Al-Sourani Dam was built to provide drinking water for inhabited villages in Sheikh Badr –Tartous, but the lake water is exposed to pollutants from several sources. In this paper, we discuss the mechanism of pollution and the appropriate measures, by determining some physical, chemical and biological characteristics of water in different sites. The results showed that turbidity and pH values arise in the autumn and winter especially in the water of tributaries compared with the water of the lake, this may be due to the activated runoff following rainfall in this period. Whereas the ammonium ion showed a significant increase in the lake's tail, that can be attributed to sewage residues from Broummana Al-Mashaeikh that threw directly into the lake. The results also showed remarkable seasonal changes concerning the total microorganisms in all studied sites, where the highest value was recorded in winter that reached 5.36 × 104 cells / 100 ml in Aine Alzaaror tributary. we conclude that the main source of pollution of lake's water, was the polluted water coming from Broummana Al-Mashaeikh, in addition to Aine Alzaaror tributary, that flows near a restaurant. The second source is Al-Wade Alakhdar tributary that feeds permanently the lake. So, the lake's water should be sterilized before using for drinking.