The Economic Times

In 1972, Chicago began digging 110 miles of sewer tunnel up to 300 feet down; 50 years on, the Deep Tunnel has captured more than a trillion gallons of combined sewage

Chicago's Deep Tunnel project has been a vital safeguard for Lake Michigan over the past fifty years. Initiated in 1972, this impressive 110-mile sewer system was designed to tackle combined sewer overflows and urban flooding. By 2006, the tunnel segment had significantly curtailed sewer-related pollution throughout the city. However, reservoir construction persists, with anticipated completion by 2029, mirroring similar infrastructure challenges faced by many U.S. cities.