Sediments samples of the Dobczyce Reservoir(South Poland)were taken in three successive years(2004-06)at 17 points,analyzed for 12 elements by atomic absorption spectrometry.Substantial variations in elemental composition due to hydrological and environmental reasons were found.The use of statistical and chemometric tools enabled objective and effective analysis of the data obtained,both in case of long term observations as well as in terms of interpretation of incidental changes in metal concentrations.The proposed methodology can be useful in: a)dividing monitored territories(lakes,rivers,catchments)into similar and dissimilar areas; b)distinguishing between typical and non-typical contaminants distribution; c)reducing the number of essential analytes and sampling points that should be controlled in the future,without loss of important environmental information.