The main purpose of this work was to study the surface water quality behavior, continuously throughout the time, at the headwater watershed of the Grande River, MG. The watershed drains into Grande River area of 687 ha and is enclosed by the Mantiqueira Mountains. The samples were collected at six points in Lavrinha Stream, main tributary of the watershed, from May 2006 to January 2007, with a total of seven evaluations for each point. Current watershed land use map was developed through GPS device, based on field observations. The parameters evaluated were: hydrogen potential (pH), Dissolved Oxygen (DO), electric conductivity (EC), salinity, temperature, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), nitrate (NO3-), ammonia (NH3), phosphorous (PO4), turbidly, total soil, total dissolved soil (TDS), fecal coliform (Escherichia coli), total coliform. Water Quality Index (WQI), proposed by "Minas Gerais State Water Resources Institute" (IGAM), was calculated for all samples, classifying the water quality class according to CONAMA Resolution 357/05. The environmental conditions reflected on WQI values as well as on CONAMA water quality classification. It was evidenced that the main parameter of the critical situation of the water quality at watershed was the fecal and total coliform, which is associated to livestock. Although less important than coliform, DO and BOD are also limiting parameters at watershed.
Water resources; WQI; water quality; Lavrinha Stream Watershed
