The theme on physicochemical monitoring of rivers and rivers presents data from all stations in networks monitoring water quality in rivers in Quebec and the St. Lawrence River. The purpose of networks for monitoring general water quality is to characterize, using current physicochemical and bacteriological parameters, the quality of water in spatial terms and to monitor the evolution of this quality over time. For the regular monitoring of the general quality of river and river water, the parameters measured are: total phosphorus, total nitrogen, nitrites and nitrates, ammonia nitrogen, chlorophyll a, pheopigments, faecal coliforms, faecal coliforms, turbidity, suspended matter, pH, conductivity, dissolved organic carbon and temperature. This data is used to calculate the Bacteriological and Physicochemical Water Quality Index (IQBP), a water quality classification index. The data set on physicochemical monitoring of rivers and rivers also includes the drainage areas of some of the stations. The attribute table provides a compilation of land use by category for the last year available at the time the data was generated. Follow-up is carried out annually.**This third party metadata element was translated using an automated translation tool (Amazon Translate).**

This dataset presents the physicochemical and bacteriological evolution of water in rivers in southern Quebec and the St. Lawrence River. The 10-year (2015-2024) temporal trends on the rivers and in the river present the evolution of the ambient concentrations of physicochemical and bacteriological parameters, while the 20-year (2004-2023) time trends on the rivers present the evolution of loads and concentrations adjusted for the flows of physicochemical and bacteriological parameters. *Note that the temporal trends in total phosphorus have been invalidated due to an underestimation of concentrations caused by analytical biases that affect the majority of the data targeted for calculations. Therefore, they are not broadcast.**This third party metadata element was translated using an automated translation tool (Amazon Translate).**