It was the river that first attracted settlers to the Chicago area. But it was the same river that almost killed the city. During the last Ice Age, Chicago was covered by Lake Chicago. When the ice retreated, a 14 foot ridge was left. By the time the Europeans arrived, the Chicago River flowed sluggishly into Lake Michigan.
With the advent of the Industrial Revolution, factories popped up along the river. Workers dumped all of their sewage into the river. Residents dumped all of their sewage into the river. It flowed out into the lake, the source of the city's drinking water. Diseases like typhoid and cholera flourished.
Finally, in 1900, Chicago city planners reversed the flow of the river, diverting it west into the Mississippi River. The waterborne diseases disappeared. Even so, it was still called "the stinking river" due to the garbage that continued to be dumped in it.
With the reversal of the river, a new problem arose. Chicago continued to produce sewage. Now the pollution floated downstream to cities like St. Louis, Missouri. When my parents stopped there en route to California on their honeymoon in 1960, they noticed many young disabled people. The cause was polio. The source of the disease was the sticky city's many private and public pools. The pools received their water from the Mississippi.
In the 1980's, Mayor Daley finally cracked down on the dumping of garbage in the Chicago River. Its waters started to turn green (from the sediment at the bottom) rather than brown. Lake Michigan turned a crystal blue. Wildlife started to return including over 60 types of fish. And the river that almost undid the city, became a blessing once again.