Norovirus is the most acute species among the viruses studied according to the simulations while enterovirus poses the least danger. The relative distance to the contamination sources, wind conditions as well as inactivation rates are essential in determining virus concentrations at a specific site in lakes. Comprehensive studies including QMRA are necessary for risks evaluation. Stochastic simulations can indicate uncertainties in risk assessment. More information on the sewage virus concentration would be important to capture the seasonality of virus contamination.