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Illinois / Waters /

North Branch Chicago River

River in Illinois, past Chicago, Libertyville, Moraine, New Trier, Niles, Northfield, Shields and West Deerfield

Current status

Discharge possible: heavy rain, no report received

Radar shows that recent rain at a combined sewer system's outlets has reached the amount set for that system, and its operator has not reported a discharge. It reads "discharge likely" where the amount is the one at which that system has discharged before, or a rain trigger its state publishes, and "discharge possible" where only this site's default of 0.1 inch applies. This is an estimate, not a report. This status since . 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. Grey dots are closed outfalls. A yellow ring with a dashed edge means discharge likely or possible: heavy rain, no report received. Square boat markers mark boat launches listed by OpenBoatLaunch.

Get alerts from City of Chicago (Chicago CSO) · Bookmark this water page and check it before each trip · Report a missing notice or error

About this status

Discharge possible: heavy rain, no report received: heavy rain at a sewer operator's outlets reached this site's default amount, and no report received; shown for 48 hours after the rain (site rule). 3.9 in of rain fell in the 24 hours to Nov 6, 2026, 2:00 AM CST at Metro Water Reclamation District Of Greater Chicago (MWRDGC Terrence J O'Brien WTR Reclamation Plant)'s outfalls (NOAA radar estimate).

Source: NOAA National Weather Service, MRMS radar-only rainfall estimate, valid Nov 6, 2026, 2:00 AM CST, retrieved 2026-11-06 08:57 UTC; threshold: site default; rule: How it works, discharge likely or possible. · Updated

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.

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 the North Branch Chicago River 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 the North Branch Chicago River 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 the North Branch Chicago River 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 the North Branch Chicago River in Illinois0.0%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 the North Branch Chicago River in Illinois4Reported on the North Branch Chicago River in Illinois: 0 · Arriving from outfalls upstream, estimated: 0 · Other records (rain-likely and similar): 4last 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.

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.

Reported discharges per month

1 reported discharge, January 2022 to November 2026.

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

The U.S. Environmental Protection Agency's sewer overflow records are limited: they hold only what operators file with the agency.

Source: U.S. Environmental Protection Agency sewer overflow records. Records cover May 3, 2022 to November 6, 2026.

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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

The U.S. Environmental Protection Agency's sewer overflow records are limited: they hold only what operators file with the agency.

Source: U.S. Environmental Protection Agency sewer overflow records. Records cover May 3, 2022 to November 6, 2026.

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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: U.S. Environmental Protection Agency sewer overflow records. Records cover May 3, 2022 to November 6, 2026.

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Reported discharges per year, 2000 to 2026

1 reported discharge, 2000 to 2026.

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

The U.S. Environmental Protection Agency's sewer overflow records are limited: they hold only what operators file with the agency.

Source: U.S. Environmental Protection Agency sewer overflow records. Records cover May 3, 2022 to November 6, 2026.

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Reported volume per year

Gallons (axis: K thousand, M million), summed from the 1 report that gave a volume as a number.

  • Incomplete source coverage
Limited records

Source: U.S. Environmental Protection Agency sewer overflow records. Records cover May 3, 2022 to November 6, 2026.

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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: U.S. Environmental Protection Agency sewer overflow records. Records cover May 3, 2022 to November 6, 2026.

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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: U.S. Environmental Protection Agency sewer overflow records. Records cover May 3, 2022 to November 6, 2026.

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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: U.S. Environmental Protection Agency sewer overflow records. Records cover May 3, 2022 to November 6, 2026.

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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 North Branch Chicago River

Reports linked to North Branch Chicago River, newest first
WhenReportStatus
to 8:00 AM CSTVillage of Deerfield · SSO · 24,750 gallons report · notice · mapended

Sources: EPA ECHO Sewer Overflow and Bypass Event report (reported to regulators), retrieved 2026-11-06 08:38 UTC. A report's record id and times show when you hover or focus its "report" link.

Download these reports as CSV

All reports in Illinois by year: 2025 (1 here)

Wastewater outlets on this water

Outfall: a pipe or outlet where wastewater enters a water body.

Combined sewer outfalls

102 outfalls · 1 closed · discharge possible now at 101

Discharge possible: heavy rain, no report received at 101 outfalls now: radar rainfall has reached the operator's threshold and no discharge report has arrived (NOAA radar estimate).

Showing 12 of 102.

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

1 outfall

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: City of Chicago (Chicago CSO), Metro Water Reclamation District Of Greater Chicago (MWRDGC Terrence J O'Brien WTR Reclamation Plant), Village of Deerfield, Village of Morton Grove (Morton Grove CSOS), Village of Niles (Niles CSOS).

Boat launches

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

Nearby waters

Sources covering this water

1 record linked to this water. Updated .