Predictions about climate chan-e show that countries in the Mediterranean region will be affected mostly by increasing temperatures and decreasing precipitation. Therefore, it is likely that in the future dry and hot climatic conditions will be prevailing in this region. These changes also affect environments such as rivers whose temperature is directly related to air temperature. Since air temperatures will get higher and drought seasons are expected, the sustainability of fresh water resources will become more important for the future. Therefore fresh water resources must be monitored continuously or at regular intervals and the effects of climate change on these must be investigated. Turkey has a lot of fresh water resources like rivers, lakes and ground water reservoirs but the water demand also will increase with increasing temperatures. Therefore monitoring and future predictions will be required for determining the management alternatives of water use. In this study, statistical assessment of temperature changes of the main rivers in the Mediterranean region of Turkey is carried out. Regression models are developed to predict water temperatures from air temperatures and these are used in future predictions. Results show that significant changes can be expected in near future with possible impacts on the water quality and ecological status of rivers. Quantitative predictions can be achieved to aid managerial actions directed towards the river ecosystems.