Understanding the Impact of Combined Sewer Overflows
By Todd Sattison, Superintendent of Water Pollution Control
Recently during a heavy rainfall, the City of Auburn’s Department of Water Pollution Control reported Combined Sewer Outlet (CSO) overflows. During an overflow event, minimally treated and/or untreated sewage spills directly into the receiving stream, causing elevated regulated pollutant levels for a few days. While this has no effect on drinking water within the City of Auburn, the public should be aware and avoid ingesting, swimming, wading and participating in any water activities at Cedar Creek during CSO alert periods.
Our department—which includes a Class III Municipal Wastewater Treatment Facility, as well as both separated and combined sewers—protects the health and well-being of the community and downstream users. We have several measures in place to ensure clean and safe effluent waters, including regularly monitoring Auburn’s four CSOs:
- Main wastewater treatment facility on the west side of Cedar Creek
- Cedar Creek at 7th Street
- Eckhart Park near Grandstaff Drive
- Auburn Drive
However, CSO overflows can still happen, particularly during heavy fall and spring rainfalls. Snowmelts can also make it impossible for the treatment plant and sewers to handle the increased flows. Rest assured, though, the amount of sewage is minimal—particularly since the water is treated before it is released.
When current or forecasted weather threatens to cause a CSO overflow, we will post a cautionary alert on the city’s website, and our Facebook and Twitter accounts. These alerts will remind the public of the potential for untreated sewage being discharged into the receiving stream.
The city has an ongoing Long-Term Control Plan to separate our combined sewer outlets and eliminate three of the CSOs. This complicated process will continue to be implemented in phases over the next several years.