Optimization of parameters used for freshwater survey

The presence of redundant information in the 13 usual parameters used for water quality control is verified by means of principal component analysis (PCA). Four parameters (pH, conductivity, COD and total plate count at 20°C) produce a classification pattern very close to the ones obtained with eight and 13 parameters. Data collected after 20 years describe an environmental situation very close to that described in 1972.