Water quality of the Bonitinho stream in the Formoso village, a nature reserve in the state of Mato Grosso-Brasil

Resumen

This article discusses the water quality found in the Bonitinho stream nature reserve, located on the Formoso river in Tangará da Serra, Mato Grosso. The objective was to evaluate the water quality of the Bonitinho stream from some variables relevant to the classification of surface waters according to Resolution 357/2005 of the National Council for the Environment (CONAMA), for class 1 water rivers. Bonitinho rises to the surface from a cave, in which the water collection system to supply the villages of the Rio Formoso Indigenous Land is installed. Located in the Brazilian Cerrado region, the stream in question is located in an area of natural preservation, that is, the indigenous reserve in accordance with the national law. Use information from a database from the Water Quality Laboratory of the University of the State of Mato Grosso, Barra do Bugres Campus, where it is reported that the water samples for analysis were collected monthly, always on the 15th, during a hydrological cycle complete, in sampling for 12 consecutive months. The results of each variable were grouped according to the dry period (May - October) and rain (November – April). Each water sample was analyzed in triplicate, the result being expressed as the average of the triplicates, generating a set of 12 results for each variable. After organizing the data, they were submitted to normality analysis, followed by appropriate statistical tests for each variable. The water quality was considered good, however the results for the variable Thermotolerant Coliforms extrapolated the maximum limits for Class 1 fresh water, providing the other elements within the potability standard for human consumption. It is concluded that even springs from preserved areas are related to temporal variations, revealing the possibility of waters that do not comply with normative standards.