction of fish in the river, in Kostrzyn upon Oder, Poland, August, 11, 2022. Cezary Aszkielowicz/Agencja Wyborcza.pl via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. POLAND OUT. NO COMMERCIAL OR EDITORIAL SALES IN POLAND. REFILE - CORRECTING CITY

Dead fish are removed from the Oder river, as water contamination is believed to be the cause of a mass fish die-off, by the German border, in Krajnik Dolny, Poland, August 13, 2022. REUTERS/Annegret Hilse

A dead fish lies on the bank of Oder River on the German-Polish border, in Brieskow-Finkenheerd, Frankfurt (Oder), Germany, August 11, 2022. REUTERS/Annegret Hilse TPX IMAGES OF THE DAY

Dead fish float on the surface of the Oder river, as water has been contaminated and is causing the mass extinction of fish in the river, in Bielinek, Poland, August, 11, 2022. Cezary Aszkielowicz/Agencja Wyborcza.pl via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. POLAND OUT. NO COMMERCIAL OR EDITORIAL SALES IN POLAND.

Dead fish are removed at a mobile catch basin from the Oder river, as water contamination is believed to be the cause of a mass fish die-off, by the German border, in Krajnik Dolny, Poland, August 13, 2022. REUTERS/Annegret Hilse

Dead fish float in the Oder river at the border with Germany as water contamination is believed to be the cause of a mass fish die-off, in Kostrzyn nad Odrą, Poland, Poland, August 12, 2022. REUTERS/Lisi Niesner

Dead fish floats on the surface of the Oder river, as water has been contaminated and is causing the mass extinction of fish in the river, in Bielinek, Poland, August, 11, 2022. Cezary Aszkielowicz/Agencja Wyborcza.pl via REUTERS ATTENTION EDITORS - THIS IMAGE WAS PROVIDED BY A THIRD PARTY. POLAND OUT. NO COMMERCIAL OR EDITORIAL SALES IN POLAND.

Dead fish are removed from the Oder river, as water contamination is believed to be the cause of a mass fish die-off, by the German border, in Krajnik Dolny, Poland, August 13, 2022. REUTERS/Annegret Hilse

German Environment Minister Steffi Lemke visits a bank of Oder River to get informed about the mass fish die-off crisis by workers of the emergency services of a firefighters brigade, the Federal Agency for Technical Relief (THW), a water rescue service and the German Red Cross (DRK) in Frankfurt (Oder), Germany August 13, 2022. REUTERS/Annegret Hilse

A dead fish floats on the surface of the Oder River on the German-Polish border, in Brieskow-Finkenheerd, Frankfurt (Oder), Germany, August 11, 2022. REUTERS/Annegret Hilse

A dead fish is removed from the Oder river as water contamination is believed to be the cause of a mass fish die-off, near the border with Germany, in Krajnik Dolny, Poland, August 15, 2022. REUTERS/Lisi Niesner TPX IMAGES OF THE DAY

FILE PHOTO: Dead fish are removed from the Oder river, as water contamination is believed to be the cause of a mass fish die-off, by the German border, in Krajnik Dolny, Poland, August 13, 2022. REUTERS/Annegret Hilse/File Photo

Dead fish are removed from the Oder river at a mobile catch basin, as water contamination is believed to be the cause of a mass fish die-off, by the German border, in Krajnik Dolny, Poland, August 13, 2022. REUTERS/Annegret Hilse TPX IMAGES OF THE DAY