Last updated: 03/05/2021
Heavy rain can cause Toledo's combined sanitary and storm sewer collection system to reach capacity. A Combined Sewer Overflow (CSO) can occur in one or more locations within Swan Creek, Ottawa River and/or the Maumee River where the City is permitted to discharge during wet weather.
The public will be notified within four hours of a documented CSO event. The public will be provided with supplemental information within seven days after the conclusion of a documented CSO event. The City will provide a summary of the previous year’s CSO discharges by May 1 each year.
Latest Combined Sewer Overflow Reports
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Understanding CSOs
In older areas of Toledo, portions of the sanitary sewer and stormwater collection systems are combined. During heavy rain events, combined sewers can become completely filled with rainwater, causing raw sewage to overflow into Swan Creek, the Ottawa River, and Maumee River.
Where are the CSOs located?
During heavy rain events, portions of the system that have combined sanitary and storm sewers can become completely filled with rainwater, with the water having nowhere to go but to overflow into the waterways. These points of relief are called Combined Sewer Overflows and are located along Swan Creek and the Ottawa and Maumee Rivers.
How do CSOs affect the Toledo community?
The City is permitted to have a limited number of CSOs in order to protect public health. Without Combined Sewer Overflows, the incidence of sewer water backups into roadways and basements would be greatly increased.
How much untreated sewage is in these outfalls?
CSOs consist of a combination of untreated, but highly diluted, sewage and storm water. These overflows are regulated by the Ohio EPA and on average contain less than 25 milligrams per liter of suspended solids (waste material).
What is the impact of the CSO outfall on public health?
Overflows are meant to protect public health by reducing backups into basements during heavy rains by relieving pressure on the system at specified locations.
What is the impact to our watershed from these outfalls?
Both the incidence of outfalls and volume will be significantly reduced upon completion of the TWI program in 2020. Combined sewer overflow events per location will be reduced on average from 34 to 3 annually. There will be on average 650 million gallons less pollution entering our waterways each year.
What can I do to help reduce water pollution?
Individual households and businesses can combine with others to make a huge difference in water quality through sustainability practices that are sensible and cost-effective.
Improving our Sewer System
Toledo Waterways Initiative
The City of Toledo is reducing both the frequency and volume of Combined Sewer Overflows (CSOs) through the Toledo Waterways Initiative (TWI). When TWI is complete in 2020, we will have an 80% reduction in combined sewer overflow volume, resulting in 650 million gallons less pollution on average from entering the waterways each year.
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