After a heavy rainfall, the amount of combined water and raw sewage – known as combined sewer overflow, or CSO – that enter the city’s waterways can often force public officials to warn against water sports like swimming, kayaking and rowing because of the risk of contamination by bacteria.
In fact, the latest version of the Integrated Water Quality Monitoring and Assessment Report by the Department of Environmental Protection on the U.S. state identifies sewage overflows as one of the main causes of the deterioration in water quality in the Allegheny and Monongahela basins, due to the spread of pathogens such as E. coli.
This explains the determination of Allegheny County Sanitary Authority (ALCOSAN), the regional public utility, to reduce combined sewer overflow as much as possible, especially given the fact that Pittsburgh, which accounts for a quarter of the county’s residents, is located at the meeting point of three rivers, the third one being the Ohio River.