The paper describes a regional model of flows in the Biscayne Aquifer of southern Dade County during five consecutive time periods during water years 1945 to 1989 that correspond to stages in the development of a system of levees and controlled canals for water management. Data describing surface-water and ground-water head relations and canal-aquifer head relations are presented and analyzed. The calibrated model is used to numerically assess the effects of the various components of the water-management system.