A while ago I was editing an article about the history of the city of Cleveland--Yes, exciting, I know--when I came across the following statement.
"As an industrial city, Cleveland had always experienced problems related to pollution. The city hit a low point, however, in the summer of 1969 when the Cuyahoga River, which flows through the city, caught fire."
The state of the river is evocatively described in this TIME article from 1969.
Today I came across two articles in the New York Times which made me happy. The first is from the twentieth anniversary of the fire in 1989, and is titled "River Not Yet Clean, but It's Fireproof".
The second was published today, on the occasion of the fortieth anniversary of the fire, with the less funny but more optimistic title "From the Ashes of ’69, a River Reborn".
I've not really got anything to add to this, I just thought I'd link some interesting articles.