AbstractA time-dependent three-dimensional free surface model has been applied to Shark Slough. The basin is a very shallow river in Everglades, Florida, U.S.A. The model is being developed as a water management tool to predict water depths in the Slough as a function of managed water discharges from adjacent areas, evapotranspiration and rainfall.The model has been calibrated using data for water year 1978. Coefficients and formulae for evapotranspiration, eddy viscosity and wind stress have been determined. The data base used for comparison consists of surface height measurements at selected locations in the basin. The calibrated model has been used to simulate behavior for water year 1979. Excellent verification with measured data was obtained. The verified model has been used to simulate conditions for extreme years. The model is capable of simulating the movement of domain boundaries as a function of drying or rainfall.