“…The methodology uses the physical–chemical parameters of surface water to assess and quantify the quality of any surface water body, based on the standards of Hungary ( MSZ, 2010 ), which is in harmony with the Water Framework Directive of European Union ( WFD, 2000 ). The following steps were employed to carry the sampling methodology accordingly: first, the typology of the water body was established, followed by the selection of the cluster of water quality class based on threshold values specified by the Hungarian National Standard ( MSZ, 2010 ) and then compared of a two-by-two strategy, followed by the aggregation of weighted indices obtained from the correlation of physical–chemical matrices and AEI ( Németh et al, 2017 ). The surface water quality categories can be ranked into five different classes, according to Németh et al (2017) from 1 to 5, simply based on the threshold values of physical–chemical water quality parameters, according to the Hungarian National Standard ( Table 1 ).…”