The Umurlu geothermal reservoir located in Buyuk Menderes Graben, Turkey initially contained around 2% by weight CO_2 dissolved in geothermal reservoir fluid. The produced CO_2 rate declined over one year of production time due to dilution of reservoir gas by degassed injectate. Since CO_2 has a considerable role on Umurlu reservoir performance and energy production, produced non-condensable gas (NCG) has been injected simultaneously with colder degassed injectate from an injection well for the last two months. Produced CO_2 monitored in some production wells showed a marked increase as a result of continuous injection. Apart from reducing CO_2 emissions, it has been observed that CO_2 has a profound effect on the behavior of reservoir pressure around these production wells.