Anna Moskwa made the announcement at a news conference on Tuesday, Polish state news agency PAP reported.
She told reporters there were several hypotheses as to the causes of the mysterious mass die-off of fish in the Oder, a river that also flows through Germany.
According to Moskwa, the environmental disaster may have been caused “by a toxic substance entering the Oder; by unfavourable natural conditions; by a large amount of industrial wastewater being dumped into the Oder, causing notable salinisation of the river; or by a combination of hypotheses two and three.”
‘No toxic substances in water samples’
Moskwa said: “The Main Environmental Inspectorate (GIOŚ) has analysed water samples and none of them contained any toxic substances.”
She added that the agency was also probing "hypothesis two, namely that natural conditions were to blame for the disaster, such as high temperatures, low water levels and rising pollution levels."
Authorities were also “checking the validity of hypothesis three, that a large amount of industrial wastewater, full of chlorine, was dumped into the Oder,” she told reporters, adding that "a combination of hypotheses two and three" was also possible.
‘No pesticides in dead fish’
Moskwa announced that "so far none of the species of dead fish under investigation has been found to contain pesticides.”
She said: “The radionuclide levels are below norm and no connection has been found between radionuclides and the die-off of fish.”
She added that the fish were also being subjected to a range of other analyses, "including histopathological analysis," the PAP news agency reported.
Poland to create ‘advanced system for constant monitoring of surface waters’
Moskwa told reporters that, in the wake of the Oder River disaster, the government "made a decision to take a comprehensive approach to the monitoring of Polish waters.”
“Our aim is to create an advanced system for the constant monitoring of surface waters, together with an early-response system for potential crises, emergencies and disasters,” she told the news conference.
Meanwhile, the Main Environmental Inspectorate said on Tuesday that the condition of the Oder was “stabilising,” with key parameters “returning to typical levels for this time of year,” although “the salinisation levels are still high,” the PAP news agency reported.
(pm/gs)
Source: PAP, rp.pl