Assessment of surface water quality in the city of rio claro/sp – brazil

The aim of this study was to perform a diagnosis of surface water and sewage system of the municipality of Rio Claro, State of São Paulo, Brazil. For this, data of surface water quality parameters of five sampling points (located on the Corumbataí and Ribeirão Claro rivers) were analyzed. In addition, the effluent quality and efficiency of two municipal sewage treatment plants were evaluated. Finally, the data collected were compared with the values established in environmental legislation. Regarding the parameters of water quality, the parameters phosphorus, Escherichia coli, dissolved iron and dissolved aluminum were the ones that presented the most values outside the limits established by the legislations. Besides, at some sampling points, the biochemical oxygen demand and dissolved oxygen concentrations were in disagreement with the values indicated in the legislation. However, the Water Quality Index was rated as good at almost all sampling points, except for a point classified as regular. Regarding the effluent emission standards, the data analyzed are in accordance with the legislation. With the results, it was possible to realize that the sampling point that had worse quality is what is located downstream of the municipality.