Peoria sewage warning after rain triggers CSO into Illinois River: what to do

The City of Peoria posted an archived sewage warning after rainfall caused a combined sewer overflow (CSO) into the Illinois River.

The notice says rainfall caused a CSO into the Illinois River within the last 48 hours from one or more overflow locations shown on the city map. While this warning is posted, the city instructs residents to:

• Avoid full-body contact with the Illinois River in the area downstream from Detweiller Marina.
• Don’t swallow river water while swimming, Jet Skiing, or water skiing in these areas, because people may get sick after a CSO event.

Where the warning applies (and why the map matters)

The city ties the advisory to specific overflow locations shown on its map, with guidance focused on the river reach downstream from Detweiller Marina for this event. If you’re planning river recreation after rain, the practical step is to check Peoria’s CSO warning/notification page for any newer notices and the mapped areas they cover.

Quick explainer: what a CSO is in Peoria

Peoria’s public works explanation of CSOs starts with the fact that the city’s older combined sewer system carries both sanitary wastewater (sewage) and stormwater (runoff). Under normal conditions, flows go to the wastewater plant for treatment.

But after heavy rain or snowmelt, stormwater can overwhelm the system, and untreated sewage can be released into the Illinois River. Peoria says CSOs happen between 20 and 30 times a year (on average), and that CSOs can cause elevated bacterial levels that exceed levels considered safe for contact.

How this warning connects to the Clean Water Act and the CSO Consent Decree

Peoria’s notice points residents to the broader cleanup effort behind it—projects to reduce CSOs during wet weather, as required under the Clean Water Act and the CSO Consent Decree.

In a federal announcement on Dec. 23, 2020, the U.S. EPA said the framework involves a proposed consent decree designed to resolve Clean Water Act violations tied to CSOs and permit exceedances. EPA estimated Peoria’s overall CSO controls would cost about $129 million and would be completed by Jan. 1, 2040, with interim milestones to track progress.

What to watch next

Because this specific post is labeled archived, don’t assume it’s the latest instruction for July 25. Before using the Illinois River downstream from Detweiller Marina after future storms, check the city’s CSO notifications/warning page for any updates.

When a CSO warning is posted, follow the city’s health guidance: avoid full-body contact and don’t swallow river water during swimming, Jet Skiing, or water skiing in the affected areas.

Sources

• City of Peoria CSO Sewage Warning (Archived) – Civic Alerts
• U.S. EPA: EPA/DOJ/Illinois reach agreement with Peoria & GPSD to reduce CSO pollution (Dec. 23, 2020)
• Peoria Standard – report on the sewage warning