BERLIN — An unidentified and highly toxic substance in the Oder River, which flows through Poland and Germany, appears to be responsible for mass fish deaths, Germany's Brandenburg State Ministry for the Environment said.
An analysis of river water sampled this week showed evidence of "synthetic chemicals that may also have toxic effects on vertebrates," the ministry said Thursday. It is still unclear how the substance got into the water, he added.
State laboratories detected high levels of mercury in water samples, according to local broadcaster rbb.
The head of Poland's national water management authority told private broadcaster Polsat News that the presence of mercury in water had not yet been confirmed.
"At this time, these are reports. We have not confirmed that oder contains mercury," said Przemyslaw Daca, director of Polish waters.
The Ministry of Brandenburg, the province around Berlin, said it was not yet possible to estimate the number of dead fish in Poland and Germany.
"In this case, the lines of communication between the Polish and German sides failed," Brandenburg Environment Minister Axel Vogel said, adding that German authorities have not yet received notification of the incident from Poland. added.
In a public warning this week, residents of the Uckermark and Barnim districts, with their rolling hills and nature reserves, were advised to avoid contact with water from the Oder and adjacent canals.
In Poland, a senior local official of the opposition Citizen's Platform Party said it would submit a motion to declare a state of natural disaster in the Lubusz region. The decision to do so rests with the government.
"Under no circumstances should the Oder River be approached or watered by animals," Anna Elzbieta wrote on Twitter. (Reporting by Anna Wlodarczak-Semczuk; writing by Rachel More; editing by Hugh Lawson and Mike Harrison)