Land use impacts on water resources of the Manacás Lake Basin, Minas Gerais, Brazil

The 134.68 ha campus of the Federal University of Juiz de Fora (UFJF) is in urban area impacted by new developments. The population of 27,600 consumers causes the loss of green areas and generates increasing waste and sewage water. This study evaluated the impact of UFJF Campus activities on water quality, emphasizing the Manacás Lake Basin (MLB). The evaluation was based on five monitoring points: a spring (P1) and the four mouths of the streams that flow into Manacás Lake (P2 to P5). Water samples were collected monthly between November 2013 and October 2014, and pH, DO, COD, Conductivity and Turbidity were analyzed. The results showed that the DO increases from the spring (P1) to the mouth (P2), with low values at the other points, and a median of 1.3 mg L-1 at P5. COD does not follow a pattern, registering medians higher than 6 mgO2 L-1 at all points, highlighting P4 with 25.5 mgO2 L-1, the sub-basin which contains most of the Labs. Worse turbidity was found at P5, with 39.42 UNT, coinciding with the sub-basin most affected by construction. Conductivity gradually increased from P1 to P2, and medians were not statically different for P3, P4, and P5. Manacá Lake is Class 2 according to CONAMA resolution Nº 357/2005, but the results showed that the DO at P4 and P5 has values of Class 4 water, with frequent anaerobiosis.