CHICAGO (CBS) — The heavy rainfall from Monday night’s storms prompted officials to open the Chicago and Wilmette locks to prevent raw sewage from overflowing out of the sewer system, and instead dump a mix of storm runoff and sewage into Lake Michigan.
More than two inches of rain fell in Chicago during two rounds of severe thunderstorms, overwhelming the Deep Tunnel system designed to store storm runoff and prevent the need to open the locks that divide Lake Michigan from the Chicago River. Up three or four inches of rain fell in some suburbs.
The Metropolitan Water Reclamation District of Greater Chicago said it opened the Chicago River locks downtown shortly before 1 a.m, and closed them again at 7:10 a.m. The gates at Wilmette were opened at 11:23 p.m. Monday, and closed at 5:50 a.m. Tuesday.