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Illinois / Waters /

Lake Michigan

Lake in Illinois, near Benton, Chicago, Evanston, Moraine, New Trier, Shields, Waukegan and Zion

Current status

No current status shown

No current status is assigned to this water outline. Check the water page for reports and any estimated downstream stretches. Why this status, and its source

Map sources: water outlines and launches from OpenBoatLaunch and OpenStreetMap contributors (Open Database License); wastewater outlets from EPA and state records; downstream estimates by DirtyWaterWatch using U.S. Geological Survey maps and flow data. Base map: OpenFreeMap and OpenMapTiles.

Solid dots mark combined sewer outfalls. Ringed dots mark treatment plant outfalls. Square boat markers mark boat launches listed by OpenBoatLaunch. Dashed river stretches are estimates.

Get alerts from Metro Water Reclamation District Of Greater Chicago (MWRDGC Calumet WRP) · Bookmark this water page and check it before each trip · Report a missing notice or error

About this status

No current status shown: no report we track sets a status on this water now; how statuses work. No status does not mean the water is safe. Follow posted signs and local health advice.

Sources checked: a public source (last successful check 2026-11-06 08:38 UTC); a public source (last successful check 2026-11-06 08:39 UTC); MWRD Lake Michigan reversals table (1985 to present) (last successful check 2026-11-06 08:41 UTC). Status by DirtyWaterWatch, updated 2026-11-06 09:03 UTC. · Updated

Estimated downstream stretches on Lake Michigan

none with a current status

No downstream stretch has a current status here as of Nov 6, 2026, 3:03 AM CST. Check the reports below.

Estimated routes below wastewater outlets

5 routes below outlets
  • No current status shown Permit IL0028053, outlet Chicago River Controlling Works · 40 kilometres estimated · Estimate stops here
  • No current status shown Permit IL0028061, outlet OBrien Lock and Dam · 50.93 kilometres estimated · Estimate stops here
  • No current status shown Permit IL0028088, outlet Wilmette Gate · 40 kilometres estimated · Estimate stops here
  • No current status shown Permit IL0030244, outlet 002 · 40 kilometres estimated · Estimate stops here
  • No current status shown Permit IL0035092, outlet 020 · 40 kilometres estimated · Estimate stops here

Source: DirtyWaterWatch estimates using U.S. Geological Survey river maps and flow measurements. The estimate stops at tidal water, the first lake or the distance limit.

The last 90 days

Last 90 days, hour by hour. Red: discharge or advisory reported. Amber: caution. Hatched amber: end not confirmed. Plum: algal bloom advisory. Red or amber with a light line inside: beach advisory or caution. Dotted: monthly report (days with discharge, dates not given). Grey: no current status on the water outline. Purple hatching: a status resting on a source that could not be checked on schedule.

No discharge, advisory or caution periods are shown for this water in this time span. Check downstream stretches and source coverage.

Source: DirtyWaterWatch calculations using the reports named above and the published status rules. Updated 2026-11-06 09:03 UTC.

Reported discharges over time

  • Discharges affecting Lake Michigan in Illinois, last 12 months0December 2025 to November 2026Verified reports where available, else notices; revisions and duplicates counted once. Arriving discharges are estimated from modeled downstream reaches.
  • Days with a discharge affecting Lake Michigan in Illinois, last 12 months0December 2025 to November 2026A day counts once however many discharges were under way on it.
  • Hours with a discharge or advisory status on Lake Michigan in Illinois, last 12 months0December 2025 to November 2026Red hours by the map's rules: each discharge to its reported end plus the state's post-discharge period; overlapping hours count once.
  • 2023 season with a discharge or advisory status on Lake Michigan in Illinois1.6%May to October 2023; incomplete source coverageShare of May 1 to October 31 hours with red status by the map's rules, of the hours a source covered.
  • Records behind the last-90-days strip for Lake Michigan in Illinois0last 90 daysEvery distinct record the strip lists for its red, yellow and unresolved hours, notices and unresolved reports included; counted as the strip counts them.

This record covers Lake Michigan within Illinois; the same lake in another state is a separate record.

Combined sewer overflow (CSO): sewage mixed with rainwater spills from a shared sewer system. Sanitary sewer overflow (SSO): sewage spills from a sewer meant to carry sewage separately from rainwater. Treatment bypass: wastewater skips one or more treatment steps. Blended discharge: wastewater that skipped some treatment is mixed with treated wastewater. Outfall: a pipe or outlet where wastewater enters a water body.

Reported discharges per month

2 reported discharges, January 2022 to November 2026.

  • Combined sewer overflow
  • Sanitary sewer overflow
  • Treatment bypass, blended or other
  • Incomplete source coverage
Limited records

Source: il-mwrd-lake-michigan-reversals. Records cover January 1, 2022 to July 3, 2023.

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Hours with a discharge or advisory status per month

Hours when this water had a discharge or advisory status under DirtyWaterWatch rules.

  • Discharge or advisory reported
  • Incomplete source coverage
Limited records

Source: il-mwrd-lake-michigan-reversals. Records cover March 4, 1985 to July 3, 2023.

Show table

Days with a reported discharge per month

A day counts when any counted discharge was under way on it, from its start to its reported end in Eastern Time; a report with no end counts its start day.

  • Incomplete source coverage
Limited records

Source: il-mwrd-lake-michigan-reversals. Records cover January 1, 2022 to July 3, 2023.

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Reported discharges per year, 2000 to 2026

36 reported discharges, 2000 to 2026.

  • Combined sewer overflow
  • Sanitary sewer overflow
  • Treatment bypass, blended or other
  • Incomplete source coverage
Limited records

Source: il-mwrd-lake-michigan-reversals. Records cover March 4, 1985 to July 3, 2023.

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Reported volume per year

Gallons (axis: K thousand, M million), summed from the 33 reports that gave a volume as a number (3 did not).

  • Incomplete source coverage
Limited records

3 of 36 discharge reports gave no volume as a number; only numbers are summed. 3 reports give more than 5 billion gallons for a single discharge, which looks like an entry error; they are not summed.

Source: il-mwrd-lake-michigan-reversals. Records cover March 4, 1985 to July 3, 2023.

Show table

Hours with a discharge or advisory status per year

Hours with a discharge or advisory status each year under DirtyWaterWatch rules; 2026 to date.

  • Discharge or advisory reported
  • Incomplete source coverage
Limited records

Source: il-mwrd-lake-michigan-reversals. Records cover March 4, 1985 to July 3, 2023.

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Share of the May to October season with a discharge or advisory status

Share of the hours from May 1 to October 31 with a discharge or advisory status under DirtyWaterWatch rules.

  • Discharge or advisory reported
  • Season with incomplete source coverage

Seasons with incomplete source coverage: 2023. The share is of the hours a source covered.

Source: il-mwrd-lake-michigan-reversals. Records cover March 4, 1985 to July 3, 2023.

Show table

Reported discharges by calendar month, all years

Every counted discharge report, by the calendar month it began.

Months are summed over every year a tracked source covers; the table gives the number of years behind each month.

Source: il-mwrd-lake-michigan-reversals. Records cover March 4, 1985 to July 3, 2023.

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Reported discharges by wastewater outlet

Wastewater outlets with the most tracked discharge records: 3 of 3, all years. Counts depend on reporting coverage and do not measure legal compliance or harm.

Source: il-mwrd-lake-michigan-reversals. Records cover March 4, 1985 to July 3, 2023.

Show table
How these charts are counted

We count each discharge once. Where a source publishes notices and confirmed reports, we use confirmed reports for an operator's month when available; otherwise we use notices. We combine revisions and exclude duplicate state reports copied by the U.S. Environmental Protection Agency (EPA). Monthly and yearly totals appear separately. Status hours follow this site's rules. Shaded gaps mean missing coverage, not zero discharges.

  • U.S. Environmental Protection Agency sewer overflow records: records from May 3, 2022 to the latest update (limited records)
  • il-mwrd-lake-michigan-reversals: records from March 4, 1985 to July 3, 2023

Reports linked to Lake Michigan

Reports linked to Lake Michigan, newest first
WhenReportStatus
to Jul 3 ’23Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 230.8 million gallons report · notice · mapended
to Jul 3 ’23Metro Water Reclamation District Of Greater Chicago · Chicago River Controlling Works Chicago River Controlling Works · CSO · 911.8 million gallons report · notice · mapended
to May 18 ’20Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 766.7 million gallons report · notice · mapended
to May 18 ’20Metro Water Reclamation District Of Greater Chicago · Chicago River Controlling Works Chicago River Controlling Works · CSO · 1,731.6 million gallons report · notice · mapended
to May 15 ’20Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 50.1 million gallons report · notice · mapended
to Oct 3 ’19Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 54.5 million gallons report · notice · mapended
to Oct 15 ’17Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 289.8 million gallons report · notice · mapended
to Oct 15 ’17Metro Water Reclamation District Of Greater Chicago · Chicago River Controlling Works Chicago River Controlling Works · CSO · 2,456.4 million gallons report · notice · mapended
to Apr 30 ’17Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 19.3 million gallons report · notice · mapended
to Jul 24 ’16Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 34 million gallons report · notice · mapended
to Jun 16 ’15Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 167.2 million gallons report · notice · mapended
to Jun 16 ’15Metro Water Reclamation District Of Greater Chicago · Chicago River Controlling Works Chicago River Controlling Works · CSO · 997.5 million gallons report · notice · mapended
to Jul 1 ’14Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 163 million gallons report · notice · mapended
to Jul 1 ’14Metro Water Reclamation District Of Greater Chicago · Chicago River Controlling Works Chicago River Controlling Works · CSO · 362 million gallons report · notice · mapended
to Apr 19 ’13Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 1,429.2 million gallons report · notice · mapended
to Apr 19 ’13Metro Water Reclamation District Of Greater Chicago · OBrien Lock and Dam O'Brien Lock and Dam (Calumet River) · CSO · 3,185.6 million gallons report · notice · mapended
to Apr 19 ’13Metro Water Reclamation District Of Greater Chicago · Chicago River Controlling Works Chicago River Controlling Works · CSO · 6,104.7 million gallons report · notice · mapended
to Jul 23 ’11Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 504.3 million gallons report · notice · mapended
to Jul 23 ’11Metro Water Reclamation District Of Greater Chicago · Chicago River Controlling Works Chicago River Controlling Works · CSO · 1,716.2 million gallons report · notice · mapended
to May 29 ’11Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 107 million gallons report · notice · mapended
to Jul 24 ’10Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 750.3 million gallons report · notice · mapended
to Jul 24 ’10Metro Water Reclamation District Of Greater Chicago · Chicago River Controlling Works Chicago River Controlling Works · CSO · 5,784.6 million gallons report · notice · mapended
to Jun 19 ’09Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 191.6 million gallons report · notice · mapended
to Mar 8 ’09Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 143.1 million gallons report · notice · mapended
to Feb 27 ’09Metro Water Reclamation District Of Greater Chicago · Wilmette Gate Wilmette gate (North Shore Channel) · CSO · 78.9 million gallons report · notice · mapended

Sources: MWRD Lake Michigan reversals table (1985 to present), retrieved 2026-11-06 08:41 UTC. A report's record id and times show when you hover or focus its "report" link.

Download these reports as CSV

Showing the latest 25 records of 57 records.See them all with filters.

All reports in Illinois by year: 2023 (2 here) · 2020 (3 here) · 2019 (1 here) · 2017 (3 here) · 2016 (1 here) · 2015 (2 here) · 2014 (2 here) · 2013 (3 here) · 2011 (3 here) · 2010 (2 here) · 2009 (3 here) · 2008 (4 here) · 2007 (1 here) · 2002 (2 here) · 2001 (4 here) · 1999 (1 here) · 1997 (5 here) · 1996 (2 here) · 1990 (6 here) · 1989 (1 here) · 1987 (3 here) · 1986 (1 here) · 1985 (2 here)

Wastewater outlets on this water

Combined sewer outfalls

3 outfalls

Source: U.S. Environmental Protection Agency (EPA) national combined sewer outfall inventory (ECHO) and state outfall layers. Open or closed as EPA's inventory lists it. DirtyWaterWatch links outlets to waters using permit numbers, locations and names.

Treatment plant outfalls

2 outfalls

Source: U.S. Environmental Protection Agency (EPA) permit records (ICIS-NPDES permitted features): where a treatment plant’s permitted discharge leaves. No national source says whether a plant outfall is open or closed.

Sewer operators listed for this water: Metro Water Reclamation District Of Greater Chicago (MWRDGC Calumet WRP), Metro Water Reclamation District Of Greater Chicago (MWRDGC Stickney WRP), Metro Water Reclamation District Of Greater Chicago (MWRDGC Terrence J O'Brien WTR Reclamation Plant), North Shore Water Reclamation District.

Boat launches

Source: OpenBoatLaunch launch records (public agency data and OpenStreetMap, Open Database License).

Nearby waters

Sources covering this water

57 records linked to this water. Updated .