The purpose of this study is to assess the water quality of the Canal do Anil basin in Rio de Janeiro by taking account of seasonality, as well as quantitative and qualitative factors, based on a multivariate framework designed for the correlation of parameters and environmental conditions. The methodology involves collecting data from water samples at specific points in the basin. The concept of seasonality is represented on a temporal and spatial scale and based on the seasons, rainfall volume, parameters and water quality index. The results showed a worsening of the water quality from upstream to downstream, with a high concentration of total dissolved solids and turbidity, especially in the downstream channel. There is a tendency for greater dilution or movement of pollutants, depending on rainfall intensity, and a little evidence of a close correlation between the parameters analyzed. Climatic seasonality, related to rainfall and the observed flow rate, has an effect on improving water quality, which is aggravated by the high concentration of domestic and industrial pollution. The lack of basic sanitation in the region, especially a sanitary sewage system and a regular collection of solid waste, leads to conditions of environmental degradation in the Canal do Anil basin.