Oder mass fish deaths: Searching for clues to Polish-German border mystery

The men in waders lay the dead fish on a tarp on the riverbank as they looked solemn.

The faces of the people were masked against the nauseating smell for eight days. One worker said that he felt numb.

Fish are dying on the River Oder.

Between Poland and Germany lies the river. Experts from both countries have been unable to come up with a solution to the problem. There are hundreds of tons of dead fish.

Scientists think someone polluted the water with a substance that made the water salty. The golden algae flourished. It killed the fish. The water quality was affected by the rotting corpses.

They say a chemical chain reaction may have been caused by a hot summer and low river levels. They haven't identified the original pollutant.

It will be hard to get a clear answer to what happened. He and his team were testing the water on a small boat.

There is an ecological disaster in Poland. It is a disaster. We have never seen so many dead animals. It is the first time it has happened and it is a serious warning.

Near the city of Gliwice, hundreds of miles up the river, Ewa Sternal looks out over the boats bobbing in a small marina and says she saw it coming.

The marina is located within a port. She explains that the water in the Oder comes from the Gliwice canal.

The people reported fish dying and the water changing.

The fish appeared to try to get out of the port by gathering near its entrance. She started to investigate after it happened again in June.

The pollution got into the water directly here. I spoke to many people. Someone dumped chemicals into the port.

Which one? There is still no evidence on Polish industry and Polish mines.

More than 200 people have been interviewed by police. There is a large reward for information that leads to the arrest of a criminal.

Fishermen near Gliwice told us they saw fish dying in March, but they didn't think anyone would be caught. Someone is responsible, someone is to blame, but we won't find out who.

More than 300 unlicensed outflow pipes have been discovered and investigators are looking at 60 of them.

Image source, Brockmann Consult

There were errors in the handling of the case. They were too slow to react to signs of a problem. There was a spat between the Polish and German authorities.

The way the river is used needs to be reviewed by experts. They are worried that it could happen again if the original source of pollution isn't found.

He wants an online monitoring system that will inform the authorities much more quickly. There is a need for a quicker response.

Fish are dying. The corpses were sent for cremation.

A pump is trying to get oxygen into the water as workers drag dead fish from the river. The river goes into a lagoon and onto the Baltic Sea.

It is hoped that the sheer amount of water will cause the toxins to be diminished, but there are concerns that the poison will continue down the river.

Lukas Potkanski is from the Polish Fishermen's Association. The healthiest water has to be mixed with the most poisonous water.

The fish recovered here were sometimes 20 or 30 years old according to Lukas.

He thinks life will come back to the Oder. It will be a long time before the river's health is restored.