Michigan Map Rouge River National Wet Weather Demonstration Project
The Rouge River Project
Bringing the river back to life!
Home Search About the Rouge Project Contact Us

Combined Sewer Overflow Control ProgramBrief SummaryOverview Description of the CSO Control ProgramWhat are CSOs?CSO Demonstration ProjectsMDEQ Criteria for Success in CSO TreatmentTechnical Papers and Professional Presentations on CSO Control ProgramCSO Technical Reports - Monitoring and OtherEmerging Information on CSO Facility PerformanceEnvironmental Results

Combined Sewer Overflow
Control Program


The Rouge River National Wet Weather Demonstration Project (Rouge Project) has been an unqualified success story in many ways including the control of combined sewer overflows (CSOs). This has been confirmed by independent sources. During the latter part of 2001, USEPA's Office of Inspector General (OIG) conducted a nationwide audit of the national CSO control program. The OIG issued their final Evaluation Report on "Wastewater Management - Controlling and Abating Combined Sewer Overflows" in August 2002. The following is a quote from that report about the Rouge Project’s CSO control program and the watershed approach being utilized:

Rouge River Project a Blueprint for Success
The Rouge River National Wet Weather Demonstration in Michigan is an excellent
example of how utilizing a watershed approach can help to achieve water quality
goals more efficiently. We have previously described in this report some of the successful results that have been achieved by this project.”

The restoration of the Rouge River began by focusing on the primary public health pollutant threat and source: combined sewer overflows. At the start of the program, 168 CSOs were identified, with a tributary service area of approximately 59,300 acres (approximately 20% of the watershed).

CSO controls are being implemented in the Rouge Project through three phases as established by National Pollutant Discharge Elimination System (NPDES) permit:

  • Phase I: elimination of raw sewage and the protection of public health for approximately 40 percent of the combined sewer area
  • Phase II: public health protection for the remaining combined sewer area
  • Phase III meet water quality standards in the Rouge River

Under Phase I, six communities separated their sewers and eight communities constructed 10 retention treatment basins. Each of these basins is sized for different design storms and several employ innovative technology. These CSO basins also incorporate a variety of additional features or variations in compartment sizing and sequencing in an effort to improve their effectiveness. The retention treatment basins capture most wet weather flows for later conveyance to the Detroit POTW for treatment. Flows from very large wet weather events that are not captured by the retention treatment basins receive screening, skimming, settling, and disinfection prior to discharge. These CSO control projects have effectively eliminated or controlled the discharge of untreated sewage from approximately half of the watershed CSOs.

Working with the local communities, the Michigan Department of Environmental Quality (MDEQ) established rigorous "Criteria for Success in CSO Treatment" to evaluate whether the CSO basins meet the Phase I and II goals of elimination of raw sewage discharges and protection of public health and the Phase III goal of achieving water quality standards. The development of an evaluation process provided an innovative forum for stakeholders to collaboratively establish objectives for CSO controls within the goals of urban watershed restoration. Since wet weather control is expensive, having a well defined, technical evaluation process to determine compliance with regulatory requirements is important.

A detailed evaluation study of each of the CSO control basins was completed to examine the performance of the facilities and the resulting water quality impacts of their discharges. The results of the evaluation study, coupled with efforts to control storm water and other pollution sources in the watershed, has provided valuable technical information for use in establishing the basis for deciding on the Phase II and Phase III CSO control program on the remaining CSO sources in the watershed. In addition, the evaluation of design storms and control technologies has provided valuable technical information for communities embarking on such controls in other watersheds in the country.

As the CSO control program has been implemented, additional valuable lessons were learned in the success of the control technology selected at the various basins. Standard operation and maintenance procedures are ensuring that the basins are meeting effluent limits and keeping the basins as good neighbors to surrounding land uses, which include nature centers, a golf course, and recreational facilities. A very noteworthy finding was that while the technology was selected, installed and operated so as to meet the Phase I objective (elimination of raw sewage and the protection of public health), it was learned that the Phase III objective (meeting water quality standards in the Rouge River) was also achieved in many instances.

USEPA's 1994 National CSO Control Policy has been fully implemented through the Rouge Project.

It is very important to note that the CSO control program, while at the heart of the Rouge Project, is but one element of the overall Rouge River restoration effort. The impressive improvements in water quality and recreational use in the Rouge River can be attributed to the multitude of other Rouge Project programs including illicit connection elimination, storm water management activities, and developing better public, industry and community awareness of pollution control and prevention. These programs and others are all part if the watershed approach being successfully implemented in the Rouge River watershed. For more information on the watershed approach being utilized click here.

The Rouge River Wet Weather Demonstration Program has been successful in identifying efficient and cost effective CSO basins for control of combined sewer overflows. The wisdom of controlling CSOs at remote locations versus trying to convey all of the combined sewage at one time to the central treatment plant was confirmed. Combined sewer overflow pollutant loads to the river have been cut by 90 to 100 percent during most wet weather events. Demonstration basins, built to a smaller size than what would have been required by presumptive criteria, have reduced release of pollution to the river with excellent environmental protection results. Protection of human health, elimination of the discharge of raw sewage, and meeting water quality standards have been achieved, with the exception of TRC, which is still being investigated. Phased implementation has allowed lessons learned to be used in subsequent phases, affording greater efficiencies in developing and implementing controls for the remaining CSOs with a very large savings in capital expenditures. The completed basins are controlling overflows at a rate of approximately 4 billion gallons per year with outstanding water quality and aesthetic improvements and increased recreational usage in the Rouge River.


Last Updated: 6/22/2012

Please address all comments and suggestions about the contents of this Web page to doehelp@co.wayne.mi.us.

The Rouge River National Wet Weather Demonstration Project is funded, in part, by the United States Environmental Protection Agency (EPA) Grants #XP995743-01, -02, -03, -04, -05, -06, -07, -08, -09 and C-264000-01.