Models are widely used to assist water managers in their duties, yet there is little advice to help water managers select a model appropriate to their particular application. The advice that is available is specific to either the application type or models considered, focused on one aspect of model application, e.g. goodness-of-fit comparisons between observations and simulations and unrealistic, e.g. in separating model selection from wider aspects of the intended application. This paper proposes a model selection protocol that recognises the particular requirements of the application, the roles of individuals associated with modelling studies, and the importance of establishing an informed dialogue between them. Establishing this common understanding at the outset of any modelling study is highly important in securing a successful outcome to the modelling process.