The discriminant analysis (DA) method was used to differentiate and classify the water quality of three major rivers in South Florida. In this study, DA was used to assess the water quality and evaluate the spatial and temporal variations in surface water quality in South Florida. DA, as an important data reduction method, was used to assess the water pollution status and analysis of its spatiotemporal variation. It was found by the stepwise DA that five variables (chl-a, dissolved oxygen (DO), total Kjeldahl nitrogen (TKN), total phosphorus (TP) and water temperature) are the most important discriminating water quality parameters responsible for temporal variations. Spatial variation in water quality was also evaluated and identified five variables (TKN, TP, ammonia-N, magnesium, and sodium) and seven variables (chl-a, DO, TKN, TP, ammonia-N, magnesium, and chloride) as the most significant discriminating variables in the wet and dry season, respectively of three selected rivers in South Florida. It is believed that the results of apportionment could be very useful to the local authorities for the control and management of pollution and better protection of important riverine water quality.