%0 Journal Article %T Calibration of water quality index (WQI) based on Resolution no 357/2005 of the Environment National Council (CONAMA) Calibra o do ¨ªndice de qualidade da ¨¢gua (IQA) com base na Resolu o no 357/2005 do Conselho Nacional do Meio Ambiente (CONAMA) %A Daiane Lautert Moretto %A Ruben Edgardo Panta %A Adilson Ben da Costa %A Eduardo Alexis Lobo %J Acta Limnologica Brasiliensia %D 2012 %I %X Environmental monitoring studies in the Hydrographical Basin of Pardo River, RS, Brazil, in the time series from 2007 to 2009, showed no agreement between the water quality evaluation obtained through the Water Quality Index (WQI - NSF), which ranged from "regular" to "good", and the Environment National Council (CONAMA) Resolution 357/2005, which was bad ("class 4"), highlighting as critical variables for this classification the thermotolerant coliforms and the phosphate concentration, indicating process of water eutrophication, related to the large amount of nutrients and organic load from domestic sewage and excess fertilizers used in agriculture. AIM: This research aimed to calibrate the WQI - NSF for the Pardo River Basin, based on the CONAMA Resolution 357/2005. METHODS: Using the database (2007 a 2009) from the Laboratory of Limnology of the University of Santa Cruz do Sul (UNISC), RS, corresponding to the environmental monitoring studies realized in the Hydrographical Basin of Pardo River new weights of the relative importance of the variables used to calculate the WQI were attributed, by means of principal component analysis. RESULTS: There was a significant agreement between the results of the assessment of water quality using the CONAMA Resolution 357/2005 and the new WQI calibrated. CONCLUSION: The results certify the use of the calibrated WQI in environmental monitoring programs in lotic systems belonging to Gua¨ªba Hydrographical Basin, RS. Estudos de monitoramento ambiental na Bacia Hidrogr¨¢fica do Rio Pardo, RS, Brasil, na s¨¦rie temporal 2007 a 2009, mostraram que n o h¨¢ concordancia entre a avalia o da qualidade da ¨¢gua obtida atrav¨¦s do ¨ªndice da Qualidade da ¨¢gua (IQA - NSF), que oscilou entre boa e regular, e da Resolu o 357/2005 do Conselho Nacional de Meio Ambiente (CONAMA), que foi ruim (classe 4), destacando como vari¨¢veis cr¨ªticas para esta classifica o os coliformes termotolerantes e a concentra o de fosfato, indicando processos de eutrofiza o da ¨¢gua, relacionados ao aporte de nutrientes e carga organica oriundos de esgotos dom¨¦sticos e de fertilizantes utilizados na agricultura. OBJETIVO: A presente pesquisa objetivou calibrar o IQA - NSF para a Bacia Hidrogr¨¢fica do Rio Pardo, baseando-se na Resolu o 357/2005 do CONAMA. METODOLOGIA: Usando o banco de dados (2007 a 2009) do Laborat¨®rio de Limnologia da Universidade de Santa Cruz do Sul (UNISC), RS, correspondente aos estudos de monitoramento ambiental realizados na Bacia Hidrogr¨¢fica do Rio Pardo, novos pesos da importancia relativa das vari¨¢veis usadas para calcular o I %K ¨ªndice de Qualidade da ¨¢gua (IQA) %K eutrofiza o %K Bacia Hidrogr¨¢fica do Rio Pardo %K RS %K Resolu o 357/2005 do CONAMA %K Water Quality Index (WQI) %K eutrophication %K Hydrographical Basin of Pardo River %K Resolution 357/2005 of CONAMA %U http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2179-975X2012000100004