The research aims to determine the water Quality Index for the Lake of 16 Tishreen Dam. To achieve this aim, we have carried out different periodical physic-chemical and bacterial measurements on the lake water. The samples were taken at five sites along the lake for a period of one complete year. The indicators that have been measured are: Temperature, Turbidity, PH, EC, DO, BOD5, NO3, NO2, NH4 ,PO4, F.C. Measurement results were represented diagrammatically, and compared with the Syrian Specification Standards for portable Water. The lake was classed according to these Indices: Malays quality index, Canadian Indices (NSFWQI), (NEWWQI). The Lake was Classed according to these indices as following: from third grade at all locations (Malays Index), from second grade at the middle lake and from a third grade to all other locations (NSFWQI), and from 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 according to TN,TP in all other locations.