Water quality assessment of a multiple-use reservoir in southeastern Brazil: case study of the Vargem das Flores reservoir

This paper presents an analysis of surface water quality of the sub-basin of the Vargem das Flores reservoir, which is used for public water supply to the metropolitan station of Belo Horizonte (RMBH), Minas Gerais. A total of 5415 data items and eight water quality parameters, common to all monitoring stations, from the period 2002 to 2018 were assessed using multivariate and nonparametric statistical tests. The water quality parameters that were assessed included color, biological oxygen demand (BOD), total phosphorus, total manganese, dissolved oxygen (DO), total suspended solids, and turbidity showed violations of the maximum concentrations allowed in most of the tributaries to the reservoir. Despite this, the stations inside the reservoir appeared to have good quality water, particularly at Station 1, whose water is designated for human consumption. The results of a cluster analysis showed that the water quality of the sub-basin of the Vargem das Flores reservoir is in a condition of environmental degradation relative to the water quality of the water courses that feed the reservoir. The intense and disorderly development in the sub-basin and the discharge of untreated or poorly treated wastewater effluents are factors that can lead to sediment supply and cause the silting and contamination of the water.