Subsurface seepage irrigation is a common method used by growers in the Tri-County Agricultural Area (TCAA), Florida, USA, owing to its cost-effectiveness and low maintenance requirements. This study investigated the lateral flow of the perched water and the lateral transport of bromide (Br) in this irrigation system in the TCAA and estimated the potential discharge of Br into the drainage canals at the edges of the field, using the Visual MODFLOW/ MT3DMS models in conjunction with field experiments. Simulations showed that the perched water flowed from the northeast to the southwest of the field. Migration of the Br plume from the source areas toward the canals was very slow and varied depending on the selection of the outer Br concentration contour levels. However, the lateral transport of Br from the perched water into the canals occurred after about 61 days. The simulations further revealed that the rate of perched water Br discharge into the canals averaged 8.6 g day−1 during a 30-day discharge period (from 61 to 91 days). This rate is very important for estimating Br discharge into the canals and could also provide useful information for evaluating dissolved nutrient discharge into canals from the subsurface seepage irrigation system.