The economic importance of groundwater has increased in recent times. The problem of groundwater contamination and the consequent health threat has been of major concern to groundwater engineers and scientists. This has given rise to an increase in the use of numerical models in predicting contaminant concentrations and travel times in aquifers. In this paper, the numerical model code MOTIF (Model Of Transport In Fractured/porous media) is used to predict the groundwater flow pattern and conservative tracer transport in the Twin Lake aquifer, Ontario. The MOTIF code is a three-dimensional finite element code designed to model the coupled processes of groundwater flow, contaminant and heat transport in porous media. The groundwater flow pattern in the Twin Lake aquifer is simulated in both two- and three-dimensions and the results are compared to field data. The influence of dimensionality on the flow simulation is evaluated by comparing the results of two- and three-dimensional flow simulations. The two sets of flow simulation results were in good agreement with the field data. The results of the three-dimensional flow simulation compared better with the field measurements than those of the two-dimensional simulation. The velocities calculated from the three-dimensional flow model were projected onto a two-dimensional section through the model and used to predict the spatial and temporal distribution pattern of the tracer concentration in a tracer test in the aquifer. The predicted tracer plume compared well with the observed plume in the initial stages but began to show some deviations with time.