As the first study investigating the effects of WTP discharges on the stream metabolism in Turkey, the results were compared with the previous studies in the literature. The study demonstrated that the WTP discharges increased the mean R_c from −30.6 g O₂ m⁻² day⁻¹ to −130.9 g O₂ m⁻² day⁻¹, and had no significant impact on the mean GPP, statistically (15.6 and 9.1 g O₂ m⁻² day⁻¹ before and after discharges, respectively). Furthermore, the study aimed at statistical modelling the metabolism rates as a function of measured environmental variables. The multiple non-linear regression models of NEM and R_c were derived with high validations (R² of 74.9% and 66.6%, respectively).