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NPDES Permit
Types of Sewer Systems
The Village of La Grange maintains and operates three different types of sewer systems:
  • Combined sewer systems
  • Sanitary sewer
  • Storm sewer

The combined sewer system is designed to convey both rainfall runoff and domestic and industrial wastewater in a single pipe to wastewater treatment plants operated by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC).

The sewer systems are regulated by the U.S. Environmental Protection Agency (U.S. EPA) through the Illinois Environmental Protection Agency (IEPA) as well as the MWRDGC, which treats the sanitary sewage from the Village.

National Pollutant Discharge Elimination System (NPDES)
The Village is permitted to discharge wet weather sewer flows conveyed by its combined sewer system, which is not collected by the Deep Tunnel system.  These sewer flows are discharged into regional surface waterways under a special National Pollutant Discharge Elimination System (NPDES) Permit issued by the IEPA.

The surface waterway receiving the Village’s combined sewer wet weather overflow is the Salt Creek tributary to the Des Plaines River.

Additional Information
Additional information regarding the Village's NPDES permit can be found in the following links: