[rcooled]

"Scientists also don’t know the exact number of barrels, though a previous estimate suggests there are more than 25,000."

Back in the 19th century, the Chicago River was an open sewer due to becoming a repository for industrial waste and raw sewage that contaminated the city's drinking water and resulted in numerous outbreaks of cholera and typhoid. The river's flow was actually reversed at one point to keep pollution from flowing into Lake Michigan and entering the city's water supply.
The Chicago River is now much cleaner than in the past, but it's still not safe for drinking.