Mining, as well as other anthropogenic changes can have big environmental impacts by changing the pristine characteristics of different biomes. Know and understand their potential effects assists in proposing actions to control and protection of environmental resources, especially of aquatic ecosystems. The objective of this study was to evaluate the ecotoxicological effect caused by the environmental impacts of mining in the river watershed Monkeys, under water and sediment, added to the physical-chemical studies conventional and quantification of metals in different seasons evaluated in two collections. The basin had severe degradation of evidence. Conventional parameters are not substantially altered, and no acute ecotoxicity in water. However the pellet is already at a high concentration of various metals, as well as chronic ecotoxicological effects. The occurrence of these chronic events, even in the face of normal physical-chemical results, shows the importance of these studies both in the water and sediment. The differences in the results of the two campaigns showed that the seasonally influenced the availability of organic matter in the sediment and / or adduced by leaching.