Ohio's Cuyahoga River, a polluted mess that has caught fire at least 10 times since the late 1800s and is notorious for erupting into flames in 1969, now supports more than 60 species of fish, as well as beavers and birds, in places that were once all but devoid of life. The exact cause of the 1969 fire was unconfirmed, but people believe sparks from a passing train ignited an oil slick in the river.
Few environmental regulations existed in the late nineteenth century. Cleveland was already known as a polluted manufacturing center at that time, largely due to a booming steel industry. The 1969 incident is credited with building momentum for the passage of the Clean Water Act in 1972 and the establishment of the Environmental Protection Agency, both federally and in the state of Ohio.
The Ohio EPA worked to clean up the river in the following decades, and the water quality has improved dramatically--so much so that in 1998, Cuyahoga was recognized as one of 14 American Heritage Rivers. However, problems like urban runoff and sewer overflows continue to trouble local waterways.