METHOD FOR ESTABLISHING QUALITY REFERENCE VALUES AND SURFACE WATER USE CLASSES IN WATERSHEDS IN THE STATE OF SANTA CATARINA, BRAZIL

Abstract

The knowledge about water quality through the determination of its descriptors is fundamental to establish water resource management policies. This work suggests a simple and practical method to determine values associated with water quality descriptors. For this purpose, it was necessary to use the results accumulated over 10 years of surface water quality monitoring from watersheds in Santa Catarina State. Taking into account the five classes of use already established in federal legislation (CONAMA Resolution nº 357/2005), the limits for each class were determined based on the distribution of the values of the parameters under study. The median was used to establish the quality reference values and the 60 th percentile as the upper limit to consider the descriptor value as acceptable. The method presented is easy to apply, and the calculated values, compared to the current legislation, are more restrictive when it comes to suggesting good water quality.