The Galyan Stream basin supports the water of Atasu Dam, which will provide domestic water for Trabzon province in Turkey. The Galyan Stream empties into Degirmendere Stream and their water into the Black Sea that these streams are important watersheds in northeastern Turkey. Water samples were periodically taken from Temelli site (Galyan Stream), Degirmen site (Kuştul Stream) and Çiftdere site (Galyan Stream). In this study, at first, variations of dissolved oxygen profile are determined from dissolved oxygen, temperature and carbonaceous biochemical oxygen demand measurements by using Point Resources Streeter- Phelps equation. Water samples are taken from the Galyan and Kuştul Streams. Water quality parameters were analyzed for both streams and evaluated according to the Turkish Water Pollution Control Regulation (TWPCR). Critical dissolved oxygen deficiency values, which were calculated for monthly average (2004 April-2005 January) and annual averages (2000-2004), are seen to be over the limit value in the Galyan Stream having first class water quality in terms of dissolved oxygen concentration, temperature and biochemical oxygen demand. In the following it is disclosed that treatment isn’t required. That study shows that minimum dissolved oxygen limit value (8 mgL^-1), which is desired in domestic waters, is under the limit value in July, August and September months in case of a mixture.