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U.S. V. Metropolitan Water Reclamation District Of Greater Chicago (N.D. Ill.)

Whatcom Creek. Photo courtesy of R. Wolotira, NOAA.

EES | Cases by Practice Area


 The Metropolitan Water Reclamation District of Greater Chicago (MWRD) is responsible for the operation and management of wastewater and stormwater collection and treatment in a combined sewer system in the Chicago area. Combined sewer systems are designed to collect stormwater runoff, domestic sewage and industrial wastewater in the same pipe and transport it to a sewage treatment plant, where it is treated before discharge to a water body. During periods of heavy rainfall or snowmelt, however, the wastewater volume in a combined sewer system can exceed the capacity of the sewer system or treatment plant. For this reason, combined sewer systems are designed to overflow occasionally, through combined sewer overflows or CSOs, and discharge excess flows directly to nearby water bodies.

The Environmental Enforcement Section, along with the State of Illinois, filed a Complaint alleging violations of the National Pollutant Discharge Elimination System (NPDES) permits issued to MWRD relating to three of its treatment plants, which receive flows from combined sewer collection systems in a portion of the MWRD’s service area that includes Chicago and 51 suburbs. The Complaint alleges that discharges of untreated sewage mixed with stormwater through CSOs have violated provisions of NPDES permits that prohibit the discharge of pollutants into waters of the United States that cause or contribute to violations of applicable water quality standards for dissolved oxygen, solids, and floatables.

Outcome:  Court Approved Settlement

The U.S. District Court for the Northern District of Illinois approved a consent decree (a settlement) resolving the claims alleged in the Complaint that requires the following:

  • MWRD must complete implementation of CSO remedial measures known as the “tunnel and reservoir plan” (TARP) on an enforceable schedule by completing construction of TARP’s remaining two massive reservoirs, at which point the system will have a combined design storage capacity of approximately 17 billion gallons. By the end of 2017, MWRD will have added 8.3 billion gallons of storage capacity to TARP, for a total storage capacity of approximately 11 billion gallons, more than quadrupling TARP’s current capacity of 2.6 billion gallons.

See below for schedule for completion of remaining aspects of TARP and associated additional storage capacity:

TARP Storage Volume Graph

The settlement also requires MWRD to:

  • Perform a wide ranging “green infrastructure” program consisting of measures such as permeable pavement and rain gardens to help reduce CSO discharges, localized flooding and basement backups, which includes mechanisms for public participation in developing green infrastructure projects.

  • Implement a comprehensive plan to control debris known as “floatables” in overflows to area waterways. In addition, two new skimmer boats will be purchased and dispatched to Chicago area waterways within 24 hours of the commencement of CSO events to collect floatable debris on a year round basis, weather and safety permitting.

  • Perform extensive post-construction monitoring following completion of TARP to confirm compliance with permit requirements and water quality standards.

  • Payment of civil penalty of $675,000 ($350,000 to the United States and $325,000 to the State of Illinois).

  • Intervenor citizen groups have appealed the case to the Seventh Circuit Court of Appeals in Chicago.

Additional Images:

Tunnel Reservoir PlanTunnel Reservoir Status



Updated May 14, 2015

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