The research aims to determine a water Quality Index for the Lake of 16 Tishreen Dam. To achieve this aim we have carried out a different periodical physicchemical and bacterial measurements on the water of the lake. The Samples were taken at five sites along the lake for a period of complete year. The indicators that ، NO2، NO3، BOD5، DO، EC، PH، Turbidity،have been measured are: Temperature and ، F.C. Measurement results were represented diagrammatically،PO4،NH4 compared with the Syrian Specification Standards for portable Water. The lake was Canadian Indices ، classed according to these Indices: Malays quality index (NEWWQI). The Lake was Classed according to these indices as ،(NSFWQI) from second grade at ،following:from third grade at all locations (Malays Index) and from ،the middle lake and from a third grade to all other locations (NSFWQI) second grade at all locations (NEWWQI). According to this indices the water is not good for drinking and needs treatment. The Productivity of the lake was determined. The Lake is Eutrophic according to TN-TP in the middle but Hypertrophic accordingtoTN-TP in all other location