Authorities in Poland and Germany are still searching for the reason behind the deaths of thousands of fish in the Oder river, almost a month after locals discovered the first signs of the ecological disaster.
They have discovered some details that could soon shine a light on the mystery. Satellite imagery has detected increased chlorophyll concentrations in the river that runs along the German-Polish border, suggesting an algae bloom, which could cause oxygen deficiency.
The German region of Brandenburg's Environment Ministry reported elevated pesticide levels, which the Polish side denies, as well as increased salinity of the water. In contrast, Poland's water authority reported 282 unauthorized wastewater inflows into the river.
"There are several organic and inorganic substances that may be responsible,” said Andreas Kübler, spokesperson for the German Environment Ministry.
“It really seems to be a chemical cocktail ... None of these substances alone has led to the fish kill, according to our findings so far."
However, a spokesperson for Germany’s Environment Ministry stressed that there could be multiple reasons behind the deaths.
“The search for the causes of the fish die-off in the Oder still haven’t been completed,” said Andreas Kuebler said. “So far we have several organic and inorganic substances that could be responsible.”
“It seems to be a cocktail of chemicals,” he added. “According to our information so far, none of these substances alone led to the fish die-off. It must still be assumed that this could be a multi-causal incident.”
At the end of July, the first signs that the fish were dying were discovered in Poland.
German authorities have accused the neighbouring country of waiting too long to inform them of the deaths, making it difficult to investigate the causes. Nearly 200 tonnes of dead fish have been removed from the River.