The watershed is located in the center of São Paulo State, Southeast of Brazil. The coordinates are: Lat. 22º 10' 08,5" S; Long. 47º 57' 11,7" W. The drainage density is 0.75km/km2. The maximum altitude is 800m. Basin declivity is 0.00575m/m. The local climate is characterised by alternating dry and wet periods, the wetter period falling in summer and autumn, and the winter and spring seasons being mainly dry. Annual precipitation is around 1500 mm per year. Temperatures are typically between 15 °C and 17 °C during the coldest winter month (July); in the warmest summer month (January), water temperatures between 21 °C to 23 °C are recorded. Potential evapotranspiration is between 500 mm to 1000 mm per year. According to the Koppen classification, the climate is described as ‘warm with a dry period’. The watershed is dominated by holocenic sandy sediments. In the lowland areas, hydromorphic and organic soils predominate. Soils derived from basalt intrusion occur in some areas of the watershed, as red soil hotspots. The natural vegetation is characteristically a savanna type, the Cerrado, typical of the continental regions of Brazil, consisting of bushes and trees adapted to a long (six months) dry season with periodic fires. Given the hydrogeochemical character of the watershed, the ionic strength and the nutrient content of the water of Lobo-Broa Reservoir are correspondingly low.