The River That Was Reversed

The Chicago River is one of the few rivers in the world to have been permanently reversed. In 1900, city engineers completed a massive infrastructure project that redirected the river's flow away from Lake Michigan, the city's source of drinking water, after decades of raw sewage flowing into the lake had caused repeated cholera and typhoid outbreaks. The reversal required moving more earth than was excavated for the entire Panama Canal. Today the river flows inland toward the Mississippi River drainage, a feat of engineering that has no real precedent in the modern world.

Source: Wikipedia