Evaluation of water quality in a dam used for public supply in the municipality of Sorocaba/SP

Abstract

Water is an essential resource for the existence of life on Earth, Brazil has a vast water potential, however its spatial distribution does not coincide with the largest population agglomerations, which consequently requires managers more efforts to overcome water scarcity. Reservoirs are implemented in order to meet the water demand for the storage of this resource. However, the anthropic activities developed in the context of watersheds have influenced their quality and storage capacity. In this sense, this study aimed to evaluate the water quality in the Clemente dam located in the metropolitan region of Sorocaba. A water sampling was performed once a month between January 2016 and December 2019, and the analysis of physical-chemical and biological parameters was performed, as well as the Water Quality Index (WQI), and finally, the data were evaluated by means of Principal Component Analysis-PCA. Although the results obtained showed little variation in the physical-chemical and biological parameters over the years, it was possible to notice a reduction in the water quality of the spring. The WQI obtained over the period was considered "good", "excellent" and "regular". The PCA indicated that more than 70% of the data variance were explained by the first three components, with significant contribution of dissolved oxygen, temperature, phosphorus, BOD and Thermotolerant coliforms, and the last three factors are related to pollutants of domestic and industrial origin.