Between one to more than four inches of rain have fallen throughout the Chicago metropolitan area over the past two days. The levels and intensity of rainfall have varied across the region with more hitting the central and northern suburbs of the county the hardest this morning.

To minimize overbank flooding and to mitigate the impact of the storm event, we have reversed the flow of the Chicago Area Waterway System to Lake Michigan at the Wilmette Pumping Station. There are several factors we consider when determining to release floodwater to the lake, including the rate the river water level is rising at each lakefront control location, whether the rainfall intensity is continuing or beginning to decrease and the storm conditions on the radar.

The Tunnel and Reservoir Plan is comprised of three systems, and all are operating as designed to hold excess water.

The U.S. Army Corps of Engineers provides data on the lake level.

Storm update July 2 2023.pdf