Water quality in the tietê river watershed, são paulo state, Brazil

The monitoring of surface water quality aims to identify problems and seek solutions to improve the quality of life and environmental health. Objective: To evaluate the water quality in the Tietê River Watershed in the metropolitan region of São Paulo. Methodology: The water quality parameters data of 48 samples obtained in the São Paulo State Indoor Water Quality Report of the São Paulo State Environmental Company in 2018 were evaluated. Eight monitoring points were analyzed. Nine parameters of water quality (total solids, water temperature, turbidity, biochemical oxygen demand, total phosphorus, total nitrogen, dissolved oxygen, hydrogen potential and thermotolerant coliform) were used to calculate the Water Quality Index (WQI). Results and Discussion: Water quality ranged from Excellent (WQI: 80 to 100) to Good (WQI: 52 to 79), during 2018, at collection points located in an environmental preservation area with little influence from the urban area and the absence of effluent discharge, these factors provide better water quality in these stretches of the river. The quality of the water varied from Bad (WQI: 20 to 36) to Poor (WQI: 0 to 19) in the stretches of the river with urbanization and industrialization. Conclusion: The water quality in the Tietê River Watershed is poor or very poor in most part of the river that crosses the metropolitan region of São Paulo, indicating the influence of land use and occupation in the watershed that is predominantly urban. The release of treated effluents and in natura sewage changes the quality of the water in the region, which has its use compromised mainly due to the high load of organic matter and the presence of microorganisms that indicate fecal contamination.