The Environmental Services Division of Public Works (ESD) is comprised of ten sanitary sewer districts. ESD has four permitted wastewater discharge points: Main Wastewater Treatment Plant (WWTP), Combined Sewage Treatment Plant (CSTP) 2, CSTP 5, and CSTP 6.


Main Treatment Facility

The main plant treats 4 to 5 million gallons per day of wastewater during normal operation. Wastewater originates from homes, industry, and commercial districts. Three districts have combined sanitary and stormwater sewer systems. These are known as Combined Sewer Districts.

For more information about the wastewater treatment process, view the brochure After Flushing, Where Does It Go?

Do you want to take a virtual tour of the WWTP? 

Join Andrea, the former Water Resources Program Coordinator, on the tour and learn about the WWTP treatment processes! Click HERE to watch.

Combined Sewer Treatment Plants (CSTP)05232018154127_001 

Combined sewers contain both stormwater runoff and sanitary sewerage. The CSTP treatment facilities are utilized during high run-off events. The dilute wastewater in the CSTP is either sent to the main plant for treatment after the run-off event or can be treated on-site and discharged. The CSTPs have been instrumental in reducing/eliminating sewer back-ups in homes or businesses. The image was taken in 1978 during CSTP 6 basin construction. 

lift stationLift Stations

There are numerous lifts stations throughout the city. They aid the flow of the wastewater to the plant. There are three lifts stations that include overflow ponds. When used, the overflow ponds must be pumped and sent to the treatment plant as soon as possible.

Wastewater Treatment Plant Historical Timeline

Back in 1910, Superior had over 40,000 people. For decades there was no sewage treatment.


1880 The first sewer pipes in Superior were built.

1891 The city had over 40 miles of street sewers with some up to 10 feet and 4 inches in diameter. The larger pipes were some of the largest in the country at that time.

1958 City Superior WWTP facility opened.

1976 Installation of Secondary Treatment that includes aerobic organisms.

2012 Ultraviolet (UV) light disinfection upgrade completed.

Only flush the 3 P's!

Materials that do not immediately break down such as toys, feminine hygiene products, and “flushable” wipes, can easily cause a  blockage in sanitary sewer pipes. These clogs cause backups in basements or overflows.