NPDES Discharge Permit

Sewer System


Portions of the Western Springs sewer system serve as conveyances for both stormwater and domestic sewage. In the event a rainfall exceeds the capacity of the combined sewers, the excess is discharged through outfalls along Flagg Creek and Salt Creek.

The combined sewer system in Western Springs is limited to the area north of 47th Street. Areas south of 47th Street are served by separate storm and sanitary sewers. Wastewater from combined and separate sanitary sewers is collected and treated by the Water Reclamation District of Greater Chicago (MWRD-GC).
In 2012, the Village completed and submitted to the IEPA the 2012 CSO Long Term Control Plan with Baxter & Woodman, Inc. This long term control plan outlines the existing conditions of the CSO's within the Village as well as possible scenarios for alternatives and possible removal of the CSO's. The plan was updated in 2015. 


Flag Creek Watershed


The combined sewers in the Flagg Creek watershed meet at a trunk sewer that originates at the intersection of 47th Street and Fair Elms Avenue. This 18-inch trunk sewer transports the combined sewage south along Fair Elms Avenue to an MWRD-GC interceptor near 55th Street.

If wet-weather flows exceed the capacity of the 18-inch trunk sewer, the excess flow is discharged through Outfall 3 (Fair Elms and 49th Street) into Flagg Creek. If flows exceed the interceptor at 55th street, the excess flow will be discharged into Flagg Creek through Outfall 4.

Discharge Permit


The Village of Western Springs holds a discharge permit from the National Pollutant Discharge Elimination System (NPDES), and one of the policies of that permit is to inform the public about a combined sewer overflow (CSO) event. When such an event happens, the public will be informed through the village's website.  

Combined Sewer Overflow Updates


  • August 3rd, 2017 the 47th Street CSO discharged from 9:03 PM to 10:04 PM
  • July 20th, 2017 the 47th Street CSO discharged from 8:19 AM to 8:47 AM
  • June 12th, 2017 the 47th Street CSO discharged from 11:00 PM to 11:10 PM
  • May 10th, 2017 the 47th Street CSO discharged from 8:14 PM to 10:47 PM
  • February 28th, 2017 the 47th Street CSO discharged from 10:22 PM to March 1st, 2017 at 12:35 AM