Thorold Combined Sewer Overflows at Niagara Region Facilities

Data presented here is updated every three months. The data contains records from
April 01, 2022 to March 31, 2023.

Volume is measured in megalitres. (1 megalitre = 1 million litres)

CSO Location Date of Overflow Volume (ML) Reason for Overflow
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Nov 30, 2022 0.415 ML Heavy Precipitation
Black Horse SPS
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Jun 22, 2022 N/A ML Heavy Precipitation

Historical Overflow Data for Thorold

Total Overflows: 5
Total Volume: 4.202 ML
Total Overflows: 1
Total Volume: 0.389 ML
Total Overflows: 0
Total Volume: N/A ML

Overflows contain mostly Storm Water

While the volume of an overflow may seem large, the amount of untreated sewage present in the overflow is small when compared to the amount of stormwater or snow melt.

Niagara typically treats about 80,000 megalitres of sewage each year.  The vast majority of wastewater discharged into the sewer system receives full treatment and only a small percentage of this sewage overflows. These overflows usually only occur during periods of heavy rain or during seasonal snow melts.

Historical Data

If you require more detailed information about a specific combined sewage overflow, you can contact the water & wastewater division.

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