Amidst a deluge of heavy rainfall in Chicago, an extraordinary decision was made to reverse the flow of the Chicago River, an action rarely taken. The Metropolitan Water Reclamation District of Greater Chicago announced that the river's locks near Wilmette were opened around 2:30 p.m. on Sunday and closed just before 10 p.m. Additionally, locks near downtown Chicago were opened at approximately 4 p.m. on Sunday and remained open until 2:30 a.m. on Monday.
The exact volume of water released into Lake Michigan remains unknown at this time. The reversal of the river's flow traces back to the early 1900s when it was initially implemented to address pollution concerns in Lake Michigan. Authorities only resort to opening the locks during critical moments when water levels pose a threat to homes and businesses.
Although infrequent, the river's flow was reversed once in 2019 and twice in 2020, but no such reversals occurred in the past two years. Authorities generally avoid this measure because it leads to the discharge of untreated wastewater into Lake Michigan, which helps alleviate pressure on the city and suburban sewer systems.
Following the reversal on Sunday, several Chicago beaches were temporarily closed due to water quality concerns. However, with the exception of Marian Mahony Park, all beaches have since reopened. Swimming remains prohibited in suburban Evanston due to elevated E. coli levels in the water.
The decision to reverse the river's flow also prevented damage along the city's Riverwalk, which had been closed from Lake Street to State Street after the river overflowed its banks. City officials report that cleanup efforts are ongoing, with residual debris and standing water being the only remnants of the flooding. Fortunately, no significant damage has been reported as water-tolerant plants and fixtures were designed to withstand short-term inundation.