Due to the importance and widespread applications of oil products as well as their threats to surface water bodies in Iran, it is inevitable to apply suitable simulation models to develop  management plans, actions, and appropriate scenarios . There are two modified versions of CE-QUAL-W2 and both can be used for simulations of emergency pills of toxic waste in transpotation roadways. In this research, both modified versions were employed to simulate the fate of Methyl tert-butyl ether (MTBE) (a gasoline oxygenated addetive) during an emergency spill.  As a case study, the application of both models was used to evaluate the MTBE emergy spill that occurred on March 2003 near Khalifeh Torkhan river. Several remediation techniques including artificial turbulent, mixing, and aeration were used during the simulation study. Results showed that the modified  version of the model (CE-QUAL-W2) depicted  a better temporal and spatial distribution of MTBE pollution in reservoir compared compared to the first version of the model. Multiple scenarios were simulated in this study under various meteorological, hydrological, and MTBE loading for Gheshlagh reservoir.  The simulation results showed that lower air temperature and  higher  wind speed are among the factors that reduces the reservoir recovery time.  In addition,, another parameter that found to decrease the recovery time of Gheshlagh reservoir is an increase in reservoir inflow and/or outflow rate.