Reversing the flow of a river

When these gates on the Chicago River were opened ceremoniously in 1900, the course of the river reversed direction, in the culmination of an eight year engineering project. The river was reversed to move the sewage it contained, dumped into the river by the booming city of Chicago, into a river system that leads away from the city and, eventually, to the Mississippi River and the Gulf of Mexico, instead of to Lake Michigan, as it did naturally. One of several rivers that have been reversed in the USA, this project was among the first and the largest. A total of 56 miles of canals were dug by the City in the early part of the 1900's to keep the waste out of the lake, in a network that is said to have involved more earth moving than digging the Panama Canal.