Izmir Bay is one of the most polluted estuaries in the whole Mediterranean Sea. 
Especially the Inner Bay is heavily affected by domestic and industrial loads 
amounting to ca. 5 million population equivalents. As a result of these loads, 
strong eutrophication occurs in the inner sections of the Bay, which is 
temporally anaerobic. The ecologically sensitive approach of the local 
authorities in the last decade gave rise to a wide variety of monitoring and 
research studies.

Calibration and validation of the physical component of the model has been 
completed in 1997. Bryan-Cox-Semtner free surface model (KILLWORTH Model) is 
used for this study. Water quality model studies have been initiated by the 
Water and Sewerage Authority in Izmir (IZSU). The main goal of these studies was 
to produce the necessary details to support the decision mechanisms of IZSU. For 
this water quality study, again KILLWORTH Model has been used. The reason for 
this selection is the encouraging recent usage of this model in ecomodeling and 
the already proven power of the background hydrological component.

The wastewater will be discharged into the Middle Bay from the sea surface 
after a mechanical treatment first and a secondary treatment later. So, the 
model experiments are conducted to estimate the distribution of pollutants. In 
the model the continuous discharge of pollutant is represented as a regular 
discharge of discrete particles.