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Metropolitan Water Reclamation District of Greater Chicago Settlement

(Washington, DC - December 14, 2011) The Department of Justice and the U.S. Environmental Protection Agency (EPA) today announced a Clean Water Act (CWA) settlement with the Metropolitan Water Reclamation District of Greater Chicago (MWRD) to resolve claims that untreated sewer discharges were released into Chicago area waterways  during flood and wet weather events. The settlement will safeguard water quality and protect human health by capturing wet weather flows entering the combined sewer system, which services the city of Chicago and 51 communities.

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Overview of Facility

The Metropolitan Water Reclamation District of Greater Chicago (MWRD), based in Chicago,  provides sewage treatment and wastewater services to Chicago and surrounding areas.

Three of MWRD’s seven sewage treatment plants (the North Side, Calumet and Stickney plants) and associated collection systems, serve the City of Chicago and 51 communities having combined sewer systems that also have combined sewer overflows (CSOs).

MWRD owns 36 CSO outfalls located on Chicago area river ways. The 51 satellite communities own 334 CSO outfalls also located on Chicago area river ways. 

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The Complaint alleges violations of the Clean Water Act (CWA) Sections 301 and 402 in the form of discharges of untreated sewage from MWRD's sewage collection system, including CSOs to Chicago area waterways.

Other violations alleged in the Complaint include:

  • Failure to provide the equivalent of primary treatment plus disinfection for up to ten times the average dry weather flow
  • Failure to prevent floatables and solids in CSOs from entering Chicago area waterways, as required under MWRD's National Pollution Discharge Elimination System (NPDES) permits
  • Causing or contributing to exceedances of water quality standards for dissolved oxygen 

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Injunctive Relief

MWRD will complete implementation of CSO remedial measures to eliminate a substantial percentage of CSOs by December 31, 2029, that, upon completion, are estimated at as cost of more than $3 billion. These measures include: 

  • An enforceable schedule for completion of CSO remedial measures known as the “tunnel and reservoir plan.” This plan includes the construction of 109 miles of tunnels that have a storage capacity of approximately 2.3 billion gallons, and the completion of three reservoirs. The tunnel and reservoirs will have a combined capacity of approximately 17 billion gallons of sewage and flood water
  • A robust and enforceable plan to control debris ("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
  • Post-construction monitoring following completion of the tunnel and reservoir plan to ensure compliance with permit requirements and water quality standards

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Health and Environmental Effects

CSO overflows may adversely affect lakes and waterways, and include viruses, bacteria, and other pathogens, oxygen-demanding pollutants, suspended solids, nutrients, toxics, and floatable matter that can harm water resources. Health and environmental impacts from CSO overflows include the following:

  • Total Suspended Solids – TSS indicates the measure of suspended solids in wastewater, effluent or water bodies. High levels of TSS in a water body can diminish the amount of light that penetrates the water column and reduce photosynthesis and the production of oxygen. 
  • Biological Oxygen Demand – BOD is an indirect measure of the biologically degradable material present in organic wastes. High BOD means there is an abundance of biologically degradable material that will consume oxygen from the water during the degradation process. It may take away oxygen that is needed for aquatic organisms to survive. 
  • Chemical Oxygen Demand – COD is a measure based on the chemical decomposition of organic and inorganic contaminants, dissolved or suspended in water. As with BOD, high levels of COD indicate high levels of pollutants are present in the wastewater that will consume oxygen from the water, and may take away oxygen that is needed for aquatic organisms to survive. 

More information about all three of the above measures of health and environmental impacts can be found at in the Environmental Protection Agency (2004) EPA Report to Congress (PDF) 30pp, 3M, About PDF).

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Green Infrastructure

The Consent Decree also includes a Green Infrastructure Program that is estimated to cost anywhere between $25 and $50 million. The overall goal of the Program is to increase acceptance of and investment in Green Infrastructure measures within MWRD’s service area and to reduce CSO discharges, localized flooding and stormwater impacts. Where feasible, MWRD will prioritize projects where they: 

  • Help reduce flooding and basement backups
  • Can be readily accommodated as permanent stormwater control measures
  • Can undertake projects that will convert vacant land parcels into "stormwater parks," that will store and reuse rainfall and stormwater runoff and also be amenity for local residents
  • Can improve socio-economic conditions in the MWRD service area where the need is greatest (specifically by improving conditions in areas impacted by environmental justice concerns)

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Environmental Justice

CSOs from MWRD and satellite communities’ outfalls discharge into numerous Chicago area waterways. The MWRD combined sewer service area is approximately 350 square miles and the entire service area includes 76 miles of river way, more than half of which includes minority populations (55 percent) and residents living in poverty (15 percent).
Injunctive relief under the settlement will have the following effects on those populations. 


  • CSO remedial control measures known as the Tunnel and Reservoir Plan (TARP) – Chicago is the largest satellite community in the MWRD service area with a 67 percent minority population and 20 percent living below the poverty level.
  • All of the waterways affected by CSOs in this matter at some point flow adjacent to an environmental justice area of concern identified by EPA. When the TARP systems are completed, the settlement will have reduced the potential exposure to combined sewage to low income and minority populations in the service area. It will also mean less combined sewage flowing directly into the river resulting in benefits to communities downstream from the CSO discharges as well. 
  • Green Infrastructure (GI).  MWRD's GI plan, must prioritize projects by considering locations where GI control measures may be able to help reduce basement backups and flooding, and at the same time improve socio-economic conditions in neighborhoods with greater preexisting needs and vulnerabilities. The Decree also requires MWRD, in its planning and implementation of GI projects, to include a public participation process that will include measures to engage people living in such neighborhoods. The public participation process also will permit MWRD to employ socio-economic data to identify neighborhoods of concern.

Civil Penalty

MWRD will pay a total civil penalty of $675,000 as follows:

  • $350,000 to the United States
  • $325,000 to the state of Illinois 

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State Partners

The State of Illinois is a co-plaintiff in this case.

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Comment Period

The proposed settlement, lodged in the U.S. District Court for the Northern District of Illinois, is subject to a 30-day public comment period and final court approval. Information on submitting comment is available at the Department of Justice website.

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For more information, contact:

Sushila Nanda
Senior Attorney Advisor
Ariel Rios Building (Mail Code 2243A)
1200 Pennsylvania Avenue, NW
Washington, DC 20460
(202) 564-4088
Sushila Nanda (

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