A study conducted in the summer of 2021 by Fondation Rivières validated the swimming potential of 9 sites along 55 km of the Châteauguay River. The bacteriological quality of water was analyzed using both E. coli counts after laboratory culture and a new rapid analysis technology (ColiMinder, VWMS). This dataset contains all the data of E. coli counts after laboratory culture carried out as part of this project. /A study was conducted in the summer of 2021 by Rivers Foundation to validate the bathing potential of 9 sites along 55 km of the Châteauguay River. The bacteriological quality of the water was analyzed using both E. coli counts after incubation and a new rapid analysis technology (ColiMinder, VWMS). This dataset contains all of the E. coli counts after incubation perfomed during this project.