Multivariate statistical methods such as factor analysis (FA) and cluster analysis (CA) were applied to identify the main factors
and pollution sources affecting on the water quality of Danube River and to evaluate spatial and temporal similarities or
dissimilarities among the sampling sites and monitoring periods. Water quality of 14 parameters has been considered in four
sampling stations during 1 year period. The results of factor analysis specified three factors representing 64.369% of the total
variance in water quality. The main differences are related to domestic wastewater, industrial discharge, and agriculture activities
from agricultural area. Hierarchical spatial CA revealed two different groups of similarities between the sampling sites, reflecting
different pollution levels in the river water quality. Hierarchical temporal CA showed that the temporal variations in the river water
are not relying on the local climate.