Short answers, pulled from the story.
The name Oder derives from ancient Illyrian roots and traces to the term Adra meaning water vein. Claudius Ptolemaios recorded the river as Suebos in his Geographike Hyphegesis around 150 AD linking it to the Germanic people known as the Suebi.
The Oder rises in the Czech Republic before flowing through western Poland for hundreds of kilometers. Eighty-nine percent of its drainage area lies within Polish borders while six percent belongs to the Czech Republic and five percent falls under German jurisdiction.
Under Germania Magna the Romans knew the river as Viadrus or Viadua in Classical Latin. It served as a key branch of the Amber Road connecting the Baltic Sea to the Roman Empire.
At the 1943 Tehran Conference Allies decided that Germany's new eastern border would run along the Oder. In 1990 newly reunified Germany and Poland signed a treaty recognizing the Oder Neisse line as their official border.
On the 11th of August 2022 authorities discovered the Oder river had been contaminated with dead fish washing ashore. At least 135 tonnes of dead fish appeared on its shores during this event following water samples taken on the 28th of July indicating possible mesitylene contamination.