Our paper presents the results of determining the contents of trace elements (TEs) in the surface water and bottom sediments of Lake Wadąg in Poland’s Masurian Lakeland. The samples were collected in August 2015. Trace elements were determined in samples using inductively coupled plasma with mass detection (ICP-QQQ). To assess the chemical composition of surface water, use was made of multivariate statistical methods of data analysis: cluster analysis (CA) and principal component analysis (PCA). The use of pollution factors such as the geochemical index (I_geo), pollution index (PI) and pollution load index (PLI) made it possible to distinguish groups of elements allowing for the analysis of spatial variation of bottom sediment in the studied area. Results showed increased concentrations of Hg among all bottom sediment sampling sites. The highest concentrations of determined elements occurred in sampling site No. 5. Surface water was characterized by Hg, Pb and Cu concentrations higher than those of Pregoła’s basin. Yet the comparison with average concentrations of these elements in Polish lakes revealed the increased concentration of Hg.