Water quality of the São José stream network used for water supply to the city of Chapecó, SC, Brazil

The objective of this study was to evaluate the water quality of the São José stream which supplies the city of Chapecó, southern Brazil, considering some physical-chemical and microbiological indicators of water quality. The samples were collected monthly from June 2007 to March 2008 at four points of the stream. The sampling points in the
watershed were distributed as follows: point 1 – the highest watershed represents both the urban and the rural contribution; point 2 – the contribution of pig raising activity; point 3 – represents the urban contribution; and point 4 – located near the Casan reservoir, is the sum of all points upstream. The measured parameters were excremental matter, DO, turbidity, pH, total-P, nitrate, ammonia, BOD and metals Cu, Zn and Pb. The results demonstrated the occurrence of values, for some parameters, above the permitted by the Conama Resolution 357/2005 for water class 1, mainly at monitoring points 2 and 3. The implementation of the water quality index (IQA) allowed the classification of points 2 and 3 as of poor quality, and points 1 and 4 as of acceptable quality.