The hydrological function of a karst aquifer is strongly controlled by its physical structure. Observations of physical hydrology and water chemistry along with artificial tracing allow aquifer behaviour to be identified so that hypothetical aquifer structures can be envisaged. Such structures can be evaluated in terms of the geology and geomorphology of the area in question and explained in terms of the geomorphological evolution of the aquifer. A study of the Castleguard Meadows karst aquifer (Rocky Mountains, Alberta) is used to demonstrate this. Four karst springs (one perennial, the remainder intermittent) in one group are considered to be the outlets to a number of conduits. The oldest and largest of these is possibly choked by sediment and acts as a reservoir rather than a conduit, while others convey overflow floods from the upper Saskatchewan Glacier. The aquifer is of great antiquity but has been disrupted by glaciation. The aquifer model developed is a simple hypothesis but provides a valuable research tool suitable for both simulation modelling and the design of further field experiments.