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City of Memphis - Tennessee Sanitary Sewer Overflow Settlement

(Washington, DC - April 16, 2012) The U.S. Environmental Protection Agency, the U.S. Department of Justice, the Tennessee Department of Environment and Conservation and the Office of the Tennessee Attorney General announced a comprehensive Clean Water Act (CWA) settlement with the City of Memphis, Tenn. Memphis has agreed to make improvements to its sewer systems to eliminate unauthorized overflows of untreated raw sewage. Memphis estimates such work will cost approximately $250 million. 

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Overview of Municipality

The City of Memphis, Tennessee (Memphis) owns and operates the collection and transmission system, as well as two wastewater treatment plants (WWTP), of the separate sanitary sewer system.  The two wastewater treatment plants are the M.C. Stiles WWTP and the T.E. Maxson WWTP. Memphis’ two WWTPs have a designed treatment capacity of 225 million gallons per day and processes on average, 143 million gallons per day. Memphis’ sewage collection and transmission system includes approximately 2,350 miles of gravity lines, 50 miles of pressurized force mains, 85,000 manholes and 95 pump stations.    

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The Complaint alleges the following Clean Water Act violations:

  • Unpermitted Discharges from Sanitary Sewer System.  The United States alleges that on numerous occasions since July 2003, pollutants were discharged to the waters of the United States, or the state, from sanitary sewer overflows (SSOs). These SSOs are from point sources within Memphis’ collection and transmission systems which were not identified in the National Pollutant Discharge Elimination System (NPDES) permit as authorized outfalls.  None of these discharges were permitted or otherwise authorized by the Act. 
  • Failure to Comply with Standard Permit Conditions: Proper Management, Operation and Maintenance.  The United States alleges that Memphis failed to properly operate and maintain permitted facilities, the collection and transmission systems and the treatment system.  The failure to properly manage, operate and maintain resulted in many of the SSOs.
  • Failure to Comply with Foam Effluent Permit Condition.  Memphis failed to comply with the effluent permit condition, which provides, “There shall be no distinctly visible floating scum, oil, or other matter contained in the wastewater discharge.”  Both EPA and a citizens group documented photographs showing visible foam discharges from the M.C. Stiles wastewater treatment plant to the Mississippi River.

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Injunctive Relief

Memphis estimates it will spend approximately $250 million to complete the requirements under the Consent Decree and other improvements. 

The injunctive relief outlined in the Consent Decree requires Memphis to develop and implement Management, Operations and Maintenance (MOM) programs and assess/rehabilitate the sewer system.  Details of the injunctive relief are summarized below. 

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Sewer Assessment and Rehabilitation Program

Under the Consent Decree, Memphis will continue to implement their sewer assessment and rehabilitation programs while revising and adding to their current programs.  The assessment and the rehabilitation of the sanitary sewer system, as well as the ongoing MOM programs, will take place under two main requirements under the Consent Decree:

  • Ongoing MOM Programs
  • Priority Rehabilitation Projects   

Memphis will improve and continue to develop programs to ensure effective management, operations and maintenance (MOM) of their sanitary sewer system.  Memphis will continue to develop, improve and implement the following programs:

  • Sewer Overflow Response Plan
  • Fats, Oil and Grease Management Program
  • Lift Station and Force Main Operations and Maintenance Program
  • Gravity Sewer System Operations and Maintenance Program
  • Inter-Jurisdictional Agreement Program
  • Continuing Sewer Assessment Program for the Wastewater Collection and Transmission System
  • Infrastructure Rehabilitation Program for the Wastewater Collection and Transmission System 

Priority Rehabilitation Projects

Memphis has identified areas for priority assessment and rehabilitation based on the:

  • age of the infrastructure,
  • frequency and volumes of the SSOs,
  • proximity to Clean Water Act 303(d) listed streams
  • proximity to environmental justice communities. 

Memphis has agreed to complete all rehabilitation projects in the priority areas within six years and seven months after EPA’s approval of the Infrastructure Rehabilitation Program. The Infrastructure Rehabilitation Program contains the programs for the rehabilitation of the gravity line, manholes, lift stations and force main.  

Most of the priority areas include areas near downtown Memphis where most pipes are in excess of 50 years old

Memphis has identified three specific locations where interceptors will be replaced due to the critical nature of the infrastructure and potential discharges of large volumes of untreated wastewater if the infrastructure should fail. 

The priority projects also include four additional rehabilitation projects that rehabilitate manholes and lining of existing interceptors.
The initial priority areas represent approximately 10 percent of the wastewater collection and transmission system.

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Pollutant Reductions

  • over 9.3 million gallons of raw sewage per year
  • 14,500 pounds per year of total suspended solids (TSS)
  • 13,890 pounds per year of biological oxygen demand (BOD)
  • 2,254 pounds per year of total nitrogen
  • 322 pounds per year of total phosphorus

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Health and Environmental Effects

  • 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.  A High BOD indicates 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. 
  • Total Nitrogen is the sum of organic nitrogen, ammonia and ammonium.  Nitrogen is an essential element for primary production.  Excess nitrogen can lead to eutrophication of a water body due to the excess growth of aquatic plants.  Excess aquatic plants on the water’s surface will impede sunlight in the water column, and can result in hypoxic waters (i.e. insufficient oxygen in water to support aquatic life).
  • Total Phosphorous is an essential element for primary production and much like nitrogen; excess amounts can lead to eutrophication and hypoxic waters that are unable to sustain aquatic organisms.   

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Civil Penalty

Memphis will pay a civil penalty totaling $1,290,000 to resolve CWA violations as follows:

  • $645,000 to the U.S.
  • $645,000 to the State of Tennessee in the form of state projects.

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State Partners

The state of Tennessee and the Tennessee Clean Water Network (intervening plaintiff) joined EPA in this consent decree.

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Comment Period

The settlement, lodged in the U.S. District Court for the Western District of Tennessee, 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:

Benjamin Bahk
U.S. Environmental Protection Agency
Office of Civil Enforcement
1200 Pennsylvania Ave. NW Mail Code 2243A
Washington, DC 20460
Bejamin Bahk (

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