<P> The River is also noteworthy for its natural and man - made history . In 1887 , the Illinois General Assembly , partly in response to concerns arising out of an extreme weather event in 1885 that threatened the city 's water supply , decided to reverse the flow of the Chicago River through civil engineering by taking water from Lake Michigan and discharging it into the Mississippi River watershed . In 1889 , the Illinois General Assembly created the Chicago Sanitary District ( now The Metropolitan Water Reclamation District ) to replace the Illinois and Michigan Canal , which had become inadequate to carry the city 's increasing sewage and commercial navigation needs , with the Chicago Sanitary and Ship Canal , a much larger waterway . The District completed this man - made hydrologic connection between the Great Lakes and Mississippi watershed in 1900 by reversing the flow of the Main Stem and South Branch of the river using a series of canal locks , and increasing the river 's flow from Lake Michigan , causing it to empty into the new Canal . In 1999 , this system was named a ' Civil Engineering Monument of the Millennium ' by the American Society of Civil Engineers ( ASCE ) . </P>
<P> The River is also noteworthy for its natural and man - made history . In 1887 , the Illinois General Assembly , partly in response to concerns arising out of an extreme weather event in 1885 that threatened the city 's water supply , decided to reverse the flow of the Chicago River through civil engineering by taking water from Lake Michigan and discharging it into the Mississippi River watershed . In 1889 , the Illinois General Assembly created the Chicago Sanitary District ( now The Metropolitan Water Reclamation District ) to replace the Illinois and Michigan Canal , which had become inadequate to carry the city 's increasing sewage and commercial navigation needs , with the Chicago Sanitary and Ship Canal , a much larger waterway . The District completed this man - made hydrologic connection between the Great Lakes and Mississippi watershed in 1900 by reversing the flow of the Main Stem and South Branch of the river using a series of canal locks , and increasing the river 's flow from Lake Michigan , causing it to empty into the new Canal . In 1999 , this system was named a ' Civil Engineering Monument of the Millennium ' by the American Society of Civil Engineers ( ASCE ) . </P>
when was the flow of the chicago river reversed
when was the flow of the chicago river reversed
1887 1900
1887 1900