The river whose waters were reversed by man: the Chicago River

If man sets his mind to it, he can accomplish great feats that mark his advancement as a civilization, and I believe this is a clear example, due to its sheer scale and its continued improvement over time.

In the 19th century, Chicago authorities decided to change the course of the Chicago River that flowed into Lake Michigan, for health reasons to avoid epidemics due to contamination of the source of drinking water for the city of Chicago, Lake Michigan.

In 1850, part of the flow began to be diverted to the Illinois and Michigan Canal to mitigate sanitary problems, and in 1990, Chicago sanitary officials decided to install floodgates at the mouth to prevent the water from flowing into Lake Michigan, and to completely reverse the flow to the new Chicago Sanitary and Ship Canal, which poured water into the Mississippi River basin, through the Des Plaines River and finally emptying into the Gulf of Mexico... what a change in the course of the water.

The following video from https://www.youtube.com/@wttw tells the story in detail:

Throughout the 20th century, the Chicago River's water quality has improved, but it was not until the last decade of the 20th century that the riverbed was clean and free of trash.

And in the cinema we have many movies available where you can see the Chicago River in all its current splendor, like in the movie "Bridesmaids." Here's the trailer: