Simulation programs are widely used in engineering education for numerical, modelbased and virtual experimentation, analysis of cause-effect relationships in complex systems, and visualization of challenging concepts. We have developed a pollutant dispersion simulation program applicable in environmental engineering education. The simulation models are implemented in MATLAB and the user interface is provided in the form of a MATLAB GUI. Three types of simulations can be carried out: oxygen sag model for predicting oxygen deficit in a river, Gaussian model for predicting pollutant dispersion in air from a continuous point source, and pollutant dispersion in ground water from a point source. The benefits of using simulation programs for "virtual experimentation" in environmental engineering education and practice are demonstrated and discussed.