Raw Sewage Released Into Lake To Lower River Levels

WILMETTE, IL — During last weekend's storms, millions of gallons of sewage and storm runoff were pumped into Lake Michigan to relieve the strain on the area's sewers and stormwater drainage system. To reduce water levels, officials from the Metropolitan Water Reclamation District opened the gates that separate Lake Michigan from the Chicago River system for more than five hours.

With rising water levels on the river having reached three feet above the lake, water officials opened the Wilmette locks on the North Shore Channel, reversing the flow and sending untreated water and raw sewage into the source of the Chicago area's drinking water.

The gates remained open from from 11:05 p.m. Saturday until 4:30 a.m. Sunday, according to a spokesperson for the water district.

On Monday morning, the National Weather Service issued a flood warning through Wednesday for areas near the Des Plaines River, which had already risen above its 15-foot flood stage. The river was projected to reach a peak of 15.7 early Tuesday. Campground Road, running parallel to the river, was closed with standing water between Campground and Algonquin roads and Big Bend Drive, the Journal and Topics reported.

It will be several days before estimates are available for exactly how many raw sewage overflow and how many gallons of untreated water was pumped into the lake during the storm, David St. Pierre, the executive director of the MWRD, told the Sun-Times.

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The locks are opened under storm conditions only if the river reaches a predefined level. They are closed as soon as the water recedes below the threshold, according to the Village of Wilmette.

Sending sewage into the lake is not an ideal solution. St. Pierre told the paper the Wilmette locks normally only need to be opened about once a year, and a new reservoir in southwest suburban McCook scheduled for completion at the end of the year — constructed as part of the MWRD's Tunnel and Reservoir Plan — should make it even less likely in the future.

Top photo | North Shore Channel | Street View