The province of Bursa is located at the juxtaposition of the West Anatolian extensional zone and the middle and southern branches of the North Anatolian Fault in Turkey. Mount Uludag, which has the highest elevation in Western Anatolia, is also located in the region. The Uludag Massif, whose age is Oligocene, is a leucogranite pluton where numerous thermal, mineral and cold spring water discharges have been observed. These waters are extensively investigated for the first time in this study. Thermal waters discharge in the center of the city of Bursa, north of the Uludag Pluton, and are utilized for balneology and spa purposes in hotels, while mineral waters discharge along a narrow tectonic valley southwest of the Pluton. Mineral waters are bottled and marketed by a few companies in the region. Cold spring waters discharge at different altitudes from Uludag to the Bursa Plain. Temperatures of thermal waters vary between 37 and 80 degrees C in the area of study. Thermal spring waters have been observed of two different compositions due to varying aquifer types: the Cekirge region thermal waters are characterized by Ca-HCO3 type water, while the Kukurtlu region thermal waters, are represented by Na-HCO3 type water, and have the highest temperatures due to deeper zone interaction in the reservoir. Both mineral and cold spring waters are characterized by Ca-HCO3 type water. In the study area, electrical conductivity values vary from 556 to 1352 mu S/cm in thermal waters, while cold water values change between 37 and 472 mu S/cm, and mineral and brackish waters values vary from 1402 to 4500 mu S/cm. Investigation of water-rock interaction effects shows different values for thermal and mineral waters. The delta O-18 values of thermal waters in the region are between -10.09 and -10.87 parts per thousand, whereas the delta O-18 values of mineral waters are between -7.14 and -8.81 parts per thousand. Isotopic signatures of all springs suggest a local meteoric origin of the feed waters from higher levels of the Uludag Pluton. In the study area, the most effective water-rock interaction can be observed in mineral waters. An additional important process is cold water mixing; creating low thermal water temperatures in the study area. Thermal waters in the region show a close relationship with surface water and this effect can be clearly monitored by physical, chemical and isotope analyses during rainy seasons. (C) 2013 Elsevier Ltd. All rights reserved.