Wilmette and Kenilworth homeowners on combined sewer lines west of Ridge Road face another basement-backup risk this week, with heavy rain forecast to arrive Friday afternoon, Aug. 7, while the regional sewer system is still draining billions of gallons from storms earlier this summer.
The Metropolitan Water Reclamation District of Greater Chicago issued its second Overflow Action Alert in less than two weeks on Monday, Aug. 3, urging all Chicago-area residents to delay showers, baths, laundry, and dishwasher use before and during the storm. The MWRD alert warns of localized flooding through Friday night, with scattered rain continuing Saturday, Aug. 8, before conditions dry out Sunday, Aug. 9.
The timing matters for the North Shore. MWRD's Tunnel and Reservoir Plan, the massive underground system that catches overflow from North Shore communities, was storing approximately 4.7 billion gallons of water as of July 28, the day after the July 27 storm that hammered the area. The McCook Reservoir sat at 85% capacity by July 29. That reservoir had already reached full capacity six times in 2026 alone, compared to five times total between 2021 and 2025.
"We encourage everyone to conserve water when possible to create more capacity in our systems," MWRD President Kari K. Steele said in the announcement accompanying the alert.
What Wilmette homeowners should know
The flood-risk zone runs through Wilmette's west side, where homes built from the late 1800s through the 1940s share combined sewer pipes that carry both stormwater and sanitary flow. Wilmette's $61.5 million Neighborhood Storage Project, completed in 2023, stores overflow in underground vaults at Hibbard Park, Thornwood Park, and Community Playfields. The system holds up to 14 million gallons, roughly 21 Olympic swimming pools.
During the July 27 storm, those vaults captured 3.5 million gallons while the West Park Sanitary Storage & Pumping Station handled an additional 210,000 gallons. Village Manager Michael Braiman told the Village Board on July 28 that the storm dropped 3 to 4.05 inches of rain in a few hours. He called the system's performance "a great success in the ability to keep water out of residents' basements and prevent open-land flooding," as we reported July 29.
That system now faces a second major test within two weeks.
What to do now
The MWRD advises residents to take these steps before Friday afternoon:
- Delay showers and baths
- Flush toilets less frequently
- Postpone laundry and dishwasher loads
- Sign up for MWRD Overflow Action Day text alerts at mwrd.org
Glencoe: Green Bay Road project in progress
Separately, the MWRD has an active intergovernmental agreement with Glencoe for the South Green Bay Road Stormwater Improvement Project, which will upsize storm sewers and add detention west of Green Bay Road. The estimated cost is $3.4 million, with MWRD contributing $1 million.
Deadline reminder
North Shore residents who suffered damage in the July 27 storm have until Wednesday, Aug. 5, to complete Cook County's online damage survey under the disaster proclamation issued July 30 by Board President Toni Preckwinkle.
