04/30/2026
Good Afternoon Pekin,
We’ve received several questions from residents about the City’s Combined Sewer Overflow (CSO) Project. Given the scale and importance of this work, we want to provide a clear, straightforward explanation of what this project is, why it’s necessary, and how it is being funded.
What is a Combined Sewer Overflow (CSO)?
A large portion of Pekin operates on a combined sewer system. This means that both rainwater (stormwater) and wastewater from homes and businesses are carried through the same pipes to the wastewater treatment plant.
Under normal conditions, the system works as intended and all water is treated before being released. However, during heavy rainfall, the volume of water can exceed the system’s capacity. When that happens, the system is designed to relieve pressure through controlled overflow points. In these instances, a mixture of stormwater and untreated wastewater can discharge into the Illinois River. These occurrences are called Combined Sewer Overflows, or CSOs.
Why is the project necessary?
CSOs are regulated under state and federal environmental laws, and communities like Pekin are required to reduce the frequency and impact of these events over time. This is not optional—it is part of compliance with the Clean Water Act and the City’s National Pollutant Discharge Elimination System (NPDES) permit, which governs how and when water can be discharged into waterways.
In simple terms, this project is about:
*Reducing the amount of untreated water reaching the river
*Improving the reliability of the sewer system during heavy rain
*Meeting environmental regulations
*Preparing infrastructure to support future growth
What work is being done?
The CSO program has been completed in phases over several years.
Earlier phases focused on expanding treatment capacity at the wastewater plant and improving how the City manages large volumes of water during storms.
This current and final phase includes upgrades to major interceptor sewers and other critical infrastructure. These improvements help move water more efficiently through the system and to the Waste Water Treatment Plant where it can be treated prior to overflow into the river.
How is this project funded?
Like most large-scale infrastructure projects, this work is financed through a combination of long-term planning and borrowing, rather than a single-year expense.
Recent City Council approvals have primarily involved:
*Authorizing funding mechanisms such as low-interest loans through state programs (commonly through the Illinois Environmental Protection Agency), which is the case here.
*Issuing bonds or debt instruments to spread costs over the life of the infrastructure
*Aligning repayment with utility revenues, such as sewer service fees, rather than relying solely on property taxes
This approach allows the City to complete federally mandated improvements now while distributing the financial impact over time in a responsible and manageable way.
Why now?
The Illinois Environmental Protection Agency mandated these improvements as part of prior wastewater treatment plant upgrades. The City is operating under a long-term compliance schedule, and each phase must be completed within established timelines.
Looking ahead -
While projects like this are complex and not always visible day-to-day, they are essential to maintaining public health, protecting the Illinois River, and ensuring Pekin’s infrastructure remains dependable for decades to come.
We appreciate the community’s continued interest as this important work progresses.
