The MSB model of pollution flushing from a tidal basin, which is based on the analytical tidal prism model developed by Barber, has been applied to embayments with non-constant bathymetry and constant pollution loading. This paper extends the versatility of the MSB model by including alternative pollution loading functions. The model, written in Stella (Stella is a software product and trademark of High Performance Systems, Inc. Hanover, NH 03755 USA), can use both the internal functions of Stella as well as a user-defined functional representation that is part of the Stella toolset. The morphology of a pulse function applied at different times throughout the tidal cycle is studied. Results of these simulations are applied to answer a hypothetical yet useful question: if a certain mass of pollutant must be loaded into a tidal embayment, when should this loading be applied to minimize the time for the concentration to ‘relax’ to a certain critical level? These results and the multiple possibilities for extending the MSB model are explored.