Atbeginning of the 20th centurythe city of Chicago (USA) had to face a great environmental challenge caused by its urban and industrial growth: the river which crosses the city had transported up to theAug Michiganthe main water supply of the entire area, including Chicago, such a quantity of pollutants and other toxic substances to contaminate the waters of the basin. To avoid further exaggerating the enormous environmental and health problems resulting from this, in 1900 the engineer Sylvester Chesbrough a seemingly crazy idea came up: reverse the flow of the river Chicago with a colossal engineering feat.