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The sandy soils of central and southern Florida have low water and nutrient retention capacities. Excessive irrigation may greatly increase nutrients leaching thereby contribute to contamination of the aquifer under-lying citrus production system. These systems can be managed in such a manner that the excessive downward drainage through the soil is minimized via use of improved irrigation management and/or scheduling strategies which are also critical to maximize water use efficiency. To aid growers in water management decision making, a computer-based decision support system was developed to facilitate more efficient use of water by making use of specific site characteristics and local weather data. System requirements include information on tree age, spacing, soil water holding characteristics, and monthly irrigation set-points for specific production blocks. The user inputs irrigation duration, and/or rainfall depths by block on a daily basis. The soil profile is divided into 40 five cm layers and both irrigated and non-irrigated zones are identified. Horizontal water movement is assumed to be confined within each vertical zone due to lack of lateral movement in the sandy Entisols that prevail in the citrus production region of central Florida. To estimate crop evapotranspiration (ET), daily reference ET values from the Florida Automated Weather Network station nearest the production area are downloaded automatically. Monthly and yearly water use reports are also provided by the decision support system. Appropriate use of this system should not only reduce statewide agricultural water requirements but also nitrogen-loading of groundwater resources associated with citrus production thereby enhancing the profitability and sustainability of Florida citrus production systems.