In enclosed coastal areas, such as estuaries and bays, where water exchange is limited, the discharges of industrial and power plant facilities result in change in the temperature of water. This change threats significantly living organisms in the water. For this reason, the effects of heated discharges must be investigated prior to discharging, considering its near field and far field dilutions. The near field and far field dilutions of thermal discharges are simulated by HYDROTAM-3D which is an unsteady three dimensional baroclinic hydrodynamic and transport model that has been developed to simulate the transport processes in coastal water bodies. It has hydrodynamic, transport, turbulence and wave model components. The model computes the full spatial distribution of velocities of unsteady flow induced by wind, tide or water density differences solving full Navier-Stokes equations with only Boussinesq approximation. The transport model component consists of the pollutant transport model, the water temperature and salinity transport models and the suspended matter transport. The numerical model includes thermohaline forcing due to changes in the sea water density. To consider the large scale turbulence caused by the horizontal shear, horizontal eddy viscosity is simulated by the Smagorinsky algebraic sub grid scale turbulence model. The pollutant transport model can simulate the near and far field dilutions of sea outfalls with a dynamic coupling. Pollutant may be bacteria or heated water. HYDROTAM-3D is integrated with GIS. In the model, wind and wave climate analyses of Turkish coast line exist. Turkish coastline and most of the Turkish Bay bathymetries are provided on GIS mapping. Effect of a thermal discharge rate of 56000 m 3/hour is investigated with its coupled near field and far field dilution modelling.