Nowadays the human activity has increased the pressure on surface water quality. The purpose of this study is to assess the environmental quality of the Seman River water (in Southern part of Albania) through a 5-year monitoring program of 14 parameters (pH, DO, EC, TSS, Cl − , 3 NO − , Total-N, Total-P, BOD 5 , Cu 2+ , Ni 2+ , Pb 2+ , Cd 2+ and Temp. ˚C), that determine the environmental status of this waterbody, as well as the application of WQI (CCME) through a multivariable approach. Based on the cluster dendogram results, it can be concluded that during wet seasons such as winter-spring, there are more sediments which influence other physic-chemical parameters, while during dry seasons (summer-autumn) there are more decomposition reactions of elements released by sediments and influenced by temperature. PCA analysis determines whether the groups of factors correlate strongly or not, depending on the internal structures of the groups and variables "heavy" or latent and vary from season to season with differentiated contributions to the water quality. All three factors influence WQI to the extent of 56% in the summer and spring season and 64% and 40% in the autumn and winter season, respectively.

Oil extraction activities in Albania are considered as highly polluting for surface waters, but more for the amount of direct spills in riverine waters. The aim of this study was to assess the surface water quality for a period of 5 years (2014-2018) in four seasons based on different physico-chemical parameters in the Seman River, in Zharreza reservoir and drainage canal, located in the district of Fier, Albania. Seventeen chemical parameters were monitored such as pH, DO, EC, TSS, Cl-, NO3-, Total-N, Total-P, BOD5, COD, Cr(VI), Cu2+, Ni2+, Pb2+, Cd2+, Total Oil Grass and Temperature. The values of pH, EC, Cl-, NO3-, Total-N, were in all cases within the limits set by EU, WHO and IFC standards, while DOs were below the limit values of 5.0 mg L-1 in all stations. TSS exceeded the limit value 1000 mg L-1 (according to EU standard) at the two Seman stations. Total-P, BOD5 and COD also exceed the limits of EU and WHO but below the limit values of IFC for surface water of oil extraction fields. Total Oil Grass concentrations were > 0.5 mg L-1 (EU standard) and > 10 mg L-1 according to IFC in all cases except for the three values measured in the Zharreza reservoir. The concentrations of Cr (VI), Pb2+ and Cd2+ were higher than three references, and especially Cd2+ and Pb2+ were up to 20 times more than the standard. Also the concentrations of Cu2+ and Ni2+ were higher, according to IFC both upstream and downstream of Seman River as well as in the drainage channel.