The present work is focused in the risk assessment of surface water in the Lake of Polyfyto, Western Macedonia, Greece. Polyfyto is an artificial lake situated in Northwestern Greece that covers part of the basin of Aliakmon River. Information is presented on water quality variations of temperature, conductivity, transparency, pH, BOD, COD, TKN, NH3, PO4, TP, NO3, NO2, Chlor-alpha, TC, TSS, Cu, Fe, Zn, Mn, Pb, Cr, Ni and Cd, over a period of nine months at three monitoring points in the Polyfyto lake. These measured parameters valued as indicative for the assessment of agricultural, urban and industrial pollution of the Lake providing important information about its physical-chemical and bacteriological behaviour. The sampling and measuring process started on June 2004, it is in access and is taking place once a month until May 2005. The preliminary results of the measuring data show that the concentration of the bacteriological and physicochemical parameters as well as heavy metals analyses have been found to be below the permissible levels of surface water quality standards. Conclusively leaching of the agricultural wastes due to extensive agricultural activities in the area as well as industrial and wastewater treatment effluents are generally at acceptable levels. The aesthetic character of the lake is also at an acceptable level. There is also an improvement observed in comparison to the water quality values observed by previous researchers.
